JP2013006895A - Rubber composition, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a chafer pad, improved well balancedly in breaking resistance, fatigue resistance and cut resistance while maintaining low heat buildup, and to provide a pneumatic tire.SOLUTION: The rubber composition for a chafer pad contains at least a rubber component and an inorganic filler. The inorganic filler has an angle of repose of ≥40°, a Mohs' hardness of ≤2.0, a BET specific surface area (BET5)(m/g) of ≥10 m/g, and a ratio (DBP)/(BET5) of an absorbing amount (ml/100 g) of dibutyl phthalate (DBP) and the BET specific surface area (BET5)(m/g) of ≥2.0. The content of the inorganic filler is 3 to 30 pts.mass based on 100 pts.mass of the rubber component.

Description

  The present invention relates to a rubber composition for a chacher pad and a pneumatic tire containing at least a rubber component and an inorganic filler, and balances fracture resistance, fatigue resistance, and cut resistance while maintaining low heat generation. The present invention relates to a rubber composition for a cheerpad that is well improved and a pneumatic tire.

  As shown in FIG. 2, the bead filler 102 disposed on the outer side in the tire radial direction of the bead wire 101 and the chacher pad 109 disposed on the outer side in the tire radial direction of the bead filler 102 are members disposed inside the tire. Therefore, it is easy to store heat during tire travel. For this reason, considering durability, it is indispensable for the bead filler and the chacher pad to reduce the heat generation of the rubber itself.

  As a general method for improving the low exothermic property of rubber, there is a method of reducing the amount of carbon black compounded in rubber as a reinforcing material. However, when the amount of carbon black is reduced, the fracture resistance and elastic modulus of the rubber are lowered, and the amount of deformation during tire running increases. For this reason, the fatigue deterioration of rubber tends to proceed, and as a result, the durability of the pneumatic tire tends to deteriorate. In addition, with regard to the chapad, as a general method for improving the bead durability, a method of blending an adhesive resin such as a methylene acceptor such as resorcin, a methylene donor such as hexamethylenetetramine, which forms strong adhesion There is. However, when such an adhesive resin is blended in a large amount, the fracture resistance of the rubber decreases, and as a result, the durability of the pneumatic tire tends to deteriorate. Therefore, especially in the case of a chacher pad, it is strongly required to improve the fracture resistance and fatigue resistance in a well-balanced manner while maintaining low heat generation.

  In the following Patent Document 1, in the vulcanized rubber of the rubber composition for an inner liner of a tire, in order to improve tear strength and fatigue resistance while maintaining good airtightness, in the rubber composition, A method of blending talc with a high flatness together with predetermined carbon black is described. However, in this method, the airtightness is improved, but the fracture resistance, fatigue resistance and cut resistance are insufficiently improved, and there is room for further improvement in this respect.

Special table 2008-528739 gazette

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber composition for a chacher pad in which fracture resistance, fatigue resistance, and cut resistance are improved in a well-balanced manner while maintaining low heat generation. And providing a pneumatic tire.

The above object can be achieved by the present invention as described below. That is, the rubber composition for a chacher pad according to the present invention is a rubber composition for a chacher pad containing at least a rubber component and an inorganic filler, and the inorganic filler has an angle of repose of 40 degrees or more, Mohs hardness is 2.0 or less, BET specific surface area (BET5) (m ² / g) is 10 m ² / g or more, and dibutyl phthalate (DBP) absorption (ml / 100 g) and BET specific surface area (BET5) (m ² / G) (DBP) / (BET5) is 2.0 or more, and the content of the inorganic filler with respect to 100 parts by mass of the rubber component is 3 to 30 parts by mass.

  According to the rubber composition, the inorganic filling having a specific flatness (angle of repose), specific specific surface area (BET5), specific structure development ((DBP) / (BET5)), and specific Mohs hardness Since the material contains 3 to 30 parts by mass, the rubber properties of the vulcanized rubber are well maintained, and the fracture resistance, fatigue resistance and cut resistance are improved in a well-balanced manner, and low heat build-up is improved.

  In the rubber composition, the inorganic filler is preferably talc. According to such a configuration, the fracture resistance, fatigue resistance, cut resistance, and low heat buildup of the vulcanized rubber are improved in a balanced manner. Further, talc is a natural mineral and is low in cost, and is preferable from both the environmental and cost aspects.

