JP6042399B2 - Rubber composition and pneumatic tire - Google Patents

Description

The present invention relates to a rubber composition and a pneumatic tire using the same.

Carbon black has a great influence on the performance of the rubber composition when blended in the rubber composition due to physical properties such as specific surface area, structure and surface properties. For this reason, carbon black having different characteristics is selectively used depending on the required performance of the rubber composition, the environmental conditions in which the rubber composition is used, and the like (for example, Patent Document 1).

The tread rubber that is in contact with the ground is required to have excellent resistance to wear during running (wear resistance), low hysteresis loss that occurs when the rubber is running, and low heat build-up. In order to achieve both wear resistance and low heat build-up, methods such as a high filling method of carbon black, a high specific surface area (small particle size), or a method using carbon black having a high structure are being studied. However, when these carbon blacks are used, although the wear resistance is improved, the low heat build-up may not be sufficient.

In addition, as a technique for improving the wear resistance of a tire with characteristics other than the specific surface area and structure of carbon black, a technique for increasing the sharpness of the aggregate diameter distribution of carbon black has been proposed. However, the rubber composition in which the carbon black is blended has reduced heat build-up, and the low heat build-up of a tire using the rubber composition as a tread may not be sufficient. Further, if the sharpness of the aggregate diameter distribution is lowered (increases the broadness), the low heat buildup of the tire can be improved, but at the same time, the wear resistance tends to be lowered. Thus, the method of adjusting only the aggregate diameter distribution of carbon black is not an effective means for achieving both wear resistance and low heat build-up of the tire.

In this way, wear resistance and low heat build-up are in a trade-off relationship, and developments are underway to achieve both performances at a high level, but carbon black that exhibits sufficient characteristics has not yet been found. The current situation is not.

JP 2001-081239 A

An object of the present invention is to solve the above-mentioned problems and to provide a rubber composition capable of achieving both wear resistance and low heat build-up, and a pneumatic tire using the same.

As a result of intensive studies, the present inventors have determined that a rubber component, carbon black having a specific aggregate characteristic such as carbon black obtained by using a specific raw material oil, and a specific amount of specific silica are rubber. The compounding of the composition has found that both wear resistance and low heat build-up can be achieved, and the present invention has been completed.

The present invention relates to a rubber composition comprising a rubber component, one or more carbon blacks, and silica, wherein at least one of the carbon blacks has an average boiling point T as a raw material oil for producing the carbon black. (° C) and specific gravity D (60/60 ° F) when compared with 60 ° F water, the BMCI value calculated by the following formula is 150 or less, and the aliphatic hydrocarbon ratio is 30 mass% or more. It is carbon black obtained by using raw material oil, the nitrogen adsorption specific surface area of the silica is 40 to 400 m ² / g, and the silica content with respect to 100 parts by mass of the rubber component in the rubber composition It is related with the rubber composition whose quantity is 1-120 mass parts.
BMCI = 48640 / (T + 273) + 473.7D-456.8

Carbon obtained by using at least one of the carbon blacks as a raw material oil for producing the carbon black, a raw material oil having a BMCI value of 95 or more and an aliphatic hydrocarbon ratio of 60% by mass or less Black is preferred.

In 100% by mass of aliphatic hydrocarbons contained in the raw material oil, 10% by mass or more is preferably an aliphatic hydrocarbon derived from animal or vegetable oils or modified products thereof.

The raw material oil preferably contains tall oil.

The carbon black is preferably carbon black produced by a furnace method.

The present invention also provides a rubber composition comprising a rubber component, one or more carbon blacks, and silica, wherein at least one of the carbon blacks has a maximum frequency diameter of a distribution curve of a Stokes equivalent diameter as an aggregate characteristic. Carbon black having (Dmod) of 79 nm or less and a ratio of half width (ΔD50) of distribution curve to Dmod (ΔD50 / Dmod) of 0.78 or more, and the nitrogen adsorption specific surface area of the silica is 40 to 400 m ² / It is g, It is related with the rubber composition whose content of the said silica is 1-120 mass parts with respect to 100 mass parts of said rubber components in the said rubber composition.

The present invention also relates to a vulcanized rubber composition obtained by vulcanizing the rubber composition, wherein the tan δ peak temperature is −16 ° C. or higher.

The rubber composition is preferably used as a tire rubber composition.

The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, since it is a rubber composition containing a rubber component, a specific carbon black, and a specific amount of specific silica, it is possible to achieve both wear resistance and low heat build-up, and a pneumatic that is excellent in both performances. Tires can be provided.

