JPH08319308A - Production of polymer - Google Patents

Abstract

PURPOSE: To obtain a polymer in good productivity by adding a specific halogenated organometallic compound to a polymerization system of a conjugated diene and/or a vinyl aromatic hydrocarbon comprising an organolithium compound as an initiator, having a small hysteresis loss, excellent in processability. CONSTITUTION: (B) A conjugated diene (especially preferably 1,3-butadiene) and/or a vinyl aromatic hydrocarbon (especially preferably styrene) is polymerized by using (A) an organolithium compound (preferably n-butyllithium or tert-butyllithium) as an initiator. In a polymer chain growth period from a time immediately after the starting of the polymerization to a time before its completion, (C) a halogenated organometallic compound of the formula (M is Sn, Si, Ge or Pb; R is a 1-30C aliphatic, alicyclic or aromatic hydrocarbon; X is Cl, Br or I; (n) is an integer of >=1) in an amount of preferably 0.2-1mol equivalent, especially preferably 0.3-0.5mol equivalent calculated as a metal is added to 1mol of a polymer chain growth end Li to carry out the polymerization reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a polymer which has a small hysteresis loss and is excellent in workability and can be obtained with high productivity.

[0002]

2. Description of the Related Art In recent years, automobiles are required to have low fuel consumption. Therefore, a rubber having a small hysteresis loss and good workability is desired as a rubber for a tire material. Therefore, natural rubber, polyisoprene rubber, polybutadiene rubber, or the like, which is known as a rubber material having a small hysteresis loss, is used. Further, as a synthetic rubber having a significantly improved low hysteresis loss, there is a polymer prepared by polymerizing an organolithium compound as an initiator in a hydrocarbon solvent and coupling a tin halide compound to the end of the polymer (JP-A-57-5).
5912). This polymer is a polymer having very excellent physical properties, and is used in a rubber composition for a tire having low rolling friction resistance and low fuel consumption.

In the method for producing this polymer, when a tin halide compound is used to cause a coupling reaction at the terminal of the polymer, the polymerization reaction system becomes inactive at the stage when the tin compound is added, and the residual monomer remains. It is considered that it remains unreacted, and the molecular structure of the obtained polymer is determined at the time when the tin compound is added, and since it has a molecular structure containing tin in the molecular chain, the reaction surface, that is, economical efficiency. From the viewpoint of, and both sides of the molecular structure, that is, the viewpoint of molecular design, in order not to leave unreacted monomer,
A tin compound is added when the polymerization reaction is completed.

As described above, in the conventional method for producing a polymer by using a modifier such as a coupling agent such as a tin halide compound, the modifier is added after the polymerization, and if unreacted at this point. Even if the monomer remains, the batch polymerization method is adopted, which is followed by the step of recovering the target polymer, but the batch polymerization method has poor productivity as compared to the continuous polymerization method, leading to high manufacturing cost. As a result, there is a problem that the polymer becomes expensive.

On the other hand, various other continuous polymerization methods are known, but at the same time, a method for producing a polymer having a small hysteresis loss and a sufficiently excellent processability and high productivity is not yet known.

Further, according to the conventional method by the coupling reaction between the active terminal lithium of the polymer and the tin halide compound, even if the tin halide compound is reacted in an amount equivalent to the active lithium, the reaction is theoretically 100%. Does not occur, and industrially remains at about 60%.
That is, it cannot be said that the conventional method is sufficient even if a polymer having a small hysteresis loss is obtained.

Further, the conventional polymer obtained by coupling a polymer having an active terminal with a metal halide compound or the like can improve various properties, but on the other hand, it has a very high molecular weight polymer. Therefore, it has a drawback that the workability becomes difficult.

In order to solve these problems, the present inventors previously added a specific organotin compound to the polymer undergoing the polymerization chain formation reaction to have a low hysteresis loss effect and excellent workability. It was found that the above polymer was obtained by a continuous polymerization method, and a patent application was filed (JP-A-6-192310). According to this production method, a polymer having a small hysteresis loss can be efficiently obtained by the continuous polymerization method, but further improvement has been desired from the viewpoint of improving processability.

[0009]

That is, an object of the present invention is to provide a novel method for producing a polymer, which is excellent in processability and has a small hysteresis loss, and which can be obtained with high productivity. .

[0010]

The method for producing a polymer according to claim 1, wherein a conjugated diene and / or a vinyl aromatic hydrocarbon is polymerized in a hydrocarbon solvent with an organolithium compound as an initiator to carry out polymerization. It is characterized in that a halogenated organometallic compound represented by the following general formula is added to the polymerization system for growing a polymerization chain terminal lithium to carry out the polymerization reaction immediately after the start and before the end of the polymerization chain growth.

