JP2012102249A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition capable of sufficiently achieving both the rolling resistance and the wear resistance when being applied to a member for a tire such as a tread.SOLUTION: In the rubber composition, a hydrous silicic acid is blended in which a cetyltrimethylammonium bromide adsorption specific surface area (CTAB)(m/g) and an ink bottle-like pore index (IB) satisfy expression (I): IB≤-0.36×CTAB+86.8 (I).

Description

  The present invention relates to a rubber composition capable of sufficiently achieving both rolling resistance and wear resistance when applied to a tire member, and a pneumatic tire using the rubber composition.

  Generally, a pneumatic tire is required to have high performance that can satisfy a plurality of performances simultaneously. In particular, tire members such as treads are strongly desired to have both tire rolling resistance and wear resistance. However, since these are in a trade-off relationship, more trial and error have been performed than before. Yes.

  In rubber compositions applied to tire treads, hydrous silicic acid is used as one of the reinforcing fillers. Generally, when the compounding amount of the reinforcing filler is increased, the wear resistance of the tires is to some extent. Although it can be improved, the rolling resistance may decrease, and in some cases, the viscosity of the unvulcanized rubber may increase more than necessary, and the processability may deteriorate.

  Under such circumstances, a technique has been developed that improves the dispersibility of the hydrous silicic acid particles in the rubber component and improves the rolling resistance of the tire by using hydrous silicic acid in which the primary particles are enlarged. On the other hand, Patent Document 1, for example, pays attention to the fact that the use of hydrous silicic acid with primary particles having a large particle size can cause a decrease in storage elastic modulus, while maintaining good dispersibility, and storage elastic modulus. In order to improve the low heat build-up, a technique using hydrous silicic acid with controlled cohesive force is also disclosed.

JP 2007-138069 A

  However, when using hydrous silicic acid with larger primary particles, although the rolling resistance of the tire can be improved to some extent, not only the storage elastic modulus may be lowered as described above, but also the wear resistance of the tire. May decrease. Moreover, even if it is a case where the hydrous silicic acid whose cohesion force etc. were controlled instead of this hydrous silicic acid is used from a viewpoint of aiming at coexistence with the rolling resistance and abrasion resistance of a tire. There is still room for improvement.

  On the other hand, hydrous silicic acid particles generally have a large number of pores with openings on the outer surface, and these pores are involved in the adsorption of rubber molecular chains. Since it is presumed that it contributes to the improvement of rolling resistance and wear resistance, it is also desirable to define the pore shape of such hydrous silicic acid.

  Then, an object of this invention is to provide the rubber composition which can fully aim at coexistence with rolling resistance and abrasion resistance, when it applies to the member for tires like a tread.

  In order to solve the above-mentioned problems, the present inventor has found a rubber composition containing a hydrous silicic acid having specific physical properties that are also involved in the shape of pores having openings on the outer surface of the particles. It came to complete.

That is, the rubber composition of the present invention has an ink bottle-like pore index (IB) of
In a measurement using a mercury porosimeter based on the mercury intrusion method for hydrous silicic acid having pores having an opening on the outer surface having a diameter in the range of 1.2 × 10 ⁵ nm to 6 nm, the pressure is 1 to 32,000 PSI. The diameter (M1) (nm) of the opening showing the maximum value of the mercury intrusion when the pressure is raised to 32,000 PSI and the diameter of the opening showing the maximum value of the mercury discharge when the pressure is lowered to 32000 PSI to 1 PSI ( M2) (nm), the following formula (X);
IB = M2-M1 (X)
Which is the value found in
Cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) and the ink bottle-like pore index (IB) are represented by the following formula (I):
IB ≦ −0.36 × CTAB + 86.8 (I)
Hydrous silicic acid satisfying the above is blended with the rubber component.

The hydrated silicic acid preferably has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 50 to 250 m ² / g.
The rubber component may be a natural rubber and / or a diene synthetic rubber, and the hydrous silicic acid may be blended in an amount of 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component. Good.
A silane coupling agent may be further blended in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the hydrous silicic acid.

The silane coupling agent has the following formula (IV):
_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ··· (IV)
Wherein (IV), 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, a is an integer of 1 to 9, and b is an integer of 1 or more. However, when m is 1, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. A compound represented by the following formula (V);
A _m B _3-m Si— (CH ₂ ) _c —Y (V)
Wherein (V), 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, It is an amino group, 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, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. A compound represented by the following formula (VI);
_{A m B 3-m Si- (} CH 2) a -S b -Z ··· (VI)
Wherein (VI), 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 -A dimethylthiocarbamoyl 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, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. And a compound represented by the following formula (VII):
^{_{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 ··· (VII)
[In the formula (VII), R ¹ represents R ⁶ O—, R ⁶ C (═O) O—, R ⁶ R ⁷ C═NO—, R ⁶ R ⁷ NO—, R ⁶ R ⁷ N— and — (OSiR ⁶ R ⁷ ) _n (OSiR ⁵ R ⁶ R ⁷ ) and having 1 to 18 carbon atoms (provided that R ⁶ and R ⁷ are each independently an alkyl group, a cycloalkyl group, an alkenyl group) Selected from a group, a cycloalkenyl group and an aryl group, and having 1 to 18 carbon atoms and n being 0 to 10);
R ² is selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group;
R ³ is — [O (R ⁸ O) _m ] _0.5 — (where R ⁸ is selected from an alkylene group and a cycloalkylene group, has 1 to 18 carbon atoms, and m is 1 to 4). );
x, y and z satisfy the relationship x + y + 2z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1;
R ⁴ is selected from an alkylene group, a cycloalkylene group, a cycloalkylalkylene group, an alkenylene group, an arylene group, and an aralkylene group, and has 1 to 18 carbon atoms;
R ⁵ is selected from an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, and an aralkyl group, and has 1 to 18 carbon atoms. It is desirable that it is at least one selected from the group consisting of compounds represented by the formula:

Carbon black may be further blended in an amount of 80 parts by mass or less with respect to 100 parts by mass of the rubber, and the total amount of the hydrous silicic acid and the carbon black may be 120 parts by mass or less.
The pneumatic tire of the present invention is characterized in that the rubber composition is applied to a tire member.