  The rubber composition preferably further contains a reinforcing filler composed of at least one of carbon black and silica, and the content of the inorganic filler is preferably smaller than the content of the reinforcing filler. The rubber composition contains a reinforcing filler composed of at least one of carbon black and silica, together with an inorganic filler having a specific flatness, a specific DBP absorption amount, a specific specific surface area, and a specific Mohs hardness. In this case, due to the influence of the inorganic filler, the dispersibility of the reinforcing filler in the rubber composition is improved as compared with the case where the reinforcing filler is contained alone. For this reason, the fracture resistance, fatigue resistance, cut resistance, and low heat build-up of vulcanized rubber are particularly improved in a well-balanced manner. The reason why the dispersibility of the reinforcing filler is improved when used in combination with the inorganic filler is not clear, but when the inorganic filler and the reinforcing filler are kneaded together with the rubber component, the inorganic filler is Since it slips in the polymer, it can be considered that it functions to assist the dispersion of the reinforcing filler in the polymer. In order to improve the fracture resistance, fatigue resistance, cut resistance, and low heat buildup of the vulcanized rubber in a well-balanced manner while maintaining the processability of the rubber composition, the content of the reinforcing filler is: It is preferable that it is 30-70 mass parts with respect to 100 mass parts of said rubber components, and the compounding quantity of reinforcing fillers other than said carbon black is 0-10 mass parts with respect to 100 mass parts of said rubber components. It is more preferable.

  The pneumatic tire according to the present invention is obtained by using any one of the rubber compositions described above for a cheer pad. In such a pneumatic tire, rubber properties, fracture resistance, fatigue resistance, cut resistance, and low heat build-up are improved in a well-balanced manner.

Side view showing instrument and method for measuring angle of repose and height (H) of inorganic filler Tire meridian cross-sectional view showing an example of a pneumatic tire according to the present invention

  The rubber composition according to the present invention contains at least a rubber component and an inorganic filler. 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 addition to the rubber component, the rubber composition according to the present invention has an angle of repose of 40 degrees or more, a Mohs hardness of 2.0 or less, a BET specific surface area (BET5) of 10 m ² / g or more, and dibutyl phthalate (DBP) absorption. It contains an inorganic filler having a ratio (DBP) / (BET5) of 2.0 or more between the amount (ml / 100 g) and the BET specific surface area (BET5) (m ² / g). When the angle of repose of the inorganic filler is less than 40 degrees, the flatness is too high or the particle diameter is too large, so the fracture resistance, fatigue resistance and cut resistance of the vulcanized rubber are lowered. On the other hand, when the Mohs hardness of the inorganic filler exceeds 2, it causes a decrease in dispersibility in rubber and concentration of stress, which deteriorates fracture resistance, fatigue resistance, cut resistance, and low heat buildup. Furthermore, when (DBP) / (BET5) is less than 2, a sufficient reinforcing effect cannot be obtained, and the elastic modulus decreases. In order to improve the fracture resistance, fatigue resistance, cut resistance, and low heat buildup of the vulcanized rubber in a well-balanced manner, the angle of repose is 42 degrees or more, the Mohs hardness is 1 or less, the BET 5 is 10 m ² / g or more, And / or (DBP) / (BET5) is preferably 3.0 or more. The upper limit of the angle of repose is 50 degrees or less, the upper limit of BET5 is 30 m ² / g or less, and / or the upper limit of (DBP) / (BET5) is 10 or less.

  The angle of repose of the inorganic filler can be measured by the following method.

(Apparatus and method for measuring angle of repose and height (H) of inorganic filler)
As shown in FIG. 1, a 10 g powder sample 1, a tempered glass funnel 2 (bore diameter 45 mm, leg inner diameter 5 mm, total length 90 mm, leg length 45 mm), funnel mount 3 that supports and fixes the funnel 2, and the funnel A rubber stopper is used to block the discharge port 21 at the lower end of the leg 2. The height from the horizontal base plate 4 to the discharge port 21 of the funnel 2 is adjusted to 4 cm by adjusting the height of the funnel mount 3. A 10 g powder sample is poured into a glass funnel with the outlet 21 of the funnel 2 closed with a rubber stopper, and then the rubber stopper is gently pulled out. After confirming that the powder sample 1 has formed a substantially accurate cone-shaped peak on the horizontal base plate 4, the height (H) and diameter (D) of this cone-shaped peak are measured. Further, based on this measurement, the following formula (1):
tan (angle of repose) = H / (D / 2) (1)
To find the angle of repose.

