JP2016124921A - Rubber compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel rubber compound efficiently enhancing durability especially when used for a tire member such as a tire tread while inhibiting increase of cost.SOLUTION: There is provided a rubber compound by blending a petroleum coke fine pulverized article having average particle diameter (D50) of over 0 μm and 50 μm or less and carbon black to natural rubber, preferably the petroleum coke fine pulverized article manufactured by pulverizing coke obtained by thermal decomposition of atmospheric distillation residue oil or vacuum distillation residue oil of crude oil or the petroleum coke fine pulverized article of 1 to 500 pts.mass and the carbon black of 1 to 500 pts.mass are blended to 100 pts.mass of the natural rubber.SELECTED DRAWING: None

Description

  The present invention relates to rubber compounds.

  In rubber compounds for tire members such as tire treads, rubber components such as natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and polybutadiene rubber (BR) are further mixed and processed with rubber elasticity. In order to improve various properties such as wear resistance and mechanical properties, various compounding components are added according to the type and molecular weight of the rubber component (for example, Patent Document 1 (Japanese Patent Laid-Open No. 2001-30714). No.)).

  For example, when natural rubber is used as a rubber component in a rubber compound for a tire member such as a tire tread, silica, aluminum hydroxide, alumina, calcium carbonate, magnesium carbonate, magnesium hydroxide are used to improve durability. , Magnesium oxide, Titanium oxide, Potassium titanate, Carbon black, Barium sulfate, and other inorganic fillers are blended. These inorganic fillers reduce the properties of rubber components and increase costs. It has become.

  On the other hand, industrial vehicles such as trucks and forklifts transport or convey heavy objects, and as a result of applying high loads to the tires, the tires are likely to wear out or break or tear such as chip cuts. Therefore, it is required to provide a rubber compound used for a tire member such as a tire tread, which is a consumable, at low cost while effectively improving durability.

JP 2001-30714 A

  Under such circumstances, an object of the present invention is to provide a novel rubber compound that effectively improves durability when used in tire members such as tire treads while suppressing an increase in cost. To do.

  As a result of intensive studies by the present inventors in order to solve the above technical problem, natural rubber was adopted as the rubber component, and petroleum coke finely pulverized product having a particle size in a specific range and carbon black were adopted as the inorganic filler. The present inventors have found that the above technical problem can be solved by the rubber compound, and have completed the present invention based on this finding.

That is, the present invention
(1) A rubber compound characterized by comprising a petroleum coke finely pulverized product having an average particle size (D50) of more than 0 μm and not more than 50 μm and carbon black to natural rubber,
(2) The rubber compound according to the above (1), wherein the finely pulverized petroleum coke is obtained by pulverizing coke obtained by thermally decomposing crude oil atmospheric distillation residue oil or vacuum distillation residue oil,
(3) The above-mentioned (1) or (2), wherein 1 to 500 parts by mass of the finely pulverized petroleum coke and 1 to 500 parts by mass of the carbon black are blended with respect to 100 parts by mass of the natural rubber. Rubber compound,
(4) The rubber compound according to any one of (1) to (3), wherein the rubber compound is used for a tire member.

  ADVANTAGE OF THE INVENTION According to this invention, the novel rubber compound which improves durability effectively, especially when used for tire members, such as a tire tread, can be provided, suppressing a raise of cost.

  The rubber compound of the present invention is characterized by compounding a finely pulverized petroleum coke having an average particle size (D50) of more than 0 μm and not more than 50 μm and carbon black.

  In the rubber compound of the present invention, the natural rubber is not particularly limited. For example, when the rubber compound of the present invention is used for a tire member such as a tire tread, SIR20, RSS # 3, TSR20, desorption. One or more kinds selected from protein natural rubber (DPNR), high-purity natural rubber (HPNR) and the like can be mentioned.

  In the rubber compound of the present invention, the number average molecular weight of natural rubber is not particularly limited, and the number average molecular weight is preferably 2 million or more, more preferably 2.5 million or more.

In the rubber blend of the present invention, the blending ratio of natural rubber (content ratio of natural rubber) is:
It is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, and further preferably 30 to 85% by mass.

  The rubber compound of the present invention is obtained by blending a natural rubber with a finely pulverized petroleum coke having an average particle size (D50) of more than 0 μm and 50 μm or less.

