JP3442326B2 - Method for producing conjugated diene polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the production of a conjugated diene polymer, in which a specific post-treatment is carried out in a specific order, and a small amount of a phenolic antioxidant and an antioxidant having a specific chemical structure are used in combination. By doing so, it relates to a method for producing a conjugated diene polymer having improved high temperature stability, hue and processing stability.

[0002]

2. Description of the Related Art A conjugated diene polymer is a polymer obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer in an organic solvent using organolithium as an initiator. , Which has the characteristics of thermoplastic elastomer at room temperature,
When processed at high temperatures, by satisfying the same processing characteristics as thermoplastic resins, such as high temperature thermal stability and hue, plastic modification, asphalt, adhesive / adhesive fields, food packaging containers or industrial rubber. It is used in fields. However, since this conjugated diene copolymer is inferior in high temperature stability, there is a problem that the hue of the polymer is deteriorated, a molded product is yellowed, and the processing stability is not good. Several attempts have been made to improve the drawbacks of the conjugated diene polymer. For example, in Japanese Examined Patent Publication No. 55-7459, styrene obtained by polymerizing a conjugated diene monomer and a vinyl aromatic monomer with an organic lithium as an initiator in an organic solvent, a butadiene block polymer solution, After stopping the polymerization reaction with methanol and before carrying out the devolatilization step, an aqueous solution of an organic acid is added to the polymer solution and mixed by contact, and then the oil phase-water phase is separated, followed by the devolatilization step. It is described that a conjugated diene polymer having a good hue can be produced by recovering the polymer by. Further, JP-A-60-231717 discloses that a living polymer (living polymer) obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer using an organic lithium as an initiator. It is disclosed that a polymer having an improved hue was obtained by adding a stabilizer, or a stabilizer and a terminating agent, and then removing the solvent and adding a fatty acid having 10 or more carbon atoms. Furthermore, in JP-A-62-232402, the living polymer is a polymer of the polymer even if the solvent is devolatilized after adding the organic acid and the stabilizer in the substantial absence of water. It is described that the color tone can be improved. In addition, JP-A-4-25
JP 2243 discloses that gelation can be prevented by blending two kinds of specific stabilizers with respect to the conjugated diene rubber, for example, a phenolic stabilizer and a thiophenolic stabilizer. Therefore, it is necessary to increase the amount of the phenolic stabilizer added, which adversely affects the initial hue of the rubber, and the content of the phenolic antioxidant in the graft copolymerization reaction in the production of the rubber-modified vinyl aromatic resin. The use of a conjugated diene rubber having a high ratio adversely affects the conversion rate of the monomer and the graft rate of the graft copolymer, resulting in a problem that the physical properties of the rubber-modified vinyl aromatic resin are deteriorated.

[0003]

Although the above-mentioned prior art can improve the drawbacks such as the hue of the conjugated diene polymer, the effects are limited, and the improvement of the heat stability, the hue and the processing stability, etc., especially at high temperature is not improved. Not enough. Moreover, in the above-mentioned prior art, in order to satisfy the requirements such as hue and thermal stability, it is necessary to add a phenolic antioxidant at a high concentration, so that the initial hue of the rubber or the polymerization reaction of the rubber-modified vinyl aromatic resin Have a bad effect on. As a result of research to solve the above-mentioned drawbacks, the present inventors have found a method for producing a conjugated diene-based polymer having extremely good high-temperature stability, processing stability, and hue, and arrived at the present invention. Is.

That is, the method for producing a conjugated diene polymer according to the present invention comprises a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer as main components, and starts an organolithium compound in an organic solvent. A living polymer obtained by polymerizing as an agent is used, and the living polymer is prepared according to the following (1)
By performing post-treatment in the order from the step to the step (3) and then devolatilizing the obtained polymer solution to recover the polymer, excellent high temperature stability, hue and processing stability can be obtained. It is characterized by obtaining a conjugated diene polymer having: (1) 0.01 to 1 organic acid per 100 parts by weight of living polymer.
Parts by weight, (2) at least 1 part by weight of water is added to 100 parts by weight of the living polymer, and (3) 100 parts by weight of the living polymer, and (a) a phenolic antioxidant is added.
(b) The following general formula (I)

