JP6521611B2 - Vulcanized rubber composition and tire using the same - Google Patents

Description

  The present invention relates to a vulcanized rubber composition and a tire having a tread constituted of the vulcanized rubber composition.

  Conventionally, the fuel consumption of a vehicle has been reduced by reducing the rolling resistance of the tire (i.e., improving the fuel consumption). The rolling resistance of the tire is largely dependent on the low heat buildup of the rubber used in the tire members, so development was carried out actively to realize the low heat buildup of the rubber, and further, it was adapted to lower fuel consumption Various formulations have been studied. In particular, in the filler, not only conventional carbon black but also silica which is advantageous for low fuel consumption is often used.

  On the other hand, as a method to improve various tire performances such as low fuel consumption performance, low temperature performance, performance on ice and snow, and wear resistance performance in a balanced manner, a method (polymer blend) of blending multiple polymer (rubber) components has long been practiced The Specifically, as rubber components in tires, it has become mainstream to blend some polymer components represented by styrene butadiene rubber (SBR), butadiene rubber (BR) and natural rubber (NR) . This is a means to bring out the physical properties of the vulcanized rubber composition which can not be achieved with a single polymer component by utilizing the characteristics of each polymer component.

  In this polymer blend, the phase structure (morphology) of each rubber component after being vulcanized and the distribution of fillers such as silica in each rubber phase (the uneven distribution of silica) are important factors that determine the physical properties. It becomes. The factors determining the control of morphology and filler uneven distribution are very complicated, and many studies have been made so far to achieve well-balanced expression of tire physical properties, but there is still room for improvement.

  For example, Patent Document 1 discloses a technology in which the island phase particle size and silica distribution of a sea-island matrix of a rubber composition for a tire tread containing styrene butadiene rubber are defined. However, as a specific method which can realize the morphology, it is only described that it was adjusted by the kneading time and the rotational torque of the rotor using a silica master batch, and in such a method, the kneading and vulcanization conditions are The morphology was largely influenced by this, and stable morphology control was difficult. Further, the rubber components disclosed in the examples are also those of styrene butadiene rubbers having relatively close polarity, and like the butadiene rubber and the natural rubber, the polarity, that is, between the rubber components having different affinity to silica. It is clear that this is an inapplicable technology in blending.

  Patent Document 2 discloses a technique for controlling the morphology and silica uneven distribution of a compounded system containing natural rubber and butadiene rubber, but only discloses the uneven distribution in the island phase, and the silica uneven distribution is disadvantageous. There is no description for silica uneven distribution control in butadiene rubber.

  Natural rubber is an important rubber component in tires, especially in rubber compositions for sidewalls, which has excellent mechanical strength, but when it is blended with butadiene rubber, it tends to cause uneven distribution of silica and controls the distribution of silica. Although it has been necessary to assemble the composition, conventionally there has been a case where sufficient morphology and the state of distribution of the silica have not been confirmed, and there is a case where the composition does not exhibit sufficient physical properties.

  Furthermore, in recent years, with the aim of improving fuel economy, there is also a tendency to perform modifications to improve the affinity to silica with natural rubber, and the possibility of uneven distribution of silica in natural rubber is becoming increasingly prominent.

  Also, in recent years, high cis butadiene rubber having excellent abrasion resistance and low temperature grip characteristics has often been compounded, but among diene rubbers, high cis butadiene rubber, especially with silica The affinity is low, and in the compounding system with natural rubber, high-cis butadiene rubber phase tends to be hardly incorporated with silica. Therefore, in the conventional high cis butadiene rubber compounding system, there is a case where the compounding is such that sufficient physical properties do not appear without the condition of morphology and silica distribution being confirmed.

  In particular, in rubber compositions for side walls, it is important to constitute a rubber composition with butadiene rubber having the performance required for side walls such as flex crack growth resistance as a continuous phase, and to wear resistance performance. The technology to control the uneven distribution of silica to the continuous phase rubber component with a large contribution is essential.

  Further, with regard to the degree of distribution of silica to each rubber phase, there is no one defined by the measurement result accurately reflecting the actual physical properties of the tire, and further study was necessary.

JP, 2006-089636, A JP, 2006-348222, A

  Then, an object of this invention is to provide the tire which has a vulcanized rubber composition which can improve abrasion resistance performance and low fuel consumption performance with sufficient balance, and a tire member using the same.