  In the rubber compound of the present invention, the petroleum coke fine pulverized product is a pulverized product obtained by pulverizing petroleum coke, and is a pulverized product obtained by finely pulverizing petroleum coke by a pulverizing means.

  Petroleum coke, which is a pulverized raw material, is produced by pyrolyzing raw oil produced in the petroleum refining process by pyrolysis treatment in a pyrolysis device, and remains after collecting light components produced in the pyrolysis treatment. .

  The pyrolysis raw oil to be pyrolyzed includes atmospheric distillation residue oil after crude oil distillation, atmospheric distillation residue oil after distillation of atmospheric distillation residue oil, and atmospheric distillation residue oil. A mixed oil of a vacuum distillation residue oil or a mixed oil of at least one of an atmospheric distillation residue oil and a vacuum distillation residue oil and another hydrocarbon oil (1) may be mentioned.

  There is no restriction | limiting in particular in the atmospheric distillation residue oil which concerns on a pyrolysis raw material oil, It is a residue part after carrying out atmospheric pressure distillation and isolate | separating an evaporation fraction. There is no restriction | limiting in particular in the vacuum distillation residue oil which concerns on a pyrolysis raw material oil, It is a residue part after carrying out vacuum distillation of the atmospheric distillation residue oil, and isolate | separating an evaporation fraction. The pyrolysis raw material oil may be a mixed oil of atmospheric distillation residue oil and vacuum distillation residue oil. When the pyrolysis raw oil is a mixture oil of atmospheric distillation residue oil and vacuum distillation residue oil, The mixing ratio of the distillation residue oil and the vacuum distillation residue oil is not particularly limited, and is appropriately adjusted.

  The crude oil used as the distillation raw material for the atmospheric distillation residue is not particularly limited, and examples of crude oil types include, for example, Arabian heavy, Arabian medium, Arabian light, Arabian extra light, Kuwait, Basra, Oman, Marban, Mubarras blend. , Zakum, Upper Zakum, Qatar Land, Qatar Marine, Umshaif, Shiri, Kafuji, Espo, etc., any one or a combination of two or more.

  The pyrolysis raw material oil is a mixed oil of at least one of atmospheric distillation residue oil and vacuum distillation residue oil and other hydrocarbon oil (1), that is, atmospheric distillation residue oil and other hydrocarbon oil. Mixed oil of (1), mixed oil of vacuum distillation residue oil and other hydrocarbon oil (1), or mixed oil of atmospheric distillation residue oil, vacuum distillation residue oil and other hydrocarbon oil (1) It may be. When the pyrolysis raw material oil is a mixed oil of at least one of atmospheric distillation residue oil and vacuum distillation residue oil and other hydrocarbon oil (1), the other hydrocarbon oil (1) is the present invention. For example, a slurry oil in a fluid catalytic cracking process, an ethylene cracker residue oil, or the like may be used.

  As conditions for the pyrolysis treatment, the pyrolysis temperature is preferably 490 to 510 ° C., more preferably 495 to 505 ° C., and the pressure (gauge pressure) during the pyrolysis treatment is preferably 0.01. It is -0.6 MPaG, More preferably, it is 0.05-0.4 MPaG.

  Moreover, the atmosphere of a thermal decomposition process is steam. Moreover, when excessive foaming is recognized during a thermal decomposition process, an antifoamer may be thrown in. As the antifoaming agent, a silicon-based antifoaming agent or the like can be generally used.

  Petroleum coke produced by pyrolysis of the pyrolysis feedstock is crushed using a water jet or the like after the pyrolysis treatment and taken out from the pyrolysis apparatus. The petroleum coke taken out from the pyrolyzer is generally granular in shape called shot coke, or in the form of a large porous porous shape generally called sponge coke. The pulverized raw material for producing slab may be shot coke, sponge coke, or a mixture thereof. Moreover, the petroleum coke taken out from the thermal decomposition apparatus is dried at a temperature of room temperature (20 ° C.) to 500 ° C. as necessary.

  Subsequently, the petroleum coke taken out from the thermal cracking apparatus is pulverized to obtain the finely pulverized petroleum coke of the present invention. The pulverization means for performing the pulverization process is not particularly limited, and may be dry or wet. Examples of the pulverizing means include pulverizers such as a jaw crusher, a joy crusher, a cone crusher, a hammer crusher, an autogenous pulverizer, a ball mill, a roller mill, a high-speed rotary mill, and a jet mill. The pulverization conditions are appropriately selected depending on the average particle size of the desired finely pulverized product, other particle size characteristics, pulverization means, number of pulverizations, and the like. The pulverized petroleum coke is classified as necessary.

