JP2010270313A - Rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition capable of improving the grip performance, low temperature characteristics and destruction resistant property of a tire. <P>SOLUTION: The rubber composition includes a rubber component including (A) a high molecular weight polymer having a 2.0×10<SP>5</SP>to 3.0×10<SP>6</SP>polystyrene equivalent weight-average molecular weight, and (B) a low molecular weight polymer having a 2.0×10<SP>3</SP>to 1.0×10<SP>5</SP>polystyrene equivalent weight-average molecular weight including (B-1) a block component of an aromatic vinyl compound, (B-2) a block component of a conjugated diene compound, and (B-3) a block component of an aromatic vinyl compound and a conjugated diene compound as an aromatic vinyl compound-conjugated diene compound copolymer or a conjugated diene compound polymer. (B) The low molecular weight polymer has (B-3) the block component at least at one terminal, and its polystyrene-equivalent peak molecular weight in the aromatic vinyl compound block is 1,000 or higher. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the rubber composition, and more particularly to a rubber composition capable of improving the low temperature characteristics, grip performance and fracture resistance of the tire.

  In response to the evolution of advanced power performance of automobiles in recent years, more excellent handling stability, particularly high grip performance on dry road surfaces, has been demanded as tire characteristics. In order to ensure the grip performance on the dry road surface, it is necessary to improve the hysteresis loss of the rubber composition used for the tread. On the other hand, from the viewpoint of economy and safety, it is also an important issue to sufficiently secure the fracture resistance of the tire. And in order to improve the hysteresis loss of a rubber composition, the method of blending a low molecular weight polymer is known (for example, refer Unexamined-Japanese-Patent No. 63-101440 (patent document 1)). Furthermore, in order to improve both hysteresis loss and wear resistance, a method of introducing a block of an aromatic vinyl compound into a low molecular weight polymer has been reported (for example, JP-A-4-45137 (Patent Document 2)). JP-A-6-80824 (Patent Document 3), JP-A-7-157597 (Patent Document 4) and JP-A-9-278844 (Patent Document 5)).

JP 63-101440 A JP-A-4-45137 Japanese Patent Laid-Open No. 6-80824 JP-A-7-157597 Japanese Patent Laid-Open No. 9-278844

  However, as a result of investigation by the present inventors, in the conventional method using various low molecular weight polymers, microphase separation is formed between the aromatic vinyl compound portion and the conjugated diene compound portion forming the low molecular weight polymer. The compatibility between the low molecular weight polymer and the matrix component composed of the high molecular weight polymer cannot be sufficiently obtained, or the degree of polymerization of the aromatic vinyl compound block is insufficient. Regarding the effect, it was found that there is still room for improvement. Further, when the vinyl bond amount in the conjugated diene compound portion of the low molecular weight polymer is too high, there is a problem that low temperature characteristics such as braking performance at low temperature and low temperature operability are deteriorated.

  Accordingly, an object of the present invention is to provide a rubber composition capable of solving the above-described problems of the prior art and improving the grip performance, low temperature characteristics and fracture resistance of a tire. Another object of the present invention is to provide a tire using such a rubber composition and having excellent grip performance, low-temperature characteristics and fracture resistance.

  As a result of intensive studies to achieve the above object, the present inventors have determined that a rubber component containing a high molecular weight polymer having a specific molecular weight has a specific molecular weight and structure, and further an aromatic vinyl compound block is specified. It has been found that the grip performance, low temperature characteristics and fracture resistance can be improved by using a rubber composition containing a low molecular weight polymer having a peak molecular weight of, for a tire, and the present invention has been completed.

That is, the rubber composition of the present invention is an aromatic vinyl compound-conjugated diene compound copolymer or a conjugated diene compound polymer, and the polystyrene equivalent weight average molecular weight is 2.0 × 10 ^{5 to} 3.0 × 10 ^6. An aromatic vinyl compound-conjugated diene compound copolymer having a polystyrene-reduced weight average molecular weight of 2.0 × 10 ^{3 to} 1.0 × 10 ⁵ with respect to the rubber component containing the polymer (A), the block of the aromatic vinyl compound A low molecular weight polymer (B) comprising a component (B-1), a block component (B-2) of a conjugated diene compound, and a block component (B-3) of an aromatic vinyl compound and a conjugated diene compound is blended. The low molecular weight polymer (B) has the block component (B-3) at least at one end of the low molecular weight polymer (B), and the aromatic vinyl compound of the low molecular weight polymer (B). Po in the block Peak molecular weight of the styrene conversion is equal to or 1,000 or more.

  “Polystyrene equivalent weight average molecular weight” and “polystyrene equivalent peak molecular weight” are values measured by gel permeation chromatography (GPC). “Aromatic vinyl compound block component (B-1)” refers to an aromatic vinyl compound block in which structural units derived from an aromatic vinyl compound are linked, and “block component of conjugated diene compound (B-2)”. "Refers to a conjugated diene compound block in which structural units derived from a conjugated diene compound are linked, and" block component (B-3) of an aromatic vinyl compound and a conjugated diene compound "refers to an aromatic vinyl compound and a conjugated diene compound. This refers to a portion in which structural units derived from and are linked at random.

