JP6690234B2 - Method for producing polymer - Google Patents

Description

  The present invention relates to an efficient method for producing a polymer of a conjugated diene monomer and / or an aromatic vinyl monomer, which is excellent in thermal stability, corrosion resistance and color tone.

The characteristics of the block copolymer formed by polymerizing the aromatic vinyl monomer and the conjugated diene monomer can be easily adjusted by adjusting the contents of the aromatic vinyl monomer and the conjugated diene monomer.
For example, when the content of aromatic vinyl monomer is relatively low, the block copolymer exhibits properties similar to vulcanized rubber at room temperature and properties similar to thermoplastic resin at high temperature. Can be one.
When the content of the aromatic vinyl monomer is relatively high, the block copolymer can be transparent and exhibit excellent properties such as impact resistance.

By the way, a block copolymer formed by polymerizing such an aromatic vinyl monomer and a conjugated diene monomer has problems such as a yellow color and a low color tone.
With respect to such a problem, Patent Documents 1 to 3 describe that various kinds of additives are added to the polymer solution after completion of the polymerization for treatment.

Japanese Patent Publication No. 54-2679 JP-A-62-232402 Japanese Patent Publication No. 3-60844

Although the color tone of the obtained polymer could be improved to some extent by the methods described in these patent documents, there is a problem that a polymer having excellent thermal stability cannot be obtained.
Further, the corrosion resistance of the polymer is insufficient, and further, although some improvement was recognized by the above-mentioned method, there is still a problem that the color tone of the polymer is insufficient.
As described above, there is a problem that a polymer excellent in corrosion resistance and color tone while being excellent in thermal stability has not been obtained yet.

  The present invention has been made in view of the above problems, and is excellent in thermal stability, corrosion resistance and color tone, and is an efficient polymer of a conjugated diene monomer and / or an aromatic vinyl monomer. The main purpose is to provide a manufacturing method.

  The present inventors have conducted extensive studies on a method of obtaining a polymer having excellent heat stability, corrosion resistance and color tone, and as a result, water and a polyvalent organic acid were added to the polymer solution, and then a predetermined amount of the polymer solution was added. After adding the phenolic antioxidant and the phosphorus antioxidant, the above object can be achieved by removing the solvent by steam stripping, further, depending on the addition timing of the surfactant, such as thermal stability. The present invention has been completed by finding that further improvement can be achieved.

  Thus, according to the present invention, a polymer obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer with an organolithium compound as an initiator in a hydrocarbon solvent or a hydrogenated product thereof is included. First step of adding water and a polyvalent organic acid having a solubility in water of more than 100 g / L to the polymer solution, and 100 parts by mass of the polymer or its hydrogenated product in the polymer solution after the first step. On the other hand, a second step of adding a phenol-based antioxidant in the range of 0.005 parts by mass to 5 parts by mass, and a phosphorus-based antioxidant in the range of 0.005 parts by mass to 5 parts by mass, A third step of removing the hydrocarbon solvent from the polymer solution after the second step by steam stripping to form a hydrous crumb, a fourth step of dehydrating the hydrous crumb after the third step, and the second step Before the process, above the second process and above Before the third step and at least one timing after the fourth step, 0.0001 parts by mass to 0.005 parts by mass of the nonionic surfactant with respect to 100 parts by mass of the polymer or its hydrogenated product. And a fifth step of adding within the range.

  The conjugated diene monomer is preferably at least one of butadiene and isoprene.

  The aromatic vinyl monomer is preferably styrene.

  The polymer or a hydrogenated product thereof is a block copolymer mixture containing a block copolymer A represented by the following formula (A) and a block copolymer B represented by the following formula (B), or a hydrogenated product thereof. It is preferable that it is a thing.

^{Ar1 a -D a -Ar2 a (A} )
_{^{(Ar b -D b) n X}} (B)

(Wherein, the Ar @ 1 ^a and Ar ^b, respectively the weight average molecular weight of an aromatic vinyl polymer block in the range of 6,000-20,000, Ar @ 2 ^a has a weight average molecular weight of 30,000～400, represents an aromatic vinyl polymer block in the range of 000, D ^a is a vinyl bond content represents a conjugated diene polymer block in the range of 1 mol% to 20 mol%, D ^b is a vinyl bond content Represents a conjugated diene block having a weight average molecular weight in the range of 20,000 to 200,000 in the range of 1 mol% to 20 mol%, X represents a single bond or a residue of a coupling agent, and n is 2 It is the above integer.)

  The polyvalent organic acid is preferably a hydroxycarboxylic acid.

  The hydroxycarboxylic acid is preferably an aliphatic hydroxycarboxylic acid.

  The aliphatic hydroxycarboxylic acid is preferably at least one selected from the group consisting of malic acid, citric acid and tartaric acid.

  Examples of the phosphorus-based antioxidant include tris (2,5-di-tert-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris [2,4-bis (1, 1-dimethylpropyl) phenyl] phosphite, tris (mono- or di-tert-butylphenyl) phosphite, 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecylphosphite ), Cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenylphosphite), and at least one selected from the group consisting of tris (nonylphenyl) phosphite. preferable.

  The nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether, polyoxyethylene alkyl ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene sorbitan. At least one selected from the group consisting of fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, alkylalkanolamide, and polyoxyethylene fatty acid ester is preferable.

  The amount of water added is in the range of 0.05 times to 1000 times mol with respect to the total amount of lithium atoms constituting the organolithium compound, and the amount of the polyvalent organic acid added is the amount of the organolithium compound. It is preferably in the range of 0.15 times to 0.5 times the molar amount of the total amount of the constituent lithium atoms.

  INDUSTRIAL APPLICABILITY The present invention has the effect of providing an efficient method for producing a polymer of a conjugated diene monomer and / or an aromatic vinyl monomer, which is excellent in thermal stability, corrosion resistance and color tone.

The present invention relates to a method for producing a polymer.
Hereinafter, the method for producing the polymer of the present invention will be described in detail.

  The method for producing a polymer of the present invention is a polymer obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer with an organic lithium compound as an initiator in a hydrocarbon solvent, or a hydrogenated product thereof. To a polymer solution containing water and a polyvalent organic acid having a solubility in water of more than 100 g / L, and to the polymer solution after the first step, the polymer or its hydrogenated product 100 is added. Second step of adding a phenol-based antioxidant within a range of 0.005 parts by mass to 5 parts by mass and a phosphorus-based antioxidant within a range of 0.005 parts by mass to 5 parts by mass with respect to parts by mass. A third step of removing the hydrocarbon solvent from the polymer solution after the second step by steam stripping to form a hydrous crumb, a fourth step of dehydrating the hydrous crumb after the third step, and Before the second step, after the second step Before the third step, and at least one timing after the fourth step, 0.0001 parts by mass to 0.005 parts by mass of the nonionic surfactant with respect to 100 parts by mass of the polymer or its hydrogenated product. And a fifth step of adding within the range of parts.

According to the present invention, the polymerization reaction in the polymer solution can be stopped by adding water in the first step.
Thus, in the production method of the present invention, the component added in the second step and the polymer having an active terminal before termination of polymerization or its hydrogenated product (hereinafter, may be simply referred to as a polymer). It is possible to suppress the occurrence of a coupling reaction with the active end or the like, and to prevent the structure of the polymer or the like from becoming uncontrollable.
Further, by adding the polyvalent organic acid in the first step, the polymerization reaction in the polymer solution can be stopped, and LiOH generated by the stopping reaction by the added water can be decomposed and removed. As a result, it is possible to prevent LiOH from reacting with carbon dioxide to form Li carbonate, which is a cause of precipitation and contamination of foreign matter, and the occurrence of discoloration by reacting with the phenolic antioxidant added in the second step. It becomes possible.
Further, when the polyvalent organic acid remains in the polymer or the like, the polyvalent organic acid may cause a corrosion problem in which the polymer or the like deteriorates with time. However, by using a highly water-soluble polyvalent organic acid having a solubility in water of more than 100 g / L as the polyvalent organic acid added in the first step, the production method of the present invention allows the hydrous crumb to be removed in the fourth step and the like. At the time of dehydration, the polyvalent organic acid can be easily discharged and removed together with the discharged water. As a result, the production method of the present invention makes it easy to obtain a polymer or the like with less corrosion defects. Further, as a result, the production method of the present invention makes it possible to easily obtain, for example, a polymer or the like that easily forms a film in which the generation of cracks is suppressed.

