JP2011026392A - Rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition suitable for various rubber products which can improve abrasion resistance and tear resistance and can simultaneously further reduce rolling resistance, and to provide a tire using the rubber composition. <P>SOLUTION: The rubber composition suitable for tire treads and the like is produced by compounding a rubber component with hydrated silica and carbon black. The hydrated silica satisfies expression: A<SB>ac</SB>≥-0.76×(CTAB)+274, wherein CTAB (m<SP>2</SP>/g) is the cetyltrimethylammonium bromide adsorption specific surface area of the hydrated silica; A<SB>ac</SB>(nm) is the primary aggregate diameter mode determined by an acoustic grain size distribution measurement method. The carbon black is obtained by a specific process, and has a dibutyl phthalate (DBP) absorption of 40 to 180 cm<SP>3</SP>/100 g, a nitrogen adsorption specific surface area (N<SB>2</SB>SA) of 40 to 300 m<SP>2</SP>/g, a specific tinctorial power (TINT) of 50 to 150% and a toluene colored transmittance of ≥90%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the rubber composition, and in particular, various rubber products capable of further reducing rolling resistance while improving durability such as wear resistance and tear resistance. The present invention relates to a rubber composition suitable for a tire member and a tire using the same.

Conventionally, carbon black has been used as a reinforcing filler for rubber. This is because carbon black can impart high wear resistance to the rubber composition.
In recent years, with the social demands for resource and energy saving, low heat generation of tire rubber has been required at the same time for the purpose of saving fuel consumption of automobiles. When trying to reduce heat generation by using carbon black alone, it may be possible to reduce the amount of carbohen black filling or use a large particle size, but in either case reinforcement, abrasion resistance, It is known that it is inevitable that the grip performance on a wet road surface is lowered.

  On the other hand, silica is known as a filler to improve low heat build-up (for example, Patent Documents 1 to 4), but silica tends to aggregate particles due to hydrogen bonding of silanol groups that are surface functional groups. In addition, the silanol group is not good wettability with the rubber molecule because of the —OH group having hydrophilicity, and the silica is not well dispersed in the rubber. In order to improve this, it is necessary to lengthen the kneading time. Further, since the silica is not sufficiently dispersed in the rubber, the rubber composition has a high Mooney viscosity, and has disadvantages such as inferior processability such as extrusion. Furthermore, since the surface of the silica particles is acidic, when the rubber composition is vulcanized, a basic substance used as a vulcanization accelerator is adsorbed, vulcanization is not sufficiently performed, and the elastic modulus does not increase. It also had the disadvantage of.

  In order to remedy these drawbacks, silane coupling agents have been developed, but the silica dispersion has not yet reached a sufficient level, and it is difficult to obtain particularly good industrial dispersion of silica particles. there were. Therefore, it has been practiced to knead silica whose surface has been treated with a hydrophobizing agent to promote the reaction of the silane coupling agent (Patent Document 1).

  Patent Document 5 discloses the use of hydrophobic precipitated silicic acid. However, since precipitated silicic acid that has been completely hydrophobized is used, there is a surface silanol group that reacts with the silane coupling agent. As a result, there was a drawback that the rubber could not be sufficiently reinforced. Furthermore, in order to enhance the low heat build-up, silica is increased in particle size. However, by increasing the particle size, the specific surface area of silica is reduced and the reinforcing property is deteriorated. Patent Document 6 discloses the use of silica having a special shape, but the current situation is that the low heat build-up and wear resistance of the rubber composition are not sufficient.

  Further, as a method of reducing the rolling resistance of the tire, as described above, the rubber composition having a reduced hysteresis loss is reduced by using a carbon black or by using a lower carbon black. Although methods used for tread rubber are known, simple weight loss of the carbon black used can reduce the wear resistance of the rubber composition. In addition, the rolling resistance can be improved by increasing the proportion of the polybutadiene rubber in the rubber component or increasing the elasticity of the rubber composition. In this case, however, the tear resistance of the rubber composition is lowered. There is a problem in the point.

JP-A-6-248116 JP-A-7-70369 JP-A-8-245838 JP-A-3-252431 JP-A-6-157825 JP 2006-37046 A

  The present invention has been made in view of the above-described problems of the prior art, and is intended to solve this problem. A rubber composition capable of further reducing rolling resistance while improving durability such as wear resistance and tear resistance. To provide things. Another object of the present invention is to provide a tire using such a rubber composition, which is applied to a tire member and in which wear resistance, tear resistance and rolling resistance are highly balanced.

  As a result of intensive studies to achieve the above object, the present inventor has formulated hydrous silicic acid having specific physical properties and carbon black with a small amount of tar components present on the surface, particularly polycyclic aromatic components, into the rubber component. The present inventors have found that the rubber composition further reduces the rolling resistance while improving the durability such as wear resistance and tear resistance, thereby completing the present invention.

That is, the rubber composition of the present invention, the rubber component to, hydrous silicic acid, and dibutyl phthalate (DBP) absorption number of at 40~180cm ³ / 100g, a nitrogen adsorption specific surface area _(N 2 SA) 40 to 300 m ² / G, a rubber composition comprising carbon black having a specific coloring power (TINT) of 50 to 150% and a toluene coloring transmittance of 90% or more,
The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) of the hydrated silicic acid and the mode value A _ac (nm) of the diameter of the primary aggregate obtained by acoustic particle size distribution measurement are expressed by the following formula (I ):
A _ac ≧ −0.76 × (CTAB) +274 (I)
While satisfying
The carbon black uses a reaction apparatus in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, generates high-temperature combustion gas in the combustion gas generation zone, and then feeds the raw material in the reaction zone To form a reaction gas stream containing carbon black, and then quenching the reaction gas stream by a multistage rapid refrigerant introduction means in the reaction stop zone to terminate the reaction, The toluene coloring permeability in the multistage rapid refrigerant introduction means is represented by the following formulas (II) and (III):
10 <X <40 (II)
90 <Z <100 (III)
[In the formula, X is the toluene coloring permeability (%) of carbon black after introduction of the first quenching medium from the raw material introduction position, and Z is the toluene coloring permeability (%) of carbon black after the last quenching medium introduction. Is satisfied].
In addition, the toluene coloring permeability of carbon black after the last rapid refrigerant introduction is synonymous with the toluene coloring permeability of carbon black after manufacture.
In the carbon black, the relationship between the nitrogen adsorption specific surface area and the toluene coloring permeability is represented by the following formula (IV):
0.0283 × A × (100−B) ≦ 40 (IV)
Carbon black satisfying [wherein A is the nitrogen adsorption specific surface area (m ² / g) and B is the toluene coloring transmittance (%)) is preferable.
Furthermore, the hydrous silicic acid used in the present invention is characterized by having a structure (primary aggregation) that can be represented by the above-described index, and as described later, an aqueous alkali silicate solution such as sodium silicate. Is obtained by a method according to a method of precipitating and precipitating hydrous silicic acid by neutralizing with a mineral acid such as sulfuric acid, that is, a so-called precipitation method of producing hydrous silicic acid.

