JP2001048920A - Production of conjugated diene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a conjugated diene polymer which has improved high temperature stability, improved color tone and improved processing stability. SOLUTION: This method for producing a conjugated diene polymer comprises polymerizing a conjugated diene or the conjugated diene and a vinylic aromatic monomer in the presence of an organic lithium compound as a polymerization initiator in a hydrocarbon solvent, post-treating the obtained living polymer in the order of the below-mentioned processes (1), (2) and (3), and then subjecting the obtained polymer solution to an evaporation treatment to recover the polymer. (1) Adding 0. 01 to 1 pt.wt. of an organic acid to 100 pts.wt. of the living polymer, (2) adding at least 1 pt.wt. of water to 100 pts.wt. of the living polymer, and (3) adding (a) a phenolic antioxidant and (b) an antioxidant of the formula (R1 and R3 are each CH2-S-R5; R5 is a <=20C alkyl; R2 and R4 are each hydrogen or a <=15C alkyl) in a total amount of 0.02 to 0.5 pt.wt. per 100 pts.wt. of the living polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a conjugated diene polymer in which a specific post-treatment is performed in a specific order, and a small amount of a phenolic antioxidant and an antioxidant having a specific chemical structure are used in combination. The present invention 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 using an organic lithium as an initiator in an organic solvent. Has the properties of a thermoplastic elastomer at room temperature,
When processing at high temperatures, by satisfying the same processing characteristics as thermoplastic resins, such as high temperature thermal stability and color requirements, plastic modification, asphalt, adhesive / adhesive fields, food packaging containers or industrial rubber It is used in various fields. However, the conjugated diene copolymer is inferior in high-temperature stability, so that the color of the polymer is deteriorated, the molded article is yellowed, and the processing stability is not good. Several improvement methods have been attempted to improve the disadvantages of the conjugated diene polymer. For example, Japanese Patent Publication No. 55-7459 discloses a styrene / butadiene block polymer solution obtained by polymerizing a conjugated diene monomer and a vinyl aromatic monomer with an organic lithium in an organic solvent as an initiator. After stopping the polymerization reaction with methanol, before performing 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-aqueous phase is separated, and then the devolatilization step is performed. Describes that a conjugated diene polymer having a good hue can be produced by recovering the polymer. 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 with an organic lithium as an initiator. It discloses that a polymer having an improved hue was obtained by adding a stabilizer or a stabilizer and a terminator and then removing a solvent and adding a fatty acid having 10 or more carbon atoms. Further, in JP-A-62-232402, the living polymer is substantially free of water, after adding an organic acid and a stabilizer, and then devolatilizing the solvent, the It describes that the color tone can be improved. In addition, JP-A-4-25
No. 2243 discloses that gelling can be prevented by blending two types of specific stabilizers with respect to a conjugated diene rubber, for example, a phenol-based stabilizer and a thiophenol-based stabilizer. According to the report, it is necessary to increase the amount of the phenolic stabilizer, which adversely affects the initial hue of the rubber, and furthermore, the content of the phenolic antioxidant in the graft copolymerization reaction in the production of the rubber-modified vinyl aromatic resin. Use of a conjugated diene rubber having a high molecular weight adversely affects the conversion ratio of the monomer and the graft ratio of the graft copolymer, and causes a problem that the physical properties of the rubber-modified vinyl aromatic resin are deteriorated.

[0003]

The above prior art can improve the disadvantages such as the hue of the conjugated diene polymer, but the effect is limited. In particular, the improvement of the thermal stability at high temperature, the hue and the processing stability, etc. is not achieved. Not enough. In addition, in the prior art, a phenolic antioxidant needs to be added at a high concentration in order to satisfy requirements such as hue and thermal stability, so that the initial hue of rubber or the polymerization reaction of rubber-modified vinyl aromatic resin is required. Have a bad effect. The present inventors have studied to solve the above-mentioned drawbacks, and as a result, have found a method for producing a conjugated diene-based polymer having extremely good high-temperature stability, processing stability, and hue, and have reached the present invention. It 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 starting an organic lithium compound in an organic solvent. Using a living polymer obtained by polymerization as an agent, the living polymer is described in the following (1).
The post-treatment is carried out in the order from the step to the step (3), and then the obtained polymer solution is devolatilized to recover the polymer, so that excellent high-temperature stability, hue, and processing stability can be obtained. (1) Organic acid 0.01 to 1 with respect to 100 parts by weight of living polymer.
(2) 100 parts by weight of living polymer and at least 1 part by weight of water; (3) 100 parts by weight of living polymer, (a) phenolic antioxidant
(b) The following general formula (I)