Further, the phenolic antioxidant and the phosphorus antioxidant added in the second step can improve the thermal stability of the polymer and the like. In particular, the phosphorus-based antioxidant that functions as the secondary antioxidant can be used in combination with the phenol-based antioxidant that functions as the primary antioxidant to synergistically improve the thermal stability of the polymer or the like.
In this way, by adding the above-mentioned two kinds of antioxidants in the second step, the production method of the present invention can be performed, for example, when the hydrous crumbs are dehydrated in the fourth step and after the fourth step. In the sixth step of further drying the water-containing crumb, etc., deterioration due to heat history and oxidative deterioration of the polymer and the like can be effectively prevented.

Furthermore, in the fifth step, a predetermined amount of a nonionic surfactant is added to improve the thermal stability of the resulting polymer and the like.
For example, when the nonionic surfactant is carried out before the second step, for example, when it is added to the polymer solution in the first step, that is, the polymer solution in the first step, The ionic surfactant can function as a neutralization aid that improves the reaction efficiency of the polyvalent organic acid added in the first step. Therefore, according to the production method of the present invention, lithium can be stably removed, and it is possible to obtain a polymer or the like having less foreign matter and excellent color tone.
When the nonionic surfactant is applied after the second step and before the third step, for example, when it is added to the polymer solution in the second step, that is, the polymer solution in the second step. In particular, the nonionic surfactant can improve the dispersibility of the polymer and the like. Therefore, in the production method of the present invention, for example, steam stripping in the third step is conveniently carried out, and a hydrous crumb having a uniform particle size can be obtained. Further, the improved granulation property makes it possible to smoothly proceed the subsequent sixth step and the like.
Further, when the nonionic surfactant is carried out after the above-mentioned fourth step, for example, when it is added to the hydrous crumb after dehydration in the fourth step, the nonionic surfactant is added to the hydrous water after dehydration. In the sixth step of further drying the crumb, it can function as an exothermic aid, and the drying becomes easy. Therefore, it becomes possible to achieve the drying conditions in the sixth step, for example, lowering the heating temperature and shortening the heating time. As a result, the production method of the present invention can suppress the deterioration of the polymer and the like due to the heat history and the oxidative deterioration in the sixth step, and it is possible to obtain the polymer and the like having excellent thermal stability and color tone.

  Thus, the first step and the second step described above are performed in this order before the third step of performing steam stripping, so that a polymer excellent in thermal stability, corrosion resistance, and color tone can be efficiently produced. Further, the thermal stability of the obtained polymer and the like can be further improved by the timing of performing the fifth step, that is, the timing of adding the nonionic surfactant.

The method for producing a polymer of the present invention has a first step, a second step, a third step and a fourth step in this order, and further has a fifth step.
Hereinafter, each step of the method for producing a polymer of the present invention will be described.

1. First Step The first step in the present invention is a polymer obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer with an organic lithium compound as an initiator in a hydrocarbon solvent or hydrogenation thereof. This is a step of adding water and a polyvalent organic acid having a solubility in water of more than 100 g / L to a polymer solution containing a substance.

(1) Polymer Solution The polymer solution contains a polymer or its hydrogenated product in a hydrocarbon solvent.

(A) Polymer or Hydrogenated Product Thereof The polymer used in this step is obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer with an organic lithium compound as an initiator in a hydrocarbon solvent. It is what is done.
Further, the hydrogenated product of the polymer is obtained by hydrogenating the above-mentioned polymer.
Here, the polymer or its hydrogenated product in this step is contained in the hydrocarbon solvent used for the polymerization of the polymer in a state having at least a part of active terminals.

Such a polymer may be a polymer obtained by polymerizing a conjugated diene monomer or a polymer obtained by polymerizing an aromatic vinyl monomer, and a conjugated diene monomer and It may be a random copolymer obtained by polymerizing an aromatic vinyl monomer or a block copolymer.
In the present invention, a polymer is obtained by polymerizing an aromatic vinyl polymer block composed of an aromatic vinyl monomer unit obtained by polymerizing an aromatic vinyl monomer as a main repeating unit, and a conjugated diene monomer. It is preferable that the block copolymer has at least one conjugated diene polymer block composed of the conjugated diene monomer unit obtained as the main repeating unit. Since the polymer is the above block copolymer, after being formed into a film, a high elastic modulus and a small permanent elongation are compatible at a high level, and further, a block copolymer that can be molded with good moldability. This is because it becomes easy to obtain a composition and a film obtained by molding the composition.
In the present specification, unless otherwise specified, the block copolymer is meant to include any of a pure block copolymer, a random block copolymer, and a copolymer having a tapered block structure. .
Hereinafter, the case where the polymer is the above block copolymer will be described in detail.

The aromatic vinyl polymer block contained in the block copolymer is a polymer block composed mainly of an aromatic vinyl monomer unit obtained by polymerizing an aromatic vinyl monomer.
Here, the aromatic vinyl monomer unit being constituted as a main repeating unit means that the content of the aromatic vinyl monomer unit in the aromatic vinyl polymer block is 50% by mass or more. is there.

  The content of the aromatic vinyl monomer unit in the aromatic vinyl polymer block is preferably 80% by mass or more, more preferably 90% by mass or more, and substantially 100% by mass. Particularly preferred.

The monomer constituting the aromatic vinyl monomer unit that can be contained in the aromatic vinyl polymer block is not particularly limited as long as it is an aromatic vinyl compound. Examples of the aromatic vinyl monomer include styrene; α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4. -Styrenes having an alkyl group as a substituent, such as diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene; 2-chlorostyrene, 3-chlorostyrene, Styrenes having a halogen atom as a substituent such as 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene and 2,4-dibromostyrene; 2-methyl-4,6-dichlorostyrene and the like. Styrenes having an alkyl group and a halogen atom as substituents; vinylnaphthalene; and the like.
Among these, from the viewpoint of easy availability, the aromatic vinyl monomer is preferably styrene or styrene having an alkyl group as a substituent, and particularly preferably styrene.
These aromatic vinyl monomers can be used alone or in combination of two or more.

The aromatic vinyl polymer block may contain other monomer units as long as the aromatic vinyl monomer unit is the main repeating unit.
Monomers constituting monomer units other than the aromatic vinyl monomer units that can be contained in the aromatic vinyl polymer block include 1,3-butadiene and isoprene (2-methyl-1,3-butadiene). Conjugated diene monomers such as acrylonitrile, methacrylonitrile and other α, β-unsaturated nitrile monomers; unsaturated carboxylic acid compounds such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid; maleic anhydride Unsaturated carboxylic acid anhydrides such as acids, butenyl succinic anhydride, tetrahydrophthalic anhydride, citraconic anhydride; methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, 2-methacrylic acid Unsaturated carboxylic acid ester monomers such as ethylhexyl; 1,4-pentadiene, 1,4-hexadiene And the like, preferably a non-conjugated diene monomer having a carbon number in the range of 5 to 12; and the like.

  When the block copolymer has a plurality of aromatic vinyl polymer blocks, the plurality of aromatic vinyl polymer blocks may be the same or different.

The content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer is not particularly limited, but is usually selected in the range of 10% by mass to 70% by mass, preferably 12% by mass to 60% by mass. It is selected in the range of mass%. When the content of the aromatic vinyl monomer unit in the block copolymer is in such a range, the polymer produced by the production method of the present invention has a high elastic modulus and a small permanent after being formed into a film. The elongation is compatible with each other at a high level, and a block copolymer composition that can be molded with good moldability, and a film obtained by molding this composition are easily obtained.
The content of the aromatic vinyl monomer unit in the block copolymer described in the present specification can be measured using proton NMR.

The conjugated diene polymer block included in the block copolymer is a polymer block composed mainly of a conjugated diene monomer unit obtained by polymerizing a conjugated diene monomer.
Here, the phrase "composed of a conjugated diene monomer unit as a main repeating unit" means that the content of the conjugated diene monomer unit in the conjugated diene polymer block is 50% by mass or more.

  The content of the conjugated diene monomer unit in the conjugated diene polymer block is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably substantially 100% by mass. . When the content of the conjugated diene monomer unit in the conjugated diene polymer block is in such a range, the polymer produced by the production method of the present invention has a high elastic modulus and a small permanent after being formed into a film. The elongation is compatible with each other at a high level, and a block copolymer composition that can be molded with good moldability, and a film obtained by molding this composition are easily obtained.

The conjugated diene monomer used for forming the conjugated diene polymer block is not particularly limited as long as it is a conjugated diene compound. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3- Hexadiene etc. can be illustrated.
Among these, the conjugated diene monomer is preferably at least one of 1,3-butadiene and isoprene, and particularly preferably isoprene.
By forming the conjugated diene polymer block with isoprene units, a block copolymer having excellent flexibility and a small permanent elongation can be obtained.
These conjugated diene monomers can be used alone or in combination of two or more in each conjugated diene polymer block. Further, in each conjugated diene polymer block, the same conjugated diene monomer may be used, or different conjugated diene monomers may be used. Furthermore, a hydrogenation reaction may be performed on a part of the unsaturated bonds of the conjugated diene polymer block.