The present invention
[1] It has a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase),
BR phase and IR phase are mutually incompatible,
A vulcanized rubber composition in which the abundance ratio α of silica in the BR phase after vulcanization satisfies the following formula 1, and the proportion β of butadiene rubber satisfies the following formula 2,
0.3 ≦ α ≦ 0.7 (preferably 0.5 ≦ α ≦ 0.6) (Formula 1)
0.4 ≦ β ≦ 0.8 (preferably 0.5 ≦ β ≦ 0.7) (Formula 2)
(Here, α = amount of silica in BR phase / (amount of silica in BR phase + amount of silica in IR phase), β = mass of butadiene rubber in vulcanized rubber composition / (vulcanized rubber composition Mass of butadiene rubber + mass of isoprene rubber in the vulcanized rubber composition).
[2] The abundance ratio γ of silica to the ratio β of butadiene rubber satisfies the following formula 3;
The vulcanized rubber composition according to the above [1], wherein the dispersion ratio δ of the entire system satisfies the following formula 4;
0.6 ≦ γ ≦ 1.4 (preferably 0.8 ≦ γ ≦ 1.2) (Equation 3)
δ ≦ 0.8 (preferably δ ≦ 0.6) (Equation 4)
(Here, γ = α / β, and δ = inter-silica distance standard deviation / inter-silica average distance.)
[3] Vulcanization according to the above [1] or [2], comprising 15 to 120 parts by mass, preferably 50 to 100 parts by mass of silica based on 100 parts by mass of the rubber component containing butadiene rubber and isoprene rubber Rubber composition,
[4] The vulcanized rubber composition according to any one of the above [1] to [3], wherein the butadiene rubber is a butadiene rubber having a cis-1,4 bond content of 90% or more, preferably 95% or more.
[5] The filler is contained in an amount of 15 to 120 parts by mass, preferably 30 to 100 parts by mass, based on 100 parts by mass of the rubber component containing butadiene rubber and isoprene rubber. The vulcanized rubber composition according to any one of the above [1] to [4], which contains silica in an amount of not less than 70% by mass, preferably not less than 70% by mass.
[6] Any one of the above [1] to [5] containing 15 to 80 parts by mass, preferably 20 to 70 parts by mass of a softener per 100 parts by mass of a rubber component containing butadiene rubber and isoprene rubber The present invention relates to a tire having a vulcanized rubber composition as set forth in [7] and a tread made of the vulcanized rubber composition as set forth in any one of [1] to [6] above.

  According to the present invention, in an incompatible system having a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase), the abundance ratio of silica α in the BR phase and butadiene rubber Is a vulcanized rubber composition in which the ratio .beta. Is within a predetermined range, so it is possible to provide a tire in which the fuel economy and the abrasion resistance are improved in a well-balanced manner.

It is a figure which shows the SEM photograph of the cross section of the vulcanized rubber composition (a) in which the dispersion | distribution of a silica is favorable, and the vulcanized rubber composition (b) to which silica is unevenly distributed.

The vulcanized rubber composition of the present invention has a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase), and the BR phase and the IR phase are not in phase with each other. It is soluble, the abundance ratio α of silica in the BR phase after vulcanization satisfies the following equation 1, and the proportion β of butadiene rubber satisfies the following equation 2.
0.3 ≦ α ≦ 0.7 (Equation 1)
0.4 ≦ β ≦ 0.8 (Equation 2)
(Here, α = amount of silica in BR phase / (amount of silica in BR phase + amount of silica in IR phase), β = mass of butadiene rubber in vulcanized rubber composition / (vulcanized rubber composition Of the butadiene rubber in the vulcanized rubber composition and the mass of the butadiene rubber in the vulcanized rubber composition and the mass of the isoprene rubber in the vulcanized rubber composition are respectively It corresponds to the content of each rubber contained when producing a vulcanized rubber composition.)

  The dispersion state of silica in the rubber component of the vulcanized rubber composition can be observed by a scanning electron microscope (SEM). For example, in an example where the dispersion of silica according to one embodiment of the present invention is good, as shown in FIG. 1 (a), a phase (BR phase) 1 containing butadiene rubber forms a sea phase and an isoprene system A phase (IR phase) 2 containing rubber (natural rubber) forms an island phase, and silica 3 is dispersed in both BR phase 1 and IR phase 2. On the other hand, in the example where silica different from the embodiment of the present invention is unevenly distributed in one phase, as seen in (b) of FIG. 1, BR phase 1 corresponds to sea phase as in (a) of FIG. Although IR phase 2 forms an island phase, silica 3 is localized in IR phase 2 and is not dispersed in both phases.

  The vulcanized rubber composition of the present invention has a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase), and the BR phase and the IR phase are not in phase with each other. It is soluble. Here, in the present specification, "incompatible" means that the average equivalent circle radius of the non-continuous phase is, for example, 100 nm or more in the cross section of the vulcanized rubber composition, for example, a scanning electron microscope (SEM Can be easily evaluated by the image taken by

Further, in the vulcanized rubber composition of the present invention, when the abundance ratio α of silica in the BR phase satisfies the following formula 1, the abrasion resistance performance and the fuel consumption performance are improved. In the present specification, “the abundance ratio α of silica in the BR phase” is an index indicating how much of the total amount of silica in the vulcanized rubber composition is present in the BR phase after vulcanization.
0.3 ≦ α ≦ 0.7 (Equation 1)
(Here, α = the amount of silica in the BR phase / (the amount of silica in the BR phase + the amount of silica in the IR phase))

  Specifically, for example, a vulcanized rubber composition is surfaced and used as a sample. For scanning electron microscope (SEM) photographs of one sample, 10 regions of 2 μm × 2 μm not overlapping with each other are selected. In each region, the silica area per unit area and the silica area in the BR phase in the unit area are measured to calculate the silica abundance of the BR phase. If it can be confirmed that the difference between the maximum value and the minimum value of the 10 silica abundances is within 10%, then the average of the 10 silica abundances is taken as α.

