TW201609839A - Polybutadiene and rubber composition - Google Patents

Abstract

One aspect of the present invention relates to a polybutadiene in which the ratio (Tcp/ML1+4) between the 5% toluene solution viscosity (Tcp) measured at 25 DEG C and the Mooney viscosity (ML1+4) measured at 100 DEG C is at least 1.3 but not more than 5.0, the molecular weight distribution (Mw/Mn) is at least 2.0 but less than 4.0, and the cold flow rate (CF) is not more than 5.5 mg/min.

Description

Polybutadiene and rubber composition

This invention relates to polybutadiene. Further, the present invention relates to a rubber composition containing the polybutadiene and a rubber composition for a tire.

Polybutadiene, in the so-called microstructure, a bond portion (1,4-structure) formed by polymerization at the 1,4-position and a polymerization at a 1,2-position are coexisted in the molecular chain. Bonding part (1,2-structure). The 1,4-structure is subdivided into two types, a cis structure and a trans structure. On the other hand, the 1,2-structure adopts a structure in which a vinyl group is used as a side chain. It is also known that such a micro-butadiene having a different microstructure can be produced by using a polymerization catalyst, and the properties are used in various applications.

In particular, the linearity of the molecule is high, that is, the polybutadiene having a small degree of branching has characteristics of excellent wear resistance, low heat build-up, and excellent rebound elasticity. The linearity index is the ratio of the 5% toluene solution viscosity (Tcp) measured at 25 ° C to the Mohs viscosity (ML _{1 + 4} ) at 100 ° C (Tcp/ML _{1 + 4 )} . Tcp represents the degree of entanglement of the molecule in a thick solution, and it is considered that the larger Tcp/ML _{1 + 4} , the smaller the branching degree and the greater the linearity.

However, such a polybutadiene having a large Tcp/ML _{1 + 4 and} high molecular linearity (that is, a small degree of branching) exhibits high cold flow characteristics, low storage stability, and is stored and transported. There are times when problems occur.

As a method of improving the cold flow, Patent Documents 1 to 3 disclose that a conjugated diene polymer obtained by polymerizing a conjugated diene compound such as polybutadiene and a specific compound (modifier) are reacted. (sex) to improve the cold flow characteristics (ie, suppress cold flow).

Patent Document 4 discloses a modified polybutadiene obtained by modifying a polybutadiene having a specific characteristic in the presence of a transition metal catalyst in the case of polybutadiene having improved cold flow characteristics.

Further, Patent Document 5 discloses a polymer composition which is a polymer composition such as polybutadiene which is improved in cold flow resistance (that is, suppresses cold flow) which can be produced at a low cost without a modification step, wherein The cerium oxide is dispersed in the polymer (present in a state of being highly dispersed) in an amount of more than 0 parts by weight and not more than 5 parts by weight based on 100 parts by weight of the polymer. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2001-139633 (Patent Document 3) JP-A-2009-120757 (Patent Document 4) Japanese Patent Laid-Open No. 2002-302512 Bulletin [Patent Document 5] Japanese Patent Laid-Open Publication No. 2014-1315

[Questions to be solved by the invention]

An object of the present invention is to provide a polybutadiene having a large molecular linearity index Tcp/ML _{1 + 4} and excellent cold flow characteristics. Further, an object of the present invention is to provide a polybutadiene which has excellent characteristics possessing polybutadiene having a small degree of branching, such as excellent abrasion resistance, low heat build-up, rebound elasticity, and excellent cold flow characteristics. [How to solve the problem]

The present invention relates to the following matters. A polybutadiene having a ratio of a 5% toluene solution viscosity (Tcp) measured at 25 ° C to a Mohs viscosity (ML _{1 + 4} ) at 100 ° C (Tcp/ML _{1 + 4} ) of 1.3 or more Below 5.0, the molecular weight distribution (Mw/Mn) is 2.0 or more and less than 4, and the cold flow rate (CF) is 5.5 mg/min or less. 2. The polybutadiene of 1, which has a Mohs viscosity (ML _{1 + 4} ) at 100 ° C of 25 or more and 60 or less.

3. A polybutadiene having a number of long chain branching points per 10,000 of butadiene monomer units as determined by ¹³ C-NMR measurement of hydrogenated polybutadiene (only long chain branch points are referred to by 2 More than 9 branches of the above-mentioned butadiene unit having a carbon number of 6 or more are bonded to the branch point of the main chain), and the storage elasticity of the 50% by mass solution of the liquid paraffin of the polybutadiene and the 10% by mass solution Y=G'/ when the ratio G′′ is determined by the measurement of the angular frequency dependence of the coefficient G′ and the loss elastic coefficient G′′, and the concentration conversion G′ is X=G′′/C ² =20,000 Pa. The ratio of Y defined by C ² (but C is the concentration of the solution) [Y _(50%) / Y _(10%) (but Y _(50%) is determined from the measurement of 50% by mass of the liquid paraffin solution, Y _(10%) is determined from the measurement of a liquid paraffin 10% by mass solution.)] is greater than 2.

4. A polybutadiene having a number of long chain branch points per 10,000 butadiene monomer units determined by ¹³ C-NMR measurement of hydrogenated polybutadiene (only long chain branch points are referred to by 2 The number of branching chains having 6 or more carbon atoms formed by the butadiene units bonded to the main chain is 9 or less, and the cold flow rate (CF) is 5.5 mg/min or less.

5. A polybutadiene having a ratio of a 5% toluene solution viscosity (Tcp) measured at 25 ° C to a Mohs viscosity (ML _{1 + 4} ) at 100 ° C (Tcp/ML _{1 + 4} ) of 1.3 or more , the conversion of the angular dependence of the density dependence of the 50% by mass solution of the polybutadiene and the storage elastic coefficient G' of the 10% by mass solution and the loss elastic coefficient G''G' becomes the ratio Y of Y=G'/C ² (where C represents the solution concentration) when X=G''/C ² =20,000 Pa [Y _(50%) /Y _(10%) Y _(50%) is obtained from the measurement of a 50% by mass solution of a flowing paraffin, and Y _(10%) is obtained by measuring 値 from a liquid paraffin 10% by mass solution.)] is more than 2.

6. The polybutadiene according to any one of items 1 to 5, wherein the cis-1,4-structure content is 90% or more.

A rubber composition comprising the polybutadiene according to any one of 1. to 6. A rubber composition for a tire, which comprises the polybutadiene according to any one of 1. to 6. 9. The rubber composition for tires according to 8, which comprises a diene polymer other than polybutadiene and a rubber reinforcing agent. 10. The rubber composition for a tire according to 9, wherein the diene polymer is at least one of natural rubber, styrene-butadiene rubber, and polyisoprene. 11. The rubber composition for a tire according to 9. or 10. wherein the rubber reinforcing agent is carbon black and/or cerium oxide. A tire composition for use in a rubber composition for a tire according to any one of items 8 to 11. [Effects of the Invention]

According to the present invention, it is possible to provide a polybutadiene which is relatively large in Tcp/ML _{1 + 4} and excellent in cold flow characteristics as an index of molecular linearity. Further, according to the present invention, it is also possible to provide a polybutadiene having excellent characteristics possessing polybutadiene having a small degree of branching, such as excellent abrasion resistance, low heat build-up, rebound elasticity, and excellent cold flow characteristics. The polybutadiene of the present invention is excellent in abrasion resistance, low heat build-up, rebound elasticity, and the like, and is excellent in cold flow characteristics. Therefore, it is suitably used for a rubber composition, and is particularly suitably used for a rubber composition for a tire.

<Polybutadiene according to the first aspect of the present invention> The polybutadiene according to the first aspect of the present invention has a viscosity of 5% toluene solution (Tcp) and a Mohs viscosity at 100 ° C measured at 25 ° C ( The ratio of ML _{1 + 4} ) (Tcp/ML _{1 + 4} ) is 1.3 or more and 5.0 or less, the molecular weight distribution (Mw/Mn) is 2.0 or more and less than 4, and the cold flow rate (CF) is 5.5 mg/min or less.

As mentioned above, in terms of the linearity index, the ratio of the 5% toluene solution viscosity (Tcp) measured at 25 ° C to the Mohs viscosity (ML _{1 + 4} ) at 100 ° C was previously used. Tcp/ML _{1 + 4} , the larger the Tcp/ML _{1 + 4} , it is considered that the branching degree is small and the linearity is large. The polybutadiene of the first aspect of the present invention is an unmodified unmodified polybutadiene, but the Tcp/ML _{1 + 4} is larger than 1.3 and the cold flow rate (CF) is 5.5 mg/ Min below the small. Such a polybutadiene is conventionally available, and can be obtained by polymerization using a specific catalyst as will be described later.

The polybutadiene of the first aspect of the present invention has a Tcp/ML _{1 + 4} of 1.3 or more, preferably 1.5 or more, and particularly preferably 1.7 or more. Further, the polybutadiene of the first aspect of the present invention has a Tcp/ML _{1 + 4} of 5.0 or less, preferably 4.0 or less, more preferably 3.5 or less, and still more preferably 3.0 or less.

The cold flow rate (CF) of the polybutadiene according to the first aspect of the present invention is 5.5 mg/min or less, preferably 5.0 mg/min or less, more preferably 4.8 mg/min or less, and particularly preferably 4.6 mg/min. Min below.

The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polybutadiene according to the first aspect of the present invention, that is, the molecular weight distribution (Mw/Mn) is 2.0 or more, preferably 2.3 or more, and particularly preferably 2.5 or more. Further, the molecular weight distribution (Mw/Mn) of the polybutadiene according to the first aspect of the present invention is less than 4, preferably 3.8 or less, more preferably 3.5 or less, and still more preferably 3.2 or less.

The polybutadiene according to the first aspect of the present invention which is in accordance with the above physical properties has excellent characteristics such as abrasion resistance, low heat build-up property, rebound elasticity, and the like, and has excellent cold flow characteristics, that is, storage (storage) stability. Sex is also excellent.

The polybutadiene of the first aspect of the present invention preferably has a Mohs viscosity (ML _{1 + 4} ) at 100 ° C of 25 or more and 60 or less. The ML _{1 + 4 of the} polybutadiene according to the first aspect of the present invention is more preferably 30 or more, and particularly preferably 35 or more. Further, the ML _{1 + 4 of the} polybutadiene according to the first aspect of the present invention is more preferably 57 or less, and particularly preferably 55 or less.