  The conjugated diene polymer block may contain other monomer units as long as the conjugated diene monomer unit is the main repeating unit. Examples of the monomer constituting the monomer unit other than the conjugated diene monomer unit that can be contained in the conjugated diene polymer block include aromatic vinyl monomers such as styrene and α-methylstyrene, and α, β-unsaturated monomers. Examples thereof include saturated nitrile monomer, unsaturated carboxylic acid monomer, acid anhydride monomer, unsaturated carboxylic acid ester monomer, and non-conjugated diene monomer.

The vinyl bond content of the conjugated diene polymer block (the ratio of 1,2-vinyl bond and 3,4-vinyl bond in all conjugated diene monomer units in the conjugated diene polymer block) is not particularly limited. However, it is preferably within the range of 1 mol% to 20 mol%, more preferably within the range of 2 mol% to 15 mol%, and even more preferably within the range of 3 mol% to 10 mol%. Particularly preferred. If the vinyl bond content is too high, the polymer produced by the production method of the present invention may have a large permanent elongation.
The vinyl bond content of the conjugated diene polymer block described in this specification can be measured using proton NMR.

  When the block copolymer has a plurality of conjugated diene polymer blocks, the plurality of conjugated diene polymer blocks may be the same or different.

The weight average molecular weight of the block copolymer is not particularly limited, but is usually in the range of 50,000 to 500,000, preferably 70,000 to 470,000, and preferably 90,000 to More preferably, it is in the range of 450,000.
The weight average molecular weight of each polymer block of the block copolymer is not particularly limited, and the weight average molecular weight of the aromatic vinyl polymer block is usually within the range of 6,000 to 400,000, preferably 6, It is in the range of 000 to 370,000.
The weight average molecular weight of the conjugated diene polymer block is usually in the range of 20,000 to 400,000, preferably 35,000 to 350,000. When the weight average molecular weight of the conjugated diene polymer block is in such a range, the polymer produced by the production method of the present invention has a high elastic modulus and a small permanent elongation at a high level after being formed into a film. It is easy to obtain a block copolymer composition which is compatible with each other and can be molded with good moldability, and a film obtained by molding this composition.
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the block copolymer, polymer block and the like are obtained as polystyrene-converted values by measurement by high performance liquid chromatography.
More specifically, the weight average molecular weight and the number average molecular weight can be measured as a polystyrene reduced molecular weight by high performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The apparatus is HLC8320 manufactured by Tosoh Corporation, the column is three Shodex KF-404HQ manufactured by Showa Denko Co., Ltd. (column temperature 40 ° C.), the detector is a differential refractometer and an ultraviolet detector, and the molecular weight is calibrated by a polymer laboratory. It can be performed with 12 points of standard polystyrene (5 to 3 million) manufactured by the company.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the block copolymer and each polymer block constituting the block copolymer is not particularly limited. Are usually 1.1 or less, and preferably 1.05 or less. When the block copolymer, and the molecular weight distribution of each polymer block constituting the block copolymer is in such a range, the polymer produced by the production method of the present invention is high after molding into a film. The elastic modulus and the small permanent elongation are compatible at a high level, and further, it becomes easy to obtain a block copolymer composition that can be molded with good moldability, and a film obtained by molding this composition.

  The melt index of the block copolymer is not particularly limited, but is usually in the range of 1 g / 10 min to 1000 g / 10 min as a value measured according to ASTM D-1238 (G condition, 200 ° C., 5 kg). And is preferably in the range of 3 g / 10 minutes to 700 g / 10 minutes, and more preferably in the range of 5 g / 10 minutes to 500 g / 10 minutes. Within this range, the polymer produced by the production method of the present invention has particularly good moldability.

As long as the block copolymer has at least one aromatic vinyl polymer block and at least one conjugated diene polymer block, the number of each polymer block and the bonding form thereof are not particularly limited.
As a specific example of the form of such a block copolymer, Ar represents an aromatic vinyl polymer block, D represents a conjugated diene polymer block, X represents a single bond or a residue of a coupling agent, When n represents an integer of 2 or more, it is represented as an aromatic vinyl-conjugated diene block copolymer represented by Ar-D, Ar-D-Ar or (Ar-D) _n- X. Aromatic vinyl-conjugated diene-aromatic vinyl block copolymer, conjugated diene-aromatic vinyl-conjugated diene block copolymer represented by D-Ar-D or (D-Ar) _n- X, Ar-D -Aromatic vinyl-conjugated diene-aromatic vinyl-conjugated diene block copolymer represented by -Ar-D, and a mixture of block copolymers obtained by mixing two or more of these in any combination. Examples thereof include, but are not limited to.

Among these, as the block copolymer particularly preferably used in the present invention, an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer represented by Ar-D-Ar or (Ar-D) _n -X. And a block copolymer mixture containing a block copolymer A represented by the following formula (A) and a block copolymer B represented by the following formula (B) is particularly preferable. .
That is, in this step, as a polymer or a hydrogenated product thereof, a block containing a block copolymer A represented by the following formula (A) and a block copolymer B represented by the following formula (B) It is preferable to use a copolymer mixture or a hydrogenated product thereof.
By using the above block copolymer mixture as the block copolymer, it is possible to impart a higher elastic modulus and a smaller permanent elongation to the polymer produced by the production method of the present invention.

^{Ar1 a -D a -Ar2 a (A} )
_{^{(Ar b -D b) n X}} (B)

(Wherein, the Ar @ 1 ^a and Ar ^b, respectively the weight average molecular weight of an aromatic vinyl polymer block in the range of 6,000-20,000, Ar @ 2 ^a has a weight average molecular weight of 30,000～400, represents an aromatic vinyl polymer block in the range of 000, D ^a is a vinyl bond content represents a conjugated diene polymer block in the range of 1 mol% to 20 mol%, D ^b is a vinyl bond content Represents a conjugated diene block having a weight average molecular weight in the range of 20,000 to 200,000 in the range of 1 mol% to 20 mol%, X represents a single bond or a residue of a coupling agent, and n is 2 It is the above integer.)

In the above formula ^(A), Ar1 ^a is an aromatic vinyl polymer block in the range of weight average molecular weight of 6,000-20,000, Ar @ 2 ^a has a weight average molecular weight of 30,000～400,000 an aromatic vinyl polymer block in the range of, D ^a is a vinyl bond content of the conjugated diene polymer block in the range of 1 mol% to 20 mol%.

The block copolymer A, as represented by the above formula (A), a relatively small aromatic vinyl polymer block having a weight average molecular weight (Ar @ 1 ^a), a conjugated diene heavy with specific vinyl bond content Asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block co-polymer composed of ^a merged block (D ^a ) and an aromatic vinyl polymer block (Ar2 ^a ) having a relatively large weight average molecular weight in this order. It is united.

The weight average molecular weight (Mw (Ar1 ^a )) of the aromatic vinyl polymer block (Ar1 ^a ) having a relatively small weight average molecular weight is in the range of 6000 to 20,000 and in the range of 7,000 to 18,000. Is preferred.
When Mw (Ar1 ^a ) is out of this range, the polymer produced by the production method of the present invention may have insufficient permanent elongation.

The weight average molecular weight of the aromatic vinyl polymer block (Ar @ 2 ^a) having a relatively large weight average molecular weight (Mw ^(Ar2 a)) is in the range of 30,000～400,000, 32,000～ It is preferably in the range of 370,000, and more preferably in the range of 35,000 to 350,000. If Mw (Ar2 ^a ) is too small, the polymer produced by the production method of the present invention may have insufficient permanent elongation, and the block copolymer A having too large Mw (Ar2 ^a ) is produced. Can be difficult.

In the block copolymer A, the weight average molecular weight (Mw (Ar2 ^a )) of the aromatic vinyl polymer block (Ar2 ^a ) having a relatively large weight average molecular weight and the aromatic vinyl polymer weight having a relatively small weight average molecular weight the ratio of the weight average molecular weight of polymer block ^{(Ar1 a) (Mw (Ar1} a)) (Mw (Ar2 a) / Mw (Ar1 a)) is not particularly limited, usually, in the range of 2.2 to 67 And preferably in the range of 2.6 to 67, more preferably in the range of 3 to 40, and particularly preferably in the range of 3.4 to 35.
By constituting the block copolymer A in this way, the polymer produced by the production method of the present invention has a lower permanent elongation and a higher elastic modulus, and is a block copolymer composition rich in elasticity. You can get things.