  In a preferred example of the rubber composition of the present invention, the low molecular weight polymer (B) forms a (B-1)-(B-2)-(B-3) type structure. The notation of (B-1)-(B-2)-(B-3) is the block component (B-1), block component (B-2) and block in the structure of the low molecular weight polymer (B). The arrangement | sequence of a component (B-3) is shown.

  In the rubber composition of the present invention, the aromatic vinyl compound block preferably has a polystyrene-equivalent weight average molecular weight of 800 to 40,000.

  In the rubber composition of the present invention, the block component (B-3) preferably has an aromatic vinyl compound bond amount of 5 to 90% by mass.

  In the rubber composition of the present invention, the low molecular weight polymer (B) preferably has a vinyl bond content in the conjugated diene compound portion of less than 30% by mass.

  In the rubber composition of the present invention, examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6. -Trimethylstyrene, p-tert-butyl-α-methylstyrene and p-tert-butylstyrene are preferred, and among these, styrene is particularly preferred.

  In the rubber composition of the present invention, the conjugated diene compound is preferably 1,3-butadiene, isoprene and cyclopentadiene.

  In another preferred embodiment of the rubber composition of the present invention, the low molecular weight polymer (B) is obtained by sequentially polymerizing each block component according to its sequence while controlling the composition ratio of monomers to be polymerized. .

  In the rubber composition of the present invention, the low molecular weight polymer (B) has a mass ratio (X / Y) of the bond amount (X) of the aromatic vinyl compound and the bond amount (Y) of the conjugated diene compound is 5 / 95 to 95/5 is preferable.

  In the rubber composition of this invention, it is preferable that the compounding quantity of the said low molecular weight polymer (B) is 2-100 mass parts with respect to 100 mass parts of said rubber components.

  In another preferable example of the rubber composition of the present invention, the filler is further contained in an amount of 10 to 200 parts by mass with respect to 100 parts by mass of the rubber component. Here, as the filler, carbon black is preferable.

  The tire of the present invention is characterized by using the above rubber composition for any of the tire members.

  According to the present invention, a rubber component containing a high molecular weight polymer having a specific molecular weight is blended with a low molecular weight polymer having a specific molecular weight and structure and an aromatic vinyl compound block having a specific peak molecular weight. Thus, it is possible to provide a rubber composition capable of improving the grip performance, low temperature characteristics and fracture resistance of a tire. Moreover, the tire excellent in grip performance, low-temperature characteristics, and fracture resistance using such a rubber composition can be provided.

The present invention is described in detail below. The rubber composition of the present invention is an aromatic vinyl compound-conjugated diene compound copolymer or a conjugated diene compound polymer, and has a polystyrene equivalent weight average molecular weight of 2.0 × 10 ^{5 to} 3.0 × 10 ^6. An aromatic vinyl compound-conjugated diene compound copolymer having a polystyrene-reduced weight average molecular weight of 2.0 × 10 ^{3 to} 1.0 × 10 ⁵ with respect to the rubber component containing (A), the block component of the aromatic vinyl compound ( B-1), a block component (B-2) of a conjugated diene compound, and a low molecular weight polymer (B) comprising a block component (B-3) of an aromatic vinyl compound and a conjugated diene compound, The low molecular weight polymer (B) has the block component (B-3) at least at one end of the low molecular weight polymer (B), and the low molecular weight polymer (B) has an aromatic vinyl compound block. Police Peak molecular weight of down conversion is equal to or 1,000 or more.

The rubber composition of the present invention has a polystyrene equivalent weight average molecular weight of 2.0 × 10 ^{3 to} 1.0 in a rubber component containing a high molecular weight polymer (A) having a polystyrene equivalent weight average molecular weight of 2.0 × 10 ^{5 to} 3.0 × 10 ^6. A low molecular weight polymer (B) of × 10 ⁵ is blended, and hysteresis loss can be improved. The low molecular weight polymer (B) has a block component (B-3) of an aromatic vinyl compound and a conjugated diene compound introduced into at least one of its ends, whereby the low molecular weight polymer (B) Suppresses the formation of microphase separation in the resin, and is sufficient for either aromatic vinyl compound-conjugated diene compound copolymer or conjugated diene compound polymer (ie, for high molecular weight polymer (A)) It is possible to ensure compatibility. And the formation of microphase separation of the low molecular weight polymer (B) is suppressed, and the fracture strength of the rubber composition is ensured by ensuring the compatibility between the low molecular weight polymer (B) and the high molecular weight polymer (A). In addition, hysteresis loss can be improved. Moreover, by eliminating the above-described problem of the formation of microphase separation and compatibility, the storage elastic modulus (G ′) at low temperature is lowered, and the low temperature characteristics such as brake performance and low temperature operability can be improved. .

