JP2009007507A - Reinforced polybutadiene and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforced polybutadiene rubber with improved reinforcing effect by a syndiotactic 1,2-polybutadiene and to provide a method for producing the same. <P>SOLUTION: The invention relates to a reinforced polybutadiene rubber and a method for producing the same which comprises conducting cis-1,4 polymerization of 1,3-butadiene and then conducting syndiotactic-1,2 polymerization under conditions wherein the agitation parameter nd<SP>(2/3)</SP>>35 (n; agitation speed (rpm), d: effective radius of the agitation (m)), and d/D≥0.5, where D (m) is a radius of the reaction chamber. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reinforced polybutadiene comprising cis-1,4-polybutadiene and syndiotactic 1,2-polybutadiene and a method for producing the same.

  Vinyl cis polybutadiene rubber (hereinafter referred to as reinforced polybutadiene rubber) in which syndiotactic 1,2-polybutadiene crystals are dispersed in 1,4-cis-butadiene rubber is a product compared to conventional 1,4-cis-butadiene rubber. It is known as a material that makes it easy to increase the hardness, increase the elastic modulus, and improve the workability.

In Japanese Patent Publication No. 49-17666 (Patent Document 1) and Japanese Patent Publication No. 49-17667 (Patent Document 2), as a method for producing a reinforced polybutadiene rubber, 1,3-butadiene is used in an inert organic solvent. water, using a soluble cobalt compound and the general formula AlR _n X _3-n catalyst obtained from organic halides representable by cis-1,4 polymerization, followed by soluble cobalt compounds of the general formula AlR ₃ in this polymerization system A method of syndiotactic 1,2 polymerization of 1,3-butadiene using a syndiotactic 1,2 polymerization catalyst obtained from an organoaluminum compound and carbon disulfide that can be expressed is disclosed. Further, it is described that the obtained reinforced polybutadiene rubber is excellent in tear strength and bending crack resistance without impairing the properties of 1,4-cis-butadiene rubber.

  Further, JP 2000-44633 A (Patent Document 3) discloses that 1,3-butadiene is converted from a halogen-containing organoaluminum compound, a soluble cobalt compound, and water in an inert organic solvent mainly composed of a C4 fraction. In the polymerization reaction mixture obtained by cis-1,4 polymerization using the following catalyst system, and further by a syndiotactic 1,2 polymerization catalyst obtained from a soluble cobalt compound, a trialkylaluminum compound and carbon disulfide, A method for producing a new reinforced polybutadiene rubber by syndiotactic 1,2 polymerization is provided. The obtained reinforced polybutadiene rubber has a boiling n-hexane insoluble content of 3 to 30% by weight and a boiling n-hexane soluble content of 97 to 70% by weight, and the boiling n-hexane insoluble content is a short fiber crystal. It is disclosed that it is syndiotactic 1,2-polybutadiene having a dispersion form of cis-1,4-polybutadiene having a cis structure soluble in boiling n-hexane of 90% or more. It describes that the moldability, tensile stress, tensile strength, bending crack growth resistance, etc. of 1,4-polybutadiene rubber are improved.

  However, these reinforced polybutadiene rubbers may be inferior to cis-1,4-polybutadiene rubber in wear resistance and heat generation, and contribute to resource and energy savings due to environmental problems such as global warming in recent years. There has been a strong demand for materials to be made, for example, materials that facilitate high hardness and high rigidity for weight reduction and thinning, and further improvements in characteristics are desired.

Japanese Patent Publication No.49-17666 Japanese Patent Publication No.49-17667 JP 2000-44633 A

  It is an object of the present invention to provide a reinforced polybutadiene rubber having a higher reinforcing effect by syndiotactic 1,2-polybutadiene and a method for producing the same.

In the present invention, 1,3-butadiene is cis-1,4 polymerized, and subsequently stirring parameters nd ^(2/3) (n: stirring speed (rpm), d: effective stirring diameter (m)) of 35 or more are stirred. The present invention relates to a reinforced polybutadiene rubber obtained in a syndiotactic 1,2 polymerization step in which the relationship between an effective diameter d (m) and a reaction vessel diameter D (m) is d / D ≧ 0.5, and a method for producing the same.

  Further, a value (ΔML / HI) obtained by dividing the difference (ΔML) between the Mooney viscosity of the reinforced polybutadiene rubber and the Mooney viscosity of the boiling n-hexane soluble component (ΔML) by the amount of boiling n-hexane insoluble matter (HI) is 2. The present invention relates to a polybutadiene rubber that is 7 or more.