The vinyl bond content of the conjugated diene polymer block ( ^Da ) of the block copolymer A (the ratio of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) is 1 It is in the range of mol% to 20 mol%, preferably in the range of 2 mol% to 15 mol%, and more preferably in the range of 3 mol% to 10 mol%. If the vinyl bond content is too high, the polymer produced by the production method of the present invention may have a large permanent elongation.

The weight average molecular weight (Mw (D ^a )) of the conjugated diene polymer block (D ^a ) of the block copolymer A is not particularly limited, but is usually in the range of 20,000 to 200,000, 30, It is preferably in the range of 000 to 150,000, and more preferably in the range of 35,000 to 100,000.

The content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer A is not particularly limited, but is usually in the range of 40% by mass to 90% by mass, and 45% by mass to 87% by mass. %, And more preferably 50% to 85% by mass.
The weight average molecular weight of the block copolymer A as a whole is not particularly limited, but is usually in the range of 50,000 to 500,000, preferably in the range of 70,000 to 470,000, More preferably, it is in the range of 90,000 to 450,000.

The block copolymer B, which is the other of the two block copolymers constituting the block copolymer mixture, is an aromatic compound having a specific weight average molecular weight, as represented by the above formula (B). Two or more diblock products (Ar ^b -D ^b ) formed by bonding a vinyl polymer block (Ar ^b ) and a conjugated diene polymer block (D ^b ) having a specific vinyl bond content, aromatic It is a block copolymer constituted by direct bonding via a single bond or via a residue of the coupling agent (X) so that the vinyl polymer block (Ar ^b ) side is the terminal.

In the above formula (B), Ar ^b is an aromatic vinyl polymer block having a weight average molecular weight of 6,000 to 20,000, and D ^b has a vinyl bond content of 1 mol% to 20 mol. % Of the conjugated diene polymer block having a weight average molecular weight of 20,000 to 200,000. X represents a single bond or a residue of a coupling agent, and n is an integer of 2 or more.

Examples of the coupling agent that constitutes the residue of the coupling agent include those described below. The number (that is, n in the formula (B)) bonded to the diblock body (Ar ^b -D ^b ) is not particularly limited as long as it is 2 or more, and the block copolymer B in which the diblock body is bonded at a different number. May be mixed. Although n in formula (B) is not particularly limited as long as it is an integer of 2 or more, it is generally an integer in the range of 2 to 8, and preferably an integer in the range of 2 to 4.

The weight average molecular weight (Mw (Ar ^b )) of the aromatic vinyl polymer block (Ar ^b ) in which the block copolymer B has two or more in one molecule is in the range of 6000 to 20,000, respectively. It is preferably in the range of 7,000 to 18,000, and more preferably in the range of 8,000 to 15,000. When Mw (Ar ^b ) is out of this range, the polymer produced by the production method of the present invention may have too large a permanent elongation.
The weight average molecular weights (Mw (Ar ^b )) of the aromatic vinyl polymer blocks present in two or more in one molecule of the block copolymer B are the same or different from each other within the above range. They may be present, but it is preferable that they are substantially equal. The weight average molecular weight (Mw (Ar ^b )) of these aromatic vinyl polymer blocks is the weight average molecular weight of the aromatic vinyl polymer block (Ar1 ^a ) having a relatively small weight average molecular weight of the block copolymer A. More preferably, it is substantially equal to the molecular weight (Mw (Ar1 ^a )).

The vinyl bond content of the conjugated diene polymer block (D ^b ) of the block copolymer B is in the range of 1 mol% to 20 mol%, preferably 2 mol% to 15 mol%. More preferably, it is within the range of 3 mol% to 10 mol%. If the vinyl bond content is too high, the polymer produced by the production method of the present invention may have a large permanent elongation.
The vinyl bond content of the conjugated diene polymer block (D ^b ) of the block copolymer B is substantially equal to the vinyl bond content of the conjugated diene polymer block (D ^a ) of the block copolymer A. Is preferred.

The weight average molecular weight of the conjugated diene polymer block ^{(D b)} of the block copolymer B ^{(Mw (D} b)) is in the range of 20,000 to 200,000, a range of 25,000～150,000 It is preferably within the range of 30,000 to 100,000, and more preferably within the range of 30,000 to 100,000.
The weight average molecular weight of the conjugated diene polymer block ^{(D b) (Mw (D} b)) by is in this range, the polymer produced by the production method of the present invention, a higher modulus and lower elongation set And has a high elasticity.

Further, the weight average molecular weight (Mw (D ^b )) of the conjugated diene polymer block (D ^b ) of the block copolymer B is the weight average molecular weight of the conjugated diene polymer block (D ^a ) of the block copolymer A ( Mw ^(D a)) and the ratio of ^{(Mw (D b) / Mw} (D a)) is preferably at which the range of 1.1 to 10, and in the range of 1.3 to 5 It is more preferable that it is in the range of 1.5 to 3, and it is particularly preferable that it is in the range of 1.5 to 3.
By setting the value of Mw (D ^b ) / Mw (D ^a ) in this way, the polymer produced by the production method of the present invention has a higher elastic modulus and is rich in elasticity.

The content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer B is not particularly limited, but is usually in the range of 10% by mass to 35% by mass, and 12% by mass to 32% by mass. %, And more preferably 15% to 30% by mass.
The weight average molecular weight of the block copolymer B as a whole is not particularly limited, but is usually in the range of 60,000 to 800,000, preferably in the range of 80,000 to 600,000. More preferably, it is in the range of 100,000 to 400,000.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the block copolymer A, the block copolymer B, and the polymer blocks constituting them is Although not particularly limited, each is usually 1.1 or less, preferably 1.05 or less.

  The mass ratio (A / B) between the block copolymer A and the block copolymer B is usually within the range of 36/64 to 85/15, and within the range of 38/62 to 80/20. Preferably, it is more preferably within the range of 40/60 to 75/25. By containing each block copolymer in such a ratio, the polymer produced by the production method of the present invention tends to have both a high elastic modulus and a small permanent elongation. If this ratio is too small, the elastic modulus of the polymer produced by the production method of the present invention will be insufficient, and if this ratio is too large, the permanent elongation of the polymer will tend to be large.

(B) Polymer Solution The polymer solution used in this step contains a polymer or its hydrogenated product in a hydrocarbon solvent.
The inclusion in the hydrocarbon solvent is not limited to a state in which the polymer or the like is dissolved in the hydrocarbon solvent, but may be a state in which the polymer or the like is insoluble in the hydrocarbon solvent and is in a suspended state. .

  Such a hydrocarbon solvent is not particularly limited as long as it can dissolve the conjugated diene monomer and / or the aromatic vinyl monomer and is inert to the organolithium polymerization initiator, and, for example, Aliphatic hydrocarbons (eg, butane, butene-1, cis-butene-2, pentane, isopentane, hexane, heptane, octane), alicyclic hydrocarbons (eg, cyclopentane, cyclohexane), aromatic hydrocarbons (eg, , Benzene, toluene, xylene) and the like, and one kind or a mixture of two or more kinds can be used.

The content of the hydrocarbon solvent in the polymer solution may be such that the conjugated diene monomer and / or the aromatic vinyl monomer can be stably polymerized, and the polymer or its hydrogenated product 100 mass It can be in the range of 50 parts by mass to 2000 parts by mass with respect to parts.
In addition, with respect to 100 parts by mass of the polymer or its hydrogenated product, when the polymer contained in the hydrocarbon solvent is a hydrogenated product of the polymer, the mass of the polymer with respect to 100 parts by mass of the hydrogenated product. It represents a ratio.

(C) Method for forming polymer or hydrogenated product thereof As a method for forming the polymer, a desired polymer can be obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer. Any known method may be used as long as it can be used.
Here, as a polymerization method for polymerizing the conjugated diene monomer and / or the aromatic vinyl monomer, for example, an anion polymerization method using an organic lithium compound in a hydrocarbon solvent can be used.

The organolithium compound used as an initiator in the polymerization of the polymer may be any one capable of polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer in a hydrocarbon solvent, for example, a monolithium compound. And polylithium compounds, such as ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, oligobutadienyl dilithium, oligoisoprenyl dilithium. Examples thereof include lithium and oligostyryldilithium, which can be used alone or in combination of two or more.
The amount of the organolithium compound used can be appropriately adjusted according to the molecular weight of the target polymer based on a conventional method.

Further, the polymerization conditions can be appropriately set according to the molecular weight of the polymer and the like. The polymerization temperature can be, for example, usually in the range of -20 ° C to 150 ° C, preferably in the range of 30 ° C to 120 ° C. The pressure is, for example, selected from the range in which the hydrocarbon solvent and the monomer are maintained in the liquid phase within the above-mentioned polymerization temperature range, and is not particularly limited.
Although the polymerization time varies depending on the conditions such as the polymerization temperature, it is generally 24 hours or less, preferably 1 hour to 10 hours.

