JP2013231145A - Method of purifying polymer solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of purifying a polymer solution, capable of obtaining a purified polymer solution by removing these metal residues efficiently from the polymer solution that contains at least lithium and/or titanium.SOLUTION: A method of purifying a polymer solution includes: a step 1 of preparing the polymer solution that contains at least lithium and/or titanium; and a step 2 of adding an inorganic flocculant to the polymer solution and then mixing them with each other.

Description

  The present invention relates to a method for purifying a polymer solution.

  In recent years, thermoplastic elastomers, which are soft materials having rubber elasticity, do not require a vulcanization step, and can be molded and recycled in the same manner as thermoplastic resins, are widely used in a wide range of fields.

  For example, a polymer of a conjugated diene monomer such as 1,3-butadiene or isoprene, or a vinyl aromatic monomer such as styrene copolymerizable with the conjugated diene monomer and the conjugated diene monomer. These copolymers are very important as impact-resistant transparent resins or modifiers for polyolefins and polystyrene resins.

  Moreover, the hydrogenated polymer obtained by adding hydrogen to the olefinic double bond portion contained in the conjugated diene polymer has a feature of excellent weather resistance. Taking advantage of this feature, hydrogenated polymers are used in automobile parts, home appliance parts, wire coverings, medical parts, sundries, footwear and the like.

  Generally, the conjugated diene polymer is produced by living anionic polymerization using an alkyl lithium as an initiator. Further, in the case of obtaining a hydrogenated polymer, a hydrogenation reaction (hereinafter also referred to as “hydrogenation reaction”) is performed on the olefinic double bond portion after polymerization by using a Group VIII or Group IV metal as a catalyst. I do.

  Various methods for hydrogenating a polymer having an olefinic double bond have been reported. For example, suitable compounds such as compounds of Group VIII of the periodic table, particularly nickel or cobalt compounds and alkylaluminum compounds are suitable. A hydrogenation method using a catalyst combined with a reducing agent is known. In addition, a titanium compound which is a group IV metal of the periodic table, for example, a bis (cyclopentadienyl) titanium compound and a catalyst in which an appropriate reducing agent such as an alkylaluminum compound is combined is used. Methods for hydrogenating unsaturated double bonds of polymers are known.

  As described above, thermoplastic elastomers, particularly conjugated diene polymers such as those described above, and hydrogenated polymers thereof include metal residues (hereinafter referred to as “catalyst residues”) derived from initiators and hydrogenation catalysts. Will be included). The metal residue in the polymer solution must be removed efficiently in the manufacturing process because it leads to various quality degradations such as product roughness, surface roughness, coloring, and turbidity.

  Therefore, several proposals have been made as methods for removing metal residues remaining in the polymer solution. For example, Patent Document 1 discloses a method of removing a lithium residue in a polymer solution by vigorously mixing the polymer solution and water using a rotary disperser having a meshing structure.

  Patent Document 2 discloses a method for removing residues of Group VIII metals in the periodic table including nickel using an oxidizing agent and dicarboxylic acid. Furthermore, Patent Document 3 discloses a method of adsorbing to silicate. In addition to the above, removal of lithium and group VIII metals of the periodic table has been disclosed in a number of prior literatures.

  On the other hand, there has been almost no report on a method for removing a titanium residue. For example, Patent Document 4 discloses removal of a titanium residue using an inorganic acid, an alcohol, and water. To the extent that Patent Document 5 discloses removal of a titanium residue using an organic acid, an alcohol, and water.

Japanese Patent Laid-Open No. 6-136034 US Pat. No. 4,595,749 US Pat. No. 5,104,972 JP 2002-167406 A JP 2009-91574 A

  Metal residues that cause product quality deterioration need to be efficiently removed from the polymer solution. However, as described above, in the prior art, there have been few reports on removal methods that have a high effect on lithium and titanium among a plurality of metal residues. Further, in the methods described in Patent Documents 4 and 5, it is necessary to use a large amount of alcohol and water at the time of metal removal, and waste liquid treatment becomes a big problem in industrial production.

