JP2013043900A - Rubber composition for tire, method for producing the same and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for tires, capable of balancing both low fuel cost and durability and giving a good wet gripping performance; to provide a method for producing the same, and to provide a pneumatic tire using the rubber composition for tires.SOLUTION: The rubber composition for tires is obtained by kneading a rubber component, spherical composite particles comprising two or more kinds of polyorgano siloxanes and silica, and then kneading the obtained master batch with a silane coupling agent.

Description

The present invention relates to a rubber composition for tires, a method for producing the same, and a pneumatic tire using the rubber composition.

Conventionally, in order to reinforce rubber, reinforcing fillers such as carbon black and silica are blended in a tire rubber composition. When carbon black is blended, it is possible to obtain a rubber composition having good processability and excellent durability such as abrasion resistance, but the temperature dependency of tire physical properties is increased and the heat generation property is high. Thus, there is room for improvement in that the rolling resistance of the tire increases. On the other hand, when silica is uniformly dispersed in the rubber composition, the temperature dependence of the tire properties is reduced, wet grip performance is improved, heat generation is reduced, and rolling resistance is low (low fuel consumption). A rubber composition for tires having excellent properties can be obtained. For this reason, a technique for blending silica is attracting attention.

However, silica has (1) poor compatibility compared to carbon black, (2) high self-aggregation and is not easily dispersed, (3) durability of the resulting rubber composition (wear resistance and There is room for improvement in that the crack growth resistance is poor. Therefore, there is a demand for a method that can achieve both low fuel consumption and durability. Patent Document 1 describes a method of blending a specific deproteinized natural rubber to obtain a rubber composition excellent in fuel efficiency and durability. However, provision of other methods is also demanded. .

JP 2005-47993 A

The present invention solves the above-mentioned problems, achieves both low fuel consumption and durability, and provides a tire rubber composition capable of obtaining good wet grip performance, a method for producing the same, and a pneumatic tire using the tire rubber composition The purpose is to provide.

The present invention relates to a tire rubber composition obtained by kneading a rubber component, spherical composite particles containing two or more polyorganosiloxanes, and silica, and kneading the obtained master batch and a silane coupling agent. Related to things.

The two or more polyorganosiloxanes preferably have different organic groups.

The content of the spherical composite particles is 5 to 70 parts by mass and the content of the silica is 5 to 100 parts by mass with respect to 100 parts by mass of the total rubber component, and the total content of the spherical composite particles and the silica is 100. It is preferable that content of the said silane coupling agent with respect to a mass part is 2-15 mass parts.

The master batch is preferably obtained by kneading carbon black together with the rubber component, the spherical composite particles, and the silica.

It is preferable that the content of the carbon black is 5 to 50 parts by mass and the total content of the spherical composite particles, the silica and the carbon black is 10 to 150 parts by mass with respect to 100 parts by mass of the total rubber component.

The temperature for kneading the masterbatch and the silane coupling agent is preferably 120 to 160 ° C., and the time for kneading is preferably 3 to 10 minutes.

It is preferable that the composition of the spherical composite particles changes stepwise or continuously from the particle center toward the surface.

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

The present invention also includes a first base kneading step for preparing the master batch by kneading the rubber component, the spherical composite particles and the silica, and a second base kneading step for kneading the master batch and the silane coupling agent. The manufacturing method of the said rubber composition containing these.

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

According to the present invention, for a tire obtained by kneading a rubber component, spherical composite particles containing two or more kinds of polyorganosiloxane, and silica, and kneading the obtained master batch and a silane coupling agent. Since it is a rubber composition and its manufacturing method, both low fuel consumption and durability (particularly wear resistance) can be achieved, and good wet grip performance can be obtained. Therefore, a pneumatic tire excellent in these performances can be provided by using the rubber composition in a tread or the like.

The rubber composition of the present invention is obtained by kneading a rubber component, spherical composite particles containing two or more types of polyorganosiloxane, and silica, and kneading the obtained master batch and a silane coupling agent. .