  According to the rubber composition of the present invention, hydrous silicic acid having specific physical properties related to the shape of pores having openings on the outer surface of the particles is blended, so that it is excellent when used in a tire. It can have both rolling resistance and wear resistance. Therefore, a high-performance pneumatic tire can be realized by using such a rubber composition as a tire member.

FIG. 2 is a cross-sectional view (partially enlarged view) in the inner-center direction of hydrous silicic acid particles. It is a mercury intrusion discharge curve (schematic diagram) of hydrous silicate by measurement using a mercury porosimeter based on the mercury intrusion method. The vertical axis represents the differential mercury intrusion amount (−dV / d (log d)) in the mercury intrusion curve C, and the differential mercury discharge amount (−dV / d (log d)) in the mercury discharge curve D. V represents the mercury intrusion amount (cc) in the mercury intrusion curve C, and mercury discharge (cc) in the mercury discharge curve D, and d represents the diameter (nm) of the opening in the pores of the hydrous silicic acid. means. The horizontal axis indicates this d (nm).

Hereinafter, the present invention will be specifically described with reference to the drawings as necessary.
The rubber composition of the present invention has an ink bottle-like pore index (IB) of
In a measurement using a mercury porosimeter based on the mercury intrusion method for hydrous silicic acid having pores having an opening on the outer surface having a diameter in the range of 1.2 × 10 ⁵ nm to 6 nm, the pressure is 1 to 32,000 PSI. The diameter (M1) (nm) of the opening showing the maximum value of the mercury intrusion when the pressure is raised to 32,000 PSI and the diameter of the opening showing the maximum value of the mercury discharge when the pressure is lowered to 32000 PSI to 1 PSI ( M2) (nm), the following formula (X);
IB = M2-M1 (X)
Which is the value found in
Cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) and the ink bottle-like pore index (IB) are represented by the following formula (I):
IB ≦ −0.36 × CTAB + 86.8 (I)
Hydrous silicic acid satisfying the above is blended with the rubber component.

  As the rubber component of the rubber composition of the present invention, natural rubber or diene synthetic rubber can be used alone, or natural rubber and diene synthetic rubber can be used in combination. Examples of the diene synthetic rubber include polyisoprene rubber (IR), styrene / butadiene copolymer rubber (SBR), and polybutadiene rubber (BR). Of these, styrene / butadiene copolymer rubber (SBR) is preferable. These diene synthetic rubbers may be used alone or in a blend of two or more.

In the rubber composition of the present invention, an ink bottle-like pore index (IB) determined by a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) and a mercury porosimeter with respect to the rubber component is represented by the following formula ( I);
IB ≦ −0.36 × CTAB + 86.8 (I)
It contains hydrous silicic acid that satisfies

Here, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) means a value measured according to ASTM D3765-92. However, since ASTM D3765-92 is a method for measuring CTAB of carbon black, in this specification, cetyltrimethylammonium bromide (hereinafter referred to as the following) is used instead of IRB # 3 (83.0 m2 / g) which is a standard product. A standard solution (abbreviated as CE-TRAB) is prepared, and the aqueous silicate OT (sodium di-2-ethylhexylsulfosuccinate) solution is standardized, and the adsorption cross-sectional area per CE-TRAB molecule on the hydrated silicate surface. Is 0.35 nm ² and the specific surface area (m ² / g) calculated from the adsorption amount of CE-TRAB is taken as the value of CTAB. 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.

The ink bottle-like pore index (IB) is a mercury intrusion method for hydrous silicic acid having pores having an opening on the outer surface with a diameter in the range of 1.2 × 10 ⁵ nm to ⁶ nm. In the measurement using the mercury porosimeter based on the above, the diameter (M1) (nm) of the opening showing the maximum value of the mercury intrusion when the pressure is raised to 1 to 32,000 PSI, and the pressure is lowered to 32000 PSI to 1 PSI From the diameter (M2) (nm) of the opening showing the maximum value of mercury emission in the following formula (X);
IB = M2-M1 (X)
Means the value obtained by. Measurement using a mercury porosimeter based on the mercury intrusion method is simpler than the measurement using an electron microscope, which has been widely used to evaluate pore morphology, and is a useful method because it has superior quantitativeness. is there.

Generally, hydrous silicic acid particles have a large number of concave pores having openings on the outer surface thereof. FIG. 1 is a schematic view simulating the shape of these pores in the cross section in the inner center direction of the hydrous silicic acid particles. Pores exhibited a concave according nisin cross section in the particle are exhibited various shapes, and the pore diameter (inner diameter) R _a in the inner diameter M _a and particles of the opening in the outer surface of the particles of substantially the same If there is a pore A having a shape, that is, a substantially cylindrical shape in a cross section in the inner center direction of the particle, the diameter M _b of the opening on the outer surface of the particle is narrower than the pore diameter (inner diameter) R _b inside the particle. There are also pores B that have a shape, that is, an ink bottle shape in the cross section in the inner center direction of the particles. However, if the pore B is in the shape of an ink bottle in the cross section in the inner-center direction of the particle, the rubber molecule chain is less likely to enter from the outer surface of the particle to the inside. The chains cannot be sufficiently adsorbed, rolling resistance may be lowered, and reinforcing properties may be insufficient, and it may be difficult to improve wear resistance. Therefore, if the number of pores B exhibiting such an ink bottle shape is reduced and the number of pores A exhibiting a substantially cylindrical shape in the cross section in the inner center direction of the particle is increased, the penetration of rubber molecular chains can be efficiently promoted. It is possible to contribute to the improvement of the wear resistance by exhibiting sufficient reinforcement without reducing the rolling resistance.

  From the above viewpoint, in the present invention, the water-containing silicic acid to be blended with the rubber component defines the ink bottle-shaped pore index (IB) in order to reduce the number of pores B exhibiting an ink bottle shape in the cross section in the inner center direction of the particles. To do. As described above, when the pressure is increased in the measurement using the mercury porosimeter based on the mercury intrusion method, the substantially cylindrical pore A has an opening on the outer surface, so the mercury inside the pore. However, since the opening on the outer surface of the pore B having an ink bottle shape is closed, it is difficult for mercury to be injected into the pore. On the other hand, when the pressure is lowered, for the same reason, mercury is easily discharged from the inside of the pore to the outside of the pore, but the pore B having an ink bottle shape is thin. Mercury is hardly discharged from the inside of the pore to the outside of the pore.