In another preferred embodiment of the rubber composition of the present invention, the hydrous silicic acid has its loss on ignition (mass loss% when heated at 750 ° C. for 3 hours) and weight loss on heating (mass when heated at 105 ° C. for 2 hours). (% Decrease)
(Loss on ignition)-(Lose on heating) ≤ 3 (V)
It is preferable to satisfy.
The hydrous silicic acid has a primary aggregate diameter mode determined by acoustic particle size distribution measurement of 1 μm or less, and the hydrous silicic acid has a CTAB of 50 to 250 m ² / g. preferable.
Furthermore, the rubber component is at least one rubber selected from natural rubber and / or diene synthetic rubber, and 10 to 150 parts by mass of hydrous silicic acid may be blended with 100 parts by mass of the rubber component. preferable.
It is preferable to mix | blend 1-20 mass% of the compounding quantity of a hydrous silicic acid with respect to the said hydrous silicic acid, and it represents with the following general formula (VI)-(VIII) as a silane coupling agent. It is preferable to contain at least one selected from the group consisting of the above compounds. Such a rubber composition containing hydrous silicic acid is highly compatible with low heat buildup and wear resistance.
_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ·· (VI)
[Wherein, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, m is an integer of 1 to 3, and a is 1 An integer of ˜9, b is an integer of 1 or more, and may have a distribution. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ],
Compound represented by the following general formula (VII):
A _m B _3-m Si— (CH ₂ ) _c —Y (VII)
[In the formula, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Y is a mercapto group, a vinyl group, an amino group, It is a glycidoxy group or an epoxy group, m is an integer of 1 to 3, and c is an integer of 0 to 9. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]
And a compound represented by the following general formula (VIII):
A _m B _3-m Si— (CH ₂ ) _a —S _b —Z (VIII)
[In the formula, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Z is a benzothiazolyl group, N, N-dimethylthio It is a carbamoyl group or a methacryloyl group, m is an integer of 1 to 3, a is an integer of 1 to 9, and b is an integer of 1 or more and may have a distribution. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]

  In a preferred example of the rubber composition of the present invention, the amount of the carbon black is 55 parts by mass or less with respect to 100 parts by mass of the rubber component. In this case, the low exothermic property of the rubber composition can be improved.

［式中、Ｒ^１は、それぞれ独立して炭素数１〜１２のアルキル基、シクロアルキル基又は
アラルキル基である］で表される置換アミノ基、及び下記式（Ｖ）：

［式中、Ｒ^２は、３〜１６のメチレン基を有するアルキレン基、置換アルキレン基、オキシアルキレン基又はＮ−アルキルアミノ−アルキレン基を示す］で表される環状アミノ基で表される環状アミノ基が更に好ましく、ヘキサメチレンイミノ基が特に好ましい。これらの窒素含有官能基は、カーボンブラック、シリカ等の種々の充填剤を配合したゴム組成物において充填剤分散効果が高く、充填剤の補強効果を大幅に向上できる。 In the rubber composition of the present invention, the nitrogen-containing functional group of the modified conjugated diene polymer is preferably a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, and pyridyl group. (IV):

[Wherein R ¹ is each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, or an aralkyl group], and the following formula (V):

[Wherein R ² represents an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group], and a cyclic amino group represented by a cyclic amino group A group is further preferred, and a hexamethyleneimino group is particularly preferred. These nitrogen-containing functional groups have a high filler dispersion effect in a rubber composition containing various fillers such as carbon black and silica, and can greatly improve the reinforcing effect of the filler.

In another preferred embodiment of the rubber composition of the present invention, the conjugated diene polymer is a polybutadiene rubber, particularly preferably a polybutadiene rubber having at least one hexamethyleneimino group.
In another preferred embodiment of the rubber composition of the present invention, the natural rubber is obtained from a latex obtained by partially deproteinizing a protein in natural rubber latex by a mechanical separation method. A natural rubber having a nitrogen content of more than 0.1% by mass and 0.4% by mass or less. In this case, hysteresis loss can be reduced while maintaining the durability of the rubber composition.
Furthermore, the tire of the present invention is characterized by using the rubber composition as a tread rubber.

  According to the present invention, the rubber component is blended with a specific structural hydrous silicic acid and a tar component present on the surface, particularly carbon black with a small amount of polycyclic aromatic components, so that the wear resistance, tear resistance, etc. Thus, it is possible to provide a rubber composition suitable for a rubber product and a tire member that can further reduce rolling resistance while improving durability. Moreover, the tire which used this rubber composition and was highly balanced in abrasion resistance, tear resistance, and rolling resistance can be provided.

It is a vertical front explanatory drawing of an example of the carbon black manufacturing furnace for manufacturing carbon black used for the rubber composition of the present invention. Hydrous silicic acid A~G obtained in each production example, is a graph showing the relationship between the alignment commercially available two CTAB and _{A ac.}

Hereinafter, embodiments of the present invention will be described in detail.
The rubber composition of the present invention, the rubber component to, hydrous silicic acid, and dibutyl phthalate (DBP) absorption number of at 40~180cm ³ / 100g, a nitrogen adsorption specific surface area _(N 2 SA) 40 to 300 m ² / g And a rubber composition comprising carbon black having a specific coloring power (TINT) of 50 to 150% and a toluene coloring transmittance of 90% or more,
The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) of the hydrated silicic acid and the mode value A _ac (nm) of the diameter of the primary aggregate obtained by acoustic particle size distribution measurement are expressed by the following formula (I ):
A _ac ≧ −0.76 × (CTAB) +274 (I)
While satisfying
The carbon black uses a reaction apparatus in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, generates high-temperature combustion gas in the combustion gas generation zone, and then feeds the raw material in the reaction zone To form a reaction gas stream containing carbon black, and then quenching the reaction gas stream by a multistage rapid refrigerant introduction means in the reaction stop zone to terminate the reaction, The toluene coloring permeability in the multistage rapid refrigerant introduction means is represented by the following formulas (II) and (III):
10 <X <40 (II)
90 <Z <100 (III)
[In the formula, X is the toluene coloring permeability (%) of carbon black after introduction of the first quenching medium from the raw material introduction position, and Z is the toluene coloring permeability (%) of carbon black after the last quenching medium introduction. It is characterized by satisfying the relationship.

The structural hydrous silicic acid used in the present invention can be confirmed by the fact that the characteristic values measured by a method generally measured with silica or carbon black satisfy the following relationship.
That is, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) and the diameter A _ac (nm) of the mode of the number of primary aggregates determined by acoustic particle size distribution measurement are represented by the following formula (I)
A _ac ≧ −0.76 × (CTAB) +274 (I)
Preferably, the loss on ignition (mass loss% when heated at 750 ° C. for 3 hours) and the weight loss on heating (mass loss% when heated at 105 ° C. for 2 hours) are represented by the following formula (V):
(Loss on ignition)-(Lose on heating) ≤ 3 (V)
Hydrous silicic acid satisfying

Cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is the specific surface area (m ² / g) of hydrous silicic acid calculated from the amount of cetyltrimethylammonium bromide adsorbed on the hydrous silicic acid surface.
CTAB can be measured according to the method described in ASTM D3765-92. Since the method described in ASTM D3765-92 is a method for measuring CTAB of carbon black, it is slightly modified. That is, a standard solution of cetyltrimethylammonium bromide (hereinafter abbreviated as CE-TRAB) is prepared without using a carbon black standard product, and thereby a hydrous silicate OT (sodium di-2-ethylhexylsulfosuccinate) solution is prepared. The specific surface area is calculated from the adsorption amount of CE-TRAB, assuming that the adsorption cross-sectional area per molecule of CE-TRAB on the hydrous silicate surface is 0.35 nm ² .

Precipitated silica used in the present invention, CTAB is 50 to 250 m ² / g, it is desirable that preferably 100 to 200 m ² / g. When the CTAB is less than 50 m ² / g, the storage elastic modulus of the rubber composition is remarkably lowered, and when it is more than 250 m ² / g, the viscosity of the rubber composition when unvulcanized may be increased.