[0005]

Embedded image

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. ) Is added in a total amount of 0.02 to 0.5 parts by weight of the antioxidant. The living polymer used in the present invention is obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and a vinyl aromatic monomer in the presence of an organic lithium, and an organic solvent, preferably a hydrocarbon solvent. Obtained. When a conjugated diene monomer is polymerized alone, a conjugated diene polymer containing two types, a star type and a linear type, is obtained. Usually, the conjugated diene polymer is low-cis, using organolithium as the initiator. It has a typical composition of cis / vinyl (cis-vinyl) from 30% to 40% / 5%
40%, and 5% by weight styrene solution viscosity is 5-400 cps
It is. The above production method is USP 2,975,160, USP 3,094,51
No. 4, USP 3,135,716, USP 3,244,664, USP 3,318,86
No. 2, JP-B-48-875, JP-B-48-46691, JP-B-49-36957, JP-A-55-40734, JP-A-57
It is a known method described in -40513 and the like. 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 copolymer is also USP 3,094,514, USP
3,451,988, JP-B-36-19286, JP-B-43-17979
JP, JP-B-46-32415, JP-B-49-36957, JP-B-48-2423, JP-B-48-4106, JP-B-56-28925, and JP-B-51-49567 Are well-known. The ratio of the amount of the conjugated diene monomer and the amount of 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 preferably 55% by weight or less, in order to exhibit the characteristics of the thermoplastic elastomer. In order to exhibit the characteristics of the thermoplastic resin, the content of the vinyl aromatic monomer in the polymer is set to 65% by weight or more. The conjugated diene 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 One or more selected from -isopentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-isopentadiene and 1,3-hexadiene, and among them, 1,3-butadiene or 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,
α-Methylstyrene and the like, one or more of which are used. As the organic solvent in the present invention, a hydrocarbon solvent is preferable, butane, pentane, n-hexane, isopentane, heptane, octane, aliphatic hydrocarbons such as isooctane, cyclopentane, methyl-cyclopentane, cyclohexane, methyl-cyclohexane , Selected from alicyclic hydrocarbons such as ethyl-cyclohexane, and aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene, either of which may be used alone or in combination of two or more. . The organolithium compound used as a suitable initiator in the present invention,
Compounds containing one or more lithium atoms in the molecule, for example, ethyl lithium, n-propyl lithium,
Isopropyl lithium, n-butyl lithium, secondary butyl lithium, hexyl lithium, cyclohexyl lithium, phenyl lithium, phenylmethyl lithium, naphthyl lithium, tertiary butyl lithium, trimethylene dilithium, tetramethylene dilithium, butadiene dilithium, And isoprenyl dilithium
One or a mixture of two or more. In the method for producing a conjugated diene polymer according to the present invention, the polymerization rate at the time of polymerizing the polymer, the micro structure of the polymer [ratio of cis, trans, and vinyl groups], the conjugated diene monomer versus vinyl aromatic The reaction ratio of the group monomer can be adjusted with a polar compound or a randomizing agent. Examples of the polar compound or the 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) As ethers, dimethyl ether, diethyl ether, dibutyl ether, diphenyl ether,
Examples thereof include tetrahydrofuran, diethyleneglycol dimethyl ether, diethylene glycol dibutyl ether, bisdiethylene glycol ethyl ether, bisdiethylene glycol butyl ether, and bisphenyl ether.