  The present invention has been made in view of the above-described problems of the prior art, and is a method for efficiently removing these metal residues from a polymer solution containing at least lithium and / or titanium to obtain a purified polymer solution. It is an object of the present invention to provide a method for purifying a combined solution.

As a result of intensive studies to solve the above-mentioned problems, the present inventors treated a polymer solution containing at least lithium and / or titanium with an inorganic flocculant, so that lithium contained in the polymer solution. The present inventors have found that residues and titanium residues can be efficiently removed in a short time.
That is, the present invention is as follows.

[1]
Preparing a polymer solution containing at least lithium and / or titanium; and
And a step 2 of adding and mixing an inorganic flocculant to the polymer solution.
[2]
The method for purifying a polymer solution according to the above [1], wherein the polymer in the polymer solution is a conjugated diene polymer obtained by living anion polymerization.
[3]
The method for purifying a polymer solution according to [1] or [2], wherein the polymer solution further contains aluminum.
[4]
The method for purifying a polymer solution according to any one of [1] to [3], wherein in the step 2, the inorganic flocculant is mixed using an apparatus having a stirring strength P / V value of 100 or more.
[5]
In any one of the above [1] to [4], in the step 2, the inorganic flocculant is mixed using a rotary disperser having a meshing structure with a stirring strength P / V value of 30,000 or more. The purification method of the polymer solution as described.
[6]
The method for purifying a polymer solution according to any one of [1] to [5], wherein in step 2, an organic polymer flocculant is further added and mixed.
[7]
The method for purifying a polymer solution according to [6], wherein in the step 2, the organic polymer flocculant is mixed using an apparatus having a stirring strength P / V value of 100 or more.
[8]
In the step 2, the organic polymer flocculant is mixed using a rotary disperser having a meshing structure with a stirring strength P / V value of 30,000 or more. A method for purifying the polymer solution.

  According to the present invention, a lithium residue and / or a titanium residue contained in a polymer solution can be efficiently removed in a short time by treating with an inorganic flocculant, thereby a purified polymer solution with less metal residue. Can be obtained.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist.

[Polymer solution purification method]
The method for purifying the polymer solution of the present embodiment includes a step 1 of preparing a polymer solution containing at least lithium and / or titanium,
Step 2 of adding and mixing an inorganic flocculant to the polymer solution.
Hereinafter, each process is explained in full detail.

[Step 1]
In the method for purifying a polymer solution of the present embodiment, step 1 is a step of preparing a polymer solution containing at least lithium and / or titanium.

(Polymer solution containing lithium and / or titanium)
The polymer solution purified in the present embodiment contains at least lithium or titanium, or both, and may further contain aluminum. The method for preparing the polymer solution is not particularly limited. For example, a hydrogenation reaction is performed on a conjugated diene polymer polymerized by a lithium polymerization catalyst under a catalyst composed of a titanium compound and various reducing agents. The method of preparing the prepared conjugated diene type copolymer solution is mentioned. In this embodiment, a conjugated diene polymer solution before the hydrogenation reaction can also be prepared as a polymer solution to be purified.

(Polymer)
The conjugated diene polymer is not particularly limited as long as it is generally used in the art, but a conjugated diene polymer obtained by living anion polymerization is preferable. In this embodiment, the catalyst residue used in the living anion polymerization can also be removed. Specifically, a conjugated diene homopolymer having a number average molecular weight of 500 to 1,000,000, or a random, tapered or block copolymer of a conjugated diene monomer and a vinyl aromatic monomer is used. be able to. Moreover, the polymer which hydrogenated with respect to the unsaturated double bond of these conjugated diene units can also be used.

  The number average molecular weight can be determined in terms of polystyrene using gel permeation chromatography (GPC).

  The conjugated diene monomer that can be used is not particularly limited, and specifically, 1,3-butadiene, isoprene, piperylene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl. Conjugated diene compounds containing 4 to 12 carbon atoms such as -1,3-octadiene can be used, and among these, it is preferable to use 1,3-butadiene and isoprene. The vinyl aromatic monomer copolymerizable with the conjugated diene monomer is not particularly limited. Specifically, styrene, α-methylstyrene, styrene substituted with an alkoxy group, 2-vinylpyridine, Vinyl allyl compounds such as 4-vinylpyridine, vinylnaphthalene and vinylnaphthalene substituted with an alkyl group can be used, and among these, styrene and α-methylstyrene are preferably used.