As the particle size of the hydrous silicic acid, the diameter (acoustic particle size distribution diameter) measured by an acoustic particle size distribution measuring device is an index of the development of the structure. The hydrous silicic acid particles include those in which finely sized particles are primary aggregated and those that are slightly secondary aggregated.
The measurement with an acoustic particle size distribution measuring apparatus is carried out by dispersing a hydrous silicic acid 0.01 M KCl aqueous solution with ultrasonic waves for 5 minutes to remove bubbles and destroying secondary aggregates. The distribution of the particle size and the number of particles of hydrous silicic acid primary aggregates is obtained. Of these, the most frequently occurring particle diameter is A _ac (nm).
A _ac ≧ −0.76 × (CTAB) +274 (I)
When both are satisfied, both the low heat build-up and the wear resistance of the rubber composition are improved. When _Aac does not satisfy this condition, either or both of low heat buildup and wear resistance are reduced. Further, _Aac is preferably 1 μm or less. When it is larger than 1 μm, hydrous silicic acid becomes a fracture nucleus, and the mechanical properties of the rubber composition may be impaired.

Furthermore, the difference between the decrease in mass when the hydrous silicic acid used in the present invention is heated (%) and the decrease in mass when heated (%) is,
(Loss on ignition)-(Lose on heating) ≤ 3 (V)
It is preferable that
The weight loss by heating and the weight loss by ignition are performed in accordance with the test method for the compounding agent for JIS K6220-1 rubber, and the weight loss by heating can usually improve the low exothermic property of the rubber composition.
The weight loss% when heated at 105 ± 2 ° C. for 2 hours and the loss on ignition are usually the weight loss% when ignited at 750 ± 25 ° C. for 3 hours.

The hydrous silicic acid used in the present invention is produced according to the method for producing hydrous silicic acid by precipitation method. For example, sodium silicate and sulfuric acid are placed in a reaction vessel preliminarily filled with a certain amount of warm water while controlling pH and temperature, and added for a certain period of time to obtain a hydrous silicate slurry.
Subsequently, the hydrated silicate slurry is filtered and washed by a filter capable of cake washing such as a filter press to remove the by-product electrolyte, and then the obtained hydrated silicate cake is slurried, and a spray dryer or the like It is dried and manufactured using a dryer.
The amount of the structural hydrous silicic acid used in the present invention will be described later.

In the present invention, it is preferable to use a silane coupling agent. The silane coupling agent reacts with the silanol group remaining on the surface of the hydrous silicic acid and the rubber component polymer, and acts as a bonding bridge between the hydrous silicic acid and the rubber to form a reinforcing phase.
The silane coupling agent used in the present invention is preferably at least one selected from the group consisting of compounds represented by the following general formula.

_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ··· (VI)
[Wherein, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, m is an integer of 1 to 3, and a is 1 An integer of ˜9, b is an integer of 1 or more, and may have a distribution. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]

A _m B _3-m Si— (CH ₂ ) _c —Y (VII)
[Wherein, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Y is a mercapto group, a vinyl group, an amino group, It is a glycidoxy group or an epoxy group, m is an integer of 1 to 3, and c is an integer of 0 to 9. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]

A _m B _3-m Si— (CH ₂ ) _a —S _b —Z (VIII)
_Wherein A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Z is a benzothiazolyl group, N, N-dimethylthio It is a carbamoyl group or a methacryloyl group, m is an integer of 1 to 3, a is an integer of 1 to 9, and b is an integer of 1 or more and may have a distribution. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]

  Specifically, as the silane coupling agent represented by the general formula (VI), bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (3-trimethoxysilylpropyl) tetrasulfide, bis- ( 3-methyldimethoxysilylpropyl) tetrasulfide, bis- (3-triethoxysilylethyl) tetrasulfide, bis- (3-triethoxysilylpropyl) disulfide, bis- (3-trimethoxysilylpropyl) disulfide, bis- ( 3-triethoxysilylpropyl) trisulfide,

  Examples of the silane coupling agent represented by the general formula (VII) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane,

  Examples of the silane coupling agent represented by the general formula (VIII) include 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-trimethoxy And silylpropylmethacryloyl monosulfide.

  As for the usage-amount of a silane coupling agent, 1-20 mass% is preferable with respect to the quantity of a hydrous silicic acid. If the amount used is less than 1% by mass, a sufficient coupling effect may not be obtained, and if it exceeds 20% by mass, gelation of the polymer may be caused.

Next, the carbon black used in the present invention, dibutyl phthalate (DBP) absorption number of at 40~180cm ³ / 100g, a nitrogen adsorption specific surface area _(N 2 SA) in 40 to 300 m ² / g, the ratio tinting strength (TINT ) Is 50 to 150%, the toluene color permeability is 90% or more, and the relationship between the nitrogen adsorption specific surface area and the toluene color permeability needs to include carbon black satisfying the above formula (I). .
Generally, in a rubber composition in which carbon black is blended with a rubber component, particularly a rubber component containing a modified conjugated diene polymer having a nitrogen-containing functional group, the dispersibility of the carbon black with respect to the rubber component is improved and extended. Since the hysteresis loss of the rubber component is reduced, wear resistance and rolling resistance can be improved. However, when a rubber component obtained by blending natural rubber with the modified conjugated diene polymer is used, it is necessary to further improve the effect of reducing hysteresis loss. This is because natural rubber obtained by a normal production method has a high loss tangent (tan δ) due to the remaining non-rubber component contained in the natural rubber latex, and the exothermic reduction effect may be low. is there. In contrast, the carbon black used in the rubber composition of the present invention has a sufficiently low tar content on the surface because the DBP absorption amount, N ₂ SA, TINT, and toluene color permeability satisfy the above-described ranges. As a result of efficient formation of the rubber and rubber molecules, and further the structural hydrous silicic acid, the wear resistance and low heat build-up of the rubber composition can be improved. Furthermore, in the rubber composition of the present invention, carbon black is obtained by using a modified conjugated diene polymer having a nitrogen-containing functional group as a rubber component together with carbon black having a small tar component present on the surface and structural hydrous silicic acid. Since the dispersibility of black is further greatly improved, it is possible to further reduce the hysteresis loss in the rubber composition while further sufficiently exerting the reinforcing effect of carbon black. Therefore, when the natural rubber is blended with the modified conjugated diene polymer, the rubber composition of the present invention has a rubber product, a tire member, and a tire equipped with the tire member. Property and rolling resistance can be further sufficiently improved.

In the rubber composition of the present invention, as the rubber component, at least one rubber selected from natural rubber and / or diene synthetic rubber can be used. Preferably, a modified conjugated diene polymer is used.
The modified conjugated diene polymer that can be used is not particularly limited as long as it has one or more nitrogen-containing functional groups, and is generally known to have an affinity for fillers such as carbon black and silica. Other functional groups may be included, for example, a functional group containing silicon or a functional group containing tin. Here, as the conjugated diene polymer, a copolymer of a conjugated diene compound and an aromatic vinyl compound and a homopolymer of a conjugated diene compound are preferable. Specifically, polyisoprene rubber (IR), styrene- Examples include synthetic rubbers such as butadiene copolymer rubber (SBR), polybutadiene rubber (BR), isobutylene isoprene rubber (IIR), halogenated butyl rubber, styrene-isoprene copolymer rubber (SIR), and chloroprene rubber (CR). Polybutadiene rubber is particularly preferred. These conjugated diene polymers may be used alone or in a blend of two or more.

  The conjugated diene polymer can be obtained, for example, by polymerizing a monomer conjugated diene compound alone or a mixture of a monomer aromatic vinyl compound and a conjugated diene compound. In the rubber composition for a tread of the present invention, since it is necessary to introduce at least one nitrogen-containing functional group into the molecule of the conjugated diene polymer, (1) a monomer is used as a polymerization initiator. And a method for producing a polymer having a polymerization active site, and then modifying the polymerization active site with various nitrogen-containing modifiers, or (2) a polymerization initiator having a nitrogen-containing functional group as a monomer. It is preferable to obtain it by the method of polymerizing using.