The number average molecular weight (Mn) of the polybutadiene according to the first aspect of the present invention is not particularly limited, but is preferably 50,000 or more and 300,000 or less, more preferably 100,000 or more and 250,000 or less. The weight average molecular weight (Mw) of the polybutadiene according to the first aspect of the present invention is not particularly limited, but is preferably 300,000 or more and 700,000 or less, and more preferably 350,000 to 600,000.

The polybutadiene according to the first aspect of the present invention preferably has a cis-1,4-structure content of 90% or more. The cis-1,4-structure content of the polybutadiene according to the first aspect of the present invention is more preferably 92% or more, still more preferably 93% or more, still more preferably 94% or more, still more preferably 94.5. More than %, especially preferably 95% or more or more than 95%.

Further, the intrinsic viscosity (intrinsic viscosity measured at 25 ° C in toluene) [η] of the polybutadiene according to the first aspect of the present invention is not particularly limited, but is preferably 0.1 to 10, more preferably 1 to 7. , especially good for control at 1.2~5.

The polybutadiene according to the first aspect of the present invention may be a copolymer, and a small amount (for example, an amount of 10 mol% or less) of isoprene or 1,3 may be used in addition to the butadiene monomer. -pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, 2,4-hexyl a conjugated diene such as a diene, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, etc. a cyclic monoolefin such as a cyclic monoolefin, cyclopentene, cyclohexene or norbornene, and/or an aromatic vinyl compound such as styrene or α-methylstyrene, dicyclopentadiene or 5- Other monomers such as ethylene-2-norbornene and 1,5-hexadiene are copolymerized by other monomers such as non-conjugated diene.

The polybutadiene according to the first aspect of the present invention has excellent properties and is excellent in storage (storage) stability, and is suitable for use in various applications, and is suitably used, for example, in rubber applications, particularly rubber compositions for tires. The rubber composition for a tire comprising polybutadiene according to the first aspect of the present invention is particularly suitable for a low fuel cost tire. The rubber composition of the polybutadiene according to the first aspect of the present invention is also suitably used for a rubber belt, a rubber crawler, a golf ball, a shoe, a fender, and the like.

<Polybutadiene according to the second aspect of the present invention> The polybutadiene according to the second aspect of the present invention, the butadiene monomer unit obtained by ¹³ C-NMR measurement of hydrogenated polybutadiene The number of 10,000 long chain branch points (however, the long chain branch point means that the branching chain of 6 or more carbon atoms formed by two or more butadiene units is bonded to the branch point of the main chain) is 9 or less. Concentration conversion G", concentration conversion G from the measurement of the angular dependence of the storage elastic coefficient G' and the loss elastic coefficient G'' from the 50% by mass solution of polybutadiene and 10% by mass solution 'Y ratio of Y=G'/C ² (but C represents the solution concentration) as defined by X=G''/C ² = 20,000 Pa [Y _(50%) / Y _(10%) (only Y _(50%) is obtained by measuring 50% by mass of a liquid paraffin solution, and Y _(10%) is obtained by measuring 10% by mass of a liquid paraffin solution.)] is more than 2.

Here, Y _(50%) / Y _(10%) is an index of molecular linearity. When the polybutadiene has a small branching degree and a high linearity, the difference between Y _(50%) and Y _(10%) is small, that is, Y _(50%) / Y _{(10%) is} close to 1, and the branching degree is large. If the linearity is low, Y _(50%) / Y _(10%) increases.

In the second aspect of the present invention, Y _(50%) / Y _{(10%) is} more than 2, and on the other hand, the number of long-chain branching points is less than 9 or less. Such a polybutadiene is conventionally obtained, and can be obtained by polymerization using a specific catalyst as will be described later.

Further, the polybutadiene according to the second aspect of the present invention which is in accordance with the above physical properties has excellent properties such as abrasion resistance, low heat build-up property, rebound elasticity, and the like, and is excellent in cold flow characteristics, that is, storage ( Storage) Stability is also excellent.

The number of long chain branch points per 10,000 of the butadiene monomer units determined by ¹³ C-NMR measurement of the polybutadiene according to the second aspect of the present invention is 9 or less, preferably 8 or less. In addition, the number of long-chain branching points per 10,000 of the butadiene monomer units obtained by ¹³ C-NMR measurement of the polybutadiene of the second aspect of the present invention is not particularly limited, and is preferably 2 or more. The method for obtaining the number of long-chain branch points is specifically described in the embodiment.

The concentration dependence of the angular dependence of the storage elastic modulus G′ and the loss elastic modulus G′′ of the 50% by mass solution of the polybutadiene of the polybutadiene according to the second aspect of the present invention and the 10% by mass solution Convert G'', the concentration conversion G' becomes Y=G'/C ² = 20,000Pa, Y=G'/C ² (but C represents the solution concentration), the ratio of Y is defined as [Y _(50%) / Y _(10%) ] is more than 2, preferably 2.3 or more, and particularly preferably 2.5 or more. Further, Y _(50%) / Y _{(10%) of the} polybutadiene according to the second aspect of the present invention is not particularly limited, but is preferably 4.5 or less, more preferably 4.0 or less, and still more preferably 3.8 or less. The method for obtaining Y _(50%) / Y _(10%) is specifically described in the examples.

The cold flow rate (CF) of the polybutadiene according to the second aspect of the present invention is not particularly limited, but is preferably 5.5 mg/min or less, more preferably 5.0 mg/min or less, still more preferably 4.8 mg/min or less. It is especially preferred to be 4.6 mg/min or less.

The number average molecular weight (Mn) of the polybutadiene according to the second aspect of the present invention is not particularly limited, but is preferably 50,000 or more and 300,000 or less, more preferably 100,000 or more and 250,000 or less. The weight average molecular weight (Mw) of the polybutadiene according to the second aspect of the present invention is not particularly limited, but is preferably 300,000 or more and 700,000 or less, and more preferably 350,000 to 600,000.

The molecular weight distribution (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polybutadiene according to the second aspect of the present invention is preferably 2.0 or more, more preferably 2.3 or more, and particularly preferably 2.5 or more. Further, the molecular weight distribution (Mw/Mn) of the polybutadiene of the second aspect of the present invention is preferably less than 4, more preferably 3.8 or less, still more preferably 3.5 or less, still more preferably 3.2 or less.

The Mohs' viscosity (ML _{1 + 4} ) of the polybutadiene of the second aspect of the present invention at 100 ° C is preferably 25 or more and 60 or less. The ML _{1 + 4 of the} polybutadiene according to the second aspect of the present invention is more preferably 30 or more, and particularly preferably 35 or more. Further, the ML _{1 + 4 of the} polybutadiene according to the second aspect of the present invention is more preferably 57 or less, and particularly preferably 55 or less.

The Tcp/ML _{1 + 4 of the} polybutadiene according to the second aspect of the present invention is preferably 1.3 or more, more preferably 1.5 or more, and still more preferably 1.7 or more. Further, the Tcp/ML _{1 + 4 of the} polybutadiene according to the second aspect of the present invention is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and still more preferably 3.0 or less.

The poly-butadiene of the second aspect of the present invention preferably has a cis-1,4-structure content of 90% or more. The cis-1,4-structure content of the polybutadiene according to the second aspect of the present invention is more preferably 92% or more, still more preferably 93% or more, still more preferably 94% or more, still more preferably 94.5%. Above, it is particularly preferably 95% or more or more than 95%.

Further, the intrinsic viscosity (intrinsic viscosity measured at 25 ° C in toluene) [η] of the second aspect of the present invention is not particularly limited, and is preferably controlled to 0.1 to 10, more preferably 1 ~7, especially good is 1.2~5.

The polybutadiene of the second aspect of the present invention may also be a copolymer, and in addition to the butadiene monomer, a small amount (for example, an amount of 10 mol% or less) of isoprene or 1,3- may be used. Pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, 2,4-hexane Non-cyclic conjugated diene such as olefin, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene a cyclic monoolefin such as a monoolefin, a cyclopentene, a cyclohexene or a decene, and/or an aromatic vinyl compound such as styrene or α-methylstyrene, dicyclopentadiene or 5-a Another monomer such as a non-conjugated diene such as ethyl-2-nordecene or 1,5-hexadiene is copolymerized.

The polybutadiene according to the second aspect of the present invention has excellent properties and is excellent in storage (storage) stability, and is suitably used in various applications, and is suitably used, for example, in rubber applications, particularly rubber compositions for tires. A rubber composition for a tire comprising a polybutadiene according to a second aspect of the present invention is particularly suitable for a tire having a low fuel cost. The rubber composition of the polybutadiene including the second aspect of the present invention is also suitably used for a rubber belt, a rubber crawler, a golf ball, a shoe, a fender, and the like.

<Polybutadiene of the third aspect of the invention> The polybutadiene of the third aspect of the invention, the butadiene monomer unit obtained by ¹³ C-NMR measurement of hydrogenated polybutadiene The number of 10,000 long chain branch points (only the long chain branch point means that the branching chain of 6 or more carbon atoms formed by two or more butadiene units is bonded to the branch point of the main chain.) is 9 or less, cold The flow velocity (CF) was 5.5 mg/min or less.

As described above, as a parameter of molecular linearity, the ratio of the viscosity of 5% toluene solution (Tcp) measured at 25 ° C to the Mohs viscosity (ML _{1 + 4} ) at 100 ° C is Tcp/ML _{1 + 4} , However, it is considered that Tcp/ML _{1 + 4 is} large, that is, polybutadiene having a small branching degree and high linearity tends to exhibit a relatively high cold flow.

In the polybutadiene according to the third aspect of the present invention, the number of long-chain branching points is less than 9 and the cold flow rate (CF) is as small as 5.5 mg/min or less. Such a polybutadiene has not been conventionally used, and can be obtained by polymerization using a specific catalyst as will be described later.

Further, the polybutadiene according to the third aspect of the present invention which is in accordance with the above physical properties has excellent properties such as abrasion resistance, low heat build-up, and rebound elasticity, and is excellent in cold flow characteristics, that is, storage (storage) ) Stability is also excellent.