  Therefore, as shown in FIG. 2, in the measurement using the mercury porosimeter based on the mercury intrusion method, hysteresis occurs in the mercury intrusion curve CD. That is, mercury is gradually injected into the pore A having a substantially cylindrical shape under a relatively low pressure, but when reaching a certain pressure, the pore having the shape of an ink bottle that has been difficult for mercury to invade until then. Mercury is also injected into pores other than those having a substantially cylindrical shape, including B, and the amount of intrusion increases rapidly, and the vertical axis indicates the differential mercury intrusion amount (−dV / d (log d)). When the horizontal axis is the diameter M (nm) of the opening in the pores of hydrous silicic acid, a press-fitting curve C is drawn. On the other hand, if the pressure is lowered after the pressure has been sufficiently increased, mercury remains difficult to be discharged at a relatively high pressure, but when it reaches a certain pressure, it is pressed into the pores. Mercury was discharged to the outside of the pores at once, and the discharge amount increased rapidly, the vertical axis was the differential mercury discharge amount (-dV / d (log d)), and the horizontal axis was the opening in the pores of hydrous silicic acid. The discharge curve D is drawn when the diameter is M (nm). Mercury once press-fitted into the pores tends to be difficult to be discharged out of the pores when the pressure is lowered, so that when the pressure is lowered, the mercury is larger than the position of the diameter (M1) indicating an increase in the amount of press-in when the pressure is raised. An increase in the discharge amount is observed at the position of the diameter (M2) showing the value, and the difference between these diameters (M2−M1) corresponds to IB in FIG. In particular, in the pore B having an ink bottle shape, the tendency that the injected mercury is difficult to be discharged is remarkable, and mercury is pressed into the pore B when the pressure is increased, but the mercury is outside the pore B when the pressure is decreased. Is hardly discharged.

  Employing such a measurement method, utilizing the mercury intrusion curve CD drawn due to the nature of the pores, the pressure is measured in the measurement using the mercury porosimeter based on the mercury intrusion method according to the above formula (X). The diameter (M1) (nm) of the opening that shows the maximum value of mercury intrusion when raised to 1-32000 PSI and the opening that shows the maximum value of mercury discharge when the pressure is lowered to 32000 PSI to 1 PSI When the difference IB from the diameter (M2) (nm) of the ink is obtained, such a value apparently shows a difference between these diameters (length: nm), but is substantially in the form of an ink bottle present in the hydrous silicic acid. It means the pore index indicating the abundance ratio of the pores B exhibiting. In other words, the smaller the proportion of the pores B having a sufficiently narrow opening that occupy the ink bottle shape, the closer the mercury intrusion amount and the mercury discharge amount are to the same amount, and the opening showing the maximum value of the mercury intrusion amount. The difference between the diameter (M1) of the portion and the diameter (M2) of the opening showing the maximum value of the mercury discharge amount is shortened, and the IB value is reduced. On the other hand, the larger the proportion of the ink bottle-shaped pores B, the smaller the mercury discharge amount than the mercury intrusion amount. The maximum diameter of the mercury intrusion amount (M1) and the mercury discharge amount The difference with the diameter (M2) of the opening showing the maximum value increases, and the IB value increases.

Such an IB has a property that can vary depending on the value of the CTAB, and the IB value tends to decrease as the CTAB increases. Accordingly, the hydrous silicic acid used in the present application is represented by the following formula (I):
IB ≦ −0.36 × CTAB + 86.8 (I)
Meet. When IB and CTAB are hydrous silicic acids satisfying the above formula (I), the number of pores B having an ink bottle shape having a narrow opening is effectively reduced, and the presence of pores A having a substantially cylindrical shape is occupied Since the ratio increases, it is possible to sufficiently penetrate and adsorb rubber molecular chains, exhibit sufficient reinforcement, and improve wear resistance without reducing rolling resistance in the tire. Become.

The hydrated silicic acid preferably has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of preferably 50 to 250 m ² / g, more preferably 90 to 220 m ² / g. If the CTAB is less than 50 m ² / g, the wear resistance of the resulting tire may be significantly reduced. On the other hand, if it exceeds 250 m ² / g, the hydrous silicic acid cannot be dispersed well in the rubber component, the processability of the rubber may be remarkably lowered, and the physical properties such as wear resistance tend to be lowered.

  The amount of the hydrated silicic acid is preferably 10 to 150 parts by mass, more preferably 30 to 100 parts by mass with respect to 100 parts by mass of the rubber component. If the amount of hydrous silicic acid is less than 10 parts by mass, the low heat build-up of the rubber composition may be impaired, and if it exceeds 150 parts by mass, the processability of the rubber is reduced and the resulting tire has wear resistance. There is also a risk of reducing the nature.

  The rubber composition of the present invention is further compounded in an amount of 1 to 20 parts by weight, preferably 3 to 16 parts by weight, more preferably 5 to 12 parts by weight with respect to 100 parts by weight of the above-mentioned hydrous silicic acid. It is desirable to be made. By blending the silane coupling agent in an amount of 1 part by mass or more with respect to 100 parts by mass of hydrous silicic acid, the effect of hydrous silicic acid blending is further improved, such as low exothermic property and storage modulus of the rubber composition While the physical properties can be further improved, even if blended in an amount exceeding 20 parts by mass, the low heat build-up, storage elastic modulus and the like cannot be further improved, and the cost may increase.

As said silane coupling agent, following formula (IV);
_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ··· (IV)
[In the formula (IV), A, B, m, a, and b are as defined above], a compound represented by the following formula (V);
A _m B _3-m Si— (CH ₂ ) _c —Y (V)
[In the formula (V), A, B, Y, m, and c are as defined above], a compound represented by the following formula (VI);
_{A m B 3-m Si- (} CH 2) a -S b -Z ··· (VI)
[In the formula (VI), A, B, Z, m, a, and b are as defined above], and the following formula (VII);
^{_{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 ··· (VII)
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , x, y and z are as defined above] are preferred, and these silane coupling agents are 1 type may be used independently and 2 or more types may be mixed and used for it.

  The compounds represented by the above formula (IV) include 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 and the like can be mentioned.

  Examples of the compound represented by the formula (V) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3 -Aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like. Examples of these commercially available products include trade name “VP Si363” manufactured by Evonik Degussa.