  At this time, when a copolymer is produced by mixing a conjugated diene monomer and a vinyl aromatic monomer, there is no particular limitation, but a mixing ratio of 5:95 to 95: 5 can be used. . When the amount of the conjugated diene used is 5% by mass or more, the impact resistance is good, and it can be used for various applications. Moreover, if it is 95 mass ratio or less, product workability will become favorable. Therefore, it is preferable to maintain the said range.

  Such a conjugated diene polymer can be produced by a polymerization method generally used in this field. For example, in this embodiment, anionic polymerization using an organolithium compound as an initiator can be performed. The organolithium compound is not particularly limited, and specifically, n-butyllithium, s-butyllithium, or the like can be used. The amount of such an initiator used is generally used in this field, and can be freely adjusted according to the molecular weight of the target polymer.

(Hydrogenation reaction)
Thereafter, a hydrogenated conjugated diene polymer can be produced by performing a hydrogenation reaction on the obtained polymer solution.

  The titanium compound used in the hydrogenation reaction is not particularly limited as long as it is generally used in the art, and specific examples include a cyclopentadienyl titanium compound. Enyltitanium halides, cyclopentadienyl (alkoxy) titanium dihalides, bis (cyclopentadienyl) titanium dihalides, bis (cyclopentadienyl) titanium dialkylates, bis (cyclopentadienyl) titanium diallylates and bis (Cyclopentadienyl) titanium dialkoxy compounds can be used alone or in combination.

  The titanium compound is preferably used in an amount of 0.01 to 20 mmol per 100 g of the conjugated diene polymer, and more preferably 0.05 to 5 mmol per 100 g of the polymer. If the usage-amount of the titanium compound used as a catalyst is 0.01 mmol or more, a hydrogenation reaction will advance efficiently and it will be excellent in productivity. Moreover, if it is 20 mmol or less, it will become sufficient catalyst addition amount and it will be economical, and also it will also suppress using excess chemical substance for catalyst removal after reaction. Therefore, it is preferable to maintain the said range.

  The reducing agent that can be used together with the titanium compound is not particularly limited as long as it is a reducing agent that is generally used in the field, and specifically, an alkylaluminum compound, an alkylmagnesium compound, an organolithium compound, A metal hydride etc. are mentioned, It can use even if it combines independently or multiple types.

  The hydrogenation reaction using the titanium-based catalyst is not particularly limited. Specifically, International Patent Application No. 00/08069, US Pat. Nos. 4,501,857, 4,673,714, 4,980,421, 5,753,778, 5,910,566, 6,020,439 and the like.

  The hydrogenation reaction can be performed in an inert solvent. Here, the inert solvent means a solvent that does not react with any reactant in the polymerization reaction or the hydrogenation reaction. Such an inert solvent is not particularly limited, but specifically, aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane; cyclopentane, cyclohexane, cycloheptane and the like. And alicyclic hydrocarbons; and ethers such as diethyl ether and tetrahydrofuran, which can be used alone or in combination.

  The polymer concentration in the polymer solution in Step 1 is not particularly limited, but is preferably 5 to 50% by mass, and more preferably 10 to 25% by mass. It is preferable for the polymer concentration to be in the above-mentioned range since it can be adjusted to a polymer solution viscosity that is easy to handle and the productivity is improved.

On the other hand, in the hydrogenation reaction, the polymer solution is maintained at a constant temperature in an inert gas atmosphere such as hydrogen, helium, argon, or nitrogen, and then a hydrogenation catalyst is added in a stirred or unstirred state, It is preferable to carry out by injecting at a constant pressure. Furthermore, the temperature of the hydrogenation reaction is preferably 30 to 150 ° C., and the pressure is preferably ^{2 to} 30 kg / cm ² .