  Moreover, it is related with said polybutadiene rubber whose content rate of a boiling n-hexane insoluble content is 1 to 25 weight%.

  According to the present invention, it is possible to provide a reinforced polybutadiene rubber having a very high reinforcing effect by syndiotactic 1,2-polybutadiene.

  The reinforced polybutadiene rubber of the present invention can be produced by a two-stage polymerization method. That is, by performing cis-1,4 polymerization in the first stage and continuing syndiotactic 1,2-polymerization without stopping the polymerization as it is, syndiotactic 1,2 in cis-1,4-polybutadiene is performed. A reinforced polybutadiene rubber in which 2-polybutadiene crystals are dispersed is obtained.

  Solvents used for the production include linear aliphatic hydrocarbons such as n-hexane, butane, heptane and pentane, cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane, 1-butene, cis-2-butene, trans- Examples thereof include olefinic hydrocarbons of C4 fraction such as 2-butene, hydrocarbon solvents such as mineral spirit, solvent naphtha and kerosene, and halogenated hydrocarbon solvents such as methylene chloride. These may be used alone or in combination. Among them, a solvent containing cyclohexane is preferably used, and in particular, a mixture of cyclohexane and a C4 fraction such as cis-2-butene and trans-2-butene is preferably used.

  As a catalyst for cis-1,4 polymerization, a catalyst comprising a cobalt compound, an organoaluminum compound, and water can be used.

  As the cobalt compound, a cobalt salt or complex is preferably used. Particularly preferred are cobalt chloride, cobalt bromide, cobalt nitrate, cobalt octylate, cobalt naphthenate, cobalt acetate, cobalt malonate, cobalt bisacetylacetonate, trisacetylacetonate, ethyl acetoacetate. Examples thereof include ester cobalt, cobalt halide triarylphosphine complex, trialkylphosphine complex, organic base complexes such as pyridine complex and picoline complex, and ethyl alcohol complex.

The amount of these cobalt compounds used is usually in the range of 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ mol, preferably 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ mol, relative to 1 mol of butadiene.

Examples of the organoaluminum compound include trialkylaluminum compounds represented by R ¹ ₃ Al (wherein R ¹ represents a hydrocarbon group having 1 to 10 carbon atoms), R ² _3-n AlX _n (wherein , R ² is a hydrocarbon group having 1 to 10 carbon atoms, X represents a halogen, and n is a number of 1 to 2). These can be used alone or as a mixture.

Among the organoaluminum compounds, triethylaluminum compounds represented by R ¹ ₃ Al (wherein R ¹ represents a hydrocarbon group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms) include triethyl. Aluminum, trimethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum and the like can be mentioned. Of these, triethylaluminum is preferable.

  The amount of these trialkylaluminums used is usually in the range of 10 to 5000 mol, preferably 50 to 1000 mol, per 1 mol of the cobalt compound.

Among the organoaluminum compounds, R ² _3-n AlX _n (wherein R ² is a hydrocarbon group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, X is halogen, and n is 1 to 1). As the halogen-containing aluminum compound represented by 2), dialkylaluminum halides, dialkylaluminum halides such as dialkylaluminum bromides, alkylaluminum sesquichlorides, alkylaluminum sesquihalides such as alkylaluminum sesquibromides, and alkylaluminum dichlorides. And alkyl aluminum dihalides such as alkyl aluminum dibromide. Specific examples of the compound include diethyl aluminum monochloride, diethyl aluminum monobromide, dibutyl aluminum monochloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, dicyclohexyl aluminum monochloride, diphenyl aluminum monochloride. Of these, diethylaluminum monochloride is preferable.

  The amount of these halogen-containing aluminum compounds used is such that the ratio (X / Al) of X atoms in the halogen-containing aluminum compound to Al atoms in the trialkylaluminum and halogen-containing aluminum is 0 to 1, preferably 0.1. It is -0.9, Most preferably, it is 0.25-0.75.

  The usage-amount of water is 0.1-1.45 mol normally with respect to 1 mol of aluminum compounds, Preferably it is 0.2-1.2 mol.

  The order of addition of the catalyst components is not particularly limited, but it is preferable to mix and ripen trialkylaluminum and halogen-containing aluminum in an inert solvent, the aging time is 0.1 to 24 hours, and the aging temperature is 0 to 0. 80 ° C. is preferred. Moreover, it is preferable to further ripen by adding water to this ripening liquid, the aging time is preferably 0.1 to 24 hours, and the aging temperature is preferably 0 to 80 ° C.