The number of long chain branch points per 10,000 of the butadiene monomer units determined by ¹³ C-NMR measurement of the polybutadiene of the third aspect of the present invention is 9 or less, preferably 8 or less. Further, the number of long-chain branching points per 10,000 of the butadiene monomer units obtained by ¹³ C-NMR measurement of the polybutadiene of the third aspect of the present invention is not particularly limited, and is preferably 2 or more.

The cold flow rate (CF) of the polybutadiene according to the third aspect of the present invention is 5.5 mg/min or less, preferably 5.0 mg/min or less, more preferably 4.8 mg/min or less, and particularly preferably 4.6 mg/min. Min below.

The number average molecular weight (Mn) of the polybutadiene according to the third aspect of the present invention is not particularly limited, but is preferably 50,000 or more and 300,000 or less, more preferably 100,000 or more and 250,000 or less. The weight average molecular weight (Mw) of the polybutadiene according to the third aspect of the present invention is not particularly limited, but is preferably 300,000 or more and 700,000 or less, and more preferably 350,000 to 600,000.

The molecular weight distribution (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polybutadiene according to the third aspect of the present invention is preferably 2.0 or more, more preferably 2.3 or more, and particularly preferably 2.5 or more. Further, the molecular weight distribution (Mw/Mn) of the polybutadiene according to the third aspect of the present invention is preferably less than 4, more preferably 3.8 or less, still more preferably 3.5 or less, still more preferably 3.2 or less.

The polybutadiene of the third aspect of the present invention preferably has a Mohs viscosity (ML _{1 + 4} ) at 100 ° C of 25 or more and 60 or less. The ML _{1 + 4 of the} polybutadiene according to the third aspect of the present invention is more preferably 30 or more, and particularly preferably 35 or more. Further, the ML _{1 + 4 of the} polybutadiene according to the third aspect of the present invention is more preferably 57 or less, and particularly preferably 55 or less.

The Tcp/ML _{1 + 4 of the} polybutadiene according to the third aspect of the present invention is preferably 1.3 or more, more preferably 1.5 or more, and still more preferably 1.7 or more. Further, the Tcp/ML _{1 + 4 of the} polybutadiene according to the third aspect of the present invention is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and still more preferably 3.0 or less.

The polybutadiene of the third aspect of the present invention preferably has a cis-1,4-structure content of 90% or more. The cis-1,4-structure content of the polybutadiene according to the third aspect of the present invention is more preferably 92% or more, still more preferably 93% or more, still more preferably 94% or more, still more preferably 94.5% or more. , especially better than 95% or more than 95%.

Further, the intrinsic viscosity (intrinsic viscosity measured at 25 ° C in toluene) [η] of the polybutadiene according to the third aspect of the present invention is not particularly limited, and is preferably controlled to 0.1 to 10, more preferably 1 ~7, especially good is 1.2~5.

The polybutadiene of the third aspect of the present invention may also be a copolymer, and in addition to the butadiene monomer, a small amount (for example, an amount of 10 mol% or less) of isoprene or 1,3- may be used. Pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, 2,4-hexane Non-cyclic conjugated diene such as olefin, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene a cyclic monoolefin such as a monoolefin, a cyclopentene, a cyclohexene or a decene, and/or an aromatic vinyl compound such as styrene or α-methylstyrene, dicyclopentadiene or 5-a Other monomers such as a non-conjugated diene such as ethyl-2-northene or 1,5-hexadiene are copolymerized.

The polybutadiene according to the third aspect of the present invention has excellent properties and is excellent in storage (storage) stability, and is suitably used in various applications, and is suitably used, for example, in rubber applications, particularly rubber compositions for tires. The rubber composition for a tire comprising the polybutadiene of the third aspect of the invention is particularly suitable for a low fuel cost tire. The rubber composition of polybutadiene including the third aspect of the present invention is also suitably used for rubber belts, rubber crawlers, golf balls, footwear, fenders and the like.

<Polybutadiene of the fourth aspect of the invention> The polybutadiene of the fourth aspect of the invention has a viscosity of 5% toluene solution (Tcp) measured at 25 ° C and a Mohs viscosity at 100 ° C ( The ratio of ML _{1 + 4} ) (Tcp/ML _{1 + 4} ) is 1.3 or more, and the storage elastic modulus G′ and the loss elastic modulus G′′ of the 50% by mass solution of the flowable paraffin from the polybutadiene and the 10% by mass solution. Determination of the angular frequency dependence is determined by the concentration conversion G'', and the concentration conversion G' is defined as Y=G''/C ² = 20,000 Pa when Y=G'/C ² (only C is the solution concentration) Y ratio [Y _(50%) / Y _(10%) (only Y _(50%) is obtained from the measurement of a 50% by mass solution of flowing paraffin, Y _(10%) is _{10% by} mass of paraffin wax The determination of the solution is more than 2).

Here, Y _(50%) / Y _(10%) is an index of molecular linearity. When the polybutadiene has a small branching degree and a high linearity, the difference between Y _(50%) and Y _(10%) is small, that is, Y _(50%) / Y _{(10%) is} close to 1, and the branching degree is large. If the linearity is low, Y _(50%) / Y _(10%) increases.

On the other hand, as described above, the viscosity of the 5% toluene solution (Tcp) measured at 25 ° C and the Mohs viscosity at 100 ° C (ML _{1 + 4} ) are used as indicators of molecular linearity. The ratio Tcp/ML _{1 + 4} is considered to be small and the linearity is high as the Tcp/ML _{1 + 4 is} larger.

In the fourth aspect of the present invention, the polybutadiene has a Tcp/ML _{1 + 4} of 1.3 or more (i.e., represents a small branching degree and a high linearity), and on the other hand, Y _(50%) / Y. _{(10%) is} greater than 2 (that is, it represents a large branching degree and a low linearity). Such a polybutadiene is conventionally obtained, and can be obtained by polymerization using a specific catalyst as will be described later.

Further, the polybutadiene according to the fourth aspect of the present invention which is in accordance with the above physical properties has excellent characteristics such as abrasion resistance, low heat build-up property, rebound elasticity, and the like, and at the same time, excellent cold flow characteristics, that is, storage ( Storage) Stability is also excellent.

The polybutadiene of the fourth aspect of the present invention has a Tcp/ML _{1 + 4} of 1.3 or more, preferably 1.5 or more, and particularly preferably 1.7 or more. Further, the Tcp/ML _{1 + 4 of the} polybutadiene according to the fourth aspect of the present invention is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, still more preferably 3.0 or less.

The concentration dependence of the angular dependence of the storage elastic modulus G′ and the loss elastic modulus G′′ of the 50% by mass solution of the polybutadiene of the polybutadiene of the fourth aspect of the present invention and the 10% by mass solution Conversion G'', concentration conversion G' becomes Y=G''/C ² = 20,000Pa when Y=G'/C ² (but C represents the solution concentration) The ratio of Y is defined as [Y _(50%) / Y _(10%) ] is more than 2, preferably 2.3 or more, and particularly preferably 2.5 or more. Further, Y _(50%) / Y _{(10%) of the} polybutadiene according to the fourth aspect of the present invention is not particularly limited, but is preferably 4.5 or less, more preferably 4.0 or less, and still more preferably 3.8 or less.

The cold flow rate (CF) of the polybutadiene according to the fourth aspect of the present invention is not particularly limited, but is preferably 5.5 mg/min or less, more preferably 5.0 mg/min or less, still more preferably 4.8 mg/min or less. More preferably, it is 4.6 mg/min or less.

The number average molecular weight (Mn) of the polybutadiene according to the fourth aspect of the present invention is not particularly limited, but is preferably 50,000 or more and 300,000 or less, more preferably 100,000 or more and 250,000 or less. The weight average molecular weight (Mw) of the polybutadiene according to the fourth aspect of the present invention is not particularly limited, but is preferably from 300,000 to 700,000, more preferably from 350,000 to 600,000.

The molecular weight distribution (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polybutadiene according to the fourth aspect of the present invention is preferably 2.0 or more, more preferably 2.3 or more, and particularly preferably 2.5 or more. Further, the molecular weight distribution (Mw/Mn) of the polybutadiene according to the fourth aspect of the present invention is preferably less than 4, more preferably 3.8 or less, still more preferably 3.5 or less, still more preferably 3.2 or less.

The Mohs' viscosity (ML _{1 + 4} ) of the polybutadiene of the fourth aspect of the present invention at 100 ° C is preferably 25 or more and 60 or less. The ML _{1 + 4 of the} polybutadiene of the fourth aspect of the invention is more preferably 30 or more, and particularly preferably 35 or more. Further, the ML _{1 + 4 of the} polybutadiene according to the fourth aspect of the present invention is more preferably 57 or less, still more preferably 55 or less.

The cis-1,4-structure content of the polybutadiene of the fourth aspect of the present invention is preferably 90% or more. The cis-1,4-structure content of the polybutadiene of the fourth aspect of the invention is more preferably 92% or more, still more preferably 93% or more, still more preferably 94% or more, still more preferably 94.5% or more. , especially better than 95% or more than 95%.

Further, the intrinsic viscosity (intrinsic viscosity measured at 25 ° C in toluene) [η] of the fourth aspect of the present invention is not particularly limited, and is preferably controlled to 0.1 to 10, more preferably 1 ~7, especially good is 1.2~5.

The polybutadiene of the fourth aspect of the present invention may also be a copolymer, and a small amount (for example, an amount of 10 mol% or less) other than the butadiene monomer may be used, and isoprene or 1,3-pentane may be used. Diene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, 2,4-hexadiene Non-cyclic such as conjugated diene, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene a cyclic monoolefin such as a monoolefin, a cyclopentene, a cyclohexene or a norbornene, and/or an aromatic vinyl compound such as styrene or α-methylstyrene, dicyclopentadiene or 5-Azine Other monomers such as non-2-conjugated diene such as quinolone and 1,5-hexadiene are copolymerized.

The polybutadiene according to the fourth aspect of the present invention has excellent properties and is excellent in storage (storage) stability, and is suitably used in various applications, and is suitably used, for example, in rubber applications, particularly rubber compositions for tires. The rubber composition for tires including the polybutadiene of the fourth aspect of the present invention is particularly suitable for use in a tire of low fuel cost. The rubber composition of polybutadiene including the fourth aspect of the present invention is also suitable for use in rubber belts, rubber crawlers, golf balls, footwear, fenders and the like.