The first aspect of the present invention is a rubber composition comprising a rubber component, one or more carbon blacks, and silica, wherein at least one of the carbon blacks is used as a raw material oil for producing the carbon black, The average boiling point T (° C) and specific gravity D (60/60 ° F) when compared with water at 60 ° F is calculated using the following formula to have a BMCI value of 150 or less and an aliphatic hydrocarbon ratio of 30% by mass Carbon black (1) obtained by using the raw material oil as described above, wherein the silica has a nitrogen adsorption specific surface area of 40 to 400 m ² / g, and the rubber composition contains 100 parts by mass of the rubber component. On the other hand, it is related with the rubber composition whose content of the said silica is 1-120 mass parts.
BMCI = 48640 / (T + 273) + 473.7D-456.8

According to a second aspect of the present invention, there is provided a rubber composition comprising a rubber component, one or more carbon blacks, and silica, wherein at least one of the carbon blacks has a maximum Stokes equivalent diameter distribution curve as an aggregate characteristic. Carbon black (1) having a frequency diameter (Dmod) of 79 nm or less and a ratio of half width (ΔD50) of distribution curve to Dmod (ΔD50 / Dmod) of 0.78 or more, and the nitrogen adsorption specific surface area of the silica is It is 40-400 m < ² > / g, It is related with the rubber composition whose content of the said silica is 1-120 mass parts with respect to 100 mass parts of said rubber components in the said rubber composition.

In the present invention, Dmod is a raw material oil for producing carbon black, such as carbon black (1) obtained by using a raw material oil having a BMCI value of a specific value or less and an aliphatic hydrocarbon ratio of a specific value or more. While maintaining or improving good low heat build-up by blending a rubber composition with carbon black having a specific aggregate characteristic of ΔD50 / Dmod equal to or higher than a specific value, ΔD50 / Dmod, and a specific value. The wear resistance can be improved, and the wear resistance and the low heat build-up can be achieved at the same time.

Examples of the rubber component according to the present invention include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and styrene isoprene butadiene rubber (SIBR), modified rubbers thereof, and ethylene-propylene copolymer. Examples thereof include a polymer and an ethylene-octene copolymer.

As the modified rubber, at least one terminal is modified with a modifier having a functional group that interacts with silica (preferably a functional group containing at least one atom from nitrogen, oxygen, and silicon). Examples include modified isoprene rubber, modified BR, and modified SBR. Those having such a functional group at both ends and in the main chain may be used.
Examples of the functional group include amino group, amide group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, carboxyl group, hydroxyl group, nitrile group, and pyridyl group. .

A rubber component may be used independently and may use 2 or more types together. Especially, it is preferable to use BR and SBR as a rubber component together with carbon black (1) and a specific amount of specific silica because the effect of the present invention can be obtained better, and BR and SBR are used in combination. It is more preferable.

Examples of the isoprene-based rubber include isoprene rubber (IR), natural rubber (NR), and epoxidized natural rubber (ENR). As the NR, for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20 can be used. The IR is not particularly limited, and those commonly used in the tire industry can be used.

It is not particularly limited as BR, for example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd. BR containing syndiotactic polybutadiene crystals can be used. Among these, from the reason that the wear resistance is good, the cis content of BR is preferably 90% by mass or more, and more preferably 95% by mass or more. In the present specification, the cis content is a value calculated by infrared absorption spectrum analysis.

When the rubber composition according to the present invention contains BR, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. is there. If it is less than 5% by mass, sufficient wear resistance may not be ensured. The content is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. If it exceeds 50% by mass, sufficient processability may not be obtained.

The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) and the like can be used. Among these, S-SBR is preferable because the effects of the present invention can be obtained more suitably and the wet grip performance is improved.

The vinyl content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more, and further preferably 30% by mass or more. There exists a possibility that the effect of this invention may not be acquired suitably as this vinyl content rate is less than 20 mass%. The vinyl content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 70% by mass or less. When the vinyl content exceeds 90% by mass, the wear resistance tends to deteriorate. The vinyl content of SBR can be measured by infrared absorption spectrum analysis.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more. When the styrene content is less than 5% by mass, the effects of the present invention tend not to be obtained suitably. Moreover, this styrene content rate becomes like this. Preferably it is 60 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 45 mass% or less. When the styrene content exceeds 60% by mass, the low exothermic property tends to decrease. In the present invention, the styrene content of SBR is calculated by ¹ H-NMR measurement.

When the rubber composition according to the present invention contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. is there. If it is less than 50% by mass, sufficient wet grip performance may not be ensured. Moreover, this content becomes like this. Preferably it is 95 mass% or less, More preferably, it is 90 mass% or less, More preferably, it is 85 mass% or less. If it exceeds 95% by mass, sufficient wear resistance may not be obtained.

In the present invention, the carbon black (1) is used. By blending the carbon black (1) together with a specific amount of specific silica, both wear resistance and low heat build-up can be achieved.

In the second aspect of the present invention, the maximum frequency diameter (Dmod) of the distribution curve of the Stokes equivalent diameter as the aggregate characteristic of the carbon black (1) is 79 nm or less, preferably 69 nm or less, more preferably 63 nm or less. If it exceeds 79 nm, the effect of the present invention (particularly, the effect of improving wear resistance) cannot be obtained sufficiently. Although the minimum of this Dmod is not specifically limited, Preferably it is 50 nm or more, More preferably, it is 56 nm or more. If it is less than 50 nm, the dispersibility is inferior, and the fracture characteristics and wear resistance tend to decrease.

