JP2013209471A - Method for producing diene rubber and method for producing polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing various polymers such as diene rubber with a low gel content.SOLUTION: In a method for producing diene rubber by polymerizing a conjugated diene-based monomer by adding water, a transition metal catalyst and an organometallic promoter to a monomer liquid containing the conjugated diene-based monomer and an organic solvent, an antigelling agent is added in an amount of 1-100 mmol per cubic meter of the monomer liquid. Also in a method for producing a polymer by adding water and an organometallic compound to a monomer liquid containing a monomer and an organic solvent to polymerize the monomer, an antigelling agent is added in an amount of 1-100 mmol per cubic meter of the monomer liquid.

Description

  The present invention relates to a method for producing various polymers such as diene rubbers.

  In the molecular chain of a diene rubber such as polybutadiene, a so-called microstructure is formed by a bond portion (1,4-structure) formed by polymerization at the 1,4-position and by polymerization at the 1,2-position. Together with the bonded portion (1,2-structure). The 1,4-structure is further divided into two types, a cis structure and a trans structure. On the other hand, the 1,2-structure is a structure having a vinyl group as a side chain. It is known that polybutadienes having different microstructures can be produced depending on the kind of the polymerization catalyst, and they are used in various applications depending on their properties.

  That is, many proposals have been made on polymerization catalysts for conjugated diene monomers such as 1,3-butadiene. In particular, high cis-1,4-polybutadiene rubber, that is, polybutadiene rubber having a high content of cis-1,4 bonds has excellent thermal and mechanical properties. Many polymerization catalysts for cis-1,4 polymerization have been developed.

  For example, in Patent Document 1, 1,3-butadiene is polymerized in a solvent containing 20% or more of benzene by a catalyst comprising a mixture obtained by thoroughly mixing and aging a hydrocarbyl aluminum compound and water and cobalt dioctate. A method for producing high cis-1,4-polybutadiene is disclosed. Patent Document 2 discloses a method for producing high cis-1,4-polybutadiene in which 1,3-butadiene is polymerized using a catalyst comprising a cobalt compound, an acidic metal halide, an alkylaluminum compound, and water. . Patent Document 3 discloses a method of polymerizing 1,3-butadiene in a solvent composed of a linear or branched aliphatic hydrocarbon using a catalyst composed of diethylaluminum chloride, water, and cobalt octoate. Has been.

  In these methods, in order to increase the catalytic activity, it is essential to contain water in the solvent. For example, when the organoaluminum compound and water are mixed non-uniformly, cationic species are generated and 1 In the polymerization of 1,3-butadiene, the resulting polymer contains a double bond, which makes it easy to form a gel. A large amount of gel is contained in the polybutadiene, or the gel adheres to the stirring blade and the inner wall in the polymerization tank. In some cases, the polymerization reaction could not be continued for a long time.

  Therefore, in Patent Document 4, the moisture concentration of an inert organic solvent solution of 1,3-butadiene is adjusted, a halogen-containing organoaluminum compound is added to the resulting solution and aged for a predetermined time, and then a cobalt compound is added. Thus, a method of suppressing the generation of gel by polymerizing is disclosed. Patent Document 5 discloses a method in which a necessary amount of water is dispersed in a porous filter medium having a pore size of 5 μm or less to suppress gel generation and prevent scale adhesion.

  Furthermore, by devising a method for adding water, a method for producing polybutadiene having no gel adhesion to the polymerization apparatus and having a low gel content has been studied. Patent Document 6 discloses a method in which necessary water is added to an inert solvent or an inert organic solvent solution of 1,3-butadiene in a steam and / or hot water state and mixed. Patent Document 7 discloses a method in which water treated with tourmaline is added to an inert solvent or an inert organic solvent solution of 1,3-butadiene as necessary moisture and mixed. Patent Document 8 discloses a method of aging by adding water and organoaluminum in an inert solvent or an inert organic solvent solution of 1,3-butadiene in the presence of hydrogen.

  Patent Document 9 describes a method for producing polybutadiene using a metallocene complex of a vanadium metal compound, an ionic compound of a non-coordinating anion and a cation, and / or a polymerization catalyst comprising an aluminoxane. This polybutadiene has a microstructure with a large cis structure and a moderate 1,2-structure and a small trans structure.