<Method for Producing Polybutadiene> The first aspect, the second aspect, the third aspect, and the fourth aspect of the present invention are polybutadiene (hereinafter referred to as "polybutadiene of the present invention" For example, it can be manufactured in the following manner. However, the polybutadiene of the present invention is not limited to the manufacturer according to the following production method.

The catalyst for polymerization of polybutadiene is preferably a non-metallocene type metal compound (A) represented by the following formula (1), an ionic compound composed of a non-coordinating anion and a cation, or an aluminoxane (B). And an organometallic compound (C) selected from the group consisting of elements of Groups 2, 12, and 13 of the periodic table.

【化1】 (R ¹ , R ² , and R ³ each represent a hydrogen or a substituent having 1 to 12 carbon atoms. O represents an oxygen atom, and M represents Gd (釓 atom), Tb (鋱 atom), Dy (镝 atom), Ho ( Helium atom, Er (铒 atom), or Tm (銩 atom).)

Specific examples of the substituent having 1 to 12 carbon atoms of R ¹ to R ^{3 in} the formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, second butyl group and the like. Butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethyl a saturated hydrocarbon group such as propyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, decyl, decyl, undecyl, and dodecyl, vinyl, 1-propenyl, and allylic An alicyclic hydrocarbon group such as an unsaturated hydrocarbon group such as a group, a cyclohexyl group, a methylcyclohexyl group or an ethylcyclohexyl group; and an aromatic hydrocarbon group such as a phenyl group, a benzyl group, a tolylmethyl group or a phenethyl group; Further, among these, a substituent such as a hydroxyl group, a carboxyl group, a carbonylmethoxy group, a carbonylethoxy group, a decylamino group, an amine group, an alkoxy group, or a phenoxy group may be contained at any position. Among them, a saturated hydrocarbon group having 1 to 12 carbon atoms is preferred, and a saturated hydrocarbon group having 1 to 6 carbon atoms is preferred.

R ¹ to R ³ and R ^{2 of the} formula (1) are preferably hydrogen or a substituent having a carbon number of 1 to 12 (preferably a saturated hydrocarbon group), and R ¹ and R ³ are a substituent having 1 to 12 carbon atoms. Preferably, it is a saturated hydrocarbon group). In particular, R ² is hydrogen or a substituent having 1 to 6 carbon atoms (preferably a saturated hydrocarbon group), and R ¹ and R ³ are preferably a substituent having 1 to 6 carbon atoms (preferably a saturated hydrocarbon group).

M is a non-metallocene type metal compound (A) of the formula (1) of Gd (deuterium atom), and specific examples thereof include ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ) 釓, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng (3 ,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2,4 -pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedione acid) hydrazine, and the like.

Among them, ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate) ruthenium is preferred. , ginseng (2,4-pentanedionate) hydrazine and the like. More preferably, for example, ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) or ruthenium (2,6-dimethyl-3,5-heptanedionate) ruthenium.

M is a non-metallocene type metal compound (A) of the formula (1) of Tb (deuterium atom), and specific examples thereof include ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ) 鋱, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng (3 ,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2,4 -pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedione acid) hydrazine, and the like.

Among them, preferred are, for example, stilbene (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate)鋱, ginseng (2,4-pentanedionate) oxime and the like. More preferably, for example, ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) or ruthenium (2,6-dimethyl-3,5-heptanedionate) ruthenium.

M is a non-metallocene type metal compound (A) of the formula (1) of Dy (deuterium atom), and specific examples thereof include: (2,2,6,6-tetramethyl-3,5-heptanedione) Acid, hydrazine, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng 3,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2, 4-pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedionate) hydrazine, and the like.

Among them, preferred are, for example, stilbene (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate)镝, ginseng (2,4-pentanedionate) oxime and the like. More preferably, for example, ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) or ruthenium (2,6-dimethyl-3,5-heptanedionate) ruthenium.

M is a non-metallocene type metal compound (A) of the formula (1) of Ho (deuterium atom), and specific examples thereof include ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ) 鈥, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng (3 ,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2,4 -pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedione acid) hydrazine, and the like.

Among them, preferred are, for example, stilbene (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate)鈥, ginseng (2,4-pentanedionate) oxime and the like. More preferably, for example, ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate) ruthenium .

M is a non-metallocene type metal compound (A) of the formula (1) of Er (deuterium atom), and specific examples thereof include: (2,2,6,6-tetramethyl-3,5-heptanedione) Acid, hydrazine, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng 3,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2, 4-pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedionate) hydrazine, and the like.

Among them, preferred are, for example, stilbene (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate)铒, ginseng (2,4-pentanedionate) oxime and the like. More preferably, for example, ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) or ruthenium (2,6-dimethyl-3,5-heptanedionate) ruthenium.

M is a non-metallocene type metal compound (A) of the formula (1) of Tm (deuterium atom), and specific examples thereof include: (2,2,6,6-tetramethyl-3,5-heptanedione) Acid, hydrazine, ginseng (2,6,6-trimethyl-3,5-heptanedionate) hydrazine, ginseng (2,6-dimethyl-3,5-heptanedionate) hydrazine, ginseng 3,5-heptanedionate) hydrazine, ginseng (2,4-pentanedionate) hydrazine, ginseng (2,4-hexanedione acid) hydrazine, ginseng (1,5-dicyclopentyl-2, 4-pentanedione acid) hydrazine, ginseng (1,5-dicyclohexyl-2,4-pentanedionate) hydrazine, and the like.

Among them, preferred are, for example, stilbene (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium, ginseng (2,6-dimethyl-3,5-heptanedionate)銩, ginseng (2,4-pentanedionate) oxime and the like. More preferably, for example, ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) or ruthenium (2,6-dimethyl-3,5-heptanedionate) ruthenium.

The non-metallocene type metal compound (A) may be used singly or in combination of two or more.

In the ionic compound composed of a non-coordinating anion and a cation as the component (B), examples of the non-coordinating anion include tetrakis(phenyl)borate, tetrakis(fluorophenyl)borate, and ruthenium ( Difluorophenyl)borate, lanthanum trifluorophenyl)borate, ruthenium (tetrafluorophenyl)borate, ruthenium (pentafluorophenyl)borate, ruthenium (3,5-bistrifluoromethylbenzene) Base) borate, bismuth (tetrafluoromethylphenyl) borate, tetrakis(tolyl)borate, tetrakis(dimethylphenyl)borate, triphenyl(pentafluorophenyl)borate, pentoxide Phenyl)(phenyl)borate, tridehyde-7,8-dicarbaundecaborate, tetrafluoroborate, hexafluorophosphate, and the like.

On the other hand, examples of the cation include a carbocation, an oxonium, an ammonium cation, a phosphonium cation, a cycloheptatrienyl cation, a ferrocenium cation, and the like.

Specific examples of the carbocation include a trisubstituted carbocation such as a triphenylcarbocarboxylate or a trisubstituted phenylcarbocation. Specific examples of the trisubstituted phenyl carbocation include a tri(methylphenyl) carbocation and a tris(dimethylphenyl) carbocation.

Specific examples of the ammonium cation include a trialkylammonium cation such as a trimethylammonium cation, a triethylammonium cation, a tripropylammonium cation, a tri(n-butyl)ammonium cation, or a tri(isobutyl)ammonium cation. N,N-dimethylanilinium cation, N,N-diethylanilinium cation, N,N-2,4,6-pentamethylaniline cation, etc. N,N-dialkylaniline cation, di(isopropyl a dialkylammonium cation such as an ammonium cation or a dicyclohexylammonium cation.

Specific examples of the phosphonium cation include a triphenylphosphonium cation, a tetraphenylphosphonium cation, a tris(methylphenyl)phosphonium cation, a tetrakis(methylphenyl)phosphonium cation, and a tris(dimethylphenyl)phosphonium cation. An aryl phosphonium cation such as a tetrakis(dimethylphenyl)phosphonium cation.

The ionic compound (B) is preferably arbitrarily selected and combined from the above-described non-coordinating anions and cations.

Among them, the ionic compound (B) is preferably a boron-containing compound, among which, particularly triphenylcarbenium quinone (pentafluorophenyl)borate, triphenylcarbenium sulfonate (fluorophenyl)borate, bismuth (five) Fluorophenyl)boronic acid N,N-dimethylaniline, decyl (pentafluorophenyl)boronic acid 1,1'-dimethylferrocene or the like is preferred. The ionic compound (B) may be used singly or in combination of two or more.

Further, an aluminoxane may be used instead of the ionic compound composed of a non-coordinating anion and a cation of the component (B). The aluminoxane is obtained by contacting an organoaluminum compound and a condensing agent, and examples thereof include a formula (-Al(R')O-)n (R' is a hydrocarbon group having 1 to 10 carbon atoms, and a part thereof is halogen atom and/or Or alkoxy substituted. n is a degree of polymerization, and is 5 or more, preferably 10 or more.) A chain aluminoxane or a cyclic aluminoxane. R' may, for example, be a methyl group, an ethyl group, a propyl group or an isobutyl group, and a methyl group is preferred. An organoaluminum compound which can be used as a raw material of aluminoxane, for example, trialkylaluminum such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, and a mixture thereof. Among these, aluminoxane which uses a mixture of trimethylaluminum and triisobutylaluminum as a raw material is preferably used.

The condensing agent used for the production of the aluminoxane is exemplified by water, and examples thereof include any of the condensation reaction of the organoaluminum compound, for example, adsorbed water or a diol such as an inorganic substance.

As the organometallic compound of the component (C) selected from the elements of Groups 2, 12, and 13 of the periodic table, for example, organomagnesium, organozinc, or organoaluminum can be used. Among these compounds, a dialkyl magnesium; an alkyl magnesium halide such as an alkyl magnesium chloride or an alkyl magnesium bromide; a dialkyl zinc; a trialkyl aluminum; a dialkyl aluminum chloride; a dialkyl aluminum bromide; An organoaluminum halide compound such as an alkyl sesquihalahalide, an alkyl sesquichloride or an alkyl aluminum dichloride; or a hydrogenated organoaluminum compound such as a dialkylaluminum hydride is preferred.