In the rubber compound of the present invention, the average particle diameter (D50) of the finely pulverized petroleum coke is more than 0 μm and 50 μm or less.
In the rubber compound of the present invention, the average particle diameter (D50) of the finely pulverized petroleum coke is preferably 30 μm or less, more preferably 20 μm or less, further preferably 10 μm or less, and particularly preferably 5 μm or less.
In the rubber compound of the present invention, the average particle size (D50) of the finely pulverized petroleum coke is preferably 0.05 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more.
When the average particle size (D50) of the finely pulverized petroleum coke is within the above range, the dispersibility is enhanced, and when used as a filler of a rubber compound, the increase in cost is suppressed and the tensile of the rubber compound is suppressed. The strength can be easily improved.

In the finely pulverized petroleum coke, the following formula
(D90-D10) / D50 (I)
Is preferably 0.3 to 7, and more preferably 0.3 to 6.
In the rubber compound of the present invention, when the span of the finely pulverized petroleum coke is within the above range, the compounding conditions can be easily designed as a filler for the rubber compound.

In the rubber compound of the present invention, D90 of the finely pulverized petroleum coke is preferably 150 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less.
Moreover, in the rubber compound of the present invention, D10 of the finely pulverized petroleum coke is preferably 0.01 μm or more, more preferably 0.03 μm or more, and further preferably 0.05 μm or more.

  In the present application documents, D10, D50 (average particle size) and D90 of the finely pulverized petroleum coke are each measured by a volume frequency particle size distribution measurement using a laser diffraction / scattering particle size distribution measuring device based on JIS Z 8825. Mean particle size of 10%, 50% and 90%.

In the rubber compound of the present invention, the sulfur content of the finely pulverized petroleum coke is preferably 1 to 12% by mass, more preferably 2 to 10% by mass, and still more preferably 4 to 8% by mass in a dry state.
When sulfur content exists in the said range, affinity with the natural rubber which is a base material improves, and the dispersibility of petroleum coke fine ground material can be improved.
Since the coke obtained by the pyrolysis treatment of the pyrolysis raw material oil usually contains about 1 to 12% by mass of water, when the mass of the petroleum coke in a water-containing state is used as a reference for calculating the sulfur content, Depending on the water content of petroleum coke, the calculated value of sulfur content in petroleum coke will fluctuate. Therefore, in calculating the sulfur content in petroleum coke, water-containing petroleum coke is dried at 200 ° C. ± 10 ° C. for 4 hours (according to JIS M 8811), and the mass of the resulting dried petroleum coke is measured. The sulfur content in the petroleum coke is calculated based on the mass of the dried petroleum coke. That is, the sulfur content in the dry state of petroleum coke means the ratio of the mass of sulfur in petroleum coke to the mass of dry petroleum coke.

In the rubber compound of the present invention, the bulk density of the finely pulverized petroleum coke is preferably 0.1 to 1.0 g / cm ³ .
The upper limit of the bulk density of the petroleum coke grind, more preferably 0.8 g / cm ^3, more preferably ^{0.5g / cm 3, 0.4g / cm} 3 is particularly preferred.
The lower limit of the bulk density of the petroleum coke grind, more preferably 0.2 g / cm ^3, more preferably 0.3 g / cm ^3.

In the rubber compound of the present invention, the petroleum coke pulverized product preferably contains 70 to 90% by mass of carbon atoms and 1 to 10% by mass of hydrogen atoms.
In the present application documents, the carbon atom content and hydrogen atom content of the finely pulverized petroleum coke are values measured in accordance with JIS M 8813.

  In the rubber compound of the present invention, the finely pulverized petroleum coke contains carbon atoms and hydrogen atoms, usually in the form of hydrocarbon groups.

