JPH0153681B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high concentration, high purity dilithium catalyst with excellent storage stability and a method for producing the same. The dilithium catalyst of the present invention is extremely useful for homopolymerization or copolymerization of conjugated dienes and aromatic alkenyl hydrocarbons. As an anionic polymerization catalyst, 2 per molecule of initiator
Dilithium catalysts with active lithium atoms are more useful in the synthesis of double-end functional polymers, block polymers, etc. than general monolithium catalysts.
For example, it is easy to synthesize an ABA3 type block polymer in which the A segment is styrene and the B segment is butadiene, and various dilithium catalysts and the polymerization of dienes using them have been proposed. Such dilithium catalysts are roughly classified into three types depending on their manufacturing method. Specifically, there are three types: those resulting from the reaction of metallic lithium and a dihalogen compound, those resulting from the reaction of metallic lithium with olefins or dienes, and those resulting from the reaction of organolithium with a disubstituted vinyl group or an alkenyl group-containing aromatic hydrocarbon. be. The present invention is based on the third dilithium catalyst known as the most excellent dilithium catalyst among them.
It belongs to the type of Examples of the first type include dilithioalkanes (e.g. 1,4-dilithiobutane) obtained by reacting metallic lithium (dispersion) with dihaloalkanes - US Pat. No. 2,947,793;
An example of the second category is Dilithium Catalyst by Reaction of Lithium Metal with 2,4-Hexadiene - Rubber Chemistry and Technology.
Chemistry and Technology) Volume 49, Page 303,
It is known that it was published in 1976, but all of them have insufficient solubility in hydrocarbon solvents, reproducibility in manufacturing, content of bifunctional components, storage stability, etc. There have been no examples of its use. A third type of dilithium catalyst to which the present invention belongs,
That is, as a dilithium catalyst obtained by the reaction of organolithium with a disubstituted vinyl group or an alkenyl group-containing aromatic hydrocarbon, a dilithium catalyst obtained by the reaction of sec-butyllithium with divinylbenzene has conventionally been used - US Pat. No. 3,668,263. was known. According to the patent, this catalyst contains 98 mol% dilithium compound per lithium, but a relatively recent report states that -
Paper Preserted at the 7th Akron Chemists
―Chemical Engineers―Technical Affiliate
Symposium, Akron (Ohio), October 20, 1977.
The dilithium compound content of the dilithium catalyst is 64
%, and its bifunctionality was highly questionable. Also, sec
- Dilithium catalyst obtained by the reaction of butyllithium and m-diisopropenylbenzene [JP-A-Sho
50-16688 Example 1a], and it is also known that this can be further stabilized by low polymerization of isoprene (as described in US Pat. No. 3,903,168 or
Macromolecules, Vol. 10, p. 287, published in 1977), the former was simply obtained as an intermediate to obtain trilithium, and the latter has been pointed out to not have sufficient bifunctionality. Yes (Makromol.Chem., Vol. 179, p. 551,
Published in 1978 or Polymer, Volume 20, Page 1129,
(published in 1979), and its concentration is too low to be used as a catalyst, and its stability requires storage stabilization by low polymerization of isoprene.
The reactant itself of sec-butyllithium and m-diisopropenylbenzene was only insufficient. As shown above, the dilithium catalysts of the prior art have imperfect concentrations, purity, and stability, are soluble in hydrocarbon solvents, and have concentrations that can be used industrially as polymerization catalysts. The development of a dilithium catalyst with high purity and stability, and a method for easily producing the same, has been a long-standing challenge in the art. The present inventors have completed the present invention as a result of extensive research into the development of the above-mentioned dilithium catalyst. The dilithium catalyst of the present invention is characterized by containing a dilithium compound represented by the following general formula (A) or (B) in an amount of 90 mol% or more based on lithium, as determined by analysis using gel permeation chromatography. do.

