JP2010215884A - Rubber composition for tire and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a tire having a low glass transition temperature, a low elastic modulus even in a cold district and excellent low fuel consumption properties and to provide the tire using the same. <P>SOLUTION: The rubber composition for the tire includes a rubber (A) which can be vulcanized, a branched rubber (B) having a high cis-structure except (A), and (C) a rubber reinforcement material. The branched rubber (B) having the high cis-structure has ≥80% 1,4-cis structure and a ratio (Tcp/ML<SB>1+4</SB>) of a 5% toluene solution viscosity (Tcp) to a Mooney viscosity (ML<SB>1+4</SB>) at 100°C of 0.5 to 2.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention applies a rubber reinforcing agent to a vulcanizable rubber and a branched rubber having a high cis structure other than the rubber, so that the glass transition temperature is low and it is low even in cold regions. The present invention relates to the manufacture of a rubber composition for a tire that maintains an elastic modulus and is excellent in fuel efficiency, and a tire using the same.

  In the pneumatic tire field where low temperature characteristics are important, studless tires are used, and a blend of natural rubber and polybutadiene is applied as the rubber component. In particular, in the tread portion of the tire, it is necessary to improve the low-temperature characteristics to provide flexibility and improve the characteristics on ice.

  In order to improve the characteristics on ice, it is necessary to increase the coefficient of friction with the road surface by increasing the flexibility of the rubber in the tread at a low temperature, particularly in the vicinity of −30 ° C. At low temperatures, the elastic modulus of the rubber increases, making it impossible to follow the unevenness of the road surface. Also, the frozen road surface has less surface unevenness than the normal road surface, so the energy dissipation that occurs between the rubber and the road surface (tanδ) Contributes to the performance on ice. It is necessary to increase the real contact area between the rubber and the road surface at a low temperature, and it is more important to lower the storage elastic modulus around −30 ° C. (lower elastic modulus). For example, the use of butadiene rubber or natural rubber, which is a polymer having a low glass transition temperature, and a large amount of a softening agent are added to the rubber composition to improve flexibility at low temperatures. In particular, high-cis butadiene rubber having a high cis content that lowers the glass transition temperature is used for butadiene rubber. However, the high-cis butadiene rubber has the property of crystallizing in a low temperature region around -10 to 0 ° C because the microstructure is more uniform. This crystallization remains after vulcanization and raises the storage elastic modulus around -30 ° C.

In order to solve the above problem, the low temperature characteristics are improved while maintaining the characteristics as a tire by applying natural rubber and a high cis butadiene rubber with a cis content suppressed to some extent (Reference 1).
Further, in Reference Document 2, low temperature characteristics and fracture characteristics are improved by appropriately blending brominated butyl rubber as a third component with natural rubber and polybutadiene.
Furthermore, in Reference Document 3, on-ice performance, wear resistance, and heat generation characteristics are achieved by using three rubber components obtained by adding natural rubber to a blend of polybutadiene that does not crystallize in a low temperature environment and polybutadiene that crystallizes. ing.

The object of the present invention is to provide a rubber composition for tires in cold regions, which is considered to be a particularly harsh environment, and further exhibits superior low temperature elastic properties and low fuel consumption effects that could not be achieved by the prior art. To provide tires.

JP2003-292676 JP2007-211180 JP2007-314605

By applying rubber reinforcement to vulcanizable rubber and other branched rubbers with high cis structure, it has a low glass transition temperature and low elasticity even in cold regions. A rubber composition for a tire excellent in fuel efficiency is provided. Furthermore, a tire using the tire rubber composition described above is provided.

The present invention relates to a rubber composition for tires, which is a vulcanizable rubber (A) and a branched rubber (B) having a high cis structure other than (A) and a rubber reinforcing agent (C). .

  The present invention also relates to the above rubber composition for tires, wherein the vulcanizable rubber (A) is natural rubber.

In the present invention, the branched rubber (B) having a high cis structure has a 1,4-cis structure of 80% or more, a 5% toluene solution viscosity (Tcp), and a Mooney viscosity at 100 ° C. (ML _{1 + 4} ). The ratio (Tcp / ML _{1 + 4} ) to the tire rubber composition is 0.5 to 2.0.

  The present invention also relates to the tire rubber composition, wherein the rubber reinforcing agent (C) is carbon black and / or silica.

  The present invention also relates to a tire characterized by using the tire rubber composition.

