JP2012177019A - Rubber composition for rim strip and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a rim strip in which rim rubbing properties and fatigue resistance are improved in good balance while keeping low exothermic properties and set resistance and which is excellent in durability, and to provide a pneumatic tire.SOLUTION: The carbon black-containing rubber composition for the rim strip satisfies the following (1)-(4). (1) Dibutyl phthalate (DBP) absorption (ml/100 g) is 90-180, (2) the difference between the BET specific surface area (BET5) (m/g) and the external specific area (STSA) (m/g) is 5≤(BET5)-(STSA)≤12, (3) the ratio of the stokes diameter (Dst) of the carbon black and the stokes diameter distribution (ΔD-50 (half value width) ) is 0.70≤(ΔD-50)/(Dst)≤1.10, and (4) the ratio of the BET specific surface area (BET5)(m/g) and the iodine adsorption (IA) (mg/g) is 1.05≤(BET5)/(IA)≤1.35.

Description

  The present invention relates to a rubber composition for a rim strip that contains a rubber component and carbon black and is useful as a raw material for a rim strip of a pneumatic tire, and maintains rim rubability while maintaining low heat buildup and set resistance. Further, the present invention relates to a rubber composition for a rim strip and a pneumatic tire having improved fatigue resistance in a well-balanced manner and excellent in durability.

  As shown in FIG. 1, generally in a pneumatic tire, a chacher 7 and a rim strip 8 are arranged via a carcass ply 5 on the inner side of the bead wire 1 and the bead filler 2 in the tire radial direction, and the rim strip 8 is a tire rim. Sit in contact with (not shown). At the contact portion between the rim strip and the tire rim, shear strain repeatedly acts during tire travel. Therefore, the rubber part constituting the rim strip is set to have high rigidity and rubber hardness, low heat generation, and wear resistance (rim It is important to improve (rubbing) and fatigue resistance. It is also important to improve the set resistance of the rim strip when considering the case of correcting the tire.

In the following Patent Document 1, the loss on heating from 150 ° C. to 450 ° C. is 0.87% by mass or more, the toluene coloring permeability is 90% or more, the nitrogen adsorption specific surface area (N ₂ SA) (m ² / g) and iodine A rubber composition containing carbon black having a ratio of 1.10 to 1.30 with the amount of adsorption (IA) (mg / g) and a processing aid that is at least one of a fatty acid ester and a fatty acid metal salt. It describes that both wear resistance and low heat build-up can be achieved. In Patent Document 2 below, the specific surface area (m ² / g) of cetyltriammonium (CTAB) is 115 to 145, and the ratio of DBP absorption (24M4DBP) (ml / 100 g) to CTAB is 0.75 to 0.00. 92, a rubber composition containing carbon black having a ratio of CTAB to IA of 0.97 to 1.25 and a specific coloring amount TINT (%) ≧ −46.787 (24M4DBP / CTAB) +168 It describes the point that it is possible to achieve both low temperature and low heat generation. In Patent Document 3 below, a rubber composition containing carbon black in which the ratio of N ₂ SA to IA is 1.20 to 1.30 and the difference between N ₂ SA and CTAB is adjusted to 5 or less is It describes that both wear and low heat build-up can be achieved. Further, in Patent Document 4 below, carbon having a CTAB of 120 or more, a compressed DBP absorption amount of 90 (ml / 100 g) or more, and a pore volume of 25 to 30 nm in the pore volume between aggregates is 30 ml / 100 g or more. It describes that the rubber composition containing black can achieve both wear resistance and low heat build-up.

  However, as a result of intensive studies by the present inventor, it is difficult to accurately grasp the degree of pores on the surface of the carbon black aggregate only by optimizing each index of carbon black noted in the above document. found. The degree of pores on the surface of the carbon black aggregate has a great influence on the low heat buildup and wear resistance, so the carbon black used in the above document has a particularly low heat buildup and wear resistance in the rim strip. It was found that there is room for further improvement when trying to achieve both.