[0011]

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(In the formula, M represents a metal selected from tin, germanium and lead, R represents an aliphatic group having 1 to 30 carbon atoms,
It represents an alicyclic or aromatic hydrocarbon group, X represents a halogen atom selected from chlorine, bromine and iodine, and n represents an integer of 1 or more. Hereinafter, the compound represented by this general formula is abbreviated as (RMX) _n .

The present inventors have paid attention to the polymerization reaction by organolithium, the interaction between this polymerization active terminal lithium and the organometallic compound, the reactivity of the interaction generation system, etc. When a specific amount of the halogenated organometallic compound according to the present invention is added to the system after initiation, a new type of metal-lithium initiator having polymerization activity is produced,
It was found that the polymerization reaction was continued and a polymer containing a metal-carbon bond chain was produced, and the obtained polymer satisfied the above-mentioned various properties. The mechanism is considered to be as represented by the following reaction formula.

[0014]

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(In the formula, P and P'represent a polymer before and after binding to the halogenated organometallic compound, respectively.) That is, the present invention is applied to the low molecular weight polymer (a) during the growth of the polymerization chain. If the halogenated organometallic compound (b) is added in an amount of less than 1 in terms of metal / lithium molar ratio, a coupling reaction occurs and a metal-carbon bond chain-containing low molecular weight polymer (c) is produced. This polymer (c) further undergoes a coupling reaction with the polymer (a), and finally, a metal-carbon bond chain-containing low molecular weight polymer (P in the above reaction formula) having two low molecular weight polymerization chains ( generated by d). This (d) has the ability to initiate polymerization by M (metal) -Li, so that the polymerization of the monomer continues, the chain grows (has a high molecular weight polymerized chain P ′), and the content of the metal-carbon bond chain is high. A molecular weight polymer (e) is obtained, and since (e) has an active end, it can easily react with the modifier.

The polymer (e) exhibits various properties by breaking the bonds between PM and MP 'due to stearic acid or heat generation during kneading. Focusing on P obtained by cleavage, the molecular weight of P can be easily adjusted by the timing and amount of addition of (b) after the initiation of polymerization, and does not change until the polymer (e). Similarly, for the molecular weight of P '(b)
It is adjusted according to the addition timing and the addition amount. If P is controlled to a low polymer having an appropriate molecular weight by these,
This low molecular weight polymer makes the polymer of the present invention extremely excellent in processability. Further, by delaying the addition time of (b) after the initiation of polymerization until the completion of polymerization, a polymer having two relatively high molecular weight polymerized chains P and one relatively low molecular weight polymerized chain P ′ is obtained. You can also

Regarding P ', although one end is modified in the above reaction formula, both ends of P'Li can be modified by modifying P'Li, so that an extremely large low hysteresis loss effect can be obtained at the time of kneading with carbon black. can get. Therefore, since the polymer (e) is effective for improving the processability of the low molecular weight component (P) and the low hysteresis loss effect of the high molecular weight component (P '), it can be said that the polymer has both properties.

The present invention will be described in more detail below. In the production method of the present invention, those used as a polymerization solvent include, for example, aromatic hydrocarbon solvents such as benzene, toluene and xylene, aliphatic hydrocarbon solvents such as n-pentane, n-hexane and n-butane, Methylcyclopentane,
Alicyclic hydrocarbon solvents such as cyclohexane and mixtures thereof can be used.

Organolithium compounds used as an initiator in the present invention include ethyllithium, propyllithium, n-butyllithium, sec-butyllithium and te.
rt-Butyl lithium, alkyl lithium such as hexyl lithium, aryl lithium such as phenyl lithium, 1,
Examples thereof include alkylenedilithium such as 4-dilithiobutane, stilbendilithium, and lithium hydrocarbon such as a reaction product of butyllithium and divinylbenzene. Preferred is n-butyl lithium or tert-butyl lithium. These organolithium compounds may be used alone or in combination of two or more. The amount of these organolithium compounds used can be in the range of 0.2 to 30 mmol per 100 g of the monomer.

To obtain the polymer of the present invention, the monomers used for the polymerization are conjugated dienes and / or vinyl aromatic hydrocarbons, the conjugated dienes having 4 to 12 carbon atoms per molecule, preferably It is a conjugated diene hydrocarbon containing from 4 to 8. For example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
Examples include 1,3-pentadiene and octadiene.
These may be used alone or in combination of two or more, and 1,3-butadiene is particularly preferable.

The vinyl aromatic hydrocarbon includes styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-butylstyrene, vinylnaphthalene and the like, and particularly styrene. preferable.