  The abundance ratio α of silica in the BR phase is 0.3 or more, preferably 0.5 or more. When the abundance ratio α of silica in the BR phase is less than 0.3, the improvement of the wear resistance performance and the fuel consumption performance can not be expected, but tends to decrease. Further, the abundance ratio α of silica in the BR phase is 0.7 or less, preferably 0.6 or less. When the abundance ratio α of silica in the BR phase exceeds 0.7, in particular, the improvement of the wear resistance can not be expected, but tends to decrease.

In the vulcanized rubber composition of the present invention, the ratio β of butadiene rubber satisfies the following formula 2.
0.4 ≦ β ≦ 0.8 (Equation 2)
(Here, β = mass of butadiene rubber in vulcanized rubber composition / (mass of butadiene rubber in vulcanized rubber composition + mass of isoprene-based rubber in vulcanized rubber composition), vulcanized rubber The mass of butadiene rubber in the composition and the mass of isoprene-based rubber in the vulcanized rubber composition respectively correspond to the content of each rubber contained when producing the vulcanized rubber composition).

  The proportion β of butadiene rubber is 0.4 or more, preferably 0.5 or more. If the proportion β of butadiene rubber is less than 0.4, improvement of the fuel efficiency obtained can not be expected. Moreover, the ratio β of butadiene rubber is 0.8 or less, preferably 0.7 or less. When the proportion β of butadiene rubber exceeds 0.8, the content of isoprene-based rubber tends to be small, and sufficient breaking strength and abrasion resistance can not be obtained.

Furthermore, in the vulcanized rubber composition of the present invention, it is preferable that the abundance ratio γ of silica to the ratio β of butadiene rubbers satisfies the following formula 3.
0.6 ≦ γ ≦ 1.4 (Equation 3)
(Here, γ = α / β.)

  As used herein, "silica abundance γ" is the silica abundance in BR relative to butadiene rubber percentage β. In the case where silica is ideally distributed in the BR phase, the abundance ratio γ of silica is 1.

  The silica abundance ratio γ with respect to the butadiene rubber ratio β is preferably 0.6 or more, and more preferably 0.8 or more. By setting the silica abundance ratio γ to 0.6 or more with respect to the ratio β of butadiene rubber, the abrasion resistance performance and the fuel consumption performance tend to be improved. 1.4 or less is preferable and, as for the silica abundance (gamma) with respect to the ratio (beta) of butadiene rubber, 1.2 or less is more preferable. By setting the silica abundance ratio γ to be 1.4 or less with respect to the ratio β of butadiene rubber, the abrasion resistance performance and the fuel consumption performance tend to be improved.

In the vulcanized rubber composition of the present invention, it is preferable that the dispersion ratio δ of silica in the entire system satisfy the following formula 4.
δ ≦ 0.8 (Equation 4)
(Here, δ = inter-silica distance standard deviation / inter-silica average distance)

  As used herein, "average distance between silicas" is the distance between adjacent wall surfaces of silica aggregates. The silica aggregate is expanded to fill the image to create a pseudo- Voronoi polygon, and the inter-particle distance of particles adjacent to the pseudo- Voronoi polygon is measured. The inter-particle distance can be obtained by determining the distance between the point at which the particles are closest to each other. For example, it can be easily calculated using a commercially available program such as LUZEX (registered trademark) AP of Nireco Co., Ltd., using an image captured by a scanning electron microscope (SEM).

  0.8 or less is preferable and, as for dispersion ratio (delta) of the whole system, 0.6 or less is more preferable. By setting the dispersion ratio δ of the entire system to 0.8 or less, the silica tends to be dispersed in the entire system, and the physical properties tend to be improved. The dispersion ratio δ of silica is most preferably 0.

  The BR used in the present invention is not particularly limited. For example, BR having a cis 1, 4 bond content of less than 50% (low cis BR), BR having a cis 1, 4 bond content of 90% or more High cis BR), rare earth butadiene rubber synthesized with a rare earth catalyst (rare rare earth BR), BR containing syndiotactic polybutadiene crystals (SPB containing BR), modified BR (high cis modified BR, low cis modified BR) Etc. can be used. Among them, it is preferable to use at least one selected from the group consisting of high cis native BR, high cis modified BR, low cis native BR and low cis modified BR, and it is more preferable to use high cis native BR.

  Examples of the high cis BR include BR730 and BR51 manufactured by JSR Co., Ltd., BR1220 manufactured by Nippon Zeon Co., and BR130B, BR150B, BR710 manufactured by Ube Industries, Ltd., and the like. Among high-cis BR, those having a cis 1,4-bond content of 95% or more are more preferable. These may be used alone or in combination of two or more. Low temperature properties and wear resistance can be improved by containing high cis BR. Examples of the low-cis BR include BR1250 manufactured by Nippon Zeon Co., Ltd., and the like. These may be used alone or in combination of two or more.