[0005]

[Chemical 2]

(Wherein R ₁ and R ₃ are —CH ₂ —S—R ₅ , R ₅ is alkyl having 20 or less carbon atoms, and R ₂ and R ₄ are hydrogen or alkyl having 15 or less carbon atoms. ) Add a total of 0.02 to 0.5 parts by weight of the antioxidant. The living polymer used in the present invention uses an organolithium as an initiator and polymerizes a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer in the presence of an organic solvent, preferably a hydrocarbon solvent. Can be obtained. When the conjugated diene monomer is polymerized alone, a conjugated diene polymer containing two types, a star type and a linear type, is obtained. Usually, when organolithium is used as the initiator, the conjugated diene polymer is low-cis. Its structure is typical composition range of cis-vinyl is 30% -40% / 5%-
40% and 5% by weight styrene solution viscosity is 5 ~ 400cps
Is. The above manufacturing method is USP 2,975,160, USP 3,094,51
4, USP 3,135,716, USP 3,244,664, USP 3,318,86
2, JP-B-48-875, JP-B-48-46691, JP-B-49-36957, JP-A-55-40734, JP-A-57
This is a known method described in Japanese Patent Publication No. 40513/405. In addition,
The living polymer targeted by the present invention can also be produced by copolymerizing a conjugated diene monomer and a vinyl aromatic monomer. Such living copolymers are also USP 3,094,514, USP
3,451,988, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17979
JP, JP-B-46-32415, JP-B-49-36957, JP-B-48-2423, JP-B-48-4106, JP-B-56-28925, JP-B-51-49567 It is a known one described in. The ratio of the amount of the conjugated diene monomer and the vinyl aromatic monomer used for producing the living copolymer is not particularly limited, and is generally 99.9 / 0.1 to 0.1 / 99.
9, preferably in the range of 98/2 to 2/98, and may be a random copolymer, a star type copolymer, a block copolymer, or a taper copolymer. When the living polymer is a block polymer, the content of the vinyl aromatic monomer in the polymer is preferably 60% by weight or less, particularly 55% by weight or less, in order to exhibit the characteristics of the thermoplastic elastomer. Further, in order to exhibit the characteristics of the thermoplastic resin, the content of the vinyl aromatic monomer in the polymer is 65% by weight or more. The conjugated diene-based monomer used in the present invention is a diolefin having a pair of double bonds, for example, 1,3-butadiene, 2-methyl-1,3-butadiene, 2-methyl-1,3. -Isopentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-isopentadiene, 1,3-hexadiene is selected from one kind or two or more kinds, and among them, 1,3-butadiene or 1 1,3-isopentadiene is preferred. As the vinyl aromatic monomer used in the present invention, styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene,
There is α-methylstyrene and the like, and one or more of them are used. As the organic solvent in the present invention, a hydrocarbon solvent is preferable, and aliphatic hydrocarbons such as butane, pentane, n-hexane, isopentane, heptane, octane and isooctane, cyclopentane, methyl-cyclopentane, cyclohexane, methyl-cyclohexane. , Alicyclic hydrocarbons such as ethyl-cyclohexane, and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene, and any one of them may be used alone or in combination. . The organolithium compound used as a suitable initiator in the present invention is
Compounds containing one or more lithium atoms in the molecule, such as ethyl lithium, n-propyl lithium,
Isopropyl lithium, n-butyl lithium, secondary butyl lithium, hexyl lithium, cyclohexyl lithium, phenyl lithium, phenyl methyl lithium, naphthyl lithium, tertiary butyl lithium, trimethylene dilithium, tetramethylene dilithium, butadiene dilithium, And isoprenyldilithium, etc.
It is a mixture of 1 or 2 or more. In the method for producing a conjugated diene polymer of the present invention, the polymerization rate when polymerizing the polymer, the microstructure of the polymer [cis, trans, vinyl group ratio], the conjugated diene monomer to vinyl aroma The reaction ratio of the group monomer can be adjusted with a polar compound or a randomizing agent. Examples of the polar compound or randomizing agent include ethers, amines, thioethers, phosphoramides, alkylbenzenes, sulfonic acids, potassium or sodium alkoxides, and the like. Specific examples suitable for the present invention are as follows: (a) Ethers include dimethyl ether, diethyl ether, dibutyl ether, diphenyl ether,
Tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, bisdiethylene glycol ethyl ether, bisdiethylene glycol butyl ether, bisphenyl ether and the like can be mentioned.