As the method for forming the above-mentioned polymer, specifically, when the polymer is a block copolymer having both an aromatic block and a conjugated diene block, JP-B-36-19286 and JP-B-43- The methods disclosed in Japanese Patent Publication No. 17979, Japanese Patent Publication No. 46-32415, Japanese Patent Publication No. 48-4106, Japanese Patent Publication No. 50-5037, Japanese Patent Publication No. 58-10412 and the like can be used.
More specifically, the polymer is a block copolymer mixture containing the block copolymer A and the block copolymer B described above, and when n of the block copolymer B is 2, the above formation is performed. As the method, a method of carrying out the following steps (a) to (d) in this order can be used (for details of the reaction, WO 2009/123089 pamphlet, JP 2012-77158 A, etc.). See).
The block copolymer mixture formed by such a forming method usually contains the block copolymer A having an active terminal.

(A): A step (a) of polymerizing an aromatic vinyl monomer using an organic lithium compound in a hydrocarbon solvent.
(B): A step (b) of adding a conjugated diene monomer to the polymer solution containing the aromatic vinyl polymer having an active terminal obtained in the step (a).
(C): Amount of the functional group in the polymer solution containing the aromatic vinyl-conjugated diene block copolymer having an active end obtained in the above step (b) is less than 1 molar equivalent of the functional group with respect to the active end. Step (c) of forming a block copolymer B by adding a bifunctional coupling agent of
(D): A step (d) of forming a block copolymer A by adding an aromatic vinyl monomer to the polymer solution obtained in the step (c).

The coupling agent added in step (c) is not particularly limited as long as it is bifunctional, and examples thereof include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane and dimethyldichlorosilane; dichloroethane and dibromo. Bifunctional halogenated alkanes such as ethane, methylene chloride and dibromomethane; Bifunctional halogenated alkanes such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin and dibutyldichlorotin Tin; and the like.
These coupling agents may be used alone or in combination of two or more.

  The amount of the coupling agent to be added is determined according to the ratio of the block copolymer A and the block copolymer B constituting the block copolymer mixture, and the functional group is 1 to the active terminal of the polymer. It is not particularly limited as long as it is less than the molar equivalent, but it is usually in the range of 0.15 to 0.90 molar equivalent of the functional group of the bifunctional coupling agent with respect to the active end of the polymer. , 0.20 molar equivalent to 0.70 molar equivalent.

In the present invention, the hydrogenated product of the polymer is obtained by hydrogenating the polymer obtained by the method for forming a polymer described above.
As the catalyst and the hydrogenation method used in the hydrogenation reaction, known catalysts and methods can be used, and for example, the same as the contents described in JP-A-1-182307.

(2) Addition of water and polyvalent organic acid In this step, the water added to the polymer solution is used for deactivating the activity of the polymer having active terminals and for stopping the polymerization reaction. .
The amount of such water to be added may be such that the polymerization reaction can be sufficiently stopped, and for example, is 0.05 times mol to the total amount of lithium atoms constituting the organolithium compound used as the initiator. It can be in the range of 1000 times by mole, preferably in the range of 0.5 times by mole to 500 times by mole, and particularly preferably in the range of 5 times by mole to 100 times by mole. This is because water can stably stop the polymerization reaction when the addition amount is within the above range. As a result, the polymer and the like produced by the production method of the present invention have excellent color tone and the like.

The polyvalent organic acid added to the polymer solution in this step is used to remove lithium derived from the organolithium compound added as an initiator.
Further, the polyvalent organic acid has a solubility in water of more than 100 g / L.

As such a polyvalent organic acid, any polyvalent organic acid may be used as long as it has two or more acidic groups and exhibits the above-mentioned solubility, and examples thereof include a hydroxycarboxylic acid having a hydroxyl group such as malic acid and tartaric acid, and oxalic acid. Examples thereof include dicarboxylic acids such as maleic acid and tricarboxylic acids such as aconitic acid, and of these, hydroxycarboxylic acid is preferable.
As the hydroxycarboxylic acid, one having a hydroxyl group and two or more carboxyl groups can be used. For example, an aromatic hydroxycarboxylic acid having these functional groups bonded to an aromatic ring may be used. An aliphatic hydroxycarboxylic acid having a functional group bonded to a chain hydrocarbon group such as an alkyl group is preferable, and malic acid, citric acid, and tartaric acid are particularly preferable. This is because the hydroxycarboxylic acid has excellent solubility in water, is effective in stopping the polymerization reaction in the polymer solution, and has good LiOH neutralization reactivity. Hydroxycarboxylic acid forms Li and hydroxycarboxylic acid Li and can be removed with water. Therefore, the production method of the present invention makes it possible to easily obtain a polymer having a small amount of polyvalent organic acid remaining. Further, as a result, the polymer and the like produced by the production method of the present invention have excellent color tone and the like.

  The addition amount of the polyvalent organic acid, as long as it can sufficiently remove the lithium derived from the organolithium compound used as the initiator present in the polymer solution, of the lithium atoms constituting the organolithium compound The total amount is preferably in the range of 0.15 times to 0.5 times the molar amount, particularly preferably in the range of 0.20 times to 0.475 times the molar amount, particularly preferably It is preferably in the range of 0.25 times to 0.45 times the mole. This is because the polyvalent organic acid can stably remove lithium derived from the organolithium compound used as the initiator when the addition amount is within the above range. Further, in the production method of the present invention, since the polyvalent organic acid used is water-soluble, it is easily removed during the dehydration in the fourth step, and a polymer having a small amount of residual polyvalent organic acid is easily obtained. Because you can. Further, as a result, the polymer or the like produced by the production method of the present invention has excellent color tone and the like.

  In this step, other components may be added to the polymer solution, if necessary, in addition to water and polyvalent organic acid.

The addition rate of each component added to the polymer solution in this step may be such that the entire amount is added all at once to the reactor, or may be added continuously or in portions.
In this step, the components added to the polymer solution may be added at the same timing or at different timings.
When the addition timing between each of the above components is the same, as a method of adding each component, a method of preparing after adding a liquid in which each component is mixed, or a method of simultaneously adding from different lines is adopted. can do.
Further, the method of adding the above-mentioned respective components may be a method of directly adding the respective components to the polymer solution, or a method of dissolving them in a hydrocarbon solvent prepared separately and then adding them.

2. Second Step In the second step of the present invention, 0.005 parts by mass to 5 parts by mass of a phenolic antioxidant is added to 100 parts by mass of the polymer or its hydrogenated product in the polymer solution after the first step. Parts, and a step of adding the phosphorus-based antioxidant in the range of 0.005 parts by mass to 5 parts by mass.

The phenolic antioxidant is used for improving the thermal stability of the obtained polymer and the like.
As such a phenolic antioxidant, a conventionally known one can be used.
Suitable phenolic antioxidants include, for example, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, tetrakis (methylene-3- ( 3 ', 5'-di-tert-butyl-4'-hydroxyphenylpropionate) methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-) Hydroxybenzyl) benzene, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, octadecyl-3- (3,3 5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol bis (3- (3-tert-butyl-5-methyl-4-hydroxy) Phenyl) propionate), 1,3,5-tris- (4-tert-butyl-3-hydroxy-2.6-dimethylbenzyl) isocyanuric acid, 2,2'-methylene-bis (4-methyl-6-tert). -Butylphenol), 3,9-bis (2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10 -Tetraoxaspiro [5,5] undecane, 4-hydroxymethyl-2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, butylated hydroxyanisole, 2,2 '-Dihydroxy-3,3'-dicyclohexyl-5,5'-dimethyl-diphenylmethane, 1,1,3-tris (2-methyl-4-hydroxy) -5-tert-butylphenyl) butane, 4,4'-butylidene-bis (6-tert-butyl-m-cresol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), bis ( 3-cyclohexyl-2-hydroxy-5-methylphenyl) methane, 1,1-bis (2'-methyl-4'-hydroxy-5'-tert-butylphenol), etc., and one kind or a mixture of two or more kinds. This is because the above-mentioned phenolic antioxidant is excellent in imparting thermal stability to the polymer and the like.

  The amount of the phenolic antioxidant added may be in the range of 0.005 parts by mass to 5 parts by mass with respect to 100 parts by mass of the polymer or its hydrogenated product, but 0.01 parts by mass to 3 parts. It is preferably in the range of parts by mass, and more preferably in the range of 0.015 parts by mass to 1 part by mass. When the addition amount is within the above range, the phenolic antioxidant can make the polymer and the like excellent in thermal stability.

  The phosphorus-based antioxidant is used for improving the thermal stability of the obtained polymer and the like.