  The modified BR is not particularly limited, but preferred is a modified BR having an alkoxyl group as a modifying group in BR, and the like, and a high cis modified BR is more preferred.

  The isoprene-based rubber used in the present invention is not particularly limited, and those generally used in the tire industry can be used, and examples thereof include natural rubbers such as SIR20, RSS # 3, and TSR20. The isoprene-based rubber of the present invention includes modified natural rubber, modified natural rubber, synthetic isoprene rubber, and modified synthetic isoprene rubber.

  The silica is not particularly limited, and for example, silica generally used in the tire industry such as silica (anhydrous silicic acid) prepared by a dry method or silica (hydrous silicic acid) prepared by a wet method is used can do.

Nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably not less than ^{70m 2 / g, 140m 2 /} g or more is more preferable. By setting the N ₂ SA of silica to 70 m ² / g or more, sufficient reinforcement can be obtained, and fracture strength and abrasion resistance can be made favorable. The N ₂ SA of the silica is preferably not more than 220 m ² / g, more preferably at most 200m ² / g. By setting the N ₂ SA of silica to 220 m ² / g or less, the dispersion of silica is facilitated, and the processability can be improved. Here, N ₂ SA of the silica in this specification is a value measured by the BET method in accordance with ASTM D3037-81.

  15 mass parts or more are preferable with respect to 100 mass parts of rubber components, and, as for content of a silica, 50 mass parts or more are more preferable. By setting the total content of silica to 15 parts by mass or more, abrasion resistance, fracture characteristics, and fuel economy tend to be good. Moreover, 120 mass parts or less are preferable with respect to 100 mass parts of rubber components, and, as for the total content of a silica, 100 mass parts or less are more preferable. By setting the total content of silica to 120 parts by mass or less, the processability and the workability tend to be improved, and there is a tendency to prevent the lowering of the low temperature characteristics due to the increase of the amount of silica.

  The vulcanized rubber composition according to the present invention may further contain rubber components other than IR and BR, silane coupling agents, fillers such as carbon black, softeners such as oil, waxes, anti-aging agents, if necessary, in addition to the above materials. It is preferable to contain an agent, stearic acid, zinc oxide, a vulcanizing agent, a vulcanization accelerator, and various other materials generally used in the tire industry.

  Other rubber components include styrene butadiene rubber, acrylonitrile butadiene rubber, diene rubber such as chloroprene rubber, ethylene propylene rubber and the like.

  The total content of butadiene rubber and isoprene rubber in all rubber components of the vulcanized rubber composition of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass. preferable. The higher the total content of butadiene rubber and isoprene rubber, the better the low temperature characteristics, and the required on-ice performance can be exhibited, so the correlation between the specified ranges of α, β and γ and the function is It is preferable to use a rubber component consisting only of butadiene rubber and isoprene rubber as the rubber component because it is high.

  The silane coupling agent is not particularly limited, but any silane coupling agent conventionally used in combination with silica can be used in combination in the rubber industry, for example, bis (3-triethoxysilylpropyl) ) Tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide Sulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl Tetrasul , 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthio Sulfides such as carbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilyl propyl methacrylate monosulfide System; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyl trie Mercapto-based compounds such as xysilane; Vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, An amino system such as 3- (2-aminoethyl) aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ Glycidoxy-based such as glycidoxypropylmethyldimethoxysilane; nitro-based such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysila , 2-chloroethyl trimethoxysilane, chloro system such as 2-chloroethyl triethoxy silane; and the like. These silane coupling agents may be used alone or in combination of two or more. Among these, from the viewpoint of good reactivity with silica, sulfides are preferred, and bis (3-triethoxysilylpropyl) disulfide is particularly preferred.

  3 mass parts or more are preferable, and, as for content with respect to 100 mass parts of silicas in the case of containing a silane coupling agent, 6 mass parts or more are more preferable. By setting the content of the silane coupling agent to 3 parts by mass or more, the breaking strength can be improved. Moreover, 12 mass parts or less are preferable, and, as for content with respect to 100 mass parts of silica of this silane coupling agent, 10 mass parts or less are more preferable. By setting the content of the silane coupling agent to 12 parts by mass or less, an effect commensurate with the increase in cost can be obtained.

  The carbon black may, for example, be furnace black, acetylene black, thermal black, channel black or graphite. These carbon blacks may be used alone or in combination of two or more. Among these, furnace black is preferred because it can improve low temperature properties and wear performance in a well-balanced manner.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² / g or more, more preferably 90 m ² / g or more, from the viewpoint of obtaining sufficient reinforcement and abrasion resistance. Also, N ₂ SA of carbon black is excellent in dispersibility, from the viewpoint that it is difficult to heat generation, preferably 300 meters ² / g or less, more preferably 250m ² / g. N ₂ SA can be measured according to JIS K 6217-2 "Carbon black for rubber-Basic characteristics-Part 2: Determination of specific surface area-Nitrogen adsorption method-Single point method".

