JP2015218188A - Rubber composition for air spring, and air spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air spring having a high modulus and also satisfactory in bending fatigue resistance, and a rubber composition for an air spring used for the structural member of the air spring.SOLUTION: Provided is a rubber composition for an air spring including diene rubber and carbon black, in which the diene rubber includes modified butadiene rubber obtainable by modifying natural rubber and butadiene rubber with a nitrone compound, and the content of the modified butadiene rubber in the diene rubber is 15 to 60 mass%.

Description

  The present invention relates to a rubber composition for an air spring and an air spring.

  It is known that an air spring that is used for a pillow spring device of a railway vehicle, an air suspension of an automobile, and the like and that exhibits a buffer function is required to have high weather resistance because it is exposed to various usage environments.

  For the purpose of satisfying such required characteristics, for example, Patent Document 1 describes, “In a rubber composition for air springs containing a rubber component mainly composed of natural rubber and polybutadiene rubber, ethylene as the rubber component. · A rubber composition for an air spring characterized by containing 10 to 40 parts by weight of an α-olefin / diene copolymer rubber with respect to 100 parts by weight of the total rubber component. 1]).

  Patent Document 2 states that, “In a rubber composition for an air spring containing a rubber component mainly composed of natural rubber and polybutadiene rubber, polychloroprene rubber is further added as the rubber component to 100 parts by weight of the rubber component. 10 to 30 parts by weight of a rubber composition for air springs ”([Claim 1]).

  Patent Document 3 discloses that “a conjugated diene compound-nonconjugated olefin copolymer (A), a chloroprene rubber (B), and a nonconjugated diene compound-nonconjugated olefin copolymer containing ethylene-propylene-diene rubber”. A rubber composition for an air spring comprising (C), wherein the chloroprene rubber (B) is in the range of 60 to 80 parts by mass in 100 parts by mass of the rubber component. Rubber composition "is described ([Claim 1]).

  Patent Document 4 states that “in a rubber composition containing a rubber component, an amine-based anti-aging agent, and a wax, the blending amount of the amine-based anti-aging agent with respect to 100 parts by weight of the rubber component (A), When the blending amount of the wax is (B), 5.0 ≦ (B) ≦ 10.0 and 1.5 ≦ (A) / (B) ≦ 3.0, and the amine-based antioxidant The rubber composition characterized in that the blending amount (A) is 7.5 to 15 parts by weight. "[Claim 1]).

JP 2009-215541 A JP 2010-013504 A JP 2013-155296 A Japanese Patent No. 5393049

  The present inventors examined conventionally known rubber compositions for air springs described in Patent Documents 1 to 4 and the like. As a result, there is room for improvement in the modulus, and cracks due to repeated bending due to vibration are present. It was clarified that it may occur. In the present specification, the property of suppressing the occurrence of cracks due to bending is referred to as “bending fatigue resistance”.

  Therefore, an object of the present invention is to provide an air spring having a high modulus and good bending fatigue resistance, and a rubber composition for an air spring used for a constituent member of the air spring.

As a result of intensive studies on the above problems, the present inventors have used a rubber composition containing a specific amount of modified butadiene rubber obtained by modifying butadiene rubber with a nitrone compound, thereby having high modulus and bending resistance. The inventors have found that an air spring with good fatigue can be produced, and have reached the present invention.
That is, the present inventors have found that the above problem can be solved by the following configuration.