The spherical composite particles have a property of being highly compatible with a rubber component as compared with conventional fillers (reinforcing fillers) such as silica and carbon black. The spherical composite particles are kneaded with the rubber component and silica, and then the silane coupling agent is added and further kneaded, so that the spherical composite particles and silica are sufficiently dispersed in the rubber component. Because of the reaction, the dispersibility of silica can be improved. Moreover, since the said spherical composite particle has the reinforcement property equivalent to carbon black, favorable durability is acquired by mix | blending. These effects can improve fuel economy, durability, and wet grip performance in a well-balanced manner. Moreover, since silica can be easily dispersed, the processability is also excellent.

The rubber composition of the present invention includes, for example, a first base kneading step in which a rubber component, spherical composite particles containing two or more polyorganosiloxanes, and silica are kneaded to prepare a master batch, and the master batch and the silane cup. It can manufacture suitably by the manufacturing method including the 2nd base kneading process of kneading | mixing a ring agent.

(First base kneading process)
In this step, a rubber component, spherical composite particles containing two or more types of polyorganosiloxane, and silica are kneaded. The temperature and time for kneading these are not particularly limited, but are usually 80 to 160 ° C. and 3 to 10 minutes. Moreover, the kneading | mixing method can use the kneading machine used in general rubber industries, such as a Banbury mixer and an open roll.

The rubber component that can be used in the present invention is not particularly limited, and natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber ( CR, ethylene propylene diene rubber (EPDM), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), styrene isoprene butadiene rubber (SIBR), styrene isoprene rubber (SIR), and isoprene butadiene rubber. Diene rubbers may be used alone or in combination of two or more. Among these, NR and SBR are preferable, and NR and SBR are more preferably used in combination because high fuel economy, wear resistance, and wet grip performance can be achieved at a high level.

The NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like can be used.

The SBR is not particularly limited, and those generally used in the tire industry such as emulsion polymerization styrene butadiene rubber (E-SBR) and solution polymerization styrene butadiene rubber (S-SBR) can be used. Among these, from the viewpoint that the effect of improving fuel economy is great, modified SBR modified with a polyfunctional compound having two or more epoxy groups in the molecule and introduced with a hydroxyl group or an epoxy group is preferable. As such modified SBR, Asaprene E15 manufactured by Asahi Kasei Chemicals Corporation can be used.

The rubber composition finally obtained is kneaded in the first base kneading step in 100% by mass of all rubber components (total of rubber components used in all steps) because a good dispersion state of silica is obtained. The compounding amount of the rubber component is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 100% by mass.

The spherical composite particles used in the present invention contain two or more types of polyorganosiloxane. For the reason that the effects of the present invention can be obtained satisfactorily, the two or more polyorganosiloxanes preferably have different organic groups.

As the raw material for the spherical composite particles, two or more organic silicon compounds having a silicon atom in which 1 to 3 non-hydrolyzable groups and 3 to 1 alkoxyl groups are bonded are used. Examples of the organosilicon compound include the following general formula (I)
R ¹ _n Si (OR ² ) _4-n (I)
(In the general formula (I), R ¹ represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, The alkyl group may have a (meth) acryloyloxy group, an epoxy group or a glycidoxy group, R ² represents an alkyl group having 1 to 6 carbon atoms, n represents an integer of 1 to 3, and R ¹ represents If there are multiple, each R ¹ may be the same as each other or different, if OR ² there are a plurality, each OR ² may be the same or may be different from one another.)
The compound represented by these can be used.

The alkyl group for R ¹ may be linear, branched, or cyclic. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl Group, tert-butyl group, pentyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group and the like, and an alkyl group having 1 to 10 carbon atoms is preferable. Specific examples of the case where the alkyl group of R ¹ has a (meth) acryloyloxy group, an epoxy group or a glycidoxy group include a γ-acryloyloxypropyl group, a γ-methacryloyloxypropyl group, and a γ-glycidoxypropyl group. 3,4-epoxycyclohexyl group and the like.

The alkenyl group for R ¹ may be linear, branched or cyclic, and examples thereof include a vinyl group, an allyl group, a butenyl group, a hexenyl group, an octenyl group, and the like. Alkenyl groups are preferred.

Examples of the aryl group for R ¹ include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group, and an aryl group having 6 to 10 carbon atoms is preferable.

Examples of the aralkyl group for R ¹ include a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group, and the like, and an aralkyl group having 7 to 10 carbon atoms is preferable.

The alkyl group of R ² may be linear, branched or cyclic, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl. Group, tert-butyl group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group and the like, and an alkyl group having 1 to 3 carbon atoms is preferable.