  A rubber composition for a tire having a low glass transition temperature, a low elastic modulus even in a cold region, and excellent fuel efficiency, and a tire using the rubber composition can be provided.

(A) Vulcanizable rubber The vulcanizable rubber used in the rubber composition according to the present invention is not particularly limited, and any known rubber can be used. Preferably, a diene rubber is used. Can do. For example, diene monomers such as natural rubber, butadiene rubber (BR), syndiotactic-1,2-polybutadiene (SPB) -containing butadiene rubber, SPB-containing natural rubber, isoprene rubber, butyl rubber, and chloroprene rubber. Polymer: Acrylonitrile-diene copolymer rubber such as acrylonitrile butadiene rubber (NBR), nitrile chloroprene rubber, and nitrile isoprene rubber; Styrene-diene copolymer rubber such as styrene butadiene rubber (SBR), styrene chloroprene rubber, and styrene isoprene rubber And ethylene propylene diene rubber (EPDM) and the like. Of these, butadiene rubber, syndiotactic-1,2-polybutadiene-containing butadiene rubber, acrylonitrile butadiene rubber, styrene-butadiene rubber, natural rubber, and isoprene rubber are preferred. These can be used alone or in combination of two or more.

  Moreover, a vulcanizing agent and a vulcanization accelerator can be added to the vulcanizable rubber (A). Examples of the vulcanizing agent include sulfur, a compound that generates sulfur by heating, an organic peroxide, a metal oxide such as magnesium oxide, a polyfunctional monomer, and a silanol compound. Examples of the compound that generates sulfur by heating include tetramethyl thiuram disulfide and tetraethyl thiuram disulfide.

  The amount of (A) to be blended is 20 to 90 parts by weight, more preferably 30 to 80 parts by weight, particularly preferably 40 to 70 parts by weight of vulcanizable rubber in 100 parts by weight of the total rubber. What to mix | blend is preferable. When blended, there are various physical properties (tensile strength, elongation, tear strength, compression set, etc.) necessary for the compression characteristics of the tire, and a rubber elastic material sufficient at low temperatures, which is characteristic in the present invention. Obtainable.

(B) Branched rubber having a high cis structure The branched rubber having a high cis structure is selected from rubbers other than those selected from the above-mentioned (A) vulcanizable rubber. The types include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), nitrile rubber (NBR), ethylene propylene rubber (EPM), chloroprene rubber (CR), Examples include butyl rubber, urethane rubber, acrylic rubber, and silicon rubber.

  Of these, butadiene rubber (BR) is particularly desirable.

Furthermore, the following two structures must be defined quantitatively as necessary conditions for a branched rubber having a high cis structure.
(1) High cis structure In other words, the rubber microstructure contains a cis structure, and the ratio is generally preferably 80% or more, more preferably 88.0% to 99.8%, and 96.0 to 99.0%. More preferably, 95.0 to 98.9% is particularly preferable.
(2) The ratio (Tcp / ML _{1 + 4} ) of 5% toluene solution viscosity (Tcp) and Mooney viscosity (ML _{1 + 4} ), which is an index indicating the degree of branching of the branched structure molecule, is preferably 0.5 to 2.0, More preferably, it is 0.7-1.8, Most preferably, it is 0.8-1.5.
Tcp indicates the degree of molecular entanglement in the concentrated solution. In the case of high cis rubber having the same molecular weight distribution, the degree of branching is the same if the molecular weight is the same (ie, ML _{1 + 4} is the same). (The larger Tcp, the smaller the branching degree). Moreover, (the larger Tcp / _{ML 1 + 4,} degree of branching is small) index when Tcp / _{ML 1 + 4} is for comparing the degree of branching of different height Shisugomu of _{ML 1 + 4} is used as a.
In other words, the smaller the value of Tcp / ML _{1 + 4} , the more branched.

If Tcp / ML _{1 + 4} is larger than the above range, the problem of low-temperature crystallization is likely to occur. Conversely, if Tcp / ML _{1 + 4} is smaller than the above range, the problem of deterioration in fracture characteristics is likely to occur.

  Further, the molecular weight distribution (Mw / Mn) is preferably 1.5 to 9.0, more preferably 2.0 to 5.0, and particularly preferably 2.5 to 4.0.

  If the value of the molecular weight distribution is less than 1.5, the processability deteriorates, which is not preferable. On the other hand, if it is larger than 9.0, it is not preferable because the destructive property is deteriorated.