Structural formula of the present invention (RMX)_nRepresented by
In the halogenated organometallic compound, M is tin or g
Represents a metal selected from rumanium and lead, where R is the carbon number
Represents 1 to 30 aliphatic, alicyclic or aromatic hydrocarbon groups
Where X is a halogen source selected from chlorine, bromine and iodine
Represents a child, and n represents an integer of 1 or more. (RMX)_n
In the case of n = 1 and 2, the RMX monomer
And a dimer having an M-M bond, where n ≧ 3
, Tetramer, which forms a ring by MM bond,
Represents a cyclic polymer such as Preferred of M is tin
Is. Further, among R, those having 1 to 20 carbon atoms are preferable.
The hydrocarbon group, for example, methyl, ethyl,
Propyl, n-butyl, sec-butyl, tert-butyl,
Octyl, naphthyl, cyclohexyl, cyclopentadi
Examples include enyl, phenyl, and benzyl groups.
It Preferred among X is chlorine or bromine. Possible
The value of n depends on the reactivity of RMX mainly depending on the type of R.
Since they are different, they are not uniform and cannot always be specified.
Generally, 1 to 6 are preferable. (RMX)_nas,
For example, M is tin, X is chlorine, and R is the carbonization above.
RMX monomer (n = 1), which is a hydrogen group, dimer
(N = 2) and oligomers (3 ≦ n ≦ 6).
Can be, for example, cyclohexyl tin chloride monomer,
Examples thereof include cyclohexyl tin bromide monomer.

The addition amount of the halogenated organometallic compound represented by the structural formula (RMX) _n of the present invention is 0.2 to M as M in (RMX) _{n with} respect to 1 molar equivalent of lithium in the polymer chain growth terminal. From the viewpoint of being less than 1 molar equivalent, increasing the ratio of the metal-carbon bond chain-containing polymer in the polymer, efficiently and highly maintaining the polymerization activity, and obtaining a polymer having an appropriate molecular weight, it is preferably 0. .3 to 0.5 molar equivalent. If the amount added is less than 0.2 molar equivalent, the chain growth of the metal-carbon bond chain-containing polymer chain will occur, but the polymerization that proceeds independently of this mechanism, that is, the polymerization with a normal lithium initiator that does not contain tin, will occur. Since it occurs frequently, the ratio of the metal-carbon bond chain-containing polymer in the obtained polymer decreases, and the desired physical properties become poor, which is not preferable. On the other hand, when the added amount is 1 molar equivalent or more, the active terminal lithium is deactivated and the chain growth reaction is stopped. The necessary amount of the organometallic halide compound represented by the structural formula (RMX) _n of the present invention may be added at once or continuously during the progress of the polymerization reaction.

In the present invention, the timing of the addition of the halogenated organometallic compound is an important factor for achieving the object of the present invention, and the polymerization system may be added from immediately after the initiation of the polymerization with the organolithium compound to before the completion of the polymerization chain. Is added in.

The timing of this addition is not particularly limited because it varies depending on the monomer concentration, the organolithium initiator concentration, etc., but it is generally preferable to be in the initial stage of polymerization. This is the polymer P in the reaction formula 1 as described above.
This is because the object of improving the processability of the polymer of the present invention is highly achieved by suppressing the content of the polymer to a low molecular weight. Here, the initial stage means, for example, that the polymer conversion rate is 5 to 25%.
Means degree.

In the present invention, the polymerization activity is improved and / or
Ordinarily used for this purpose in order to adjust the molecular structure of the desired polymer (molecular weight, microstructure, in the case of a copolymer, in addition to this, the composition of monomer units and its composition distribution, etc.) according to the application. The additive, that is, the randomizer can be added. The randomizer here is
Control of microstructure of conjugated diene polymer, for example, 1,2 bond of butadiene part of butadiene polymer or butadiene-styrene copolymer, 3,4 of isoprene polymer
A compound having an action of increasing the number of bonds and the like, and controlling the composition distribution of the monomer unit of the conjugated diene-vinyl aromatic hydrocarbon copolymer, for example, the butadiene unit of the butadiene-styrene copolymer, the randomization of the styrene unit, etc. Is. The randomizer according to the present invention is not particularly limited, but includes all commonly used randomizers. Examples of the randomizer used include the following. (1) Ethers (2) Ortho-dimethoxybenzenes (3) Complex of alkali metal and ketone or phosphite triester (4) Compound represented by the following general formula R (OM ¹ ) _n , (RO) ₂ M ² , R (COOM ¹ ) _n , RO
COOM ¹ , RSO ₃ M ¹ , ROSO ₃ M ¹ (wherein R is selected from aliphatic, alicyclic and aromatic hydrocarbon groups, M ¹ is an alkali metal,
In particular, it represents lithium, sodium, potassium, rubidium or cesium, M ² is an alkaline earth metal, specifically calcium or barium, and n is from 1 to 1.
It is an integer of 3. (5) Tertiary amine The randomizer will be specifically described below, but these randomizers may be used alone or in combination.