The high molecular weight polymer (A) of the rubber composition of the present invention is an aromatic vinyl compound-conjugated diene compound copolymer or conjugated diene compound polymer having a polystyrene-equivalent weight average molecular weight of 2.0 × 10 ^{5 to} 3.0 × 10 ^6. It is necessary to be. When the weight average molecular weight in terms of polystyrene of the high molecular weight polymer (A) is less than 2.0 × 10 ⁵ , the fracture characteristics of the rubber composition may be deteriorated. On the other hand, when it exceeds 3.0 × 10 ⁶ , the viscosity of the polymerization solution is high. It becomes too low and productivity becomes low. In addition, the polystyrene conversion weight average molecular weight of the high molecular weight polymer (A) is preferably 2.0 × 10 ^{5 to} 2.5 × 10 ⁶ , and more preferably 2.0 × 10 ^{5 to} 2.0 × 10 ⁶ . Moreover, as said high molecular weight polymer (A), any of a linear polymer and a branched polymer may be used, and it can also modify | denature using a modifier etc. Specific examples of the high molecular weight polymer (A) include natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), and isobutylene isoprene rubber. Synthetic rubbers such as (IIR), halogenated butyl rubber, styrene-isoprene copolymer rubber (SIR), chloroprene rubber (CR) and the like, and these high molecular weight polymers (A) may be used alone. Two or more kinds may be blended and used.

  The high molecular weight polymer (A) is produced by copolymerizing an aromatic vinyl compound and a conjugated diene compound or polymerizing a conjugated diene compound. Moreover, it does not restrict | limit especially as a manufacturing method of the said high molecular weight polymer (A), For example, the method similar to the low molecular weight polymer (B) mentioned later etc. are mentioned. Here, examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, p- Examples thereof include tert-butyl-α-methylstyrene and p-tert-butylstyrene. These aromatic vinyl compounds may be used alone or in combination of two or more. On the other hand, examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and cyclopentadiene. These conjugated diene compounds may be used alone or in combination of two or more. Among the aromatic vinyl compounds, styrene is particularly preferable, and among the conjugated diene compounds, 1,3-butadiene, isoprene and cyclopentadiene are particularly preferable.

  The rubber component of the rubber composition of the present invention is required to contain the high molecular weight polymer (A). Here, when a rubber component other than the high molecular weight polymer (A) is contained, a general rubber component used in the rubber industry can be blended. Specific examples of rubber components other than the high molecular weight polymer (A) include natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), and isobutylene isoprene. Rubber (IIR), styrene-isoprene copolymer rubber (SIR), butadiene-isoprene copolymer rubber (BIR), nitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), etc. Is mentioned. In addition, rubber components other than these high molecular weight polymers (A) may be used individually by 1 type, and may be used by blending 2 or more types.

The low molecular weight polymer (B) of the rubber composition of the present invention is required to be an aromatic vinyl compound-conjugated diene compound copolymer having a polystyrene-equivalent weight average molecular weight of 2.0 × 10 ^{3 to} 1.0 × 10 ⁵ . If the polystyrene-reduced weight average molecular weight of the low molecular weight polymer (B) is less than 2.0 × 10 ³ , the fracture characteristics of the rubber composition may be reduced, whereas if it exceeds 1.0 × 10 ⁵ , the workability of the rubber composition may be reduced. Decreases. In addition, the polystyrene conversion weight average molecular weight of the low molecular weight polymer (B) is preferably 2.0 × 10 ^{3 to} 8.0 × 10 ⁴ , and more preferably 5.0 × 10 ^{3 to} 8.0 × 10 ⁴ .

The low molecular weight polymer (B) includes an aromatic vinyl compound block component (B-1), a conjugated diene compound block component (B-2), and an aromatic vinyl compound and conjugated diene compound block component (B- 3), and the block component (B-3) is introduced into at least one of the terminals of the low molecular weight polymer (B). A low molecular weight polymer (B) having a block component (B-1) of an aromatic vinyl compound and a block component (B-2) of a conjugated diene compound has at least one terminal and constitutes each block component. If the block component (B-3) composed of a monomer unit is not introduced, microphase separation is formed. Therefore, as the structure of the low molecular weight polymer (B), for example, [(B-1)-(B-2)] _n- (B-3) type, [(B-2)-(B-1) ] _n- (B-3) type, (B-3)-[(B-1)-(B-2)] _n- (B-3) type, (B-2)-[(B-1) -(B-2)] _n- (B-3) type, (B-1)-[(B-2)-(B-1)] _n- (B-3) type, etc. , N is an integer from 1 to 10). Among these, in order to form a more effective phase separation structure, the (B-1)-(B-2)-(B-3) type and ( The B-3)-(B-2)-(B-1) type is particularly preferred. In addition, the boundary between each block component does not need to be clearly distinguished, for example, between an aromatic vinyl compound and a conjugated diene compound between a block component (B-1) and a block component (B-2). You may form the part consisting of a mixture, what is called a taper structure. Thus, if a taper structure is formed in the boundary of the connected block component, compatibility with a high molecular weight polymer (A) will improve further. Moreover, the said low molecular weight polymer (B) is good also as a branched polymer synthesize | combined in this arrangement | sequence using the coupling agent, and can also modify | denaturate using a modifier etc. Further, when a plurality of the same block components are present in the low molecular weight polymer (B), it is not necessary to prepare the types and compositions of the monomers constituting the block components. In addition, the structure of a low molecular weight polymer (B) may be used individually by 1 type, and may be used by blending 2 or more types.

