JPH0456041B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a polymer having excellent color tone, transparency, resistance to devitrification, and resistance to heat discoloration. [Prior Art] A block copolymer composed of a conjugated diene and a vinyl aromatic hydrocarbon is transparent when the vinyl aromatic hydrocarbon content is relatively small, and can be used as a vulcanized natural rubber or vulcanized natural rubber without vulcanization. It has the same elasticity as synthetic rubber at room temperature and the same processability as thermoplastic resin at high temperatures, so it is widely used in the fields of footwear, plastic modification, asphalt, adhesives, etc. In addition, when the vinyl aromatic hydrocarbon content is relatively high, a thermoplastic resin that is transparent and has excellent impact resistance can be obtained, so its usage has increased in recent years, mainly in the food packaging container field, and its applications have also expanded. It is becoming more diverse. However, such block copolymers have the disadvantage that the color tone is poor and the molded products exhibit a yellowish tinge. Therefore, several methods have been attempted to improve this drawback. For example, in Japanese Patent Publication No. 54-2679, in the hydrocarbon solvent of the activated block copolymer,
A method of directly removing the solvent by adding water/carbon dioxide/phenolic antioxidant and treating at a temperature in the range of 150 to 200°C is described.
No. 7459 describes a method in which a hydrocarbon solution of a block copolymer is heated or mixed with heated water and brought into contact with an aqueous solution of an organic acid compound before stripping the solvent. Also, JP-A-58-
Japanese Patent No. 168612 describes a method for recovering the polymer by adding boric acid to the polymer and then adding a stabilizer. [Problems to be Solved by the Invention] However, although the color tone is improved by these methods, it is still insufficient, and there are problems in that the transparency, resistance to devitrification, and resistance to heat discoloration are inferior. Under these circumstances, the inventors of the present invention have conducted studies on methods for obtaining polymers with excellent color tone, transparency, devitrification resistance, and heat discoloration resistance. It has been discovered that the object can be achieved by adding a terminator and removing the solvent, and then contacting it with a specific amount of carbon dioxide in the presence of a very small amount of water or in the absence of water, and the present invention I have come to complete it. [Means for solving the problem] That is, the present invention provides a polymer obtained by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon in a hydrocarbon solvent using an organolithium compound as an initiator, or a polymer obtained by polymerizing the water of the polymer. Add a stabilizer or a stabilizer and a terminator to the solution of additives, b) reduce the amount of residual solvent in the polymer to 30 parts by weight or less per 100 parts by weight of the polymer, and then add 100 parts by weight of the polymer. c. A method for producing a polymer, which comprises contacting 100 parts by weight of carbon dioxide with 0.01 parts by weight or more of carbon dioxide in the presence of 0.5 parts by weight or less of water or in the absence of water. Regarding. The present invention will be explained in detail below. In the method of the present invention, a conjugated diene and/or vinyl aromatic hydrocarbon is polymerized in a hydrocarbon solvent using an organolithium compound as an initiator to produce a polymer solution. Polymers of conjugated dienes or vinyl aromatic hydrocarbons can be produced by any known method, including anionic polymerization of conjugated dienes or vinyl aromatic hydrocarbons with an organolithium compound in an inert hydrocarbon solvent. It can be manufactured by. When a conjugated diene and a vinyl aromatic hydrocarbon are used as monomers, the composition ratio of the conjugated diene and the vinyl aromatic hydrocarbon in the resulting polymer is not particularly limited, but is generally 99.9:0.1 to 0.1:99.9, preferably
It can be changed within the range of 98:2 to 5:95. The polymer consisting of a conjugated diene and a vinyl aromatic hydrocarbon may be a random polymer or a block copolymer, and is prepared by any known method in an inert hydrocarbon solvent. It can be produced by anionic polymerization of a compound. For example, random copolymers are covered by U.S. Patent 3094514.