[1] containing a diene rubber and carbon black,
The diene rubber includes natural rubber and a modified butadiene rubber obtained by modifying a butadiene rubber with a nitrone compound,
A rubber composition for an air spring, wherein the content of the modified butadiene rubber in the diene rubber is 15 to 60% by mass.
[2] The rubber composition for an air spring according to [1], wherein the content of the carbon black is 30 to 60 parts by mass with respect to 100 parts by mass of the diene rubber.
[3] The rubber composition for an air spring according to [1] or [2], wherein the carbon black has a nitrogen adsorption specific surface area of 20 to 40 m ² / g.
[4] The nitrone compound is N-phenyl-α- (4-carboxyphenyl) nitrone, N-phenyl-α- (3-carboxyphenyl) nitrone, N-phenyl-α- (2-carboxyphenyl) nitrone, A compound selected from the group consisting of N- (4-carboxyphenyl) -α-phenylnitrone, N- (3-carboxyphenyl) -α-phenylnitrone and N- (2-carboxyphenyl) -α-phenylnitrone. The rubber composition for air springs according to any one of [1] to [3].
[5] The rubber composition for an air spring according to any one of [1] to [4], wherein the modified butadiene rubber has a modification rate of 0.02 to 4.0 mol%.
Here, the modification rate represents the ratio (mol%) modified by the nitrone compound among all the double bonds derived from the conjugated diene of the conjugated diene polymer.
[6] An air spring comprising a constituent member using the rubber composition for an air spring according to any one of [1] to [5].

  As described below, according to the present invention, it is possible to provide an air spring having a high modulus and good bending fatigue resistance, and a rubber composition for an air spring used for a component of the air spring. .

Below, the rubber composition for air springs of this invention and the air spring of this invention are demonstrated.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Rubber composition for air spring]
The rubber composition for an air spring of the present invention (hereinafter also referred to as “the rubber composition of the present invention”) contains a diene rubber and carbon black, and the diene rubber comprises natural rubber and butadiene rubber. And a modified butadiene rubber obtained by modifying a nitrone compound, and the content of the modified butadiene rubber in the diene rubber is 15 to 60% by mass.
Since the rubber composition of the present invention has such a configuration, when it is used as a component member of an air spring, a high modulus is exhibited and the bending fatigue resistance is also good. The reason is not clear, but it is presumed that it is as follows.

As described above, the rubber composition of the present invention contains a modified butadiene rubber obtained by modification with a nitrone compound.
The nitrone modification site in the modified butadiene rubber is presumed to be due to the formation of a strong three-dimensional structure between the rubber component and the carbon black due to the interaction (bonding) with the carbon black in the composition.
Hereinafter, each component contained in the rubber composition of the present invention will be described in detail.

[Diene rubber]
The diene rubber contained in the rubber composition of the present invention includes natural rubber and modified butadiene rubber obtained by modifying butadiene rubber with a nitrone compound. Here, the content of the modified butadiene rubber in the diene rubber is 15 to 60% by mass.
The diene rubber may contain a rubber component other than the natural rubber and the modified butadiene rubber. The rubber component is not particularly limited, but isoprene rubber (IR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber (for example, styrene butadiene rubber (SBR)), acrylonitrile-butadiene copolymer rubber. (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR) and the like. Of these, butadiene rubber (BR) and styrene butadiene rubber (SBR) are preferable.

<Natural rubber>
As described above, the diene rubber contained in the rubber composition of the present invention includes natural rubber.
The content of the natural rubber in the diene rubber is not particularly limited, but is preferably 20 to 80% by mass, more preferably 30 to 70% by mass from the viewpoint of tear resistance.

<Modified butadiene rubber>
As described above, the diene rubber contained in the rubber composition of the present invention includes a modified butadiene rubber obtained by modifying a butadiene rubber with a nitrone compound (hereinafter also referred to as “nitrone-modified butadiene rubber”). It is.

(Butadiene rubber)
The butadiene rubber used for producing the nitrone-modified butadiene rubber is not particularly limited.
Although it does not restrict | limit especially as a butadiene monomer used for manufacture of the said butadiene rubber, For example, 1, 3- butadiene, 2-chloro- 1, 3- butadiene etc. are mentioned. Among these, it is preferable to use 1,3-butadiene. These butadiene monomers can be used alone or in combination.