(1) Examples of ethers include 1,2-
Examples thereof include dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methoxymethyltetrahydrofuran, diethyl ether, triethylene glycol dimethyl ether and the like.

(2) Examples of orthodimethoxybenzenes include veratrol, isohomoveratrol and the like.

(3) The complex of an alkali metal with a ketone or phosphite triester includes ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, benzophenone, acetophenone, dibenzyl ketone, fluorenone, xanthone, Michler's ketone and acetylacetone. Phosphite triesters such as triethyl phosphite, trioctyl phosphite, tribenzyl phosphite and trinonyl phosphite,
Examples thereof include complexes with lithium, sodium, potassium, rubidium or cesium.

(4) The randomizer represented by the general formula will be described. Specific examples of the alcohol represented by the general formula R (OM ¹ ) _n or (RO) ₂ M ² and the alkali metal salt or alkaline earth metal salt of phenol include methyl alcohol, ethyl alcohol, isopropyl alcohol, tert.
-Butyl alcohol, tert-amyl alcohol, cyclohexyl alcohol, allyl alcohol, 2-butenyl alcohol, benzyl alcohol, phenol, catechol, resorcinol, hydroquinone, 1-naphthyl alcohol, p-nonylphenol, pyrogallol, etc. lithium, sodium, potassium, Rubidium, cesium, calcium and barium salts are included.

The general formula R (COOM ¹ ) _n or ROCOOM
Specific examples of the alkali metal carboxylic acid and acidic carbonic acid ester salt represented by ¹ , are isovaleric acid, lauric acid,
Palmitic acid, stearic acid, oleic acid, rosin acid,
Examples thereof include lithium, sodium, potassium, rubidium and cesium salts such as benzoic acid, pimelic acid, acidic n-dodecyl carbonate and acidic phenyl carbonate.

Specific examples of the alkali metal sulfonic acid and sulfate ester salt represented by the general formula RSO ₃ M ¹ or ROSO ₃ M ¹ include dodecylbenzene sulfonic acid,
Diisopropylnaphthalenesulfonic acid, N-methyl-N
Includes lithium, sodium, potassium, rubidium and cesium salts such as methane sulfonate lauryl amide, sulfate salt of lauryl alcohol, caproyl ethylene glycol sulfate ester.

(5) Examples of tertiary amines include triethylamine and tetramethylethylenediamine.

Among them, preferable randomizers include the above-mentioned (1) ethers and the above-mentioned (4) R (OM ¹ ) _{n, which} are particularly easy to control the molecular structure of the polymer of the present invention.

The amount of the randomizer used is 0.01 to 1000 per 1 mol equivalent of the organolithium halide compound.
Used in a molar equivalent range.

In the production of the polymer of the present invention, when the continuous polymerization method of the present invention has to be interrupted or terminated for the convenience of the process, or when the molecular design is changed to impart desired physical properties to the polymer, etc. In, after completing the polymerization reaction, a compound that reacts with the active end of the polymer chain, for example, a silicon compound, a tin compound, an isocyanate group-containing compound in the molecule, or -CM-N <bond (M: O or S) content At least one compound selected from the compounds can be added as a modifier.

Specific examples of the modifier will be given below. Examples of the silicon compound used as the modifier include silicon tetrachloride, chlorotriethylsilane, chlorotriphenylsilane, dichlorodimethylsilane and the like.

Examples of the tin compound used as a modifier include tin halides such as tin tetrachloride and tin tetrabromide, and diethyldichlorotin, dibutyldichlorotin, tributyltin chloride, diphenyldichlorotin and triphenyltin chloride. Examples thereof include tin compounds.

Examples of the isocyanate group-containing compound used as a modifier include phenyl isocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate and dimers thereof,
Examples include trimer aromatic polyisocyanate compounds.