  1 mass part or more is preferable, and, as for content with respect to 100 mass parts of all the rubber components in the case of containing carbon black, 5 mass parts or more are preferable. By making the content of carbon black 1 part by mass or more, sufficient reinforcing properties tend to be obtained. Moreover, 105 mass parts or less are preferable, as for content of carbon black, 60 mass parts or less are more preferable, and 20 mass parts or less are more preferable. By setting the content of carbon black to 105 parts by mass or less, processability is improved, heat generation can be suppressed, and abrasion resistance can be improved.

  The oil is not particularly limited, and, for example, a process oil, a vegetable oil or a mixture thereof can be used. As the process oil, for example, paraffin-based process oil, aroma-based process oil, naphthene-based process oil and the like can be used. As vegetable oil, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, corn oil, safflower oil, safflower oil, sesame oil, olive oil, Sunflower oil, palm kernel oil, soy sauce, jojoba oil, macadamia nut oil, soy sauce, etc. may be mentioned. Among them, it is preferable to use a process oil, particularly a paraffinic process oil.

  When the oil is contained, the content is preferably 15 parts by mass or more, and more preferably 20 parts by mass or more with respect to 100 parts by mass of the entire rubber component. When the content of oil is 15 parts by mass or more, there is a tendency that the performance on ice necessary for forming a studless tire is exhibited. Moreover, 80 mass parts or less are preferable, and, as for content of oil, 70 mass parts or less are more preferable. By setting the content of oil to 80 parts by mass or less, there is a tendency to prevent deterioration of processability, deterioration of abrasion resistance, and deterioration of aging physical properties.

  As the antiaging agent used in the present invention, each compound of amine type, phenol type and imidazole type, and an antiaging agent such as metal salt of carbamic acid can be appropriately selected and blended, and these antiaging agents And may be used alone or in combination of two or more. Among them, amine-based antioxidants are preferred because ozone resistance can be significantly improved, and the effect is prolonged, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine is more preferred. .

  The content with respect to 100 mass parts of all the rubber components in the case of containing an antiaging agent is 0.5 mass part or more, 1.0 mass part or more is more preferable, 1.2 mass part or more is more preferable. By setting the content of the antiaging agent to 0.5 parts by mass or more, sufficient ozone resistance tends to be obtained. Moreover, 8 mass parts or less are preferable, as for content of anti-aging agent, 4 mass parts or less are more preferable, and 2.5 mass parts or less are more preferable. By setting the content of the antiaging agent to 8 parts by mass or less, it is possible to suppress discoloration and to suppress bleeding.

  As wax, stearic acid and zinc oxide, any of those generally used in the rubber industry can be suitably used.

  The vulcanizing agent is not particularly limited, and those generally used in the rubber industry can be used, but those containing a sulfur atom are preferable, and powdered sulfur is particularly preferably used.

  The vulcanization accelerator is also not particularly limited, and those generally used in the rubber industry can be used.

  The vulcanized rubber composition of the present invention preferably contains 15 to 120 parts by mass of a filler and 15 to 80 parts by mass of a softener with respect to 100 parts by mass of a rubber component containing an isoprene rubber and a butadiene rubber. .

  15 mass parts or more are preferable with respect to 100 mass parts of rubber components, and, as for content of a filler, 30 mass parts or more are more preferable. By setting the content of the filler to 15 parts by mass or more, the abrasion resistance, the fracture characteristics, and the fuel economy tend to be favorable. Moreover, 120 mass parts or less are preferable, and, as for content of a filler, 100 mass parts or less are more preferable. By setting the content of the filler to 120 parts by mass or less, the processability and the workability tend to be improved, and there is a tendency to prevent the lowering of the low temperature characteristics due to the filler increase. The fillers include silica, carbon black, aluminum hydroxide and the like, and it is preferable to blend 50% by mass or more, more preferably 70% by mass or more of silica with respect to the total amount of fillers.

  15 mass parts or more are preferable with respect to 100 mass parts of rubber components, and, as for content of a softener, 20 mass parts or more are more preferable. By setting the content of the softener to 15 parts by mass or more, the on-ice performance required for a studless tire tends to be exhibited. Moreover, 80 mass parts or less are preferable, and, as for content of a softener, 70 mass parts or less are more preferable. By setting the content of the softener to 80 parts by mass or less, there is a tendency to prevent the deterioration of the processability, the decrease of the abrasion resistance, and the decrease of the aging physical properties. Softeners include aromatic oils, naphthenic oils, paraffinic oils, terpene resins, and the like.

  A publicly known method can be used as a manufacturing method of the vulcanized rubber composition of the present invention, for example, it manufactures by the method of kneading the above-mentioned each component with a Banbury mixer, a kneader, an open roll etc., and vulcanizing afterwards. it can.

  Also, the kneading step in producing the vulcanized rubber composition of the present invention is carried out by kneading all rubber components and silica at one time according to the type of rubber used and the like, butadiene rubber An isoprene-based rubber may be added to the kneaded product of silica and kneaded to perform kneading, or a method of performing kneading after preparing a master batch of each rubber component and silica may be appropriately selected.