In the second aspect of the present invention, the ratio (ΔD50 / Dmod) of the half width (ΔD50) of the distribution curve to Dmod as the aggregate characteristic of carbon black (1) is 0.78 or more, preferably 0.90. As mentioned above, More preferably, it is 1.0 or more, More preferably, it is 1.1 or more. If it is less than 0.78, the effect of the present invention (particularly, the effect of improving low heat build-up) cannot be obtained sufficiently. The upper limit of ΔD50 / Dmod is not particularly limited, but is preferably 2.5 or less, more preferably 2.0 or less. If it exceeds 2.5, the wear resistance is deteriorated and the desired effect may not be obtained.

In this specification, Dmod and ΔD50 of carbon black are values measured by the following method.
A carbon black sample precisely weighed in a 20% aqueous ethanol solution to which a surfactant (“NONIDET P-40” manufactured by SIGMA CHEMICAL) is added is added to prepare a sample solution having a carbon black concentration of 0.01% by weight. A carbon black slurry is prepared by dispersing the sample solution for 5 minutes using an ultrasonic disperser (“Ultrasonic Generator USV-500V” manufactured by Ultrasonic Industry Co., Ltd.) with a vibration frequency of 200 kHz and an output of 100 W. On the other hand, 10 ml of a spin solution (pure water) was injected into a centrifugal sedimentation type particle size distribution measuring apparatus (“BI-DCP PARTIC LSIZ” manufactured by BROOK HAVEN INSTRUMENTS), and 1 ml of a buffer solution (20 vol% ethanol aqueous solution) was further injected. Thereafter, 1 ml each of the carbon black slurry prepared above is injected, and the Stokes equivalent diameter is measured by centrifugal sedimentation at a rotation speed of 8000 rpm, and a histogram of the occurrence frequency relative to the Stokes equivalent diameter is prepared. Let C be the intersection of a straight line passing through the peak (A) of the histogram and parallel to the Y axis and the X axis of the histogram. The Stokes diameter at C is the maximum frequency Stokes equivalent diameter (Dmod). Further, an intermediate point (D, E) between a straight line G passing through F and parallel to the X axis and a histogram distribution curve (D, E) is obtained with the midpoint of the line segment AC as F, and the difference between the D and E Stokes diameters The absolute value is defined as the Stokes equivalent diameter half-width value (half-value width of distribution curve (ΔD50)).

The carbon black (1) has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of preferably 60 to 150 m ² / g, more preferably 80 to 145 m ² / g, still more preferably 100 to 140 m ² / g, and particularly preferably. Is 105 to 135 m ² / g. The effect of this invention is acquired more suitably as CTAB is in the said range.
In the present specification, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of carbon black is a value measured in accordance with JIS K6217-3: 2001.

The iodine adsorption amount (IA) (mg / g) of carbon black (1) is preferably 100 to 400 mg / g, more preferably 110 to 300 mg / g, and still more preferably 120 to 250 mg / g. When the iodine adsorption amount (IA) is within the above range, the effect of improving the wear resistance is more suitably obtained, and the effect of the present invention is more suitably obtained.
In the present specification, the iodine adsorption amount (IA) of carbon black is a value measured according to JIS K6217-1: 2008.

The ratio (CTAB / IA) of the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) to the iodine adsorption amount (IA) (mg / g) of the carbon black (1) is preferably 0.8 to 1.2 m ² / mg. More preferably, it is 0.85-1.15 m < ² > / mg, More preferably, it is 0.9-1.1 m < ² > / mg. When CTAB / IA is within the above range, the effect of the present invention can be more suitably obtained.

The surface activity index represented by CTAB / IA can be considered as an index of the crystallinity (graphitization rate) of carbon black. That is, as CTAB / IA is higher, crystallization is less advanced, and the interaction between carbon black and the rubber component tends to increase.
CTAB / IA is also positioned as a parameter for evaluating the amount of acidic functional groups present on the carbon black surface. The acidic functional group on the surface of carbon black contributes to the interaction with the rubber component, but the higher the CTAB / IA, the more acidic functional groups are present on the surface of the carbon black. Therefore, when CTAB / IA is within the above range, a more remarkable reinforcing effect can be exerted on the rubber component, and the effect of the present invention can be obtained more suitably.

24M4 dibutyl phthalate oil absorption of carbon black (1) (24M4DBP) is preferably 50~120cm ³ / 100g, more preferably 70~120cm ³ / 100g, more preferably 90~115cm ³ / 100g, particularly preferably 95 to 110cm is a ³ / 100g. When 24M4DBP is within the above range, the effect of the present invention can be more suitably obtained.
In the present specification, the 24M4 dibutyl phthalate oil absorption (24M4DBP) of carbon black is a value measured according to ASTM D3493-85a.

Carbon black (1) may be acidic, neutral or basic, but preferably has a pH of 2.0 to 10.0 as measured according to JIS K6220-1. More preferably, it is 9.5. When the pH of the carbon black (1) is within the above range, the mechanical strength and wear resistance of the rubber composition can be improved more suitably, and the effects of the present invention can be obtained more suitably.