R ¹ is preferably an alkyl group or an alkenyl group, and more preferably a methyl group or a vinyl group, because the effect of the present invention can be obtained satisfactorily. R ² is preferably a methyl group.

Examples of the silicon compound represented by the general formula (I) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltri Ethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyl Examples thereof include oxypropyltrimethoxysilane, dimethyldimethoxysilane, and methylphenyldimethoxysilane. Of these, methyltrimethoxysilane and vinyltrimethoxysilane can be preferably used.

The spherical composite particles are, for example, organosilicon compounds having a silicon atom in which 1 to 3 non-hydrolyzable groups and 3 to 1 alkoxyl groups are bonded, or a mixture of two or more, each having a different composition. A method of hydrolyzing and condensing a plurality of groups in two or more stages (Method 1), or an organosilicon compound having a silicon atom in which 1 to 3 non-hydrolyzable groups and 3 to 1 alkoxyl groups are bonded. A spherical composite particle precursor is prepared by a method (Method 2) in which two or more kinds are used, and an aqueous solution containing the organosilicon compound is hydrolyzed and condensed in one step while changing the composition continuously, It can be produced by firing the spherical composite particle precursor. According to the above (Method 1), spherical composite particles containing two or more types of polyorganosiloxane and having a composition that changes substantially stepwise from the particle center toward the surface can be obtained. On the other hand, according to the method (Method 2), spherical composite particles containing two or more types of polyorganosiloxane and having a composition that changes substantially continuously from the center of the particle toward the surface can be obtained.

First, the above (Method 1) will be described. The hydrolysis and condensation reaction in the above (Method 1) is preferably performed in a two-layer state without substantially mixing the above-mentioned organosilicon compound alone or a mixture of two or more and a solution containing ammonia and / or amine. The reaction is carried out at the interface while maintaining The solution containing ammonia and / or amine may be an aqueous solution or a mixed solution of water and an organic solvent. Hereinafter, this aqueous solution and mixed solution are also referred to as an aqueous solution.

The ammonia and amine function as a catalyst for hydrolysis and condensation reaction of the organosilicon compound. Here, as the amine, for example, monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine and the like can be used. Ammonia and amine may be used alone or in combination of two or more. However, ammonia is preferred because it is less toxic, easy to remove, and inexpensive.

The ammonia or amine is used as an aqueous solution or a mixed solution of water and an organic solvent. Here, as the organic solvent, those having high miscibility with water are preferable. For example, lower alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone, dimethyl ketone and methyl ethyl ketone; diethyl ether and dipropyl ether Ethers; and the like.

The amount of ammonia or amine used is not particularly limited, but it is preferably adjusted so that the pH of the lower aqueous layer before the reaction starts is in the range of 7.5 to 11.0. In addition, the reaction temperature depends on the kind of the organic silicon compound as a raw material, but generally may be in the range of 0 to 60 ° C.

Next, after the upper layer (organosilicon compound layer) has substantially disappeared, the second-stage hydrolysis is performed in the same manner as described above using an organic silicon compound having a composition different from that of the disappeared upper layer alone or a mixture of two or more. Then, a condensation reaction is performed, and further, if necessary, the same operation as described above is repeated a desired number of times using an organosilicon compound having a different composition alone or a mixture of two or more.

In the final hydrolysis and condensation reaction, after the upper layer disappears, ammonia and / or an amine is added to the reaction system and aged. This aging may be performed at the same temperature as in the reaction or may be performed at a slightly elevated temperature. After completion of ripening, the particles produced according to a conventional method are sufficiently washed, and then subjected to a classification treatment as necessary to remove maximal particles or minimal particles, followed by drying treatment. Although there is no restriction | limiting in particular as a classification processing method, The wet classification method which classifies using the sedimentation speed changes with particle sizes is preferable. What is necessary is just to perform a drying process at the temperature of the range of normal temperature-150 degreeC normally.