  The block component (B-1) is obtained by polymerizing an aromatic vinyl compound alone, and the block component (B-2) is obtained by polymerizing a conjugated diene compound alone. 3) is obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound. Here, examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, p- Examples thereof include tert-butyl-α-methylstyrene and p-tert-butylstyrene. These aromatic vinyl compounds may be used alone or in combination of two or more. On the other hand, examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and cyclopentadiene. These conjugated diene compounds may be used alone or in combination of two or more. Among the aromatic vinyl compounds, styrene is particularly preferable, and among the conjugated diene compounds, 1,3-butadiene, isoprene and cyclopentadiene are particularly preferable.

  The low molecular weight polymer (B) requires that the aromatic vinyl compound block has a peak molecular weight in terms of polystyrene of 1,000 or more, preferably 2,000 or more, and more preferably 5,000 or more. Here, if the peak molecular weight in terms of polystyrene of the aromatic vinyl compound block is 1,000 or more, the degree of polymerization of the aromatic vinyl compound block is sufficiently secured, and the effect of improving the fracture resistance is excellent.

  The low molecular weight polymer (B) preferably has a polystyrene-converted weight average molecular weight (Mw) of the aromatic vinyl compound block of 800 to 40,000, more preferably 800 to 30,000. If the polystyrene-equivalent weight average molecular weight (Mw) is less than 800, the effect of improving fracture characteristics and hysteresis loss cannot be obtained sufficiently. On the other hand, if it exceeds 40,000, the storage elastic modulus (G ′) at low temperature becomes too high. Low temperature characteristics such as brake performance at low temperatures and low temperature operability may be deteriorated.

  Furthermore, if the low molecular weight polymer (B) is subjected to ozonolysis, only the unsaturated bond of the conjugated diene compound portion is cleaved, so that the peak molecular weight, weight average molecular weight (Mw) and molecular weight distribution of the aromatic vinyl compound block ( Mw / Mn) can be measured. Here, as the “ozonolysis”, for example, the method described in Polymer Science Society Proceedings Vol. 29, No. 9, p. The “molecular weight distribution” is a ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).

  In the low molecular weight polymer (B), the vinyl bond content of the conjugated diene compound portion is preferably less than 30%, and more preferably less than 15%. When the vinyl bond content of the conjugated diene compound portion of the low molecular weight polymer (B) is 30% or more, the glass transition temperature (Tg) of the low molecular weight polymer (B) tends to increase, and the storage elastic modulus at a low temperature. (G ′) may rise and lower the low temperature characteristics.

  In the low molecular weight polymer (B), the block component (B-3) of the aromatic vinyl compound and the conjugated diene compound preferably has a bond amount of the aromatic vinyl compound of 5 to 90% by mass, It is more preferable that it is 80 mass%, and it is still more preferable that it is 10-70 mass%. If the bond amount of the aromatic vinyl compound is out of the specified range, suppression of microphase separation and sufficient compatibility with the high molecular weight polymer (A) may not be achieved.

  In the low molecular weight polymer (B), the mass ratio (X / Y) of the bond amount (X) of the aromatic vinyl compound and the bond amount (Y) of the conjugated diene compound is 5/95 to 95/5. It is preferably 10/90 to 90/10.

  The low molecular weight polymer (B) can be produced, for example, by sequentially polymerizing each block component forming the low molecular weight polymer (B) according to the sequence while controlling the composition ratio of the monomers to be polymerized. it can. For example, when the low molecular weight polymer (B) has a structure of (B-1)-(B-2)-(B-3) type, ether or tertiary amine or the like in a hydrocarbon solvent In the presence of a polar compound, an organic alkali metal is used as a polymerization initiator to initiate polymerization of the first monomer, and the polymerization conversion of the first monomer is less than 100% by mass, preferably 70 to 90% by mass. The block reaction (B-1) is carried out by carrying out a polymerization reaction until it falls within the range, then the second monomer is added, and the polymerization conversion of the second monomer is less than 100% by mass, preferably 70 to 90%. The block component (B-2) is produced by polymerization until the mass% range is reached, and finally the third monomer is added and further polymerized to produce the block component (B-3). From the viewpoint of improving low temperature characteristics and fracture resistance, it is preferable to form the block component (B-3) at the end of the polymerization reaction, and from the viewpoint of improving grip performance, at the beginning of the polymerization reaction. It is preferable to form the block component (B-1).

  In addition, according to the present invention, since the compatibility with the high molecular weight polymer (B) can be greatly improved by forming a tapered structure in the low molecular weight polymer (B), the tapered structure is surely obtained. It is preferable to produce the low molecular weight polymer (B) by the production method to be formed. Specifically, as described above, (a) a method in which the following monomer is added in a state where the polymerization conversion rate of the monomer in the polymerization solution is less than 100% by mass, and (b) the monomer is continuously added. In the polymerization reaction to be added, as the polymerization time elapses, a method of changing the composition ratio (for example, molar ratio, mass ratio, etc.) of the added monomer, and (c) adjusting the concentration of the randomizer used in the polymerization solution. And the like.