It can be prepared by feeding a mixture of a conjugated diene and a vinyl aromatic hydrocarbon to a polymerization vessel at a slower than normal polymerization rate, as described in that application. Alternatively, as described in U.S. Pat. No. 3,451,988, a random copolymer is produced by copolymerizing a mixture of a conjugated diene and a vinyl aromatic hydrocarbon in the presence of a polar compound or a randomizing agent, which will be described later. be able to. On the other hand, as a method for producing block copolymers,
For example, Japanese Patent Publication No. 19286-1986, Publication No. 17979-1979, Publication No. 32415-1982, Publication No. 36957-1987, Publication No. 2423-1983, Publication No. 4106-1986, Publication No. 48-4106, Examples include methods described in Publication No. 56-28925, Japanese Patent Publication No. 49567-1980, and the like. By these methods, block copolymers can _be produced using the following general _{formulas :} B is a polymer block mainly composed of conjugated diene. The boundary between A block and B block does not necessarily need to be clearly distinguished. Also, n is an integer of 1 or more. ) or the general formula, [(B-A) _o −] _n+1 X, [(A-B) _o −] _n+1 X [(B-A) _o B-] _n+1 X, [(A-B) _o A-] _n+1
X (In the above formula, A and B are the same as above,
X is, for example, silicon tetrachloride, tin tetrachloride, polyepoxide such as epoxidized soybean oil, polyhalogenated hydrocarbon, carboxylic acid ester, polybasic acid ester, polybasic acid anhydride, polyfunctional isocyanate,
It shows the residue of a coupling agent such as a polyfunctional aldehyde, a polyfunctional ketone, a polyvinyl aromatic compound, or the residue of an initiator such as a polyfunctional organolithium compound. m
and n is an integer of 1 or more. ) It is obtained as a block copolymer represented by:
In the above formula, the polymer block mainly composed of vinyl aromatic hydrocarbons refers to
It refers to a copolymer block of vinyl aromatic hydrocarbon and conjugated diene containing 50% by weight or more and/or a vinyl aromatic hydrocarbon homopolymer block containing 50% by weight or more. A copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon containing an amount exceeding % by weight and/or
Or a conjugated diene homopolymer block. The vinyl aromatic hydrocarbons in the copolymer block may be uniformly distributed or tapered. Further, the copolymer portion may include a plurality of portions in which vinyl aromatic hydrocarbons are uniformly distributed and/or a plurality of portions in which vinyl aromatic hydrocarbons are distributed in a tapered manner. The block copolymer thus obtained exhibits properties as a thermoplastic elastomer when the vinyl aromatic hydrocarbon content is 60% by weight or less, preferably 55% by weight or less, and the vinyl aromatic hydrocarbon When the content exceeds 60% by weight, preferably 65% by weight or more, it exhibits properties as a thermoplastic resin. Vinyl aromatic hydrocarbons used in the method of the present invention include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3
-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, etc., and particularly common ones include styrene, p-methylstyrene, and α-methylstyrene. These may be used not only alone, but also as a mixture of two or more. The conjugated diene used in the present invention is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,
3-butadiene, 1,3-pentadiene, 1,3
-hexadiene, etc., and particularly common ones include 1,3-butadiene and isoprene. These may be used not only alone, but also as a mixture of two or more. Hydrocarbon solvents include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, isooctane, cyclopentane,
Alicyclic hydrocarbons such as methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene can be used. These may be used not only alone, but also as a mixture of two or more. Organolithium compounds include organic monolithium compounds, organic dilithium compounds, organic polylithium compounds, etc. in which one or more lithium atoms are bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium, and n-butyllithium. , sec-butyllithium, tert-butyllithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium, and the like. These may be used not only alone, but also as a mixture of two or more. In the present invention, polar compounds and Randomizing agents can be used. Examples of polar compounds and randomizing agents include ethers, amines, thioethers, phosphoramides, alkylbenzene sulfonates, potassium or sodium alkoxides, and the like. Examples of suitable ethers are dimethyl ether, diethyl ether, diphenyl ether and tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether. As the amines, in addition to tertiary amines such as trimethylamine, triethylamine, and tetramethylethylenediamine, cyclic tertiary amines can also be used. Phosphines and phosphoramides include triphenylphosphine and hexamethylphosphoramide. Randomizing agents include potassium or sodium alkylbenzene sulfonate, potassium or sodium butoxide, and the like. The polymerization temperature for producing the polymer in the method of the present invention is generally -10°C to 150°C, preferably
The temperature is between 40℃ and 120℃. The time required for polymerization varies depending on the conditions, but is usually within 48 hours.