As a method for producing carbon black (1), for example, a method characterized in that a raw material oil having a BMCI value of 150 or less and an aliphatic hydrocarbon ratio of 30% by mass or more is used as a raw material oil (raw material hydrocarbon). Is preferably adopted. Thereby, carbon black (1) which has the said characteristic is obtained suitably. Further, according to this method, carbon black is prepared in one pot, that is, using the above-mentioned raw material oil, without mixing a plurality of prepared carbon blacks or performing post-treatment such as surface treatment on the prepared carbon black. The carbon black (1) having the above characteristics can be easily prepared simply by preparing the above.

Here, in this specification, the BMCI value is a value calculated from the average boiling point T (° C.) and specific gravity D (60/60 ° F.) when compared with water at 60 ° F. is there.
The average boiling point T is the temperature at which 50% of the raw material oil is distilled off on a mass basis.
BMCI = 48640 / (T + 273) + 473.7D-456.8

In the first aspect of the present invention, the BMCI value of the feedstock is 150 or less, preferably 140 or less, more preferably 130 or less, still more preferably 120 or less, and particularly preferably 110 or less. If it exceeds 150, the particle size distribution of the carbon black becomes too sharp, the above-mentioned specific aggregate characteristics cannot be obtained, and the low heat build-up is deteriorated. The lower limit of the BMCI value of the feedstock is not particularly limited, but is preferably 95 or more. If it is less than 95, the yield may be deteriorated (a sufficient amount of carbon black cannot be obtained).

In the first aspect of the present invention, the aliphatic hydrocarbon ratio (the content of aliphatic hydrocarbons in 100% by mass of the feed oil) is 30% by mass or more, and preferably 40% by mass or more. If it is less than 30% by mass, the above-mentioned specific aggregate characteristics cannot be obtained, and the low heat build-up property is deteriorated. The upper limit of the aliphatic hydrocarbon ratio is not particularly limited, but is preferably 60% by mass or less. If it exceeds 60% by mass, the yield may be deteriorated (a sufficient amount of carbon black cannot be obtained).

The content of aliphatic hydrocarbons derived from animal and vegetable oils or modified products thereof in 100% by mass of aliphatic hydrocarbons contained in the feedstock oil is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably. 30% by mass or more. The upper limit of this content is not specifically limited, 100 mass% may be sufficient. When the content is within the above range, not only the effect of the present invention can be obtained more suitably, but also the above effect can be achieved using a non-depleted resource as a raw material, so that resource depletion and the environment can be considered.

As the feedstock satisfying the above characteristics, one satisfying the above characteristics may be used alone, or a mixture of two or more kinds so as to satisfy the above characteristics may be used.

Specific examples of raw material oils include: (1) aromatic hydrocarbons such as anthracene; coal-based hydrocarbons such as creosote oil; EHE oil (replicated oil during ethylene production), FCC oil (fluid catalytic cracking residue oil) And a raw material mixture of at least one selected from the group consisting of petroleum heavy oils such as ()) and (2) aliphatic hydrocarbons. These may be modified. Among these, a mixed raw material oil of coal-based hydrocarbon and aliphatic hydrocarbon is preferable.

As the aliphatic hydrocarbon, for example, petroleum-based aliphatic hydrocarbons typified by process oil, and animal and vegetable oils typified by fatty acids such as soybean oil, rapeseed oil, and palm oil can be used.
Here, animal and vegetable oils include fish oil (liver oil) obtained from fish liver, marine animal oil such as sea animal oil obtained from whales, and land animal oil such as beef tallow and pork fat, as well as plant seeds, fruits, and nuclei. It contains fats and oils and the like containing fatty acid glycerides collected from the above.

Among these, as the raw material oil, a mixed raw material oil of coal-based hydrocarbon and petroleum-based aliphatic hydrocarbon, a mixed raw material oil of coal-based hydrocarbon and animal and vegetable oil is preferable, creosote oil and petroleum-based aliphatic hydrocarbon And mixed raw material oil of creosote oil and soybean oil are more preferable. In addition, tall oil containing aliphatic hydrocarbons can also be suitably used as a raw material oil. In addition, as said coal-type hydrocarbon, coal-type aromatic hydrocarbon is preferable.

Carbon black (1) can be produced by a known production method except that the above-mentioned raw material oil is used, and its production method is not particularly limited. Specifically, carbon black (1) is carbonized by spraying raw material oil into combustion gas. A method for producing black is preferably employed, and conventionally known methods such as a furnace method and a channel method are used. Among these, the furnace method shown below is preferable because the above-mentioned specific aggregate characteristics can be suitably obtained.

