JP2010241970A - Rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition exhibiting a high hysteresis loss property and a circumferential directional high elastic modulus (E'), while maintaining its dynamic physical properties, and having a high grip property on being applied to a tire, and a tire using the same, and further, the rubber composition capable of improving the durability as the tire by an improved thermal conductivity, and the tire using the same. <P>SOLUTION: This rubber composition is provided by blending 0.1 to 80 pts.mass carbon fiber produced by a gas phase growth method, consisting of ≥1 carbon net layer having a cup form without having a bottom part as a filler and a 60 to 150 pts.mass filler other than the carbon fiber based on 100 pts.mass rubber, and the tire using the same is also provided. It is preferable that the filler other than the carbon fiber is carbon black and/or an inorganic filler. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the same, and more particularly, to a rubber composition having an increased orientation by containing a cup-stacked vapor grown carbon fiber and a tire using the rubber composition.

  In general, to increase tire motion performance, especially traction grip power during straight transmission, braking, etc., tread rubber is required to increase energy loss (hysteresis loss) while maintaining softness. In order to transmit the force from the side, it is necessary to increase the rigidity and increase the transmission force.

  As a technique for improving the high hysteresis loss characteristics of a rubber composition, for example, Patent Document 1 includes a predetermined amount of a polymer obtained by cationic polymerization using a Lewis acid catalyst as an initiator for a rubber component. Thus, a rubber composition and a pneumatic tire are described that have improved high hysteresis loss without deteriorating fracture characteristics. Patent Document 2 discloses a rubber composition that can provide excellent high hysteresis loss characteristics and fracture resistance characteristics by containing a rubber component and a softening agent composed of predetermined asphalt and process oil. A technique for realizing is described.

  Furthermore, a technique for improving physical properties by incorporating vapor grown carbon fibers in the rubber composition is also known. For example, Patent Documents 3 and 4 disclose vapor grown carbon fibers and rubber components for rubber components. A rubber composition in which various physical properties are improved by blending carbon black in a predetermined amount is described.

  On the other hand, in Patent Document 5, for the purpose of obtaining high thermal conductivity, 0.1 to 100 carbon fibers by a vapor phase growth method including one or more carbon network layers having a cup shape without a bottom as a filler are used. A rubber composition containing parts by mass is disclosed.

JP 2000-109610 A (Claims etc.) JP 2003-2143040 A (Claims etc.) JP-A-1-287151 (Claims etc.) Japanese Patent Laid-Open No. 1-289843 (Claims etc.) International Publication No. 2003/102073

  However, as described in Patent Documents 1 and 2, the method of adding a polymer or a softening agent obtained by cationic polymerization using a Lewis acid catalyst as an initiator has an effect on hysteresis loss, but has a circumferential elasticity. The rate was not considered. In addition, as described in Patent Documents 3 and 4, the method of blending a predetermined amount of vapor-grown carbon fiber and carbon black is effective for hysteresis loss and elastic modulus, but today, more excellent circumferential elastic modulus and Hysteresis loss is required.

  Furthermore, in Patent Document 5, high thermal conductivity can be obtained by using a rubber composition containing carbon fibers by a vapor phase growth method composed of one or more carbon network layers having a cup shape having no bottom. However, the rubber composition having high hysteresis loss and high circumferential modulus has not been sufficiently studied.

  Accordingly, an object of the present invention is to use a rubber composition that exhibits high hysteresis loss and a high circumferential elastic modulus (E ′) while maintaining mechanical properties, and has high grip properties when applied to a tire, and the rubber composition. To provide tires.

  Furthermore, the other object of this invention is to provide the rubber composition which can improve the durability as a tire by improved thermal conductivity, and a tire using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that both the flexibility of the tread rubber and the rigidity in the necessary direction (in the case of a tire, particularly the elastic modulus in the circumferential direction) can be achieved in a conventional manner. However, it was difficult to achieve this, but by introducing cup-stacked vapor-grown carbon fibers into a rubber composition of a specific composition and making good use of its orientation, circumferential rigidity (elastic modulus) and hysteresis loss The present invention has been completed.