  The polymerization initiator used for the synthesis of the modified conjugated diene polymer is preferably an organic lithium compound, more preferably hydrocarbyl lithium and a lithium amide compound. When an organic lithium compound is used as the polymerization initiator, the aromatic vinyl compound and the conjugated diene compound are polymerized by anionic polymerization. When hydrocarbyl lithium is used as the polymerization initiator, a polymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained. On the other hand, when a lithium amide compound is used as the polymerization initiator, a polymer having a nitrogen-containing functional group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained, and the polymer is a nitrogen-containing modifier. It can be used as a modified conjugated diene polymer in the present invention without modification. In addition, the usage-amount of a polymerization initiator has the preferable range of 0.2-20 mmol per 100g of monomers.

  Examples of the hydrocarbyl lithium include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl-phenyl. Examples include lithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and among these, ethyllithium, n-propyllithium, isopropyllithium, n-butyl Alkyl lithium such as lithium, sec-butyl lithium, tert-octyl lithium and n-decyl lithium is preferable, and n-butyl lithium is particularly preferable.

  On the other hand, the lithium amide compounds include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium Dihexylamide, lithium diheptylamide, lithium dioctylamide, lythym-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium methylbutyramide, lithium ethylbenzylamide, Lithium methyl phenethyl amide, etc., among which lithium hexamethylene imide, lithium pyrrolidide, lithium Umupiperijido, lithium heptamethylene imide, preferably lithium amide compound of the cyclic such as lithium dodecamethylene imide, lithium hexamethylene imide and lithium pyrrolidide are particularly preferable.

The lithium amide compound is represented by the formula: Li-AM [wherein AM is a substituted amino group represented by the following formula (IV) or a cyclic amino group represented by the following formula (V)]. Modification in which at least one nitrogen-containing functional group selected from the group consisting of a substituted amino group represented by formula (IV) and a cyclic amino group represented by formula (V) is introduced by using a lithium amide compound A conjugated diene polymer is obtained. For example, when lithium hexamethyleneimide is used, a modified conjugated diene polymer into which at least one hexamethyleneimino group is introduced is obtained.

In the formula (IV), R ¹ is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, or an aralkyl group. Specifically, a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, Preferable examples include 3-phenyl-1-propyl group and isobutyl group. R ¹ may be the same or different from each other. On the other hand, in the formula (V), R ² is an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group. Here, the substituted alkylene group includes a mono- to octa-substituted alkylene group, and examples of the substituent include a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a bicycloalkyl group, and an aryl group. Groups and aralkyl groups. R ² is specifically preferably a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, or the like.

The method for producing a conjugated diene polymer using the polymerization initiator is not particularly limited. For example, the polymer is obtained by polymerizing a monomer in a hydrocarbon solvent inert to the polymerization reaction. Can be manufactured. Here, as the hydrocarbon solvent inert to the polymerization reaction, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis -2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, and the like may be used. These may be used alone or in combination of two or more. May be. Moreover, you may implement the said polymerization reaction in presence of a randomizer. The polymerization is preferably carried out by solution polymerization, and the concentration of the monomer in the polymerization reaction solution is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass. Further, the polymerization mode is not particularly limited, and may be batch type or continuous type. Furthermore, the reaction temperature of the polymerization reaction is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 130 ° C.

  Further, in modifying the polymerization active site of the polymer having the polymerization active site with a modifier, the modifier used is a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group or pyridyl. Nitrogen-containing compounds having groups are preferred. Suitable nitrogen-containing compounds as the modifier include isocyanate compounds such as diphenylmethane diisocyanate, crude MDI, trimethylhexamethylene diisocyanate, tolylene diisocyanate, 4- (dimethylamino) benzophenone, 4- (diethylamino) benzophenone, 4-dimethylamino. Examples include benzylideneaniline, 4-dimethylaminobenzylidenebutylamine, dimethylimidazolidinone, N-methylpyrrolidone and the like.

Furthermore, when the polymerization active site of a polymer obtained by polymerization with a polymerization initiator having a nitrogen-containing functional group is modified with a modifying agent, when a coupling agent is used as the modifying agent, the resulting modified conjugated diene heavy polymer is obtained. A plurality of nitrogen-containing functional groups are introduced into the coalesced molecule, and the dispersibility of the carbon black can be greatly improved. Specific examples of the coupling agent include SnCl ₄ , R ³ SnCl ₃ , R ³ ₂ SnCl ₂ , R ³ ₃ SnCl, SiCl ₄ , R ³ SiCl ₃ , R ³ ₂ SiCl ₂ , R ³ ₃ SiCl, etc. Specific examples of R ³ include a methyl group, an ethyl group, an n-butyl group, a neophyll group, a cyclohexyl group, an n-octyl group, and a 2-ethylhexyl group. In particular, SnCl ₄ and SiCl ₄ are preferable as the coupling agent.

  The modification reaction of the polymerization active site by the modifying agent is preferably performed by a solution reaction, and the solution may contain a monomer used at the time of polymerization. The reaction mode of the modification reaction is not particularly limited, and may be a batch type or a continuous type. Furthermore, the reaction temperature of the modification reaction is not particularly limited as long as the reaction proceeds, and the reaction temperature of the polymerization reaction may be employed as it is. In addition, the usage-amount of modifier | denaturant has the preferable range of 0.25-3.0 mol with respect to 1 mol of polymerization initiators used for manufacture of a polymer, and the range of 0.5-1.5 mol is still more preferable.

  The natural rubber used as a rubber component in the rubber composition of the present invention is inherently excellent in elasticity, processability, fracture characteristics, low heat build-up, etc., so various rubber products such as belt conveyor members, tire members, especially tread rubber Suitable for applications. However, depending on the method for producing natural rubber, the physical properties inherent to natural rubber may be adversely affected by the effects of non-rubber components present in natural rubber latex. Therefore, as a suitable natural rubber used in the rubber composition for a tread of the present invention, the total nitrogen content obtained from a latex obtained by partially deproteinizing proteins in natural rubber latex by a mechanical separation method is 0. Natural rubber exceeding 1 mass% and 0.4 mass% or less is mentioned. Such natural rubber has a total nitrogen content that is an indicator of protein content by removing proteins present in natural rubber latex by mechanical means such as centrifugation without using chemical means such as enzymatic treatment. Is adjusted to the above specified range, and as a result, the low heat build-up can be improved without impairing the physical properties inherent in natural rubber.

  The natural rubber suitable for the rubber composition of the present invention is obtained by, for example, partially dividing the latex before coagulation by a mechanical separation method, preferably a centrifugal concentration method, so that the total nitrogen content of the solid rubber is within a certain range. Manufactured by deproteinization. Here, when deproteinization is performed by a method other than mechanical separation, the protein in the solid rubber is reduced, but at the same time, active ingredients such as tocotrienol having an anti-aging action are lost. Aging resistance may be reduced.

  The natural rubber suitable for the rubber composition of the present invention can control the total nitrogen content by adjusting, for example, the centrifugal separation conditions (rotation speed, time, etc.) of the natural rubber latex that is the raw material. If the total nitrogen content in the natural rubber is 0.1% by mass or less, the heat aging resistance may be lowered. On the other hand, if it exceeds 0.4% by mass, the effect of reducing the heat build-up is not sufficiently obtained.

  The natural rubber suitable for the rubber composition of the present invention can be obtained by subjecting the obtained natural rubber latex to coagulation and drying treatment after partial deproteinization treatment. The natural rubber latex used as a raw material is not particularly limited, and a field latex, a commercially available latex, or the like can be used.