Furthermore, ML _{1 + 4} at 100 ° C. is preferably 30 to 60, more preferably 35 to 55, and particularly preferably 37 to 50. If the value is smaller than this value, the physical properties of rubber such as fracture characteristics tend to be lowered. Furthermore, it is a requirement that the gel content is not substantially contained.

  The amount of (B) to be blended is preferably 3 to 90 parts by weight, more preferably 5 to 80 parts by weight, and particularly preferably 7 to 70 parts by weight based on 100 parts by weight of the total rubber. When blended, various physical properties (tensile strength, elongation, tear strength, compression set, etc.) necessary for compression characteristics are obtained, and sufficient rubber elastic material is obtained at a low temperature characteristic of the present invention. Can do.

(C) Rubber reinforcing agent Examples of the rubber reinforcing agent (C) blended in the rubber composition according to the present invention include various carbon blacks, white carbon, silica, activated calcium carbonate, and ultrafine magnesium silicate. It is done. Among these, at least one of carbon black and silica is preferable. In particular, the combined use of carbon black and silica is preferable because it can bring out the mutual characteristics of both. Among the above carbon blacks, carbon black having a particle diameter of 90 nm or less and a dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more, for example, FEF, FF, GPF, SAF, ISAF, SRF, HAF, etc. Is used.

  Silica preferably has a silica purity of 97% or more. Silica having a purity of less than 97% does not have a sufficient rubber reinforcing effect, so that a rubber composition blended with such silica does not have sufficient wear resistance. The average particle diameter of the silica particles is preferably in the range of 0.1 to 50 μ, more preferably 1 to 50 μ, and particularly preferably 5 to 50 μ. Such silica particles can be obtained, for example, by a method of pulverizing completely melted quartz glass to an appropriate particle size. Further, pulverized natural quartz having a silica purity of 97% or more is also preferably used. Furthermore, particles obtained by hydrolyzing an organosilicon compound such as silane are also preferably used.

  A coupling agent may be used so that the vulcanizable rubber (A) and the branched rubber (B) having a high cis structure other than (A) and silica are well mixed. As the coupling agent, an alkylphenol formaldehyde resin initial condensate, an acid anhydride, a silane coupling agent, and a titanate coupling agent are preferable, and a silane coupling agent is more preferable.

  Examples of silane coupling agents include alkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, diethoxydiethylsilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, dimethoxymethylphenylsilane, triethoxyethylsilane, and trimethoxyphenylsilane. , Trimethoxypropylsilane, phenyltriethoxysilane, hexyltrimethoxysilane, octadecyltriethoxysilane, octadecyltrimethoxysilane, and N-dodecyltriethoxysilane.

  Including alkoxysilanes as described above, alkoxysilanes containing vinyl groups, alkoxysilanes having ester bonds, alkoxysilanes having epoxy groups, alkoxysilanes having amino groups, alkoxysilanes having mercapto groups, sulfide groups Examples include alkoxysilanes having chloro groups, alkoxysilanes having chloro groups, alkoxysilanes having styryl groups, alkoxysilanes having ureido groups, alkoxysilanes having isocyanate groups, and the like.

  Examples of alkoxysilanes having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, diethoxymethylvinylsilane, vinylmethyldimethoxysilane, trichlorovinylsilane, allyltriethoxysilane, allyltrimethoxysilane, allyltrichlorosilane, and vinyltris. Alkoxysilanes having (2-methoxyethoxy) silaneacryloxy group or methacryloxy group, such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3- Methacryloxypropylmethyldiethoxysilane and 3-methacryloxypropylmethyldimethoxysilane.

  Examples of the alkoxysilanes having an ester bond include triacetoxymethylsilane and diacetoxydimethylsilane.

  Examples of alkoxysilanes having an epoxy group include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropyltriethoxysilane, and 3-glycol. Examples include cidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane.

  Examples of alkoxysilanes having an amino group include 3- (N-phenyl) aminopropyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl Examples include methyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, and N- (vinylbenzyl) -2-aminoethyl-3-aminopropyl.

  Examples of alkoxysilanes having a mercapto group include 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropylmethyldimethoxysilane.

  Examples of alkoxysilanes having a sulfide group include 3-octanoylthio-1-propyltriethoxysilane and bis (triethoxysilylpropyl) tetrasulfide.