  The hydrocarbon solvent used for the production of the low molecular weight polymer (B) is not particularly limited, and cycloaliphatic hydrocarbons such as cyclohexane, methylcyclopentane, and cyclooctane, propane, butane, pentane, hexane, heptane, Aliphatic hydrocarbons such as octane and decane, aromatic hydrocarbons such as benzene, toluene, and ethylbenzene can be used. These hydrocarbons may be used alone or in combination of two or more.

  The organic alkali metal is preferably an organic lithium compound. Examples of the organic lithium compound include alkyl compounds such as ethyl lithium, propyl lithium, n-butyl lithium, sec-butyl lithium (sec-BuLi), and t-butyl lithium. Lithium; aryl lithium such as phenyl lithium and tolyl lithium; alkenyl lithium such as vinyl lithium and propenyl lithium; alkylene dilithium such as tetramethylene dilithium, pentamethylene dilithium, hexamethylene dilithium and decamethylene dilithium; 1,3 Other than allylene dilithium such as 1-dilithiobenzene and 1,4-dilithiobenzene; 1,3,5-trilithiocyclohexane, 1,2,5-trilithionaphthalene, 1,3,5,8-tetralithio Decane, 1,2,3,5-tetralithio-4-hexyl-ant Examples include helix. Among these, n-butyllithium, sec-butyllithium, t-butyllithium and tetramethylenedilithium are preferable, and n-butyllithium is particularly preferable. Furthermore, as the lithium-based polymerization initiator, a compound (DiLi) of sec-BuLi and m-diisopropenylbenzene can be used according to Macromolecules, vol. 27, 5957-5963 (1994). The amount of the organic alkali metal used is determined by the polymerization rate in the reaction operation and the molecular weight of the polymer to be produced, and is usually preferably in the range of 0.02 to 5 mg, more preferably in the range of 0.05 to 2 mg as metal atoms per 100 g of monomer. preferable. An organic alkali metal containing at least one metal selected from the group consisting of Co, Ni, Ti and Nd can also be used as the polymerization initiator.

  Moreover, you may implement the polymerization reaction of the said low molecular weight polymer (B) in presence of a randomizer. The randomizer can control the microstructure of the conjugated diene compound portion of the polymer. More specifically, the randomizer can control the amount of vinyl bonds in the conjugated diene compound portion of the polymer, or can control the conjugated diene content in the polymer. It has the effect of randomizing the compound unit and the aromatic vinyl compound unit. In particular, when the concentration of the randomizer in the polymerization solution is low, the reaction rate of the polymerization reaction is reduced, so that a tapered structure is naturally formed in the low molecular weight polymer (B). The randomizer includes dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine. 1,2-dipiperidinoethane, potassium-t-amylate, potassium-t-butoxide, sodium-t-amylate and the like.

  The polymerization reaction for obtaining the polymer (B) can be performed by either a batch polymerization method or a continuous polymerization method. The polymerization temperature in the polymerization reaction is preferably in the range of 0 to 130 ° C. The polymerization reaction can be carried out by any polymerization method such as isothermal polymerization, temperature rising polymerization and adiabatic polymerization. Furthermore, when performing the polymerization, an allene compound such as 1,2-butadiene may be added in order to prevent the formation of a gel in the reaction vessel.

  In the rubber composition of this invention, it is preferable to mix | blend the said low molecular weight polymer (B) in 2-100 masses with respect to 100 mass parts of said rubber components. If the blending amount of the low molecular weight polymer (B) with respect to 100 parts by mass of the rubber component is less than 2 parts by mass, the grip performance of the tire cannot be sufficiently improved, whereas if it exceeds 100 parts by mass, the rubber composition Mooney viscosity becomes too low, and productivity deteriorates. The blending amount of the low molecular weight polymer (B) with respect to 100 parts by mass of the rubber component is more preferably in the range of 5 to 80 parts by mass, and still more preferably in the range of 10 to 80 parts by mass.

  The rubber composition of the present invention preferably contains 10 to 200 parts by mass of a filler with respect to 100 parts by mass of the rubber component. When the blending amount of the filler with respect to 100 parts by mass of the rubber component is less than 10 parts by mass, sufficient fracture characteristics and the like cannot be obtained, while when it exceeds 200 parts by mass, the workability of the rubber composition is lowered. Further, the blending amount of the filler with respect to 100 parts by mass of the rubber component is more preferably in the range of 30 to 200 parts by mass, and further preferably in the range of 30 to 180 parts by mass. Here, as the filler, carbon black and inorganic filler are preferable. Moreover, a filler may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The carbon black is not particularly limited, and examples thereof include FEF, SRF, HAF, ISAF, and SAF grades. The carbon black is preferably carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or more. By blending carbon black, various physical properties of the rubber composition can be improved, but those of HAF, ISAF, and SAF grades are more preferable from the viewpoint of improving the wear resistance.