  Further, the compound represented by the above formula (VI) includes 3-trimethoxysilylpropyl-N, N-dimethylcarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-trimethoxysilylpropyl. And methacryloyl monosulfide.

In the compound represented by the formula (VII), in the formula (VII), in R ² , R ⁵ , R ⁶ and R ⁷ , the alkyl group may be linear or branched. Examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The alkenyl group may be linear or branched, and examples of the alkenyl group include a vinyl group, an allyl group, and a methanyl group. Furthermore, examples of the cycloalkyl group include a cyclohexyl group and an ethylcyclohexyl group, examples of the cycloalkenyl group include a cyclohexenyl group and an ethylcyclohexenyl group, and examples of the aryl group include a phenyl group and a tolyl group. Furthermore, in R ⁵ , examples of the aralkyl group include a phenethyl group.

In the above formula (VII), in R ⁴ and R ⁸ , the alkylene group may be linear or branched, and examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, and a propylene group. Examples of the cycloalkylene group include a cyclohexylene group. Furthermore, in R ⁴ , the alkenylene group may be linear or branched, and examples of the alkenylene group include a vinylene group and a propenylene group. Examples of the cycloalkylalkylene group include a cyclohexylmethylene group, examples of the arylene group include a phenylene group, and examples of the aralkylene group include a xylylene group.

In the above formula (VII), in R ³ , the — [O (R ⁸ O) _m ] _0.5 — group is a 1,2-ethanedioxy group, 1,3-propanedioxy group, or 1,4-butanedioxy group. Group, 1,5-pentanedioxy group, 1,6-hexanedioxy group and the like.
The compound represented by the above formula (VII) can be synthesized in the same manner as the method described in JP-T-2001-505225. Also, the product name “NXT” (formula (Made by Momentive Performance Materials) R ¹ = C ₂ H ₅ O of _{^{VII), R 4 = C 3}} H 6, R 5 = C 7 H 15, x = 3, y = 0, z = 0: 3- octanoylthio - propyltriethoxysilane), etc. It is also possible to use commercially available products.
Among them, among the compounds represented by the above formula (IV), (V), (VI) or (VII), the compound represented by the above formula (V) or the compound represented by the above formula (VII) Is preferred.

  In addition, the silane coupling agent has a cyclic structure containing a nitrogen atom (N) and a silicic atom (Si) in the molecule and one or more sulfur atoms (S), and has a small steric hindrance. An organosilicon compound having a site in which one or more groups are bonded to a silicon atom (Si) can be used. This organosilicon compound has a cyclic structure containing a nitrogen atom (N) and a silicon atom (Si), and the cyclic structure is stable even when it contains a silicon-oxygen bond (Si-O). is there. Therefore, the silicon-oxygen bond (Si-O) is not hydrolyzed to generate an alcohol component, and the volatile organic compound (VOC) gas in use can be reduced.

  Since the organosilicon compound contains a nitrogen-containing functional group such as an amino group, an imino group, a substituted amino group, or a substituted imino group that has a high affinity with the surface of an inorganic filler such as silica, a lone pair of nitrogen atoms However, it can participate in the reaction between the organic silicic compound and the inorganic filler, and the coupling reaction rate is fast. However, when the cyclic structure containing a nitrogen atom (N) and a silicon atom (Si) is a bicyclic structure, since the steric hindrance around the silicon atom (Si) is large, the reactivity with the inorganic filler is low, Coupling efficiency is greatly reduced. Since the organosilicon compound used in the present invention has a site where one or more groups having small steric hindrance are bonded to a silicon atom, the organosilicon compound has high reactivity with an inorganic filler such as silica. Therefore, in place of the conventional silane coupling agent, by adding this organosilicon compound to the inorganic filler-containing rubber composition, the coupling efficiency is improved, and as a result, the hysteresis loss of the rubber composition is greatly increased. It is possible to greatly improve the wear resistance while lowering. In addition, since the organosilicon compound of the present invention has high addition efficiency, a high effect can be obtained even in a small amount, and it contributes to reduction of the blending cost.

The group having a small steric hindrance is preferably a hydrogen atom (—H), a methyl group (—CH ₃ ), a hydroxyl group (—OH), or the like. When a hydrogen atom, a methyl group or a hydroxyl group is bonded to a silicon atom (Si), the reactivity between the organosilicon compound and the inorganic filler is particularly high, and the coupling efficiency can be greatly improved. The organosilicon compound preferably has 1 to 6 silicon-oxygen bonds (Si-O). This is because when the organosilicon compound has 1 to 6 silicon-oxygen bonds (Si—O), the reactivity with an inorganic filler such as silica is high, and the coupling efficiency is further improved.

  Specifically, the organic silicon compound used in the present invention is preferably a compound represented by the following general formula (XI). These organosilicon compounds may be used alone or in combination of two or more.

［式中、Ａは硫黄原子（Ｓ）を含み且つゴム成分と反応する基であり、Ｒ^１及びＲ^２はそれぞれ独立して−Ｍ−Ｃ_ｌＨ_２ｌ−（ここで、Ｍは−Ｏ−又は−ＣＨ_２−で、ｌは０〜１０である）で表わされ、但し、Ｒ^１及びＲ^２の一つ以上はＭが−Ｏ−であり、Ｒ^３は水素原子、メチル基又はヒドロキシル基、Ｒ^４は−ＣｎＨ_２ｎ＋１であり、ｎは０〜２０である。］

[Wherein, A is a group containing a sulfur atom (S) and reacting with the rubber component, and R ¹ and R ² are each independently -M-C ₁ H ₂ ^1- (where M is -O- or -CH ₂ -, l is represented by a is) 0-10, provided that one or more of ^{R 1} and ^{R 2} is M is -O-, ^{R 3} is a hydrogen atom, a methyl group or a hydroxyl The group R ⁴ is —CnH _{2n + 1} and n is 0-20. ]

In general formula (XI), A is a group containing a sulfur atom (S) and reacting with the rubber component. In the organosilicon compound represented by the formula (XI), since the cyclic portion reacts with an inorganic filler such as silica, the rubber component and the inorganic filler The coupling ability is as follows. Here, the group containing a sulfur atom (S) and reacting with the rubber component is a polysulfide group, a thioester group, a thiol group, a dithiocarbonate group, a dithioacetal group, a hemithioacetal group, a vinylthio group, an α-thiocarbonyl group, It preferably contains at least one selected from the group consisting of β-thiocarbonyl group, S—CO—CH ₂ —O moiety, S—CO—CO moiety (thiodiketone group), and S—CH ₂ —Si moiety, It is particularly preferable that at least one of a polysulfide group and a thioester group is included.