In the rubber compound of the present invention, it is confirmed by infrared absorption spectrum analysis (IR) that the petroleum coke fine pulverized product contains a hydrocarbon group. In the IR chart of the petroleum coke fine pulverized product, 2800 to 3000 cm ⁻ _CH around _{^{1, -C 2 H-, CH 3}} - telescopic peaks from vibration, the peak derived from the vicinity of 1600 cm ^-1 to the phenyl group C = C, CH around 1300～1500Cm ^-1, Confirmation is made by detecting at least one of the peaks derived from -C ₂ H-, CH _3- bending vibration and the peak derived from phenyl group C-H in the vicinity of 800 to 900 cm ^-1. Can do.

In the rubber compound of the present invention, the nitrogen content of the finely pulverized petroleum coke is preferably 0.1 to 2.0% by mass.
In addition, in this application document, the nitrogen content of a petroleum coke fine ground material means the value measured based on JISM8813.

In the rubber compound of the present invention, the aromatic carbon ratio of the petroleum coke pulverized product is preferably 75 to 98% by mass, and more preferably 85 to 95% by mass.
In the present application documents, the aromatic carbon ratio of the finely pulverized petroleum coke is the peak area intensity (100 to 200 ppm) of aromatic carbon (CA) in the ¹³ CNMR (nuclear magnetic resonance) spectrum. It means a value calculated by dividing by the area intensity (0 to 200 ppm). The ¹³ C-NMR spectrum means that measured by JEOL Ltd. Nuclear Magnetic Resonator Alpha-400 using deuterium chloroform as a solvent and tetramethylsilane (TMS) as an internal standard. .

In the rubber compound of the present invention, the fixed carbon content of the finely pulverized petroleum coke is preferably 70 to 95% by mass, and more preferably 75 to 90% by mass.
In addition, in this application document, the fixed carbon content of a petroleum coke fine ground material means the value measured based on JISM8812.

In the rubber compound of the present invention, the ratio (H / C molar ratio) of the number of moles in terms of hydrogen to the number of moles in terms of carbon of the finely pulverized petroleum coke is 0.1 to 1.0. It is preferable that it is 0.2 to 0.8.
In the present application documents, the ratio of the number of moles of hydrogen equivalent to the number of moles of carbon equivalent of the finely pulverized petroleum coke pulverized product (H / C mole ratio) is measured in accordance with JIS M 8813. It means a value calculated from the number of moles of hydrogen in terms of atoms relative to the number of moles of atoms in terms of carbon.

In rubber compounds for tire members such as tire treads, it may be possible to use carbon black as a carbon-based inorganic filler, but carbon black is a petroleum heavy oil or residual oil from ethylene production. It is manufactured by spraying continuously in a furnace in a high temperature atmosphere of 1400 ° C or higher to cause thermal decomposition, then spraying water and reacting while controlling the particle size, and further granulating. In addition, since the manufacturing process is multi-step and complicated, the cost of the rubber compound tends to increase.
On the other hand, petroleum coke obtained by pyrolyzing residual oil produced during petroleum refining has been simple and inexpensive in its production process, but has been used only as boiler fuel. Under such circumstances, as a result of intensive studies by the present inventors, surprisingly, petroleum coke having a particle size in a specific range is useful as an inorganic filler in a rubber compound containing natural rubber as a rubber component. In particular, the present inventors have found that the tensile strength of a rubber compound can be effectively improved even if the amount of carbon black is reduced, and the present invention has been completed.

The rubber compound of the present invention is preferably formed by blending 1 to 500 parts by mass of the above-mentioned finely pulverized petroleum coke with respect to 100 parts by mass of the natural rubber described above, and is composed of 5 to 300 parts by mass. More preferably, it is more preferably 10 to 200 parts by mass.
In the rubber compound of the present invention, the blending ratio of the finely pulverized petroleum coke (content ratio of the finely pulverized petroleum coke) is preferably 1 to 80% by mass, and preferably 4 to 70% by mass. More preferably, the content is 7 to 65% by mass.

  When the rubber compound of the present invention contains the above-mentioned finely pulverized petroleum coke in the above range, the tensile strength can be effectively improved.

  The rubber compound of the present invention is obtained by blending carbon black with natural coke finely ground petroleum coke having an average particle size (D50) of more than 0 μm and 50 μm or less.

  In the rubber compound of the present invention, the carbon black is not particularly limited, and known ones can be used, such as those used in ordinary rubber industry such as SAF, ISAF, HAF, FEF and GPF. Can be mentioned.