【formula】

[Formula] Here, R ₁ and R ₃ are alkyl hydrocarbon groups having 3 to 5 carbon atoms, R ₂ and R ₄ are methyl or ethyl groups, and R ₅ is hydrogen or methyl,
Preferably, R ₁ and R ₃ are a butyl group or a pentyl group, R ₂ and R ₄ are a methyl group or an ethyl group, and R ₅ is hydrogen. More preferably, R ₁
and when R ₃ is a 2-methylbutyl group, R ₂ and R ₄ are a methyl group, and R ₅ is hydrogen, and (A) is more preferable than the above (B). This is due to the ease of manufacturing the dilithium catalyst described below. The dilithium catalyst of the present invention can be prepared by using the above-mentioned dilithium compound using gel permeation chromatography described below to obtain 90 mol% or more based on lithium.
That is, 90 mol% or more of all lithium atoms contained in the dilithium catalyst need to be included as constituents of the above-mentioned dilithium compound. If the content of the dilithium compound is less than 90 mol%, not only will the solubility in hydrocarbon solvents be insufficient and the storage stability will decrease, but also the polylithium coexisting with the dilithium compound in the dilithium catalyst or unreacted Therefore, the polymerization reaction of conjugated dienes or aromatic alkenyl compounds using such a catalyst increases the content of organolithium (monolithium) in the polymer formed by the polymerization reaction of only dilithium compounds. In addition, side reaction products such as star-shaped polymers and crosslinked polymers are formed, which is not only difficult to control the molecular weight of the produced polymer, but also increases the viscosity of the living polymer, which is undesirable. Furthermore, when used in the production of ABA block polymers, the presence of organolithium compounds in the dilithium catalyst results in the formation of AB type polymers.
Such polymers have a negative effect on tensile strength. For the above reasons, the dilithium catalyst used in the present invention needs to contain at least 90 mol% or more of a dilithium compound, more preferably 95 mol% or more of a dilithium compound. The content of the dilithium compound used in the present invention is analyzed as follows. That is, after the dilithium catalyst is deactivated with water in an inert gas atmosphere, gel permeation chromatography of the components contained in the organic layer is performed.
The column used in this case has an exclusion limit molecular weight of 1000~
5000 is preferable, and an ultraviolet absorption photometer (254 nm) is used as a detector. It is possible to identify the oligomer components in the water-deactivated catalyst using a column calibration curve using polystyrene as a standard sample, and to analyze the ratio of each component based on their molecular weights. Examples of analysis by gel permeation chromatography are shown in FIGS. 1 to 3. “Dilithium compounds” can be reliably separated and analyzed from other impurity compounds. Further, unreacted organolithium compounds contained in the catalyst are separately analyzed by gas chromatography using water-deactivated samples and active samples. Therefore, it is possible to calculate the true dilithium compound content using the above analysis values. The content of the dilithium compound analyzed and calculated in this way has a more direct and accurate value than the above-mentioned conventional analysis method. For example, the results of using this technique to analyze various known catalysts, the intermediates (dilithium catalysts before stabilization by low polymerization of isoprene) of the aforementioned U.S. Pat. No. 3,668,263 and U.S. Pat. It was only about 70 mol% and about 45 mol%. The dilithium catalyst of the present invention is characterized by being soluble in hydrocarbon solvents at high concentrations. Hydrocarbon solvents include commonly known aliphatic or aromatic hydrocarbons, such as n-hexane, n-pentane, n-heptane, n-octane, isooctane, cyclopentane, cyclohexane, benzene, toluene, ethylbenzene, Propylbenzene is preferred, and its concentration, expressed as lithium atoms/hydrocarbon solvent, is preferably 0.3 mol/liter or more. In general, a dilithium catalyst having too low a concentration has insufficient storage stability and requires a large capacity for use, which may cause inconveniences in its addition to the polymerization system, for example, which is not preferred. The dilithium catalyst of the present invention is characterized by the coexistence of a tertiary monoamine. Preferred tertiary monoamines include trimethylamine, triethylamine, tri-n-propylamine, N,
Examples include N'-dimethylaniline and N,N-diphenylmethylamine. Most preferred is triethylamine. Further, the amount of the tertiary monoamine present is preferably an amount that satisfies the condition of the following formula (C). log y＞log x−0.5 ...(C) (where x is the molar ratio of tertiary monoamine to lithium atom, y is the concentration expressed as tertiary monoamine/hydrocarbon solvent; unit mole/liter , x > 0.5) The coexistence of an appropriate amount of tertiary monoamine has the effect of significantly improving the storage stability of the dilithium catalyst, and its amount is regulated by the molar ratio to lithium atoms and the concentration in the hydrocarbon solvent. If it is outside this range, the storage stability will be insufficient, or there will be restrictions on the production of the dilithium catalyst described below, which is not preferable. The aromatic alkenyl hydrocarbon used in producing the dilithium catalyst of the present invention has the structure of the following formula (A') or (B').