In General Formula (XI), R ¹ and R ² are each independently represented by —M—C ₁ H _2l —, where M is —O— or —CH ₂ , and l is 0 to 10 is there. However, in one or more of R ¹ and R ² , M is —O—. -C _l H _2l -is a single bond or an alkylene group having 1 to 10 carbon atoms, since l is 0 to 10, wherein the alkylene group having 1 to 10 carbon atoms is a methylene group or an ethylene group , Trimethylene group, propylene group and the like, and the alkylene group may be linear or branched.

In general formula (XI), R ³ is a hydrogen atom, a methyl group or a hydroxyl group. Since R ³ has small steric hindrance, it greatly contributes to the improvement of the coupling reaction between the rubber component and the inorganic filler.

- In general formula (XI), ^{R 4} is _-C n _{H 2n + 1,} n is 0 to 20.
-C _n H _{2n + 1} is, for n is 0 to 20, hydrogen or an alkyl group having 1 to 20 carbon atoms. Here, as the alkyl group having 1 to 20 carbon atoms, methyl group, ethyl group, propyl group, butyl group pentyl group, hexyl group, octyl group, decyl group, undecyl grave, dodecyl group, nonadecyl group, eicosyl group, etc. The alkyl group may be linear or branched.

［式（ＸＩＩ）中のＲ^１、Ｒ^２、Ｒ^３及びＲ^４は上記と同義であり、式（ＸＩＩ）及び式（ＸＩＩＩ）中のＲ⁶は下記一般式（ＸＶ）又は（ＸＶＩ） A in the general formula (XI) is preferably represented by the following general formula (XII), (XIII) or (XIV).

[R ¹ , R ² , R ³ and R ⁴ in Formula (XII) are as defined above, and R ⁶ in Formula (XII) and Formula (XIII) is the following General Formula (XV) or (XVI)

（式中、Ｍ及びｌは上記と同義、ｍは０〜１０であり、Ｘ及びＹはそれぞれ独立して−Ｏ、−ＮＲ^４−又は−ＣＨ₂−で、Ｒ^１２は−ＯＲ^４、−ＮＲ^４Ｒ^６又は−Ｒ^４で、Ｒ^１３は−ＮＲ^４−、−ＮＲ^４−ＮＲ^４−又は−Ｎ＝Ｎ−であり、但し、Ｒ^４は上記と同義、Ｒ^５はＣ_ｑＨ_２ｑ＋１で、ｑは１〜１０である）或いは−Ｍ−Ｃ_ｌＨ_２ｌ−（Ｍ及び１は上記と同義である）で表わされ、

Wherein M and l are as defined above, m is 0 to 10, X and Y are each independently —O, —NR ⁴ — or —CH ₂ —, R ¹² is —OR ⁴ , — In NR ⁴ R ⁶ or —R ⁴ , R ¹³ is —NR ⁴ —, —NR ⁴ —NR ⁴ — or —N═N—, wherein R ⁴ is as defined above, and R ⁵ is C _q H _{2q + 1.} in, q is 1 to 10 at a) or _{-M-C l H 2l} - is represented by (M and 1 have the same meanings as mentioned above),

（式中、Ｍ、Ｘ、Ｙ、Ｒ^１３、ｌ及びｍは上記と同義、Ｒ^１４は−ＮＲ^４Ｒ^５、−ＮＲ^４ＮＲ^４Ｒ^６、−Ｎ＝ＮＲ^４である）或いは−Ｃ_ｌＨ_２ｌ−Ｒ^１５（Ｒ^１５は−ＮＲ^４Ｒ^５、−ＮＲ^４−ＮＲ^４Ｒ^５、−Ｎ=ＮＲ⁴又は−Ｍ−Ｃ_ｍＨ_2ｍ+1或いは炭素６〜２０の芳香族炭化水素基であり、但し、Ｒ^４、Ｒ^５、Ｍ、ｌ及びｍは上記と同義である）で表わされ、
式（ＸＩＩ）及び（ＸＩＩＩ）中のｘは１〜１０であり、
式（ＸＩＶ）中のＲ^８、Ｒ^９及びＲ^１０はそれぞれ独立して−Ｍ−Ｃ_ｐＨ_2ｐ−（ここで、Ｍは−Ｏ−又は−ＣＨ_２であり、ｐは０〜２０である）、Ｒ¹¹はＨ，ＯＨ又はメチル基である］
で表わされることが好ましい。式（ＸＩＩ）及び式（ＸＩＩＩ）中のｘは１〜１０であるが、好ましくは２〜４である。 R ⁷ in formula (XIII) is the following general formula (XVII) or (XVIII),

(Wherein, M, X, Y, R ¹³ , l and m are as defined above, R ¹⁴ is —NR ⁴ R ⁵ , —NR ⁴ NR ⁴ R ⁶ , —N = NR ⁴ ) or —C _l H _2l -R ¹⁵ (R ¹⁵ is -NR ⁴ R ⁵ , -NR ⁴ -NR ⁴ R ⁵ , -N = NR ⁴ or -M-C _m H _{2m + 1} or an aromatic hydrocarbon group having 6 to 20 carbon atoms. Wherein R ⁴ , R ⁵ , M, l and m are as defined above),
X in the formulas (XII) and (XIII) is 1 to 10,
^R 8, ^{R 9} and ^{R 10} in formula (XIV) are each independently _-M-C p H _2p - (wherein, M is -O- or -CH _2, p is 0 to 20 R ¹¹ is H, OH or a methyl group]
It is preferable to be represented by X in the formulas (XII) and (XIII) is 1 to 10, preferably 2 to 4.