Next, the above (Method 2) will be described. In the hydrolysis and condensation reaction in the (Method 2), first, two or more aqueous solutions containing the organosilicon compound alone or two or more and having different compositions are prepared. Then, these aqueous solutions are continuously added to the other aqueous solutions in order at the same rate, and the final aqueous solution is continuously dropped at the same rate as described above into the aqueous solution containing ammonia and / or amine. . Specifically, for example, when organic silicon compound-containing aqueous solutions having different compositions (A), (B), (C) and (D) are prepared, (D) is continuously changed to (C) at the same rate. In addition, while adding (C) to (B) and further adding (B) to (A), the (A) is continuously added to an aqueous solution containing ammonia and / or amine at the same rate as above. Dripping into. After completion of the dropwise addition, the mixture is aged for about 1 to 4 hours, and subjected to hydrolysis and condensation reaction. The reaction temperature is usually in the range of 0 to 60 ° C. Next, ammonia and / or an amine are added to the reaction system and sufficiently aged. This aging may be performed at the same temperature as in the reaction or may be performed at a slightly elevated temperature.

Thereafter, the same operation as in the case of (Method 1) is performed to obtain a desired spherical composite particle precursor. According to this (Method 2), since the composition of the organosilicon compound-containing aqueous solution dropped into the reaction field is continuously changed, what is obtained by the method (Method 1) is substantially stepwise. A particle having a substantially continuous gradient structure is obtained while having a simple gradient structure. Further, since each organosilicon compound is dissolved in water and used as an aqueous solution, it is not affected by the difference in dissolution rate with respect to the solvent in the reaction field in particle formation. Therefore, it is easier to form a gradient composite structure than the two-layer reaction of (Method 1).

Thus, after obtaining the monodispersed spherical composite particle precursor, the spherical composite particles containing two or more kinds of polyorganosiloxanes having different organic groups are obtained by firing treatment. The firing temperature is usually in the range of 200 to 700 ° C. However, when there are only two types of polyorganosiloxane in the spherical composite particles, the polyorganosiloxane having a low pyrolysis temperature of the organic component is used. It is preferable that the temperature be higher than the thermal decomposition temperature and lower than the thermal decomposition temperature of the polyorganosiloxane having a high organic component thermal decomposition temperature. That is, it is preferable to set the temperature at which only the organic component of one of the two types of polyorganosiloxane is thermally decomposed. Moreover, this baking process can be performed in inert gas atmosphere, such as nitrogen gas. The firing time depends on the type of spherical composite particles, the firing temperature, and the like, and cannot be determined unconditionally, but is generally about 0.5 to 10 hours.

The average particle diameter of the spherical composite particles is preferably 1 μm or more, more preferably 2 μm or more, preferably 10 μm or less, more preferably 8 μm or less because the effect of the present invention can be obtained satisfactorily. The coefficient of variation (CV value) of the spherical composite particles is preferably 3% or less, more preferably 2% or less.
The average particle size of the spherical composite particles can be measured with a particle counter. The coefficient of variation of the spherical composite particles can be calculated from the following equation using the average particle diameter of the spherical composite particles and the standard deviation of the particle diameter measured with a particle counter.
Coefficient of variation (%) = [standard deviation of particle diameter (μm)] / [average particle diameter (μm)] × 100

In the finally obtained rubber composition, the amount of the spherical composite particles to be kneaded in the first base kneading step is 100% by mass in the total amount of the spherical composite particles because a good dispersion state of silica is obtained. , Preferably it is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is 100 mass%.

The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but 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 preferably 30 m ² / g or more, more preferably 100 m ² / g or more, and further preferably 150 m ² / g or more. If it is less than 30 m < ² > / g, there exists a tendency for a reinforcement effect to be small and for abrasion resistance to fall. Further, N ₂ SA of silica is preferably 220 m ² / g or less, more preferably 200 m ² / g or less. 220 m ² /
If it exceeds g, the dispersibility of silica is lowered, and there is a possibility that sufficient low fuel consumption, wear resistance and wet grip performance may not be obtained.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

In the finally obtained rubber composition, the amount of silica to be kneaded in the first base kneading step is preferably 90% by mass in 100% by mass of the total amount of silica because a good dispersion state of silica is obtained. As mentioned above, More preferably, it is 95 mass% or more, More preferably, it is 100 mass%.