Examples of the compound containing -CM-N <bond (M: O or S) include formamide, N, N-dimethylformamide, acetamide, N, N-diethylacetamide, aminoacetamide, N, N-dimethyl. -N ', N'-dimethylaminoacetamide, N, N-dimethylaminoacetamide, N, N-dimethyl-N'-
Ethylaminoacetamide, acrylamide, N, N-
Dimethylacrylamide, N, N-dimethylmethacrylamide, nicotinamide, isonicotinamide, picolinic acid amide, N, N-dimethylisonicotinamide, succinic acid amide, phthalic acid amide, N, N, N ', N'-tetra Methyl phthalamide, oxamide, N, N, N ',
N′-tetramethyloxamide, 1,2-cyclohexanedicarboximide, 2-furancarboxylic acid amide,
Amide compounds such as N, N-dimethyl-2-furancarboxylic acid amide, quinoline-2-carboxylic acid amide, N-ethyl-N-methyl-quinolinecarboxylic acid amide, succinimide, N-methylsuccinimide, maleimide, N- Imide compounds such as methylmaleimide, phthalimide and N-methylphthalimide, ε-caprolactam, N-methyl-ε-caprolactam, 2-pyrrolidone, N-methyl-
Lactam compounds such as 2-pyrrolidone, 2-piperidone, N-methyl-2-piperidone, 2-quinolone, N-methyl-2-quinolone, urea, N, N′-dimethylurea,
Urea compounds such as N, N-diethylurea, N, N, N ', N'-tetramethylurea, N, N-dimethyl-N', N'-diphenylurea, N, N'-dimethylethyleneurea,
Carbamate derivatives such as methyl carbamate, N, N-diethyl carbamate, isocyanuric acid, N,
Examples thereof include isocyanuric acid derivatives such as N ′, N ″ -trimethylisocyanuric acid and their corresponding thiocarbonyl-containing compounds, etc. The modifier is not particularly limited as long as it is a compound that reacts with the active end of the polymer chain.

The polymerization temperature is usually from -20 to 150 ° C,
It is preferably 0 to 120 ° C. The monomer concentration in the solvent is usually 5 to 50% by weight, preferably 10 to 3%.
It is 5% by weight. In the case of copolymerization of conjugated diene and vinyl aromatic hydrocarbon, the content of vinyl aromatic hydrocarbon in the charged monomer mixture is 3 to 50% by weight, preferably 5 to 40% by weight.
% By weight.

The polymerization reaction is carried out by contacting the monomer in the liquid phase with the catalyst, but it is usually preferred to operate at a pressure sufficient to essentially maintain the liquid phase.
In addition, it is preferable to exclude substances interfering with the catalytic action from all the above substances charged into the reaction system.

After the reaction is completed, steam is blown into the polymer solution to remove the solvent, or a poor solvent such as methanol is added to coagulate the polymer, and then dried on a hot roll or under reduced pressure to form the polymer. Obtainable. Alternatively, the polymer solution can be obtained by directly removing the solvent from the polymer solution on a hot roll or under reduced pressure.

The polymer of the present invention is a polymer containing a high molecular weight polymer containing a metal-carbon bond chain, and is a homopolymer of a conjugated diene or a vinyl aromatic hydrocarbon, a conjugated diene and a vinyl aromatic hydrocarbon. And a mixture of both polymers. Particularly useful is a high molecular weight polybutadiene or a butadiene-styrene copolymer, and the molecular weight of the high molecular weight polymer having a metal-carbon bond chain contained therein can be arbitrarily controlled depending on the application.

In the polymer of the present invention, the ratio of the high molecular weight polymer containing a metal-carbon bond chain to the polymer not containing a metal-carbon bond chain in the whole polymer is preferably 50% or more. If it is less than 50%, a sufficient effect cannot be expected in the low hysteresis loss property.

Taking polybutadiene or a butadiene-styrene copolymer as an example, the butadiene portion has a microstructure (cis-1,4, trans-1,4, vinyl), and a copolymer is butadiene / styrene. Composition, its composition distribution (random structure, block structure or mixed structure)
Can easily obtain a polymer having a molecular structure freely selected according to the purpose, and can be applied to various uses.

The butadiene-styrene copolymer of the present invention may be used alone or in a blend with a natural rubber or a synthetic rubber,
If necessary, extend the oil and add the usual compounding agents for vulcanized rubber,
Vulcanized and started tire applications such as tire tread, undertread, carcass, sidewall, beat part,
It is used for anti-vibration rubber, belts, hoses, and other industrial products, and is particularly preferably used as rubber for tire treads.

[0048]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

In Examples, parts and% mean parts by weight and% by weight, unless otherwise specified.

Various measurements were made by the following methods. The number average molecular weight of the polymer was measured by gel permeation chromatography (GPC) equipped with a differential refractometer, and was calculated in terms of polystyrene using monodisperse polystyrene as a standard.

As an index of polymer processability, the polymer blend was subjected to roll winding on a 3-inch roll at 50 ° C., and the windability of the roll was visually evaluated.

Tan δ was used as an index of hysteresis loss in the polymer vulcanizate. The smaller tan δ,
It is evaluated as low hysteresis loss. The tan δ was measured using a viscoelasticity measuring device (manufactured by Rheometrics) at a temperature of 50 ° C., a strain of 1% and a frequency of 15 Hz.
The tensile properties were measured according to JIS K6301.