In the above formulas (XV) and (XVI), M is —O— or —CH ₂ —, and l and m are 0 to 10. In the formula (V), X and Y are each independently —O—, —NR ⁴ — or —CH ₂ —, and R ¹² is —OR ⁴ , —NR ⁴ R ⁵ or —R ^4. Where R ⁴ is —C _n H _{2n + 1} and R ⁶ is C _q H _{2q + 1} . Further, in the above formula (XVI), R ¹³ is —NR ⁴ —, —NR ⁴ —NR ⁴ —, or —N═N—, wherein R ⁴ is —C _n H _{2n + 1} .
The -C _n H _{2n + 1,} are as described _above, -C _{m H 2m} -, since m is 0-10, a single bond or an alkylene group having a carbon teaching 1-10. Here, examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a propylene group, and the like, and the alkylene group may have a straight mirror shape or a branched shape.
Further, -C _q H _{2q + 1,} since q is 0, is hydrogen or an alkyl group having 1 to 10 carbon atoms. Here, examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group. The chain may be branched or branched.

R ⁷ in the above formula (XIII) is represented by the above general formula (XVII) or (XVIII), or —C ₁ H _2l —R ¹⁶ , particularly represented by —C ₁ H _{2l + 1} Is preferred. However, M, X, Y, R ¹² , R ¹⁴ , l and m are as defined above. Here, R ¹⁵ is —NR ⁴ R ⁵ , —NR ⁴ N ⁴ R ⁵ , —N═NR ⁴ or —M—C _m H _{2m + 1,} or an aromatic hydrocarbon group having 6 to 20 carbon atoms, R ⁴ , R ⁵ , M, l and m are as defined above.
Incidentally, _-C l H _{2l -} For are as described above, _also, -C _{m H 2m + 1 is,} m is hydrogen or an alkyl group having 1 to 10 carbon atoms because it is 0-10, carbon atoms 1 -10 alkyl groups include a methyl group, an ethyl group, a provir group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group. The alkyl group may be linear or branched. But you can. Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, cumenyl group, naphthylene group and tolylene group, and aralkyl groups such as benzyl group and phenethyl group.

Further, _-C in the formula _{(XIV) p H 2p + 1} - , since p is 0 to 20, a single bond or an alkylene group with 1 to 20 carbon atoms. Here, examples of the alkylene group having 1 to 20 carbon atoms include methylene group, ethylene group, trimethylene group, propylene group, decamethylene cold, eicosamethylene group and the like, and the alkylene group may be linear or branched. .

In the compound of the above formula (XI), M is preferably —O— (oxygen). In this case, M is -CH 2 _- are highly reactive with inorganic Takashiko such as silica as compared to compounds wherein.

In Formula (XI), R ¹ and R ² are preferably each independently represented by —O—C ₁ H _2l —, R ³ is a hydrogen atom, a methyl group or a hydroxyl group, and R ⁶ Is preferably represented by —O—C ₁ H _2l —, and R ⁷ is a linear or branched alkyl group represented by —O—C ₁ H _2l —, or a group having 6 to 20 carbon atoms. An aromatic hydrocarbon group is preferred.

The compound represented by the organosilicon compound, for example, (C ₁ H _{21 + 1} O) ₂ R ⁹ Si-A [wherein l, R ³ and A are as defined above], N-methyldiethanolamine, N - an amine compound such as ethyl diethanolamine was added, further p- toluenesulfonic acid as a catalyst, and an acid such as hydrochloric acid, was added titanium alcoholates Sid such as titanium tetra-n- butoxide and heated, two C _{l H} 2l _{+ 1} O It can be synthesized by substituting — with a divalent group represented by —R ¹ —NR ⁴ —R ² —.

  The organosilicon compound has a cyclic structure including a nitrogen atom (N) and a silicon atom (Si), and the cyclic structure is stable even when it includes a silicon-oxygen bond (Si-O). is there. Therefore, the silicon-oxygen bond (Si-O) is not hydrolyzed to generate an alcohol component, which is effective in that the volatile organic compound (VOC) gas in use can be reduced.

  The rubber composition of the present invention may further contain carbon black as a reinforcing filler, and the amount of the carbon black is 80 parts by mass or less, preferably 60 parts by mass with respect to 100 parts by mass of the rubber component. It is desirable that the amount be no more than parts. If the blending amount of carbon black exceeds 80 parts by mass with respect to 100 parts by mass of the rubber component, the low heat buildup of the rubber composition may be deteriorated. In this case, the total amount of the carbon black and the hydrous silicic acid is desirably 120 parts by mass or less, preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component. By making the total blending amount of carbon black and hydrous silicic acid 120 parts by mass or less with respect to 100 parts by mass of the rubber component, low heat build-up of the rubber composition is realized and rolling resistance is sufficiently improved. Can do.

  In the rubber composition of the present invention, an additive compounded in a normal rubber composition can be blended to such an extent that the effects of the present invention are not impaired. For example, an anti-aging agent or additive commonly used in the rubber industry is added. Additives such as a sulfur accelerator, sulfur, zinc oxide, stearic acid, and an ozone deterioration preventing agent can be appropriately blended. The rubber composition of the present invention is obtained by kneading using an open kneader such as a roll or a closed kneader such as a Banbury mixer, and vulcanized after molding to produce various rubber products. It is applicable to.

  The pneumatic tire of the present invention is characterized in that the rubber composition is applied to any of the tire members. Among such tire members, a tread is particularly preferable. In a tire using the rubber composition as a tread, the rubber composition has low rolling resistance and excellent wear resistance. In addition, as gas with which the tire of this invention is filled, normal or air which changed oxygen partial pressure, or inert gas, such as nitrogen, is mentioned.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
The physical properties of hydrous silicic acid were evaluated by the following methods.

<Measurement of ink bottle-like pore index (IB)>
Using the mercury porosimeter POREMASTER-33 (manufactured by Quantachrome), as described above, based on the mercury intrusion method, the pressure was first increased to 1 to 32,000 PSI, and the diameter of the opening 1.2 × 10 6 on the outer surface of the hydrous silicic acid ^The amount of mercury intrusion was measured for pores of ⁵ nm to ⁶ nm, and the diameter (M1) located at the peak of the amount of indentation was determined as shown in FIG. Next, the pressure was lowered to 32000 PSI to 1 PSI, and mercury was discharged from the pores. The diameter (M2) located at the peak of the discharge amount obtained from the discharge curve at this time was determined. IB was calculated from the values of M1 and M2 by the above formula (X).