In the first base kneading step, it is preferable to prepare a master batch by kneading carbon black together with the rubber component, the spherical composite particles, and the silica. That is, the master batch is preferably obtained by kneading carbon black together with the rubber component, the spherical composite particles, and the silica. Thereby, good durability is obtained.
Carbon black is not particularly limited, and carbon black commonly used in the tire industry can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 25 m ² / g or more, more preferably 45 m ² / g or more. If it is less than 25 m ² / g, sufficient reinforcing properties cannot be obtained, and sufficient wear resistance tends to be not obtained. The N ₂ SA of the carbon black is preferably 200 m ² / g or less, more preferably 100 m ² / g or less. If it exceeds 200 m ² / g, the fuel efficiency tends to deteriorate.
The nitrogen adsorption specific surface area of carbon black is a value measured according to JIS K 6217-2: 2001.

In the finally obtained rubber composition, the amount of carbon black to be kneaded in the first base kneading step is preferably 90% out of 100% by mass of the total amount of carbon black because a good dispersion state of silica is obtained. It is at least 95% by mass, more preferably at least 95% by mass, still more preferably 100% by mass.

From the viewpoint of preventing the spherical composite particles and silica from reacting with the silane coupling agent in an insufficiently dispersed state, it is preferable to reduce the amount of the silane coupling agent as much as possible in the first base kneading step. The blending amount of the silane coupling agent to be kneaded in the first base kneading step in the total amount of 100% by mass of the silane coupling agent is preferably 5% by mass or less, more preferably 1% by mass or less, and still more preferably 0% by mass ( Substantially not blended).

(Second base kneading process)
In this step, the master batch and the silane coupling agent obtained in the first base kneading step are kneaded. The kneading temperature is preferably 120 to 160 ° C., and the kneading time is preferably 3 to 10 minutes. Moreover, the kneading | mixing method can use the kneading machine used in general rubber industries, such as a Banbury mixer and an open roll.

The kind of the silane coupling agent in the present invention is not particularly limited, and a silane coupling agent that has been conventionally blended with rubber or plastic can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, Bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis ( 4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3- bird Toxisilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, Bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilyl Ethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetra Sulfides such as rufide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltri Mercapto series such as ethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl series such as vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltri Amino series such as methoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, Glycidoxy series such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-nitropropyltri Nitro-based compounds such as methoxysilane and 3-nitropropyltriethoxysilane, chloro-based compounds such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane These may be used, and these may be used alone or in combination of two or more. Among these, a sulfide-based silane coupling agent is preferable because good fuel economy, wear resistance, and wet grip performance can be obtained. Bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-tri More preferred is ethoxysilylpropyl) disulfide, and even more preferred is bis (3-triethoxysilylpropyl) disulfide.

In the finally obtained rubber composition, the amount of the silane coupling agent kneaded in the second base kneading step is 100% by mass of the total amount of the silane coupling agent because a good dispersion state of silica is obtained. , Preferably it is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is 100 mass%.

To the kneaded product obtained in the second base kneading step, a vulcanized or cross-linking agent, a vulcanized or cross-linking accelerator, etc. are added and kneaded, and the resulting unvulcanized rubber composition is vulcanized or By crosslinking, the rubber composition of the present invention is obtained.

In addition to the above-mentioned components, the rubber composition of the present invention can be blended with various additives generally blended as tire rubber compositions such as various oils, anti-aging agents, and plasticizers. The step of kneading these additives is not particularly limited, but in the final rubber composition, it is preferable to knead in the second base kneading step because a good dispersion state of silica is obtained.

Hereinafter, a preferable composition of the rubber composition of the present invention obtained by the above production method will be described.

In the rubber composition of the present invention obtained by the above production method and the like, the content of NR in 100% by mass of all rubber components is preferable because of high compatibility between low fuel consumption, wear resistance and wet grip performance. Is 5% by mass or more, more preferably 10% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less. For the same reason, the content of SBR in 100% by mass of the total rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, preferably 95% by mass or less, more preferably 90% by mass or less. It is.

In the rubber composition of the present invention obtained by the above production method or the like, the content of the spherical composite particles is preferably 5 parts by mass or more, more preferably 8 parts by mass or more with respect to 100 parts by mass of the total rubber component. . If the amount is less than 5 parts by mass, the dispersibility of silica is not sufficiently improved, and there is a possibility that the fuel economy, wear resistance and wet grip performance cannot be sufficiently improved. Further, the content of the spherical composite particles is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and still more preferably 50 parts by mass or less. When it exceeds 70 mass parts, there exists a possibility that abrasion resistance may fall.

