JP5682765B2 - Method for producing diene rubber - Google Patents

Description

  The present invention relates to a method for producing a diene rubber.

  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

  Here, diene rubber with low Mooney viscosity is excellent in processability, productivity, and extrudability, and can be highly filled as a reinforcing agent. Therefore, its application to impact-resistant polystyrene resins and tires has been studied. Yes.

  However, when trying to produce a diene rubber having a low Mooney viscosity by the method 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. .

  Therefore, an object of the present invention is to provide a method for efficiently producing a diene rubber having a low Mooney viscosity.

The present invention relates to a diene rubber having a 5% by weight toluene solution viscosity (T _cp [cps]) of 39.0 or less and a Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of 35 or less measured based on JIS-K6300. A manufacturing method of
A step of polymerizing the conjugated diene monomer by adding water, a transition metal catalyst, an organic metal promoter and a molecular weight regulator to a monomer liquid containing a conjugated diene monomer and an organic solvent;
The amount of the conjugated diene monomer added to 1 mmol of the transition metal catalyst is 100 to 750 mol,
The present invention relates to a method for producing a diene rubber in which the amount of the molecular weight modifier added to the monomer liquid 1 m ³ is 15 to 50 mol.

  The present invention can provide a method for efficiently producing a diene rubber having a low Mooney viscosity.

  In the present invention, a conjugated diene monomer is polymerized by adding water, a transition metal catalyst, an organometallic promoter, and a molecular weight modifier to a monomer liquid containing a conjugated diene monomer and an organic solvent, thereby increasing the Mooney viscosity. Produces low diene rubber. A diene rubber having a low Mooney viscosity is excellent in processability, productivity and extrudability, and can be highly filled as a reinforcing agent.

<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 and cyclohexane 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.

  Regarding the amount of the transition metal catalyst to be used, if the addition amount of the transition metal catalyst is small, the conjugated diene monomer with respect to the transition metal catalyst increases, so that the Mooney viscosity of the resulting diene rubber increases. On the other hand, from the viewpoint of lowering the Mooney viscosity of the resulting diene rubber, the addition amount of the transition metal catalyst may be large, but the effect is limited, and the cost increases as the addition amount is increased. End up.

  Therefore, in the present invention, the amount of the conjugated diene monomer added to 1 mmol of the transition metal catalyst is in the range of 100 to 1400 mol. In this way, a diene rubber having a low Mooney viscosity can be efficiently produced by relatively reducing the amount of monomer relative to the transition metal catalyst. The amount of the conjugated diene monomer added to 1 mmol of the transition metal catalyst is preferably in the range of 200 to 1000 mol, more preferably in the range of 300 to 850 mol, and still more preferably in the range of 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.

  In addition, since the organometallic promoter exhibits a function as a promoter by reacting with water added to the monomer solution, the relationship with the amount of water may be important. When the amount of the organometallic promoter added to water is large, the Mooney viscosity of the resulting diene rubber tends to be high, and the processability tends to decrease. On the other hand, if the amount of the organometallic promoter added to water is small, the resulting Moonene viscosity of the diene rubber is low, but the yield tends to decrease.

  Therefore, in the present invention, the amount of the organometallic promoter added per 1 mol of water is preferably in the range of 1.3 to 2.5 mol. Thus, by adjusting the amount of the organometallic promoter relative to water, a diene rubber having a low Mooney viscosity can be produced efficiently. The addition amount of the organometallic promoter relative to 1 mol of water is more preferably in the range of 1.4 to 2.0 mol, and further preferably in the range of 1.5 to 1.8 mol.

<Molecular weight regulator>
In the present invention, a molecular weight modifier is 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 -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 molecular weight modifier used, if the amount of molecular weight modifier added is small, the Mooney viscosity of the resulting diene rubber will be high. On the other hand, from the viewpoint of lowering the Mooney viscosity of the obtained diene rubber, the amount of the molecular weight modifier added may be large, but in this case, the yield of the diene rubber obtained is reduced.