<< Measurement of CTAB >>
This was carried out in accordance with the method described in ASTM D3765-92. At this time, as described above, a standard solution of cetyltrimethylammonium bromide (hereinafter abbreviated as CE-TRAB) was prepared without using IRB # 3 (83.0 m ² / g) which is a standard product of carbon black. Thus, the hydrated silicic acid OT (sodium di-2-ethylhexylsulfosuccinate) solution was standardized, and the adsorption cross-section per CE-TRAB molecule on the hydrous silicic acid surface was 0.35 nm ² to adsorb CE-TRAB. The specific surface area (m ² / g) was calculated from the amount.

[Production Example 1: Production of hydrous silicate A]
In a 180 liter jacketed stainless steel reaction vessel equipped with a stirrer, 65 liters of water and 1.25 liters of a sodium silicate aqueous solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed. Heated to ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 96 ° C., a sodium silicate aqueous solution similar to the above was simultaneously added dropwise at a flow rate of 750 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 33 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 0.005 to 0.035 mol / liter. The reaction solution started to become cloudy from the middle of the reaction, and the viscosity increased to a gel solution at 30 minutes. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 85 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 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. Subsequently, the wet cake was made into a slurry using an emulsifying device and dried with a spray dryer to obtain a wet method hydrous silicic acid A.

[Production Example 2: Production of hydrous silicate B]
In the same stainless steel reaction tank as in Production Example 1, 89 liters of water and 1.70 liters of an aqueous sodium silicate solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 75 ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 75 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 520 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 23 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 0.005 to 0.035 mol / liter. From the middle of the reaction, the reaction solution started to become cloudy, and the viscosity increased to a gel solution at 46 minutes. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 60 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 3, to obtain a silicic acid slurry. Thereafter, a wet method hydrous silicic acid B was obtained in the same manner as in Production Example 1.

[Production Example 3: Production of hydrous silicate C]
In the same stainless steel reactor as in Production Example 1, 65 liters of water and 1.25 liters of an aqueous sodium silicate solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 85 ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 85 ° C., an aqueous sodium silicate solution similar to the above was simultaneously added dropwise at a flow rate of 750 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 33 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 0.005 to 0.035 mol / liter. From the middle of the reaction, the reaction solution started to become cloudy, and the viscosity increased to a gel solution at 31 minutes. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 85 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 3, to obtain a silicic acid slurry. Thereafter, a wet method hydrous silicic acid C was obtained in the same manner as in Production Example 1.

[Production Example 4: Production of hydrous silicic acid D]
In the same stainless steel reaction vessel as in Production Example 1, 65 liters of water and 1.25 liters of a sodium silicate aqueous solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 80 ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 80 ° C., a sodium silicate aqueous solution similar to the above was simultaneously added dropwise at a flow rate of 750 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 33 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 0.005 to 0.035 mol / liter. From the middle of the reaction, the reaction solution started to become cloudy, and the viscosity increased to a gel solution at 31 minutes. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 85 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid D was obtained in the same manner as in Production Example 1.

[Production Example 5: Production of hydrous silicic acid E]
In the same stainless steel reaction tank as in Production Example 1, 89 liters of water and 1.70 liters of an aqueous sodium silicate solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 85 ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 85 ° C., a sodium silicate aqueous solution similar to the above was simultaneously added dropwise at a flow rate of 520 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 23 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 0.005 to 0.035 mol / liter. From the middle of the reaction, the reaction solution began to become cloudy and increased in viscosity at 45 minutes to become a gel-like solution. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 60 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid E was obtained in the same manner as in Production Example 1.

[Production Example 6: Production of hydrous silicic acid F]
In the same stainless steel reaction vessel as in Production Example 1, 89 liters of water and 1.70 liters of an aqueous sodium silicate solution (SiO ₂ 160 g / liter, SiO ₂ / Na ₂ O molar ratio 3.3) were placed and heated to 80 ° C. The concentration of Na ₂ O in the resulting solution was 0.015 mol / liter.

While maintaining the temperature of this solution at 80 ° C., the same sodium silicate aqueous solution as described above was simultaneously added dropwise at a flow rate of 520 ml / min and sulfuric acid (18 mol / liter) at a flow rate of 23 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 0.005 to 0.035 mol / liter. From the middle of the reaction, the reaction solution began to become cloudy and increased in viscosity at 45 minutes to become a gel-like solution. Further, the addition was continued and the reaction was stopped after 100 minutes. The silica concentration in the resulting solution was 60 g / liter. Subsequently, the same sulfuric acid as described above was added until the pH of the solution became 3, to obtain a silicic acid slurry. Thereafter, wet method hydrous silicic acid F was obtained in the same manner as in Production Example 1.

[Comparative Examples 1-4, Examples 1-6]
Tires having a size of 195 / 65R15, in which rubber compositions using the hydrous silicic acids shown in Tables 2 to 3 were prepared according to the conventional methods according to the formulation shown in Table 1, and further applied to tread rubbers. Were prototyped according to conventional methods, and wear resistance and rolling resistance were evaluated by the following methods. The results are shown in Tables 2-3.

[Comparative Example 5, Examples 7-9]
A rubber composition using the hydrous silicic acid shown in Table 5 according to the formulation shown in Table 4 was prepared according to a conventional method, and a tire having a size of 195 / 65R15 was applied to the tread rubber. A prototype was prepared according to the method, and the wear resistance and rolling resistance were evaluated by the following methods. The results are shown in Table 5.

《Abrasion resistance》
The remaining groove amount after running the test tire on the vehicle and running 20,000 km is measured. In Tables 2 and 3, the remaining groove amount in Comparative Example 1 is set to 100, and in Table 5, the remaining groove amount in Comparative Example 5 is measured. The index is shown as 100. It shows that it is excellent in abrasion resistance, so that an index value is large.

《Rolling resistance》
For the test tire, the rolling resistance at 80 km / h was measured with an indoor uniaxial rolling resistance measuring drum tester. In Tables 2 to 3, the rolling resistance of Comparative Example 1 was set to 100, and in Table 5 to Comparative Example 5 The rolling resistance was set to 100 and indicated as an index. It shows that rolling resistance is so small that an index value is large.