In the rubber composition of the present invention obtained by the above production method, the silica content is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass with respect to 100 parts by mass of all rubber components. More than part by mass. If the amount is less than 5 parts by mass, sufficient fuel economy, wear resistance and wet grip performance tend not to be obtained. The content of silica is preferably 100 parts by mass or less, more preferably 90 parts by mass or less. When the amount exceeds 100 parts by mass, the workability deteriorates due to re-aggregation of silica, and the wear resistance also tends to decrease.

In the rubber composition of the present invention obtained by the above production method or the like, the content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 4 parts per 100 parts by mass in total of the spherical composite particles and silica. It is at least 6 parts by mass, more preferably at least 6 parts by mass. If it is less than 2 parts by mass, the dispersibility of silica is not sufficiently improved, and there is a possibility that the fuel economy, wear resistance and wet grip performance cannot be sufficiently improved. The content of the silane coupling agent is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 10 parts by mass or less. If it exceeds 15 parts by mass, the wear resistance may be reduced.

When carbon black is blended, in the rubber composition of the present invention obtained by the above production method or the like, the content of carbon black is preferably 5 parts by mass or more, more preferably 10 parts per 100 parts by mass of all rubber components. More than part by mass. If the amount is less than 5 parts by mass, sufficient reinforcement cannot be obtained, and sufficient wear resistance may not be obtained. The content of carbon black is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. When it exceeds 50 mass parts, there exists a possibility that the improvement effect of low-fuel-consumption property may be impaired.

In the rubber composition of the present invention obtained by the above production method, the total content of the spherical composite particles, silica and carbon black is preferably 10 parts by mass or more, more preferably 100 parts by mass of the total rubber components. 50 parts by mass or more, more preferably 80 parts by mass or more, and particularly preferably 95 parts by mass or more. If the amount is less than 10 parts by mass, sufficient fuel economy, wear resistance, and wet grip performance tend not to be obtained. The total content is preferably 150 parts by mass or less, and more preferably 140 parts by mass or less. If it exceeds 150 parts by mass, fuel economy and wear resistance tend to deteriorate.

The rubber composition of this invention can be used for each member of a tire, and can be used conveniently for a tread (especially cap tread).

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, if necessary, a rubber composition containing various additives is extruded in accordance with the shape of each member of a tire such as a tread at an unvulcanized stage, and is processed on a tire molding machine by a normal method. After forming and bonding together with other tire members to form an unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

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

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
NR: RSS # 3
SBR: Asaprene E15 manufactured by Asahi Kasei Co., Ltd. (modified S-SBR modified with a polyfunctional compound having two or more epoxy groups in the molecule and introduced with a hydroxyl group or an epoxy group)
Silica: VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g)
Carbon black: N351 (N ₂ SA: 69 m ² / g) manufactured by Cabot Japan
Spherical composite particles (A): produced in the following Production Example 1 spherical composite particles (B): produced in the following Production Example 1 spherical composite particles (C): produced in the following Production Example 2 Silane coupling agent: Si266 manufactured by Degussa ( Bis (3-triethoxysilylpropyl) disulfide)
Process oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: Zinc oxide sulfur manufactured by Mitsui Mining & Smelting Co., Ltd .: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller CZ manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Production Example 1)
In a 1300 milliliter plastic container, 250 milliliters of an aqueous solution containing 0.2 milliliter / liter of 1 mol / liter ammonia water was placed, and this was stirred with a magnetic stirrer at about 60 rpm while vinyltrimethoxysilane (VTMS). 5 g was slowly added, and a VTMS layer was formed on the upper layer. Next, this was stirred at room temperature until the upper layer completely disappeared, and then a homogeneous mixture of 3.3 g of VTMS and 1.7 g of methyltrimethoxysilane (MTMS) was slowly added, and a mixture of VTMS and MTMS was added to the upper layer. A layer was formed and further stirred until the upper layer disappeared completely. Next, a homogenous mixture of 2.5 g of VTMS and 2.5 g of MTMS, a homogenous mixture of 1.7 g of VTMS and 3.3 g of MTMS, and 5 g of MTMS were sequentially added in the same manner as described above, and the silicon compound was gradually added. The polymethylsilsesquioxane (PMSO) / polyvinylsilsesquioxane (PVSO) particles were formed by changing the composition. After disappearance of the MTMS layer added last, the mixture was stirred as it was for about 2 hours, and then 2 ml of 25 mass% ammonia water was added to solidify the formed particles. Furthermore, after aging overnight, the particles obtained by centrifugation are put into methanol and decanted, and then the fine particles formed at the time of solidification by adding aqueous ammonia are removed and dried at about 50 ° C. Thus, a dry powder (spherical composite particle precursor) was obtained. As a result of measuring the particle size distribution and particle size of the obtained spherical composite particle precursor with a coal counter, only one large particle size peak was observed, the average particle size was 3.232 μm, and the CV value was 1.55%. It was confirmed that the monodisperse particles were obtained. Moreover, it was confirmed by the measurement of the infrared absorption spectrum of this spherical composite particle precursor that it is a composite particle of PVSO and PMSO. Next, the spherical composite particle precursor thus obtained was fired at 280 ° C. or 400 ° C. for 2 hours in a nitrogen atmosphere to obtain spherical composite particles (A) and (B) shown in Table 1 below. It was.