  When the temperature of the hydrogenation reaction is within the above range, the reactivity is improved and a sufficient reaction yield can be obtained, and a side reaction due to thermal degradation of the polymer can be suppressed. When the pressure of the hydrogenation reaction is within the above range, the reaction rate is improved, the reaction time is shortened, and the cost of investing in the reactor can be suppressed, which is economically preferable.

[Step 2]
In the method for purifying a polymer solution of the present embodiment, step 2 is a step of adding and mixing an inorganic flocculant to the polymer solution obtained in step 1.

(Inorganic flocculant)
In general, metal residues such as a polymerization initiator and a hydrogenation catalyst contained in a polymer solution are characterized by small particles, and the small particles make it difficult to remove from the polymer solution. In step 2, an inorganic flocculant is added to and mixed with the polymer solution to agglomerate metal residues such as lithium and titanium to enlarge the particles. By enlarging the particles in this manner, the removal efficiency of the metal residue from the polymer solution can be increased.

  The inorganic flocculant used in the present embodiment is not particularly limited as long as it is generally used in this field. Aluminum sulfate, aluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, Examples thereof include magnesium oxide, magnesium carbonate, and magnesium sulfate. Inorganic flocculants include coagulable salts and polymer flocculants, but inorganic polymer flocculants are preferred. The inorganic polymer flocculant has a strong flocculating action and is excellent in the flocculating ability of the catalyst residue in the polymer solution. Examples of such inorganic polymer flocculants include polyaluminum chloride, polyaluminum sulfate, polyferric chloride, ferric sulfate, activated silicic acid, polysilica iron, and zeolite. In the present embodiment, among the inorganic flocculants, such inorganic polymer flocculants can be suitably used.

(Inorganic flocculant content)
The blending amount of the inorganic flocculant varies depending on the amount of the catalyst residue, but it is preferable to add 0.0001 to 10,000 mass times with respect to the catalyst residue to be removed, and 0.001 to 1,000 mass times. Is more preferable and 0.01-100 mass times is further more preferable. If the compounding amount of the inorganic flocculant is 0.0001 or more, a sufficient metal removal effect can be obtained. On the other hand, if the amount is 10,000 or less, it is preferable from the viewpoint of manufacturing cost.

(Inorganic flocculant addition method)
The method of adding the inorganic flocculant to the polymer solution is not particularly limited, and the inorganic flocculant may be added to the polymer solution as it is in the form of a solid, suspended in water, added, If it is a thing, you may add after making the state of aqueous solution. Among these, it is preferable to add with water from the viewpoint of the dispersibility of the inorganic flocculant.

(Organic polymer flocculant)
In the present embodiment, in Step 2, an organic polymer flocculant can be further added and mixed as necessary. The combined use of such an inorganic flocculant and an organic polymer flocculant can enhance the agglomeration effect of catalyst residues, that is, particles.

  The type of organic polymer flocculant is not particularly limited as long as it is generally used in this field, but it is not limited to carboxylic acid-based or sulfonic acid-based anionic polymer flocculants; acrylamide-based nonionic polymers. Examples include flocculants; acrylic acid ester-based and methacrylic ester-based cationic polymer flocculants; amphoteric polymer flocculants.

(Method of adding organic polymer flocculant)
The method for adding the organic polymer flocculant is not particularly limited, and the organic polymer flocculant may be added simultaneously with the inorganic flocculant, or the organic polymer flocculant may be added after the inorganic flocculant is added to the polymer solution. An inorganic flocculant may be added after the organic polymer flocculant is added to the solution. Among these, from the viewpoint of the coagulation effect of the catalyst residue, it is preferable to add the inorganic flocculant and thoroughly mix it before adding the organic polymer flocculant. Further, the organic polymer flocculant may be added to the polymer solution as a solid, or may be added in the form of an aqueous solution. Among these, addition from an aqueous solution is preferable from the viewpoint of dispersibility in a polymer solution.