* 1: # 1500, manufactured by JSR
* 2: Registered trademark Seast KH (N339), manufactured by Tokai Carbon Co., Ltd. * 3: Hydrous silicic acid shown in Tables 2-3 * 4: NXT (registered trademark), manufactured by Momentive Performance Materials * 5: N- ( 1,3-Dimethylbutyl) -N'-phenyl-p-phenylenediamine, Nolac 6C, manufactured by Ouchi Shinsei Chemical Industry * 6: Diphenylguanidine, Noxeller D, manufactured by Ouchi Shinsei Chemical Industry * 7: Benzothiazyl disulfide, Noxeller DM-P, manufactured by Ouchi Shinsei Chemical Industry * 8: Nt-butyl-2-benzothiazylsulfenamide, Noxeller NS-P, manufactured by Ouchi Shinsei Chemical Industry

* 9: Nipsil AQ, manufactured by Tosoh Silica * 10: VN2, manufactured by Degussa * 11: Ultrasil7000GR, manufactured by Degussa * 12: TOKUSIL255G, manufactured by OSC

* 1: # 1500, manufactured by JSR * 2: Registered trademark Seast KH (N339), manufactured by Tokai Carbon Co., Ltd. * 3: Hydrous silicic acid shown in Table 5 * 13: Bis (3-triethoxysilylpropyl) tetrasulfide, Evonik・ Si69, manufactured by Degussa
* 5: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, Nolac 6C, manufactured by Ouchi Shinsei Chemical Industry * 6: Diphenylguanidine, Noxeller D, manufactured by Ouchi Shinsei Chemical Industry * 7 : Benzothiazyl disulfide, Noxeller DM-P, manufactured by Ouchi Shinsei Chemical Industry * 8: Nt-butyl-2-benzothiazylsulfenamide, Noxeller NS-P, manufactured by Ouchi Shinsei Chemical Industry

  * 9: Nipsil AQ, manufactured by Tosoh Silica

  According to the results of Tables 2 to 3 and 5, Examples 1 to 6 and 7 to 9 to which the rubber composition containing the hydrous silicic acid satisfying the above formula (I) was applied are compared with Comparative Examples 1 to 4 and 5. In comparison, it can be seen that excellent rolling resistance and wear resistance are exhibited in a well-balanced manner.

A: Fine pores having a substantially cylindrical shape B: Fine pores having an ink bottle shape M _a : Diameter of the opening of the pore A on the outer surface of the particle M _b : Diameter of the opening of the pore B on the outer surface of the particle R _a : pore diameter (inner diameter) of pore A inside the particle
R _b : pore diameter (inner diameter) of pore B inside the particle
C: Mercury intrusion curve D: Mercury discharge curve M1: Diameter of opening showing maximum value of mercury intrusion amount M2: Diameter of opening showing maximum value of mercury discharge amount IB: Ink bottle-like pore index

Claims (7)

Ink bottle-like pore index (IB)
In a measurement using a mercury porosimeter based on the mercury intrusion method for hydrous silicic acid having pores having an opening on the outer surface having a diameter in the range of 1.2 × 10 ⁵ nm to 6 nm, the pressure is 1 to 32,000 PSI. The diameter (M1) (nm) of the opening showing the maximum value of the mercury intrusion when the pressure is raised to 32,000 PSI and the diameter of the opening showing the maximum value of the mercury discharge when the pressure is lowered to 32000 PSI to 1 PSI ( M2) (nm), the following formula (X);
IB = M2-M1 (X)
Which is the value found in
Cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m ² / g) and the ink bottle-like pore index (IB) are represented by the following formula (I):
IB ≦ −0.36 × CTAB + 86.8 (I)
A rubber composition comprising water-containing silicic acid satisfying the above requirements in a rubber component. ^2. The rubber composition according to claim 1, wherein the hydrated silicic acid has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 50 to 250 m ² / g. The rubber component is composed of natural rubber and / or a diene synthetic rubber, and the hydrous silicic acid is blended in an amount of 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition according to 1 or 2.   The rubber composition according to any one of claims 1 to 3, further comprising a silane coupling agent in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the hydrous silicic acid. The silane coupling agent has the following formula (IV):
_{A m B 3-m Si- (} CH 2) a -S b - (CH 2) a -SiA m B 3-m ··· (IV)
Wherein (IV), 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, a is an integer of 1 to 9, and b is an integer of 1 or more. However, when m is 1, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. A compound represented by the following formula (V);
A _m B _3-m Si— (CH ₂ ) _c —Y (V)
Wherein (V), 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, It is an amino group, 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, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. A compound represented by the following formula (VI);
_{A m B 3-m Si- (} CH 2) a -S b -Z ··· (VI)
Wherein (VI), 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 -A dimethylthiocarbamoyl 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, B may be the same or different from each other, and when m is 2 or 3, A may be the same or different from each other. And a compound represented by the following formula (VII):
_{^{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 ··· (VII)
[In the formula (VII), R ¹ represents R ⁶ O—, R ⁶ C (═O) O—, R ⁶ R ⁷ C═NO—, R ⁶ R ⁷ NO—, R ⁶ R ⁷ N— and — (OSiR ⁶ R ⁷ ) _n (OSiR ⁵ R ⁶ R ⁷ ) and having 1 to 18 carbon atoms (provided that R ⁶ and R ⁷ are each independently an alkyl group, a cycloalkyl group, an alkenyl group) Selected from a group, a cycloalkenyl group and an aryl group, and having 1 to 18 carbon atoms and n being 0 to 10);
R ² is selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group;
R ³ is — [O (R ⁸ O) _m ] _0.5 — (where R ⁸ is selected from an alkylene group and a cycloalkylene group, has 1 to 18 carbon atoms, and m is 1 to 4). );
x, y and z satisfy the relationship x + y + 2z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1;
R ⁴ is selected from an alkylene group, a cycloalkylene group, a cycloalkylalkylene group, an alkenylene group, an arylene group, and an aralkylene group, and has 1 to 18 carbon atoms;
R ⁵ is selected from an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, and an aralkyl group, and has 1 to 18 carbon atoms. The rubber composition according to claim 4, wherein the rubber composition is at least one selected from the group consisting of compounds represented by the formula:   Carbon black is further compounded in an amount of 80 parts by mass or less with respect to 100 parts by mass of the rubber component, and the total compounding amount of the hydrous silicic acid and the carbon black is 120 parts by mass or less. The rubber composition according to claim 4 or 5.   A pneumatic tire, wherein the rubber composition according to claim 1 is applied to a tire member.

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