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

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

(D) Examples of the potassium or sodium salts of the alkyl oxide include potassium butoxide. Preferable examples of the polyfunctional coupling agent that can be added after the 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 multi-ketones, di- or multihalides, especially silicone halides and halosilanes, and mono-, di-, or multianhydrides , Mono-, di-, or multiesters, and two or more of them, or a combination of these may be used. Specific examples of the di- or multi-vinyl 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 their analogs, among which divinyl aromatic hydrocarbons are preferred,
In particular, isomers such as ortho, meta and para selected from divinylbenzene are more preferable. Three types of isomers
Good results have been obtained when commercialized divinylbenzene obtained by mixing and other compounds is used. The above di-
Or, as the multi-epoxide, for example, epoxidized polybutadiene solution, epoxidized vegetable oil, epoxide, and the like are suitable. Examples of the epoxidized vegetable oil include epoxidized soybean oil and epoxidized linseed oil. Examples of the above multiisocyanates are benzene-1,2,4
-Triisocyanate (bezene-1,2,4-triisocyanate),
Naphthalen-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. Aziridinylphosphine oxide or sulfide, specifically, tri (1-aziridinyl) phosphine oxide [tri (1-aziridinyl) phosphi
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. Representative examples of the above multialdehyde are 1,4,7-naphthalenetricarboxyaldehyde (1,4,7-naphthalenetricarboxyal
dehyde), 1,7,9-anthracenetricarboxyaldehyde, 1,1,5-pentanetricarboxaldehyde (1,1,5-pentanetricarboaldehyde)
xyaldehyde) and aliphatic or aromatic compounds containing multialdehyde. Typical examples of multiketones are 1,
4,9,10-anthracenetet (1,4,9,10-anthracenetet
rone), 2,3-diacetonylcyclohexanone (2,3-diacet
onylcyclohexanone), and the like. Examples of multianhydrides include pyromellitic anhydride (pyromelli
tic dianhydride), styrene-maleic anhydride copolymer
(styrene-maleic anhydride copolymers) and similar substances. The multiester is, for example, diethyl-adipate (diethyladipate), triethyl citrate (triethy
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 attaches to the α-type carbon atom of the active group, such as an ether bond, a carbonyl group, or a carbon-carbon double bond. In the method for producing the polymer according to the present invention, the polymerization temperature is generally -40 to 150 ° C, preferably 40 to 120 ° C, and the polymerization time varies depending on the polymerization conditions, and is usually within 48 hours, preferably 0.5 to 10 hours. It is. Impurities during polymerization,
For example, it is necessary to prevent contamination of water, acid, carbon dioxide, and the like, and the weight average molecular weight of the polymer is generally
5,000 to 5,000,000, especially 10,000 to 1,000,000 is more preferred.

In the present invention, a living polymer obtained by polymerizing the above-mentioned polymerization components under the above-mentioned conditions as described above is post-treated in the order of the following steps (1) to (3). 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 organic acid per 100 parts by weight of the living polymer.
(2) 100 parts by weight of living polymer and at least 1 part by weight of water; (3) 100 parts by weight of living polymer, (a) phenolic antioxidant and (b) The following general formula (I)

[0011]

Embedded image

(Wherein R ₁ and R ₃ are each —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. ) Is added in a total amount of 0.02 to 0.5 parts by weight of the antioxidant. Here, the organic acid in the first step (1) refers to an acidic organic compound, and is selected from compounds such as carboxylic acid, sulfonic acid, sulfinic acid, and phenol, and is preferably an organic compound having a carboxyl group. Examples include formic, acetic, pentanoic, octanoic, lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic, ricinoleic,
Examples include behenic acid and versatic acid, and versatic acid is particularly preferred. The method of adding the organic acid used in the present invention is not particularly limited. For convenience of operation, it is preferable to dissolve the organic acid in a solvent and then add a 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 at most 10 ppm, more preferably at most 1 ppm. The amount of the organic acid to be 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 is less than 0.01 part by weight, the hue of the polymer cannot be improved, and if the amount is more than 1 part by weight, the physical properties of the conjugated diene polymer or the next processing / application If more than 1 part by weight of an organic acid is added to a batch-type conjugated diene polymerization reactor, the organic acid will remain in the polymer and affect the polymerization reaction of the next batch. The organic acid can also be used as a terminator for the polymerization reaction of the living polymer (that is, a deactivation agent for the polymerization active site). However, in order to achieve such effects, the amount added must be accurately controlled, and an improper amount reduces the thermal stability of the polymer, deteriorates the hue, and further affects the quality of the polymer. I do.

In the production method of the present invention, the step of adding an organic acid to the step (1) of the post-treatment of the produced living polymer and then adding a large amount of water in the step (2) is completely carried out with a large amount of water. This is because there is an advantage that the reaction of a small amount of residual active terminal groups can be stopped, and unstable substances generated by the initiator reaction, such as lithium hydride and lithium chloride, dissolve in water during the reaction, and Because the unstable substance does not adversely affect the hue, thermal stability, transparency, etc. of the conjugated diene polymer. The amount of water used in the second step 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 in the polymerization reaction tank, in the outlet pipe of the reaction tank, or in the intermediate storage tank, and from the viewpoints of work convenience and quality stability. More preferably, it is added into the outlet line of the reaction tank. Although not particularly limited, pure water is preferably used for quality stability. In the production method of the present invention, the antioxidant added in the third step of the post-treatment can be classified into two types, a and b.