Examples of the inorganic filler include silica; alumina such as γ-alumina and α-alumina (Al ₂ O ₃ ); alumina monohydrate such as boehmite and diaspore (Al ₂ O ₃ .H ₂ O); gibbsite, buyer Aluminum hydroxide [Al (OH) ₃ ] such as Wright; aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ), Talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [ Ca (OH) _2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 ), Pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · 5H ₂ O), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium silicate Calcium (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ .nH ₂ O], zirconium carbonate [Zr (CO ₃ ) ₂ ], and various zeolites And crystalline aluminosilicate containing hydrogen, alkali metal, or alkaline earth metal that corrects the charge. Among these inorganic fillers, silica is particularly preferable, and specific examples include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate.

  In the rubber composition of the present invention, softening agents such as paraffin oil, naphthenic oil and aroma oil may be used as a softening component. The content of the softening agent is not particularly limited.

  The rubber composition of the present invention includes a rubber component containing the high molecular weight polymer (A), a low molecular weight polymer (B), a filler, a softener, a compounding agent usually used in the rubber industry, For example, an antioxidant, a silane coupling agent, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization agent, and the like can be appropriately selected and blended within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition of the present invention is produced by blending the above rubber component with the low molecular weight polymer (B) and various compounding agents appropriately selected as necessary, kneading, heating, extruding and the like. can do.

  The tire of the present invention is characterized by using the rubber composition as a tire member, and examples of the tire member include a tire tread, an under tread, a carcass, a sidewall, a bead portion, and the like. The tire of the present invention is obtained by forming each tire member using the rubber composition in an unvulcanized state, forming a raw tire according to a conventional method, and vulcanizing the raw tire. A tire in which the rubber composition is applied to any tire member is excellent in grip performance and fracture resistance. Moreover, as gas with which this tire is filled, inert gas, such as nitrogen, argon, helium other than normal or the air which adjusted oxygen partial pressure, can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  The polymer (X-1) and the polymers (Y-1) to (Y-12) were synthesized by the following method, and the styrene bond amount, vinyl bond amount, and weight average molecular weight of the obtained polymer were determined by the following method. Measured with Further, for the polymers (Y-1) to (Y-12), the molecular weight distribution and the weight average molecular weight of the aromatic vinyl compound block after ozonolysis were further measured by the following methods.

(1) Styrene bond amount The styrene bond amount of the synthesized polymer was calculated from the integral ratio of the ¹ H-NMR spectrum.

(2) Vinyl bond amount The vinyl bond amount of the butadiene part or isoprene part of the synthesized polymer was analyzed by an infrared method.

(3) Weight average molecular weight in terms of polystyrene (Mw)
The weight average molecular weight in terms of polystyrene of the synthesized polymer was measured by GPC. Here, 244 type GPC manufactured by Waters is used as GPC, a differential refractometer is used as a detector, columns GMH-3, GMH-6, and G6000H-6 manufactured by Tosoh are used as columns, and tetrahydrofuran is used as a mobile phase. Was used. In addition, using a monodisperse styrene polymer manufactured by Waters as a standard substance, a calibration curve was prepared by previously obtaining the relationship between the molecular weight of the monodisperse styrene polymer peak by GPC and the GPC count number, and using this, The molecular weight of the polymer in terms of polystyrene was determined.

(4) Peak molecular weight, molecular weight distribution (Mw / Mn) and weight average molecular weight (Mw)
The polymer is subjected to ozonolysis according to the method described in Proceedings of the Society of Polymer Science, Vol. 29, No. 9, p. Mw / Mn) and weight average molecular weight (Mw) were determined.

<Synthesis of polymer (X-1)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 12 g, 1,3-butadiene 200 g and styrene 100 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, in accordance with Macromolecules, vol.27, 5957-5963 (1994) as a polymerization initiator, 0.14 g of a compound (DiLi) of sec-BuLi and m-diisopropenylbenzene was added, and the monomer conversion rate under the temperature rising condition Polymerized until 99%. Thereafter, 3.5 g of 2,6-di-t-butyl-p-cresol was added as an anti-aging agent to obtain a polymer (X-1). The polymer (X-1) had a styrene bond content of 33% by mass, a vinyl bond content of 35%, and a polystyrene equivalent weight average molecular weight (Mw) of 400,000.

<Synthesis of polymer (Y-1)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 12 g, 1,3-butadiene 200 g and styrene 100 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.25 g of n-butyllithium was added and polymerized for 60 minutes under elevated temperature conditions. After confirming that the monomer conversion was 99%, 1 g of isopropyl alcohol was added to terminate the polymerization, and the polymer (Y-1) was obtained. The analytical values are shown in Table 1.