(Amount of organic polymer flocculant)
Although the compounding quantity of an organic polymer flocculant is not specifically limited, It is preferable to add 0.001-1,000 mass times with respect to the compounding quantity of an inorganic flocculant, and 0.005-500 mass times is added. It is more preferable to add 0.01 to 100 times by mass. When the organic polymer flocculant is added, a good synergistic effect with the inorganic flocculant can be exerted by adding it in the above range. Thereby, the lithium residue and titanium residue in a polymer solution can be effectively aggregated and enlarged.

(Mixing method)
In this embodiment, the mixing method when an inorganic flocculant or an organic polymer flocculant is added to the polymer solution is not particularly limited. However, the higher the stirring effect, the shorter the mixing time, and the superior metal removal. It becomes a process. As an index of the stirring effect, a stirring strength P / V value (kW / m ³ ) can be mentioned. Here, P (kw) is the power required for stirring, and can be easily obtained by measuring the power consumption during mixing. V (m ³ ) is the spatial volume of the mixing part, and is the spatial volume of the part that gives a shearing force to the solution.

  The stirring strength P / V value is preferably 0.1 to 1,000,000, more preferably 100 to 500,000, and still more preferably 30,000 to 300,000. By setting the stirring intensity within the above range, the metal residues in the polymer solution can be efficiently aggregated in a short time, and the metal residues can be easily removed from the polymer solution. The stirring method is not particularly limited as long as the stirring strength is within the above range. For example, a method of applying a shearing force with a stirrer, a homogenizer including an emulsifier, a pump, a ball mill or a rod mill, or a high pressure A method of applying a collision force or friction force with a pulverizing roll or the like may be used.

  Among these, it is preferable to mix the inorganic flocculant, the organic polymer flocculant, or the inorganic flocculant and the organic polymer flocculant using an apparatus having a stirring strength P / V value of 100 or more. In this case, mixing of the polymer solution and the inorganic flocculant or organic polymer flocculant or inorganic flocculant and organic polymer flocculant can be sufficiently completed in a shorter time, for example, within 15 minutes. .

  Further, using a rotary disperser having a meshing structure having a stirring strength P / V value of 30,000 or more as described in JP-A-6-136034, an inorganic flocculant or an organic polymer flocculant or It is preferable to mix an inorganic flocculant and an organic polymer flocculant. In this case, mixing with a very high stirring strength is possible, and even within a short time, for example, within 10 seconds, the polymer solution and the inorganic flocculant or organic polymer flocculant or inorganic flocculant and organic polymer flocculant And the agent can be sufficiently mixed.

(Removal method)
In the present embodiment, the metal residue contained in the polymer solution is agglomerated and enlarged due to the effect of the inorganic flocculant added in step 2, and is easily removed. The method for removing the agglomerated and enlarged metal residue is not particularly limited as long as it is a method generally used in this field. For example, it can be easily removed by physical methods such as filtration, stationary separation, and centrifugation. Is possible. Among these, when water is used in the addition of the flocculant in Step 2, it is preferable to use a centrifuge. By using the centrifuge, water can be removed together with the enlarged catalyst residue, and the process can be simplified.

  In Step 2, an inorganic flocculant or an organic polymer flocculant can be added as it is without adding water or alcohol to the polymer solution. When water or alcohol is not added, a large-scale refining facility for reusing alcohol or water is unnecessary, and it may take a long time to separate the polymer solution from water or alcohol during the metal removal process. Absent. Therefore, an excellent metal removal process with little drainage can be provided. Even when an inorganic flocculant or an organic polymer flocculant is added as it is, it is possible to easily remove the agglomerated and enlarged metal residues by physical methods such as filtration, stationary separation, and centrifugation. .

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.

In this example, the following were used.
Inorganic flocculant 1 ... Polyaluminum chloride "Taipack" (Daimei Chemical Co., Ltd.)
Inorganic flocculant 2 ... Zeolite flocculant "Mizumu ST Series" (manufactured by Act Co., Ltd.)
Organic polymer flocculant: Polyacrylate "Himoloc MP-284"

[Production Example 1]
Polystyrene-polybutadiene-polystyrene block copolymer (styrene content: 30.0% by mass, butadiene content: 70.0% by mass, number average molecular weight: 50,000) by a conventionally known anionic polymerization method using alkyl lithium as an initiator. ) Was obtained. As a result of measuring the amount of metal contained in the polymer solution through elemental analysis (ICPS-7510, manufactured by Shimadzu Corporation) using inductively coupled plasma (ICP, Inductively coupled plasma). The amount of Li residue was 100 ppm.