  The weight average molecular weight (Mw) of the butadiene rubber is not particularly limited, but is preferably from 100,000 to 1,500,000, and preferably from 300,000 to 1,300,000 from the viewpoint of handleability. More preferred. In the present specification, the weight average molecular weight (Mw) is measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

(Nitron compounds)
The nitrone compound used for the production of the nitrone-modified butadiene rubber is not particularly limited as long as it is a compound having a nitrone group represented by the following formula (1).

  In the above formula (1), * represents a bonding position.

  The nitrone compound is preferably a compound represented by the following formula (2).

  In the above formula (2), X and Y each independently represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.

  Examples of the aliphatic hydrocarbon group represented by X or Y include an alkyl group, a cycloalkyl group, and an alkenyl group. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, Examples thereof include a tert-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, n-hexyl group, n-heptyl group, n-octyl group and the like. Of the alkyl group is preferable, and an alkyl group having 1 to 6 carbon atoms is more preferable. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Among them, a cycloalkyl group having 3 to 10 carbon atoms is preferable, and a cycloalkyl group having 3 to 6 carbon atoms is preferable. More preferred. Examples of the alkenyl group include a vinyl group, a 1-propenyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group, and among them, an alkenyl group having 2 to 18 carbon atoms is preferable. An alkenyl group having 2 to 6 carbon atoms is more preferable.

Examples of the aromatic hydrocarbon group represented by X or Y include an aryl group and an aralkyl group.
Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. Among them, an aryl group having 6 to 14 carbon atoms is preferable, and an aryl group having 6 to 10 carbon atoms is more preferable. A phenyl group and a naphthyl group are more preferable.
Examples of the aralkyl group include a benzyl group, a phenethyl group, and a phenylpropyl group. Among them, an aralkyl group having 7 to 13 carbon atoms is preferable, an aralkyl group having 7 to 11 carbon atoms is more preferable, and a benzyl group is preferable. Further preferred.

  Examples of the aromatic heterocyclic group represented by X or Y include, for example, pyrrolyl group, furyl group, thienyl group, pyrazolyl group, imidazolyl group (imidazole group), oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, pyridyl group (Pyridine group), furan group, thiophene group, pyridazinyl group, pyrimidinyl group, pyrazinyl group and the like. Of these, a pyridyl group is preferable.

The substituent that the group represented by X or Y may have is not particularly limited, and examples thereof include an alkyl group having 1 to 4 carbon atoms, a hydroxy group, an amino group, a nitro group, a carboxy group, a sulfonyl group, An alkoxy group, a halogen atom, etc. are mentioned. Of these, a carboxy group is preferable.
Examples of the aromatic hydrocarbon group having such a substituent include an aryl group having a substituent such as a tolyl group and a xylyl group; and a substituent such as a methylbenzyl group, an ethylbenzyl group, and a methylphenethyl group. An aralkyl group; and the like.

  The compound represented by the above formula (2) is preferably a compound represented by the following formula (3).

In formula (3), m and n each independently represent an integer of 0 to 5, and the sum of m and n is 1 or more.
The integer represented by m is preferably an integer of 0 to 2, and more preferably an integer of 0 to 1, because the solubility in a solvent at the time of synthesizing a nitrone compound becomes good and the synthesis becomes easy.
The integer represented by n is preferably an integer of 0 to 2, and more preferably an integer of 0 to 1, because the solubility in a solvent at the time of synthesizing a nitrone compound is improved and the synthesis is facilitated.
Moreover, 1-4 are preferable and, as for the sum total (m + n) of m and n, 1-2 are more preferable.

  Although it does not restrict | limit especially as such carboxy nitrone represented by Formula (3), N-phenyl- (alpha)-(4-carboxyphenyl) nitrone represented by following formula (3-1), following formula (3- 2) N-phenyl-α- (3-carboxyphenyl) nitrone represented by the following formula (3-3), N-phenyl-α- (2-carboxyphenyl) nitrone represented by the following formula (3-3), 4) N- (4-carboxyphenyl) -α-phenylnitrone represented by the following formula (3-5), and N- (3-carboxyphenyl) -α-phenylnitrone represented by the following formula (3-5) A compound selected from the group consisting of N- (2-carboxyphenyl) -α-phenylnitrone represented by 3-6) is preferable.