The rubber compound of the present invention is preferably formed by blending 1 to 500 parts by mass of the carbon black with respect to 100 parts by mass of the natural rubber described above, and is obtained by blending 5 to 300 parts by mass. More preferably, it is more preferably 10 to 200 parts by mass.
In the rubber compound of the present invention, the carbon black content (carbon black content) is preferably 1 to 80% by mass, more preferably 4 to 70% by mass, and 7 to 65%. More preferably, it is mass%.

  The rubber compound of the present invention contains the above-mentioned petroleum coke finely pulverized product, thereby reducing the content ratio of carbon black, thereby effectively improving the tensile strength while suppressing an increase in cost. be able to.

  The rubber compound of the present invention may be formed by blending an optional additive as required in addition to natural rubber, petroleum coke fine pulverized product, and carbon black.

  Additives may be appropriately selected from known ones. Processing of vulcanizing agents, vulcanization accelerators, vulcanization activators, organic peroxides, fillers, silane coupling agents, extender oils, lubricants, etc. One or more selected from auxiliaries, antioxidants and the like can be mentioned.

Examples of the vulcanizing agent include one or more selected from sulfur and the like.
In the rubber compound of the present invention, the compounding amount of the vulcanizing agent is preferably 0.1 to 10 parts by mass and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of natural rubber.
In the rubber compound of the present invention, the compounding ratio of the vulcanizing agent (the vulcanizing agent content ratio) is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and 0.7 More preferred is ˜2% by mass.

Examples of the vulcanization accelerator include 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and thiazole vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide, tetramethylthiuram monosulfide, and tetramethylthiuram. Thiuram-based vulcanization accelerators such as disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N -Sulfenamide vulcanization accelerators such as oxyethylene-2-benzothiazole sulfenamide, N, N'-diisopropyl-2-benzothiazole sulfenamide, diphenylguanidine, diortolylguanidine, orthotolylbiguanidine, etc. Gua One or more types selected from nidin vulcanization accelerators and the like can be mentioned.
0.1-5 mass parts is preferable with respect to 100 mass parts of natural rubber, and, as for the compounding quantity of a vulcanization accelerator, 0.2-3 mass parts is more preferable.

Examples of the vulcanization activator include one or more selected from stearic acid, zinc oxide and the like.
Examples of the filler include one or more selected from calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica and the like.

  As the extending oil, aromatic mineral oil (viscosity specific gravity constant (VGC value) 0.900 to 1.049), naphthenic mineral oil (VGC value 0.850 to 0) 899), paraffinic mineral oil (VGC value 0.790 to 0.849) and the like.

The rubber compound of the present invention preferably has a tensile strength of 5 to 45 MPa, more preferably 8 to 40 MPa, and still more preferably 10 to 35 MPa.
In the present application documents, the tensile strength means a value obtained by measuring a rubber compound of the present invention punched into a dumbbell-shaped No. 3 test piece according to JIS K 6251.

  The rubber compound of the present invention employs natural rubber as a rubber component, and by using petroleum coke fine pulverized product and carbon black having a particle size in a specific range as an inorganic filler, particularly improves tensile strength. When the tensile strength of the rubber compound of the present invention is within the above range, the rubber compound of the present invention is less prone to breakage, tearing, and the like with respect to torsional behavior under compression conditions due to high loads. Can be suitably used for a tire member such as a tire tread.

  The rubber compound of the present invention is a known method such as a roll or a banbury of an open roll mixer, such as natural rubber, petroleum coke finely pulverized product, carbon black, and additives optionally added as necessary. It can be produced by a kneading method using a known mixer.

The conditions at the time of kneading with the mixer are not particularly limited. When a vulcanizing agent or a vulcanization accelerator is not blended as an additive, the kneading temperature is suitably 50 ° C to 200 ° C, and 80 ° C to 190 ° C. The kneading time is suitably 30 seconds to 30 minutes, and more suitably 1 minute to 30 minutes.
Moreover, when mix | blending a vulcanizing agent and a vulcanization accelerator as an additive, kneading | mixing temperature is 100 degrees C or less suitably, and room temperature-80 degreeC are more suitable.

  In addition, when a vulcanizing agent or a vulcanization accelerator is blended, a desired rubber molded body can be obtained by molding it into a predetermined shape and then heating and curing as appropriate. In this case, the vulcanization temperature is suitably from 120 to 200 ° C., more preferably from 140 to 180 ° C., and the vulcanization time is suitably from 5 to 60 minutes. ~ 40 minutes is more appropriate.