(B) As amines, tertiary amines,
Examples thereof include trimethylamine, triethylamine, tripropylamine, tributylamine, tetramethylethylenediamine, diethylbenzamine, pyridine, and cyclic tertiary amine.

Examples of (c) phosphine or phosphoramide include triphenylphosphine and hexamethylphosphoramide.

Examples of (d) potassium or sodium salts of alkyl oxides include potassium butoxide. Suitable examples of polyfunctional coupling agents that can be added following polymerization in the present invention include di- or multivinylaromatic compoun.
ds), di- or multiepoxide
s), di- or multiisocya
nates), di- or multiimines,
Di- or multialdehydes, di- or multialdehydes
-Or multiketones, di- or multihalides, especially silicone halides and halosilanes, and mono-, di-, or multianhydrides , Mono-, di-, or multiesters, etc., and two or more of them, or a combination type in which they are mixed may be used. Specific examples of the di- or multivinyl aromatic compound coupling agent,
Divinylbenzene, 1,2,4-trivinylbenzene (1,2,4-trivinylbenzene), 1,3-divinylnaphthalene (1,3-divinylnaphthalene), 1,3,5-trivinylnaphthalene (1 , 3,5-trivinylnaphthalene), 2,4-divinylbiphenyl (2,4-divinylbiphenyl), and analogs thereof, among which divinyl aromatic hydrocarbon is preferable,
In particular, isomers of ortho, meta, para, etc. selected from divinylbenzene are more preferable. Three types of isomer
Good results have been obtained when commercialized divinylbenzene obtained by mixing the above with other compounds is used. The above
Also suitable as multiepoxides are, for example, epoxidized polybutadiene solutions, epoxidized vegetable oils, epoxides and the like. Examples of the epoxidized vegetable oil include epoxidized soybean oil and epoxidized linseed oil. An example of the above multi-isocyanate is benzene-1,2,4
-Triisocyanate (bezene-1,2,4-triisocyanate),
Naphthalene-1,2,5,7-tetraisocyanate
e-1,2,5,7-tetraisocyanate) and their analogs, and the multiimine can be a known multiaziridine compound, that is, a compound containing three or many aziridine rings in one molecule, such as tri- Aziridinylphosphine oxide or sulfide, specifically tri (1-aziridinyl) phosphine oxide
ne oxide], tri (2-methyl-1-aziridinyl) phosphine oxid
e], tri (2-ethyl-3-decyl-1-aziridinyl) phosphine sulfide [tri (2-ethyl-3-decyl-1-aziridinyl) phos
phinesulfide], and the like. A typical example of the above-mentioned multialdehyde is 1,4,7-naphthalene tricarboxyaldehyde (1,4,7-naphthalene tricarboxyal
dehyde), 1,7,9-anthracentricarboxyaldehyde (1,7,9-anthracenetricarboxyaldehyde), 1,1,5-pentanetricarboxaldehyde (1,1,5-pentanetricarbo)
xyaldehyde), multi-aldehyde-containing aliphatic or aromatic compounds. Typical examples of multiketones are 1,
4,9,10-anthracene tron (1,4,9,10-anthracenetet
rone), 2,3-diactonylcyclohexanone (2,3-diacet
onylcyclohexanone), and the like. Examples of multi-anhydrides include pyromellitic anhydride
tic dianhydride), styrene-maleic anhydride copolymer
(Styrene-maleic anhydride copolymers) and similar substances. Also, multi-esters include, for example, diethyl-adipate, triethyl citrate.
lcitrate), 1,3,5-tricarbethoxybenzene (1,3,5-
tricarbethoxybenzene), and the like. Examples of the multihalide include halogen silanes such as silicon tetrachloride, silicon tetrabromide, silicon tetrahalides such as silicon tetraiodide, trifluorosilane, trichlorosilane, trichloroethylsilane, and tribromobenzylsilane. Such as silicon trihalides, and the like, or hydrocarbons substituted with multiple halogens such as 1,3,5-tri (bromomethyl) benzene and 2,5,6,9-tetrachloro-
It is selected from 3,7-decadiene. In those compounds, the halogen is attached to the alpha carbon atom of the active group such as an ether bond, a carbonyl group, or a carbon-carbon double bond. The method for producing a polymer according to the present invention, the polymerization temperature is generally −40 to 150 ° C., preferably 40 to 120 ° C., the polymerization time varies depending on the polymerization conditions, usually within 48 hours, preferably 0.5 to 10 hours. Is. Impurities during polymerization,
For example, it is necessary to prevent contamination with water, acid, carbon dioxide, etc., and the weight average molecular weight of the polymer is generally
5,000 to 5,000,000, especially 10,000 to 1,000,000 are more preferable.