  The method for synthesizing the nitrone compound is not particularly limited, and a conventionally known method can be used. For example, a compound having a hydroxyamino group (—NHOH) and a compound having an aldehyde group (—CHO) have a molar ratio of hydroxyamino group to aldehyde group (—NHOH / —CHO) of 1.0 to 1. By stirring in an amount of 5 in an organic solvent (for example, methanol, ethanol, tetrahydrofuran, etc.) at room temperature for 1 to 24 hours, both groups react to give a nitrone compound having a nitrone group.

(Method for producing nitrone-modified butadiene rubber)
The method for modifying the butadiene rubber with the nitrone compound is not particularly limited, and examples thereof include a method of mixing the butadiene rubber described above and the nitrone compound described above at 100 to 200 ° C. for 1 to 30 minutes.
At this time, as shown in the following formula (4-1) or the following formula (4-2), a cycloaddition reaction occurs between the double bond of the butadiene rubber and the nitrone group of the nitrone compound, Give a five-membered ring. In addition, following formula (4-1) represents reaction of the double bond derived from the conjugated diene which butadiene rubber (1,4-bond) has, and a nitrone compound, and following formula (4-2) is butadiene rubber (1 , 2-bond) represents a reaction between a double bond and a nitrone compound. Formulas (4-1) and (4-2) represent reactions when butadiene is 1,3-butadiene, but five-membered by the same reaction when butadiene is other than 1,3-butadiene. Give a ring.

  The amount of the nitrone compound used for modification is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the butadiene rubber.

(Modification rate)
The modification rate of the nitrone-modified butadiene rubber is not particularly limited, but is preferably 0.02 to 4.0 mol%, and more preferably 0.04 to 3.0 mol%.
Here, the modification rate represents the ratio (mol%) modified by the nitrone compound among all the double bonds of the butadiene rubber. For example, if the butadiene is 1,3-butadiene, the nitrone compound The ratio (mol%) by which the structure of the said Formula (4-1) or the said Formula (4-2) was formed by modification | denaturation by represents. The modification rate can be determined, for example, by performing NMR measurement of the butadiene rubber and nitrone-modified butadiene rubber (that is, butadiene rubber before and after modification).
In the present specification, a nitrone-modified butadiene rubber having a modification rate of 100 mol% also corresponds to a diene rubber.

  The content of the nitrone-modified butadiene rubber in the diene rubber is not particularly limited as long as it is 15 to 60% by mass. However, because the modulus becomes higher and the bending fatigue resistance is further improved, 20 to 60% by mass. It is preferable and it is more preferable that it is 25-50 mass%.

〔Carbon black〕
The carbon black contained in the rubber composition of the present invention is not particularly limited. For example, SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS Various grades such as FEF, GPF, and SRF can be used. Of these, GPF and FEF are preferable.
The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is not particularly limited, but is preferably ^{20 to} 40 m ² / g. Especially, it is more preferable that it is 25-35 m < ² > / g.
Here, the nitrogen adsorption specific surface area (N ₂ SA) is the nitrogen adsorption amount on the carbon black surface according to JIS K6217-2: 2001 “Part 2: Determination of specific surface area—nitrogen adsorption method—single point method”. It is a measured value.

  The carbon black content in the rubber composition of the present invention is not particularly limited, but is preferably 30 to 60 parts by mass, more preferably 35 to 55 parts by mass with respect to 100 parts by mass of the diene rubber. .