  The inorganic filler used in the present invention has a higher degree of flatness (high flatness) as the angle of repose measured by the above method is smaller. When an inorganic filler having a high flatness is blended in the rubber composition, the fracture resistance, fatigue resistance and cut resistance are particularly deteriorated. Similarly, the lower the height (H) measured by the above method, the higher the flatness of the inorganic filler (higher flatness). For this reason, when a low-flat inorganic filler having a height (H) measured by the above method of 30 mm or more is blended in the rubber composition, in particular, the fracture resistance, fatigue resistance and resistance to vulcanized rubber. This is preferable because the cutting property is improved.

  Content of the inorganic filler in the rubber composition which concerns on this invention is set to 3-30 mass parts with respect to 100 mass parts of rubber components. By setting the content of the inorganic filler within this range, the elastic modulus, tear resistance, fatigue resistance and low heat build-up of the vulcanized rubber can be improved in a well-balanced manner. In order to improve the physical properties of the vulcanized rubber with better balance, the content of the inorganic filler with respect to 100 parts by mass of the rubber component is preferably 3 to 15 parts by mass.

  An example of the inorganic filler is talc. When talc is used as an inorganic filler, the fracture resistance, tear resistance and low heat buildup of vulcanized rubber are improved in a well-balanced manner.

Talc is an inorganic powder obtained by pulverizing an ore called natural talc, and contains hydrous magnesium silicate [Mg ₃ Si ₄ O ₁₀ (OH) ₂ ] as a main component. In the present invention, commercially available talc can also be used preferably. For example, “MISTOR VAPOR RE” (Mittron VAPOR RE, manufactured by Nippon Mytron Co., Ltd., angle of repose 44 °, Mohs hardness 1, (BET5) 13.4 m ² / g, (DBP ) / (BET5) 3.7), “P-6” manufactured by Nippon Talc Co., Ltd. (repose angle 44 degrees, Mohs hardness 1, (BET5) 10.5 m ² / g, (DBP) / (BET5) 4.3) Etc.) can be suitably used.

  In the present invention, at least one of carbon black and silica is used as the reinforcing filler. As carbon black, for example, conductive carbon black such as acetylene black and ketjen black can be used in addition to carbon black used in ordinary rubber industry such as SAF, ISAF, HAF, FEF, and GPF. Examples of the silica include wet silica, dry silica, colloidal silica, precipitated silica, and the like. It is particularly preferable to use wet silica containing hydrous silicic acid as a main component. In order to maintain the processability of the rubber composition and improve the fracture resistance, tear resistance and low heat buildup of the vulcanized rubber in a well-balanced manner, the content of the inorganic filler is greater than the content of the reinforcing filler. Further, the content of the reinforcing filler is more preferably 30 to 70 parts by mass, particularly preferably 40 to 60 parts by mass with respect to 100 parts by mass of the rubber component.

  In the rubber composition according to the present invention, a methylene acceptor and a methylene donor may be blended in order to improve the adhesion with the carcass ply, the chacher, and the sidewall. Adhesiveness with the carcass ply, the chacher, and the sidewall can be enhanced by the curing reaction between the hydroxyl group of the methylene acceptor and the methylene group of the methylene donor.

  As the methylene acceptor, a phenolic compound or a phenolic resin obtained by condensing a phenolic compound with formaldehyde is used. Such phenolic compounds include phenol, resorcin or alkyl derivatives thereof. Alkyl derivatives include methyl group derivatives such as cresol and xylenol, and derivatives with long chain alkyl groups such as nonylphenol and octylphenol. The phenol compound may contain an acyl group such as an acetyl group as a substituent.

  In addition, phenolic resins obtained by condensing phenolic compounds with formaldehyde include resorcin-formaldehyde resins, phenolic resins (phenol-formaldehyde resins), cresol resins (cresol-formaldehyde resins), and formaldehyde composed of a plurality of phenolic compounds. Resin etc. are included. These are uncured resins that have liquid or heat fluidity.

  Among these, from the viewpoint of compatibility with the rubber component and other components, the density of the resin after curing, and the reliability, the methylene acceptor is preferably resorcin or a resorcin derivative, and in particular, resorcin or resorcin Alkylphenol-formalin resins are preferred. As a compounding quantity of these phenol compounds or phenol-type resin, it is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of rubber components, More preferably, it is 0.5-5 mass parts.