  Known molecular weight regulators at the time of polymerization, for example, non-conjugated dienes such as hydrogen, cyclooctadiene, and allene, or α-olefins such as ethylene, propylene, and butene-1 can be used. Moreover, in order to suppress the production | generation of a gel, a well-known antigelling agent can be used.

  The polymerization temperature is preferably in the range of 0 ° C to 100 ° C, particularly preferably in the range of 20 ° C to 80 ° C. The polymerization time is preferably in the range of 5 minutes to 5 hours, particularly preferably 10 minutes to 2 hours. The polymerization pressure is performed under normal pressure or a pressure up to about 10 atmospheres (gauge pressure).

  Polymerization is preferably carried out so that the polymer concentration after cis-1,4 polymerization is 5 to 26% by weight. The polymerization tank is performed by connecting one tank or two or more tanks. The polymerization is carried out by stirring and mixing the solution in a polymerization tank (polymerizer). As a polymerization tank used for the polymerization, a polymerization tank equipped with a high-viscosity liquid stirring apparatus, for example, an apparatus described in JP-B-40-2645 can be used.

  Although 1,3-butadiene may or may not be added to the cis-1,4 polymerization reaction mixture obtained as described above, syndiotactic 1,2 polymerization is continued in this polymerization system.

As a catalyst for syndiotactic 1,2 polymerization, a trialkylaluminum compound represented by R ¹ ₃ Al (wherein R ¹ represents a hydrocarbon group having 1 to 10 carbon atoms), a sulfur compound, and If necessary, a catalyst system comprising a cobalt compound is used.

The trialkylaluminum compound represented by R ¹ ₃ Al (wherein R ¹ represents a hydrocarbon group having 1 to 10 carbon atoms) and the cobalt compound were used in the cis-1,4 polymerization. Compounds.

  The trialkylaluminum compound is preferably used in an amount of 0.1 mmol or more, particularly 0.5 to 50 mmol, per mol of 1,3-butadiene.

  Examples of the sulfur compound include carbon disulfide, phenyl isothiocyanate, and xanthate compound. Among these, carbon disulfide is preferable.

  The sulfur compound preferably does not contain moisture, and the concentration is preferably 20 mmol / L or less, particularly preferably 0.01 to 10 mmol / L.

  The polymerization temperature is preferably in the range of 0 ° C to 100 ° C, particularly preferably in the range of 20 ° C to 80 ° C. The polymerization time is preferably in the range of 5 minutes to 5 hours, particularly preferably in the range of 10 minutes to 2 hours. Further, 1 to 50 parts by weight, preferably 1 to 20 parts by weight of 1,3-butadiene per 100 parts by weight of the cis polymerization solution is added to the polymerization system, whereby 1,2-polybutadiene at the time of 1,2 polymerization is added. Yield can be increased.

  Polymerization is preferably performed so that the polymer concentration after syndiotactic 1,2 polymerization is 6 to 30% by weight. The polymerization tank is performed by connecting one tank or two or more tanks. The polymerization is carried out by stirring and mixing the polymerization solution in a polymerization tank (polymerizer). As the polymerization tank used for the polymerization, use of a polymerization tank equipped with a high-viscosity liquid stirrer, for example, the apparatus described in JP-B-40-2645, because the viscosity becomes higher during 1,2 polymerization and the polymer tends to adhere. Can do.

Stirring parameters nd ^(2/3) (n: stirring speed (rpm), d: effective stirring diameter (m)) during syndiotactic 1, 2 polymerization are preferably 35 or more, more preferably 40 or more, particularly Preferably it is 45 or more.

  Further, in order to obtain uniformity in the system, the relationship between the effective stirring diameter d (m) and the reaction vessel diameter D (m) is preferably d / D ≧ 0.5, more preferably d / D ≧ 0.6, particularly Preferably d / D ≧ 0.7.

  Furthermore, a known anti-aging agent can be added according to a conventional method. Anti-aging agents include phenol-based 2,6-di-t-butyl-p-cresol (BHT), phosphorus-based trinonylphenyl phosphite (TNP), and sulfur-based dilauryl-3,3′-thiodipropio. Nate (TPL). These may be used alone or in combination of two or more, and the addition amount is 0.001 to 5 parts by weight with respect to 100 parts by weight of the polymer.

  Next, a polymerization terminator is added to the polymerization system and stopped. For example, after completion of the polymerization reaction, a method of introducing this polymerization solution into a polymerization stop tank in which a large amount of polar solvent such as methanol or ethanol or polar solvent such as water is supplied, inorganic acid such as hydrochloric acid or sulfuric acid, acetic acid, benzoic acid, etc. It is a method known per se, such as a method of introducing an organic acid or hydrogen chloride gas into the polymerization solution. Thereafter, the produced polymer is separated, washed and dried according to a usual method.

The Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of the reinforced polybutadiene rubber obtained as described above is preferably in the range of 20 to 150, particularly in the range of 30 to 110, from the viewpoint of processability and strength. Is preferred.

  The boiling n-hexane insoluble content (HI) of the reinforced polybutadiene rubber is preferably 1 to 25% by weight, more preferably 2 to 22% by weight, and particularly preferably 2.5 to 19% by weight. The melting point is 170 ° C. or higher, particularly 190 to 220 ° C., and the reduced viscosity (ηsp / c) is preferably 0.5 or higher. Here, most of the HI is syndiotactic 1,2-polybutadiene, and the boiling n-hexane soluble component is 1,4-cis-polybutadiene rubber.

The cis-1,4 structure content of the reinforced polybutadiene rubber is preferably 90% or more, particularly preferably 95% or more. The weight average molecular weight (M _w ) is preferably 300,000 to 800,000, particularly preferably 400,000 to 700,000.

The Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of the boiling n-hexane soluble content is preferably 10 to 130, particularly preferably 15 to 80. Moreover, 10-300 are preferable and, as for the 5% toluene solution viscosity (Tcp) measured at 25 degreeC, 20-200 are especially preferable. Furthermore, the intrinsic viscosity ([η]) is preferably 1.0 to 5.0, and particularly preferably 1.0 to 4.0.

The ratio (Tcp / ML _{1 + 4} ) of the 5% toluene solution viscosity (Tcp) measured at 25 ° C. to the boiling n-hexane soluble content and the Mooney viscosity (ML _{1 + 4} ) at 100 ° C. is preferably 1 or more. 1.5 or more is preferable.

  The reinforcing effect by syndiotactic 1,2-polybutadiene was obtained by dividing the difference between the Mooney viscosity of the reinforced polybutadiene rubber and the Mooney viscosity of soluble n-hexane (ΔML) by the amount of boiling n-hexane insoluble (HI). It can be represented by a value (ΔML / HI). That is, the larger the ΔML / HI, the higher the reinforcing effect.

  ΔML / HI in the present invention is preferably 2.7 or more, more preferably 3.0 or more, and particularly preferably 3.5 or more.

  The reinforced polybutadiene rubber obtained by the present invention is used for rubber applications that require rigidity, mechanical characteristics and fracture characteristics such as tires, hoses, belts and other various industrial products.

Hereinafter, the present invention will be specifically described with reference to examples. In addition, the measuring method of a physical property is as follows.
(1) Mooney viscosity (ML _{1 + 4} ): Measured at 100 ° C. according to JIS K6300.
(2) Toluene solution viscosity (Tcp): The viscosity of a 5 wt% toluene solution at 25 ° C was measured.
(3) Boiling n-hexane insoluble matter (HI): 2 g of reinforced polybutadiene rubber was Soxhlet extracted with 200 ml of n-hexane for 4 hours, and the remainder of the extraction was shown in parts by weight.
(4) Reduced viscosity (ηsp / c): Measured with an orthodichlorobenzene solution at 135 ° C. and 0.20 g / dl.
(5) Melting point (T _m ): Determined by the peak temperature of the endothermic curve by a differential scanning calorimeter (DSC).
(6) Weight average molecular weight (M _w ): Tetrahydrofuran solution, gel permeation chromatography (GPC, manufactured by Tosoh Corporation, HLC-802A) at 40 ° C., based on a calibration curve using standard polystyrene, weight average molecular weight (M _w ), The number average molecular weight (M _n ) and molecular weight distribution (M _w / M _n ) were determined.
(7) Microstructure: 740 cm in the infrared absorption spectrum ^-1 (cis), 967 cm ^-1 (trans), was calculated from the absorption intensity ratio of 910 cm ^-1 (vinyl).
(8) Intrinsic viscosity ([η]): Measured with a toluene solution at 30 ° C.