In the present invention, a living polymer obtained by polymerizing the above-mentioned polymerization components under the above-mentioned conditions is subjected to post-treatment in the order of the following steps (1) to (3), and thereafter, By subjecting the obtained polymer solution to the steps of devolatilization and recovery, a desired conjugated diene polymer is obtained; (1) 0.01 to 1 of an organic acid relative to 100 parts by weight of the living polymer.
Parts by weight, (2) at least 1 part by weight of water is added to 100 parts by weight of the living polymer, (3) 100 parts by weight of the living polymer, and (a) a phenolic antioxidant and (b) The following general formula (I)

[0011]

[Chemical 3]

(Wherein R ₁ and R ₃ are —CH ₂ —S—R ₅ and R ₅ are alkyl having 20 or less carbon atoms, and R ₂ and R ₄ are hydrogen or alkyl having 15 or less carbon atoms. ). Add a total of 0.02 to 0.5 parts by weight of antioxidant. Here, the organic acid in the step (1) refers to an acidic organic compound, selected from compounds such as carboxylic acid, sulfonic acid, sulfinic acid, or phenol, preferably an organic compound having a carboxyl group, Examples include formic acid, acetic acid, pentanoic acid, octanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid,
Examples thereof include behenic acid and versatic acid, and among them, versatic acid is preferable. The method of adding the organic acid used in the present invention is also not particularly limited, and for convenience of work, it is preferable to dissolve the organic acid in a solvent and then add the polymer solution. On the other hand, for the stability of the polymer, the oxygen content of the added organic acid solution is preferably 100 ppm or less,
It is preferably 10 ppm or less, more preferably 1 ppm or less. The amount of the organic acid added is 0.01 to 1 part by weight, preferably 0.03 to 0.5 part by weight, based on 100 parts by weight of the living polymer. If the amount of the organic acid added is less than 0.01 part by weight, the hue of the polymer cannot be improved. On the contrary, if the amount added is more than 1 part by weight, the physical properties of the conjugated diene polymer, or the following processing / application When 1 part by weight or more of an organic acid is added to a batch-type conjugated diene polymerization reaction tank, the organic acid remains in the polymer, which affects the polymerization reaction of the next batch. The organic acid can also be used as a terminating agent for the polymerization reaction of the living polymer (that is, an inactivating agent for the polymerization active point). However, in order to achieve such an action, the addition amount must be accurately controlled, and an unsuitable amount reduces the thermal stability of the polymer, deteriorates the hue, and further affects the quality of the polymer. To do.

In the production method of the present invention, it is necessary to add a large amount of water in the step (2) after adding the organic acid in the step (1) of the post-treatment of the resulting living polymer. Is advantageous in that the reaction of a small amount of residual active end groups can be stopped, and unstable substances generated by the initiator reaction, such as lithium hydride and lithium chloride, are dissolved in water during the reaction, and Is easily removed, and the unstable substance does not adversely affect the hue, thermal stability, transparency and the like of the conjugated diene polymer. The amount of water used in the step (2) of the post-treatment of the production method according to the present invention is 1 part by weight or more, preferably 2 to 50 parts by weight, particularly 3 to 20 parts by weight based on 100 parts by weight of the living polymer. Parts are more preferred. The addition of water in the step (2) may be carried out either in the polymerization reaction tank, in the outlet line of the reaction tank, or in the intermediate storage tank, from the viewpoint of work convenience and quality stability. More preferably, it is added into the outlet line of the reaction tank. Although not particularly limited, it is preferable to use pure water for quality stability. The antioxidant added in the step (3) of the post-treatment in the production method of the present invention can be divided into two types, a and b.