In this embodiment, the structural formula (RMX) is
_{As the} halogenated organometallic compound represented by _n , an organotin compound which is cyclohexyltin chloride represented by the following formula was used.

[0054]

[Chemical 4]

Various methods are generally conceivable for producing the organotin compound represented by the structural formula (RSnX) _n . As a concrete method, as shown in the following formula in the review by Robert K. Ingham et al., Chemical Reviews, Volume 60, page 517 (1960), (1)
Examples thereof include a reaction between a Grignard reagent and stannous chloride (2) a reaction between organolithium and a tin dihalide (3) a reaction between RSnX ₃ and an alkali metal.

[0056]

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The cyclohexyl tin chloride used in this example was synthesized by the method of the above formula (1). Specifically, stannous chloride (SnCl ₂ ) in an argon atmosphere
A 0.1 mol / tetrahydrofuran (THF) 60 ml solution was placed in a glass container, and cyclohexylmagnesium chloride 0.1 mol / THF solution 50 ml was slowly added dropwise to carry out the reaction with stirring at 0 ° C. for 5 hours. This reaction can be similarly performed at room temperature. After the reaction, it was treated with cyclohexane to remove the magnesium salt.

[Example 1] Cyclohexane 2 was placed in a 5 liter autoclave equipped with a stirrer, which had been dried and purged with nitrogen.
800 g, 1,3-butadiene 400 g, styrene 10
After adding 0 g and 12.5 g of THF and adjusting the internal temperature of the autoclave to 20 ° C., n-butyllithium 5.8 m
Mol was added to initiate polymerization. After about 10 minutes, 2.9 mmol of cyclohexyl tin chloride obtained by the above method was added when the polymerization addition rate was 23%, and the polymerization was further continued. About 10 minutes after the polymerization system reached the maximum temperature, 0.5 mmol of 2-propyl alcohol was added to terminate the polymerization. 4-Methyl-
5 g of 2,6-di-tert-butylphenol was added and thoroughly stirred. Steam was introduced into the obtained polymer solution to remove the solvent, and then hot air at 60 ° C. was applied for 8 hours to dry.

The molecular weight of the obtained polymer and the acid decomposition product obtained by treating the polymer with hydrochloric acid were measured by GPC. In addition, the amount of bound styrene and the amount of vinyl bond in the butadiene portion were measured using FTIR (Morero method). The results are shown in Table 1.
It was shown to.

Further, the obtained polymer was kneaded and blended according to the formulation shown in Table 3 to evaluate the workability (rolling property), and this blend was vulcanized at 145 ° C. for 33 minutes. Table 2 shows the evaluation results of the processability and vulcanized physical properties of the blends.

Example 2 The amount of THF charged was 15.
1 g, the amount of n-butyllithium added is 3.5 mmol,
Addition amount of cyclohexyl tin chloride is 1.7 mmol
A polymer was obtained in the same manner as in Example 1 except that cyclohexyl tin chloride was charged 42 minutes after the initiation of the polymerization and the polymerization addition rate was 93%. The properties of the polymer, the processability of the blend and the physical properties of the vulcanizate were measured in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

[Comparative Example 1] Cyclohexane 2 was placed in a dry, nitrogen-substituted 5 liter autoclave with a stirrer.
800 g, 1,3-butadiene 400 g, styrene 10
After adding 0 g and 15.6 g of THF and adjusting the temperature in the autoclave to 20 ° C., n-butyllithium 3.6 m
Mol was added to initiate polymerization. About 10 minutes after the maximum temperature of the polymerization system was reached, tributyltin chloride was added to 3.
6 mmol was added and stirred for 30 minutes, and 0.5 mmol of 2-propyl alcohol was added to terminate the polymerization. This was used as a polymer solution 1, 1 part was taken out from the polymerization container and dried in a vacuum drier, and the molecular weight, bound styrene amount and vinyl amount of the obtained polymer were measured in the same manner as in Example 1. The results are shown in Table 1.

Further, 1000 g of the polymer solution 1 was taken, and 4-methyl-2,6-di- was added to this as an oxidation stabilizer.
1.5 g of tert-butylphenol was added and stirred sufficiently. Steam was introduced into the obtained polymer solution to remove the solvent, and then hot air at 60 ° C. was applied for 8 hours to dry. The properties of the polymer, the processability of the blend and the physical properties of the vulcanizate were measured in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Comparative Example 2 The amount of THF charged was 10
8.2 g, the amount of n-butyllithium added was 25 mmol
And 10 minutes after the polymerization system reached the maximum temperature, 2-
A polymer solution was obtained in the same manner as in Comparative Example 1 except that 0.5 mmol of propyl alcohol was added to terminate the polymerization, and this was used as Polymer Solution 2 and obtained in the same manner as Polymer Solution 1. The molecular weight, bound styrene content, and vinyl content of the obtained polymer were measured in the same manner as in Example 1. The results are shown in Table 1.