【formula】

[Formula] Here, R' ₂ and R' ₄ are a methyl group or an ethyl group, and R' ₅ is a hydrogen or methyl group. Examples of such compounds include m-diisopropenylbenzene and p-diisopropenylbenzene. ,1,3-
Bis(1-ethylethenyl)benzene, 1,4-
Bis(1-ethylethenyl)benzene, and the methyl derivatives mentioned above. When R' ₂ and R' ₄ are hydrogen, it is difficult to avoid oligomerization of the aromatic alkenyl hydrocarbon, and when R' ₂ and R' ₄ are alkyl groups with 3 or more carbon atoms, , the reaction activity becomes too small due to the bulk of the displacement device. Furthermore, the m-isomer is more preferable than the p-isomer, because the p-isomer forms a resonance structure between the living anion and the aromatic ring and is stabilized, whereas the m-isomer does not. This is thought to be due to the fact that it is unable to form a rigid structure and can be more activated. In addition, as an organolithium compound, the general formula
Those represented by R ₆ --Li (R ₆ is an alkyl group) can be used. Examples of such include n-butyllithium, sec-butyllithium, tert-butyllithium, 2-methyl-propyllithium, ethyllithium, propyllithium, and i-propyllithium, but particularly preferred organic lithium compounds include: sec-butyrlithium. The amount of the organolithium compound used in the present invention is desirably strictly twice the mole of the aromatic alkenyl hydrocarbon, but may be increased or decreased by about 5% depending on the case. When the amount of the organolithium compound significantly exceeds 2 times the mole of the aromatic alkenyl hydrocarbon, for example, when using 2.5 times the mole or more, the amount of unreacted organolithium compound becomes too large. If the amount is extremely small, for example 1.5 times the mole or less,
Oligomerization of aromatic alkenyl hydrocarbons becomes predominant, making it impossible to achieve the object of the present invention. As the reaction solvent of the present invention, generally known aliphatic or aromatic hydrocarbons can be used. Such examples include n-hexane, n
-Heptane, n-octane, isooctane, cyclopentane, cyclohexane, benzene, toluene, ethylbenzene, propylbenzene, and a mixed solvent of any two or more of these can be used, but preferably n- These are hexane, cyclohexane, and benzene. The concentration of reaction materials for these hydrocarbon solvents is based on lithium atoms/hydrocarbon solvent.
It is preferably 0.3 mol/liter or more.
If the concentration is lower than this, the high concentration and high purity dilithium catalyst of the present invention cannot be obtained. Additives preferably used in the present invention include trimethylamine, triethylamine,
Examples include tertiary monoamines such as tri-n-propylamine, N,N'-dimethylaniline, and N,N-diphenylmethylamine. N, N, N′,
When using tertiary diamines such as N'-tetramethylethylenediamine and dipiperidinoethane,
Due to the chelating effect of the amino group, the coordination with Li ions is too strong and does not give the desired result. Furthermore, when ethers such as diethyl ether and tetrahydrofuran are used as additives, undesirable side reactions such as metalation occur due to the strong polar action of oxygen atoms. Furthermore, when these highly polar additives are used, they have a significant effect on the microstructure of the conjugated diene polymer.
Control is often difficult. Therefore,
Depending on the target polymer, it is likely to have undesirable effects, so it is preferable to use a compound that is as weakly polar as possible. Particularly preferred in the present invention is triethylamine. Furthermore, the amount of tertiary monoamine used as an additive is characterized in that it satisfies the following formula (C). log y＞log x−0.5 ...(C') (where x is the molar ratio of tertiary monoamine to lithium atom, y is the concentration expressed as tertiary monoamine/hydrocarbon solvent; unit mole/liter ,
However, x > 0.5) In the above, when x is 0.5 or less, the amount of dilithium compound formed by the reaction between the organolithium compound and the aromatic alkenyl hydrocarbon is significantly reduced, and the polylithium compound as a concerted reaction It becomes difficult to suppress the generation of Furthermore, x
Even when the ratio exceeds 0.5, the content of the dilithium compound differs depending on the additive concentration. If the additive concentration is too low, the effectiveness of the additive in contributing to the formation of dilithium compounds is significantly reduced. Therefore, in order to obtain the desired dilithium catalyst containing 90 mol% or more of a dilithium compound, each additive containing a certain concentration or more must be added depending on the molar ratio of the additive used to the organic lithium compound. need to be done. In the present invention, the relationship can be expressed by the above equation (C'), preferably log x+0.3>log y>log x-0.5. Further, when triethylamine is used as the tertiary monoamine, in order to achieve the object of the present invention, it is preferable to carry out the reaction for a certain period of time or longer, depending on the amount of triethylamine added and the reaction temperature. Generally speaking, the larger the amount of triethylamine used and the higher the reaction temperature, the shorter the time required for the reaction. However, if the amount of triethylamine added is too large, it is generally undesirable in view of the influence on the microstructure of the polymer. Furthermore, if the reaction temperature is too high, side reactions such as oligomerization of the aromatic alkenyl hydrocarbon become dominant, and lithium is undesirably deactivated. In the present invention, the preferable conditions that the reaction time satisfies are: x∫ ^t _p Tdt>1000...(E) (where x is the molar ratio of triethylamine to 1 mole of the organolithium compound, T is the reaction temperature;