  Examples of alkoxysilanes having a chloro group include chloromethyltriethoxysilane, 3-chloropropyldimethoxymethylsilane, 3-chloropropyltrichlorosilane, 3-chloropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3 -Chloropropyldimethoxymethylsilane, butyltrichlorosilane, chlorohexyltrichlorosilane, dodecaciltrichlorosilane, ethyltrichlorosilane, n-decyltrichlorosilane, n-octyltrichlorosilane, n-tetradecyltrichlorosilane, and phenyltrichlorosilane is there.

  Examples of alkoxysilanes having a styryl group include p-styryltrimethoxysilane.

  Examples of alkoxysilanes having a ureido group include 3-ureidopropyltriethoxysilane.

  Examples of alkoxysilanes having an isocyanate group include 3-isocyanatepropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, and tris- (3-trimethoxysilylpropyl) isocyanurate.

  A silane coupling agent may be used in combination of a plurality of the above compounds.

The amount of the silane coupling agent used is preferably 0.1 to 100 parts by weight, more preferably 1 to 50 parts by weight, particularly preferably 2 to 100 parts by weight with respect to 100 parts by weight of the vulcanizable rubber (A).
30 parts by weight.

In particular, an alkoxysilane having an amino group or an epoxy group is desirable.

  In addition, when a silane coupling agent having an amino group is used, it is effective for both a vulcanizable rubber such as SBR and a polyamide-based resin, and as a result, the compatibility between the two is activated. Since it increases, it is more preferable. Similarly, the same effect can be obtained with a silane coupling agent having an epoxy group.

  When carbon black and silica used for the rubber reinforcing agent (C) are mixed, it becomes possible to achieve both workability, low energy loss and wear, and the rubber reinforcing agent (C) is a mixture of carbon black and silica. It is preferable. In particular, the weight ratio of the carbon black / silica is preferably 90/10 to 5/95, more preferably 80/20 to 20/80, and particularly preferably 70/30 to 30/70. If the amount of silica is less than 10%, energy loss increases, and if it is more than 90%, there is a drawback that workability and wear resistance are deteriorated.

  The amount of rubber reinforcing agent (C) used is a binary of vulcanizable rubber (A) and branched rubber (B) having a high cis structure when carbon black and silica are mixed. The amount is 1 to 160 parts by weight, preferably 30 to 120 parts by weight, more preferably 35 to 90 parts by weight, and particularly preferably 40 to 70 parts by weight with respect to 100 parts by weight of the system rubber.

  If the rubber reinforcing agent (C) is used only as carbon black, the compounding amount is 100 parts by weight of the binary rubber of the vulcanizable rubber (A) and the branched rubber (B) having a high cis structure. On the other hand, it is 10 to 90 parts by weight, preferably 20 to 80 parts by weight, more preferably 30 to 70 parts by weight, and particularly preferably 40 to 60 parts by weight.

  Further, when the rubber reinforcing agent (C) is used only as silica, the blending amount is 100 parts by weight of the binary rubber of the vulcanizable rubber (A) and the branched rubber (B) having a high cis structure. 1 to 100 parts by weight, preferably 5 to 90 parts by weight, more preferably 10 to 80 parts by weight, and particularly preferably 20 to 70 parts by weight.

  Silica can be either wet silica or dry silica. Moreover, combined use is also possible.

  Examples of the vulcanization accelerator used in the present invention include aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, and xanthates. Tetramethylthiuram disulfide (TMTD), N-oxydiethylene-2-benzothiazolylsulfenamide (OBS), N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide (MBTS) 2-mercaptobenzothiazole (MBT), zinc di-n-butyldithiocarbide (ZnBDC), zinc dimethyldithiocarbide (ZnMDC), and the like.

  In addition, if necessary, known additives usually used in rubber compositions such as anti-aging agent, filler, process oil, zinc white, stearic acid and the like can be blended.

  Anti-aging agents include amine / ketone-based, imidazole-based, amine-based, phenol-based, sulfur-based and phosphorus-based anti-aging agents. More specifically, as an anti-aging agent, phenol-based 2,6-di-tert-butyl-p-cresol (BHT), phosphorus-based trinonylphenyl phosphite (TNP), sulfur-based 4.6-bis (Octylthiomethyl) -o-cresol, dilauryl-3,3′-thiodipropionate (TPL) and the like.