10% of the polymer solution 1 obtained in Comparative Example 1 was used.
00 g, 300 g of the polymer solution 2 were mixed and further mixed with 4-methyl-2,6-di-tert as an oxidation stabilizer.
-Butylphenol 2g was added and stirred sufficiently. Thereafter, the same procedure as in Comparative Example 1 was performed, and the results are shown in Tables 1 and 2.

Comparative Example 3 2000 g of the polymer solution 1 obtained in Comparative Example 1 and 150 g of the polymer solution 2 obtained in Comparative Example 2 were mixed, and further 4-methyl-2, as an oxidation stabilizer, The same procedure as in Comparative Example 2 was carried out except that 3.3 g of 6-di-tert-butylphenol was added, and the results are shown in Tables 1 and 2.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

[Table 3]

As shown in Tables 1 and 2, butadiene-
Example 1 in which the halogenated organotin compound of the present invention was added at the initial stage of styrene copolymerization and Example 2 in which the halogenated organotin compound of the present invention was added at the final stage of butadiene-styrene copolymerization were stretched and stretched. The polymer exhibited excellent values in tenacity, tan δ, and roll wrapping property, and was a polymer that was balanced at a high level in terms of workability, breaking properties, low hysteresis loss, and the like. On the other hand, Comparative Example 1 in which a tin modifier, tributyltin chloride, was added in place of this compound was insufficient in terms of elongation, workability, and fracture characteristics, and butadiene-polymerized with only a lithium initiator was used. Comparative Examples 2 and 3 mixed with styrene copolymerization
Was excellent in workability, but was inferior in terms of low hysteresis loss.

A model diagram showing the synthetic scheme of the polymer of Example 1 and the state of the polymer chain cleaved after the treatment with hydrochloric acid is shown in FIG. The low molecular weight polymer (A) is about 3 × 10
^It has a number average molecular weight of ⁴ . By adding cyclohexyl tin chloride (B) to this, a coupling reaction occurs and a tin-carbon bonded chain-containing low molecular weight polymer (C) is produced. This polymer (C) further undergoes a coupling reaction with the polymer (A), and finally a tin-carbon bond chain-containing low molecular weight polymer (D) having two polymerization chains is produced. Since this (D) has a polymerization initiation ability by Sn-Li, the polymerization of the monomer continues, the chain grows, and the tin-carbon bond chain-containing high molecular weight polymer (E) is obtained. When this is treated with hydrochloric acid to break the tin-carbon bond, the low molecular weight polymer chain (P) resulting from the low molecular weight polymer (A) and the polymer (D) to the polymer (E) A high molecular weight polymerized chain (P ') in which the chain grows is obtained. FIG. 1 shows the above.

All the polymers obtained in Examples 1 and 2 and all the polymers were treated with hydrochloric acid (HCl) to undergo acid decomposition to break the bond between carbon and tin (Sn), and to give a low molecular weight chain and a high molecular weight chain. GPC was measured as described above for those separated from the molecular weight chain. The results are shown in FIGS. 2 and 3. FIG. 2 shows the first embodiment.
4 is a graph showing GPC curves of all the polymers obtained in Example 1 and polymers after acid decomposition treatment, and FIG. 3 is a graph showing GPC curves of all the polymers obtained in Example 2 and polymers after acid decomposition treatment Is.

In the GPC curves shown in FIGS. 2 and 3, all the polymers including the tin-carbon bond chain-containing high molecular weight polymer (E) obtained in Examples 1 and 2 are represented by a solid line, and the total weight is shown. The combined acid decomposition product is represented by a broken line.

As is clear from the solid GPC curve, all polymers have a major peak A and peak B. The main large peak A shows the polymer (E) obtained by the method of the present invention, and the small peak B shows the component corresponding to the component deactivated by the impurities contained in the cyclohexyl tin chloride in a trace amount.

Further, when this polymer was decomposed by treatment with hydrochloric acid, peak C was observed, as is apparent from the GPC curve of the broken line.
And a peak D. Peak C represents a low molecular weight polymerized chain (P) produced by breaking the tin-carbon bond,
This low molecular weight polymerized chain (P) is a chain initiated with n-butyllithium and grown before the introduction of cyclohexyltin chloride. Peak D represents a high-molecular weight polymerized chain (P ') produced by breaking the tin-carbon bond, and can be interpreted as a polymerized chain grown after adding cyclohexyltin chloride.