The unit is °K, and t is the reaction time; the unit is hr. ). In the above formula (E), if the reaction temperature T is constant, the formula (E) can be further rewritten as the following formula (F). t>1000/x 1/T... (F) That is, the effect of the present invention is achieved when the reaction time t, the amount x of triethylamine added, and the reaction temperature T satisfy the relationship of the above formula (F). becomes a significant source. The dilithium catalyst obtained in this way is completely soluble in hydrocarbon solvents, has high concentration, high purity, and high stability. It can be used alone or in combination with mono- or other polylithium catalysts. When used alone, the block copolymer produced can be widely used as a thermoplastic elastomer or resin for injection molded products such as tires, footwear, or containers, compression molded products such as packing, plates, and sheets, or adhesives,
Useful as a component of paints or coatings. In addition, polymers with functional groups at both ends are subjected to various treatments such as hydroxylation, carboxylation, and maleation to introduce polar groups or impart crosslinking properties, and such modified polymers are are useful as prepolymers for a variety of applications, such as hydroxylation followed by reaction with isocyanates to produce polyuthalenes. The thermoplastic styrene-butadiene copolymer obtained using the catalyst of the present invention has extremely excellent breaking strength. Furthermore, when mixed with other polyfunctional polylithium catalysts depending on the purpose,
The resulting copolymer has desired values of tear strength and breaking strength, and when the catalyst of the present invention is used to produce a styrene-butadiene copolymer and the styrene content is high, the impact strength is low. It is also possible to obtain resinous copolymers with high . Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 m-diisopropenylbenzene is
Macromolecules, 10 (2), 287 (1977). In addition, sec-butyllithium is produced by J.
Amer.Chem.Soc., 91 , 6362 (1969), prepared in cyclohexane solvent at a concentration of 1.2-2.5N. A magnetic stirrer was inserted and the rubber seal was sealed.
Replace the 100ml glass bottle with nitrogen and use this
1.48Nsec - Butyl lithium 42.7 ml (63.2 mmol), triethylamine 8.7 ml (63.2 mmol),
and 6.6 ml of cyclohexane were introduced at 20°C,
Mix by stirring in a bottle. Furthermore, 5 g (31.6 mmol) of m-diisopropenylbenzene was added dropwise from a syringe over 1 hour. The reaction mixture turned into a deep red clear solution over time with no visible precipitate. Sampling was carried out as follows while stirring was continued from the end of dropping m-diisopropenylbenzene. That is, 10 ml of the reaction solution was deactivated with water in a separate bottle purged with nitrogen, and the organic layer was subjected to gel permeation chromatography using chloroform as an eluent, and the dilithium component was analyzed using an ultraviolet spectrophotometer (254 nm). Measurements were made. In addition, sec-butyllithium was determined in the gas phase by gas chromatography. The results are shown in Table 1. Further, FIG. 1 shows GPC charts of samples obtained immediately after the start of the reaction (a), 8 hours after the start of the reaction (b), and 48 hours after the start of the reaction (c). FIG. 1 shows that impurities such as (b) and (c) that were present immediately after the reaction decreased as the reaction time progressed, and after 8 hours, most of the impurities were converted to dilithium compounds (a).
(Table 1 shows the dilithium content after 5.4 hours of this experiment, which is 98%. The content of this chart after 8 hours is also 98%.) Furthermore, even after 48 hours, the dilithium content is over 99%. It can be seen that it is a dilithium compound (a). Examples 2 to 5, Comparative Examples 1 to 4 The same operation as in Example 1 was performed except that the concentration of triethylamine and the reaction temperature were changed. The conditions and results are shown in Tables 1 and 2. Further, FIGS. 2 and 3 show GPC charts of samples obtained 48 hours after the reaction for Comparative Example 2 and Comparative Example 3, respectively. Figures 2 and 3 show that if the reaction conditions are not appropriate, there will be many impurities such as (b), (c), and (d) even after 48 hours of reaction time, and the dilithium content will be low. I understand that. Note that each of the peaks (a) to (e) is the following lithium compound according to the calibration curve. (A): Dilithium Examples 6 and 7 Example 1 except that in Example 6, sec-butyllithium was replaced with i-propyllithium, and in Example 7, sec-butyllithium was replaced with tert-butyllithium, and the concentration of triethylamine was changed.
I performed a similar operation. The conditions and results are shown in Table 1. Comparative Example 5 The same operation as in Example 1 was carried out except that m-diisopropenylbenzene was added dropwise at -20°C for 2 hours and then the reaction temperature was further raised to 30°C. The conditions and results are shown in Table 2. Comparative Examples 6, 7 In Comparative Example 6, diethyl ether was used instead of triethylamine, and in Comparative Example 7, N, N, N', N'-
The same operation as in Example 1 was performed except that trimethylethylenediamine was used instead. The conditions and results are shown in Table 2. Comparative Examples 8 and 9 In Comparative Examples 8 and 9, the same operation as in Example 1 was performed except that m-sivinylbenzene was used instead of m-diisopropenylbenzene and the concentration of triethylamine and reaction conditions were changed. . The conditions and results are shown in Table 2. Tables 1 and 2 show that the dilithium catalyst obtained by the production method of the present invention has a high concentration, has a dilithium compound content of 90 mol% or more, and has extremely excellent solubility and stability. I know that there is.