Particularly preferred is 1 to 10 hours. Further, it is desirable to replace the atmosphere of the polymerization system with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is within a pressure range sufficient to maintain the monomer and solvent in a liquid phase within the above polymerization temperature range. Furthermore, care must be taken to avoid contamination of the polymerization system with impurities that would inactivate the catalyst and living polymer, such as water, oxygen, carbon dioxide, and the like. The weight average molecular weight of the polymer thus obtained is generally 5,000 to 5,000,000, preferably 10,000 to 5,000,000.
1000000. The amount of hydrocarbon in the polymer solution is generally 50 parts by weight to 100 parts by weight of the polymer.
2000 parts by weight. Depending on the nature of the polymer, the polymer may be insoluble in the hydrocarbon solvent and may be obtained in a suspended state; however, in the present invention, these will also be referred to as a polymer solution. Further, in the present invention, a polymer solution obtained by partially or selectively hydrogenating the polymer obtained above by a hydrogenation reaction (hydrogenation reaction) can be used. The hydrogenation rate can be selected arbitrarily, and when improving heat deterioration resistance etc. while maintaining the properties of the unhydrogenated polymer, the aliphatic double bond based on the conjugated diene is 3% or more and less than 80%. , preferably 5% or more and less than 75% hydrogenation, and in order to improve heat deterioration resistance and weather resistance, it is recommended to hydrogenate 80% or more, preferably 90% or more. The hydrogenation rate can be measured using a nuclear magnetic resonance apparatus or the like. Catalysts used in hydrogenation reactions include (1) supported heterogeneous catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on supports such as carbon, silica, alumina, and diatomaceous earth;
(2) So-called Ziegler type catalysts using organic acid salts such as Ni, Co, Fe, Cr, etc. or acetylacetone salts and reducing agents such as organic Al, or so-called organic complex catalysts such as organometallic compounds such as Ru, Rh, etc. Homogeneous catalysts are known. As a specific method, Tokukosho
42-8704, Japanese Patent Publication No. 43-6636, or JP-A-59-133203, JP-A-60-220147 in the presence of a hydrogenation catalyst in an inert solvent. can be hydrogenated to obtain a hydrogenated polymer solution. A stabilizer or a stabilizer and a terminator are added to the polymer solution obtained above (step (a)). Adding these at this stage is effective in preventing oxidative deterioration and thermal deterioration of the polymer when the solvent is removed in the next step. These may be added to the polymer solution as they are, or may be added after being dissolved in a hydrocarbon solvent. As the stabilizer, any of the known stabilizers that have been used conventionally may be used, and various known antioxidants such as phenol type, organic phosphate type, organic phosphite type, amine type, and sulfur type are used. Stabilizers are generally polymeric
It is used in a range of 0.001 to 10 parts by weight per 100 parts by weight. As the terminator, known terminators capable of deactivating living polymers produced with organolithium compounds, such as compounds having active hydrogen, can be used, but suitable ones include water, alcohol (methanol, ethanol, etc.). , propanol, etc.), polyhydric alcohols (ethylene glycol, propylene glycol, glycerin, etc.), primary amines, secondary amines, and mixtures thereof.
These are generally 0.01 parts by weight per 100 parts by weight of the polymer.
It is used in a range of 10 parts by weight, preferably 0.05 to 5 parts by weight. The terminator may be added before adding the stabilizer, or may be added at the same time as the stabilizer.
Note that it is not preferable to use a large amount of water as a quenching agent because it deteriorates transparency and devitrification resistance. Therefore, if water is used as a quenching agent, the polymer 100
It is not more than 5 parts by weight, preferably not more than 3 parts by weight. In particular, less than equimolar amount, preferably 1/2 of the organolithium compound used in polymerization.