Specific examples of the compound include methyl magnesium chloride, ethyl magnesium chloride, butyl magnesium chloride, hexyl magnesium chloride, octyl magnesium chloride, ethyl magnesium bromide, butyl magnesium bromide, butyl magnesium iodide, and hexyl magnesium iodide. Magnesium halide.

Further, examples thereof include dialkylmagnesium such as dimethylmagnesium, diethylmagnesium, dibutylmagnesium, dihexylmagnesium, dioctylmagnesium, ethylbutylmagnesium or ethylhexylmagnesium.

Further, examples thereof include dialkyl zinc such as dimethyl zinc, diethyl zinc, diisobutyl zinc, dihexyl zinc, dioctyl zinc, and dimercapto zinc.

Further, a trialkyl aluminum such as trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctyl aluminum or tridecyl aluminum may be mentioned.

Further, examples thereof include dialkyl aluminum chloride such as dimethyl aluminum chloride and diethyl aluminum chloride, and an organic aluminum halogen compound such as ethyl chloride or ethyl aluminum dichloride, and diethyl hydrogenation. A hydrogenated organoaluminum compound such as aluminum, diisobutylaluminum hydride or ethylaluminum sesquihydride.

The organometallic compound (C) which is an element selected from Group 2, Group 12, and Group 13 of the periodic table may be used singly or in combination of two or more.

Among them, an organometallic compound of a group 13 element is preferable, and an organoaluminum is preferred, trimethylaluminum, triethylaluminum, triisobutylaluminum or the like. Particularly preferred is triethyl aluminum. (A) component (non-metallocene type metal compound), (B) component (ionic compound composed of non-coordinating anion and cation) and (C) component of the catalyst for polymerization of polybutadiene of the present invention ( The ratio of the organometallic compound selected from the elements of Groups 2, 12, and 13 of the periodic table is not particularly limited, and the amount of the component (B) is preferably 0.5 to 10 moles per 1 mole of the component (A). 1~5 Moore is especially good. The amount of the component (C) is preferably from 10 to 10,000 m per 1 mol of the component (A), and preferably from 50 to 7,000 m.

In the present invention, the polymerization is carried out using a catalyst having the components (A), (B) and (C), but the molecular weight modifier of the obtained polybutadiene may be added to the extent that the effects of the present invention are not impaired. .

As the molecular weight modifier, a compound selected from hydrogen, a metal hydride compound, and a hydrogenated organometallic compound can be used.

Examples of the hydrogenated metal compound include lithium hydride, sodium hydride, potassium hydride, magnesium hydride, calcium hydride, borane, aluminum hydride, gallium hydride, decane, decane, lithium borohydride, sodium borohydride, lithium aluminum hydride, sodium hydride, and the like. .

Further, examples of the hydrogenated organometallic compound include alkylboranes such as methylborane, ethylborane, propylborane, butylborane, and phenylborane; dimethylborane and diethylborane; Dialkylborane such as dipropylborane, dibutylborane or diphenylborane; methyl aluminum dihydride, ethyl aluminum dihydride, propyl aluminum dihydride, butyl aluminum dihydride, benzene Alkyl aluminum hydride such as aluminum dihydrogen hydride; dimethyl aluminum hydride, diethyl aluminum hydride, dipropyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, diphenyl aluminum hydride, etc. Alkyl aluminum hydride; methyl decane, ethyl decane, propyl decane, butyl decane, phenyl decane, dimethyl decane, diethyl decane, dipropyl decane, dibutyl decane, diphenyl decane, a decane such as trimethyl decane, triethyl decane, tripropyl decane, tributyl decane or triphenyl decane; methyl decane, ethyl decane, propyl decane, butyl decane, phenyl Decane, dimethyl decane, diethyl decane, dipropyl decane, dibutyl decane, diphenyl decane, trimethyl decane, triethyl decane, tripropyl Alkoxy, tributyl germane, triphenyl germane and the like germane and the like.

Among these, diisobutylaluminum hydride and diethylaluminum hydride are preferred.

In the present invention, each catalyst component may be used by being carried on an inorganic compound or an organic polymer compound.

In the method for producing polybutadiene of the present invention, the order of addition of the above-mentioned catalyst components [(A), (B) and (C) components] is not particularly limited, and for example, it can be carried out in the following order.

(1) The component (C) is added to the passive organic solvent in the presence or absence of a monomer, and the component (A) and the component (B) are added in any order.

(2) Adding the component (C) in the presence or absence of a monomer in a passive organic solvent, and adding the above-mentioned molecular weight modifier, the component (A) and the component (B) are added in an arbitrary order.

(3) The component (B) is added in a passive organic solvent in the presence or absence of a monomer, and the component (C) and the molecular weight modifier are added in any order, and then the component (B) is added.

(4) The component (B) is added in a passive organic solvent in the presence or absence of a monomer, and the component (C) and the molecular weight modifier are added in any order, and then the component (A) is added.

(5) The (M) component is added to the passive organic solvent in the presence or absence of a monomer, and the component (A) and the component (B) are added in an arbitrary order, and then the molecular weight modifier is added.

Here, the monomer to be initially added may be a total amount or a part of the monomer.

As described above, the polybutadiene of the present invention may be copolymerized with a small amount of other monomers in addition to 1,3-butadiene. Examples of the monomer other than 1,3-butadiene which are raw materials include isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, and 2,3-dimethyl a conjugated diene such as butadiene, 2-methylpentadiene, 4-methylpentadiene or 2,4-hexadiene, ethylene, propylene, 1-butene, 2-butene, isobutylene, a cyclic monoolefin such as 1-pentene, 4-methyl-1-pentene, 1-hexene or 1-octene; a cyclic monoolefin such as cyclopentene, cyclohexene or norbornene; Or an aromatic vinyl compound such as styrene or α-methylstyrene, a non-conjugated diene such as dicyclopentadiene, 5-ethylidene-2-northene or 1,5-hexadiene. . These monomer components may be used alone or in combination of two or more.

The polymerization method is not particularly limited, and bulk polymerization such as 1,3-butadiene itself may be used as a polymerization solvent, or solution polymerization. Examples of the solvent for solution polymerization include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, benzene, toluene, xylene, ethylbenzene, and cumene. An aromatic hydrocarbon, an olefin compound, an olefin hydrocarbon such as cis-2-butene or trans-2-butene, or the like, wherein benzene, toluene, xylene, cyclohexane, or cis-2-butene is used. It is preferred to use a mixture with trans-2-butene. These solvents may be used alone or in combination of two or more.

The polymerization temperature is preferably in the range of -30 to 150 ° C, and the range of 0 to 100 ° C is more desirable, and the range of 10 to 80 ° C is particularly preferable. The polymerization time should be from 1 minute to 12 hours, more preferably from 3 minutes to 5 hours, and more preferably from 5 minutes to 1 hour. The amount of the catalyst for polymerization of polybutadiene of the present invention is not particularly limited, and the concentration of the component (A) (metal compound) is preferably from 1 to 100 μmol/L, more preferably from 2 to 50 μmol/L.

After the polymerization is carried out for a predetermined period of time, the inside of the polymerization tank is subjected to pressure release as needed, and post-treatment such as washing and drying steps is performed. In this way, the polybutadiene of the present invention can be obtained. In an embodiment, it is possible to exclude the polymerization of 1,3-butadiene using a catalyst comprising a non-metallocene type metal compound (A) represented by the above formula (1) wherein M is Gd (germanium atom). Polybutadiene.

<Rubber Composition (Rubber Composition for Tire)> The polybutadiene of the present invention is suitably used, for example, as a rubber composition, particularly a rubber composition for a tire.

The rubber composition of the present invention is characterized by comprising one or more of the polybutadienes of the present invention.

Specifically, the polybutadiene of the present invention may be used alone or blended with other synthetic rubber or natural rubber, and if necessary, oiled with a treatment oil, and then added with a filler such as carbon black and a sulfurizing agent. A conventional blending agent such as a vulcanization accelerator is used for vulcanization, and is used for rubber applications requiring mechanical properties and abrasion resistance of various industrial articles such as tires, hoses, and belts. Moreover, it can also be used as a modifier for plastic materials, for example, a modifier for impact-resistant polystyrene.

The rubber composition for a tire of the present invention is characterized in that one or more of the polybutadienes of the present invention are contained, and it is preferable to contain the polybutadiene of the present invention (hereinafter referred to as "polybutadiene (?)"). A diene polymer other than butadiene (hereinafter referred to as "diene polymer (β)") and a rubber reinforcing agent (hereinafter referred to as "rubber reinforcing agent (γ)") are preferred.

The rubber composition for a tire contains a rubber component (α) + (β) composed of a polydiene polymer (β) other than polybutadiene (α) and (α), and a rubber reinforcing agent (γ), and is relatively The content of the rubber reinforcing agent (γ) is preferably 30 to 80 parts by mass based on 100 parts by mass of the rubber component (α) + (β). That is, the blending amount of the rubber reinforcing agent (γ) is a rubber component (α)+(β) composed of a diene polymer (β) other than polybutadiene (α) and (α). 100 parts by mass is preferably 30 to 80 parts by mass, more preferably 40 to 70 parts by mass. Further, the mass ratio of the rubber component (α) + (β) of the rubber composition for a tire is preferably: polybutadiene (α) 90 to 5 parts by mass, and diene polymerization other than polybutadiene (α) The substance (β) is preferably 10 to 95 parts by mass.

The diene polymer (β) other than the polybutadiene used in the rubber composition for a tire of the present invention is preferably a vulcanizable rubber, and specific examples thereof include natural rubber, ethylene propylene diene rubber (EPDM), and nitrile. Rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR), polyisoprene, high cis polybutadiene rubber, low cis polybutadiene rubber (BR), styrene - Butadiene rubber (SBR), butyl rubber, chlorobutyl rubber, bromobutyl rubber, acrylonitrile-butadiene rubber, and the like. In the case of a rubber composition for a tire, the diene polymer (β) is preferably at least one of natural rubber, styrene-butadiene rubber, and polyisoprene. These rubbers may be used alone or in combination of two or more.