(Production Example 2)
In a 300 ml plastic container, 225 ml of ion exchanged water and 25 g of VTMS were placed and stirred until uniform to obtain a partially hydrolyzed liquid (i). Similarly, 225 ml of ion-exchanged water and 25 g of MTMS were placed in a 300 ml plastic container, and stirred until uniform to obtain a partially hydrolyzed liquid (ii). On the other hand, 500 ml of ion exchange water and 0.2 ml of 1 mol / liter ammonia water were placed in a 1000 ml plastic container and stirred until uniform to obtain a liquid (iii). Next, while continuously dropping the partial hydrolyzed liquid (ii) onto the partial hydrolyzed liquid (i) being stirred, the partial hydrolyzed liquid (i) is added to the liquid (iii) being stirred at the same speed. It dripped and the dripping from the final partial hydrolysis liquid (i) to the liquid (iii) was performed over 5 hours. After the completion of the dropwise addition, the mixture was stirred for about 2.5 hours, and then 2 ml of 25% by mass ammonia water was added to solidify the formed particles. Thereafter, the same operation as in Production Example 1 was performed to obtain a dry powder (spherical composite particle precursor). The obtained spherical composite particle precursor was measured for particle size distribution and particle size with a Coulter counter. As a result, only one large particle size peak was observed, the average particle size was 2.20 μm, and the CV value was 2.01%. It was confirmed that the monodisperse particles were obtained. Moreover, it was confirmed by the infrared absorption spectrum that it is a composite particle of PMSO and PVSO. Next, the spherical composite particle precursor thus obtained was baked for 2 hours at a temperature of 350 ° C. in a nitrogen atmosphere to obtain spherical composite particles (C) shown in Table 1 below.

(Examples and Comparative Examples)
The material shown in step (1) of Table 2 was put into a 1.7 L closed banbury mixer, kneaded for 4 minutes until the temperature reached 140 ° C, and discharged when the temperature reached 145 ° C. The total kneading time was 5 minutes. (First base kneading process)
Next, the master batch obtained in the step (1) and the material shown in the step (2) in Table 2 are put into a 1.7 L closed Banbury mixer and further kneaded for about 3 minutes until the temperature reaches 150 ° C. And it released when it reached 155 ° C. The total kneading time was 5 minutes. (Second base kneading process)
Next, the material shown in step (3) of Table 2 was further added to the kneaded product obtained in step (2), and kneaded for about 2 minutes with an open roll to obtain an unvulcanized rubber composition. (Finish kneading process)
The obtained unvulcanized rubber composition was press vulcanized with a 0.5 mm thick mold at 170 ° C. for 20 minutes to obtain a vulcanized rubber composition.

The following evaluation was performed using the vulcanized rubber composition. The results are shown in Table 2.