It is recommended that the amount be less than mol. Next, remove the solvent from the polymer solution (step
(b). At this time, it is recommended to remove the solvent until the amount of the remaining solvent is 30 parts by weight or less, preferably 10 parts by weight or less, and more preferably 5 parts by weight or less based on 100 parts by weight of the polymer. Preferred for obtaining polymers. The method for removing the solvent from the polymer solution may be any known method, such as heating the solution to evaporate the solvent, dispersing the solution in water or hot water, and blowing water vapor to evaporate the solvent ( (steam stripping method), a method in which a large amount of a precipitant such as methanol is added to precipitate the polymer and separate it from the solvent, a method in which the solution is vacuum dried, a method in which a part of the solvent is evaporated in a flash tower, etc. Furthermore, a method of removing the solvent using a vented extruder can be adopted. Next, the amount of residual solvent in the polymer is reduced to 30 parts by weight or less based on 100 parts by weight of the polymer, and then 0.5 parts by weight or less, preferably 0.3 parts by weight or less, more preferably 0.3 parts by weight or less based on 100 parts by weight of the polymer. The amount of water is preferably 0.1 parts by weight or less, particularly preferably less than equimolar to the organolithium compound used for polymerization, and furthermore, 1/2 mole or less of water is brought into contact with carbon dioxide gas in the presence of water or in the absence of water. (Step (c)). If the amount of water exceeds 0.5 part by weight, it is not preferable because transparency and resistance to devitrification deteriorate. The amount of carbon dioxide used is 0.01 parts by weight or more, preferably 0.03 to 10 parts by weight, based on 100 parts by weight of the polymer.
More preferably, it is 0.1 to 3 parts by weight. If the amount of carbon dioxide gas is less than 0.01 parts by weight, the color tone, resistance to heat discoloration, and colorability with pigments will be poor, which is not preferable. The carbon dioxide gas used may be solid as dry ice or gaseous. There are no particular restrictions on the method of contacting the polymer obtained by removing the solvent from the polymer solution with carbon dioxide gas in the substantial absence of water, but preferred methods include contacting the polymer obtained by removing the solvent from the polymer solution with carbon dioxide gas, or Examples include a method of bringing the mixture into contact with the polymer in a carbon dioxide-containing gas (air, nitrogen, helium, argon, etc.), and a method of supplying carbon dioxide and the polymer into a conventionally known kneader for kneading. As the kneading machine, an open roll, an intensive mixer, an internal mixer, a co-kneader, a continuous kneader with a twin-screw rotor, a single-screw, twin-screw or multi-screw extruder, etc. are used. The contact time between carbon dioxide gas and the polymer is 0.1 seconds to about 1 month, preferably 1 month.
Seconds to about one week is recommended. In addition, in the method of the present invention, if it is desired to further remove the solvent remaining in the polymer after contacting with carbon dioxide gas, it can be removed by adopting any of the solvent removal methods described above. good. The most preferred embodiment of the method of the present invention is to reduce the amount of residual solvent in the polymer by heating and evaporating the solvent from a polymer solution to which a stabilizer or a stabilizer and a terminator have been added, or by steam stripping.
5% by weight or less, preferably 1% by weight based on 100 parts by weight
After reducing the amount to % by weight or less, carbon dioxide gas is added and kneaded using an extruder (including a vented extruder), or a polymer solution containing a stabilizer or a stabilizer and a terminator is used to remove the solvent in a flash tower. In a method of recovering a polymer by partially evaporating the remaining solvent and further removing the residual solvent using a vented extruder, the amount of residual solvent in the polymer is 5 parts by weight or less based on 100 parts by weight of the polymer,
Preferably, a method of adding carbon dioxide gas in the step of reducing the amount to 1 part by weight or less, a heating evaporation method, a steam stripping method, a vent type extruder method for removing the solvent from a polymer solution to which a stabilizer or a stabilizer and a terminator have been added. After reducing the amount of residual solvent in the polymer to 5 parts by weight or less, preferably 1 part by weight or less based on 100 parts by weight of the polymer, the polymer is left to stand in nitrogen gas or air containing a predetermined amount of carbon dioxide. I can give you a method. Various additives can be added to the polymer obtained by the method of the present invention depending on the purpose.