The rubber reinforcing agent (γ) used in the rubber composition for a tire of the present invention may, for example, be various kinds of carbon black, cerium oxide, activated calcium carbonate, ultrafine magnesium silicate, talc, mica or the like. The rubber reinforcing agent (γ) of the rubber composition for a tire is preferably at least one of carbon black and cerium oxide. The rubber reinforcing agents may be used singly or in combination of two or more.

In particular, when cerium oxide is used as the rubber reinforcing agent (γ), a decane coupling agent can also be used as an additive. The decane coupling agent used as an additive is an organic ruthenium compound represented by the general formula R ⁷ _n SiR ⁸ _4-n , and R ⁷ is selected from the group consisting of a vinyl group, a decyl group, an allyl group, an allyloxy group, and an amine. a group having 1 to 20 carbon atoms of a reactive group of a group, an epoxy group, a decyl group, a chloro group, an alkyl group, a phenyl group, a hydrogen group, a styrene group, a methacryl group, an acryl group, a ureido group or the like, and R ⁸ is A hydrolyzable group selected from the group consisting of a chloro group, an alkoxy group, an etecyloxy group, an isopropenyloxy group, an amine group, and the like, and n represents an integer of from 1 to 3. The R ^{7 of the} above decane coupling agent is preferably a vinyl group and/or a chlorine group.

The amount of the decane coupling agent to be added is preferably 0.2 to 20 parts by mass, more preferably 3 to 15 parts by mass, and particularly preferably 5 to 15 parts by mass, based on 100 parts by mass of the filler. If it is less than the above range, it may become a cause of coking. Moreover, if it is more than the said range, it may become the cause of the deterioration of a tensile characteristic and an extension.

The rubber reinforcing agent (γ) to which the rubber composition for a tire is blended may also be a fullerene as disclosed in JP-A-2006-131819. The fullerene may, for example, be a mixture of C60, C70, C60 and C70, and a derivative thereof. Fullerene derivatives include PCBM (phenyl C61 methyl butyrate), PCBNB (phenyl C61 butyrate), PCBIB (phenyl C61 butyrate), C70PCBM (phenyl C71 butyrate) )Wait. Further, fullerene hydroxide, oxidized fullerene, hydrogenated fullerene or the like can also be used.

The rubber composition for a tire of the present invention can be obtained by kneading each of the above components using a commonly used Banbury mixer, an open roll, a kneader, a biaxial kneader or the like.

In the rubber composition for a tire of the present invention, a blending agent such as a vulcanizing agent, a vulcanization aid, an anti-aging agent, a filler, a processing oil, a zinc oxide or a stearic acid, which is generally used in the rubber industry, may be kneaded as needed.

As the vulcanizing agent, a known sulfurizing agent such as sulfur, an organic peroxide, a resin vulcanizing agent, a metal oxide such as magnesium oxide, or the like can be used. The sulfur-adding agent is preferably 0.5 to 3 parts by mass based on 100 parts by mass of the rubber component (α) + (β).

As the vulcanization aid, a known vulcanization aid such as an aldehyde, an ammonia, an amine, an anthracene, a thiourea, a thiazole, a thiuram, a dithiocarbamate, or a xanthogen can be used. Xanthate) class and so on.

Examples of the antioxidant include an amine ketone system, an imidazole system, an amine system, a phenol system, a sulfur system, and a phosphorus system.

Examples of the filler include organic fillers such as cerium oxide, calcium carbonate, basic magnesium carbonate, clay, Litharge, and diatomaceous earth, and carbon black, recycled rubber, and powder rubber.

Any of an aromatic type, a naphthene type, and a paraffin type can also be used for a process oil. [Examples]

The invention will be further illustrated by the following examples and comparative examples. Further, the present invention is not limited to the following embodiments.

Measurement of catalyst activity, physical properties of polybutadiene, physical properties of the composition, and the like. The evaluation method is as follows.

Catalyst activity: The polymer yield per gram of the central metal of the catalyst used for the polymerization reaction, and the polymer yield per hour of the polymerization time (g). For example, when the catalyst is a ruthenium compound, the amount of the base metal per gram of the ruthenium compound used in the polymerization reaction is 1 mmol, and the polymer yield per hour is (g).

(Evaluation of polybutadiene) Microstructure: Implemented by infrared absorption spectrum analysis. From cis 734cm ^-1, trans 967cm ^-1, 910cm vinyl calculated from the absorption intensity ratio ^-1 microstructure.

The number average molecular weight (Mn) and the weight average molecular weight (Mw): using polystyrene as a standard material, tetrahydrofuran as a solvent, and GPC (manufactured by Shimadzu Corporation) at a temperature of 40 ° C, using the obtained molecular weight distribution The calibration curve obtained from the curve is calculated to determine the number average molecular weight and the weight average molecular weight.

Molecular weight distribution: The ratio of the weight average molecular weight Mw and the number average molecular weight Mn, Mw/Mn, determined by GPC using polystyrene as a standard substance was evaluated.

Mohs viscosity (ML _{1 + 4} , 100 ° C): According to JIS-K6300, using a Mohs viscometer manufactured by Shimadzu Corporation, after preheating at 100 ° C for 1 minute, measuring for 4 minutes, with Mohs viscosity of rubber Formal representation of (ML _{1 + 4} , 100 ° C).

Toluene solution viscosity (Tcp): After dissolving 2.28 g of polybutadiene in 50 ml of toluene, a standard solution for viscosity meter calibration (JIS-Z8809) was used as a standard solution, and a Cannon-Fenske viscometer No. 400 was used at 25 ° C. Determination.

Cold flow rate (CF): The obtained polybutadiene was kept at 50 ° C, and a glass tube having an inner diameter of 6.0 mm was suctioned at a differential pressure of 325 mmHg for 10 minutes, and the weight of the inhaled polymer was measured to determine every 1 minute. The amount of polymer that was extracted (mg/min).

Determination of the number of long-chain branching points of polybutadiene: 1 g of the obtained polybutadiene and 2.5 mol equivalent of p-toluenesulfonyl hydrazine (p-TSH: hydrogen generator) were added to 100 mL of p-xylene. The reaction was carried out at 150 ° C for 5 hours. Thereafter, the hydrogenated polybutadiene was obtained by a step of hot filtration, reprecipitation (poor solvent: methanol), and washing (washing medium: ethanol). The confirmation of the hydrogenation reaction was carried out using FT-IR and ¹ H-NMR, and the reaction was confirmed to proceed.

The polybutadiene maintains its branched structure by hydrogenation, and is converted into a polyethylene having a long-chain branch (branched chain having 6 or more carbon atoms) and a short-chain branch (ethyl) derived from a vinyl-1,2 structure. Here, the polybutadiene contains a structure of cis-1,4, trans-1,4, a vinyl-1,2, and a hydrogenated structure.

[Chemical 2] 70 mg of the obtained hydrogenated polybutadiene was sampled into an NMR measuring tube, and 0.7 mL of ODCB (o-dichlorobenzene) / C ₆ D ₆ (4/1 (volume ratio)) was added, and the tube was sealed. The sample was then heated and dissolved using a heating bath and a heat gun to homogenize for ¹³ C-NMR measurement.

¹³ C-NMR measurement was carried out using EX-400 manufactured by JEOL Ltd.

First, in order to quantify the short-chain branching point (vinyl content), ¹³ C-NMR (normal single pulse measurement) was carried out at a measurement temperature of 130 ° C and a cumulative number of times of 54,000 times.

In the usual ¹³ C-NMR measurement, the long-chain branching point present in the polymer is not quantifiable due to the dynamic range caused by the main chain methylene peak, but the short chain based on the vinyl-1,2 structure. The branch points can be fully quantified. That is, the ratio of the methylene carbon number to the methine carbon number is obtained from the ratio of the peak area of the peak portion of the short-chain branch point methyl carbon to the peak area of the peak portion of the main chain methylene carbon. The relationship between the short chain branch points per short monomer unit (short chain branch points / 10,000 monomer units) can be determined.

The main peak of the ¹³ C-NMR (single pulse) spectrum of the hydrogenated polybutadiene and its chemical shift are shown in the following table. The chemical shift is based on TMS (tetramethyl decane).

[Table S1] The peak area of the main chain methylene group S _M = the sum of the peak areas of the peak group [M1, M2, M3], and the peak area of the short chain branch point methyl group S _B = the peak part [B1] In the peak area, the methylene carbon number based on the cis-1,4 structure and the trans-1,4 structure becomes S _M -S _B (proportional number), cis-1,4 structure and trans The number of monomer units of the -1,4 structure is (S _M -S _B )/4 (proportional number). The number of monomer units of the vinyl-1,2 structure, that is, the number of short chain branch points becomes S _B (proportional number).

Therefore, the number of short-chain branch points per unit of butadiene monomer (short-chain branch points/1 monomer unit) can be calculated as follows: S _B /[(S _M -S _B )/4+S _B ]×100 (mol%) (1).

Next, in order to quantify the ratio of the long-chain branch point to the short-chain branch point and the long-chain branch point, ¹³ C-NMR DEPT 90° measurement was performed at a measurement temperature of 130 ° C, an observation range of 10 to 42 ppm, and a cumulative number of times of 64,000 times.

The DEPT (Distorsion Less Enhancement by Polarization Transfer) method uses a method in which the ¹³ C-NMR spectrum is distinguished from the intensity of the pulse angle (θ) of the irradiation to distinguish the carbon number. In the DEPT 90° measurement (pulse given θ=90°), the peaks of the methyl group and the methylene carbon disappeared or largely attenuated and the peak of the methine carbon was observed. That is, the peak of the methylene carbon based on the main chain of the hydrogenated polymer disappears or is greatly attenuated by the DEPT90° measurement, and the main chain methylene peak which is usually high in the peak of the NMR measurement is caused. The problem of the dynamic range. As a result, the long-chain branching point which is present in a trace amount in the polymer can be sensed with high sensitivity.

As a result of the DEPT90° measurement, the hypomethyl carbon of the short-chain branch point and the methine carbon of the long-chain branch point can be observed with different sensitivity (intensity, S/N ratio) for different peaks. In other words, the ratio of the peak area of the peak portion of the short-chain branch point methyl carbon to the peak area of the peak portion of the methine carbon of the long-chain branch point can be obtained from the ratio of the long-chain branch point to the short The ratio of chain branch points (long chain branch points / short chain branch points).