(A) is a phenolic antioxidant, which is selected from commonly used phenolic antioxidants. As a specific example, tetra [methylene-3- (3 ',
5'-di-tert-butyl-4-oxyphenyl) propionate] methane, 1,3,5-tri-methyl-2,4,6-tri- (3,5-di-tert-butyl-4 -Oxyphenyl) benzene, 2,6-di-tert-butyl-4-methylphenol, 2,4-bis-n-sulfooctyl-6- (4-hydroxy-3,5-di-tert-butyl -Phenylamino) -1,3,5-triazine, octadecyl-3- (3,5-di
-Tertiary butyl-4-oxyphenyl) propionate, triglycol-bis- [3- (3-tertiarybutyl-5-methyl-4-oxyphenyl)] propionate, 1,3,5-tri- ( 4-tertiary butyl-3-hydroxy-2,6-dimethylphenyl) isocyanic acid, 2,2'-methylene-bis- (4-methyl-6-tertiary butylphenol), 3,9-bis- { 2-[(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-
Dimethylethyl} -2,4,8,10-tetra-ethanedioyl [5,
5] Undecane, 4-hydroxymethyl-2,6-di-tertiary butylphenol, 2,6-di-tertiary butyl-4-ethylphenol, butylated-hydroxy-phenyl methyl ether, 2,
2'-di-hydroxy-3,3'-dicyclohexyl-5,5-dimethyl-diphenylmethane, 1,1,3-tri (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4, 4'-butylene-
Bis (6-tert-butyl-m-methylphenol), bis- (3-
Cyclohexyl-2-hydroxy-5-methylphenyl) methane, 2,2-methylene-bis (4-ethyl-6-tert-butylphenol), and 1,1-bis (2'-methyl-4'-hydroxy) -Five'-
Tert-butylphenol) and the like, and among them, octadecyl-3- (3,5-di-tertiarybutyl-4-oxyphenyl) propionate is more preferable. The phenolic antioxidant (a) used in the present invention does not include the thiophenolic antioxidant (b) represented by the following formula (I).

(B) is a thiophenol antioxidant represented by the formula (I),

[0016]

[Chemical 4]