For example, softeners such as oil, plasticizers, antistatic agents, lubricants, ultraviolet absorbers, flame retardants, pigments, inorganic fillers, organic and inorganic fibers, reinforcing agents such as carbon black, and other thermoplastic resins. Can be used as an additive. The polymer obtained by the method of the present invention does not have problems such as color change due to the addition of additives, such as yellowing due to the addition of ultraviolet absorbers, abnormal color tone due to the addition of pigments, etc., and therefore is compatible with various additives. A wide range of combinations are possible. EXAMPLES The present invention will be explained in more detail with reference to Examples below. The block copolymers used in the examples were produced as follows. The weight ratio of polymer to solvent in each of the obtained polymer solutions was 1:4. [Block copolymer (A)] In a nitrogen gas atmosphere, 0.11 parts by weight of n-butyllithium was added to an n-hexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene, and the mixture was heated at 70°C for 2 hours. After polymerization for a period of time, an n-
A hexane solution was added and polymerization was carried out at 70°C for 2 hours. The obtained polymer had a styrene content of 40% by weight.
It was a block copolymer with an ABA structure. [Block copolymer (B)] In a nitrogen gas atmosphere, 0.11 parts by weight of n-butyllithium was added to a cyclohexane solution containing 15 parts by weight of styrene, and after polymerization at 70°C for 1 hour,
A cyclohensane solution containing 70 parts by weight of 1,3-butadiene was added and polymerized at 70°C for 2 hours. Thereafter, a cyclohexane solution containing 15 parts by weight of styrene was further added, and polymerization was carried out at 70°C for 1 hour. The obtained polymer was a block copolymer having an ABA structure with a styrene content of 30% by weight. [Block copolymer (C)] In a nitrogen gas atmosphere, 0.08 parts by weight of n-butyllithium was added to a cyclohexane solution containing 30 parts by weight of styrene and 0.3 parts by weight of tetrahydrofuran, and after polymerization at 70°C for 1 hour, further A cyclohexane solution containing 20 parts by weight of 1,3-butadiene and 50 parts by weight of styrene was added and polymerized at 70°C for 2 hours.
The obtained polymer had a styrene content of 80% by weight.
It was a block copolymer with a B-A structure. [Block copolymer (D)] In a nitrogen gas atmosphere, 0.07 parts by weight of n-butyllithium was added to an n-hexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene, and the mixture was heated at 70°C for 2 hours. After polymerization for an hour, an n-hexane solution containing 15 parts by weight of 1,3-butadiene and 50 parts by weight of styrene and 0.02 part by weight of n-butyllithium were further added, followed by polymerization at 70 DEG C. for 2 hours. The obtained polymer is a mixture of a B-A-B-A structure block copolymer and a B-A structure block copolymer with a styrene content of 70% by weight, and the obtained polymer solution is It was in a suspension state. [Block copolymer (E)] In a nitrogen gas atmosphere, 0.15 parts by weight of n-butyllithium was added to a cyclohexane solution containing 75 parts by weight of styrene, and after polymerization at 70°C for 1 hour,
A cyclohensane solution containing 25 parts by weight of 1,3-butadiene was added and polymerized at 70°C for 2 hours. Thereafter, 5 parts by weight of epoxidized soybean oil was added to obtain a radial structure block copolymer having a styrene content of 75% by weight. [Block copolymer (F)] In a nitrogen gas atmosphere, 0.08 parts by weight of n-butyllithium was added to an n-hexane solution containing 80 parts by weight of 1,3-butadiene and 20 parts by weight of styrene, and the mixture was heated at 70°C for 2 hours. Polymerized for hours. The obtained polymer was a block copolymer of BA structure with a styrene content of 20% by weight. Examples 1 to 3 and Comparative Examples 1 to 4 4-methyl-2,6-di-tert-butylphenol and trisnonylphenyl phosphorite were added as stabilizers to the solution of the block copolymer (C) produced above. After adding 0.5 parts by weight of each to 100 parts by weight of the polymer, the solvent was removed by heating until the amount of solvent remaining in the polymer became 1 part by weight or less. Thereafter, carbon dioxide gas was added according to the addition treatment shown in Table 1, and the mixture was extruded into pellets using a 30 mmφ extruder. The obtained pellets were press-molded at 180℃ to create a sheet with a thickness of 2 mm, and the color tone, transparency, resistance to devitrification, resistance to heat discoloration, and colorability with pigments were measured. The results are shown in Table 1. Indicated. On the other hand, in Comparative Example 2, 1 part by weight of carbon dioxide gas and 1 part by weight of water were added to 100 parts by weight of the block copolymer to form pellets. In addition, in Comparative Example 3,
Carbon dioxide gas in an amount 3 times the molar equivalent of lithium in n-butyllithium used for polymerization of the block copolymer (C) and 10 parts by weight per 100 parts by weight of the block copolymer
After adding parts by weight of water to the polymer solution, 0.5 parts by weight of 4-methyl-2,6-di-tert-butylphenol was added to 100 parts by weight of the polymer, and the solvent was removed by heating. Furthermore, in Comparative Example 4, an aqueous solution of 0.005 parts by weight of tartaric acid dissolved in 20 parts by weight of water and the stabilizer-containing polymer solution containing 100 parts by weight of block copolymer (C) were shaken for about 10 minutes, and then The polymer solution layer separated by standing was dropped little by little onto heated water at 80 to 85°C to evaporate the solvent.