  That is, the rubber composition of the present invention has a carbon fiber content of 0.1 to 80 parts by mass using a vapor phase growth method comprising 100 parts by mass of rubber and at least one carbon net layer having a cup shape having no bottom as a filler. 60 to 150 parts by mass of the filler and the filler other than the carbon fiber are blended.

  In the rubber composition of the present invention, the filler other than the carbon fiber is preferably carbon black and / or an inorganic filler.

  Furthermore, in the rubber composition of the present invention, it is preferable that the end face of the carbon mesh layer of the large-diameter portion of the cup laminated on the outer peripheral portion of the carbon fiber is exposed, and the carbon fiber does not have a bottom portion. Preferably, the carbon fiber is a carbon fiber formed by a vapor phase growth method in which a plurality of carbon network layers having a shape are stacked. Furthermore, in the rubber composition of the present invention, it is preferable that the carbon fiber has a hollow shape having no nodes.

  Furthermore, in the rubber composition of the present invention, it is preferable that the outer surface side of the hollow part of the hollow carbon fiber and the end surface of the carbon network layer on the inner surface side are exposed, and the outer surface of the hollow part It is preferable that 2% or more of the end surface of the carbon network layer on the side is exposed, and the exposed surface portion of the end surface of the carbon network layer preferably has unevenness of atomic level. .

  Furthermore, it is preferable that the rubber composition of the present invention is not graphitized even when the carbon network layer is heat-treated at a high temperature of 2500 ° C. or higher.

  Furthermore, in the rubber composition of the present invention, the carbon fiber preferably has a diameter of 1 to 1000 nm and a length of 0.1 to 1000 μm, and the carbon fiber has a diameter of 5 to 500 nm and a length of 0.00. The diameter is preferably 5 to 750 μm, and the carbon fiber preferably has a diameter of 10 to 250 nm and a length of 1 to 500 μm.

  The tire of the present invention is characterized by using the rubber composition.

  According to the present invention, there are provided a rubber composition that exhibits high hysteresis loss and a high circumferential elastic modulus (E ′) while maintaining mechanical properties, and has a high grip property when applied to a tire, and a tire using the rubber composition can do. Furthermore, the rubber composition which can improve the durability as a tire by improved thermal conductivity, and a tire using the same can be provided.

It is a schematic diagram which shows the carbon fiber by the vapor phase growth method in which the carbon net layer which makes the cup shape which does not have the bottom part which concerns on this invention was laminated | stacked. 1 is a schematic diagram of a carbon fiber having a herringbone structure manufactured by a vapor deposition method based on Example 1. FIG. FIG. 3 is a schematic diagram of a carbon fiber having a herringbone structure obtained by heat treating the carbon fiber shown in FIG. 2 at a temperature of about 530 ° C. for 1 hour in the air.

Embodiments of the present invention will be specifically described below.
The rubber composition of the present invention is 0.1 to 80 parts by mass of carbon fiber by vapor phase growth method consisting of one or more cup-shaped carbon network layers having no bottom as a filler in 100 parts by mass of rubber, Preferably, 20 to 40 parts by mass and 60 to 150 parts by mass, preferably 70 to 90 parts by mass of a filler other than carbon fiber are blended. When the blending amount of the carbon fiber is within this range, not only sufficient thermal conductivity, but also high mechanical loss and high elastic modulus (E ') in the circumferential direction are developed while maintaining the mechanical properties, and high grip performance. Have Further, if the filler other than carbon fiber is less than 60 parts by mass, sufficient high hysteresis loss cannot be obtained. On the other hand, if the filler other than carbon fiber exceeds 150 parts by mass, moderate flexibility as a tread is obtained. Is not preferable.

  Examples of the rubber used in the present invention include natural rubber, general-purpose synthetic rubber, such as emulsion polymerization styrene-butadiene rubber, solution polymerization styrene-butadiene rubber, high cis-1,4 polybutadiene rubber, low cis-1,4 polybutadiene rubber, High cis-1,4 polyisoprene rubber, etc. Diene special rubber, for example, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, etc., Olefin special rubber, for example, ethylene-propylene rubber, butyl rubber, halogenated butyl rubber, acrylic rubber And other special rubbers such as chlorosulfonated polyethylene, such as hydrin rubber, fluorine rubber, polysulfide rubber, and urethane rubber. From the balance between cost and performance, natural rubber or general-purpose synthetic rubber is preferable.