In the formula, R ₁ and R ₃ are —CH ₂ —S—R ₅ , R ₅ is alkyl having 20 or less carbon atoms, R ₂ and R ₄ are hydrogen, and the carbon number is
An alkyl of 15 or less, and specific examples include 2,4-bis
(n-octylthiomethyl) -6-methylphenol, 2,4-bis (2 ', 3'-di-hydroxypropylthiomethyl) -3,6-dimethylphenol, 2,4-bis (2'-acetyl Oxyethylthiomethyl) -3,6-dimethylphenol, 4,6-bis (octylthiomethyl) -o-methylphenol, and the like, among which 4,6-bis (octylthiomethyl) -o-methylphenol is More preferable. Antioxidant used in the present invention
The total amount of the two kinds of (a) and (b) is 0.02 to 0.5 parts by weight, preferably 0.02 to 0.3 parts by weight, and more preferably 0.02 to 0.21 parts by weight, based on 100 parts by weight of the living polymer. so,
The amount of the antioxidant (a) used is 0.01 to 0.18 part by weight, preferably 0.01 to 0.09 part by weight. The amount of the antioxidant (b) used is 0.01 to 0.32 part by weight, preferably 0.01 to 0.21 part by weight, more preferably 0.01 to 0.12 part by weight. Antioxidant (a)
And the total amount of antioxidant (b) exceeds 0.5 parts by weight,
Alternatively, when the amount of the antioxidant (b) used exceeds 0.32 parts by weight, the initial hue of the polymer is adversely affected. On the other hand, if the total amount of the antioxidant (a) and the antioxidant (b) is less than 0.02 parts by weight, or if the amount of the antioxidant (b) used is 0.01 parts by weight or less, the conjugated diene-based The hue, thermal stability, and processing stability of the polymer are also deteriorated. Other antioxidants may be phosphorus-based antioxidants, thioether-based antioxidants, and sterically hindered amine-based antioxidants, and the amount used is in the range of 0.01 to 0.5 parts by weight. The phosphorus-based antioxidant is a phosphorous acid ester-based antioxidant or a phosphoric acid-based ester-based antioxidant, and representative examples thereof include tris (nonylphenyl) phosphite, laurylphosphite, cycloneopentyltetrahydronaphthylbis.
(Octadecyl phosphite), 4,4'-butyl bis (3-
Methyl-6-tertiary butyl phenyl-bistridecanoyl phosphite), tris (2,4-tertiary butyl phenyl) phosphite, tetrakis (2,4-tertiary butyl phenyl)
4,4'-Biphenylene diphosphonate, 9,10-dihydro
-9-oxa-10-phosphaphenanthrene-10-oxide and the like can be mentioned. Typical examples of thioether antioxidants include dioctadecanoylthiodipropionate,
Dipalmityl thiodipropionate, pentaerythritol
-Ru-tetrakis- (β-lauryl-thiopropionate),
Examples include bislauryl thioether, bistridecyl thioether, bis tetradecyl thioether, and bis octadecyl thioether. According to the manufacturing method of the present invention,
Addition of a small amount of the antioxidant to the conjugated diene polymer, that is, 0.5 parts by weight or less of the total amount of the antioxidants (a) and (b), gives the copolymer sufficient thermal stability, good hue and processing. Can give sex. On the other hand, post-treatment steps (1), (2), (3)
The lack of any of the processing conditions, such as observing the order of, and adding organic acid in step (1), and adding 1 part by weight or more of water in step (2) is a good hue and color. It has a serious adverse effect on stability. In the post-treatment step (3) of the present invention, the additives may be directly added to the reaction tank, further stirred and mixed, or added to the pipeline and statically mixed. The treatment temperature is 0 to 120 ° C., preferably 50 to 100 ° C., and the time is several minutes to several hours. In the present invention, after the above post-treatment steps (1), (2) and (3), as a method for devolatilizing the solvent in the polymer solution, a known method is to evaporate the solvent by heating the polymer solution. How to remove, water to the polymer,
Alternatively, after adding heated water to disperse it, a vapor devolatilization method of further evaporating and removing the solvent with steam, or adding a large amount of a precipitating agent such as methanol to the polymer, and then depositing a polymer precipitate Method, a vacuum evaporation method of a polymer solution, a method of directly squeezing a solvent with an extruder provided with a devolatilizing port to devolatilize.