  The vulcanized rubber composition of the present invention can also be used for tire components such as treads, carcasses, sidewalls, beads, etc., tire applications such as treads, anti-vibration rubbers, belts, hoses, and other industrial products. . Among them, because they are excellent in low fuel consumption and abrasion resistance, they are suitably used in treads, and are further suitable for cap treads when the tread is a two-layer tread structure consisting of a cap tread and a base tread. Used for

  The tire of the present invention can be produced by a conventional method using the vulcanized rubber composition of the present invention. That is, at the unvulcanized stage of the vulcanized rubber composition of the present invention, the rubber composition is extruded according to the shape of the tread of a tire, and is bonded together with other tire members on a tire molding machine. By molding, an unvulcanized tire is formed, and the unvulcanized tire is heated and pressed in a vulcanizer, whereby the tire of the present invention can be manufactured.

  Hereinafter, the present invention will be described based on examples, but the present invention is not limited to the examples.

Examples 1 to 4 and Comparative Examples 1 to 3
The wear resistance performance and the low fuel consumption performance of each vulcanized rubber composition having the values shown in Table 1 for the indicators α, β, γ and δ of the vulcanized rubber composition were evaluated. The test results are shown in Table 1. In addition, the measurement and evaluation of (alpha), (delta), abrasion resistance performance, and low fuel consumption performance stored the vulcanized rubber composition at room temperature, and performed about 200 hours after completion of vulcanization (about 1 week after). β corresponds to the content (mass) of butadiene rubber with respect to the sum of the content (mass) of butadiene rubber and isoprene rubber contained when producing a vulcanized rubber composition, and γ is α / β is there.

<Abrasion resistance performance>
The amount of wear was measured at a slip rate of 20% with a surface rotation speed of 50 m / min, an additional load of 3.0 kg and a falling sand amount of 15 g / min using a Lambourn wear tester manufactured by Iwamoto Manufacturing Co., Ltd. Took the reciprocal of And the inverse number of the abrasion loss of Comparative Example 1 was set to 100, and the inverse number of the other abrasion loss was represented by an index. The larger the index, the better the wear resistance.

<Fuel efficiency performance>
From the sheet-like vulcanized rubber composition, a strip-shaped test piece having a width of 1 mm or 2 mm and a length of 40 mm was punched out and subjected to a test. Using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd., tan δ was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz, and a temperature of 50 ° C., and tan δ of each formulation was expressed as an index according to the following formula. The larger the index, the lower the rolling resistance and the better the fuel economy.
(Fuel efficiency index) = (tan δ of Comparative Example 1) / (tan δ of each composition) × 100

<Evaluation of morphology and evaluation of uneven distribution of silica>
The vulcanized rubber composition was surfaced and observed using a scanning electron microscope (SEM). The morphology of each phase could be confirmed by contrast comparison. As a result, in the vulcanized rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 3, the phase containing butadiene rubber (BR phase) and the phase containing isoprene rubber (IR phase) are incompatible with each other. It was confirmed that there is. The BR phase formed the sea phase, and the IR phase formed the island phase.

  Silica can be observed in particulate form. For 2 SEM images of one sample, 10 regions of 2 μm × 2 μm not overlapping with each other were selected. In each region, the silica area per unit area of each phase was measured, and the silica abundance of BR phase was calculated. It was confirmed that the difference between the maximum value and the minimum value of the 10 values was within 10%, and the average of 10 values was taken as α.

<Evaluation of silica dispersion rate>
An SEM observation image is converted into a binary image of a rubber portion and a silica portion, and an average distance between adjacent silica aggregates is determined using an automatic image processing and analysis system LUZEX (registered trademark) AP manufactured by Nireco Co., Ltd. The standard deviation was calculated to obtain δ.

  From the results of Table 1, in an incompatible system having a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase), the abundance α of silica in BR phase and butadiene rubber It can be seen that the wear resistance performance and the low fuel consumption performance can be improved in a well-balanced manner by setting the vulcanized rubber composition in which the ratio β of β is within the predetermined range.

Hereinafter, various materials used in Production Reference Examples 1 to 4 and Production Comparative Reference Examples 1 to 3 will be collectively shown. The vulcanized rubber compositions obtained by Production Reference Examples 1 to 4 and Production Comparative Examples 1 to 3 correspond to the vulcanized rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 3, respectively.
Butadiene rubber (BR1): BR 730 (unmodified, cis 1,4-content 95%) manufactured by JSR Corporation
Butadiene rubber (BR2): BR 150B (unmodified, cis 1,4-content 98%) manufactured by Ube Industries, Ltd.
Butadiene rubber (BR3): manufactured according to the following synthesis example 1 isoprene rubber (IR): natural rubber (NR) (RSS # 3)
Carbon black: Diablack I (ISAF, N ₂ SA: 114 m ² / g, average particle size: 23 nm) manufactured by Mitsubishi Chemical Corporation
Silica: ULTRASIL (registered trademark) VN3 (N ₂ SA: 175 m ² / g) manufactured by Evonik Degussa
Silane coupling agent: Si266 manufactured by Evonik Degussa
Mineral oil: PS-32 (paraffin-based process oil) manufactured by Idemitsu Kosan Co., Ltd.
Stearic acid: "Mochi" made by NOF Corporation
Zinc oxide: Zinc oxide two-kind anti-aging agent manufactured by Mitsui Mining & Smelting Co., Ltd. Noclack 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylene manufactured by Ouchi Emerging Chemical Industry Co., Ltd. Diamine)
Wax: Ozoace wax sulfur manufactured by Nippon Seikei Co., Ltd. Powder sulfur vulcanization accelerator NS manufactured by Tsurumi Chemical Industry Co., Ltd. NS: Noccellar NS (N-tert-butyl- made by Ouchi Emerging Chemical Industry Co., Ltd.) 2-benzothiazolylsulfenamide)
Vulcanization accelerator DPG: Noxceler D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Co., Ltd.