[Optional ingredients]
The rubber composition of the present invention can contain other additives as necessary within a range not impairing the object of the present invention.
Examples of the additives include silica, silane coupling agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, plasticizers, softening agents, vulcanization aids, flame retardants, weathering agents, heat resistance agents, and the like. It is done.
Specific examples of the vulcanizing agent include sulfur and zinc oxide; organic sulfur-containing compounds such as TMTD; organic peroxides such as dicumyl peroxide; and the like.
Specific examples of the vulcanization accelerator include sulfenamides such as N-tert-butyl-2-benzothiazolylsulfenamide; thiazoles such as mercaptobenzothiazole; tetramethylthiuram monosulfide and the like. Thiurams; stearic acid; and the like.
Specific examples of the antiaging agent include ketone / amine condensates such as TMDQ; amines such as DNPD; monophenols such as styrenated phenol; and the like.
Specific examples of the plasticizer include phthalic acid derivatives (for example, DBP, DOP and the like), sebacic acid derivatives (for example, DBS and the like) monoesters, and the like.
Specific examples of the softening agent include paraffinic oil (process oil).

[Method for producing rubber composition for air spring]
The method for producing the rubber composition of the present invention is not particularly limited, and specific examples thereof include, for example, kneading the above-described components using a known method and apparatus (for example, a Banbury mixer, a kneader, a roll, etc.). The method of doing is mentioned. When the rubber composition of the present invention contains sulfur or a vulcanization accelerator, components other than sulfur and the vulcanization accelerator are first mixed at a high temperature (preferably 40 to 160 ° C.), cooled, and then sulfur. Or it is preferable to mix a vulcanization accelerator.
The rubber composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[Air spring]
The air spring of this invention is an air spring which has a structural member formed using the rubber composition for air springs of this invention.
Since the air spring of the present invention has a constituent member formed using the rubber composition of the present invention, as described above, it exhibits a high modulus and good bending fatigue resistance.
Examples of air springs that can be used with the rubber composition for air springs of the present invention include conventionally known air springs used in pillow spring devices for railway vehicles, air suspensions for automobiles, and the like. A specific example is an air spring described in Japanese Patent No. 326818.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

<Synthesis of nitrone compound (carboxynitrone)>
Methanol (900 mL) warmed to 40 ° C. was placed in a 2 L eggplant flask, and terephthalaldehyde acid (30.0 g) represented by the following formula (b-1) was added and dissolved therein. To this solution was added phenylhydroxyamine (21.8 g) represented by the following formula (a-1) dissolved in methanol (100 mL), and the mixture was stirred at room temperature for 19 hours. After completion of stirring, nitrone compound (carboxynitrone) represented by the following formula (c-1) was obtained by recrystallization from methanol (41.7 g). The yield was 86%.

<Synthesis of nitrone-modified butadiene rubber>
Butadiene rubber (Nipol BR1220, manufactured by Nippon Zeon Co., Ltd.) was charged into a Banbury mixer at 120 ° C. and masticated for 2 minutes. Thereafter, 1 part by mass of the nitrone compound synthesized as described above was added to 100 parts by mass of butadiene rubber and mixed at 160 ° C. for 5 minutes to modify the butadiene rubber with the nitrone compound. In this way, a nitrone-modified butadiene rubber was obtained.
When the obtained nitrone modified butadiene rubber was subjected to NMR measurement and the modification rate was determined, the modification rate of the nitrone modified butadiene rubber was 0.1 mol%. Specifically, the modification rate was determined as follows. That is, for the butadiene rubber before and after modification, the peak area around 8.08 ppm (attributed to two protons adjacent to the carboxy group) by ¹ H-NMR measurement (CDCl ₃ , 400 MHz, TMS) using CDCl ₃ as a solvent. Was measured to determine the denaturation rate. The ¹ H-NMR measurement of the nitrone-modified butadiene rubber was carried out using a sample dried under reduced pressure after repeating twice purification by dissolving the nitrone-modified butadiene rubber in toluene and precipitating it in methanol.

[Comparative Examples 1-2 and Examples 1-2]
<Preparation of rubber composition for air spring>
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in Table 1 below.
Specifically, first, components excluding sulfur and a vulcanization accelerator among the components shown in Table 1 below were mixed with a Banbury mixer at 60 ° C. for 5 minutes. Next, sulfur and a vulcanization accelerator were mixed using a roll to obtain a rubber composition for an air spring.

