JP2012180450A - Rubber composition for squeegee and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a squeegee, serving as a raw material for a squeegee having fracture resistance and tear resistant strength improved in a well-balanced state while maintaining low heat buildup property; and to provide a pneumatic tire.SOLUTION: The rubber composition for a squeegee contains a carbon black satisfying the following (1) to (4): (1) dibutyl phthalate (DBP) absorbed amount (ml/100 g) is 90-180; (2) the difference between BET specific surface area (BET5) (m/g) and outer specific surface area (STSA) (m/g) is 5≤(BET5)-(STSA)≤12; (3) the ratio between Stokes diameter (Dst) and Stokes diameter distribution (ΔD-50 (half value width)) of the carbon black is 0.70≤(ΔD-50)/(Dst)≤1.10; and (4) the ratio between BET specific surface area (BET5) (m/g) and iodine adsorbed amount (IA) (mg/g) is 1.05≤(BET5)/(IA)≤1.35.

Description

  The present invention is a rubber composition for a squeegee that contains a rubber component and carbon black and is useful as a raw material for a squeegee for a pneumatic tire, and has a balance between fracture resistance and tear resistance while maintaining low heat buildup. The present invention relates to a rubber composition for a squeegee and a pneumatic tire as a raw material for a squeegee that is well improved.

  As shown in FIG. 1, a pneumatic tire generally includes a pair of bead wires 1, a bead filler 2 disposed on the outer side in the tire radial direction of the bead wire 1, and an outer side in the tire radial direction from the bead wire 1 and the bead filler 2. A side wall 3 extending in the tire width direction, a tread 4 connected to each tire radial direction outer end of each side wall 3, a carcass ply 5 having a pair of bead wires 1 whose end portions are wound outward from the inner side in the tire width direction, and a carcass ply 5 and a belt 6 composed of a plurality of belt plies arranged on the outer peripheral side (outer side in the tire radial direction). An inner liner 10 for maintaining air pressure is disposed on the inner peripheral side of the carcass ply 5.

  The inner liner is usually formed from halogenated butyl rubber, which has a low gas permeability, in order to maintain air pressure, but the carcass ply ply cord located on the outer peripheral side is used as the inner cord during tire molding and vulcanization. It may be exposed on the liner side. When the ply cord is exposed on the inner liner side, the rubber thickness between the inner liner and the ply cord becomes thin, and not only can the tire pressure not be maintained for a long period of time, but also the stress concentration is concentrated on the ply cord exposed when the tire rolls. May occur and tire durability may deteriorate.

  As a method for preventing the ply cord from being exposed to the inner liner side, there is a method in which a rubber sheet called a squeegee is interposed between the inner liner and the carcass ply. Such a squeegee is required to improve the fracture resistance and tear resistance in a well-balanced manner while maintaining low heat build-up. On the other hand, if the green modulus of the rubber composition that is the raw material of the squeegee is low, the rubber composition flows more than necessary during the vulcanization process, and the rubber thickness of the squeegee cannot be secured sufficiently. In some cases, the ply cord is exposed to the inner liner side. Therefore, it is necessary to increase the green modulus of the rubber composition that is the raw material for the squeegee.

  As a method for increasing the green modulus of the rubber composition, there is a method for increasing the content of carbon black in the rubber composition. However, when the carbon black content is increased, the low exothermic property of the squeegee after vulcanization tends to deteriorate. Therefore, it was difficult to improve the fracture resistance and tear strength in a well-balanced manner while maintaining low heat build-up, and to increase the green modulus of the rubber composition.

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, and 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. In addition, it describes that it is possible to achieve both fracture resistance and low heat build-up. 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 in which the ratio of CTAB to IA is 0.97 to 1.25 and the specific coloring amount TINT (%) ≧ −46.787 (24M4DBP / CTAB) +168 is It describes that both characteristics and low heat build-up can be achieved. 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 fracture characteristics and low heat build-up can be achieved.

  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 agglomerate has a great influence on the low heat buildup and fracture resistance, so the carbon black used in the above document has a particularly low heat buildup and fracture resistance in squeegees. It was found that there is room for further improvement when trying to achieve both.

  In Patent Document 4 below, the melting point is in the range of 60 to 110 ° C. with respect to 100 parts by weight of rubber containing natural rubber and / or isoprene rubber for the purpose of increasing the green modulus of the rubber composition used as the raw material for the squeegee. A method of blending 3 to 30 parts by weight of syndiotactic-1,2-polybutadiene is described. However, this document is characterized by focusing on the polymer component and optimizing the polymer component and its blending amount, and does not describe or suggest that the problem is solved by focusing on carbon black.