  As the methylene donor, hexamethylenetetramine or a melamine derivative is used. As such a melamine derivative, for example, methylol melamine, a partially etherified product of methylol melamine, a condensate of melamine, formaldehyde, and methanol is used, and among them, hexamethoxymethyl melamine is particularly preferable. As a compounding quantity of a hexamethylenetetramine or a melamine derivative, it is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of rubber components, More preferably, it is 0.5-5 mass parts.

  The rubber composition according to the present invention includes the above rubber component, inorganic filler, reinforcing filler, methylene acceptor and methylene donor, sulfur, silane coupling agent, zinc white, stearic acid, vulcanization accelerator, Compounding agents usually used in the rubber industry, such as vulcanization accelerators, vulcanization retarders, anti-aging agents, softeners such as waxes and oils, and processing aids, are blended appropriately within a range that does not impair the effects of the present invention. Can be used.

  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 2 to 8 parts by mass, more preferably 3 to 7 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. 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.

  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 0.1 to 5 parts by mass.

  The rubber composition according to the present invention comprises the above rubber component, inorganic filler, reinforcing filler, if necessary, methylene acceptor and methylene donor, sulfur, silane coupling agent, zinc white, stearic acid, vulcanization Additives usually used in the rubber industry such as accelerators, vulcanization accelerators, vulcanization retarders, anti-aging agents, softeners such as waxes and oils, and processing aids, such as Banbury mixers, kneaders, rolls, etc. It can be obtained by kneading using a kneader used in a normal rubber industry.

  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. 2, the pneumatic tire according to the present invention includes a pair of bead wires 101, a bead filler 102 disposed on the outer side in the tire radial direction of the bead wires 101, and a bead wire 101 and a bead filler 102. A sidewall 103 extending radially outward; a tread 104 connected to each tire radial outer end of the sidewall 103; and a carcass ply 105 having a pair of bead wires 101 wound up from the inner side to the outer side in the tire width direction; And a belt 106 made of a plurality of belt plies arranged on the outer peripheral side (outer side in the tire radial direction) of the carcass ply 105. In the example shown in FIG. 2, the bead filler 102 has a two-layer structure of an upper bead filler 102 a and a lower bead filler 102 b that is harder than the bead filler 102 a and is in contact with the bead wire 101.

  On the inner side in the tire radial direction of the bead wire 101 and the bead filler 102, a chacher 107 and a rim strip 108 are arranged via a carcass ply 105, and the rim strip 108 is seated so as to be in contact with a tire rim (not shown). On the outer side of the bead filler 102 in the tire radial direction, a chacher pad 109 is disposed so as to sandwich the chacher 107. On the other hand, an inner liner 110 for maintaining air pressure is disposed on the inner peripheral side of the carcass ply 105. Further, a shoulder pad 111 is disposed on the end side of the belt 106 on the inner side in the tire radial direction, and a belt edge filler 112 is disposed between a plurality of belt ply end portions.

  Using the rubber composition according to the present invention, the chacher pad 109 is manufactured by a known facility such as a rubber extruder, an unvulcanized tire including the same is molded, and then vulcanized according to a known method. Accordingly, it is possible to manufacture a pneumatic tire including a chacher pad that is improved in a balanced manner with respect to fracture resistance, fatigue resistance, and cut resistance while maintaining low heat generation.

  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 Based on JIS K6253, it evaluated by the rubber hardness (durometer A type) in 23 degreeC. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation. The larger the value, the higher the rubber hardness.

(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, and the larger the value, the better the fracture resistance.

(3) Tear strength (cut resistance)
Evaluation was performed in accordance with JIS K6252. The measured value of Comparative Example 1 is set to 100 and displayed by index evaluation, and the larger the value, the better the cut resistance.

(4) Fatigue resistance properties Evaluation was performed according to JIS K6260. On the basis of Comparative Example 1, the measurement values were evaluated as “◯ (good)” and those inferior as “× (poor)”.

(5) 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.