<Synthesis of polymer (Y-2)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 12 g, and styrene 50 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.25 g of n-butyllithium was added and polymerized for 60 minutes under elevated temperature conditions, 200 g of 1,3-butadiene was further polymerized for 60 minutes, and then 50 g of styrene was added to proceed the polymerization. Thereafter, after confirming that the monomer conversion rate was 99%, 1 g of isopropyl alcohol was added to terminate the polymerization, and a polymer (Y-2) was obtained. The analytical values are shown in Table 1.

<Synthesis of polymer (Y-3)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 14.4 g, styrene 65 g and 1,3-butadiene 55 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.5 g of n-butyllithium is added and polymerized for 60 minutes under elevated temperature conditions, 90 g of 1,3-butadiene is further polymerized for 60 minutes, and then 65 g of styrene and 55 g of 1,3-butadiene are added. Polymerization was allowed to proceed. Thereafter, after confirming that the conversion rate of the monomer reached 99%, 1 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-3). The analytical values are shown in Table 1.

<Synthesis of polymer (Y-4)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 14.4 g and styrene 120 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.5 g of n-butyllithium was added and polymerized for 300 minutes under the temperature rising condition, and 180 g of 1,3-butadiene was further added to proceed the polymerization. Thereafter, after confirming that the monomer conversion rate was 99%, 1 g of isopropyl alcohol was added to terminate the polymerization, and a polymer (Y-4) was obtained. The analytical values are shown in Table 1.

<Synthesis of polymer (Y-5)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 12 g, and styrene 90 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.25 g of n-butyllithium is added and polymerized under elevated temperature conditions for 60 minutes, 120 g of 1,3-butadiene is further added and polymerized for 60 minutes, and then 13.5 g of styrene and 76.5 g of 1,3-butadiene are added. In addition, the polymerization was allowed to proceed. Thereafter, after confirming that the conversion rate of the monomer reached 99%, 1 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-5). The analytical values are shown in Table 1.

<Synthesis of polymer (Y-6)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 12 g, styrene 13.5 g and 1,3-butadiene 76.5 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.25 g of n-butyllithium was added and polymerized for 60 minutes under elevated temperature conditions, 120 g of 1,3-butadiene was further added for polymerization for 60 minutes, and then 90 g of styrene was added to proceed the polymerization. Thereafter, after confirming that the conversion rate of the monomer reached 99%, 1 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-6). The analytical values are shown in Table 1.

<Synthesis of polymer (Y-7)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 1.5 g, and styrene 90 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.5 g of n-butyllithium was added and polymerized for 200 minutes under elevated temperature conditions, and then 90 g of 1,3-butadiene was added for polymerization, followed by addition of 24 g of styrene and 96 g of 1,3-butadiene. Made progress. Thereafter, after confirming that the conversion rate of the monomer was 99%, 1 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-7). The analytical values are shown in Table 2.

<Synthesis of polymer (Y-8)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 1.5 g, styrene 24 g and 1,3-butadiene 96 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.5 g of n-butyllithium was added and polymerized for 200 minutes under the temperature-raising conditions, and then 90 g of 1,3-butadiene was further added for polymerization for 200 minutes, and then 90 g of styrene was added to proceed the polymerization. Thereafter, after confirming that the monomer conversion rate was 99%, 1 g of isopropyl alcohol was added to terminate the polymerization, and a polymer (Y-8) was obtained. The analytical values are shown in Table 2.

<Synthesis of polymer (Y-9)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 18 g, and styrene 120 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, 1.7 g of n-butyllithium was added and polymerized for 100 minutes under a temperature rising condition, and then 180 g of isoprene was further added to proceed the polymerization. Thereafter, after confirming that the conversion rate of the monomer was 99%, 1.5 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-9). The analytical values are shown in Table 2.

<Synthesis of polymer (Y-10)>
Cyclohexane 3000 g, tetrahydrofuran (THF) 18 g, and styrene 75 g were introduced into a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, and the temperature in the autoclave was adjusted to 21 ° C. Next, after adding 1.7 g of n-butyllithium and polymerizing for 100 minutes under a temperature rising condition, 120 g of isoprene was further added for polymerization for 60 minutes, and then 52.5 g of styrene and 52.5 g of isoprene were added to proceed the polymerization. . Thereafter, after confirming that the conversion rate of the monomer was 99%, 1.5 g of isopropyl alcohol was added to terminate the polymerization to obtain a polymer (Y-10). The analytical values are shown in Table 2.

<Synthesis of Polymers (Y-11) and (Y-12)>
Polymers (Y-11) and (Y-12) were synthesized in the same manner as the polymer (Y-10) except that the polymerization conditions shown in Table 3 were changed. The analysis values are shown in Table 3.

  Next, using the polymer (X-1) and the polymers (Y-1) to (Y-12), rubber compositions having the formulation shown in Tables 4 to 5 were prepared according to a conventional method, and vulcanized. The vulcanized rubber obtained as described above was evaluated for low temperature characteristics, grip performance and fracture resistance by the following methods. The results are shown in Tables 4-5.

(5) Low temperature characteristics Storage modulus (G ') of Comparative Example 1 was measured using a rheometrics mechanical spectrometer at a shear strain of 5%, a temperature of -20 ° C, and a frequency of 15 Hz. The index was expressed as 100. The smaller the index value, the better the low-temperature characteristics such as low-temperature operability and brake performance.