Canadian Patent No. 794860 Japanese Patent Publication No.38-1243 Japanese Patent Publication No. 61-54808 JP 58-101105 A Japanese Patent Laid-Open No. 4-85304 Japanese Patent Laid-Open No. 2002-20427 Japanese Patent Laid-Open No. 2002-60410 JP 2003-12715 A JP-A-9-291108

  However, when a diene rubber having a low gel content is produced by a method as described in the above-mentioned literature, the yield of the diene rubber obtained is small and the production efficiency is low, which causes high costs. Such a problem similarly occurs in a method for producing a polymer having a step of adding water and an organometallic compound.

  Therefore, an object of the present invention is to provide a method for efficiently producing various polymers such as a diene rubber having a low gel content.

The present invention is a method for producing a diene rubber in which water, a transition metal catalyst, and an organic metal promoter are added to a monomer liquid containing a conjugated diene monomer and an organic solvent, and the conjugated diene monomer is polymerized. ,
The present invention relates to a method for producing a diene rubber having a step of adding 1 to 100 mmol of an antigelling agent to 1 m ^{3 of the} monomer liquid.

The present invention is a method for producing a polymer in which water and an organometallic compound are added to a monomer liquid containing a monomer and an organic solvent, and the monomer is polymerized.
The present invention relates to a method for producing a polymer having a step of adding 1 to 100 mmol of an antigelling agent to 1 m ^{3 of the} monomer liquid.

  According to the present invention, it is possible to provide a method for efficiently producing various polymers such as a diene rubber having a low gel content.

  In the present invention, a transition metal catalyst and an organometallic promoter are added to a monomer liquid containing a conjugated diene monomer and water, thereby polymerizing the conjugated diene monomer to produce a diene rubber having a low gel content. To do.

<Monomer solution>
The monomer liquid used in the present invention contains a conjugated diene monomer that gives a target diene rubber and an organic solvent. The monomer liquid may contain a copolymerization monomer other than the conjugated diene monomer as a monomer that gives the target diene rubber.

  Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2- Methyl-1,3-pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene Can be mentioned. Of these, 1,3-butadiene is preferred. As the conjugated diene monomer, one kind may be used alone, or two or more kinds may be used in combination.

  Examples of the copolymerization monomer other than the conjugated diene monomer include aromatic vinyl compounds such as styrene and α-methylstyrene. Another monomer may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the organic solvent include aromatic hydrocarbons such as toluene, benzene and xylene; aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane and n-heptane; cyclopentane, cyclohexane and the like Olefinic hydrocarbons such as 1-butene, cis-2-butene and trans-2-butene; halogenated hydrocarbons such as methylene chloride; and other petroleum such as mineral spirits, solvent naphtha and kerosene And system solvents. Of these, cyclohexane is preferable. An organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The concentration of the conjugated diene monomer in the monomer liquid is preferably in the range of 10 to 90% by weight, more preferably in the range of 20 to 70% by weight, and still more preferably in the range of 25 to 50% by weight.

<Water>
In the present invention, water is allowed to coexist when the conjugated diene monomer is polymerized. The amount of water added to the monomer liquid is preferably in the range of 0.5 to 5 mol, more preferably in the range of 1 to ³ mol, with respect to 1 m ³ of the monomer liquid.

<Transition metal catalyst>
In the present invention, a transition metal catalyst is used as a catalyst for polymerizing a conjugated diene monomer. Since the transition metal catalyst greatly affects the physical properties of the diene rubber obtained by polymerizing the conjugated diene monomer, the transition metal catalyst may be appropriately selected in consideration of the physical properties of the target diene rubber.

  Examples of transition metal catalysts include cobalt-based catalysts, nickel-based catalysts, neodymium-based catalysts, vanadium-based catalysts, and titanium-based catalysts. Among these, a cobalt catalyst or a nickel catalyst is preferable, and a cobalt catalyst is more preferable. A transition metal catalyst may be used individually by 1 type, and may be used in combination of 2 or more type.

  Cobalt catalysts include cobalt halide salts such as cobalt chloride and cobalt bromide; inorganic acid cobalt salts such as cobalt sulfate and cobalt nitrate; cobalt octaate, cobalt octylate, cobalt naphthenate, cobalt acetate, cobalt malonate, etc. And cobalt complexes such as bisacetylacetonate cobalt, trisacetylacetonate cobalt, acetoacetic acid ethyl ester cobalt, cobalt salt pyridine complex, cobalt salt picoline complex, and cobalt salt ethyl alcohol complex. Of these, cobalt octaate is preferable.