  The rubber component of the rubber composition of the present invention preferably contains natural rubber and the modified conjugated diene polymer, and more preferably contains 70% by mass or more of the natural rubber and the modified conjugated diene polymer in total. In particular, the rubber component preferably contains 10 to 50% by mass of the modified conjugated diene polymer. When the content of the modified conjugated diene polymer in the rubber component is less than 10% by mass, a further improvement effect of carbon black dispersibility cannot be obtained sufficiently. On the other hand, when the content exceeds 50% by mass, workability decreases. There is a case. In the case where a rubber component other than natural rubber and a modified conjugated diene polymer is included, a general rubber component used in the rubber industry can be blended.

  When a modified conjugated diene polymer is used as the rubber component of the rubber composition of the present invention, the mass ratio (A / B) between the natural rubber (A) and the modified conjugated diene polymer (B) is 90. It is preferably / 10 to 50/50, and more preferably 80/20 to 50/50. Here, when the ratio of the modified conjugated diene polymer to the total of the natural rubber and the modified conjugated diene polymer is less than 10% by mass (that is, when the ratio of the natural rubber exceeds 90% by mass), the carbon black The improvement in dispersibility is insufficient, and the low-loss effect may not be sufficiently obtained. On the other hand, when the proportion of the modified conjugated diene polymer exceeds 50% by mass (that is, the proportion of natural rubber is 50% by mass). If it is less than%, the tear resistance may be insufficient, and the workability may be reduced.

Carbon black used in the rubber composition of the present invention, dibutyl phthalate (DBP) absorption is 40~180cm ³ / 100g, preferably from 70~170cm ³ / 100g. Is less than the DBP absorption of carbon black is 40 cm ^3/100 g, it is impossible to express the minimum required tensile stress as a tread rubber ^composition, it exceeds 180cm 3/100 g, to ensure the minimum required elongation I can't.

Carbon black used in the rubber composition of the present invention, the nitrogen adsorption specific surface area _(N 2 SA) is 40 to 300 m ² / g, is preferably from 70 to 250 ² / g, in 70~170m ² / g More preferably. When the nitrogen adsorption specific surface area of carbon black is less than 40 m ² / g, the minimum strength (tensile strength) required as a rubber composition for tread cannot be expressed, and when it exceeds 300 m ² / g, the rubber composition The dispersibility in it cannot be ensured sufficiently, and the wear resistance of the rubber composition is lowered.

  The carbon black used in the rubber composition of the present invention has a specific coloring power (TINT) of 50 to 150%, preferably 90 to 145%. If the specific coloring power of the carbon black is less than 50%, when the rubber composition is used in a tread, the tire cannot exhibit strength and abrasion resistance that can be practically used, and if it exceeds 150%, the viscosity of the rubber Increases significantly, making it difficult to obtain a composition.

  The carbon black used for the rubber composition of the present invention has a toluene coloring transmittance of 90% or more, and preferably 95% or more. When the toluene coloring transmittance of carbon black is less than 90%, the tar content present on the surface of carbon black, especially the aromatic component, is large, and the rubber composition cannot be sufficiently reinforced, and the wear resistance of the rubber composition, etc. Decreases.

The carbon black used in the rubber composition of the present invention has a nitrogen adsorption specific surface area and a toluene coloring transmittance as the absolute values represented by the following formula (IV):
0.0283 × A × (100−B) ≦ 40 (IV)
[Wherein, A is a nitrogen adsorption specific surface area (m ² / g) and B is a toluene color permeability (%)], and the following formula (XI):
0.0283 × A × (100−B) ≦ 20 (XI)
It is preferable to satisfy the following formula (XII):
0.0283 × A × (100−B) ≦ 8 (XII)
It is more preferable to satisfy the relationship (in formulas (XI) and (XII), A and B have the same meanings as in formula (IV)). Carbon black having a left side of more than 40 in formula (IV) has a large tar content on the surface, so that the rubber composition cannot be sufficiently reinforced and wear resistance is reduced.

  The carbon black uses a reaction device in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, generates high-temperature combustion gas in the combustion gas generation zone, and then generates the reaction zone. After the raw material is sprayed and introduced to form a reaction gas stream containing carbon black, the reaction gas stream is rapidly cooled by a multistage rapid refrigerant introduction means in the reaction stop zone to terminate the reaction. Hereinafter, the method for producing the carbon black will be described in detail with reference to FIG.

  FIG. 1 is a longitudinal front view of an example of a carbon black production furnace for producing carbon black used in the rubber composition of the present invention. The interior of the carbon black production furnace 1 has a structure in which a combustion zone, a reaction zone, and a reaction stop zone are connected in series, and the whole is covered with a refractory. Moreover, the carbon black production furnace 1 rectifies the oxygen-containing gas introduced from the outer periphery of the furnace head and the oxygen-containing gas introduction pipe by the oxygen-containing gas introduction pipe as a combustion zone using a rectifying plate, and combustible fluid. An oxygen-containing gas introduction cylinder to be introduced into the introduction chamber, and a fuel oil spray device introduction pipe that is installed on the central axis of the oxygen-containing gas introduction cylinder and introduces combustion hydrocarbons into the combustible fluid introduction chamber. In the combustion zone, high-temperature combustion gas is generated by combustion of combustion hydrocarbons.

  The carbon black production furnace 1 includes, as a reaction zone, a condensing chamber in which a cylinder gradually converges, a raw material oil introducing chamber including four raw material oil spray ports on the downstream side of the converging chamber, and a reaction chamber on the downstream side of the raw material oil introducing chamber. 10. The feed oil spray port sprays feed hydrocarbons into the hot combustion gas stream from the combustion zone. In the reaction zone, the raw material hydrocarbon is sprayed into the high-temperature combustion gas stream, and the raw material hydrocarbon is converted into carbon black by incomplete combustion or thermal decomposition reaction.

  The carbon black production furnace 1 includes a reaction continuation / cooling chamber 11 having a multistage rapid refrigerant introduction means 12 as a reaction stop zone. The multistage rapid refrigerant introduction means 12 sprays a rapid refrigerant such as water on the high-temperature combustion gas flow from the reaction zone. In the reaction stop zone, the high-temperature combustion gas flow is quenched by the quenching refrigerant to terminate the reaction. The carbon black production furnace 1 may further include a device for introducing a gas body in the reaction zone or the reaction stop zone. Here, as the “gas body”, air, a mixture of oxygen and hydrocarbon, a combustion gas obtained by a combustion reaction thereof, or the like can be used. In this way, in the production of carbon black, the average reaction temperature and residence time in each zone until the reaction gas flow enters the reaction stop zone are controlled, and the toluene coloring permeability of carbon black at each stage is set to a desired value. By adjusting the value, carbon black used in the rubber composition of the present invention can be obtained.

  Next, each zone in the carbon black production furnace 1 will be described. The combustion zone is a region where a high-temperature gas flow is generated by the reaction of fuel and air, and this downstream end is the point at which the feedstock is introduced into the reactor (the most upstream when introduced at multiple locations) ). The reaction zone refers to the multistage quench water spray means 12 in the reaction continuation / cooling chamber 11 from the point where the raw material hydrocarbon is introduced (the most upstream in the case of a plurality of positions) (these means are the reaction continuation / cooling chamber). 11 can be inserted and removed freely, and the use position is selected according to the type of product to be produced and the characteristics thereof) to the point of operation (introducing a cooling medium such as water). That is, when the raw material oil is introduced through the raw material oil spraying port and the water is introduced by the multistage rapid refrigerant introduction means 12, the region between these becomes the reaction zone. The reaction stop zone refers to a zone below (on the right side in FIG. 1) the point where the quenching water injection spray means is operated. In FIG. 1, the name of the reaction continuation / cooling chamber 11 is used because the reaction zone is from the raw material introduction time point to the operation time point of the quenching water injection spray means for stopping the reaction, and the reaction stop zone is thereafter. This is because the cold water introduction position may move depending on the required carbon black performance.