(6) Grip performance Using a Rheometrics mechanical spectrometer, tan δ was measured at a shear strain of 5%, a temperature of 60 ° C., and a frequency of 15 Hz. The larger the index value, the greater the hysteresis loss, the better the grip performance, and the better the steering stability.

(7) Fracture resistance A tensile test was performed at room temperature in accordance with JIS K 6301-1995, the tensile strength (Tb) of the vulcanized rubber composition was measured, and the tensile strength of Comparative Example 1 was taken as 100. displayed. The larger the index value, the better the fracture resistance.

* 1 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., “NOCRACK 6C”.
* 2 Di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller DM”.
* 3 Nt-Butyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller NS”.

  From the results shown in Table 4, a low molecular weight polymer comprising a block component (B-1), a block component (B-2) and a block component (B-3), wherein the block component (B-3) was introduced at the terminal. The rubber compositions of Examples 1 to 5 blended with (B) were the rubber composition of Comparative Example 1 in which the monomers were completely randomly polymerized, Comparative Example 2 having no terminal block component (B-3). Compared with the rubber composition of Comparative Example 3 comprising the rubber composition of 4 and 5, and the block component (B-2) and the block component (B-3), the low temperature characteristics, grip performance and fracture resistance can be improved. I understand.

  From the comparison of Examples 1 to 4, when the block component (B-3) was first formed in the production of the low molecular weight polymer (B), the low temperature characteristics and the fracture resistance were greatly improved. Thus, it is understood that when the block component (B-3) is finally introduced, the grip performance can be greatly improved.

In addition, the rubber composition of Comparative Example 6 in which the low molecular weight polymer (B) has a polystyrene equivalent weight average molecular weight of less than 2.0 × 10 ³ and the polystyrene equivalent peak molecular weight of the aromatic vinyl compound block is less than 1,000. It can be seen that the low-temperature characteristics and grip performance of the rubber composition of Comparative Example 7, in which the low molecular weight polymer (B) has a polystyrene equivalent weight average molecular weight exceeding 1.0 × 10 ⁵ , are low.

Claims (14)

An aromatic vinyl compound-conjugated diene compound copolymer or a conjugated diene compound polymer, comprising a high molecular weight polymer (A) having a polystyrene-equivalent weight average molecular weight of 2.0 × 10 ^{5 to} 3.0 × 10 ^6. In contrast,
An aromatic vinyl compound-conjugated diene compound copolymer having a polystyrene-reduced weight average molecular weight of 2.0 × 10 ^{3 to} 1.0 × 10 ⁵ , wherein the aromatic vinyl compound block component (B-1) is a conjugated diene compound block A low molecular weight polymer (B) comprising a component (B-2) and a block component (B-3) of an aromatic vinyl compound and a conjugated diene compound;
The low molecular weight polymer (B) has the block component (B-3) at least at one end of the low molecular weight polymer (B), and an aromatic vinyl compound block of the low molecular weight polymer (B). A rubber composition having a polystyrene equivalent peak molecular weight of 1000 or more.   2. The rubber composition according to claim 1, wherein the low molecular weight polymer (B) forms a structure of (B-1)-(B-2)-(B-3) type.   The rubber composition according to claim 1, wherein the aromatic vinyl compound block has a polystyrene-equivalent weight average molecular weight of 800 to 40,000.   2. The rubber composition according to claim 1, wherein the block component (B-3) has an aromatic vinyl compound bond amount of 5 to 90 mass%.   The rubber composition according to claim 1, wherein the low molecular weight polymer (B) has a vinyl bond content of a conjugated diene compound portion of less than 30% by mass.   The aromatic vinyl compound is styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, p-tert-butyl. The rubber composition according to claim 1, wherein the rubber composition is at least one selected from the group consisting of -α-methylstyrene and p-tert-butylstyrene.   The rubber composition according to claim 6, wherein the aromatic vinyl compound is styrene.   The rubber composition according to claim 1, wherein the conjugated diene compound is at least one selected from the group consisting of 1,3-butadiene, isoprene and cyclopentadiene.   2. The rubber composition according to claim 1, wherein the low molecular weight polymer (B) is obtained by sequentially polymerizing each block component in accordance with its arrangement while controlling a composition ratio of monomers to be polymerized. object.   In the low molecular weight polymer (B), the mass ratio (X / Y) of the bond amount (X) of the aromatic vinyl compound and the bond amount (Y) of the conjugated diene compound is 5/95 to 95/5. The rubber composition according to claim 1.   The rubber composition according to claim 1, wherein the amount of the low molecular weight polymer (B) is 2 to 100 parts by mass with respect to 100 parts by mass of the rubber component.   Furthermore, 10-200 mass parts of fillers are contained with respect to 100 mass parts of said rubber components, The rubber composition of Claim 1 characterized by the above-mentioned.   The rubber composition according to claim 12, wherein the filler is carbon black.   A tire comprising the rubber composition according to any one of claims 1 to 13 for any tire member.