  Examples of the nickel-based catalyst include a catalyst composed of a nickel compound-organoaluminum compound. Nickel compounds include: nickel naphthenate, nickel formate, nickel octylate, nickel stearate, nickel citrate, nickel benzoate, nickel toluate, etc .; organic complexes such as nickel acetylacetonate; alkylbenzene sulfonic acid Examples thereof include nickel and nickel oxyborate. Of these, nickel octylate is preferable.

  The amount of the transition metal catalyst to be used can be appropriately set in consideration of the Mooney viscosity, linearity, etc. of the target diene rubber. For example, when increasing the Mooney viscosity or linearity of the diene rubber, the amount of the conjugated diene monomer added to 1 mmol of the transition metal catalyst is preferably in the range of 400 to 4000 mol, more preferably in the range of 500 to 2000 mol. Preferably, the range is 600 to 1500 mol, more preferably 700 to 1000 mol. Moreover, when making Mooney viscosity and linearity of diene rubber low, it is preferable to make the addition amount of the conjugated diene monomer with respect to 1 mmol of transition metal catalysts into the range of 100-1400 mol, and it is more preferable to set it as the range of 200-1000 mol. Preferably, the range is 300 to 850 mol, more preferably 350 to 750 mol.

<Organic metal promoter>
In the present invention, an organic metal promoter is used together with a transition metal catalyst. As the organometallic promoter, for example, an organoaluminum compound can be used. One organometallic promoter may be used alone, or two or more organometallic promoters may be used in combination.

  The organoaluminum compound may be a non-halogenated organometallic compound or a halogenated organometallic compound, but it is preferable to use at least a halogenated organometallic compound. Non-halogenated organoaluminum compounds include trialkylaluminum; organoaluminum hydrides such as dialkylaluminum hydride and alkylaluminum sesquihydride. Examples of the halogenated organic aluminum include dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum dichloride, alkylaluminum dibromide, alkylaluminum sesquichloride, and alkylaluminum sesquibromide.

  Specific examples of organoaluminum compounds include trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum chloride, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum. Examples include hydride, diisobutylaluminum hydride, and ethylaluminum sesquihydride. As the non-halogenated organoaluminum compound, trialkylaluminum is preferable, and triethylaluminum is more preferable. As the halogenated organoaluminum compound, organoaluminum chloride is preferred, and diethylaluminum chloride is more preferred.

  It is also preferable to use a combination of a non-halogenated organometallic compound and a halogenated organometallic compound as the organometallic promoter. In this case, the amount of the halogenated organometallic compound is preferably in the range of 0.1 to 99 mol, more preferably in the range of 0.25 to 19 mol, with respect to 1 mol of the non-halogenated organometallic compound. More preferably, the range is from 0 to 15 mol, and particularly preferably from 3 to 9 mol.

  The amount of the organometallic promoter used is preferably in the range of 50 to 2000 mol, more preferably in the range of 100 to 1000 mol, and still more preferably in the range of 200 to 500 mol with respect to 1 mol of the transition metal catalyst.

  This organometallic cocatalyst develops a function as a cocatalyst by reacting with water added to the monomer liquid, but when the organometallic cocatalyst and water are mixed non-uniformly, a gel is likely to be formed. Therefore, the relationship with the amount of water is important. That is, the gel is easily generated regardless of whether the amount of the organometallic promoter added to the water is large or small. Furthermore, when the amount of the organometallic promoter added to water is large, the yield of the resulting diene rubber tends to decrease. The addition of a gel inhibitor to the monomer solution tends to reduce the yield of the resulting diene rubber, so it is important to improve the yield of the diene rubber.

  Therefore, in the present invention, the amount of the organometallic promoter added per 1 mol of water is preferably in the range of 0.5 to 2.5 mol. Thus, by relatively increasing the amount of the organometallic promoter relative to water, a diene rubber having a low gel content can be more efficiently produced. The addition amount of the organometallic promoter relative to 1 mol of water is more preferably in the range of 0.8 to 2.0 mol, and further preferably in the range of 1.0 to 1.8 mol.

<Molecular weight regulator>
In the present invention, a molecular weight modifier can be used in producing a diene rubber by polymerizing a conjugated diene monomer.