  The rubber composition according to the present invention includes a method of adding sulfur, a peroxide, a metal oxide, etc. and crosslinking by heating, a method of adding a photopolymerization initiator and crosslinking by light irradiation, an electron beam, It is preferably used after being vulcanized, for example, by a method of crosslinking by irradiation with radiation.

  Although it does not specifically limit as fillers other than carbon fiber used by this invention, It is preferable that they are carbon black and / or an inorganic filler, and other various fillers. There is no restriction | limiting in particular as carbon black, Arbitrary things can be selected and used from what is conventionally used as a reinforcing filler of a rubber composition. Specific examples include FEF, SRF, HAF, ISAF, SAF and the like, and iodine adsorption (IA) of 60 mg / g or more and dibutyl phthalate oil absorption (DBP) of 80 ml / 100 g or more are preferable. Among these, HAF, ISAF, and SAF, which are excellent in wear resistance, are preferable.

As the inorganic filler, those conventionally used in the rubber industry can be used and are not particularly limited. For example, alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina, boehmite, diaspo, etc. Alumina monohydrate (Al ₂ O ₃ .H ₂ O), aluminum hydroxide [Al (OH) ₃ ] such as gibbsite, bayerite, aluminum carbonate (Al ₂ (CO ₃ ) ₃ ), magnesium hydroxide [Mg _(OH) 2], magnesium oxide (MgO), magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white _(TiO 2), Titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca (OH) ₂ ], aluminum oxide mug Nesium (MgO.Al ₂ O ₃ ), clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ .4SiO ₂ .H ₂₎ O), bentonite (Al ₂ O ₃ .4SiO ₂ .2H ₂ O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ .3SiO ₄ .5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃₎ Etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide (ZrO (OH) ₂ .nH ₂ O), zirconium carbonate (ZrCO ₃ ), crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals that correct the charge, such as various zeolites, and the like. Among these, silica and nitrogen adsorption specific surface area (N ₂ SA) 1 to 20 m ² / g aluminum hydroxide is preferred, and silica is particularly preferred.

  There is no restriction | limiting in particular as a silica, It can select and use arbitrarily from what is conventionally used as a reinforcing material of rubber | gum. For example, wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate and the like can be mentioned. Among them, synthetic silica by precipitation method is preferable. In addition, the filler used by this invention can also use together 2 or more types of fillers, such as using together carbon black and a silica, for example.

  The carbon fiber used as a filler in the present invention is a carbon fiber formed by a vapor phase growth method composed of one or more carbon net layers having a cup shape without a bottom, and preferably has a cup shape without the bottom. The carbon fiber is a carbon fiber formed by vapor phase growth method in which a plurality of carbon network layers are formed, and the end surface of the carbon network layer of the large-diameter portion of the cup laminated on the outer peripheral portion of the carbon fiber is exposed. Specific examples include vapor-grown carbon fibers (1100C-treated product) and vapor-grown carbon fibers (1500C-treated product) manufactured by GSI Creos, which are disclosed in International Publication No. 2003/102073 pamphlet. Can be suitably used.

  FIG. 1 is a schematic view showing a carbon fiber formed by a vapor phase growth method in which a plurality of carbon network layers having a cup shape without a bottom according to the present invention are stacked. A feature is that the carbon network layer is laminated so that the portion indicated by 1 has no bottom and overlaps. Moreover, since these carbon network layers which do not have a bottom part are laminated | stacked, the carbon fiber of this invention makes a hollow shape without a node. Moreover, it is preferable that the part shown by 2 is an end surface of the carbon net layer of the large diameter part of the cup laminated | stacked on the outer peripheral part, and this part is the exposed state. Further, it is more preferable that the portions indicated by 3 and 4 are the outer surface and the inner surface of the hollow portion of the carbon fiber, and the end face of the carbon network layer of this portion is exposed.

  FIG. 2 is a schematic view of a carbon fiber having a herringbone structure. Here, 10 is an inclined carbon network layer, and 14 is a central hole, and a deposited layer 12 in which amorphous surplus carbon is deposited is formed so as to cover the carbon network layer 10.