  Fillers include inorganic fillers such as calcium carbonate, basic magnesium carbonate, clay, Lissajous, and diatomaceous earth, recycled fillers, and fillers such as powdered rubber. Process oils include aromatics, Examples include naphthenic and paraffinic process oils.

  As the vulcanization aid, known vulcanization aids such as aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, and xanthates are used.

  As the scorch inhibitor (retarder), organic acids, nitroso compounds, N-cyclohexylthiophthalimide, sulfonamide derivatives, and the like are used.

  Examples of the anti-aging agent include amine / ketone series, imidazole series, amine series, phenol series, sulfur series and phosphorus series.

  Examples of the filler include inorganic fillers such as calcium carbonate, basic magnesium carbonate, clay, Lissajous and diatomaceous earth, and organic fillers such as recycled rubber and powder rubber.

  The process oil may be any of aromatic, naphthenic, and paraffinic.

As long as the object of the present invention is not impaired, various chemicals usually used in the rubber industry, for example, vulcanizing agents, vulcanization accelerators, process oils, scorch preventing agents, zinc white, stearic acid and the like are included as desired. Can be made.

  (A) A vulcanizable rubber and a branched rubber (B) having a high cis structure other than (A) and (C) a rubber reinforcing agent are used for closed kneading such as an open kneader such as a roll or a Banbury mixer. It can be obtained by kneading using a kneader such as a machine, vulcanized after molding, and applied to various rubber products.

  In the present invention, the blending ratio of the vulcanizable rubber (A) and the rubber reinforced (C) having a high cis structure other than the vulcanizable rubber (A), which is a constituent element of the invention, is appropriately changed. Thus, excellent characteristics can be exhibited for the tire member of the rubber composition for base tread, the rubber composition for sidewall, and the rubber composition for chafer. Specifically, the invention is as follows.

(1) Rubber composition for base tread Rubber reinforcing agent (C) 20 to 70 per 100 parts by weight of vulcanizable rubber (A) and branched rubber (B) having a high cis structure other than (A) The rubber reinforcing agent (C) contains at least carbon black and silica, and the blending amount of silica in the rubber reinforcing agent (C) is 80% by mass or less. The present inventors have found that a rubber composition for base tread having a large elongation at break, excellent exothermic property and fatigue, and excellent balance between them can be obtained.

  That is, in the present invention, 20 to 70 parts by mass of the rubber reinforcing agent (C) is added to 100 parts by weight of the vulcanizable rubber (A) and the branched rubber (B) having a high cis structure other than (A). And a rubber composition for base tread, wherein the rubber reinforcing agent (C) contains at least carbon black and silica, and the amount of silica in the rubber reinforcing agent (C) is 80% by mass or less. . Moreover, this invention is a base tread containing the said rubber composition for base treads. Furthermore, this invention is tires, such as a tire for passenger cars and a studless tire, which have the said base tread.

(2) Rubber composition for chafer rubber vulcanizable rubber (A) and branched rubber (B) having a high cis structure other than (A) 100 parts by weight of rubber reinforcing agent (C) 60-100 Containing parts by weight, JIS-A hardness is 70 to 90, and elongation at break in tensile test is 180% or more, exothermic property, elongation at break, hardness and fatigue properties are excellent, and their balance is excellent It has been found that a rubber composition for a chafer can be obtained.

  That is, in the present invention, 60 to 100 parts by weight of the rubber reinforcing agent (C) is added to 100 parts by weight of the vulcanizable rubber (A) and the branched rubber (B) having a high cis structure other than (A). It is a rubber composition for chafers containing JIS-A hardness of 70 to 90 and elongation at break in a tensile test of 180% or more. Moreover, this invention is a chafer containing the said rubber composition for chafers. Furthermore, this invention is tires, such as a tire for passenger cars and a studless tire which have the said chafer.

(3) Rubber composition for side wall Rubber reinforcing agent (C) 20-60 with respect to 100 parts by weight of vulcanizable rubber (A) and branched rubber (B) having a high cis structure other than (A) Sidewall rubber that contains parts by weight and has excellent heat generation, chip cut resistance, hardness, fatigue, and flex crack growth by having a JIS-A hardness of 55 to 75, and excellent balance between them. It has been found that a composition can be obtained.