  By the above method, the rubber compound of the present invention can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber compound which improves durability effectively can be provided, especially when used for tire members, such as a tire tread, suppressing a raise of cost.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

<Petroleum coke>
Using pyrolysis residue oil and slurry oil as pyrolysis raw material oil, pyrolysis treatment under conditions of 500 ° C. and 0.1 MPaG, pyrolysis treatment, pulverization with water jet, and visually, shot coke and sponge coke To make petroleum coke. Table 1 shows the properties of the shot coke and sponge coke.

The properties of petroleum coke are measured by the following method.
(moisture)
The measurement was performed according to JIS M 8811.
(CHN, H / C)
The measurement was performed according to JIS M 8813.
(Sulfur content)
The sulfur content was measured according to JIS M 8819.
(ash)
The measurement was performed according to JIS M 8812.
(Volatile)
The measurement was performed according to JIS M 8812.
(Fixed carbon content)
The measurement was performed according to JIS M 8812.
(Aromatic carbon ratio)
^The calculation was performed by dividing the peak area intensity (100 to 200 ppm) of aromatic carbon (CA) in the ¹³ CNMR (nuclear magnetic resonance) spectrum by the peak area intensity (0 to 200 ppm) of all carbons. The ¹³ C-NMR spectrum was measured with a nuclear magnetic resonance apparatus Alpha-400 manufactured by JEOL Ltd. using deuterium chloroform as a solvent and tetramethylsilane (TMS) as an internal standard.

<Drying of petroleum coke>
The petroleum coke obtained above was dried at room temperature (25 ° C.) all day and night (24 hours) to obtain a dried product of petroleum coke as a pulverized raw material. When the moisture content of the dried petroleum coke was measured, the moisture content of both the shot coke and sponge coke after drying was 1% by mass or less.

(Example 1 and Example 2)
<Pulverization of petroleum coke>
The dried shot coke obtained above was supplied to a cutter mill (VM-22 manufactured by Seishin Enterprise Co., Ltd.) and coarsely pulverized to obtain a coarsely pulverized product. Table 2 shows the grinding conditions and results at that time.
Subsequently, the obtained coarsely pulverized product was supplied to a jet mill (FS-4 manufactured by Seishin Enterprise Co., Ltd.) and finely pulverized to obtain a petroleum pulverized finely pulverized product. Table 2 shows the pulverization conditions and the analysis results of the finely pulverized product.
The particle size of the finely pulverized product is measured by the following method.
(Particle size distribution)
Volume frequency particle size distribution measurement is performed by a laser diffraction scattering method using a laser diffraction scattering type particle size distribution measuring device (Nikkiso Co., Ltd. MICROTRAC) in accordance with JIS Z 8825, and from the obtained volume frequency particle size distribution measurement results The integrated particle sizes of 10%, 50%, and 90% were obtained and were set as D10, D50 (average particle size), and D90, respectively.

Next, 100 parts by mass of natural rubber (RSS3 grade), 2 parts by mass of stearic acid (Lunac S-50V manufactured by Kao Corporation), 5 parts by mass of zinc oxide (manufactured by Hakusui Tech Co., Ltd.), TBBS (N- (tert -Butyl) -2-benzothiazole sulfenamide, Mitsui Chemicals Co., Ltd. Sunseller NS-G) 0.7 parts by mass, sulfur (Hosoi Chemical Co., Ltd.) 2.25 parts by mass, and each petroleum 65 parts by mass of finely pulverized coke and 35 parts by mass of carbon black (HAF grade) were mixed to prepare mixtures each containing finely pulverized petroleum coke.
After kneading each of the above mixtures with an open roll mixer, the obtained kneaded product was press vulcanized at 140 ° C. for 30 minutes to obtain each desired rubber compound.
Table 4 shows the blending ratio of the obtained rubber blends and the evaluation results thereof.