  Patent Document 5 below describes that, in a rubber composition for a tire rim strip, by improving a rubber component, fatigue resistance and set resistance are improved without impairing rim rubbing properties. However, as a result of intensive studies by the inventor, it has been found that there is little room for improvement in low heat build-up by simply improving the rubber component.

JP 2009-40904 A JP 2000-344945 A JP 2007-231179 A JP-A-2005-334063 JP 2006-56978 A

  The present invention has been made in view of the above circumstances, and its object is to maintain a low exothermic property and set resistance, and to improve rim rubbing and fatigue resistance in a well-balanced manner and to have excellent durability. An object of the present invention is to provide a rubber composition and a pneumatic tire.

  In order to solve the above-mentioned problems, the present inventors diligently studied a method for accurately grasping the degree of pores on the surface of the carbon black aggregate. As a result, in the carbon black in which the difference between the BET specific surface area (BET5) and the external specific surface area (STSA) is within a specific range, the degree of pores on the surface of the carbon black aggregate is low exothermic property and wear resistance. It has been found that it is particularly preferable for achieving both of these. Further, in addition to BET5 and STSA, dibutyl phthalate (DBP) absorption amount, iodine adsorption amount (IA), and Stokes diameter (Dst) of carbon black, which have been conventionally used as indicators of carbon black characteristics, and It has been found that a low heat buildup and wear resistance of the rim strip can be improved in a well-balanced manner by using a rubber composition containing carbon black that is optimal in relation to the Stokes diameter distribution (ΔD-50 (half width)). It was. The present invention has been made as a result of the above-described studies, and achieves the above-described object with the following configuration.

That is, the present invention is a rubber composition for a rim strip containing a rubber component and carbon black, wherein the carbon black satisfies the following (1) to (4):
(1) Dibutyl phthalate (DBP) absorption (ml / 100 g) is 90 to 180,
(2) The difference between the BET specific surface area (BET5) (m ² / g) and the external specific surface area (STSA) (m ² / g) is 5 ≦ (BET5) − (STSA) ≦ 12,
(3) The ratio between the Stokes diameter (Dst) of the carbon black and the Stokes diameter distribution (ΔD-50 (half-value width)) is 0.70 ≦ (ΔD-50) / (Dst) ≦ 1.10. 4) The ratio of BET specific surface area (BET5) (m ² / g) to iodine adsorption amount (IA) (mg / g) is 1.05 ≦ (BET5) / (IA) ≦ 1.35, at least the carbon The compounding amount of the reinforcing filler containing black is 50 to 90 parts by mass with respect to 100 parts by mass of the rubber component, and the ratio of the carbon black in the reinforcing filler is 70% by mass or more. And a rim strip rubber composition.

  Since the rubber composition for rim strip according to the present invention has a carbon black (1) dibutyl phthalate (DBP) absorption amount (ml / 100 g) of 90 to 180, low heat build-up and wear resistance are well balanced. It can be compatible. The DBP absorption amount is an index of the structure of the carbon black aggregate, and if the DBP absorption amount is below the range described in (1), the structure of the carbon black aggregate is too low, so that the rubber reinforcement is It tends to decrease and durability deteriorates. On the other hand, when the DBP absorption amount exceeds the range described in (1), the structure of the carbon black aggregate is too high, and thus the low heat build-up tends to deteriorate.

The rubber composition for a rim strip according to the present invention has a difference between (2) BET specific surface area (BET5) (m ² / g) and external specific surface area (STSA) (m ² / g) of carbon black, 5 ≦ (BET5) − (STSA) ≦ 12. Since the BET specific surface area (BET5) and the external specific surface area (STSA) are both indices related to the specific surface area calculated based on the nitrogen absorption amount, the difference between the two is calculated, so that the carbon black aggregate surface The degree of pores can be accurately grasped.