As shown in FIG. 1, assuming that the number average molecular weights of peak A, peak B and peak D are Mn (peak A), Mn (peak B) and Mn (peak D), Mn (peak A) = The relationship of Mn (peak B) × 2 + Mn (peak D) is established, and the component ratio of peak C of the acid decomposition product is considered to be the polymerization addition rate itself when cyclohexyl tin chloride is added.

The physical property values shown in Table 1 sufficiently support the above theoretical values, that is, the principle of the present invention and the explanation of FIG. 1, and the polymer obtained by the method of Example 1 of the present invention is
It can be considered that the polymer mainly contains a tin-carbon bond chain-containing high molecular weight polymer (E) having a structure in which two low molecular weight chains (P) and a high molecular weight chain (P ′) are bonded via tin.

On the other hand, the case of Example 2 in which cyclohexyl tin chloride is added after the polymerization addition rate reaches 93% will be considered with reference to FIG. 1 above. The molecular weight of the two polymerized chains (P) bonded to tin after charging was larger than that of the polymerized chain (P) in Example 1, and the polymerized chain (P) growing at the active lithium terminal after the cyclohexyltin chloride was charged. The molecular weight of ') becomes smaller than that of the polymerized chain (P') in Example 1. Therefore, the copolymer of Example 2 has two polymerization chains (P) involved in low hysteresis loss and one low molecular weight polymerization chain (P ′) contributing to processability. Here, since the two polymerized chains (P) involved in the low hysteresis loss property each have a low molecular weight by themselves as compared with the high molecular weight chain (P ′) involved in the low hysteresis loss property in Example 1, This copolymer having only one low molecular weight polymerized chain (P ') contributing to processability also has good processability, and the polymerized chain (P) involved in low hysteresis loss property is Although it has a low molecular weight as compared with the high molecular weight chain (P ′) in Example 1, it has two polymerized chains (P) in one molecule, so that a low hysteresis loss property and processability are well balanced. It can be said that the effects of the invention can be exhibited.

When a rubber composition is produced, carbon black, stearic acid, etc. are blended with a polymer as a rubber raw material, and kneading with low shearing force is performed under heating conditions. It is known that the tin-carbon bond of polymer (E) is cleaved. Therefore, as is clear from the physical properties of the vulcanizates of Examples 1 and 2, even in practical compounding and kneading, the effective tin-carbon bond as observed with the acid decomposed products of Examples 1 and 2 was obtained. It was presumed that the cleavage of the compound would occur, and it was confirmed that the effect that the low molecular weight chain contributes to the processability and that the cleavage of the high molecular weight chain contributes to the low hysteresis loss property is also exhibited in the rubber composition.

[0080]

Since the method for producing a polymer of the present invention has the above constitution, it has an excellent effect that a polymer having excellent processability and a small hysteresis loss can be obtained with high productivity.

[Brief description of drawings]

FIG. 1 is a model diagram showing a synthetic scheme of a polymer of Example 1 and a state of a polymer chain cleaved after acid decomposition treatment.

FIG. 2 is a graph showing GPC curves of all the polymers obtained in Example 1 and the polymer after acid decomposition treatment.

FIG. 3 is a graph showing GPC curves of all polymers obtained in Example 2 and polymers after acid decomposition treatment.

Claims (5)

[Claims] 1. Polymerization of a conjugated diene and / or a vinyl aromatic hydrocarbon in a hydrocarbon solvent using an organolithium compound as an initiator, and the polymerization chain growth is carried out immediately after the initiation of polymerization and before the termination of the polymerization. A method for producing a polymer, which comprises adding a halogenated organometallic compound represented by the following general formula to a terminal lithium-forming polymerization system to carry out a polymerization reaction. Embedded image (In the formula, M represents a metal selected from tin, silicon, germanium and lead, R represents an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 30 carbon atoms, X represents chlorine, bromine and Represents a halogen atom selected from iodine, and n represents an integer of 1 or more.) 2. The addition amount of the halogenated organometallic compound is 0.2 mol equivalent or more and less than 1 mol equivalent as a metal with respect to 1 mol of the polymerization chain growing terminal lithium. 1. The method for producing the polymer according to 1. 3. The addition amount of the halogenated organometallic compound is 0.3 mol equivalent or more and 0.5 mol equivalent or less as a metal with respect to 1 mol of the polymerization chain growing terminal lithium. The method for producing the polymer according to claim 1. 4. The method for producing a polymer according to claim 1, wherein the conjugated diene and / or the vinyl aromatic hydrocarbon are 1,3-butadiene and styrene, respectively. 5. The method for producing a polymer according to claim 1, wherein the halogenated organometallic compound is organotin chloride.