As such a phosphorus-based antioxidant, a conventionally known one can be used.
In this step, the phosphorus-based antioxidant is preferably a non-hydrolyzable one that does not increase in weight due to hydrolysis for 300 hours or longer at 50 ° C. and 90% RH. Since the phosphorus-based antioxidant added in this step is non-hydrolyzable, generation of strong acid in the polymer can be suppressed. Further, when such a strong acid remains in a polymer or the like, it causes corrosion such that the polymer or the like deteriorates with time, and causes, for example, cracking of a film formed using the polymer or the like. Therefore, by using a non-hydrolyzable phosphorus-based antioxidant as the phosphorus-based antioxidant, the production method of the present invention is excellent in corrosion resistance, for example, a film in which the occurrence of cracks is suppressed. It is possible to easily obtain a polymer or the like that is easy to form.
Examples of the phosphorus-based antioxidant include tris (2,5-di-tert-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, and tris [2,4-bis]. (1,1-Dimethylpropyl) phenyl] phosphite, tris (mono- or di-tert-butylphenyl) phosphite, 4,4′-butylidene-bis (3-methyl-6-t-butylphenyl-di-tri Decylphosphite), cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenylphosphite), tris (nonylphenyl) phosphite, etc., and one or more It can be mixed and used. This is because the above phosphorus-based antioxidant is excellent in imparting thermal stability to the polymer and the like.
Further, in this step, non-hydrolyzable tris (2,4-di-tert-butylphenyl) phosphite and the like can be preferably used among the above phosphorus-based antioxidants.

  The addition amount of the phosphorus-based antioxidant may be within the range of 0.005 parts by mass to 5 parts by mass with respect to 100 parts by mass of the polymer or its hydrogenated product, but 0.01 parts by mass to 3 parts. It is preferably in the range of parts by mass, and more preferably in the range of 0.015 parts by mass to 1 part by mass. When the addition amount is within the above range, the phosphorus-based antioxidant can make the polymer or the like excellent in thermal stability.

  In this step, in addition to the phenol-based surfactant and the phosphorus-based surfactant, other components may be added to the polymer solution as needed.

  The addition rate, addition timing, addition method, and the like of each component added to the polymer solution in this step can be the same as those described in the above section "1. First step".

3. Third Step The third step of the present invention is a step of forming a hydrous crumb by removing the hydrocarbon solvent from the polymer solution after the second step by steam stripping.

In this step, the hydrocarbon solvent is removed from the polymer solution by steam stripping, so that the polymer or its hydrogenated product can be separated as an aqueous slurry-containing water-containing crumb.
As a method of steam stripping in this step, a conventionally known method can be used. In the above method, for example, the concentration of the polymer or the hydrogenated product of the polymer solution after the second step is adjusted within a range of 10% by mass to 50% by mass by any means, and the polymer solution after the concentration is adjusted. It is possible to use a method in which the hydrocarbon solvent is distilled off together with the steam by stirring and heating while blowing the steam into.
The heating temperature may be the boiling point of the hydrocarbon solvent or a temperature above the azeotropic temperature of water with it.

The content of the hydrocarbon solvent in the hydrous crumb formed in this step can be, for example, less than 1 part by mass per 100 parts by mass of the polymer or its hydrogenated product.
The water content of the water-containing crumb can be in the range of 80% by mass to 99.9% by mass, and is preferably in the range of 90% by mass to 99% by mass. This is because when the water content is within the above range, the water-containing crumb having a good particle size can be obtained in this step.

4. Fourth Step The fourth step in the present invention is a step of dehydrating the hydrous crumb after the third step.

The dehydration method from the hydrous crumb in this step may be any method capable of dehydrating the hydrous crumb to a desired water content, and a general dehydration method for the hydrous crumb can be used, for example, JP-A-1-182307. The methods described in the official gazette, JP-A-7-70265 and the like can be used.
Specifically, as a dehydration method, first, a water-containing crumb is subjected to a drainage treatment using a vibration screen, a centrifugal dehydrator or the like to have a water content in the range of 30% by mass to 60% by mass, and further, a roll. A method of dehydrating the water content to a level within the range of 1% by mass to 20% by mass by compression dehydration treatment with a compression dehydrator such as a Banbury type dehydrator or a screw type extruder type squeezing dehydrator can be used.

  The water content of the hydrous crumb after dehydration obtained in this step may be one that can achieve a desired amount of residual lithium or the like, and can be in the range of 1% by mass to 20% by mass, and 2% by mass. % To 10% by mass is preferable. This is because when the water content is within the above range, the residual amount of lithium can be sufficiently reduced. Further, it is possible to shorten the processing time, suppress gelation of the polymer, and relax the drying condition in the sixth step described later.

5. Fifth step The fifth step in the present invention is 100 mass of the polymer or hydrogenated product thereof at least at one timing before the second step, after the second step, before the third step, and after the fourth step. Is a step of adding a nonionic surfactant within a range of 0.0001 parts by mass to 0.005 parts by mass with respect to parts by mass.

The execution timing of this step may be at least one timing before the second step, after the second step, before the third step, and after the fourth step, and may be any one timing. , May be performed at all timings.
In this step, above all, it is preferable that the execution timing includes at least after the fourth step, and in particular, at all timings, that is, before the second step, after the second step and before the third step, and It is preferable to carry out at a timing after the fourth step. By including at least after the fourth step, it becomes possible to effectively exhibit the function of the nonionic surfactant as a heat generation aid. Therefore, the production method of the present invention makes it possible to easily obtain a polymer having excellent thermal stability and the like.
Further, since the present step is carried out at the timing before the second step and after the second step and before the third step, the production method of the present invention further provides a polymer excellent in granulation property, color tone and the like. This is because it is possible to easily obtain the above.

The term "before the second step" means the polymer solution before the first step, the polymer solution during the first step, and the step after the first step, which is the timing of addition to the polymer solution before the second step.
In this step, it is particularly preferable that the addition timing before the second step is the timing of addition to the polymer solution during the first step.
Further, “after the second step and before the third step” means the timing of adding the polymer solution during the second step and after the second step to the polymer solution before the third step.
Further, “after the fourth step” means adding to the hydrous crumb after the fourth step, that is, after the dehydration, usually after the fourth step and before the sixth step described later. It is time to add to the hydrous crumbs.

As such a nonionic surfactant, a conventionally known surfactant having a hydrophilic group that does not ionize in pure water and a lipophilic group can be used.
Examples of the hydrophilic group include a hydroxyl group and an amide group, and examples of the lipophilic group include an alkyl group, an alkenyl group, a cycloalkyl group and an aryl group.
As a suitable nonionic surfactant, more specifically, known polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether, polyoxyethylene alkyl ester, sorbitan fatty acid ester, Polyoxyethylene alkylamine, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, alkyl alkanolamide, polyoxyethylene fatty acid ester can be used alone or in combination of two or more. . This is because the above-mentioned nonionic surfactant is excellent in improving dispersibility in a polymer and the like, imparting a function as a heat generation aid, a function as a neutralization aid, and the like.

The addition amount of the nonionic surfactant may be within the range of 0.0001 parts by mass to 0.005 parts by mass with respect to 100 parts by mass of the polymer or its hydrogenated product, but 0.0002 parts by mass. It is preferably in the range of 0.003 parts by mass to 0.0045 parts by mass, and more preferably in the range of 0.0003 parts by mass to 0.004 parts by mass. By the addition amount is within the above range, the nonionic surfactant is easy to improve the dispersibility in the polymer and the like, function as a heat generation aid, and impart a function as a neutralization aid. Because it will be.
In addition, the said addition amount says the addition amount for each timing, when this process is implemented at two or more timings. For example, when the execution timing of this step is three times before the second step, after the second step, before the third step, and after the fourth step, the above-mentioned addition amount at each timing. The nonionic surfactant is added.

6. Other Steps The production method of the present invention has the first step to the fifth step, but may have other steps as necessary.
Such other steps usually include a sixth step of further drying the hydrous crumb after the fourth step.

The drying method in the sixth step may be any method as long as it can dry the water-containing crumb after the fourth step to a desired water content, and examples thereof include a heat-drying method of evaporating and removing water contained in the water-containing crumb by heating. be able to.
A known method can be used as the heating and drying method, and examples thereof include a method using a hot air dryer, an extrusion dryer, and an expansion dryer.
In the present step, in particular, when the execution timing of the fifth step is after the fourth step, the drying method is a method using an extrusion dryer for heating and compressing the water-containing crumb to remove water. It is preferable. This is because when the above-mentioned drying method is the above-mentioned method, the function of the nonionic surfactant added in the fifth step as a heat generating aid can be effectively exhibited.

  The water content of the polymer or the hydrogenated product thereof obtained in the sixth step may be such that the desired moldability of the polymer or the like can be obtained, and can be, for example, less than 1% by mass. This is because when the water content is within the above range, it is possible to shorten the processing time, suppress gelation of the polymer, and the like.