Therefore, in the present invention, the addition amount of the molecular weight modifier with respect to 1 m ³ of the monomer liquid is set in the range of 7 to 50 mol. Thus, by relatively increasing the amount of the molecular weight modifier with respect to the monomer liquid, a diene rubber having a low Mooney viscosity can be produced efficiently. The amount of the molecular weight modifier added to 1 m ³ of the monomer liquid is preferably in the range of 8 to 40 mol, more preferably in the range of 10 to 30 mol, and still more preferably in the range of 15 to 20 mol.

<Anti-gelling agent>
In the present invention, an antigelling agent can be 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 to be used, the amount of the antigelling agent added to the monomer liquid 1 m ³ is preferably in the range of 1 to 1000 mmol, more preferably in the range of 3 to 500 mmol, and more preferably 5 to 300 mmol. More preferably, it is set as the range.

<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 a molecular weight modifier (preferably further an anti-gelling agent) 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 → Molecular weight regulator → Organometallic promoter → Transition metal catalyst (2) Water → Organometallic promoter → Molecular weight regulator → Transition metal catalyst (3) Molecular weight regulator → Water → Organometallic promoter → Transition metal Catalyst (4) Molecular weight regulator → Organometallic promoter → Water → Transition metal catalyst (5) Organometallic promoter → Water → Molecular weight regulator → Transition metal catalyst (6) Organometallic promoter → Molecular weight regulator → Water → Transition A metal catalyst is mentioned. The anti-gelling agent can be added, for example, at an arbitrary timing before adding the transition metal catalyst, but it is preferable to add the anti-gelling agent at the same time as the molecular weight adjusting agent or immediately before or after the molecular weight adjusting 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 measurement of Mw and Mw / Mn can be performed using the GPC apparatus 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.

  The gel content can be calculated as follows. First, 10 g of rubber and 400 mL of toluene are placed in an Erlenmeyer flask and completely dissolved at room temperature (25 ° C.). Then, it filters using the filter which installed the 200 mesh metal mesh, The gel adhering to the metal mesh after filtration is vacuum-dried, and a weight is measured by making it into a toluene insoluble content. And the ratio of the toluene insoluble matter to the sample rubber is calculated.

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 diene rubber produced by the method of the present invention is characterized by a relatively low Mooney viscosity (ML _{1 + 4} ) as described above. The method of the present invention is suitable for producing a diene rubber having ML _{1 + 4} of 45 or less, particularly suitable for producing a diene rubber having ML _{1 + 4} of 10 or more and 40 or less, and ML _{1 + 4} is 20 or more and 35 or less. Most suitable for the production of diene rubber. In addition, the measuring method of ML _{1 + 4} will be described in detail in Examples described later.

Furthermore, the diene rubber produced by the method of the present invention preferably has low molecular linearity as described above. Here, the linearity of the molecule refers to the linearity of the rubber molecule, and the 5% by weight toluene solution viscosity (T _cp [cps]) and the Mooney viscosity (ML _{1 + 4} ) at 100 ° C. measured based on JIS-K6300. Ratio (T _cp / ML _{1 + 4} ) as an index. T _cp indicates the degree of molecular entanglement in the concentrated solution, and when T _cp / ML _{1 + 4} increases, the degree of branching decreases and the linearity increases. That is, the lower the T _cp / ML _{1 + 4} is, the lower the linearity of the rubber molecule is, and it has a highly branched polymer structure. Further, the higher the T _cp / ML _{1 + 4} , the higher the linearity of the rubber molecule and the lower the polymer structure.

The method of the present invention is suitable for producing a diene rubber having T _cp / ML _{1 + 4} of 2.5 or less, and for producing a diene rubber having T _cp / ML _{1 + 4} of 1.0 or more and 2.4 or less. Especially suitable.

  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.

  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: 32% by weight, C4 fraction: 31% by weight, cyclohexane: 37% by weight) was added. While stirring the monomer solution at 400 rpm, 1.71 mmol of water was added and stirred at 25 ° C. for 30 minutes. Furthermore, 16.9 mmol of cyclooctadiene as a molecular weight modifier, 15 μmol of dilauryl thiodipropionate as an antigelling agent, and 3 mmol of diethylaluminum chloride as a co-catalyst were added and stirred at 25 ° C. for 5 minutes. Thereafter, the temperature of the monomer solution was raised to 60 ° C., and 5.5 μmol of cobalt octoate as a catalyst was added to carry out cis-1,4 polymerization. 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. , 92.7 g of 1,4-polybutadiene rubber was obtained.