Each rubber compound was evaluated by the following method.
(Scorch time)
Using a Mooney scorch tester (S type rotor) conforming to JIS K6300, the t5 value (minute) at the time of measurement at a temperature of 120 ° C. was determined.
(Mooney viscosity)
According to JIS K 6300, Mooney viscosity (MS 120 ° C.) at a temperature of 120 ° C. was measured.
(hardness)
Based on JIS K6253, it measured using the durometer hardness meter.
(Tensile strength, elongation, 300% modulus)
Each rubber compound was punched into a dumbbell-shaped No. 3 test piece, and elongation (%), tensile strength (MPa), and 300% modulus were measured in accordance with JIS K 6251.
(specific gravity)
The measurement was performed according to JIS K6268.
(Permanent compression strain)
According to JIS K 6262, compression set after 24 hours was measured under the conditions of 70 ° C. and 25% compression.

(Comparative Example 1)
<Pulverization of petroleum coke>
The dried product of shot coke obtained by the above-described method is supplied to a cutter mill (VM-22 manufactured by Seishin Enterprise Co., Ltd.) and coarsely pulverized to obtain a coarsely pulverized product. And evaluated in the same manner. Table 2 shows the grinding conditions and evaluation results at that time.

  Next, using the obtained pulverized product, a rubber compound was prepared in the same manner as in Example 1, and the properties of the rubber compound obtained in the same manner as in Example 1 were evaluated. Table 4 shows the compounding ratio of the obtained rubber compound and the evaluation results.

(Example 3 and Example 4)
<Pulverization of petroleum coke>
The dried sponge coke obtained above was supplied to a cutter mill (VM-22 manufactured by Seishin Enterprise Co., Ltd.) and coarsely pulverized to obtain a coarsely pulverized product. Table 3 shows the grinding conditions and evaluation results at that time.
Subsequently, the obtained coarsely pulverized product was supplied to a jet mill (FS-4 manufactured by Seishin Enterprise Co., Ltd.) and finely pulverized to obtain a finely pulverized petroleum coke product. And evaluated in the same manner. Table 3 shows the grinding conditions and evaluation results at that time.
Next, each rubber compound was prepared in the same manner as in Example 1 using the obtained pulverized product, and the properties of each rubber compound obtained in the same manner as in Example 1 were evaluated. Table 4 shows the compounding ratio of the obtained rubber compound and the evaluation results.

(Comparative Example 2)
<Pulverization of petroleum coke>
The dried sponge coke obtained above is supplied to a cutter mill (VM-22 manufactured by Seishin Enterprise Co., Ltd.) and coarsely pulverized to obtain a coarsely pulverized product. The obtained pulverized product is the same as in Example 1. Evaluated. Table 3 shows the grinding conditions and evaluation results at that time.
Next, each rubber compound was prepared in the same manner as in Example 1 using the obtained pulverized product, and the properties of each rubber compound obtained in the same manner as in Example 1 were evaluated. Table 4 shows the compounding ratio of the obtained rubber compound and the evaluation results.

  From Table 2 to Table 4, in Examples 1 to 4, natural rubber is used as the rubber component, and an inexpensive petroleum coke fine pulverized product having an average particle diameter (D50) of more than 0 μm and 50 μm or less is used. Since the rubber compound is prepared, the tensile strength is high while reducing the production cost by reducing the amount of carbon black, and the durability is effective especially when used for tire treads and other tire members. It can be seen that it is possible to provide a rubber compound that can be improved significantly.

  On the other hand, from Tables 2 to 4, in Comparative Examples 1 to 2, the rubber compound is prepared using a finely pulverized petroleum coke having an average particle size (D50) exceeding 50 μm. It can be seen that the rubber compound has a low tensile strength and is inferior in durability, making it difficult to put it into practical use for tire treads and the like.

ADVANTAGE OF THE INVENTION According to this invention, the novel rubber compound which improves durability effectively, especially when used for tire members, such as a tire tread, can be provided, suppressing a raise of cost.

Claims (4)

  A rubber compound comprising a natural rubber blended with finely pulverized petroleum coke having an average particle size (D50) of more than 0 μm and not more than 50 μm, and carbon black.   The rubber compound according to claim 1, wherein the finely pulverized petroleum coke is obtained by pulverizing coke obtained by thermally decomposing crude oil atmospheric distillation residue oil or vacuum distillation residue oil.   The rubber compound according to claim 1 or 2, wherein 1 to 500 parts by mass of the finely pulverized petroleum coke and 1 to 500 parts by mass of the carbon black are blended with 100 parts by mass of the natural rubber. The rubber compound according to any one of claims 1 to 3, wherein the rubber compound is for a tire member.