7. Method for Producing Polymer The polymer or a hydrogenated product thereof obtained by the method of the present invention has a small residual amount of lithium derived from the organolithium compound used as the initiator.
The residual amount of lithium in such a polymer or a hydrogenated product thereof can be less than 50 ppm, preferably less than 40 ppm, and particularly preferably 30 ppm or less. When the residual amount is within the above range, the polymer or the like has excellent color tone.
The residual amount of lithium in the polymer or its hydrogenated product can be measured using ICP-MS (Agilent 7500cs).
As the measurement procedure, after dissolving the polymer or its hydrogenated product in nitric acid, the polymer and the like are washed away with ultrapure water, and the cool mode can be used as the measurement mode.
The polymer or its hydrogenated product whose residual amount is to be measured is usually the one after the sixth step, and, for example, when the contents of the hydrocarbon solvent and water are each less than 1% by mass. Any one can be used.

The polymer produced by the production method of the present invention or the hydrogenated product thereof has the characteristics of excellent thermal stability, corrosion resistance and color tone, and thus can be widely used in various applications.
Specific examples of the use of such a polymer or a hydrogenated product thereof include films, gloves, elastic bands, condoms, OA equipment, various rolls for office use, anti-vibration sheets for electric and electronic equipment, anti-vibration. Rubber, shock-absorbing sheet, shock-absorbing film / sheet, housing vibration-damping sheet, molding material used for vibration-damping material, adhesive tape, pressure-sensitive adhesive sheet, pressure-sensitive adhesive label, dust-removing roller, etc. It can be used for applications such as adhesives used for sanitary goods and bookbinding, elastic fibers used for clothing, sports goods and the like.

The polymer produced by the production method of the present invention or a hydrogenated product thereof may be used alone or by adding a polymer component other than the polymer or a hydrogenated product thereof as required to form a film. Good.
When the polymer or the like is formed into a film, the method of forming the polymer or the like into a film is not particularly limited, and a conventionally known film forming method can be applied, but a viewpoint of obtaining a smooth film with good productivity. Therefore, extrusion molding is preferable, and extrusion molding using a T-die is particularly preferable.
As a specific example of extrusion molding using a T-die, a polymer or the like melted within a range of 150 ° C to 250 ° C is extruded from a T-die mounted on a single-screw extruder or a twin-screw extruder, and a take-up roll is used. There is a method of winding while cooling with. The film may be stretched when cooled by a take-up roll. Further, when the film is wound, a film may be formed while coating a melt such as a polymer on a substrate made of polyethylene terephthalate, polyethylene, polypropylene, a nonwoven fabric or release paper, or a melt such as a polymer. May be sandwiched between these base materials to form a film. The film thus obtained may be used in the form of being integrated with the base material or may be peeled off from the base material for use.

It is preferable that the film has excellent uniformity in film thickness.
The fact that the film has excellent uniformity of film thickness means that, for example, a sample film is cut into a length of 30 cm along the melt flow direction at the time of molding, and 2 cm along the melt flow direction is cut at the center of the film. The thickness of the film was measured at 15 points at every interval using a digital thickness gauge (manufactured by Toyo Seiki Co., Ltd., measurement accuracy: 0.001 mm unit), and the film was obtained from these measured values with respect to the average value of the film thickness. It can be confirmed from the fact that the ratio of the standard deviation of thickness (standard deviation / average value) is usually 15% or less, preferably 12% or less, more preferably 9% or less.

It is preferable that the film has excellent stretchability.
The breaking strength of the film is preferably 20 MPa or more, more preferably 22 MPa or more. The elongation at break of the film is preferably 650% or more, more preferably 700%. The permanent elongation of the film is usually 10 or less, preferably 9 or less, more preferably 8 or less.

The breaking strength and breaking elongation of the film can be obtained by preparing a film having a width of 25 mm from the film and using it as a sample, and measuring it along the direction perpendicular to the melt flow during molding.
As a measuring procedure of the breaking strength and the breaking elongation of the film, for example, the sample is fixed to the Tensilon universal testing machine RTC-1210 manufactured by ORITEC in a tension-free distance of 40 mm, and the sample is broken at a speed of 500 mm / min. And the elongation at break and elongation at break can be determined.

Further, the permanent elongation of the film can be obtained, for example, by measuring with a Tensilon universal testing machine RTC-1210 manufactured by ORITEC in accordance with ASTM 412. Specifically, DieA was used as the sample shape, and the stretchable film was stretched at an elongation rate of 100% with the distance between the marked lines before stretching being 40 mm, and the stretched film was held for 10 minutes in that state and then rapidly stretched without rebounding. After being allowed to contract for 10 minutes, the distance between marked lines can be measured, and the permanent elongation can be calculated based on the following formula.
Permanent elongation (%) = (L1-L0) / L0 × 100
L0: Distance between marked lines before extension (mm)
L1: Distance between marked lines after shrinking and leaving for 10 minutes (mm)

  The film may be used as a single layer as it is, or may be laminated with other members to be used as a multilayer body depending on the application. As a specific example of when used as a single layer, a stretchable film used for sanitary products such as disposable diapers and sanitary products, a protective film for protecting optical films, heat used as shrink-wrapping containers and heat-shrinkable labels. The use as a shrinkable film can be mentioned. As a specific example in the case of forming a multilayer body, after slitting the film, a hot-melt adhesive or the like is applied to form a tape, and in a state where the tape is compressed, a non-woven fabric, a woven fabric, a plastic film, or these An example of forming a stretchable gather member by adhering to the laminated body and relaxing the shrinkage of the tape. Further, according to other uses, appropriately processed according to a known method, for example, stretchable base material for stretchable ships, gloves, surgical gloves, finger cots, hemostatic bands, contraceptives, headbands, goggle bands, rubber bands, etc. It can also be used as a member.

The above film can be used by being laminated with other members. For example, after slitting the film, a hot melt adhesive or the like is applied to form a tape, and the tape is adhered to a non-woven fabric, a woven fabric, a plastic film, or a laminate of these tapes in a compressed state. By relaxing the shrinkage, a stretchable gather member can be formed.
Further, according to other uses, appropriately processed according to a known method, for example, stretchable compressible base material, gloves, surgical gloves, finger cots, hemostatic bands, contraceptives, headbands, goggle bands, rubber bands, etc. It can be used as a member.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and has any similar effect to the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, parts and% in each example are based on mass unless otherwise specified.

Various measurements were performed according to the following methods.
[Thermal stability of block copolymer]
The pellet block copolymer obtained was used as a sample, and the rate of change in viscosity before and after heating was taken as the viscosity retention rate%, and the thermal stability was determined from this value. Specifically, the block copolymer was heated in an oven at 140 ° C. for 1 hour, and the viscosity of the polymer before and after heating was measured using a flow tester (CFT-500D) manufactured by Shimadzu Corporation. The measurement conditions are as follows. The measurement was performed after the sample was kept at 200 ° C. for 6 minutes under the conditions of a sample amount of 1.5 g, a die diameter of 1 mm and a load of 100 kg. The change in viscosity of the polymer before and after heating was taken as the viscosity retention rate% and calculated from the following formula. It can be said that the higher the viscosity retention value, the better the thermal stability.
Viscosity retention rate (%) = V1 / V0 × 100
V0: Viscosity before heating (cps)
V1: 140 ° C., viscosity after heating for 1 hour (cps)
Viscosity retention rate is 95% or more ◎
Viscosity retention rate is 90% or more and less than 95% ○
Viscosity retention rate is 80% or more and less than 90% △
Viscosity retention rate is less than 80% ×

[Residual amount of Li atom]
The amount of Li of the obtained block copolymer in a pellet state was measured using ICP-MS (Agilent 7500cs). The measurement procedure is as follows. After dissolving the block copolymer in nitric acid, the polymer was washed off with ultrapure water, and the measurement mode was cool mode. It can be said that the smaller the amount of remaining Li atoms, the better.
30ppm or less ◎
30 ppm or more and less than 40% or less
40 ppm or more and less than 50% or less △
50ppm or less ×

[Film crack test]
A film having a width of 25 mm was prepared, and this film was used as a sample and measured along the direction perpendicular to the melt flow during molding. The measurement procedure is as follows. The sample was fixed to a Tensilon universal testing machine RTC-1210 manufactured by ORIENTEC with a chuck distance of 40 mm without tension. Then, the sample was continuously stretched so that a constant load of 5 N was applied, and the presence or absence of cracks was observed after 3 hours.
No cracking after 3 hours ○
Cracking occurred after 3 hours ×

A film having a width of 25 mm as a sample was manufactured by the following method.
First, 100 parts of the obtained block copolymer pellets and 67 parts of polystyrene (“PSJ433” manufactured by PS Japan Co., Ltd.) were charged into a twin-screw extruder equipped with a T-die.
Then, in this twin-screw extruder, these are heated, melted and kneaded at 200 ° C. to form a block copolymer composition, which is continuously extruded for 20 minutes so as to be sandwiched between PET release films. As a result, a film having an average thickness of 0.05 mm was formed.
The details of the film forming conditions were as follows.