(Preparation of rubber composition)
In accordance with the formulation of Table 1, the rubber compositions of Examples 1 to 5 and Comparative Examples 1 to 8 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 amount of each compounding agent is shown in terms of parts by mass with respect to 100 parts by mass of the rubber component). In addition, the repose angle and height (H) of the following inorganic fillers (A) to (F) (the height (H) measured by the above-mentioned “method for measuring the repose angle and height (H) of the inorganic filler”) )), Specific surface area (BET5), structure development degree ((DBP) / (BET5)), and Mohs hardness are shown in Table 2.
a) Rubber component Natural rubber (NR) "RSS # 3"
b) Carbon Black (HAF) “Seast KH”, manufactured by Tokai Carbon Co., Ltd. c) Silica “Nip Seal AQ” (produced by Nippon Silica Kogyo Co., Ltd.)
d) Inorganic filler Inorganic filler (A) “MISTORON VAPOR RE”, manufactured by Nippon Mystron Co., Ltd. Inorganic filler (B) “P-6”, manufactured by Nippon Talc Co., Ltd. Inorganic filler (C) “SW”, Nippon Talc Co., Ltd. Inorganic filler (D) “HAR”, Nippon Mistron inorganic filler (E) “Shiraka Hana CC”, Shiraishi Kogyo inorganic filler (F) “Hard clay”, Shiraishi Kogyo e) Zinc Hana “ Zinc Hana 3 "(Mitsui Mining & Mining)
f) Anti-aging agent “Sant Flex 6PPD” (manufactured by Flexis)
g) Vulcanization accelerator “Noxeller NS-P” (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
h) Insoluble sulfur “Christex HS OT-20” (manufactured by Flexis)
i) Oil (made by Japan Energy)
j) Resorcin-alkylphenol-formalin resin “SUMIKANOL 620” (manufactured by Sumitomo Chemical Co., Ltd.)
k) Hexamethoxymethylmelamine “Cylettes 963L” (Mitsui Cytec)

  From the results of Table 1, it can be seen that in the vulcanized rubbers of the rubber compositions according to Examples 1 to 5, rubber properties, fracture resistance, cut resistance, fatigue resistance, and low heat build-up are improved in a well-balanced manner. On the other hand, in the rubber composition according to Comparative Example 2, since only the amount of carbon black was increased, the low heat buildup and fatigue resistance were deteriorated. Further, in the vulcanized rubber of the rubber composition according to Comparative Example 3, since the amount of talc is too small, there is an improvement effect in any of rubber properties, fracture resistance, cut resistance, fatigue resistance and low heat build-up. I couldn't see it. Moreover, in the vulcanized rubber of the rubber composition according to Comparative Example 4, since the amount of talc was too large, the low heat buildup and fatigue resistance were deteriorated. Further, in the vulcanized rubber of the rubber composition according to Comparative Example 5, since BET5 is small and large particle size talc is used, the fracture resistance and fatigue resistance are deteriorated, and in Comparative Example 6 where high flat talc is used. It can be seen that even the vulcanized rubber of such a rubber composition deteriorates the fracture resistance, cut resistance and fatigue resistance. Further, in the vulcanized rubber of the rubber composition according to Comparative Example 7, since calcium carbonate having a high Mohs hardness is used, it causes a decrease in dispersibility and stress concentration in the rubber, resulting in fracture resistance, cut resistance, The fatigue resistance and low heat build-up are deteriorated, and the vulcanized rubber of the rubber composition according to Comparative Example 8 uses a high-flat clay, so that the fracture resistance, cut resistance and fatigue resistance may be deteriorated. Recognize.

Claims (6)

A rubber composition for a chacher pad containing at least a rubber component and an inorganic filler,
The inorganic filler has an angle of repose of 40 degrees or more, a Mohs hardness of 2.0 or less, a BET specific surface area (BET5) (m ² / g) of 10 m ² / g or more, and a dibutyl phthalate (DBP) absorption amount ( ml / 100 g) and BET specific surface area (BET5) (m ² / g) (DBP) / (BET5) is 2.0 or more,
Content of the said inorganic filler with respect to 100 mass parts of said rubber components is 3-30 mass parts, The rubber composition for chaher pads characterized by the above-mentioned.   The rubber composition for a chacher pad according to claim 1, wherein the inorganic filler is talc.   The chacher pad according to claim 1, further comprising a reinforcing filler composed of at least one of carbon black and silica, wherein the content of the inorganic filler is smaller than the content of the reinforcing filler. Rubber composition.   The rubber composition for a chacher pad according to any one of claims 1 to 3, wherein a content of the reinforcing filler with respect to 100 parts by mass of the rubber component is 30 to 70 parts by mass.   The rubber composition according to any one of claims 1 to 4, wherein a compounding amount of the reinforcing filler other than the carbon black is 0 to 10 parts by mass with respect to 100 parts by mass of the rubber component.   A pneumatic tire using the rubber composition according to any one of claims 1 to 5 for a cheer pad.