  Examples of molecular weight regulators include cyclooctadiene, allene, methylallene (1,2-butadiene), dicyclopentadiene, 5-ethylidene-2-norbornene, 1,5-hexadiene and the like; ethylene, propylene, 1 Examples include acyclic monoolefins such as -butene, 2-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene, and cyclic monoolefins such as cyclopentene, cyclohexene and norbornene. Of these, cyclooctadiene is preferable. A molecular weight regulator may be used individually by 1 type, and may be used in combination of 2 or more type.

Regarding the amount of the molecular weight modifier to be used, the addition amount of the molecular weight modifier to the monomer liquid 1 m ³ is preferably in the range of 1 to 50 mol, more preferably in the range of 3 to 30 mol, and in the range of 5 to 20 mol. More preferably.

<Anti-gelling agent>
In the present invention, an antigelling agent is used in producing a diene rubber by polymerizing a conjugated diene monomer. Examples of the gelation inhibitor include phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, and nitro compound antioxidants. Of these, phenol-based antioxidants, amine-based antioxidants or sulfur-based antioxidants are preferable, and sulfur-based antioxidants are more preferable. One antigelling agent may be used alone, or two or more antigelling agents may be used in combination.

  Examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol, derivatives of 6-tert-butyl-3-methylphenol, 2,6-di-tert-butyl-4-n- Butylphenol, 4-hydroxymethyl-2,6-di-tert-butylphenol, 2-methyl-4,6-dinonylphenol, 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 2,2 -Methylenebis (4-methyl-6-cyclohexylphenol), 4,4'-methylenebis (2,6-di-tert-butylphenol), 2,2'-methylenebis (6-α-methylbenzyl-p-cresol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,2′-dihydroxy-3,3′-di ( α-methylcyclohexyl) -5,5′-dimethyldiphenylmethane.

  Examples of amine-based antioxidants include N- (3-methacryloyloxy-2-hydroxypropyl) -N′-phenyl-p-phenylenediamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, aldol-α-naphthylamine, Reaction product of phenyl-β-naphthylamine and acetone, p-isopropoxydiphenylamine, p- (p-toluenesulfonylamide) -diphenylamine, reaction product of diphenylamine and acetone, reaction product of diphenylamine and diisobutylene, N , N′-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, N, N′-bis (1,4- Dimethylpentyl) -p-pheny Diamine, 2,2,4-trimethyl-1,2-dihydroquinone polymer, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl -1,2-dihydroquinoline.

  Sulfuric antioxidants include thiodipropionic acid, dilauryl thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl thiodipropionate, distearyl-β, β'-thio Dibutyrate, thiobis (β-naphthol), thiobis (N-phenyl-β-naphthylamine, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, dodecyl mercaptan, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel diptyl Examples thereof include dithiocarbamate and nickel isopropyl xanthate, among which dilaurylthiodipropionate is preferable.

  Regarding the amount of the antigelling agent used, if the addition amount of the antigelling agent is small, the gel content of the resulting diene rubber will be high. On the other hand, from the viewpoint of lowering the gel content of the resulting diene rubber, the addition amount of the anti-gelling agent may be large, but in this case, the yield of the obtained diene rubber is reduced.

Therefore, in the present invention, the amount of anti-gelling agent to monomer solution 1 m ³ in the range of 1 to 100 mmol. Thus, the diene rubber with a low gel content can be efficiently manufactured by adjusting the amount of the gelation inhibitor with respect to the monomer. The amount of the gelation inhibitor added to the monomer liquid 1 m ³ is preferably in the range of 3 to 70 mmol, and more preferably in the range of 5 to 50 mmol.

<Polymerization of conjugated diene monomer>
In the present invention, the conjugated diene monomer in the monomer liquid is polymerized by adding water, a transition metal catalyst, an organometallic promoter, and an antigelling agent (preferably, a molecular weight modifier) to the monomer liquid. To obtain a diene rubber.

The order of adding each component may be appropriately selected in consideration of the physical properties of the target diene rubber, but it is preferable to add a transition metal catalyst for initiating the polymerization reaction last. Specifically, as the addition order of each component,
(1) Water → Anti-gelling agent → Organometallic promoter → Transition metal catalyst (2) Water → Organometallic promoter → Gelling inhibitor → Transition metal catalyst (3) Antigelling agent → Water → Organometallic promoter → Transition metal catalyst (4) Antigelling agent → Organometallic promoter → Water → Transition metal catalyst (5) Organometallic promoter → Water → Antigelation agent → Transition metal catalyst (6) Organometallic promoter → Gelation Inhibitors → water → transition metal catalysts. The molecular weight modifier can be added, for example, at an arbitrary timing before adding the transition metal catalyst, but it is preferable to add it at the same time as the anti-gelling agent or immediately before or after the anti-gelling agent. Moreover, it is preferable to age | cure the liquid after adding an organometallic promoter before adding a transition metal catalyst.