  Since rubber molecules cannot enter the pores on the surface of the carbon black aggregate, the more pores, the weaker the bond between carbon black and rubber molecules. In the present invention, since the relationship of (BET5)-(STSA) of carbon black satisfies the above (2), the degree of binding between carbon black and rubber molecules is optimized, and as a result, low heat buildup and wear resistance are achieved. Can be balanced in a balanced manner.

  In the rim strip rubber composition according to the present invention, (3) the ratio of the Stokes diameter (Dst) of carbon black to the Stokes diameter distribution (ΔD-50 (half width)) is 0.70 ≦ (ΔD− 50) / (Dst) ≦ 1.10, the low heat buildup and wear resistance can be improved in a well-balanced manner. When (ΔD-50) / (Dst) is less than the range described in (3), the low heat build-up tends to deteriorate. On the other hand, if (ΔD-50) / (Dst) exceeds the range described in (3), the wear resistance tends to deteriorate.

Furthermore, the rubber composition for a rim strip according to the present invention has a ratio of (4) BET specific surface area (BET5) (m ² / g) to iodine adsorption amount (IA) (mg / g) of carbon black of 1 Since .05.ltoreq. (BET5) / (IA) .ltoreq.1.35, the degree of binding between carbon black and rubber molecules is optimized, and low heat buildup and wear resistance can be improved in a well-balanced manner. (BET5) / (IA) is an index of the surface activity of the carbon black particles. When (BET5) / (IA) is below the range described in (4), the low heat build-up tends to deteriorate. is there. On the other hand, if (BET5) / (IA) exceeds the range described in (4), the wear resistance tends to deteriorate.

  In the rubber composition for a rim strip according to the present invention, the amount of the reinforcing filler containing at least the carbon black is 50 to 90 parts by mass with respect to 100 parts by mass of the rubber component, and the reinforcing filler The ratio of the carbon black is set to 70% by mass or more. By setting the blending amount of the reinforcing filler containing carbon black within such a range, low heat build-up and wear resistance can be improved in a balanced manner.

In the rim strip rubber composition, the carbon black preferably has an external specific surface area (STSA) (m ² / g) of 75 to 170. STSA is an index of the specific surface area (particle size) of carbon black particles. When STSA is less than 75, wear resistance tends to deteriorate, and when it exceeds 170, low heat build-up tends to deteriorate. is there.

  In the rim strip rubber composition, it is preferable that 20 to 80 parts by mass of at least one of natural rubber and polyisoprene rubber and 20 to 80 parts by mass of polybutadiene rubber are contained in 100 parts by mass of the rubber component. The antiaging agent is preferably contained in an amount of 2 to 5 parts by mass with respect to 100 parts by mass of the rubber component. According to these structures, low heat build-up and wear resistance can be particularly well balanced.

  The present invention also relates to a pneumatic tire using the rim strip rubber composition described above as a rim strip. As described above, the vulcanized rubber of the rim strip rubber composition according to the present invention has improved low heat build-up and set resistance, and improved rim rub (abrasion resistance) and fatigue resistance in a well-balanced manner. Yes. Therefore, a pneumatic tire including a rim strip manufactured using such a rubber composition as a raw material is excellent in durability.

Tire meridian cross-sectional view showing an example of a pneumatic tire according to the present invention For each carbon black, a graph in which (BET5) / (IA) is plotted on the horizontal axis and (BET5)-(STSA) is plotted on the vertical axis.

  The rubber composition for rim strips according to the present invention contains a rubber component and carbon black. In the present invention, it is preferable to contain a diene rubber as a rubber component.