The furnace method (oil furnace method) is, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-43598 and Japanese Patent Application Laid-Open No. 2004-277443. A process using a device having a reaction zone for introducing hydrocarbons and converting raw material hydrocarbons to carbon black by a pyrolysis reaction, and a reaction stop zone for quenching reaction gas to stop the reaction, combustion conditions, high temperature Carbon blacks having various characteristics can be produced by controlling various conditions such as the combustion gas flow rate, the conditions for introducing the raw material oil into the reaction furnace, and the time from the conversion of carbon black to the termination of the reaction.

In the combustion zone, air, oxygen or a mixture thereof and a gaseous or liquid fuel hydrocarbon are mixed and burned as an oxygen-containing gas to form a high-temperature combustion gas. As the fuel hydrocarbon, petroleum-based liquid fuel such as carbon monoxide, natural gas, coal gas, petroleum gas, heavy oil, and coal-based liquid fuel such as creosote oil are used. The combustion is preferably controlled so that the combustion temperature is in the range of 1400 ° C to 2000 ° C.

In the reaction zone, the raw material hydrocarbon is sprayed and introduced into the high-temperature combustion gas flow obtained in the combustion zone in a co-current flow or in a lateral direction, and the raw material hydrocarbon is thermally decomposed and converted to carbon black. Preferably, the feedstock oil is introduced by one or more burners into a high temperature combustion gas stream having a gas flow rate in the range of 100 to 1000 m / s. The feedstock oil is preferably divided and introduced by two or more burners. In order to improve the reaction efficiency, it is preferable to provide a throttle part in the reaction zone. The ratio of the diameter of the throttle part / the diameter of the upstream area of the throttle part is preferably 0.1 to 0.8.

In the reaction stop zone, water spray or the like is performed to cool the high temperature reaction gas to 1000 to 800 ° C. or less. The time from the introduction of the feedstock to the reaction stop is preferably 2 to 100 milliseconds. The cooled carbon black can be separated and recovered from the gas and then subjected to a known process such as granulation and drying.

The compounding amount of the carbon black (1) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass or more. If it is less than 1 part by mass, the effects of the present invention tend not to be sufficiently obtained. The amount of carbon black is preferably 250 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less, particularly preferably 70 parts by mass or less, and most preferably 40 parts by mass or less. When the amount exceeds 250 parts by mass, the rubber composition becomes too hard, and on the contrary, the wear resistance is lowered, and the processability of the rubber composition tends to be extremely lowered. Also, low exothermicity tends to deteriorate.

In the present invention, carbon black other than carbon black (1) (hereinafter also referred to as carbon black (2)) may be blended with carbon black (1).

Carbon black (2) is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF.

When the rubber composition of the present invention is used for a rubber composition for a tread, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black (2) is preferably 80 m ² / g or more, more preferably 90 m ² / g or more. More preferably, it is 100 m ² / g or more. If it is less than 80 m < ² > / g, there exists a tendency for reinforcement property to fall and sufficient abrasion resistance not to be obtained. Also, _N 2 SA of the carbon black (2) is preferably 200 meters ² / g or less, more preferably 190 m ² / g or less, still more preferably not more than 180 m ² / g. If it exceeds 200 m ² / g, the low heat build-up tends to deteriorate. In addition, the dispersibility is inferior, and the fracture performance and wear resistance tend to decrease.
In this specification, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

When the rubber composition of the present invention is used for a tread rubber composition, the carbon black (2) has a dibutyl phthalate oil absorption (DBP) of preferably 40 ml / 100 g or more, more preferably 60 ml / 100 g or more. If it is less than 40 ml / 100 g, the reinforcing property is lowered, and there is a tendency that sufficient abrasion resistance cannot be obtained. Further, the DBP of carbon black (2) is preferably 300 ml / 100 g or less, more preferably 200 ml / 100 g or less, still more preferably 100 ml / 100 g or less. If it exceeds 300 ml / 100 g, the durability and elongation at break may be deteriorated.
In the present specification, the DBP of carbon black is measured according to JIS K6217-4: 2001.

The total content of carbon black is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, sufficient reinforcement may not be obtained. Further, the total content of the carbon black is preferably 250 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 150 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 50 parts by mass or less. is there. When it exceeds 250 parts by mass, the workability is lowered, and there is a possibility that low heat build-up, wear resistance, and durability are lowered.

The content of carbon black (1) in 100% by mass of carbon black is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 20% by mass or more. If it is less than 1% by mass, sufficient effects of the present invention cannot be obtained, and it may be difficult to achieve both wear resistance and low heat build-up. The content may be 100% by mass, but is preferably 80% by mass or less when used with other carbon black.

In the present invention, silica is used. By blending silica together with carbon black (1), it is possible to synergistically improve the wear resistance and the performance balance of wear resistance and low heat build-up. The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silica), wet process silica (hydrous silica), and wet process silica is preferable because of its large number of silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is 40 m ² / g or more, preferably 55 m ² / g or more, more preferably 60 m ² / g or more, and still more preferably 100 m ² / g or more. There exists a possibility that abrasion resistance may deteriorate that it is less than 40 m < ² > / g. The _N 2 SA of the silica, 400 meters ² / g or less, preferably 300 meters ² / g or less, more preferably 270 meters ² / g or less, still more preferably not more than 200m ² / g. If it exceeds 400 m ² / g, it is difficult to disperse silica and the rolling resistance may be deteriorated.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica is 1 part by mass or more, preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, the effect of blending silica cannot be sufficiently obtained, and the wear resistance tends to decrease. The content of the silica is 120 parts by mass or less, preferably 100 parts by mass or less, more preferably 90 parts by mass or less. If the amount exceeds 120 parts by mass, silica is difficult to disperse, and thus low heat build-up, workability, and wear resistance tend to deteriorate.