The main peak of the ¹³ C-NMR (DEPT 90°) spectrum of the hydrogenated polybutadiene and its chemical shift are shown in the following table. The chemical shift is obtained by using TMS (tetramethyl decane) as a reference.

[Table S2] The peak area of the short-chain branching point methyl group (S _B ^* ) = the peak area of the peak portion [B1 ^* ], and the peak area of the long-chain branch point methyl group (S _L ) = peak portion [L] In the peak area, the ratio of the number of long-chain branch points to the number of short-chain branch points (long-chain branch points/short-chain branch points) can be calculated as follows: S _L /S _B ^* (2).

Further, the number of short-chain branch points per unit of the butadiene monomer (the number of short-chain branch points/1 monomer unit) and the long-chain branch point calculated from the above formula (2) can be calculated from the above formula (1). The number of long chain branch points per 10,000 butadiene monomer units was calculated as the ratio of the number of short chain branch points (long chain branch points/short chain branch points). That is, the number of long chain branch points per 10,000 butadiene monomer units can be calculated by the following formula: (long chain branch points / short chain branch points) × (short chain branch points / 1 monomer Unit) × 10,000.

Viscoelasticity measurement (measurement of Y _(50%) / Y _(10%) ): 7.5 g of polybutadiene was dissolved in 200 ml of toluene. Then, 7.5 g of mobile paraffin was added to the solution, and the mixture was stirred until homogeneous. The obtained solution was poured into a stainless steel tray equipped with a PET film, and vacuum-dried at 60 ° C for 8 hours using a vacuum dryer. The 50% by mass solution of the flowing paraffin of the obtained polybutadiene was 15 g.

1.5 g of polybutadiene was dissolved in 200 ml of toluene. Then, 13.5 g of flowing paraffin was added to the solution, and the mixture was stirred until homogeneous. The obtained solution was poured onto a stainless steel shallow pan provided with a PET film, and vacuum-dried at 60 ° C for 8 hours using a vacuum dryer. The 10% by mass solution of the flowing paraffin of the obtained polybutadiene was 15 g.

The angular frequency dependence of the storage elastic modulus G' and the loss elastic modulus G'' of the liquid paraffin 50% by mass solution of the obtained polybutadiene and the 10% by mass solution were measured, respectively. The measurement was carried out in a nitrogen stream using a ARES manufactured by TA Instruments, which was mounted with a parallel plate having a diameter of 25 mm or 7.9 mm. The measurement frequency range is 100 to 0.01 rad/s, and the measurement temperatures are 0 ° C, 20 ° C, 40 ° C, 60 ° C, 80 ° C, and 100 ° C. Using JDFerry's "Viscoelastic Properties of Polymers, 3rd ed." (John Wiley & Sons, 1990), the overlap of temperature and time gives the frequency dependence of G' and G'' over a wide frequency range. curve.

Using the obtained main curve of the frequency dependence of G' and G'', the concentration of the liquid paraffin solution C of the polybutadiene when X = G'' / C ² = 20,000 Pa (concentration conversion G'') is obtained. And find Y=G'/C ² (concentration conversion G'). Then, the ratio of Y (Y _(50%) ) determined from the measurement of the _{50% by} mass solution of the flowing paraffin to the Y (Y _(10%) ) determined from the measurement of the 10% by mass of the flowing paraffin solution (Y _{) was} calculated. _(50%) /Y _(10%) ).

(Evaluation of composition) Tensile stress: 100% and 300% tensile stress were measured in accordance with JIS-K6251, and the comparative example R1 shown in Table 3 was set to 100, and the index was expressed (the larger the index, the better).

Wear resistance (Lamborn abrasion resistance): The Lamborn abrasion resistance is measured by a slip ratio of 40% in accordance with the measurement method specified in JIS-K6264, and the comparative example R1 shown in Table 3 is taken as 100, and is expressed by an index ( The bigger the index, the better.)

Backlash elasticity: According to JIS-K6255, the backlash elasticity was measured at room temperature using a Dunlop Tripsometer, and the comparative example R1 shown in Table 3 was set to 100, and the index was expressed (the larger the index, the better).

Low heat build-up ‧ permanent deformation: Measured according to the measurement method specified in JIS-K6265, and the comparative example R1 described in Table 3 was set to 100, and the index was expressed (the larger the index, the better).

Low fuel cost (tan δ (60 ° C)): measured using a viscoelasticity measuring device (EPLEXOR 100N manufactured by GABO Co., Ltd.) at a temperature range of -120 ° C to 100 ° C, a frequency of 16 Hz, a dynamic deformation of 0.3%, and a tan δ of 60 ° C. As an indicator of low fuel cost. The comparative example R1 described in Table 3 was set to 100 and indexed. The lower the cost of fuel (tan δ), the better. Moreover, the index in Table 3 is written as follows: the lower the cost of fuel, the better.

Storage elastic modulus (E') at -30 °C: measured using a viscoelasticity measuring device (EPLEXOR 100N manufactured by GABO Co., Ltd.) at a temperature range of -120 ° C to 100 ° C, a frequency of 16 Hz, and a dynamic deformation of 0.3%, using a storage of -30 ° C. Elastic coefficient (E'). The comparative example R1 shown in Table 3 was set to 100, and the index was expressed (the larger the index, the lower the elastic modulus at -30 ° C, which is good).

(Example 1) The inside of the autoclave having a content of 1.5 L was substituted with nitrogen, and a solution of 545 ml of a cyclohexane solvent and 550 ml of butadiene was charged. Next, 3.4 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.88 ml of a cyclohexane solution (0.005 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Gd(dpm) ₃ ), 肆 was added. A toluene solution (0.004 mol/L) of 2.2 ml of triphenyl carbenium tetrakis (pentafluorophenyl) boronate. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added to terminate the polymerization. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. Then, the recovered polybutadiene was vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1 and Table 1-2.

(Example 2) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 500 ml of a cyclohexane solvent and 500 ml of butadiene was charged. Then, 1.5 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.80 ml of a cyclohexane solution (0.005 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Gd(dpm) ₃ ), hydrogenation was added. A solution of 0.4 ml of a diisobutylaluminum cyclohexane solution (1 mol/L) and a toluene solution (0.004 mol/L) of ruthenium (pentafluorophenyl)borate triphenylcarbenium salt (2.04 mol/L). After polymerization at 50 ° C for 25 minutes, 6 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 3) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 545 ml of a cyclohexane solvent and 550 ml of butadiene was charged. Next, 3.4 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.88 ml of a cyclohexane solution (0.005 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Gd(dpm) ₃ ), 肆 was added. A toluene solution (0.004 mol/L) of (pentafluorophenyl)borate triphenylcarbenium salt (2.2 ml). After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 4) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and 495 ml of a cyclohexane solvent and 500 ml of butadiene were added. Next, 3.2 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 0.8 ml of a cyclohexane solution (0.005 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Gd(dpm) ₃ ) was added, and then ruthenium was added. Toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt 2.0 ml. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 5) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 545 ml of a cyclohexane solvent and 550 ml of butadiene was charged. Then, 2.85 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.88 ml of a cyclohexane solution (0.005 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Gd(dpm) ₃ ), 肆 was added. A toluene solution (0.004 mol/L) of (pentafluorophenyl)borate triphenylcarbenium salt (2.2 ml). After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 6) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 500 ml of a cyclohexane solvent and 500 ml of butadiene was charged. Then, 3.4 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 0.4 ml of a cyclohexane solution (0.01 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Tb(dpm) ₃ ) was added, and then ruthenium was added. Toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt 2.0 ml. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1 and Table 1-2.

(Example 7) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution comprising 400 ml of a cyclohexane solvent and 400 ml of butadiene was added thereto. Then, 4.0 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 0.4 ml of a cyclohexane solution (0.01 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Tb(dpm) ₃ ) was added, and then ruthenium was added. Toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt 2.0 ml. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 8) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 295 ml of a cyclohexane solvent and 300 ml of butadiene was charged. Then, 1.8 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.24 ml of a cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Tb(dpm) ₃ ), ruthenium was added. A toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt (1.2 ml). After polymerization at 50 ° C for 20 minutes, 4 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 9) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 295 ml of a cyclohexane solvent and 300 ml of butadiene was charged. Then, 1.95 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then add 0.24 ml of a cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) (Tb(dpm) ₃ ) and add hydrazine ( Toluene solution of pentafluorophenyl)boronic acid triphenylcarbenium salt (0.004 mol/L) 1.2 ml. After polymerization at 50 ° C for 25 minutes, 4 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 10) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 545 ml of a cyclohexane solvent and 550 ml of butadiene was charged. Then, 3.4 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, after adding 0.88 ml of a cyclohexane solution (0.005 mol/L) of bis(2,2,6,6-tetramethyl-3,5-heptanedionate) hydrazine (Dy(dpm) ₃ ), hydrazine was added. A toluene solution (0.004 mol/L) of (pentafluorophenyl)borate triphenylcarbenium salt (2.2 ml). After polymerization at 50 ° C for 20 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 11) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 295 ml of a cyclohexane solvent and 300 ml of butadiene was charged. Then, 1.95 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, a solution of bis(2,2,6,6-tetramethyl-3,5-heptanedionate) hydrazine (Dy(dpm) ₃ ) in cyclohexane (0.005 mol/L) 0.48 ml was added and then hydrazine was added ( Toluene solution of pentafluorophenyl)boronic acid triphenylcarbenium salt (0.004 mol/L) 1.2 ml. After polymerization at 50 ° C for 25 minutes, 4 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 12) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 245 ml of a cyclohexane solvent and 250 ml of butadiene was charged. Then 1.5 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then add 0.4 ml of cyclohexane solution (0.005 mol/L) of gin (2,2,6,6-tetramethyl-3,5-heptanedionate) hydrazine (Dy(dpm) ₃ ) and add hydrazine ( Toluene solution of pentafluorophenyl)boronic acid triphenylcarbenium salt (0.004 mol/L) 1.0 ml. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 13) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 495 ml of a cyclohexane solvent and 500 ml of butadiene was charged. Then, 2.7 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then add 1.0 ml of cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Ho(dpm) ₃ ) and add hydrazine ( Toluene solution of pentafluorophenyl)boronic acid triphenylcarbenium salt (0.004 mol/L) 5.0 ml. After polymerization at 50 ° C for 25 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 14) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 395 ml of a cyclohexane solvent and 400 ml of butadiene was charged. Then 2.5 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 1.6 ml of a cyclohexane solution (0.01 mol/L) of ginseng (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Tm(dpm) ₃ ) was added, and then hydrazine was added ( Toluene solution of pentafluorophenyl)boronic acid triphenylcarbenium salt (0.004 mol/L) 8.0 ml. After polymerization at 50 ° C for 20 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 15) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 245 ml of a cyclohexane solvent and 250 ml of butadiene was charged. Then 1.5 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 0.5 ml of a cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Er(dpm) ₃ ) was added, and then ruthenium was added. Toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt 2.5 ml. After polymerization at 50 ° C for 20 minutes, 3 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 16) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 495 ml of a cyclohexane solvent and 500 ml of butadiene was charged. Then, 3.1 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 1.0 ml of a cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Er(dpm) ₃ ) was added, and then ruthenium was added. A solution of toluene (pentafluorophenyl)borate triphenylcarbenium salt (0.004 mol/L) 5.0 ml. After polymerization at 50 ° C for 20 minutes, 5 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Example 17) The inside of the autoclave having a content of 1.5 L was replaced with nitrogen, and a solution of 245 ml of a cyclohexane solvent and 250 ml of butadiene was charged. Then 1.5 ml of a solution of triethylaluminum (TEAL) in cyclohexane (2 mol/L) was added. Then, 0.5 ml of a cyclohexane solution (0.01 mol/L) of ruthenium (2,2,6,6-tetramethyl-3,5-heptanedionate) ruthenium (Er(dpm) ₃ ) was added, and then ruthenium was added. Toluene solution (0.004 mol/L) of (pentafluorophenyl)boronic acid triphenylcarbenium salt 2.5 ml. After polymerization at 50 ° C for 25 minutes, 3 ml of an ethanol solution containing an anti-aging agent was added and the polymerization was stopped. After the inside of the autoclave was released, the polymerization liquid was poured into ethanol and polybutadiene was recovered. The recovered polybutadiene was then vacuum dried at 80 ° C for 3 hours. The physical properties of the synthesized polybutadiene were then determined. The measurement results of the polymerization conditions, the polymerization results, and the physical properties of the synthesized polybutadiene are shown in Table 1-1.