  When carbon fiber is produced by the vapor phase growth method, herringbone whose carbon network layer is inclined at a certain angle with respect to the fiber axis is controlled by controlling the vapor phase growth conditions such as the catalyst, temperature range, and flow rate. Although a (herring-bone) structure can be manufactured, the carbon fiber according to the present invention has such a herringbone structure.

  In addition, a thin deposition layer is formed on the surface of the carbon fiber manufactured by the vapor phase growth method, in which amorphous surplus carbon that is not sufficiently crystallized is deposited. This deposited layer is considered to have low activity and therefore poor adhesion to rubber.

  In the carbon fiber according to the present invention, it is preferable that a part of the deposited layer 12 covering the carbon network layer 10 is removed and at least a part of the end surface (six-membered ring end) of the carbon network layer is exposed. The exposed end face of the carbon network layer 10 is easily associated with other atoms and has a very high activity. In the carbon fiber according to the present invention, at least 2% of the end face (six-membered ring end) of the carbon net layer is preferably exposed, and more preferably 7% or more is exposed. By this, the carbon fiber which concerns on this invention can improve adhesiveness with rubber | gum, and can obtain the rubber composition excellent in thermal conductivity. Therefore, from the above viewpoint, it is preferable that the rate of exposure of the end face of the carbon network layer is larger.

  Further, the carbon fiber according to the present invention can further expose the end face of the carbon network layer by more positively removing the deposited layer. This is because oxygen layer such as phenolic hydroxyl group, carboxyl group, quinone type carbonyl group and lactone group is formed on the end face of the exposed carbon network layer at the same time as the deposited layer 12 is removed by heat treatment in the atmosphere described later. It is considered that functional groups increase, and these oxygen-containing functional groups increase hydrophilicity and affinity for various substances.

  There are various methods for removing the deposited layer 12 and exposing the carbon network layer 10, but the temperature is 400 ° C. or higher, preferably 500 ° C. or higher, more preferably 520 ° C. or higher and 530 ° C. or lower. There is a method of heating for several hours, whereby the deposited layer 12 is oxidized and thermally decomposed. The deposited layer 12 can also be removed by a method of cleaning carbon fibers with supercritical water, a method of immersing in hydrochloric acid or sulfuric acid, and heating to about 80 ° C. while stirring with a stirrer, and the end face of the carbon network layer is exposed. Can be made.

  FIG. 3 is a schematic view of carbon fiber obtained by heat-treating the carbon fiber having the herringbone structure shown in FIG. 2 at a temperature of about 530 ° C. for 1 hour in the atmosphere. It can be seen that by performing the heat treatment as described above, a part of the deposited layer 12 is removed, and the end face (carbon six-membered ring end) of the carbon network layer 10 is exposed. It should be noted that the remaining deposited layer 12 is also almost decomposed and seems to be merely attached. It is also possible to remove 100% of the deposited layer 12 by performing heat treatment for several hours and using cleaning with supercritical water together.

In addition, in a Raman spectrum after heat-treating at 500 ° C., 520 ° C., 530 ° C., and 540 ° C. for 1 hour, respectively, the carbon fiber having a herringbone structure (sample name: Pristine 24PS, average outer diameter 100 nm) was left at 1 hour in the atmosphere. ^Since the peak of ^{−1 and} the peak of 1580 cm ⁻¹ exist, it was confirmed that these were carbon fibers and carbon fibers not having a graphitized structure.

  As shown in FIG. 3, the carbon fiber according to the present invention is composed of one or more carbon net layers having a cup shape without a bottom portion, and usually several to hundreds of thousands are laminated. Since these form fine particles, the dispersibility in rubber and resin is extremely good. Particularly in a composite material with rubber, not only is it supple and high in strength, but also a rubber composition having high adhesion to rubber and excellent thermal conductivity can be obtained.

  Further, the carbon fiber according to the present invention is preferably hollow with no nodes, and preferably has a hollow shape in the range of at least several tens of nanometers to several tens of micrometers as shown in FIG. In the hollow carbon fiber, it is preferable that the end surfaces of the carbon network layer on the outer surface side and the inner surface side of the hollow portion are exposed, and the higher the exposure ratio, the better. Of these, 2% or more of the carbon network layer is preferably exposed on the outer surface, and more preferably 7% or more is exposed. The inclination angle of the carbon network layer with respect to the center line is about 20 degrees to 35 degrees.