Synthesis Example 1: Preparation of Modified Conjugated Diene-Based Polymer (1) Synthesis of Conjugated Diene-Based Polymer A cyclohexane solution previously containing 0.18 mmol of neodymium versatate, a toluene containing 3.6 mmol of methylalumoxane Solution, toluene solution containing 6.7 millimoles of diisobutylaluminum hydride, and toluene solution containing 0.36 millimoles of trimethylsilyl iodide and 0.90 millimole of 1,3-butadiene are reacted and aged at 30 ° C. for 60 minutes A catalyst composition (iodine atom / lanthanoid-containing compound (molar ratio) = 2.0) was obtained. Subsequently, 2.4 kg of cyclohexane and 300 g of 1,3-butadiene were charged into a nitrogen-substituted 5 L autoclave. Then, the catalyst composition was charged into the autoclave and subjected to a polymerization reaction at 30 ° C. for 2 hours to obtain a polymer solution. Incidentally, the reaction conversion of the introduced 1,3-butadiene rubber was approximately 100%.

  Here, in order to measure various physical property values of a conjugated diene polymer (hereinafter, also referred to as "polymer"), that is, one before modification, 200 g of a polymer solution is drawn out from the above polymer solution, and this polymer A methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol is added to the solution to terminate the polymerization reaction, and then the solvent is removed by steam stripping and drying on a roll at 110 ° C. The resulting dried product was used as a polymer.

The polymer was measured for various physical properties by the measurement methods shown below. As a result, the Mooney viscosity (ML _{1 + 4} (100 ° C.)) is 12 and the molecular weight distribution (Mw / Mn) is 1.6. The amount of -1,4-bond was 99.2% by mass, and the amount of 1,2-vinyl bond was 0.21% by mass.

[Mooney viscosity (ML _{1 + 4} (100 ° C.))]
According to JIS K 6300, using an L rotor, measurement was performed under the conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 100 ° C.

[Molecular weight distribution (Mw / Mn)]
Using a gel permeation chromatograph (trade name: HLC-8120GPC, manufactured by Tosoh Corporation), measurement was made under the following conditions using a differential refractometer as a detector, and calculated as a standard polystyrene conversion value.
Column; trade name "GMHHXL", (made by Tosoh Corporation) two,
Column temperature: 40 ° C.,
Mobile phase: tetrahydrofuran,
Flow rate: 1.0 ml / min,
Sample concentration: 10 mg / 20 ml

[Cis-1,4-bond amount, 1,2-vinyl bond amount]
The content of cis-1,4-bond and the content of 1,2-vinyl bond were determined by ¹ H-NMR analysis and ¹³ C-NMR analysis. For NMR analysis, a trade name "EX-270" manufactured by JEOL Ltd. was used. Specifically, as ¹ H-NMR analysis, it is a polymer from the signal intensities at 5.30 to 5.50 ppm (1,4-bond) and 4.80 to 5.01 ppm (1,2-bond). The ratio of 1,4-bond to 1,2-bond was calculated. Furthermore, as the ¹³ C-NMR analysis, from the signal intensities at 27.5 ppm (cis-1,4-bond) and 32.8 ppm (trans-1,4-bond), cis-1,4 in the polymer -The ratio of bond to trans-1,4-bond was calculated. The ratio of these calculated values was calculated, and it was set as the amount of cis-1,4-bonds (mass%) and the amount of 1,2-vinyl bonds (mass%).

(2) Synthesis of Modified Conjugated Diene-Based Polymer In order to obtain a modified conjugated diene-based polymer (hereinafter, also referred to as “modified polymer”), a polymer solution of the conjugated diene-based polymer of Synthesis Example 1 is prepared as follows: I did the processing. A toluene solution containing 1.71 millimoles of 3-glycidoxypropyltrimethoxysilane was added to the polymer solution maintained at a temperature of 30 ° C., and reaction was performed for 30 minutes to obtain a reaction solution. Then, a toluene solution containing 1.71 mmol of 3-aminopropyltriethoxysilane was added to the reaction solution and stirred for 30 minutes. Subsequently, a toluene solution containing 1.28 mmol of tetraisopropyl titanate was added to the reaction solution and stirred for 30 minutes. Thereafter, in order to stop the polymerization reaction, a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added to make this solution a modified polymer solution. The yield was 2.5 kg. Subsequently, 20 L of an aqueous solution adjusted to pH 10 with sodium hydroxide was added to this modified polymer solution, and a condensation reaction was carried out at 110 ° C. for 2 hours with a solvent removal. Then, it dried with a 110 degreeC roll, and made the obtained dried product the modified polymer.