  The monomer liquid may contain the entire amount of the conjugated diene monomer or may contain only a part of the conjugated diene monomer. When the monomer liquid contains only a part of the conjugated diene monomer, the remaining conjugated diene monomer may be added at any timing before the addition of the transition metal catalyst, or after the addition of the transition metal catalyst (that is, the start of polymerization). It may be added later).

  The polymerization temperature is preferably in the range of -30 to 100 ° C, more preferably in the range of 30 to 80 ° C. The polymerization time is preferably in the range of 5 minutes to 12 hours, and more preferably in the range of 10 minutes to 6 hours. The polymerization pressure is preferably in the range of normal pressure (0 atm) to 10 atm [gauge pressure].

<Stop of polymerization of conjugated diene monomer>
In the present invention, the polymerization of the conjugated diene monomer can be stopped by adding a polymerization terminator after the polymerization of the conjugated diene monomer under predetermined conditions.

  Examples of the polymerization terminator include water, alcohol, organic acid, inorganic acid, and phenol. Among these, water, alcohol, or phenol is preferable, and a combination of water or alcohol and phenol is also preferable. A polymerization terminator may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the alcohol, an alcohol having 5 or less carbon atoms is preferable, and specifically, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, or pentanol is preferable. Of these, ethanol is preferred.

  Examples of phenol include 2,6-di-tert-butyl-4-methylphenol, derivatives of 6-tert-butyl-3-methylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 4- Hydroxymethyl-2,6-di-tert-butylphenol, 2-methyl-4,6-dinonylphenol, 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 2,2-methylenebis (4 -Methyl-6-cyclohexylphenol), 4,4'-methylenebis (2,6-di-tert-butylphenol), 2,2'-methylenebis (6-α-methylbenzyl-p-cresol), 4,4 ' -Butylidenebis (3-methyl-6-tert-butylphenol), 2,2'-dihydroxy-3,3'-di (α-methylsilane) Rohexyl) -5,5′-dimethyldiphenylmethane, 4,6-bis (octylmethyl) -o-cresol, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. Among them, 2,6-di-tert-butyl-4-methylphenol or 4,6-bis (octylmethyl) -o-cresol is preferable, and 2,6-di-tert-butyl-4-methylphenol is more preferable. .

<Diene rubber>
The diene rubber produced by the method of the present invention is determined by the conjugated diene monomer used and the polymerization reaction. For example, 1,4-butadiene is obtained by performing cis-1,4 polymerization using 1,3-butadiene as the conjugated diene monomer.

  The weight average molecular weight (Mw) of the diene rubber produced by the method of the present invention is preferably in the range of 50,000 to 3000000, more preferably in the range of 100,000 to 150,000, and still more preferably in the range of 200000 to 1000000. The molecular weight distribution (Mw / Mn) of the diene rubber produced by the method of the present invention is preferably in the range of 1.5 to 9.0, more preferably in the range of 2.0 to 5.0, and 2.2 to A range of 4.0 is more preferred. When the value of the molecular weight distribution is small, the workability tends to be lowered, and when the molecular weight distribution is large, the fracture characteristics tend to be lowered. In addition, the measuring method of Mw and Mw / Mn is demonstrated in detail in the Example mentioned later.

  The diene rubber produced by the method of the present invention preferably has a high cis-1,4 structure. Specifically, the ratio of the cis-1,4 structure of the diene rubber is preferably in the range of 80.0 to 100%, more preferably in the range of 88.0 to 99.8%, and 94.0 to 99.99. A range of 0% is more preferable, and a range of 96.0 to 98.9% is particularly preferable. In addition, the measuring method of the ratio of cis-1,4 structure is demonstrated in detail in the Example mentioned later.