(Comparative Example 1) The measurement results of the physical properties of JSR BR01 (polybutadiene obtained by polymerization using a Ni-based catalyst) manufactured by JSR Co., Ltd. are shown in Table 1-1 and Table 1-2.

【Table 1-1】

As shown in Table 1-1, the polybutadiene obtained in Examples 1 to 17, the molecular linearity index Tcp/ML _{1 + 4} is a large value of 1.3 or more and 5.0, and the cold flow velocity (CF) is Below 5.5 mg/min, the cold flow characteristics are also excellent.

[Table 1-2]

(Example R1) Using the polybutadiene synthesized by Gd(dpm) ₃ in Example 1, according to the blending formula shown in Table 2, natural rubber, carbon black, zinc oxide, stearic acid, and the like were added in a Plastomill. The anti-aging agent, the oil and the kneading are mixed once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

(Example R2) Using the polybutadiene synthesized in Tb(dpm) ₃ in Example 6, according to the blending formula shown in Table 2, natural rubber, carbon black, zinc oxide, stearic acid, and the like were added in a Plastomill. The anti-aging agent, the oil and the kneading are mixed once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

(Example R3) Using the polybutadiene synthesized in Dy(dpm) ₃ in Example 10, according to the blending formula shown in Table 2, natural rubber, carbon black, zinc oxide, stearic acid, and the like were added in a Plastomill. The anti-aging agent, the oil and the kneading are mixed once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

(Example R4) The polybutadiene synthesized in Ho (dpm) _{3 was} used in Example 13 and the natural rubber, carbon black, zinc oxide, stearic acid, and the like were added in a Plastomill according to the blending formula shown in Table 2. The anti-aging agent, the oil and the kneading are mixed once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

(Example R5) The polybutadiene synthesized in Er (dpm) _{3 was} used in Example 16 and the natural rubber, carbon black, zinc oxide, stearic acid, and the like were added in a Plastomill according to the blending formula shown in Table 2. The anti-aging agent, the oil and the kneading are mixed once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

(Comparative Example R1) JSR BR01 manufactured by JSR Co., Ltd. of Comparative Example 1 was used as a polybutadiene, and a blending formula shown in Table 2 was used, and natural rubber, carbon black, zinc oxide, and stearic acid were added in a Plastomill. The blending of the anti-aging agent, the oil and the kneading is carried out once, and then the addition of the vulcanization accelerator and the secondary addition of sulfur are carried out by means of a roll to obtain a blended rubber. Further, the blended rubber was molded in accordance with the desired physical properties, and subjected to compression and sulfurization at 150 ° C to obtain a sulfur-added product and carry out physical property measurement. The physical property measurement results of the various blends are shown in Table 3.

【Table 2】 BR01: JSR (share) JSR BR01 Natural rubber: RSS#3 Carbon black: ISAF Zinc oxide: Sakai Chemical Industry Sazex No. 1 stearic acid: Kao stearic acid Anti-aging agent: Sumitomo Chemical antigen6C Oil: Japan Energy Naphthenic oil vulcanization accelerator: Da Ning Xinxing Chemical Industry Co., Ltd. Nocceler NS Sulfur: Fine Well Chemical Industry Co., Ltd. The number of bismuth in Sulphur Table 2 is part by mass.

【table 3】

The number in Table 3 is based on the fact that each characteristic of the comparative example R1 of JSR BR01 manufactured by JSR Co., Ltd. is used as the reference (100), and the index of each item is expressed as 値. The higher the number, the better the characteristics.

As shown in Table 3, the compositions of Examples R1 to R5 of the polybutadiene obtained in Examples 1, 6, 10, 13, and 16 were compared with Comparative Example R1 using JSR BR01 manufactured by JSR Co., Ltd. The composition has excellent rebound elasticity, low temperature storage elastic modulus at -30 ° C, low fuel cost (tan δ (60 ° C)), and abrasion resistance, low heat build-up, and permanent deformation are equivalent or more. [Industry Utilization]

According to the present invention, it is possible to provide a polybutadiene having a relatively large Tcp/ML _{1 + 4 which} is an index of molecular linearity and excellent in cold flow characteristics. Further, according to the present invention, there is also provided a polybutadiene having excellent characteristics possessed by polybutadiene having a small degree of branching, for example, excellent wear resistance, low heat build-up, rebound elasticity, and excellent cold flow characteristics. . The polybutadiene of the present invention is excellent in abrasion resistance, low heat build-up property, rebound elasticity, and the like, and is suitably used for a rubber composition, particularly a rubber composition for a tire.

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Claims (12)

A polybutadiene having a ratio of a 5% toluene solution viscosity (Tcp) measured at 25 ° C to a Mohs viscosity (ML _{1 + 4} ) at 100 ° C (Tcp/ML _{1 + 4} ) of 1.3 or more and 5.0 or less. The molecular weight distribution (Mw/Mn) is 2.0 or more and less than 4, and the cold flow rate (CF) is 5.5 mg/min or less. The polybutadiene according to claim 1, wherein the Mohs viscosity (ML _{1 + 4} ) at 100 ° C is 25 or more and 60 or less. A polybutadiene having a number of long chain branching points per 10,000 butadiene monomer units determined by ¹³ C-NMR measurement of hydrogenated polybutadiene (only long chain branch points are referred to as two or more The branching chain of the carbon number 6 or more formed by the butadiene unit is bonded to the branch point of the main chain), and the storage elastic modulus G of the 50% by mass solution of the flowable paraffin of the polybutadiene and the 10 mass% solution 'and the loss of the elastic coefficient G'', the frequency dependence is determined by the concentration conversion G'', and the concentration conversion G' is X=G''/C ² = 20,000Pa, Y=G'/C ² (only C is the concentration of the solution). The ratio of Y is defined as [Y _(50%) / Y _(10%) (but Y _(50%) is determined from the measurement of a 50% by mass solution of flowing paraffin, Y _{( 10%)} is determined from the measurement of a liquid paraffin 10% by mass solution.)] is greater than 2. A polybutadiene having a number of long chain branch points per 10,000 butadiene monomer units determined by ¹³ C-NMR measurement of hydrogenated polybutadiene (only long chain branch points are referred to as two or more) The number of branched chains in which the number of carbon atoms of 6 or more formed by the butadiene unit is bonded to the main chain is 9 or less, and the cold flow rate (CF) is 5.5 mg/min or less. A polybutadiene having a ratio of a 5% toluene solution viscosity (Tcp) measured at 25 ° C to a Mohs viscosity (ML _{1 + 4} ) at 100 ° C (Tcp/ML _{1 + 4} ) of 1.3 or more, Determination of the angular dependence of the density dependence of the storage coefficient of elasticity of the 50% by mass solution of polybutadiene and the storage elastic modulus G' of the 10% by mass solution and the loss elastic coefficient G'', and the concentration conversion G' The ratio of Y defined by Y=G'/C ² (where C is the solution concentration) at X=G''/C ² = 20,000 Pa [Y _(50%) / Y _(10%) (only Y _{( 50%)} is determined from the measurement of a 50% by mass solution of a flowing paraffin, and Y _(10%) is obtained by measuring 値 from a liquid paraffin 10% by mass solution.)] is more than 2. The polybutadiene according to any one of claims 1 to 5, wherein the cis-1,4-structure content is 90% or more. A rubber composition comprising the polybutadiene according to any one of claims 1 to 6. A rubber composition for a tire, which comprises the polybutadiene according to any one of claims 1 to 6. A rubber composition for a tire according to claim 8 which contains a diene polymer other than polybutadiene and a rubber reinforcing agent. The rubber composition for a tire according to the ninth aspect of the invention, wherein the diene polymer is at least one of natural rubber, styrene-butadiene rubber, and polyisoprene. The rubber composition for a tire according to claim 9 or 10, wherein the rubber reinforcing agent is carbon black and/or cerium oxide. A tire composition for use in a rubber composition for a tire according to any one of claims 8 to 11 as a rubber substrate.