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

(Molecular weight distribution)
The molecular weight distribution of the 1,4-polybutadiene rubber obtained was a GPC device (manufactured by Tosoh Corporation, trade name: HLC) in which two columns (made by Showa Denko, trade name: Shodex GPC KF-805L column) were connected in series. -8220 GPC), and calculated based on a standard polystyrene examination line 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).

(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>
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: 33 wt%, C4 fraction: 45 wt%, cyclohexane: 22 wt%) was added. While stirring the monomer solution at 400 rpm, 1.71 mmol of water was added and stirred at 25 ° C. for 30 minutes. Furthermore, 8.2 mmol of cyclooctadiene as a molecular weight modifier, 15 μmol of dilauryl thiodipropionate as an antigelling agent, and 3.0 mmol of diethylaluminum chloride as a cocatalyst were added and stirred at 25 ° C. for 5 minutes. Thereafter, the temperature of the monomer solution was raised to 50 ° C., and 10.4 μmol of cobalt octoate as a catalyst was added thereto, except that cis-1,4 polymerization was performed at 50 ° C. for 25 minutes. 1,4-polybutadiene rubber was produced in the same manner. Then, Mw / Mn, ratio of cis-1,4 structure, 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. did. These results are shown in Table 1.

<Comparative Example 1>
A 1,4-polybutadiene rubber was produced in the same manner as in Example 1 except that the amount of the molecular weight modifier added to 1 mol of water was changed as shown in Table 1 by adjusting the amount of cyclooctadiene added. did. Then, Mw / Mn, ratio of cis-1,4 structure, 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. did. These results are shown in Table 1.

<Comparative example 2>
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: 0.07 m) substituted with nitrogen gas 0 L (1,3-butadiene: 32% by weight, C4 fraction: 31% by weight, cyclohexane: 37% by weight) was added. While stirring the monomer solution at 400 rpm, 1.71 mmol of water was added and stirred at 25 ° C. for 30 minutes. Furthermore, 12.8 mmol of cyclooctadiene as a molecular weight modifier, 15 μmol of dilauryl thiodipropionate as an antigelling agent, and 3.0 mmol of diethylaluminum chloride as a cocatalyst were added, and the mixture was stirred at 25 ° C. for 5 minutes. Thereafter, the temperature of the monomer liquid was raised to 60 ° C., and 2.7 μmol of cobalt octoate as a catalyst was added to perform cis-1,4 polymerization. , 4-polybutadiene rubber was produced. Then, Mw / Mn, ratio of cis-1,4 structure, 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. did. 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 ML _{1 + 4} .

Claims (6)

A method for producing a diene rubber having a 5 wt% toluene solution viscosity (T _cp [cps]) of 39.0 or less and a Mooney viscosity (ML _{1 + 4} ) at 100 ° C. measured based on JIS-K6300 of 35 or less. There,
A step of polymerizing the conjugated diene monomer by adding water, a transition metal catalyst, an organic metal promoter and a molecular weight regulator to a monomer liquid containing a conjugated diene monomer and an organic solvent;
The amount of the conjugated diene monomer added to 1 mmol of the transition metal catalyst is 100 to 750 mol,
Method for producing a diene rubber addition amount is 15~50mol of the molecular weight modifier for said monomer liquid 1 m ^3.   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 1.3 to 2.5 mol.   The method for producing a diene rubber according to claim 1 or 2, wherein the molecular weight modifier is a non-conjugated diene.   The method for producing a diene rubber according to any one of claims 1 to 3, wherein the transition metal catalyst is a cobalt-based catalyst.   The method for producing a diene rubber according to any one of claims 1 to 4, wherein the organometallic promoter is an organoaluminum compound.   The method for producing a diene rubber according to any one of claims 1 to 5, wherein the conjugated diene monomer is 1,3-butadiene and the diene rubber is 1,4-polybutadiene rubber.