In the present invention, fillers other than silica and carbon black may be used. Examples of fillers other than silica and carbon black include mica such as calcium carbonate and sericite, and white fillers such as aluminum hydroxide, magnesium oxide, magnesium hydroxide, clay, talc, alumina, and titanium oxide. . These may be used alone or in combination of two or more.

The total content of all fillers including silica and carbon black (preferably, the total content of silica and carbon black) is preferably 5 parts by mass or more, more preferably 15 parts by mass with respect to 100 parts by mass of the rubber component. As mentioned above, More preferably, it is 20 mass parts or more. The total content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 120 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 80 parts by mass or less. Within the above range, the effects of the present invention can be obtained better.

The total content of carbon black in 100% by mass of the total filler including silica and carbon black is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more. The total content is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less. Within the above range, the effects of the present invention can be obtained better.

The content of silica in 100% by mass of the total filler including silica and carbon black is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more. When the amount is less than 40% by mass, the wet grip performance tends to deteriorate when carbon black is used as the remaining filler. Further, if a filler other than carbon black is used, the wear resistance may be deteriorated. The content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 75% by mass or less.

In the present invention, it is preferable to use a silane coupling agent in combination with silica. As the silane coupling agent, conventionally known silane coupling agents can be used, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxy). Silylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) ) Disulfide, bis (3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-trie Sulfide systems such as xylsilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2- Mercapto series such as mercaptoethyltrimethoxysilane and 2-mercaptoethyltriethoxysilane, vinyl series such as vinyltriethoxysilane and vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane and other amino-based, γ-glycidoxypropyltrie Glycidoxy systems such as toxisilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-nitropropyltrimethoxysilane, 3-nitropropyltri Examples thereof include nitro series such as ethoxysilane, and chloro series such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. In addition, said silane coupling agent may be used independently and may be used in combination of 2 or more type. Of these, sulfide-based silane coupling agents are preferable and bis (3-triethoxysilylpropyl) tetrasulfide is more preferable from the viewpoint of the reinforcing effect of the silane coupling agent, processability, and cost.

3 mass parts or more are preferable with respect to 100 mass parts of silica, and, as for content of a silane coupling agent, 5 mass parts or more are more preferable. If the amount is less than 3 parts by mass, the coupling effect is insufficient and high silica dispersion tends to be not obtained. For this reason, there is a risk that the fuel efficiency and the breaking strength may be reduced. Moreover, 15 mass parts or less are preferable, and, as for content of this silane coupling agent, 10 mass parts or less are more preferable. When it exceeds 15 parts by mass, an excess silane coupling agent remains, which may cause deterioration in processability and fracture characteristics of the resulting rubber composition.

The rubber composition of the present invention preferably contains oil. By blending oil with carbon black (1) and a specific amount of specific silica, the effects of the present invention can be obtained better.
As the oil, for example, process oil, vegetable oil or fat, or a mixture thereof may be used. Examples of the process oil include paraffinic process oil, naphthenic process oil, aromatic process oil (aromatic process oil), and the like. Vegetable oils include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, cocoon oil, jojoba oil, macadamia nut oil, safflower oil, and tung oil. Of these, aromatic process oils are preferred because they are compatible with rubber and can maintain tan δ.

When the rubber composition contains oil, the content of oil is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. . If it is less than 5 parts by mass, the effect of softening rubber (softening effect) is small, and the effect of reducing E ^* may be small. The oil content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. If it exceeds 50 parts by mass, a sufficient softening action can be obtained, but the reinforceability may be significantly reduced, and the wear resistance and durability (destructive properties) may be reduced. The oil content includes the amount of oil contained in rubber (oil-extended rubber).

In addition to the above components, the rubber composition of the present invention includes compounding agents generally used in the production of rubber compositions, for example, vulcanizing agents such as sulfur; vulcanization accelerators; additives such as zinc oxide and stearic acid. Sulfur activators; organic peroxides; processing aids such as extender oils and lubricants; anti-aging agents and the like can be appropriately blended.

Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethylthiuram Thiuram vulcanization accelerators such as disulfide; N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N -Sulfenamide vulcanization accelerators such as oxyethylene-2-benzothiazole sulfenamide, N, N'-diisopropyl-2-benzothiazole sulfenamide; diphenylguanidine, diortolylguanidine, orthotolylbiguanidine, etc. No Niidine vulcanization accelerators can be mentioned, and among them, sulfenamide vulcanization accelerators and / or guanidine vulcanization accelerators are preferred because the effects of the present invention can be obtained better. -T-Butyl-2-benzothiazole sulfenamide and / or diphenylguanidine are more preferred. 0.1-5 mass parts is preferable with respect to 100 mass parts of rubber components, and, as for the usage-amount of a vulcanization accelerator, More preferably, it is 0.2-4 mass parts.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing.