JP 2009-40904 A JP 2000-344945 A JP 2007-231179 A Japanese Patent Laid-Open No. 6-87976

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a squeegee rubber composition and an air as a raw material for a squeegee that maintains a low exothermic property and has improved fracture resistance and tear resistance in a well-balanced manner. The purpose is to provide tires.

  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 fracture resistance. It has been found that it is particularly preferable in order to achieve both the tear resistance strength. 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 By producing a squeegee using a rubber composition containing carbon black that is optimal in relation to the Stokes diameter distribution (ΔD-50 (half-value width)), the squeegee's low heat buildup, fracture resistance, and tear resistance And found that can be improved in a balanced manner. 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 squeegee rubber composition 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 quantity of the reinforcing filler containing black is 40 to 80 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 40% by mass or more. The rubber composition for squeegees characterized by these.

  Since the rubber composition according to the present invention has a carbon black (1) dibutyl phthalate (DBP) absorption (ml / 100 g) of 90 to 180, it balances low heat buildup with fracture resistance and tear resistance. A good balance can be achieved. 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.

Further, the rubber composition according to the present invention has a difference between the carbon black (2) BET specific surface area (BET5) (m ² / g) and the external specific surface area (STSA) (m ² / g) of 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 (BET5)-(STSA) relationship of carbon black satisfies the above (2), the degree of linking between carbon black and rubber molecules is optimized. It is possible to balance the tear resistance with a good balance.

  In the 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) / Since (Dst) ≦ 1.10, it is possible to improve the low exothermic property, the fracture resistance and the tear strength 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, when (ΔD-50) / (Dst) exceeds the range described in (3), the fracture resistance and tear resistance tend to deteriorate.

Furthermore, in the rubber composition according to the present invention, the ratio of (4) BET specific surface area (BET5) (m ² / g) and iodine adsorption amount (IA) (mg / g) of carbon black is 1.05 ≦ Since (BET5) / (IA) ≦ 1.35, the degree of binding between carbon black and rubber molecules is optimized, and low heat buildup and fracture 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, when (BET5) / (IA) exceeds the range described in (4), the fracture resistance and tear resistance tend to deteriorate.

  In the rubber composition according to the present invention, the blending amount of the reinforcing filler containing at least the carbon black is 40 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and the reinforcing filler has the above-mentioned content. The ratio of carbon black is set to 40% by mass or more. By setting the blending amount of the reinforcing filler containing carbon black within such a range, it is possible to improve the low exothermic property, the fracture resistance, and the tear resistance in a balanced manner.

In the 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, the fracture resistance tends to deteriorate, and when it exceeds 170, low heat build-up tends to deteriorate. is there.

  Moreover, this invention relates to a pneumatic tire provided with the squeegee manufactured using the rubber composition for squeegees in any one of the said. As described above, the vulcanized rubber of the rubber composition according to the present invention has a good balance between low heat build-up, fracture resistance, and tear resistance. Therefore, a pneumatic tire including a squeegee manufactured using such a squeegee rubber composition as a raw material has excellent 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 squeegee 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, fracture resistance and fatigue resistance of the vulcanized rubber in a well-balanced manner, it is preferable to use natural rubber as a main component among the diene rubbers. Specifically, when the total amount of the rubber component is 100 parts by mass, the natural rubber is preferably contained in an amount of 50 parts by mass or more, more preferably 75 parts by mass or more. Is particularly preferably 100 parts by mass.

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, fracture resistance and tear resistance are improved in a well-balanced manner. More specifically, it achieves fracture resistance and tear 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 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, the fracture resistance and the low heat buildup 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 according to the present invention, the amount of the reinforcing filler containing carbon black satisfying the above (1) to (4) is 40 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and the reinforcement is performed. The proportion of carbon black in the filler for use is 40% by mass or more. In order to improve the low heat build-up, fracture resistance, and tear strength in a balanced manner, the blending amount of the reinforcing filler containing carbon black is preferably 40 to 70 parts by mass, More preferably, it is 60 parts by mass.

  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.

  The rubber composition according to the present invention includes sulfur, a silane coupling agent, zinc white, stearic acid, a vulcanization accelerator, a vulcanization accelerator, a vulcanization together with the rubber component, fillers such as carbon black and silica. A compounding agent usually used in the rubber industry such as a retarder, an anti-aging agent, a softening agent such as wax or oil, or a processing aid can be appropriately blended 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 1 to 10 parts by mass and more preferably 3 to 8 parts by mass in terms of sulfur content.

  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. In consideration of rubber physical properties and durability after vulcanization, the blending amount of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 0.2 to 3.0 parts by mass.