[Production Example 2]
2800 g of a cyclohexane solution containing 400 g of the polystyrene-polybutadiene-polystyrene block copolymer obtained in Production Example 1 was placed in a 5-liter autoclave reactor and heated to 60 ° C. while stirring at 400 rpm. Thereafter, 1.5 mmol of triethylaluminum and 0.8 mmol of bis (cyclopentadienyl) titanium dichloride are added, and a hydrogenated polymer solution is obtained by pressurizing with 10 kg / cm ² of hydrogen to perform a hydrogenation reaction. Got. As a result of analyzing the hydrogenated polymer (polymer) by NMR, it was confirmed that 98% or more of the double bonds in the polybutadiene block were hydrogenated. The amount of metal contained in the obtained polymer solution was measured through elemental analysis using inductively coupled plasma (ICP), and as a result, Ti residue: 102 ppm, Li residue: 100 ppm, Al residue: 101 ppm. there were.

[Example 1]
In a mixer equipped with a stirrer, the polymer solution obtained in Production Example 1 and 0.2% by mass of inorganic flocculant 1 having the same volume of water as the polymer solution heated to 60 ° C. After mixing for 30 minutes (1800 seconds) at a P / V value of 0.5 kW / m ³ , the mixture was flowed into a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2. The polymer solution obtained was passed through at 0 T / hr and vacuum dried to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

[Example 2]
In a mixer equipped with a stirrer, in which the polymer solution obtained in Production Example 2 and 0.2% by mass of inorganic flocculant 1 and the same volume of water as the polymer solution are heated to 60 ° C. After mixing for 30 minutes (1800 seconds) at a P / V value of 0.5 kW / m ³ , the mixture was flowed into a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2. The polymer solution obtained was passed through at 0 T / hr and vacuum dried to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

Example 3
In a mixer equipped with a stirrer, in which the polymer solution obtained in Production Example 2 and 0.2% by mass of inorganic flocculant 1 and the same volume of water as the polymer solution are heated to 60 ° C. The mixture was mixed at a P / V value of 100 kW / m ³ for 10 minutes (600 seconds), and the mixed solution was supplied to a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2.0 T / The polymer solution obtained was passed through hr and vacuum-dried to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

Example 4
A rotary disperser having a meshing structure (Nikko Kogyo Co., Ltd.) containing the polymer solution obtained in Production Example 2 and 0.2% by mass of inorganic flocculant 1 and the same volume of water as the polymer solution. Manufactured by Cavitron 1010) and mixed at 60 ° C. and 7600 rpm for 0.1 second to obtain a mixed solution. The P / V value at this time was 3 × 10 ⁴ (kw / m ³ ). The obtained mixed liquid was allowed to stay in the tank for 5 minutes, and then passed through a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2.0 T / hr. The solution was vacuum dried to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

Example 5
With a stirrer in which the polymer solution obtained in Production Example 2 and water containing 0.5% by mass of the inorganic flocculant 2 are heated to 60 ° C. by 0.5 volume times water. The mixture was placed in a mixer and mixed at a P / V value of 0.5 kW / m ³ for 30 minutes (1800 seconds), and then a 0.2% by mass aqueous solution of organic polymer flocculant 1 was added to the polymer solution in an amount of 0.1%. The mixture was added 5 times by volume and mixed at a P / V value of 0.5 kW / m ³ for 30 minutes (1800 seconds). The obtained liquid mixture was passed through a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000G) at a flow rate of 2.0 T / hr, and the resulting polymer solution was vacuum-dried to obtain a solid. A polymer was obtained. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