As kneading conditions, when additives other than the vulcanizing agent and the vulcanization accelerator are blended, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30 seconds. -30 minutes, preferably 1-30 minutes.
When blending a vulcanizing agent and a vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. A composition containing a vulcanizing agent and a vulcanization accelerator is usually used after vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

The tan δ peak temperature (Tg) of the rubber composition (after vulcanization) of the present invention is preferably −16 ° C. or higher, more preferably −15 ° C. or higher. There exists a possibility that grip performance may deteriorate that it is less than -16 degreeC. The upper limit of the tan δ peak temperature (Tg) of the rubber composition of the present invention (after vulcanization) is not particularly limited, but is preferably less than -8 ° C, more preferably less than -10 ° C. If it is −8 ° C. or higher, fuel economy and wear resistance may be deteriorated.
The tan δ peak temperature (Tg) is a value obtained by the measurement method described in Examples described later.

By adjusting the compounding ratio of the rubber composition, the tan δ peak temperature (Tg) of the rubber composition can be adjusted to −16 ° C. or higher. For example, the tan δ peak temperature (Tg) of the rubber composition can be increased by (1) increasing the SBR content with a high styrene content, (2) reducing the BR content, and the like.

The rubber composition of the present invention can be used as a tire rubber composition for each member of a tire, and among them, it can be suitably used as a tread rubber composition.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of each tire member such as a tread at an unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The pneumatic tire of the present invention is suitably used as a passenger car tire, truck / bus tire, motorcycle tire, high-performance tire, and the like, and particularly preferably as a high-performance tire. The pneumatic tire obtained by the present invention is excellent in grip performance on a dry road surface.
In addition, the high performance tire in this specification is a tire that is particularly excellent in grip performance on a dry road surface, and is a concept that includes a competition tire used for a competition vehicle.

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

[Carbon black production equipment]
A raw material introduction zone comprising an inner diameter of 500 mm having an air introduction duct and a combustion burner, a length of 1750 mm, a combustion zone having a length of 1750 mm, an inner diameter of 55 mm having a raw material nozzle penetrating from the periphery, and a narrow diameter portion having a length of 700 mm, A carbon black production facility in which a rear reaction zone having an inner diameter of 200 mm and a length of 2700 mm equipped with a quench device was sequentially joined was used.
[Production conditions] (Furnace method)
Using this production facility, carbon black was produced using natural gas as a fuel, using oils and petroleum hydrocarbons whose characteristics are shown in Table 1 as raw material oils, and other conditions shown in Table 2 as other conditions. Table 2 shows the yield and various characteristics of the carbon black obtained in each production example. Incidentally, various characteristics of carbon black were measured by the above-described methods. Further, the carbon blacks obtained in Production Examples 2-5 and 7-14 correspond to the carbon black (1). Note that the carbon black obtained by Production Example 12-14 had a poor yield, and carbon black that could be evaluated was not obtained. Therefore, the value of the amount of the raw material oil in the production conditions could not be confirmed. The measurement of various characteristics of black and the test for blending carbon black described later into the rubber composition were not performed.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
SBR: NS116R manufactured by Nippon Zeon Co., Ltd. (S-SBR, vinyl content: 60% by mass, styrene content: 20% by mass)
Carbon black: Carbon black silica obtained by Production Examples 1 to 11: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by Degussa
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Diana Process AH-24 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Zinc oxide stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd .: Stearic acid “Kashiwa” manufactured by NOF Corporation
Anti-aging agent: Ozonon 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Seiko Chemical Co., Ltd.
Sulfur: Sulfur powder vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. 1: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator 2: Soxinol D (1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

Examples and Comparative Examples In accordance with the formulation shown in Tables 3 and 4, using a BP Banbury mixer, BR 20 parts by mass, SBR 80 parts by mass, carbon black (carbon black shown in Tables 3 and 4), silica, silane coupling An agent, 25 parts by mass of oil, 2 parts by mass of zinc oxide, 2 parts by mass of stearic acid, and 2 parts by mass of an anti-aging agent were kneaded for 3 minutes at 150 ° C. to obtain a kneaded product. Next, 1.5 parts by mass of sulfur, 2.0 parts by mass of vulcanization accelerator 1 and 2.0 parts by mass of vulcanization accelerator 2 were added to the obtained kneaded material, and an open roll was used. The mixture was kneaded under conditions for 5 minutes to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 12 minutes to obtain a vulcanized rubber composition.

The following evaluation was performed using the obtained vulcanized rubber composition. Each test result is shown in Tables 3 and 4. In addition, the reference comparative example of Table 3 was set as Comparative Example 1, and the reference comparative example of Table 4 was set as Comparative Example 2.