[0018]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited to these examples. <Test method> 1. Polymer Hue and Thermal Stability Test The polymer is compression molded into a 4 in x 4 in x 1/8 in sheet and the yellow index, or YI, is measured with a color difference meter. After heating the sheet in an oven at 200 ° C. for 30 minutes, the change in color tone is measured as thermal stability. In Table 1, ◎ Slightly yellow ○ Light yellow △ Deep yellow × Brown 2. Polymer stability test 60g of polymer was placed in a brabander measuring machine, 150 ℃ × 60rpm
Under the conditions described above, a curve diagram of torque and time is recorded to obtain the induction time of the gel. The longer the induction time, the better the processing stability of the polymer. <Preparation Example> (Preparation of Living Polymer A) After cleaning a 200 liter reactor with nitrogen gas, 13 Kg of butadiene and 6 g of tetrahydrofuran were added to 100 Kg of n-hexane solvent and mixed, and then n- Butyllithium (5.5 g) was added, and the mixture was reacted at 55 ° C. for 1 hour, and silicon tetrachloride (SiCl ₄ ) (1.5 g) was added to obtain a star-type living polymer A. (Preparation of Living Polymer B) The linear type living polymer was prepared by the same manufacturing method as (Preparation of Living Polymer A) without changing the amount of n-butyllithium added to 7.5 g and using silicon tetrachloride. Got B. (Preparation of Living Polymer C) Similarly, a 200 liter reactor was flushed with nitrogen gas, 3.2 kg of styrene and 9.4 kg of butadiene were mixed with 110 kg of n-hexane solvent in the vessel, and then 11.4 g of tetrahydrofuran was added. Potassium butoxide
6.4 g of um butoxide), preheated at a temperature of 70 ° C., added 9.7 g of n-butyllithium and reacted for 1 hour, after which a linear type living polymer C (butadiene-styrene copolymer) was added. Got [Examples 1 to 6] Living polymer A obtained in the above preparation example,
Post-treatment was performed in the next step under the addition conditions of B and C shown in Table 1. That is, in step (1), an organic acid was added to the living polymer solution and mixed sufficiently. Step (2), water was added. In step (3), an antioxidant was added and mixed. The polymer was devolatilized in a steam stripping step and then dried to obtain a conjugated diene polymer. The physical property results are shown in Table 1. [Comparative Examples 1 to 6] The same operation method as in Example 1 was carried out by changing the types and amounts of the additives in steps (1), (2) and (3) as shown in Table 1. The physical property test results are shown in Table 1. As can be seen from the results of the above examples shown in Table 1, according to the order of steps (1), (2) and (3), an organic acid was added to the living polymer as a terminating agent, and water was also added as a terminating agent. Further, by adding an appropriate amount of antioxidant, a polymer having good hue and thermal stability and excellent processing stability can be obtained. On the other hand, from the results of the comparative example shown in Table 1, when the organic acid and water are not added in the steps (1) and (2), respectively, and when the amount of the antioxidant used is large, it is limited in the step (3). Hue, thermal stability and process stability even if the amount of antioxidants (a) and (b) prepared is not used according to the prescribed procedure or if the steps (1), (2) and (3) are not performed in the order specified. It can be seen that a polymer having good properties cannot be obtained.

[0019]

[Table 1]

(Note) 1. Vac is versatic acid 2. HLA is lauric acid 3. MeOH is methanol 4. a-1 is octadecyl-3- (3,5-di-tertiarybutyl-4-oxyphenyl) Propionate 5. a-2 is 2,6-di-tert-butyl-p-methylphenol 6. b is 4,6-bis (octylthiomethyl) -o-methylphenol

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 2001-131220 (JP, A) JP 9-255716 (JP, A) JP 62-215612 (JP, A) JP 4-246454 (JP, A) International Publication 98/29457 (WO, A1) International Publication 98/44034 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 6/00-6/28

Claims (5)

(57) [Claims] 1. A living polymer obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer in an organic solvent using an organolithium compound as an initiator, the following (1): A method for producing a conjugated diene polymer, characterized in that post-treatment is carried out in the order from the step to the step (3), and then the obtained polymer solution is volatilized to recover the polymer. 0.01 to 1 organic acid per 100 parts by weight of living polymer
(2) At least 1 part of water is added to 100 parts by weight of the living polymer.
(3) 100 parts by weight of the living polymer, (a) 0.01 to 0.18 parts by weight of a phenolic antioxidant, and (b) the following general formula (I): (Wherein R ₁ and R ₃ are —CH ₂ —S—R ₅ , R ₅ is alkyl having 20 or less carbon atoms, and R ₂ and R ₄ are hydrogen or alkyl having 15 or less carbon atoms) Antioxidant 0.01 to 0.32 weight
Add total 0.02-0.5 parts by weight of the parts. 2. The antioxidant added in the step (3) of the post-treatment is (a) 0.01 to 0.09 part by weight of a phenolic antioxidant and (b) 0.01 to 0.21 part by weight of the formula (I). 2. The method for producing a conjugated diene polymer according to claim 1, which comprises an antioxidant represented by the formula. 3. As a second step of the post-treatment, water 2 to 50 is used.
2. The method for producing a conjugated diene polymer according to claim 1, wherein a weight part is added. 4. The step (1) of the post-treatment, wherein the organic acid is versatic acid.
The method for producing the conjugated diene polymer as described in 1. 5. In the step (3) of the post-treatment, the formula
2. The method for producing a conjugated diene polymer according to claim 1, wherein the antioxidant represented by (I) is 4,6-bis- (octyl thiomethyl) -o-methylphenol.