  Examples of the diene rubber include natural rubber (NR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), butadiene rubber (SPB) containing syndiotactic-1,2-polybutadiene, A chloroprene rubber (CR), a nitrile rubber (NBR), etc. are mentioned, These can each be used individually or as a 2 or more types of blend. These exemplified diene rubbers are those having terminal modified as required (for example, terminal modified BR, terminal modified SBR, etc.), or modified to give desired characteristics (for example, modified). NR) can also be used. Regarding polybutadiene rubber (BR), in addition to those synthesized using a cobalt (Co) catalyst, a neodymium (Nd) catalyst, a nickel (Ni) catalyst, a titanium (Ti) catalyst, and a lithium (Li) catalyst, WO2007 What was synthesize | combined using the polymerization catalyst composition containing the metallocene complex as described in -129670 can also be used. In order to improve the low heat buildup and wear resistance of the vulcanized rubber in a well-balanced manner, among the diene rubber, 20 to 80 mass of at least one of natural rubber and polyisoprene rubber in 100 mass parts of the rubber component. It is preferable to contain 20 to 80 parts by mass of polybutadiene rubber, more preferably 30 to 60 parts by mass of at least one of natural rubber and polyisoprene rubber, and 40 to 70 parts by mass of polybutadiene rubber.

In the present invention, the greatest feature is that the carbon black to be used satisfies the following (1) to (4).
(1) Dibutyl phthalate (DBP) absorption (ml / 100 g) is 90 to 180,
(2) The difference between the BET specific surface area (BET5) (m ² / g) and the external specific surface area (STSA) (m ² / g) is 5 ≦ (BET5) − (STSA) ≦ 12,
(3) The ratio between the Stokes diameter (Dst) of the carbon black and the Stokes diameter distribution (ΔD-50 (half-value width)) is 0.70 ≦ (ΔD-50) / (Dst) ≦ 1.10. 4) The ratio of the BET specific surface area (BET5) (m ² / g) to the iodine adsorption amount (IA) (mg / g) is 1.05 ≦ (BET5) / (IA) ≦ 1.35.

  The carbon black satisfying the above (1) to (4) has a smaller degree of pores on the surface of the carbon black aggregate than the ISAF class (ASTM grade) carbon black usually used in the tire industry. The carbon black has a special aggregate distribution. In the present invention, by using such a rubber composition containing carbon black as a raw material, low heat build-up and set resistance are improved, and rim rubbing (wear resistance) and fatigue resistance are improved in a well-balanced manner. Is done. More specifically, it achieves wear resistance and fatigue resistance comparable to rubber compositions containing ISAF class carbon black and low heat build-up comparable to rubber compositions containing HAF class carbon black. be able to.

The rubber composition for a rim strip according to the present invention preferably contains carbon black having an external specific surface area (STSA) (m ² / g) of 75 to 170. In this case, both wear resistance and low heat generation can be achieved in a balanced manner.

In particular, in the present invention, the carbon black dibutyl phthalate (DBP) absorption (ml / 100 g) is preferably 120 to 150, and the BET specific surface area (BET 5) (m ² / g) and the external specific surface area ( STSA) (m ² / g) is preferably 7 ≦ (BET5) − (STSA) ≦ 10, and the Stokes diameter (Dst) and Stokes diameter distribution (ΔD-50 (half width)) of carbon black )) Is preferably 0.75 ≦ (ΔD-50) / (Dst) ≦ 0.95, or the BET specific surface area (BET5) (m ² / g) and iodine adsorption amount (IA) ( mg / g) is preferably 1.10 ≦ (BET5) / (IA) ≦ 1.30. Moreover, in this invention, it is preferable that the external specific surface area (STSA) (m < ² > / g) of carbon black is 90-120.

Among the characteristic evaluation items of the carbon black, dibutyl phthalate (DBP) absorption (ml / 100 g) is JIS K6217-4, BET specific surface area (BET5) (m ² / g) and external specific surface area (STSA) (m ² / G) is JIS K6217-7, Stokes diameter (Dst) and Stokes diameter distribution (ΔD-50 (half-value width)) is JIS K6217-6, and iodine adsorption amount (IA) (mg / g) is JIS K6217-1. Measured according to the above.

  In the rubber composition for a rim strip according to the present invention, the compounding amount of the reinforcing filler containing carbon black satisfying the above (1) to (4) is 50 to 90 parts by mass with respect to 100 parts by mass of the rubber component. And the proportion of carbon black in the reinforcing filler is 70% by mass or more. In order to improve the wear resistance and the low heat build-up in a well-balanced manner, the blending amount of the reinforcing filler containing carbon black is preferably 55 to 85 parts by mass, and preferably 60 to 80 parts by mass. More preferably. Further, the proportion of carbon black in the reinforcing filler is more preferably 80% by mass or more.