(Abrasion resistance)
Using a LAT tester (Laboratory Abbreviation and Skid Tester), the volume loss of each vulcanized rubber composition was measured under the conditions of a load of 50 N, a speed of 20 km / h, and a slip angle of 5 °. The amount was set to 100 and displayed as an index (wear resistance index). It shows that it is excellent in abrasion resistance, so that a numerical value is large.

(Tan δ peak temperature, low exothermicity)
A test piece of a predetermined size was prepared from the obtained vulcanized rubber composition, and using an viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the initial strain was 10%, the dynamic strain was 0.5%, and the frequency was 10 Hz. And a temperature dispersion curve of tan δ at a temperature of −100 to 100 ° C. under the conditions of an amplitude of ± 0.25% and a heating rate of 2 ° C./min, and the temperature corresponding to the largest tan δ value in the temperature distribution curve is the tan δ peak It was temperature.
In addition, the loss tangent (tan δ) of each formulation was measured under the conditions of a temperature of 50 ° C., an initial strain of 10%, and a dynamic strain of 2%, and the tan δ of the reference comparative example was set to 100. Index display (low exothermic index). It shows that low exothermic property (rolling resistance characteristic) is excellent, so that an index | exponent is large. A good index was determined when the index was 95 or higher.
(Low exothermic index) = (tan δ of reference comparative example) / (tan δ of each formulation) × 100

From Tables 3 and 4, in Examples in which carbon black (1) and a specific amount of specific silica were blended, the wear resistance could be improved while maintaining or improving good low heat generation, and the wear resistance and low It was possible to achieve both high exothermic properties.

Comparison between Comparative Examples 3, 2, 4 and Example 7 shows that when only carbon black (1) is used as a filler, or carbon black other than carbon black (1) and a specific amount of specific silica are used in combination. Compared with the case where carbon black (1) and a specific amount of specific silica are used in combination, the improvement effect of the wear balance and the performance balance of wear resistance and low heat build-up is more than an addition. It was found that (synergistic effect) can be obtained.

Claims (12)

In a method for producing a rubber composition comprising a step of kneading a rubber component, one or more types of carbon black, and silica,
At least one of the carbon blacks has an average boiling point T (° C.) and a specific gravity D (60/60 ° F.) when compared with water of 60 ° F. as a raw material oil for producing the carbon black. A carbon black obtained by using a raw material oil having a BMCI value calculated by the following formula of 150 or less and an aliphatic hydrocarbon ratio of 30% by mass or more,
The silica has a nitrogen adsorption specific surface area of 40 to 400 m ² / g,
The manufacturing method of the rubber composition whose content of the said silica is 1-120 mass parts in the said rubber composition with respect to 100 mass parts of said rubber components.
BMCI = 48640 / (T + 273) + 473.7D-456.8 Carbon obtained by using at least one of the carbon blacks as a raw material oil for producing the carbon black having a BMCI value of 95 or more and an aliphatic hydrocarbon ratio of 60% by mass or less The method for producing a rubber composition according to claim 1, wherein the rubber composition is black. 10. The method for producing a rubber composition according to claim 1, wherein 10% by mass or more of the aliphatic hydrocarbon contained in the raw material oil is an aliphatic hydrocarbon derived from an animal or vegetable oil or a modified product thereof. The manufacturing method of the rubber composition of any one of Claims 1-3 in which the said raw material oil contains tall oil. The method for producing a rubber composition according to any one of claims 1 to 4, wherein the carbon black is carbon black produced by a furnace method . In a rubber composition comprising a rubber component, one or more carbon blacks, and silica,
At least one of the carbon blacks has a maximum frequency diameter (Dmod) of the distribution curve of the Stokes equivalent diameter as an aggregate characteristic of 43 to 79 nm, and the ratio of the half-value width (ΔD50) of the distribution curve to Dmod ( ΔD50 / Dmod). ) Is carbon black of 0.78 to 2.5 ,
The silica has a nitrogen adsorption specific surface area of 40 to 400 m ² / g,
The rubber composition whose content of the said silica is 1-120 mass parts in the said rubber composition with respect to 100 mass parts of said rubber components. A vulcanized rubber composition obtained by vulcanizing the claims 6 Symbol mounting of the rubber composition, vulcanized rubber composition tanδ peak temperature of -16 ° C. or higher. 6. Symbol mounting of the rubber composition is used as a rubber composition for a tire. A pneumatic tire produced using the rubber composition according to claim 8. Vulcanizing the rubber composition obtained by the method for producing a rubber composition according to claim 1,
The manufacturing method of the vulcanized rubber composition whose tan-delta peak temperature of the vulcanized rubber composition obtained by this process is -16 degreeC or more. The method for producing a rubber composition according to any one of claims 1 to 5, wherein the rubber composition is used as a tire rubber composition. The manufacturing method of a pneumatic tire including the process of producing a pneumatic tire using the rubber composition obtained by the manufacturing method of the rubber composition of Claim 11.