  The carbon black obtained by the above production method needs to satisfy the relationship of the above formulas (II) and (III). In FIG. 1, X is the toluene coloring permeability (%) of carbon black after introduction of the rapid refrigerant from the first rapid refrigerant introduction means 12 -X, and Z is the final rapid refrigerant introduction means 12. -Toluene coloring permeability (%) of carbon black after rapid refrigerant introduction by -Z. Here, if the carbon black obtained by the above production method satisfies the relationship of the above formulas (II) and (III), the particle size and surface physical properties of the carbon black are determined by defining the toluene coloring transmittance step by step. Balance can be achieved, reinforcing property can be improved, and wear resistance can be improved.

As described above, carbon black having such properties can be obtained by controlling the reaction temperature and residence time. For example, the residence time in the zone from when the raw material is sprayed into the reaction zone until the first quenching medium is introduced is t ₁ (seconds), and the average reaction temperature in this zone is T ₁ (° C.). And the residence time in the zone from the introduction of the first quenching medium to the introduction of the quenching medium by the second quenching medium introducing means (12-Y in FIG. 1) is t ₂ (seconds). The average reaction temperature in this zone is T ₂ (° C.), and the residence time in the zone from the introduction of the second sudden refrigerant body to the introduction of the last sudden refrigerant body (that is, the reaction stop zone) When the residence time in the zone until the passage is t ₃ (second) and the average reaction temperature in this zone is T ₃ (° C.), the residence time and the average reaction temperature are represented by the following formula (XIII) and formula (IVX) and formula (VX):
2.00 ≦ α1 ≦ 5.00 (XIII)
5.00 ≦ α2 ≦ 9.00 ・ ・ ・ ・ ・ ・ (IVX)
−2.5 1 × (α1 + α2) + 85.0 ≦ β ≦ 90.0 (VX)
Used in the rubber composition of the present invention by being controlled so as to satisfy the relationship [wherein α1 = t ₁ × T ₁ , α2 = t ₂ × T ₂ , β = t ₃ × T ₃ ] Carbon black can be obtained with certainty.

The carbon black production furnace 1 has a structure in which thermocouples can be inserted into an arbitrary number of locations in order to monitor the temperature in the furnace. To calculate the average reaction temperature _{T 1,} T 2, _{T 3,} at each step (each band), at least two positions, preferably it is preferable to measure the temperature of 3-4 points. Further, the residence times t ₁ , t ₂ , and t ₃ are calculated by calculating the volume of the introduced reaction gas fluid by a known thermodynamic calculation method and calculating by the following formula. Note that the increase in volume due to the decomposition reaction of the feedstock oil and the rapid cooling medium is ignored.
Residence time t ₁ (sec) = reactor passage volume from raw material hydrocarbon introduction position to first quenching medium introduction position (m ³ ) / reaction gas fluid volume (m ³ / sec)
Residence time t ₂ (sec) = reactor passing volume (m ³ ) / reaction gas fluid volume (m ³ / sec) from the first abrupt refrigerant introduction position to the introduction of the second abrupt refrigerant
Residence time t ₃ (sec) = reactor passage volume (m ³ ) / reaction gas fluid volume (m ³ / sec) from the second abrupt refrigerant introduction position to the last abrupt refrigerant introduction

  The rubber composition of the present invention is formed by blending 55 parts by mass or less, preferably 10 to 55 parts by mass of the carbon black with respect to 100 parts by mass of the rubber component. If the blending amount of the carbon black is less than 10 parts by mass, the reinforcing property of the rubber composition cannot be sufficiently ensured. On the other hand, if it exceeds 55 parts by mass, the dispersibility of the carbon black decreases, Wear resistance, tear resistance, and heat resistance may be reduced. Further, the rubber composition is further reinforced by blending the structural water-containing silicic acid (silica) in the range of 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component with respect to the compounding amount of the carbon black. Property (abrasion resistance) can be ensured, and furthermore, the hysteresis loss of the rubber composition can be greatly reduced. That is, it is possible to achieve both a low loss property and a high level of reinforcement (wear resistance) of the rubber composition.

The rubber composition of the present invention includes the rubber component, preferably a rubber component containing natural rubber and the modified conjugated diene polymer, carbon black having the above characteristics, hydrous silicic acid having the above structure, and a silane coupling agent. In addition, compounding agents usually used in the rubber industry, such as softeners, anti-aging agents, vulcanization accelerators, vulcanization accelerators, vulcanizers, etc., are within the range that does not impair the purpose of the present invention. It can select and mix | blend suitably. As these compounding agents, commercially available products can be suitably used.
In the rubber composition of the present invention, the rubber component is blended with carbon black having the above characteristics, the structural hydrous silicic acid, and various compounding agents appropriately selected as necessary, and an open kneading such as a roll. Rubber composition suitable for various rubber products, for example, rubber products such as belt conveyor members, tire members, etc., obtained by kneading using a closed kneader such as a machine or Banbury mixer Can be manufactured.

The tire of the present invention is characterized by using the rubber composition described above as a rubber member, preferably a tread rubber of a tire tread that serves as a contact surface with a road surface, and is particularly suitable as a heavy load tire.
In the tire of the present invention, when the above rubber composition is used as a tread rubber, the wear resistance, tear resistance and rolling resistance are extremely balanced. The tire of the present invention is not particularly limited except that the above rubber composition is used for the tread, and can be produced according to a conventional method. Moreover, as gas with which this tire is filled, inert gas, such as nitrogen, argon, helium other than normal or the air which adjusted oxygen partial pressure, can be used.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to the following Example at all.
In the following Examples, Comparative Examples, etc., production examples of modified polybutadiene rubber (HMI-BR) used as a rubber component and production examples of partially deproteinized natural rubber (PNR) are shown.
Moreover, while showing the manufacture example of the hydrous silicic acid of this invention, its physical property is shown in following Table 1, etc., the manufacturing example of the carbon black of this invention and its physical property are shown in following Table 2, Table 3, etc.

<Example of production of modified polybutadiene rubber (HMI-BR)>
Add about 283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine to an about 900 mL pressure-resistant glass container that has been dried and purged with nitrogen, and further n-butyl. After 0.57 mmol of lithium (BuLi) was added, polymerization was carried out in a hot water bath at 50 ° C. equipped with a stirrer for 4.5 hours. The polymerization conversion rate at this time was almost 100%. Next, 0.100 mmol of tin tetrachloride as a modifying agent (coupling agent) was quickly added to this polymerization reaction system, and the mixture was further stirred at 50 ° C. for 30 minutes to carry out a modification reaction. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the reaction, and further according to a conventional method. By drying, a modified polybutadiene rubber (HMI-BR) was obtained. The resulting HMI-BR had a vinyl bond content of the butadiene moiety of 14%, a glass transition temperature (Tg) of -95 ° C, and a coupling efficiency of 65%.

In addition, about the obtained HMI-BR, the peak of the highest molecular weight side with respect to the whole area of the molecular weight distribution curve by gel permeation chromatography (GPC) is calculated from the integration ratio of the ¹ H-NMR spectrum and the vinyl bond amount of the butadiene part. The coupling rate was determined from the area ratio, and the glass transition temperature was determined from the inflection point of the DSC curve.

<Example of production of partially deproteinized natural rubber (PNR)>
The natural rubber latex (CT-1) added with 0.4% by mass of ammonia was concentrated by centrifuging for 15 minutes at a rotational speed of 7500 rpm using a latex separator SLP-3000 (manufactured by Saito Centrifuge Co., Ltd.). Further, the concentrated latex was centrifuged at 7500 rpm for 15 minutes. The concentrated latex obtained was diluted to about 20% as a solid content, formic acid was added, and after standing overnight, the rubber content obtained by coagulation was dried at 110 ° C. for 210 minutes and partially deproteinized. Natural rubber (PNR) was produced. The total nitrogen content of the obtained PNR was 0.15% by mass as measured by the Kjeldahl method.