With respect to the modified polymer, various physical property values were measured by the measurement methods shown below (however, measurement of the molecular weight distribution (Mw / Mn) was performed under the same conditions as the above-mentioned polymer), Mooney viscosity (ML _{1 + 4} (125 ° C.) is 46, molecular weight distribution (Mw / Mn) is 2.4, cold flow value is 0.3 mg / min, stability over time is 2, glass transition temperature Was -106 ° C.

[Mooney viscosity (ML _{1 + 4} (125 ° C.))]
According to JIS K 6300, using an L rotor, measurement was performed under the conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 125 ° C.

[Cold flow value]
The measurement was made by extruding the polymer through a 1/4 inch orifice at a pressure of 3.5 lb / in ² and a temperature of 50 ° C. After standing for 10 minutes in order to achieve a steady state, the extrusion rate was measured, and the measured value was expressed in milligrams per minute (mg / min).

[Temporal stability]
The Mooney viscosity (ML _{1 + 4} (125 ° C.)) after storage in a thermostat at 90 ° C. for 2 days is a value calculated by the following equation. The smaller the value, the better the temporal stability.
Formula: [Mooney viscosity (ML _{1 + 4} (125 ° C.)) after storage for 2 days in a thermostat of 90 ° C.]-[Mooney viscosity (ML _{1 + 4} (125 ° C.)) measured immediately after synthesis]

[Glass-transition temperature]
The glass transition temperature is measured according to JIS K 7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Co., Ltd., while raising the temperature at a temperature rising rate of 10 ° C./min. , As the glass transition start temperature.

Production Reference Examples 1 to 3 and Comparative Production Reference Examples 1 to 3
According to the formulation shown in step (I) of Table 2, a rubber component, silica and other materials are added, and a kneaded product is obtained by kneading for 3 minutes at a discharge temperature of 150 ° C. using a 1.7 L Banbury mixer. The Next, according to the composition shown in step (II) of Table 2, the obtained kneaded product and other materials were added, and the mixture was kneaded for 2 minutes at a discharge temperature of 150 ° C. to obtain a kneaded product. Sulfur and a vulcanization accelerator are added to the obtained kneaded product according to the compounding recipe of step (III) in Table 2 and kneaded for 5 minutes at 150 ° C. using an open roll to obtain an unvulcanized rubber composition The In addition, about manufacture reference example 1, the kneaded material of the compounding prescription described in each row of Table 2 at the process (I) was obtained, respectively, and those both kneaded materials were used for process (II).

  Each obtained unvulcanized rubber composition was press vulcanized with a 0.5 mm-thick mold at 170 ° C. for 12 minutes to obtain a vulcanized rubber composition.

1 BR phase 2 IR phase 3 silica 4 carbon black

Claims (5)

A vulcanized rubber composition comprising a rubber component consisting of butadiene rubber and isoprene rubber only,
It has a phase containing butadiene rubber and silica (BR phase) and a phase containing isoprene rubber and silica (IR phase),
BR phase and IR phase are mutually incompatible,
The abundance ratio α of silica in the BR phase after vulcanization satisfies formula 1 below
The proportion β of butadiene rubber satisfies the following formula 2,
Abundance of silica to the ratio of butadiene rubber beta gamma satisfies the following formula 3, and dispersion of the whole of the silica δ is less than the formula 4,
Vulcanized rubber composition wherein the butadiene rubber is a butadiene rubber having a cis 1, 4 bond content of 90% or more and the isoprene rubber is a natural rubber (however, the weight average molecular weight is 1.0 × 10 ^{3 to} 2.0) Except when containing × 10 ⁵ epoxidized butadiene-based polymer).
0.3 ≦ α ≦ 0.7 (Equation 1)
0.4 ≦ β ≦ 0.8 (Equation 2)
0.6 ≦ γ ≦ 1.4 (Equation 3)
δ ≦ 0.8 (Equation 4)
(Here, α = amount of silica in BR phase / (amount of silica in BR phase + amount of silica in IR phase), β = mass of butadiene rubber in vulcanized rubber composition / (vulcanized rubber composition Mass of butadiene rubber + mass of isoprene rubber in the vulcanized rubber composition), γ = α / β, and δ = standard distance between silicas / average distance between silicas) Against rubber component 100 parts by weight of silica containing 5 to 150 parts by claim 1 vulcanized rubber composition. Against rubber to 100 parts by weight of the component, a filler containing 15 to 120 parts by weight, the filler is a vulcanized rubber composition of claim 1 or 2, wherein containing 50 mass% or more of the silica relative to the total amount of filler object. Rubber respect to 100 parts by weight of the component, vulcanized rubber composition according to any one of claims 1 to 3 containing 15 to 80 parts by weight of a softening agent. A tire having a tread made of the vulcanized rubber composition according to any one of claims 1 to 4 .