  Further, in the carbon fiber according to the present invention, it is preferable that a portion of the surface where the end face of the carbon network layer is exposed exhibits the unevenness 16 having an atomic level. The irregularities 16 have an anchoring effect on rubber, further improve adhesion to rubber, and can be a thermally excellent rubber composition.

  The unevenness 16 having the atomic level is considered to be due to a (grind) turbostratic structure in which the carbon network surface is shifted. In this turbostratic carbon fiber, each carbon hexagonal network surface has a parallel laminated structure, but each hexagonal network surface has a laminated structure that is shifted or rotated in the plane direction, and has crystallographic rules. Does not have sex.

  The carbon fiber according to the present invention is characterized in that normal carbon fiber is graphitized by high-temperature treatment at 2500 ° C. or higher, but does not graphitize even when heat-treated at 2500 ° C. or higher. The reason why the graphitization treatment does not cause graphitization is considered to be that the deposited layer 12 that is easily graphitized is removed. On the other hand, the portion of the herringbone structure remaining after removing the deposited layer 12 is graphite. It is because it does not become. This indicates that the carbon fiber according to the present invention is thermally stable.

In the Raman spectrum of carbon fibers having a herringbone structure with different outer diameters before heat treatment, Pristine 19PS has an average outer diameter of 150 nm, and Pristine 24PS has an average outer diameter of 100 nm. Further, even when measuring the Raman spectra after regular graphitized at 3000 ° C. of the same specimen, no significant change in the spectrum in both, since the presence of the peak of the peak and 1580 cm ^-1 in 1360 cm ^-1 It can be seen that the carbon fiber according to the present invention is not graphitized in a normal graphitization treatment.

  The diameter of the carbon fiber according to the present invention is preferably in the range of 1 to 1000 nm, more preferably in the range of 5 to 500 nm, and particularly preferably in the range of 10 to 250 nm. Further, the length is preferably in the range of 0.1 to 1000 μm, more preferably 0.5 to 750 μm, and particularly preferably in the range of 1 to 500 μm. By adjusting the diameter and length within this range, the affinity with rubber can be further increased, which is effective in improving thermal conductivity.

The carbon fiber according to the present invention can be produced, for example, by the following method.
A herringbone having a diameter of about 100 nm is prepared by charging a hydrocarbon such as benzene into a normal reaction vessel at a constant partial pressure, using a transition metal complex such as ferrocene as a catalyst, and setting the reaction temperature to about 1100 ° C. and the reaction time to about 20 minutes. A carbon fiber having a structure is obtained. By adjusting the flow rate of the raw material and the reaction temperature, a number of cup-shaped carbon network layers that do not have a bottom are stacked, and the hollow carbon fiber has no nodes (bridges) over a range of several tens of nanometers to several tens of micrometers Is obtained. Since the carbon fiber has a deposited layer as described above, at least a part of the carbon fiber is removed by the method described above. The carbon fiber produced in this way is a short fiber (several tens of μm in length) having a cup shape without a bottom portion, that is, a unit carbon network layer having a cross-section of a C-shaped cross section. ). This short fiber has a large molecular weight (length) and is insoluble in water, organic solvents, etc. The carbon fiber according to the present invention has one or more, preferably several, unit carbon network layers of these short fibers. ~ Divided into tens of thousands.

  There are various methods for dividing the short fiber to obtain the carbon fiber according to the present invention. For example, a method of adding an appropriate amount of water or a solvent and gently grinding with a pestle for an appropriate time using a mortar is suitable. is there. This is because the annular carbon network layer has a relatively high strength, and the carbon network layers are bonded by a weak van der Waals force. This is because the layers are separated.

  It is preferable that the above short fibers are ground in liquid nitrogen with a mortar and can be effectively divided. When liquid nitrogen evaporates, moisture in the air is absorbed and becomes ice, and short fibers are crushed with a pestle together with ice, reducing mechanical stress and allowing easy separation between unit fiber layers. It is. The division step can be performed before the deposition layer is removed, or the deposition layer can be removed after the division step.