(Pain effect (silica dispersibility))
Using RPA2000 manufactured by Alpha Technology, the strain dependence of the storage elastic modulus of the vulcanized rubber composition was measured under the conditions of a measurement temperature of 110 ° C. (preheating 1 minute), a frequency of 6 cpm, and an amplitude of 0.28 to 10%. The value of the storage elastic modulus when the strain amount was 0.56% was determined. The results are displayed as an index with the value of Comparative Example 1 being 100 (Pain effect index). The smaller the index, the smaller the number of poorly dispersed filler particles, and the better the dispersibility of the filler. In this example, since the proportion of silica in the filler is large, the Payne effect index mainly indicates the dispersibility of silica.

(Viscoelasticity test)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was measured under conditions of a temperature of 60 ° C., an initial strain of 10%, and a dynamic strain of 2%. The tan δ of Comparative Example 1 was set to 100, and the index was expressed by the following formula (rolling resistance index). A larger index indicates lower rolling resistance and better fuel efficiency.
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

(Abrasion resistance test)
Using a Lambourn abrasion tester, the Lambourn abrasion amount of the vulcanized rubber composition was measured under the conditions of a temperature of 20 ° C., a slip ratio of 20% and a test time of 2 minutes. Then, the volume loss amount was calculated from the measured amount of Lambourn wear, the volume loss amount of Comparative Example 1 was set to 100, and the volume loss amount of each formulation was displayed as an index (wear resistance index) by the following formula. The larger the index, the higher the wear resistance and the better the durability.
(Abrasion resistance index) = (Volume loss amount of each formulation) / (Volume loss amount of Comparative Example 1) × 100

(Wet grip performance test)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was measured at a temperature of 0 ° C., an initial strain of 10%, and a dynamic strain of 5%. The tan δ of Comparative Example 1 was set to 100, and the index was expressed by the following formula (wet grip performance index). It shows that it is excellent in wet grip performance, so that an index | exponent is large.
(Wet grip performance index) = (tan δ of each formulation) / (tan δ of Comparative Example 1) × 100

From Table 2, Examples obtained by kneading a rubber component, spherical composite particles containing two or more kinds of polyorganosiloxane, and silica, and kneading the obtained master batch and a silane coupling agent are as follows: Silica was well dispersed, and all of the fuel efficiency, wear resistance and wet grip performance were improved. On the other hand, Comparative Examples 2 to 4 contain the above spherical composite particles, but since the entire amount of the silane coupling agent is kneaded in the first base kneading step, the dispersibility of silica can be sufficiently improved. However, the fuel economy, wear resistance, and wet grip performance were inferior to the corresponding examples. In Comparative Example 5 in which the amount of silica was increased instead of the spherical composite particles, the dispersibility of silica was low, and the fuel efficiency was greatly deteriorated.

Claims (10)

Kneading a rubber component, spherical composite particles containing two or more polyorganosiloxanes, and silica;
A rubber composition for tires obtained by kneading the obtained master batch and a silane coupling agent. The tire rubber composition according to claim 1, wherein the two or more kinds of polyorganosiloxanes have different organic groups. The content of the spherical composite particles is 5 to 70 parts by mass with respect to 100 parts by mass of all rubber components, and the content of the silica is 5 to 100 parts by mass.
The rubber composition for a tire according to claim 1 or 2, wherein the content of the silane coupling agent with respect to 100 parts by mass of the total content of the spherical composite particles and the silica is 2 to 15 parts by mass. The tire rubber composition according to any one of claims 1 to 3, wherein the master batch is obtained by kneading carbon black together with the rubber component, the spherical composite particles, and the silica. The content of the carbon black is 5 to 50 parts by mass with respect to 100 parts by mass of all rubber components, and the total content of the spherical composite particles, the silica and the carbon black is 10 to 150 parts by mass. Rubber composition for tires. The tire rubber composition according to any one of claims 1 to 5, wherein a temperature at which the master batch and the silane coupling agent are kneaded is 120 to 160 ° C, and a time for kneading is 3 to 10 minutes. The tire rubber composition according to any one of claims 1 to 6, wherein the composition of the spherical composite particles changes stepwise or continuously from the particle center toward the surface. The tire rubber composition according to any one of claims 1 to 7, which is used as a tread rubber composition. A first base kneading step of kneading the rubber component, the spherical composite particles and the silica to prepare the master batch;
The manufacturing method of the rubber composition for tires in any one of Claims 1-8 including the 2nd base kneading process which knead | mixes the said masterbatch and the said silane coupling agent. The pneumatic tire produced using the rubber composition in any one of Claims 1-8.