Composition processing speed: 5 kg / hr
Film take-up speed: 4m / min
Extruder temperature: Input port 100 ° C, T-die adjusted to 200 ° C Screw: Full flight Extruder L / D: 30
T-die: width 200mm, lip 0.5mm

[Preparation Example of Polymer Solution]
In a pressure resistant reactor, 9778 kg of cyclohexane, 0.85 mol of N, N, N ', N'-tetramethylethylenediamine (hereinafter, referred to as TMEDA) and 489.6 kg of styrene were added, and the mixture was stirred at 40 ° C. , N-butyllithium (56.8 mol) were added, and the mixture was polymerized for 1 hour while raising the temperature to 50 ° C. The polymerization conversion rate of styrene was 100%.
Subsequently, while controlling the temperature so as to maintain 50 ° C. to 60 ° C., 3575 kg of isoprene was continuously added to the reactor over 1 hour. After the addition of isoprene was completed, the polymerization was continued for another hour. The polymerization conversion rate of isoprene was 100%.
Then, 489.6 kg of styrene was continuously added over 1 hour while continuously controlling the temperature so as to maintain 50 to 60 ° C. After the addition of styrene was completed, the polymerization was further performed for 1 hour to form a styrene-isoprene-styrene triblock copolymer having active terminals. The polymerization conversion rate of styrene was 100%. Then, 40.3 mol of methanol as a polymerization terminator was added and mixed to deactivate some active ends of the styrene-isoprene-styrene triblock copolymer having active ends to block the reaction. A styrene-isoprene-styrene triblock copolymer to be the copolymer B was formed.
Thereafter, 945.9 kg of styrene was continuously added over 1 hour while further controlling the temperature so as to maintain 50 ° C to 60 ° C. After the addition of styrene was completed, the polymerization was further performed for 1 hour to form a styrene-isoprene-styrene triblock copolymer having an active terminal, which was the block copolymer A. The polymerization conversion rate of styrene was 100%.
In this way, a cyclohexane solution (polymer solution) of a block copolymer (block copolymer mixture) containing the block copolymer A having an active end and the block copolymer B was prepared.

[Example 1]
A cyclohexane solution of a block copolymer (polymer solution) containing a block copolymer A having an active end and a block copolymer B prepared by the above-mentioned preparation example of the polymer solution was used as a decatalyzing agent. Malic acid and water as a reaction terminator were added 0.4 times mol and 40 times mol, respectively, with respect to the metal amount (lithium) of the catalyst (organic lithium compound) used for the polymerization, and mixed sufficiently to stop the reaction. (First step).
Next, 0.1 part of 2,6-di-tert-butyl-p-cresol as a stabilizer is used per 100 parts of the block copolymer, and tris (2,4) which is a non-hydrolyzable phosphorus antioxidant. 0.3 part of -di-tert-butylphenyl) phosphite was added (second step).
Then, the block copolymer was separated from the block copolymer solution as a hydrous crumb by steam stripping (third step).
Then, the block copolymer separated as an aquatic slurry hydrous crumb was dehydrated by a vibrating screen, centrifugal dehydration or the like (fourth step).
Next, 0.004 parts of Demol EP (manufactured by Kao Corporation) was added as a nonionic surfactant to the hydrous crumb after dehydration (fifth step).
Then, the water-containing crumb was dried by extrusion using a twin-screw extruder dryer to obtain a block copolymer (sixth step). The block copolymer obtained in a strand form from the tip of the extruder was pelletized with a pelletizer.

  The pellets of the obtained block copolymer were used to evaluate the thermal stability of the block copolymer, the residual amount of Li atoms and the cracking of the film.

[Examples 2 to 7 and Comparative Examples 1 to 5]
Pellets of the block copolymer were produced and evaluated in the same manner as in Example 1 except that the types and amounts of the components to be added were changed as shown in Table 1 and Table 2.
The results of this are shown in Tables 1 and 2 below.
The adipic acid and sebacic acid added as polyvalent organic acids have a solubility in water of 100 g / L or less.
The amount of water added was as shown in Tables 1 and 2 below, and the amount of organic acid added was the same as in Example 1.

  From Tables 1 and 2, the polymers obtained by the production methods of Examples 1 to 7 are superior in thermal stability to the polymers obtained by the production methods of Comparative Examples 1 to 5. It was confirmed that the following results were obtained, that the amount of residual lithium was small and the color tone was excellent, and that the film had few cracks and was excellent in corrosion resistance.

Claims (10)

A polymer solution obtained by polymerizing a conjugated diene monomer and / or an aromatic vinyl monomer with an organolithium compound as an initiator in a hydrocarbon solvent, or a polymer solution containing a hydrogenated product thereof, is treated with water and water. A first step of adding a polyvalent organic acid having a solubility in 100 g / L or more,
In the polymer solution after the first step, the phenol antioxidant is in the range of 0.005 parts by mass to 5 parts by mass with respect to 100 parts by mass of the polymer or its hydrogenated product, and the phosphorus antioxidant. In a range of 0.005 parts by mass to 5 parts by mass, and
A third step of removing the hydrocarbon solvent from the polymer solution after the second step by steam stripping to form a hydrous crumb;
A fourth step of dehydrating the hydrous crumb after the third step,
At least one timing before the second step, after the second step, before the third step, and after the fourth step, with respect to 100 parts by mass of the polymer or its hydrogenated product, a nonionic surfactant. In a range of 0.0001 parts by mass to 0.005 parts by mass, and
A sixth step of further drying the hydrous crumb after the fourth step,
It has a, the execution timing of the fifth step, the polymer production process of which is a timing after at least the fourth step.   The method for producing a polymer according to claim 1, wherein the conjugated diene monomer is at least one of butadiene and isoprene.   The method for producing a polymer according to claim 1 or 2, wherein the aromatic vinyl monomer is styrene. The polymer or a hydrogenated product thereof is a block copolymer mixture containing a block copolymer A represented by the following formula (A) and a block copolymer B represented by the following formula (B), or a hydrogenated product thereof. It is a thing, The manufacturing method of the polymer in any one of Claim 1 to Claim 3 characterized by the above-mentioned.
^{Ar1 a -D a -Ar2 a (A} )
_{^{(Ar b -D b) n X}} (B)
(Wherein, the Ar @ 1 ^a and Ar ^b, respectively the weight average molecular weight of an aromatic vinyl polymer block in the range of 6,000-20,000, Ar @ 2 ^a has a weight average molecular weight of 30,000～400, represents an aromatic vinyl polymer block in the range of 000, D ^a is a vinyl bond content represents a conjugated diene polymer block in the range of 1 mol% to 20 mol%, D ^b is a vinyl bond content Represents a conjugated diene block having a weight average molecular weight in the range of 20,000 to 200,000 in the range of 1 mol% to 20 mol%, X represents a single bond or a residue of a coupling agent, and n is 2 It is the above integer.)   The method for producing a polymer according to any one of claims 1 to 4, wherein the polyvalent organic acid is a hydroxycarboxylic acid.   The method for producing a polymer according to claim 5, wherein the hydroxycarboxylic acid is an aliphatic hydroxycarboxylic acid.   The method for producing a polymer according to claim 6, wherein the aliphatic hydroxycarboxylic acid is at least one selected from the group consisting of malic acid, citric acid and tartaric acid.   The phosphorus-based antioxidant is tris (2,5-di-tert-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris [2,4-bis (1, 1-dimethylpropyl) phenyl] phosphite, tris (mono- or di-tert-butylphenyl) phosphite, 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecylphosphite ), Cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenylphosphite), and tris (nonylphenyl) phosphite. The method for producing a polymer according to any one of claims 1 to 7, which is characterized.   The nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene ether, polyoxyethylene alkyl ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene sorbitan. 9. At least one selected from the group consisting of fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, alkylalkanolamide, and polyoxyethylene fatty acid ester, any one of claims 1 to 8. A method for producing the polymer according to any one of the claims. The addition amount of the water is in the range of 0.05 times to 1000 times mol with respect to the total amount of lithium atoms constituting the organolithium compound, and the addition amount of the polyvalent organic acid constitutes the organolithium compound. The production of the polymer according to any one of claims 1 to 9, which is in a range of 0.15 times to 0.5 times the molar amount of the total lithium atoms. Method.