Example 1
Polymer solution 1.0L (butadiene: 31.5 wt%, 2- in a stainless steel reaction tank with a stirrer (stirring blade diameter 0.06m) with an internal volume of 1.5L (tank diameter 0.08m) replaced with nitrogen gas, 2- Butenes: 28.8 wt%, cyclohexane: 39.7 wt%). Next, under stirring at 400 rpm, 1.7 mmol of water, 3.0 mmol of diethylaluminum chloride, 0.25 mmol of carbon disulfide, 13.0 mmol of cyclooctadiene, 0.005 mmol of cobalt octoate were added, and cis- 1,4 polymerization was performed.
Thereafter, the stirring speed was set to 750 rpm, the stirring parameter nd ^(2/3) (n: stirring speed, d: stirring effective radius) was set to 115, and 3.9 mmol of triethylaluminum and 0.004 mmol of cobalt octoate were added at 40 ° C. Syndiotactic 1,2 polymerization was performed for 20 minutes. Ethanol containing an antioxidant was added thereto to stop the polymerization, and then unreacted butadiene and 2-butenes were removed by evaporation to obtain 103 g of reinforced polybutadiene rubber.
This polymer had a Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of 63.6, a boiling n-hexane insoluble content (HI) of 2.7%, a melting point of HI (T _m ) of 204.2 ° C., and a reduced viscosity of HI. (Ηsp / c) was 2.3.
Moreover, ML _{1 + 4} of the boiling n-hexane soluble content is 29.0, 5 wt% toluene solution viscosity (Tcp) at 25 ° C. is 54.0, weight average molecular weight (M _w ) is 465,000, cis-1, The four structure was 98.5% and the intrinsic viscosity ([η]) was 1.5.

(Example 2)
The same procedure as in Example 1 was performed except that the cobalt octoate added during syndiotactic 1,2 polymerization was 0.010 mmol and the amount was changed to each HI amount shown in Table 1.

(Example 3)
The same procedure as in Example 1 was performed except that the cobalt octoate added during syndiotactic 1,2 polymerization was 0.050 mmol and the amount was changed to each HI amount shown in Table 1.

Example 4
The same procedure as in Example 1 was performed except that the cobalt octoate added during syndiotactic 1,2 polymerization was 0.120 mmol and the amount was changed to each HI amount shown in Table 1.

(Example 5)
The same procedure as in Example 1 was performed except that the stirring parameter during syndiotactic 1,2 polymerization was changed to 77.

(Example 6)
The same procedure as in Example 1 was performed except that the stirring parameter at the time of syndiotactic 1,2 polymerization was set to 35.

(Example 7)
The same procedure as in Example 1 was performed except that the amount of cyclooctadiene used in the cis-1,4 polymerization was changed to 11.5 mmol.
The Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of the boiling n-hexane soluble content of the reinforced polybutadiene thus obtained was 41.1, the 5 wt% toluene solution viscosity (Tcp) at 25 ° C. was 82.2, and the weight average molecular weight. (M _w ) was 550,000, the 1,4-cis structure content was 98.5%, and the intrinsic viscosity ([η]) was 2.0.

(Example 8)
The same procedure as in Example 1 was performed except that the temperature during the syndiotactic 1,2 polymerization was 60 ° C.
The Mooney viscosity (ML _{1 + 4} ) at 100 ° C. of the boiling n-hexane soluble content of the reinforced polybutadiene thus obtained was 29.0, the 5 wt% toluene solution viscosity (Tcp) at 25 ° C. was 54.0, and the weight average molecular weight. (M _w ) was 465,000, the 1,4-cis structure content was 98.5%, and the intrinsic viscosity ([η]) was 1.5.

(Comparative Examples 1-4)
The same procedure as in Examples 1 to 4 was conducted except that the stirring parameter during syndiotactic 1,2 polymerization was 31.

(Comparative Examples 5 and 6)
The same procedure as in Examples 7 and 8 was conducted except that the stirring parameter at the time of syndiotactic 1,2 polymerization was 31.

Claims (4)

1,3-Butadiene is cis-1,4 polymerized, followed by stirring parameters nd ^(2/3) (n: stirring speed (rpm), d: effective stirring diameter (m)) of 35 or more, effective stirring diameter d A polybutadiene rubber obtained in a process of syndiotactic 1,2 polymerization with the relationship between (m) and reaction vessel diameter D (m) being d / D ≧ 0.5. The value (ΔML / HI) obtained by dividing the difference between the Mooney viscosity of the reinforced polybutadiene rubber and the Mooney viscosity of the boiling n-hexane soluble component (ΔML) by the amount of boiling n-hexane insoluble matter (HI) (ΔML / HI) is 2.7 or more. The polybutadiene rubber according to claim 1. The polybutadiene rubber according to claim 1 or 2, wherein the content of boiling n-hexane insoluble matter is 1 to 25% by weight. In a method of cis-1,4 polymerization of 1,3-butadiene, followed by syndiotactic 1,2 polymerization, stirring parameter nd ^(2/3) (n: stirring speed ( rpm), d: effective stirring diameter (m)) is 35 or more, and the relationship between effective stirring diameter d (m) and reaction tank diameter D (m) is d / D ≧ 0.5. A method for producing polybutadiene rubber.