  The gel content (ratio of toluene insoluble matter) of the diene rubber produced by the method of the present invention is preferably 0.1% by weight or less, more preferably 0.07% by weight or less, 0.04% by weight or less is more preferable, and 0.02% by weight or less is particularly preferable. When the gel content exceeds 0.1% by weight, for example, when used as a resin film modifier, the problem of fish eyes tends to occur. The gel content may be low, but is usually 0.001% by weight or more. In addition, the measuring method of gel content rate is demonstrated in detail in the Example mentioned later.

The 5 wt% toluene solution viscosity (T _cp ) of the diene rubber produced by the method of the present invention is preferably in the range of 10 to 300 cps, more preferably in the range of 15 to 200 cps, and still more preferably in the range of 20 to 180 cps. A range of 25 to 160 cps is particularly preferred. In addition, the measuring method of _Tcp is _demonstrated in detail in the Example mentioned later.

The Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of the diene rubber produced by the method of the present invention is preferably in the range of 10 to 200, more preferably in the range of 20 to 100, still more preferably in the range of 25 to 80, 27 A range of ˜60 is particularly preferred. In addition, the measuring method of ML _{1 + 4} will be described in detail in Examples described later.

T _cp / ML _{1 + 4} of the diene rubber produced by the method of the present invention is preferably in the range of 0.5 to 3.5, more preferably in the range of 0.7 to 3.3, and 0.9 to 3. A range of 0 is more preferred. Here, T _cp / ML _{1 + 4} is an index of linearity (branch degree of rubber molecules). That is, the lower the T _cp / ML _{1 + 4} , the lower the linearity of the rubber and the more highly branched polymer structure. Further, the higher T _cp / ML _{1 + 4} is, the higher the linearity of the rubber is, and it has a low branching polymer structure.

  The diene rubber produced by the method of the present invention can be used for impact resistance modification of a polymer based on a vinyl aromatic compound (for example, polystyrene or an ABS polymer produced by a bulk method). The diene rubber produced by the method of the present invention can also be used for producing, for example, tires, hoses, footwear members, industrial belts, medical rubbers, sports equipment, crawlers or packings.

  The method of the present invention can be applied not only to the production method of diene rubber but also to production methods of various polymers. That is, in the method for producing a polymer having a step of adding water and an organometallic compound to a monomer liquid containing a monomer and an organic solvent, a problem of gel generation occurs as in the above-described method for producing a diene rubber.

Even in that case, the gel generation problem can be solved by adding 1 to 100 mmol of the antigelling agent to 1 m ^{3 of} the monomer liquid. The organometallic compound corresponds to the organometallic promoter in the above-described diene rubber production method, and other embodiments are the same as those in the above-described diene rubber production method.

  Hereinafter, the present invention will be specifically described based on examples.

<Example 1>
Monomer liquid 1 dehydrated in advance using molecular sieves in a stainless steel reaction tank (tank volume: 1.5 L, tank diameter: 0.106 m, stirring blade diameter: 0.070 m) substituted with nitrogen gas 0 L (1,3-butadiene: 31.6 wt%, C4 fraction: 37.4 wt%, cyclohexane: 29.5 wt%) was added. While stirring the monomer solution at 400 rpm, 1.7 mmol of water, 4.0 mmol of cyclooctadiene as a molecular weight modifier, and 9.0 μmol of dilauryl thiodipropionate as an antigelling agent were added in this order, Stir at 30 ° C. for 30 minutes. Further, 3.0 mmol of diethylaluminum chloride as a cocatalyst was added and stirred at 25 ° C. for 5 minutes. Then, the temperature of the monomer liquid was raised to 60 ° C., and cis-1,4 polymerization was performed by adding 7.5 μmol of cobalt octoate as a catalyst. After performing polymerization at 60 ° C. for 20 minutes, methanol containing 2,6-di-tert-butyl-p-cresol is added to stop the polymerization, and unreacted butadiene and C4 fraction are removed by evaporation. 129 g of 1,4-polybutadiene rubber was obtained.

Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), ratio of cis-1,4 structure, gel content, 5 wt% toluene solution viscosity (T _cp ) of the obtained 1,4-polybutadiene rubber, and Mooney viscosity (ML _{1 + 4} ) was measured by the following method, and T _cp / ML _{1 + 4} was calculated. These results are shown in Table 1.

(Weight average molecular weight and molecular weight distribution)
The weight average molecular weight and molecular weight distribution of the obtained 1,4-polybutadiene rubber are GPC devices (manufactured by Tosoh Corporation, manufactured by connecting two columns (made by Showa Denko, trade name: Shodex GPC KF-805L column)) in series. (Trade name: HLC-8220 GPC), and calculated based on the examination line of standard polystyrene prepared in advance. THF was used as the eluent, and the column temperature was set to 40 ° C.