  That is, the present invention contains 20 to 60 parts by weight of a rubber reinforcing agent (C) with respect to 100 parts by weight of a vulcanizable rubber (A) and a branched rubber (B) having a high cis structure other than (A). And a rubber composition for a sidewall, having a JIS-A hardness of 55 to 75. Moreover, this invention is a side wall containing the said rubber composition for side walls. Furthermore, this invention is tires, such as a tire for passenger cars and a studless tire which have the said sidewall.

From Table 1, all the examples of the present invention are compared with Comparative Example 1 which is a binary rubber configuration of (A) a vulcanizable rubber and a branched rubber having a high cis structure other than (A). It can be seen that the elastic modulus at −30 ° C. is lowered. Furthermore, it can be seen that the crystallization temperatures are all lower than in the comparative example.
Therefore, the rubber composition in which the rubber reinforcing agent is added to the binary rubber of the present invention shows improvement in rubber elasticity at a low temperature, suggesting that an excellent tire rubber can be provided.

  (A) A vulcanizable rubber and a branched rubber (B) having a high cis structure other than (A) and (C) a rubber reinforcing agent are used for closed kneading such as an open kneader such as a roll or a Banbury mixer. It can be obtained by kneading using a kneader such as a machine, vulcanized after molding, and applied to various rubber products.

  From Table 1, all the examples of the present invention are as follows: Comparative Example 1 which is a binary rubber composition of (A) a vulcanizable rubber and a linear rubber having a high cis structure other than (A). Compared with it, it turns out that the elasticity modulus in -30 degreeC is falling. Furthermore, it can be seen that the crystallization temperatures are all lower than in the comparative example. Therefore, it shows good tire performance at low temperatures.

(Tensile modulus)
The tensile modulus M100 was measured according to JIS K6251. The index was calculated with a comparative example of 100. The larger the value, the higher the tensile stress.

(Molecular weight measurement)
The molecular weight and molecular weight distribution were calculated using a standard polystyrene calibration curve using two columns in series using HLC-8220 GPC manufactured by Tosoh Corporation. The column used was Shodex GPC KF-805L column, which was measured by measuring a column temperature of 40 ° C. in THF.

(Differential calorimeter (DSC)
The measurement was performed under a nitrogen atmosphere using a differential calorimeter (DSC). The temperature was raised from 30 ° C to 100 ° C at 10 ° C / min, held at 100 ° C for 10 minutes, and then immediately measured for crystallization from 100 ° C to -70 ° C at a rate of 5 ° C / min. did.

(Mooney viscosity measurement)
The Mooney viscosity (ML _{1 + 4} , 100 ° C.) measurement was performed in accordance with JIS K-6300 standard.

(Vulcanization speed)
The vulcanization speed was measured in accordance with JIS K-6300 standard, and the time required to reach 90% vulcanization degree was measured using JSR Clastometer 2F type.

[Vulcanized physical properties]
(hardness)
The hardness was measured according to a measurement method defined in JIS-K6253.

(Tensile stress)
Tensile stress measured 100% tensile stress according to JIS-K6251. The larger the value, the higher the tensile stress.

(Tensile strength)
For the tensile strength, the tensile strength at break was measured according to JIS-K6251. It shows that it is so favorable that a numerical value is large.

(Elongation at break)
The elongation at break was determined by measuring the elongation at break according to JIS-K6251. It shows that it is so favorable that a numerical value is large.

(Rebound resilience)
The rebound resilience was measured at 23 ° C. according to JIS-K6255. The larger the value, the better the resilience.

(Low fuel consumption (heat generation))
It measured according to the measuring method prescribed | regulated to JISK6265. PS (%) was shown as compression set at the time of dynamic change, and the temperature rise after 25 minutes at a start temperature of 100 ° C. was shown as ΔT. The index was calculated using a comparative example of 100. A larger index indicates better physical properties.

(Low fuel consumption of vulcanizate (tan δ))
Using an EPLEXOR 100N manufactured by GABO, measurement was performed under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, and a dynamic strain of 0.3%. The larger the index, the better.

(Crystallization temperature)
The crystallization temperature was measured using an EPLEXOR 100N manufactured by GABO under the conditions of a temperature of −30 ° C., a frequency of 10 Hz, and a dynamic strain of 0.3%, and the rise in elastic modulus was obtained from the tangent line between two points. Using temperature, the lower the temperature, the better.

(Low temperature storage modulus)
The low temperature storage modulus (E '@-30 ° C) is measured using an EPLEXOR 100N manufactured by GABO under the conditions of a temperature of -30 ° C, a frequency of 10 Hz, and a dynamic strain of 0.3%. 100, and the larger the value, the lower the elastic modulus at −30 ° C. and the better.