Physical Properties of Hydrous Silicic Acid (1) Measurement of Acoustic Particle Size Distribution Diameter A 0.01M KCl aqueous solution of each hydrous silicic acid is subjected to ultrasonic dispersion for 5 minutes to remove bubbles, and then an ultrasonic particle size distribution measuring device DT1200 ( Dispertion Technology Inc.) was used to measure the mode _a ac in diameters of primary aggregates of precipitated silica (nm).

(2) Measurement of CTAB The measurement was performed according to the method described in ASTM D3765-92. Since the method described in ASTM D3765-92 is a method for measuring CTAB of carbon black, some modifications were made. That is, a standard solution of cetyltrimethylammonium bromide (hereinafter abbreviated as CE-TRAB) is prepared without using IRB # 3 (83.0 m ² / g), which is a standard product of carbon black, and thereby containing water. The silicate OT (sodium di-2-ethylhexylsulfosuccinate) solution was standardized, and the adsorption cross section per molecule of CE-TRAB on the hydrous silicic acid surface was set to 0.35 nm ² from the adsorption amount of CE-TRAB. m ² / g) was calculated. This is because carbon black and hydrous silicic acid have different surfaces, and it is considered that there is a difference in the amount of CE-TRAB adsorbed even with the same surface area.

(3) Measurement of loss on heating and loss on ignition Weigh the hydrous silicic acid sample, heat the sample for 2 hours at 105 ± 2 ° C for loss on heating, and heat the sample for 3 hours at 750 ± 25 ° C for loss on ignition. Then, the mass was measured, and the difference from the sample mass before heating was expressed in% with respect to the mass before heating.

Production of hydrous silicic acid Production Example A
In a 180 L jacketed stainless steel reaction vessel equipped with a stirrer, 93 L of water and 0.6 L of sodium silicate aqueous solution (SiO ₂ 160 g / L, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 96 ° C. did. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 96 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, white turbidity started, and the viscosity increased at 47 minutes to form a gel solution. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 96 ° C. for 30 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. The obtained silicic acid slurry was filtered with a filter press and washed with water to obtain a wet cake. Next, the wet cake was made into a slurry using an emulsifier and dried with a spray dryer to obtain a wet method hydrous silicate A.

Production example B
Using the same container and raw materials as in Production Example A, 93 L of water and 0.6 L of an aqueous sodium silicate solution were added and heated to 90 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 90 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, white turbidity started, and the viscosity increased at 47 minutes to form a gel solution. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 90 ° C. for 30 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid B was obtained in the same manner as in Production Example A.

Production Example C
Using the same container and raw material as in Production Example A, 93 L of water and 0.6 L of sodium silicate aqueous solution were added and heated to 84 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 84 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, white turbidity started, and the viscosity increased at 48 minutes to form a gel solution. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 84 ° C. for 30 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid C was obtained in the same manner as in Production Example A.

Production Example D
Using the same container and raw materials as in Production Example A, 93 L of water and 0.6 L of an aqueous sodium silicate solution were added and heated to 90 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 90 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, white turbidity started, and the viscosity increased at 47 minutes to form a gel solution. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 90 ° C. for 60 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid D was obtained in the same manner as in Production Example A.

Production Example E
Using the same container and raw material as in Production Example A, 93 L of water and 0.6 L of an aqueous sodium silicate solution were added and heated to 78 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 78 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, white turbidity started, and the viscosity increased at 49 minutes to form a gel solution. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 78 ° C. for 60 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid E was obtained in the same manner as in Production Example A.

Production Example F
Using the same container and raw material as in Production Example A, 93 L of water and 0.6 L of sodium silicate aqueous solution were added and heated to 65 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 65 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 540 ml / min and sulfuric acid (18 mol / L) at a flow rate of 24 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, the reaction solution began to become cloudy, and the viscosity increased to a gel solution at 50 minutes. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 65 ° C. for 60 minutes. The silica concentration in the resulting solution was 55 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid F was obtained in the same manner as in Production Example A.

Production example G
Using the same container and raw material as in Production Example A, 86 L of water and 0.5 L of an aqueous sodium silicate solution were added and heated to 96 ° C. The concentration of Na ₂ O in the obtained solution was 0.005 mol / L.
While maintaining the temperature of this solution at 96 ° C., the same aqueous sodium silicate solution as described above was simultaneously added dropwise at a flow rate of 615 ml / min and sulfuric acid (18 mol / L) at a flow rate of 27 ml / min. While adjusting the flow rate, the neutralization reaction was performed while maintaining the Na ₂ O concentration in the reaction solution in the range of 0.00 to 0.01 mol / L. From the middle of the reaction, the reaction solution started to become cloudy, and the viscosity increased to a gel solution at 40 minutes. Further addition was continued and the reaction was stopped in 90 minutes. After stopping the reaction, the reaction solution temperature was maintained at 96 ° C. for 30 minutes. The silica concentration in the resulting solution was 62 g / L. Subsequently, sulfuric acid having the above-mentioned concentration was added until the pH of the solution reached 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid G was obtained in the same manner as in Production Example A.
In addition, in order to compare with the hydrous silicic acid (structural silica) AG obtained by the said manufacture example, the nip seal AQ made from Tosoh Silica which is a commercially available hydrous silicic acid (silica), and ULTRASIL made from Degussa The acoustic particle size distribution diameter, CTAB, heating loss and ignition loss of VN2 are shown in Table 1 below.
Also shown hydrated silica A~G obtained in the above Production Example 2, a relationship between commercial products two CTAB and acoustic particle size distribution diameter A _ac graphically.

Referring to FIG. 2, the hydrous silicic acid obtained in each production example has an A _ac above the straight line of Y (A _ac ) = − 0.76 × (CTAB) +274, and the above formula (II) is On the other hand, it can be seen that two types of commercially available hydrous silicic acid have small _Aac . Further, from Table 1 above, the hydrous silicic acids A to G of the respective production examples satisfy the above formula (V) in the difference between the loss on ignition and the loss on heating.

<Production example of carbon black>
Carbon black was manufactured using the carbon black manufacturing furnace 1 shown in FIG. Here, as the multistage cooling medium introducing means 12, a three-stage rapid cooling comprising a first rapid refrigerant introducing means 12-X, a second rapid refrigerant introducing means 12-Y, and a final rapid refrigerant introducing means 12-Z. Media introduction means were used. Moreover, in order to monitor the temperature in a manufacturing furnace, the said manufacturing furnace provided with the structure which can insert a thermocouple in an arbitrary several places in a furnace was used. In the carbon black production furnace, A heavy oil having a specific gravity of 0.8622 (15 ° C./4° C.) was used as the fuel, and heavy oil having the properties shown in Table 2 was used as the raw material oil. Further, carbon blacks A to C having the physical properties shown below were produced according to the operating conditions of the carbon black production furnace shown in Table 3.

About the obtained carbon black, dibutyl phthalate (DBP) absorption amount according to ASTM D2414-88 (JIS K6217-97), nitrogen adsorption specific surface area (N ₂ SA) according to ASTM D3037-88, ASTM The specific coloring power (TINT) was measured according to D3265-88, and the toluene coloring transmittance was measured according to JIS K6218-97.

(Examples 1-8, Comparative Examples 1-7)
Next, rubber components such as the above modified polybutadiene rubber and partially deproteinized natural rubber, hydrous silicic acid A, B, C, F, G obtained in the above production example, and carbon black A obtained in the above production example A rubber composition having the formulation shown in Tables 4 and 5 below was prepared according to a conventional method using ~ C, and the rubber composition was applied to a tread rubber. A heavy load tire of size 11R22.5 was prepared according to a conventional method. A prototype was manufactured, and rolling resistance, abrasion resistance, tear resistance and workability were evaluated by the following methods. These results are shown in Tables 4 and 5 below.