  In the present invention, silica, calcium carbonate, magnesium carbonate, magnesium oxide, titanium oxide, talc, clay, alumina, sericite, or the like can be used as a filler other than carbon black. In addition, when using a silica, it is preferable to use a silane coupling agent together.

  In the present invention, it is preferable to contain an anti-aging agent in the rubber composition, in particular, in order to improve fatigue resistance. As an anti-aging agent, an aromatic amine-based anti-aging agent, an amine-ketone anti-aging agent, a monophenol anti-aging agent, a bisphenol anti-aging agent, a polyphenol anti-aging agent, dithiocarbamic acid, which are usually used for rubber Anti-aging agents such as a salt-based anti-aging agent and a thiourea-based anti-aging agent may be used alone or in an appropriate mixture. In consideration of rubber properties and durability, the blending amount of the anti-aging agent with respect to 100 parts by mass of the rubber component is preferably 2 to 5 parts by mass, and more preferably 2.5 to 4.5 parts by mass.

  The rubber composition according to the present invention includes the above rubber component, fillers such as carbon black and silica, and anti-aging agent, sulfur, silane coupling agent, zinc white, stearic acid, vulcanization accelerator, and vulcanization accelerator. Additives usually used in the rubber industry such as vulcanizing agents, vulcanization retarders, softeners such as waxes and oils, and processing aids can be appropriately mixed and used within a range not impairing the effects of the present invention.

  Sulfur should just be normal sulfur for rubber | gum, For example, powder sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur etc. can be used. When the rubber physical properties and durability after vulcanization are taken into consideration, the compounding amount of sulfur with respect to 100 parts by mass of the rubber component is preferably 0.1 to 5.0 parts by mass in terms of sulfur content, and 0.5 to 3.0. Part by mass is more preferable.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate. When the rubber physical properties and durability after vulcanization are taken into consideration, the blending amount of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 0.1 to 5 parts by mass.

  The rubber composition according to the present invention comprises the rubber component, fillers such as carbon black and silica, anti-aging agent, sulfur, silane coupling agent, zinc white, stearic acid, vulcanization accelerator, Additives usually used in the rubber industry such as vulcanization accelerators, vulcanization retarders, softeners such as wax and oil, and processing aids are used in the normal rubber industry such as Banbury mixers, kneaders and rolls. It can be obtained by kneading using a kneader.

  In addition, the blending method of each of the above components is not particularly limited, and a blending component other than a vulcanizing component such as sulfur and a vulcanization accelerator is previously kneaded to obtain a master batch, and the remaining components are added and further kneaded. , Rubber component and carbon black only in advance as a kneading masterbatch, the remaining components are added and further kneaded, each component is added in any order and kneaded, all components are added simultaneously and kneaded, etc. Either of these may be used. In addition, when making a rubber component and carbon black into a masterbatch beforehand, you may use the wet masterbatch obtained by mixing carbon black in rubber latex.

  As shown in FIG. 1, the pneumatic tire according to the present invention includes a pair of bead wires 1, a bead filler 2 disposed on the outer side of the bead wire 1 in the tire radial direction, a bead wire 1 and a bead filler 2. A sidewall 3 extending radially outward; a tread 4 connected to each tire radial outer end of the sidewall 3; and a carcass ply 5 whose ends are wound up from the inner side in the tire width direction by a pair of bead wires 1; And a belt 6 composed of a plurality of belt plies arranged on the outer peripheral side (outer in the tire radial direction) of the carcass ply 5. The tread 4 may be composed of a single rubber portion, or may be composed of two layers of a cap tread on the ground contact surface side and a base tread on the inner side in the tire radial direction.