(Ratio of cis-1,4 structure)
The proportion of the cis-1,4 structure of the obtained 1,4-polybutadiene rubber was determined by performing infrared absorption spectrum analysis using a 0.4% by weight carbon disulfide solution, 740 cm ⁻¹ (cis), 967 cm ^{−. It} calculated from the absorption intensity ratio of ¹ (trans) and 910 cm ⁻¹ (vinyl).

(Gel content)
The gel content of the obtained 1,4-polybutadiene rubber was calculated as follows. First, 10 g of rubber and 400 mL of toluene were placed in an Erlenmeyer flask and completely dissolved at room temperature (25 ° C.). Then, it filtered using the filter which installed the 200 mesh metal-mesh, the gel adhering to the metal mesh after filtration was vacuum-dried, and the weight was measured by making it into a toluene insoluble content. And the ratio of the toluene insoluble content with respect to the sample rubber was calculated.

(Viscosity of 5 wt% toluene solution)
The 5 wt% toluene solution viscosity (T _cp ) of the obtained 1,4-polybutadiene rubber was determined by dissolving 2.28 g of 1,4-polybutadiene rubber in 50 mL of toluene, 400 was measured at 25 ° C. As the standard solution, a viscometer calibration standard solution (JIS-Z8809) was used.

(Mooney viscosity)
The Mooney viscosity (ML _{1 + 4} ) of the obtained 1,4-polybutadiene rubber was measured at 100 ° C. according to JIS-K6300.

<Example 2, Comparative Example 1>
By adjusting the amount of dilauryl thiodipropionate added, the amount of the gelation inhibitor added to the monomer liquid 1 m ³ was changed as shown in Table 1 in the same manner as in Example 1, 4-polybutadiene rubber was produced. Then, Mw, Mw / Mn, cis-1,4 structure ratio, gel content, T _cp , and ML _{1 + 4} of the obtained 1,4-polybutadiene rubber were measured by the same method as in Example 1, and T _cp / ML _{1 + 4} was calculated. These results are shown in Table 1.

<Comparative example 2>
1,4-polybutadiene rubber was produced in the same manner as in Example 1 except that dilauryl thiodipropionate was not added. Then, Mw, Mw / Mn, cis-1,4 structure ratio, gel content, T _cp , and ML _{1 + 4} of the obtained 1,4-polybutadiene rubber were measured by the same method as in Example 1, and T _cp / ML _{1 + 4} was calculated. These results are shown in Table 1.

  As described above, it can be seen that the method for producing a diene rubber according to the present invention can efficiently produce 1,4-polybutadiene rubber having a low gel content.

Claims (9)

A method for producing a diene rubber in which water, a transition metal catalyst, and an organic metal promoter are added to a monomer liquid containing a conjugated diene monomer and an organic solvent, and the conjugated diene monomer is polymerized.
A method for producing a diene rubber comprising a step of adding 1 to 100 mmol of an anti-gelling agent to 1 m ^{3 of the} monomer liquid.   The method for producing a diene rubber according to claim 1, wherein the amount of the organometallic promoter added to 1 mol of water is 0.5 to 2.5 mol.   The method for producing a diene rubber according to claim 1 or 2, wherein the gelation inhibitor is a sulfur-based antioxidant.   The method for producing a diene rubber according to any one of claims 1 to 3, wherein the organometallic promoter is an organoaluminum compound.   The method for producing a diene rubber according to any one of claims 1 to 4, wherein the conjugated diene monomer is 1,3-butadiene and the diene rubber is 1,4-polybutadiene rubber. A method for producing a polymer in which water and an organometallic compound are added to a monomer liquid containing a monomer and an organic solvent to polymerize the monomer,
A method for producing a polymer comprising a step of adding 1 to 100 mmol of an antigelling agent to 1 m ^{3 of the} monomer liquid.   The method for producing a polymer according to claim 6, wherein the amount of the organometallic promoter added to 1 mol of water is 0.5 to 2.5 mol.   The method for producing a polymer according to claim 6 or 7, wherein the gelation inhibitor is a sulfur-based antioxidant.   The method for producing a polymer according to any one of claims 6 to 8, wherein the organometallic promoter is an organoaluminum compound.