  Moreover, it is preferable that the said division | segmentation process industrially grind-processes the said carbon fiber by ball milling. Hereinafter, a method of adjusting the length of the carbon fiber by ball milling will be described in detail. As the ball mill, for example, a product made by Asahi Rika Seisakusho can be used, and a ball made of alumina having a diameter of 5 mm can be used. As a specific example, for example, 1 g of the above carbon fiber, 200 g of alumina balls, and 50 cc of distilled water can be put in a cell and processed at a rotational speed of 350 rpm. When a sample is taken every 1, 3, 5, 10, 24 hours elapsed when divided by the above method and measured using a laser particle size distribution meter, the line length becomes shorter as the milling time elapses. After 10 hours, the line length is abruptly shortened to 10 μm or less. In addition, after 24 hours, another peak occurs around 1 μm, and the line length becomes finer. In addition, since the length and diameter of the peak around 1 μm are almost equal, it is considered that the length and the diameter are counted twice.

  The carbon fiber before milling is entangled with carbon fibers having a length of several tens of μm, and the bulk density is extremely low. On the other hand, as the milling time elapses, the line length becomes shorter. It is almost particulate after time. Furthermore, after the lapse of 24 hours, the fibers are hardly entangled and become high in bulk density.

  Furthermore, the carbon fiber is divided not by the fiber being broken but by being pulled out of a carbon net layer having a cup shape having no bottom.

  Next, the length was adjusted so that several dozen carbon network layers having a cup shape with no bottom were laminated. The carbon fiber had a length and a diameter of about 60 nm, a thin wall, and a large hollow portion. It has a tube shape, that is, a hollow shape without a node, and the end surface of the carbon net layer on the outer surface side and the inner surface side of the hollow portion is exposed. In this way, the carbon network layer having a cup shape without a bottom is separated out so that the shape of the carbon network layer is not broken. In addition, it can adjust to carbon fiber of arbitrary length according to the conditions of milling, and it is preferable to set it as the diameter and length of the suitable range of this invention mentioned above.

  In addition, when grinding normal carbon nanotubes having a concentric shape, the tube is cracked, the outer surface is cracked in the axial direction, or is raised and raised, and the so-called core is removed. It is difficult to adjust the height.

  In the present invention, as a method for mixing and molding the rubber composition, a known method used for ordinary rubber mixing and molding can be used, and there is no particular limitation.

  Furthermore, the rubber composition of the present invention can greatly improve thermal conductivity by blending a small amount of the above-mentioned carbon fiber without significantly changing other physical properties and without sacrificing molding processability. Therefore, it can be widely used for electric and electronic parts, tires, belts, and other various products. In the rubber composition of the present invention, additives generally used in the rubber industry, for example, usual rubber additives such as a vulcanization accelerator, a reinforcing material, an anti-aging agent, and a softening agent are appropriately used. It is possible.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Examples 1-3, Comparative Example 1
Carbon fiber and various additives are blended in oil-extended SBR (35 parts oil-extended) with the blending contents shown in Tables 1 and 2 below, and the vulcanized rubber composition according to the following kneading conditions and sheet preparation conditions Table 2 shows the results of preparing a sheet of the product and evaluating the viscoelasticity and mechanical behavior (tensile test) using the sheet. In addition, all the compounding quantities in Table 1 and Table 2 represent a mass part.

(1) Kneading conditions After scouring oil-extended SBR at 110 rpm at 70 rpm for 3 minutes using a lab plast mill (manufactured by Toyo Seiki Co., Ltd.), vulcanization accelerators shown in Tables 1 and 2 and Each additive except sulfur was added and further mixed at 110 ° C. at 70 rpm (non-pro blending). The obtained mixture was taken out, cooled and weighed, and then the remaining vulcanization accelerator and sulfur were added and mixed again at 50 rpm at 80 ° C. using a plastic bender (professional blending).

(2) Sheet preparation conditions The kneaded mixture was vulcanized at 150 ° C. for 15 minutes using a high-temperature press to prepare a vulcanized rubber sheet having a thickness of 2 mm.