(A) is a phenolic antioxidant, and 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
-Tert-butyl-4-oxyphenyl) propionate, triglycol-bis- [3- (3-tert-butyl-5-methyl-4-oxyphenyl)] propionate, 1,3,5-tri- ( 4-tert-butyl-3-hydroxy-2,6-dimethylphenyl) isocyanic acid, 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 3,9-bis- { 2-[(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-
Dimethylethyl} -2,4,8,10-tetra-ethanedioil [5,
5] undecane, 4-hydroxymethyl-2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, butylated-hydroxy-phenylmethyl 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, among which octadecyl-3- (3,5-di-tert-butyl-4-oxyphenyl) propionate is more preferred. The phenolic antioxidant (a) used in the present invention does not contain the thiophenol-based antioxidant (b) represented by the following formula (I).

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

[0016]

Embedded image

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
15 or less alkyl, as a specific example, 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 preferred. Antioxidant used in the present invention
(a), (b) the total amount of the two, based on 100 parts by weight of the living polymer is 0.02 to 0.5 parts by weight, preferably 0.02 to 0.3 parts by weight, particularly preferably 0.02 to 0.21 parts by weight, among which so,
The amount of the antioxidant (a) used is 0.01 to 0.18 parts by weight, preferably 0.01 to 0.09 parts by weight. The amount of the antioxidant (b) used is 0.01 to 0.32 parts by weight, preferably 0.01 to 0.21 parts by weight, more preferably 0.01 to 0.12 parts by weight. Antioxidant (a)
And the total amount of antioxidant (b) exceeds 0.5 parts by weight,
If the amount of the antioxidant (b) exceeds 0.32 parts by weight, the initial hue of the polymer is adversely affected. On the other hand, when the total amount of the antioxidant (a) and the antioxidant (b) is less than 0.02 parts by weight, or when the amount of the antioxidant (b) used is 0.01 part by weight or less, the conjugated diene-based The hue, thermal stability, processing stability, etc. of the polymer also deteriorate. In addition, as the antioxidant, a phosphorus-based antioxidant, a thioether-based antioxidant, or a sterically hindered amine-based antioxidant may be used, and the amount used is in the range of 0.01 to 0.5 part by weight. The phosphorus-based antioxidant is a phosphite-based antioxidant or a phosphate-based antioxidant, and typical examples thereof include tris (nonylphenyl) phosphite, laurylphosphite, and cycloneopentyltetrahydronaphthylbis.
(Octadecylphosphite), 4,4'-butyl bis (3-
Methyl-6-tert-butylphenyl-bistridecanoyl phosphite), tris (2,4-tert-butylphenyl) phosphite, tetrakis (2,4-tert-butylphenyl)
4,4'-biphenylenediphosphonite, 9,10-dihydro
-9-oxa-10-phosphaphenanthrene-10-oxide and the like. Representative examples of thioether-based antioxidants include dioctadecanoyl thiodipropionate,
Dipalmityl thiodipropionate, pentaerythritol
-Le-tetrakis- (β-lauryl-thiopropionate),
Examples include bislauryl thioether, bistridecyl thioether, bistetradecyl thioether, and bisoctadecyl thioether. According to the production method of the present invention,
By adding a small amount of an antioxidant to the conjugated diene-based polymer, that is, 0.5 parts by weight or less in total of the antioxidants (a) and (b), sufficient thermal stability, good hue and processing for the copolymer are obtained. Sex can be given. On the other hand, post-processing steps (1), (2), (3)
Absence of any of the processing conditions, such as observing the order of the above and adding an organic acid in the step (1) and adding at least 1 part by weight of water in the step (2) is a good hue and color. Has a significant adverse effect on stability. In the post-treatment step (3) of the present invention, the additives may be directly charged into the reaction vessel, further stirred and mixed, or added into a pipe to form static mixing. 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 post-treatment steps (1), (2) and (3), as a method for devolatilizing the solvent in the polymer solution, for example, a known method, e.g., heating and evaporating the polymer solution to remove the solvent How to remove or water,
Alternatively, after adding and dispersing heated water, vapor devolatilization is performed by evaporating the solvent with steam, or a large amount of a precipitant such as methanol is added to the polymer, and then the polymer precipitate is deposited. Separation method, a vacuum evaporation method of the polymer solution, a method of directly squeezing the solvent with an extruder provided with a devolatilization port, and devolatilization.