(1) Rolling resistance With respect to the test tire, the rolling resistance at 80 km / h was measured under a normal load and an internal pressure, and the rolling resistance of Comparative Example 1 was indicated as an index. It shows that rolling resistance is so small that an index value is small.

(2) Wear resistance The amount of wear after the test tire was mounted on the drive shaft of the truck and traveled 100,000 km was measured, and the index was displayed with the reciprocal of the amount of wear in Comparative Example 1 being 100. The larger the index value, the less the wear amount.
Shows excellent wear resistance.

(3) Tear resistance The total length of the tear after the test tire was mounted on the drive shaft of the truck and traveled 100,000 km was measured, and the reciprocal number of the total tear length of Comparative Example 1 was displayed as an index. A larger index value indicates fewer scratches and better tear resistance.
(4) Workability
According to JIS K6300-1994, Mooney viscosity (ML _{1 + 4} , 130 ° C.) was measured using L rotor under conditions of preheating 1 minute, rotor operating time 4 minutes, temperature 130 ° C. displayed. It shows that workability is so bad that this value is large.

* 1 to * 7 in Tables 4 and 5 are as follows.
* 1 RSS # 3.
* 2 Modified polybutadiene obtained by the above production example.
* 3 NIPSEAL AQ.
* 4 Shin-Etsu Chemical Co., Ltd., ABC-856.
* 5 BMH (naphthoic acid hydrazide) manufactured by Otsuka Chemical Co., Ltd.
* 6 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine.
* 7 N-cyclohexyl-2-benzothiazolylsulfenamide.

  As is clear from the results of Tables 4 and 5, the rubber component composed of natural rubber and modified conjugated diene polymer is blended with carbon black with a small amount of tar existing on the surface and structural hydrous silicic acid. The tires of Examples 1 to 8 that are within the scope of the present invention using the rubber composition are compared with Comparative Examples 1 to 7 that are outside the scope of the present invention, rolling resistance, wear resistance, tear resistance and workability. It can be seen that is highly balanced.

DESCRIPTION OF SYMBOLS 1 Carbon black production furnace 10 Reaction chamber 11 Reaction continuation and cooling chamber 12 Multistage rapid refrigerant body introduction means 12-X First rapid refrigerant body introduction means 12-Y Second rapid refrigerant body introduction means 12-Z Last sudden refrigerant body introduction means

Claims (16)

The rubber component, precipitated silica, and dibutyl phthalate (DBP) absorption number of 40~180cm ³ / 100g, a nitrogen adsorption specific surface area _(N 2 SA) in 40 to 300 m ² / g, the ratio tinting strength (TINT) Is a rubber composition formed by blending carbon black having a toluene coloring transmittance of 90% or more at 50 to 150%,
The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) of the hydrated silicic acid and the mode value A _ac (nm) of the diameter of the primary aggregate obtained by acoustic particle size distribution measurement are expressed by the following formula (I ):
A _ac ≧ −0.76 × (CTAB) +274 (I)
While satisfying
The carbon black uses a reaction apparatus in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, generates high temperature combustion gas in the combustion gas generation zone, and then feeds the raw material in the reaction zone To form a reaction gas stream containing carbon black, and then quenching the reaction gas stream by a multistage rapid refrigerant introduction means in the reaction stop zone to terminate the reaction, The toluene coloring permeability in the multistage rapid refrigerant introduction means is represented by the following formulas (II) and (III):
10 <X <40 (II)
90 <Z <100 (III)
[In the formula, X is the toluene coloring permeability (%) of carbon black after introduction of the first quenching medium from the raw material introduction position, and Z is the toluene coloring permeability (%) of carbon black after the last quenching medium introduction. It is a rubber composition characterized by satisfying the relationship of In carbon black, the relationship between the nitrogen adsorption specific surface area and the toluene coloring permeability is represented by the following formula (IV):
0.0283 × A × (100−B) ≦ 40 (IV)
^2. The rubber composition according to claim 1, wherein the rubber composition is a carbon black satisfying [wherein A is a nitrogen adsorption specific surface area (m ² / g) and B is a toluene color permeability (%)). . The hydrous silicic acid has an ignition loss (mass loss% when heated at 750 ° C. for 3 hours) and a heat loss (mass loss% when heated at 105 ° C. for 2 hours).
(Loss on ignition)-(Lose on heating) ≤ 3 (V)
The rubber composition according to claim 1, wherein:   The rubber composition according to claim 1 or 3, wherein the hydrous silicic acid has a mode of the diameter of the primary aggregate obtained by acoustic particle size distribution measurement of 1 µm or less. The rubber composition according to claim 1, wherein the hydrous silicic acid has a CTAB of 50 to 250 m ² / g.   The rubber component is at least one rubber selected from natural rubber and / or diene synthetic rubber, and 10 to 150 parts by mass of hydrous silicic acid is blended with 100 parts by mass of the rubber component. The rubber composition in any one of 1-5.   The rubber composition according to any one of claims 1 to 6, wherein the silane coupling agent is blended in an amount of 1 to 20 mass% of the blending amount of the hydrous silicic acid. A compound in which the silane coupling agent is represented by the following general formula (VI):
_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ·· (VI)
[Wherein, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, m is an integer of 1 to 3, and a is 1 An integer of ˜9, b is an integer of 1 or more, and may have a distribution. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ],
Compound represented by the following general formula (VII):
A _m B _3-m Si— (CH ₂ ) _c —Y (VII)
[In the formula, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Y is a mercapto group, a vinyl group, an amino group, It is a glycidoxy group or an epoxy group, m is an integer of 1 to 3, and c is an integer of 0 to 9. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]
And a compound represented by the following general formula (VIII):
A _m B _3-m Si _-as (CH ₂ ) _a -S _b -Z (VIII)
[In the formula, A is C _n H _{2n + 1} O (n is an integer of 1 to 3) or a chlorine atom, B is an alkyl group having 1 to 3 carbon atoms, Z is a benzothiazolyl group, N, N-dimethylthio It is a carbamoyl group or a methacryloyl group, m is an integer of 1 to 3, a is an integer of a production example of natural rubber (PNR) subjected to partial deproteinization treatment, and b is an integer of 1 or more and has a distribution. Also good. However, when m is 1, two B may be the same or different, and when m is 2 or 3, two or three A may be the same or different. ]
The rubber composition according to claim 7, wherein the rubber composition is at least one selected from the group consisting of:   The rubber composition according to any one of claims 1 to 8, wherein a blending amount of the carbon black is 55 parts by mass or less with respect to 100 parts by mass of the rubber component.   2. The rubber composition according to claim 1, wherein the rubber component is at least one selected from natural rubber and a modified conjugated diene polymer having at least one nitrogen-containing functional group.   The rubber composition according to claim 10, wherein the nitrogen-containing functional group is a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, or pyridyl group. The nitrogen-containing functional group has the following formula (IV):

[Wherein, R ¹ is each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, or an aralkyl group], and the following formula (V):

[Wherein R ² represents an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group], and a cyclic amino group represented by a cyclic amino group The rubber composition according to claim 10, wherein the rubber composition is selected from the group consisting of groups.   The rubber composition according to claim 11, wherein the nitrogen-containing functional group is a hexamethyleneimino group.   The rubber composition according to claim 10 or 11, wherein the conjugated diene polymer is a polybutadiene rubber.   The natural rubber is obtained from a latex obtained by partially deproteinizing protein in natural rubber latex by a mechanical separation method, and the total nitrogen content of the natural rubber exceeds 0.1% by mass and 0.4% by mass The rubber composition according to claim 1, wherein:   A tire using the rubber composition according to claim 1 as a tread rubber.

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