(Thermal conductivity)
The thermal conductivity was measured using a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Co., Ltd., and the value of Comparative Example 1 was evaluated as 100.

(Elastic modulus (E ') and loss tangent)
Using a viscoelasticity measurement system (Rheograph) manufactured by Toyo Seiki Co., Ltd., the elastic modulus (E ′) and loss tangent (tan δ) at a temperature of 30 ° C. were measured under the conditions of 50 Hz and 2% strain. Evaluation was made with a value of 1 being 100.

(Tensile strength and elongation at cutting)
A tensile test was performed at room temperature in accordance with JIS K 6251, the tensile strength (Tb) and elongation at break (Eb) of the vulcanized rubber were measured, and the value of Comparative Example 1 was evaluated as 100.

＊１ 日本合成ゴム社製、０１２０（スチレン含有量３５％、ビニル量１６％、３５％アロマ油展）

* 1 Nippon Synthetic Rubber Co., Ltd. 0120 (styrene content 35%, vinyl content 16%, 35% aroma oil exhibition)

＊２ ＧＳＩクレオス社製、１１００Ｃ処理品
＊３ ＧＳＩクレオス社製、１５００Ｃ処理品

* 2 GSI Creos, 1100C treated product * 3 GSI Creos, 1500C treated product

  As apparent from the results in Table 2, 0.1 to 80 parts by mass of the cup-stacked carbon net layer carbon fiber and 60 to 150 parts by mass of a filler (carbon black, silica, etc.) other than the carbon fiber are blended. Thus, a rubber composition having a high hysteresis loss and a high elastic modulus in the circumferential direction can be obtained basically without impairing mechanical properties. Further, the improvement in thermal conductivity obtained not only contributes to shortening of the vulcanization time at the time of tire production, but also contributes as a heat dissipation effect of the heat generation of the tire during running, resulting in an improvement in the durability of the tire. It leads to.

1: bottom part 2: end face of carbon mesh layer of large-diameter part of cup laminated on outer peripheral part 3: outer surface of hollow part of carbon fiber 4: inner surface of hollow part of carbon fiber 10: carbon network layer 12: deposited layer 14: Central hole 16: Atomic level size irregularities

Claims (13)

  100 parts by mass of rubber, 0.1 to 80 parts by mass of carbon fiber by vapor phase growth method comprising at least one carbon net layer having a cup shape having no bottom as a filler, and fillers other than the carbon fiber 60 to 150 parts by mass of a rubber composition.   The rubber composition according to claim 1, wherein the filler other than the carbon fiber is carbon black and / or an inorganic filler.   The rubber composition according to claim 1 or 2, wherein an end face of the carbon net layer of the large-diameter portion of the cup laminated on the outer peripheral portion of the carbon fiber is exposed.   The rubber composition according to claim 3, wherein the carbon fiber is a carbon fiber formed by a vapor phase growth method in which a plurality of carbon network layers having a cup shape having no bottom portion are stacked.   The rubber composition according to claim 4, wherein the carbon fiber has a hollow shape without a node.   The rubber composition according to claim 5, wherein end surfaces of the carbon surface layer on the outer surface side and the inner surface side of the hollow portion of the hollow carbon fiber are exposed.   The rubber composition according to claim 6, wherein 2% or more of the end face of the carbon net layer on the outer surface side of the hollow portion is exposed.   The rubber composition according to claim 6 or 7, wherein a portion of the exposed surface of the end face of the carbon network layer has unevenness of an atomic level.   The rubber composition according to any one of claims 1 to 8, wherein the carbon network layer is not graphitized even when heat-treated at a high temperature of 2500 ° C or higher.   The rubber composition according to any one of claims 1 to 9, wherein the carbon fiber has a diameter of 1 to 1000 nm and a length of 0.1 to 1000 µm.   The rubber composition according to any one of claims 1 to 9, wherein the carbon fiber has a diameter of 5 to 500 nm and a length of 0.5 to 750 µm.   The rubber composition according to any one of claims 1 to 9, wherein the carbon fiber has a diameter of 10 to 250 nm and a length of 1 to 500 µm. A tire using the rubber composition according to any one of claims 1 to 12.

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