  On the inner side in the tire radial direction of the bead wire 1 and the bead filler 2, a chacher 7 and a rim strip 8 are arranged via a carcass ply 5, and the rim strip 8 sits in contact with a tire rim (not shown). On the outer side of the bead filler 2 in the tire radial direction, a chacher pad 9 is disposed so as to sandwich the chacher 7. On the other hand, an inner liner 10 for maintaining air pressure is disposed on the inner peripheral side of the carcass ply 5. A shoulder pad 11 is disposed on the end side of the belt 6 in the tire radial direction, and a belt edge filler 12 is disposed between a plurality of belt ply end portions.

  Using the rubber composition according to the present invention, the rim strip 8 is manufactured by a known facility such as a rubber extruder, an unvulcanized tire including the rim strip 8 is molded, and then vulcanized according to a known method. Thus, it is possible to manufacture a pneumatic tire including a rim strip that has improved low heat buildup and set resistance, and improved rim rub resistance (wear resistance) and fatigue resistance in a well-balanced manner.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described. The evaluation items in Examples and the like were evaluated based on the following evaluation conditions for rubber samples obtained by heating and vulcanizing each rubber composition at 150 ° C. for 30 minutes.

(1) Rubber hardness According to JIS K6253, rubber hardness (durometer A type) at 23 ° C. is measured, and the measured value of Comparative Example 1 is indicated by index evaluation. The larger the value, the higher the rubber hardness and the better It means that.

(2) Breaking strength (breaking resistance)
In accordance with JIS K6251, a sample was prepared using dumbbell No. 3 and subjected to a tensile test, and the breaking strength at the time of breaking the sample was measured. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation. The larger the value, the better the fracture resistance.

(3) Bending fatigue resistance Bending fatigue resistance was evaluated according to JIS K6260. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation, and the larger the value, the better.

(4) Low exothermic property (tan δ)
Evaluation was performed based on tan δ values measured at an initial strain of 15%, a dynamic strain of ± 2.5%, a frequency of 10 Hz, and a temperature of 60 ° C. using a viscoelastic spectrometer manufactured by UBM. The measured value of Comparative Example 1 is indicated by index evaluation with 100, and the smaller the value, the better the low heat buildup.

(5) Abrasion resistance Abrasion resistance was evaluated by a pico abrasion test according to JIS K6264. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation, and the larger the value, the better.

(6) Set resistance The set resistance was evaluated by a permanent strain test (index of 1 / Cs) based on JIS K6262. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation, and the larger the value, the better.

(Preparation of rubber composition)
In accordance with the formulation of Table 1, the rubber compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were blended and kneaded using a normal Banbury mixer to prepare a rubber composition. Each compounding agent described in Table 1 is shown below (in Table 1, the compounding amounts of carbon black and each compounding agent are shown in terms of parts by mass with respect to 100 parts by mass of the rubber component). Carbon black was produced by the following production method.

a) Rubber component
Natural rubber (NR) "RSS # 3"
Polybutadiene rubber (BR) "BR01" (manufactured by JSR)
b) Zinc Hana “Zinc Hana 1” (Mitsui Mining & Mining Co., Ltd.)
c) Anti-aging agent “Sant Flex 6PPD” (manufactured by Flexis)
d) Sulfur (made by Shikoku Chemicals)
e) Vulcanization accelerator "Sunseller CM (CBS)"
f) Silica “Nipseal AQ” (made by Nippon Silica Kogyo Co., Ltd.)
g) Wax (Nippon Seiwa Co., Ltd.)
h) Stearic acid (manufactured by NOF Corporation)