(Rambourn wear evaluation)
Abrasion resistance: 4.5 kg load using a Lambourn Abrasion Tester, sand fall rate of about 15 g / min. The following slip ratio was tested. Slip rate: 20%, sample rotation speed 60 m / min. , Drum rotation speed 48 m / min. Slip rate: 60%, sample rotation speed 60 m / min, drum rotation speed 24 m / min. The amount of wear (cc / min) measured in (1) was obtained and evaluated as an index with a comparative example of 100. The higher the index, the better the wear resistance.

Examples are shown below.
(Example)
Production method of branched polybutadiene Dehydration treatment using molecular sieves in advance in a stainless steel reaction tank with a stirrer (stirring blade diameter 0.06m) with 1.5L (tank diameter 0.08m) substituted with nitrogen gas 1.0 L of the polymerized solution (1.3-butadiene: 30.0 wt%, cyclohexane: 70.0 wt%) was added. Next, under stirring at 400 rpm, water 1.4 mmol, diethylaluminum chloride 4.2 mmol, cyclooctadiene 11.5 mmol, and cobalt octoate 0.0087 mmol were added, and cis-1,4 polymerization was performed at 50 ° C. for 30 minutes. .
Ethanol containing 4,6-bis (octylthioethyl) -o-cresol was added thereto to terminate the polymerization, and then unreacted butadiene and 2-butenes were removed by evaporation to obtain 86 g of polybutadiene rubber.
This polymer had a Mooney viscosity (ML1 + 4) at 100 ° C. of 40.1 and a 5 wt% toluene solution viscosity (Tcp) at 25 ° C. of 55.2. The weight average molecular weight (Mw) was 450,000, the 1,4-cis structure content was 97.3%, and the intrinsic viscosity ([η]) was 1.9.
Using the above-mentioned branched polybutadiene, in accordance with the formulation shown in Table 2, using a 250 cc closed kneader, kneading natural rubber, branched polybutadiene, metallocene BR, carbon black, etc., and then adding the vulcanization accelerator and sulfur. Mixed with open roll. Next, press vulcanization was performed, and the physical properties were evaluated by the obtained vulcanized test pieces. The results are shown in Table 1.

(Comparative example)
According to the formulation shown in Table 2, a natural rubber, linear polybutadiene, carbon black and the like were kneaded using a 250 cc closed kneading apparatus, and then the vulcanization accelerator and sulfur were mixed with an open roll. Next, press vulcanization was performed, and the physical properties were evaluated by the obtained vulcanized test pieces.

The materials applied in this experiment are as follows.
Natural rubber: RSS # 1 (ML1 + 4, 100 ° C = natural rubber adjusted to 70)
Linear high cis polybutadiene: UBEPOL BR150L manufactured by Ube Industries, Ltd.
Branched high cis polybutadiene: UBEPOL BR150B manufactured by Ube Industries, Ltd.
Carbon Black: Tokai Carbon Seast 9
Aroma oil: Esso Oil # 110
Stearic acid: Asahi Denka Adeka Fatty Acid SA-300
Zinc oxide: Sakai Chemical Industry Sazex No. 1 anti-aging agent: Era Ouchi Nocrack 6C
Vulcanization accelerator: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Sulfur manufactured by Hosoi Chemical Co., Ltd.

The use of the rubber composition obtained in the present invention is a tire field, in particular, a cold region tire. Further, as a tire member, it is a base tread, a sidewall, a chafer, a beat, a rim strip and the like.

Claims (5)

A rubber composition for tires, which is a vulcanizable rubber (A), a branched rubber (B) having a high cis structure other than (A), and a rubber reinforcing material (C).   2. The tire rubber composition according to claim 1, wherein the vulcanizable rubber (A) is natural rubber. The branched rubber (B) having a high cis structure has a 1,4-cis structure of 80% or more, a ratio of 5% toluene solution viscosity (Tcp) to Mooney viscosity (ML _{1 + 4} ) at 100 ° C. (Tcp / ML1 _{+ 4} ) is 0.5-2.0, The rubber composition for tires in any one of Claim 1 and 2 characterized by the above-mentioned.   The rubber composition for tires according to any one of claims 1 to 3, wherein the rubber reinforcing material (C) is carbon black and / or silica.   A tire produced using the tire rubber composition.