【table】

【table】

[Table] Using the dilithium catalysts produced in Examples 1, 2, and 4 and Comparative Examples 2, 5, and 7, 60 g of butadiene was dissolved in n-hexane in a nitrogen-purged bottle under the conditions shown in Table 3. Polymerize at 60℃ for 1 hour, and then
After additionally adding 40 g of styrene, polymerization was carried out at 70°C for 2 hours. The obtained block copolymer was deactivated with methanol, vacuum-dried at room temperature for 3 days, and then subjected to physical property evaluation. The evaluation results are shown in Table 3. It can be seen that the dilithium catalyst of the present invention has favorable polymerization activity, and the resulting block copolymer has extremely excellent physical properties, such as high tensile strength.

【table】 [Brief explanation of drawings]

FIG. 1 shows GPC charts of samples obtained in Example 1, a, immediately after the start of the reaction, b, 8 hours after the start of the reaction, and c, 48 hours after the start of the reaction. Figures 2 and 3 are Comparative Example 2, respectively.
and a GPC chart of a sample obtained 48 hours after the reaction in Comparative Example 3. Analyzer: Waters Model 244 high performance liquid chromatograph, Detector: Waters Model 440 (UV-254nm), Column: 7.4 mmi.d. x 50 cm (M.
lim.=3400), eluent: chloroform, flow rate: 1.0
ml/mim.

Claims (1)

[Scope of Claims] 1 A dilithium compound represented by the following general formula (A) or (B) is analyzed using gel permeation chromatography and contains 90% or more in mole per lithium, and has the following formula ( A dilithium-based catalyst effective for homopolymerization or copolymerization of conjugated dienes and aromatic alkenyl hydrocarbons, characterized by the presence of a tertiary monoamine that satisfies the condition C). [Formula] [Formula] (In the formula, R ₁ and R ₃ represent an alkyl hydrocarbon group having 3 to 5 carbon atoms, R ₂ and R ₄ represent a methyl group or an ethyl group, and R ₅ represents a hydrogen or methyl group.) log y＞log x−0.5 ...(C) (where x is the molar ratio of tertiary monoamine to lithium atom, y is the concentration expressed as tertiary monoamine/hydrocarbon solvent; unit mole/liter,
However, x > 0.5) 2 2 moles of the organolithium compound represented by the following general formula (D) per 1 mole of the aromatic alkenyl hydrocarbon represented by the following general formula (A') or (B'). When reacting in a hydrocarbon solvent, the concentration of the organolithium compound represented by the general formula (D) is 0.3 mol/liter or more expressed as lithium atoms/hydrocarbon solvent, and the conditions of the following formula (C') are met. A method for producing a dilithium-based catalyst useful for homopolymerization or copolymerization of conjugated dienes and aromatic alkenyl hydrocarbons, characterized in that a tertiary monoamine satisfying the following is present.