  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 physical properties and durability, the blending amount of the anti-aging agent with respect to 100 parts by mass of the rubber component is preferably 1 to 5 parts by mass.

  The rubber composition according to the present invention comprises the above rubber component, fillers such as carbon black and silica, and optionally sulfur, silane coupling agent, zinc white, stearic acid, vulcanization accelerator, and vulcanization accelerator. Additives usually used in the rubber industry such as vulcanization retarders, anti-aging agents, softeners such as waxes and oils, processing aids, etc. are used in the normal rubber industry such as Banbury mixers, kneaders, rolls, etc. 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 and on the inner side in the tire radial direction, and a belt edge filler 12 is disposed between the belt plies 6b and 6c.

  The squeegee manufactured using the rubber composition for a squeegee according to the present invention as a raw material is molded into an unvulcanized tire provided between the inner liner 10 and the carcass ply 5 and then vulcanized according to a known method. A pneumatic tire provided with a squeegee having improved fracture resistance and tear resistance in a well-balanced manner while maintaining exothermic properties can be produced. In order to prevent the rubber flow of the squeegee rubber composition at the time of non-vulcanization, the green modulus (100% deformation modulus; M100) is preferably 0.30 MPa or more. On the other hand, if the green modulus is too high, it may break at the joint when expanded at the time of molding the tire. In addition, although the thickness of a squeegee can be suitably selected according to the size of a pneumatic tire, about 0.3-2.0 mm is illustrated, for example.

  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) Existence of ply cord exposure (cord out) After molding an unvulcanized tire in which a squeegee is provided between the inner liner and the carcass ply, vulcanize it according to a known method. It was visually confirmed whether or not the inner surface was exposed (out of the cord). The case where code output occurred was evaluated as “Yes”, and the case where code output did not occur was evaluated as “None”.

(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. Larger values mean better fracture resistance.

(3) Tear resistance strength Tear strength (tear resistance) was evaluated according to JIS K6252. The larger the value, the better the tear resistance.

(4) Low exothermic property (tan δ)
The tan δ value at an initial strain of 10%, a dynamic strain of 2%, a frequency of 50 Hz, and a temperature of 60 ° C. was measured using a viscoelastic spectrometer manufactured by UBM. It means that it is excellent in low exothermic property, so that a numerical value is small.

(5) Green modulus of rubber composition An unvulcanized rubber composition is molded into a sheet with a roll, and subjected to a tensile test at room temperature in accordance with JIS K6251 (No. 3 dumbbell) to obtain 100% deformation modulus. It was measured. The larger the numerical value, the less rubber flows during vulcanization and the better the moldability.

(Preparation of rubber composition)
In accordance with the formulation of Table 1, the rubber compositions of Examples 1 to 7 and Comparative Examples 1 to 5 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) Natural rubber (NR) "RSS # 3"
b) Silica “Nipseal AQ” (manufactured by Nippon Silica Industry Co., Ltd.)
c) Zinc Hana “Zinc Hana 3” (Mitsui Mining & Mining Co., Ltd.)
d) Anti-aging agent “Sant Flex 6PPD” (manufactured by Flexis)
e) Vulcanization accelerator “Noxeller DZ-G” (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
f) Insoluble sulfur "Muclon HS OT-20" (manufactured by Flexis)

(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.
g) Carbon Black (F) “Seast 300 (HAF-LS)” manufactured by Tokai Carbon Co., Ltd. h) Carbon Black (G) “Seast 3 (HAF)” manufactured by Tokai Carbon Co., Ltd.

  From the results of Table 1, it can be seen that in Examples 1 to 7 containing any of carbon blacks (A) to (E), the low heat build-up property, the fracture resistance and the tear resistance are improved in a well-balanced manner. On the other hand, in Comparative Examples 1 to 3 containing carbon black (F) or (G), the carbon black used does not satisfy any of the above conditions (1) to (4). It can be seen that either the properties or the tear strength deteriorates. In Comparative Example 4, which contains carbon black (A) but its content is low, the fracture resistance is deteriorated, and in Comparative Example 5 where the content of carbon black (A) is high, the low heat build-up property is deteriorated. I understand that.

Claims (3)

A rubber composition for a squeegee 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 40 to 80 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 40% by mass or more. A rubber composition for squeegee, which is characterized by the above. ^{2. The} rubber composition for squeegee according to claim 1, wherein the carbon black has an external specific surface area (STSA) (m ² / g) of 75 to 170. 3.   A pneumatic tire provided with the squeegee manufactured using the rubber composition for squeegees of Claim 1 or 2.

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