Example 6
Mixing with a stirrer obtained by heating the polymer solution obtained in Production Example 2 and water containing 0.2% by mass of inorganic flocculant 2 to 0.5 volume times the polymer solution at 60 ° C. After mixing for 10 minutes (600 seconds) at a P / V value of 100 kW / m ³ , a 0.2% by weight aqueous solution of organic polymer flocculant 1 is further added to the polymer solution by 0.5 volume times. And mixed for 10 minutes at a P / V value of 0.5 kW / m ³ . The obtained liquid mixture was passed through a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000G) at a flow rate of 2.0 T / hr, and the resulting polymer solution was vacuum-dried to obtain a solid. A polymer was obtained. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

Example 7
Mixing with a stirrer obtained by heating the polymer solution obtained in Production Example 2 and water containing 0.2% by mass of inorganic flocculant 2 to 0.5 volume times the polymer solution at 60 ° C. After mixing for 10 minutes (600 seconds) at a P / V value of 100 kW / m ³ , a 0.2% by weight aqueous solution of organic polymer flocculant 1 is further added to the polymer solution by 0.5 volume times. The mixture was mixed for 0.1 second under conditions of 60 ° C. and 7600 rpm with a rotary disperser having a meshing structure (Cabitron 1010 manufactured by Nikko Industries) to obtain a mixed solution. The P / V value at this time was 3 × 10 ⁴ (kw / m ³ ). The obtained mixed liquid was allowed to stay in the tank for 5 minutes, and then passed through a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2.0 T / hr. The solution was vacuum dried to obtain a solid polymer.

Example 8
The polymer solution obtained in Production Example 2 and 2 mass times inorganic flocculant 2 with respect to the metal residue were added to the polymer solution, and the mixture was added to a mixer with a stirrer heated to 60 ° C. After mixing for 10 minutes (600 seconds) at a V value of 100 kW / m ³ , the resulting mixture was fed to a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2.0 T / hr. Then, the metal residue and the inorganic flocculant were removed from the polymer solution, and the resulting polymer solution was vacuum dried to obtain a solid polymer.

[Comparative Example 1]
Except that the inorganic flocculant 1 was not added, the same operation as in Example 2 was performed to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

[Comparative Example 2]
Except that the inorganic flocculant 1 was not added, the same operation as in Example 4 was performed to obtain a solid polymer. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

[Comparative Example 3]
The polymer solution obtained in Production Example 2 was directly passed through a centrifuge (a disk type centrifuge manufactured by Alfa Laval, relative centrifugal acceleration 3000 G) at a flow rate of 2.0 T / hr, and the resulting polymer solution was vacuumed. A solid polymer was obtained by drying. The amount of metal contained in the obtained solid polymer was measured through elemental analysis using inductively coupled plasma (ICP). The measurement results are shown in Table 1.

  The method for purifying a polymer solution of the present invention has industrial applicability as a method for removing a metal residue remaining in the polymer solution.

Claims (8)

Preparing a polymer solution containing at least lithium and / or titanium; and
And a step 2 of adding and mixing an inorganic flocculant to the polymer solution.   The method for purifying a polymer solution according to claim 1, wherein the polymer in the polymer solution is a conjugated diene polymer obtained by living anion polymerization.   The method for purifying a polymer solution according to claim 1 or 2, wherein the polymer solution further contains aluminum.   The method for purifying a polymer solution according to any one of claims 1 to 3, wherein in the step 2, the inorganic flocculant is mixed using an apparatus having a stirring strength P / V value of 100 or more.   5. The weight according to claim 1, wherein in the step 2, the inorganic flocculant is mixed using a rotary disperser having a meshing structure having a stirring strength P / V value of 30,000 or more. Purification method of the combined solution.   The method for purifying a polymer solution according to claim 1, wherein an organic polymer flocculant is further added and mixed in the step 2.   The method for purifying a polymer solution according to claim 6, wherein in the step 2, the organic polymer flocculant is mixed using an apparatus having a stirring strength P / V value of 100 or more.   The polymer according to claim 6 or 7, wherein in the step 2, the organic polymer flocculant is mixed using a rotary disperser having a meshing structure with a stirring strength P / V value of 30,000 or more. Solution purification method.