[0018]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited to these examples. <Test method> 1. Polymer Hue and Thermal Stability Test The polymer is compression molded into a 4 inch × 4 inch × 1/8 inch sheet and the yellow index, ie, YI, is measured with a color difference meter. After heating the sheet in an oven at 200 ° C. for 30 minutes, a change in color tone is measured as thermal stability. In Table 1, ◎ Slightly yellow ○ Light yellow △ Dark yellow × Brown Processing stability test of polymer Place 60 g of polymer on a brabander measuring machine, 150 ° C x 60 rpm
Under the conditions of (1) and (2), a curve diagram of the torque (torque) and time is recorded to determine 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 washing 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 in the reactor. 5.5 g of butyllithium was added, reacted at 55 ° C. for 1 hour, and 1.5 g of silicon tetrachloride (SiCl ₄ ) was further added to obtain a star-type living polymer A. (Preparation of Living Polymer B) A linear-type living polymer was prepared in the same manner as in (Preparation of Living Polymer A), except that the amount of added n-butyllithium was 7.5 g and silicon tetrachloride was not used. Got B. (Preparation of Living Polymer C) Similarly, a 200-liter reactor was washed with nitrogen gas, and 3.2 Kg of styrene and 9.4 Kg of butadiene were mixed with 110 Kg of an n-hexane solvent in the reactor, followed by 11.4 g of tetrahydrofuran. Potassium butoxide (potassi
um butoxide) 6.4 g, pre-heated at a temperature of 70 ° C., further added 9.7 g of n-butyllithium and allowed to react for 1 hour, then linear type living polymer C (butadiene-styrene copolymer) I got [Examples 1 to 6] Living polymer A obtained in the above preparation example,
Post-treatments of B and C were performed in the following steps under the addition conditions shown in Table 1. That is, in step (1), an organic acid was added to the living polymer solution and mixed well. Step (2), water was added. In step (3), an antioxidant was added and mixed. The polymer was devolatilized in a steam stripping step to remove the solvent and then dried to obtain a conjugated diene polymer. The properties are shown in Table 1. [Comparative Examples 1 to 6] In the same manner as in Example 1, the types of additives in steps (1), (2) and (3) and the amounts of the additives were changed as shown in Table 1. Table 1 shows the physical property test results. As can be seen from the results of the above Examples shown in Table 1, an organic acid was added to the living polymer as a terminator, and water was also added as a terminator in the order of steps (1), (2), and (3). Further, by adding an appropriate amount of an antioxidant, a polymer having good hue, good thermal stability and excellent processing stability can be obtained. On the other hand, from the results of the comparative examples shown in Table 1, when the organic acid and water were not added in steps (1) and (2), respectively, when the amount of the antioxidant used was large, and when the amount of the antioxidant was large, it was limited in step (3). Hue, heat stability and processing stability when the amounts of antioxidants (a) and (b) used are not used in accordance with the prescribed procedures or when the steps (1), (2) and (3) are not performed in the specified order. It can be seen that a polymer having good properties cannot be obtained.

[0019]

[Table 1]

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

Claims (6)

[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. (1) a method for producing a conjugated diene polymer, comprising performing post-treatment in the order from the step to the step (3), and then devolatilizing the obtained polymer solution to recover the polymer; Organic acid 0.01-1 based on 100 parts by weight of living polymer
(2) 100 parts by weight of living polymer and at least 1 part of water
(3) per 100 parts by weight of the living polymer, (a) 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) Add a total of 0.02-0.5 parts by weight of the antioxidant to be used. 2. An antioxidant to be added to the third step of the post-treatment is (a) 0.01 to 0.18 parts by weight of a phenolic antioxidant and (b) 0.01 to 0.32 parts by weight of the formula (I). 2. The method for producing a conjugated diene polymer according to claim 1, comprising an antioxidant represented by the formula: 3. An antioxidant to be added to the third step of the post-treatment is (a) 0.01 to 0.09 parts by weight of a phenolic antioxidant and (b) 0.01 to 0.21 parts by weight of the formula (I). 2. The method for producing a conjugated diene polymer according to claim 1, comprising an antioxidant represented by the formula: 4. The water (2-50) as a (2) step of the post-treatment.
2. The method for producing a conjugated diene polymer according to claim 1, wherein parts by weight are added. 5. The method according to claim 1, wherein in the step (1) of the post-treatment, the organic acid is versatic acid.
3. The method for producing a conjugated diene polymer according to item 1. 6. In the third step of the post-processing, a formula
2. The method for producing a conjugated diene polymer according to claim 1, wherein the antioxidant represented by (I) is 4,6-bis- (octylthiomethyl) -o-methylphenol.