【table】

[Table] Examples 4 to 7 and Comparative Examples 5 to 8 After adding 0.3 parts by weight of a terminator to each living polymer solution of the block copolymer shown in Table 2, based on 100 parts by weight of the block copolymer, Octadecyl-3-(3',5'-di-tert-
After adding 0.5 parts by weight of each of butyl-4-hydroxyphenyl) propionate and trisnonyl phenyl phosphite to 100 parts by weight of the polymer, the solvent was added until the amount of residual solvent in the polymer became 1 part by weight or less. was removed by heating. Then the polymer
Per 100 parts by weight, 1 part by weight of carbon dioxide gas and the polymer were extruded using a 30 mmφ extruder to form pellets. still,
In the comparative example, extrusion was performed without adding carbon dioxide,
Made into pellets.

[Table] Examples 8 and 9 and Comparative Examples 9 and 10 4-Methyl-2,6-di-tert-butylphenol and trisnonylphenyl were added as stabilizers to the solutions of the block copolymers shown in Table 3. After adding 0.5 parts by weight of each phosphite to 100 parts by weight of the polymer, the solvent was removed by heating until the amount of residual solvent in the polymer became 1 part by weight or less. Thereafter, it was extruded into pellets or crumbs using a 30 mmφ extruder. Thereafter, the polymer was allowed to stand for one week at room temperature in sealed air containing 0.1 part by weight of carbon dioxide per 100 parts by weight of the polymer. On the other hand, in a comparative example, 1
I let it sit for a week.

【table】

〔effect〕

The polymer obtained by the method of the present invention is transparent and has excellent color tone, heat discoloration resistance, and coloring property by adding pigments, so it can be used to make sheets, films, injection molded products of various shapes, and blow molded products. It can be used as a wide variety of molded products, such as air-formed products, vacuum-formed products, etc. In particular, the polymer obtained by the method of the present invention is
Because of its excellent devitrification resistance, it can be used effectively in humid environments or in areas where it comes into contact with water, such as food containers, food packaging materials, toys, medical supplies, etc. Furthermore, the method of the present invention can be used to produce block copolymers of conjugated dienes and vinyl aromatic hydrocarbons, as well as conjugated diene polymers, vinyl aromatic hydrocarbon polymers, and random copolymers of conjugated dienes and vinyl aromatic hydrocarbons. It can also be used for merging.

Claims (1)

[Scope of Claims] 1. To a solution of a polymer obtained by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon using an organolithium compound as an initiator in a hydrocarbon solvent, or a hydrogenated product of the polymer, a. Add a stabilizer or a stabilizer and a terminator, b. After reducing the amount of residual solvent in the polymer to 30 parts by weight or less per 100 parts by weight of the polymer, add 0.5 parts by weight to 100 parts by weight of the polymer. A method for producing a polymer, which comprises contacting 100 parts by weight of c. with 0.01 parts by weight or more of carbon dioxide gas in the presence or absence of water as described below.