(Method for producing carbon black)
A combustion chamber having a tangential air supply port at the furnace head and a combustion burner mounted in the furnace axis direction, a multistage narrow-diameter reaction chamber having a feed oil injection nozzle coaxially connected to the combustion chamber, and a wide chamber The carbon black mixed gas temperature is 1000 to 2200 ° C., and the ratio of the air amount (Nm ³ / h) to the raw material introduction amount (kg / h) is 2.0 using an oil furnace having a diameter reaction chamber. ~ 6.0, the ratio of the air amount and the fuel introduction amount (kg / h) is appropriately adjusted within the range of 15.0 to 30.0, and the ratio of the raw material introduction amount and the fuel introduction amount is within the range of 3.0 to 8.0. In order to obtain carbon black having a specified specific surface area, structure, surface activity, aggregate distribution, and degree of pores, the following i) to iv):
i) Split introduction of feedstock,
ii) oxygen gas addition,
iii) reaction time 0.002 to 0.05 (seconds),
iv) Drying temperature 180-250 (° C),
Were used alone or in combination to produce carbon blacks (A) to (E) shown in Table 1. Table 2 shows the carbon black characteristics of the carbon blacks (A) to (E). Moreover, about carbon black (A)-(E), the graph which plotted (BET5) / (IA) on the horizontal axis and (BET5)-(STSA) on the vertical axis | shaft is shown in FIG.

Moreover, the carbon black commercial item as described below was used as carbon black (F)-(G). Table 2 shows the carbon black characteristics of carbon blacks (F) to (G). Moreover, about carbon black (F)-(G), the graph which plotted (BET5) / (IA) on the horizontal axis and (BET5)-(STSA) on the vertical axis | shaft is shown in FIG.
i) Carbon Black (F) “Seast 300 (HAF-LS)” manufactured by Tokai Carbon Corporation j) Carbon Black (G) “Seast 3 (HAF)” manufactured by Tokai Carbon Corporation

  From the results of Table 1, in Examples 1 to 6 containing any one of carbon blacks (A) to (E), the low heat build-up property and the set resistance were improved, and the rim rubbing property (wear resistance) and It can be seen that the fatigue is improved in a well-balanced manner. On the other hand, in Comparative Examples 1 and 2 containing carbon black (F) or (G), the carbon black used does not satisfy any of the above conditions (1) to (4). It turns out that it deteriorates in any of a property, abrasion resistance, and fatigue resistance. In Comparative Example 3, which contains carbon black (A) but its content is low, the wear resistance and set resistance deteriorate, and in Comparative Example 4 where the content of carbon black (A) is high, low heat generation occurs. It can be seen that the resistance and fatigue resistance deteriorate.

Claims (5)

A rubber composition for a rim strip containing a rubber component and carbon black,
The carbon black satisfies the following (1) to (4),
(1) Dibutyl phthalate (DBP) absorption (ml / 100 g) is 90 to 180,
(2) The difference between the BET specific surface area (BET5) (m ² / g) and the external specific surface area (STSA) (m ² / g) is 5 ≦ (BET5) − (STSA) ≦ 12,
(3) The ratio between the Stokes diameter (Dst) of the carbon black and the Stokes diameter distribution (ΔD-50 (half-value width)) is 0.70 ≦ (ΔD-50) / (Dst) ≦ 1.10. 4) The ratio of the BET specific surface area (BET5) (m ² / g) to the iodine adsorption amount (IA) (mg / g) is 1.05 ≦ (BET5) / (IA) ≦ 1.35,
The amount of the reinforcing filler containing at least the carbon black is 50 to 90 parts by mass with respect to 100 parts by mass of the rubber component, and the proportion of the carbon black in the reinforcing filler is 70% by mass or more. A rubber composition for a rim strip, characterized in that The rubber composition for a rim strip according to claim 1, wherein the carbon black has an external specific surface area (STSA) (m ² / g) of 75 to 170.   The rubber composition for a rim strip according to claim 1 or 2, wherein 20 to 80 parts by mass of at least one of natural rubber and polyisoprene rubber and 20 to 80 parts by mass of polybutadiene rubber are contained in 100 parts by mass of the rubber component. .   The rubber composition for rim strips according to any one of claims 1 to 3, comprising 2 to 5 parts by mass of an anti-aging agent with respect to 100 parts by mass of the rubber component.   The pneumatic tire which used the rubber composition for rim strips in any one of Claims 1-4 for the rim strip.

Images