<Evaluation of modulus>
The obtained rubber composition was vulcanized at 150 ° C. for 15 minutes to prepare a vulcanized rubber composition.
Next, the prepared vulcanized rubber composition was cut into a dumbbell shape (dumbbell shape No. 3) having a thickness of 2 mm to obtain a test piece.
About the obtained test piece, 100% modulus (stress at the time of 200% deformation) [MPa] and 300% modulus (stress at the time of 300% deformation) [MPa] were measured according to JIS K6251: 2010. The results are shown in Table 1 below.
In addition, the result was represented by an index with the value of Comparative Example 1 as 100 for 100% modulus (M100), and represented by an index with the value of Comparative Example 1 as 100 for 300% modulus (M300). The larger the index, the higher the modulus.

<Evaluation of bending fatigue resistance>
The crack generation test by repeated bending was performed according to the bending crack growth test described in JIS K 6260: 2010.
Specifically, a vulcanized rubber composition is prepared in the same manner as in the above-described modulus evaluation, and a test piece having a size and thickness specified in the above-mentioned flex crack growth test is prepared. The test piece into which the cut was made was tested with a demacha bending tester (temperature: room temperature, stroke: 20 mm, number of bendings per minute: 300 ± 10). And the crack length after 400,000 times bending | flexion was investigated.
The results are shown in Table 1 below (flexural fatigue resistance). The results were expressed as an index with the crack length of Comparative Example 1 as 100. The smaller the crack length, the better the bending fatigue resistance.

<Evaluation of tear resistance>
A vulcanized rubber composition was prepared in the same manner as the modulus evaluation described above.
Next, in accordance with JIS K6252: 2001, a crescent-shaped test piece was cut out from each of the prepared vulcanized rubber compositions, and a notch with a length of 1.0 ± 0.2 mm was put in the central indented portion in a direction perpendicular to the main axis. . A test was conducted at a moving speed of the test piece gripper of 500 mm / min, and the tearing force (TR) [kN / m] was measured at room temperature.
The results are shown in Table 1 below (Tear resistance). The results are expressed as an index with the tearing force of Comparative Example 1 as 100. The higher the tear strength, the better the tear resistance.

Details of each component shown in Table 1 are as follows.
・ NR: Natural rubber (RSS # 3)
BR: Butadiene rubber (Nipol BR1220, manufactured by Nippon Zeon Co., Ltd.)
Nitron-modified BR: Nitron-modified butadiene rubber synthesized as described above Carbon black: GPF grade carbon black (Diablack G, nitrogen adsorption specific surface area: 29 m ² / g, manufactured by Mitsubishi Chemical Corporation)
・ Zinc oxide: Zinc Hana 3 (manufactured by Shodo Chemical Co., Ltd.)
Aroma oil: A-OMIX (Sankyo Oil Chemical Co., Ltd.)
・ Sulfur: Oil-treated sulfur (Hosoi Chemical Co., Ltd.)
・ Vulcanization accelerator: Noxeller CZ-G (manufactured by Ouchi Shinsei Chemical Co., Ltd.)

  As can be seen from Table 1, when a specific amount of nitrone-modified butadiene rubber is blended as a diene rubber, it has a higher modulus than that of Comparative Example 1 and Comparative Example 2 in which a small amount of nitrone-modified butadiene rubber is blended. It has been found that the bending fatigue property is also improved and the tear resistance is improved.

Claims (6)

Contains diene rubber and carbon black,
The diene rubber includes natural rubber and a modified butadiene rubber obtained by modifying a butadiene rubber with a nitrone compound,
A rubber composition for an air spring, wherein the content of the modified butadiene rubber in the diene rubber is 15 to 60% by mass.   The rubber composition for an air spring according to claim 1, wherein a content of the carbon black is 30 to 60 parts by mass with respect to 100 parts by mass of the diene rubber. The rubber composition for an air spring according to claim 1 or 2, wherein the carbon black has a nitrogen adsorption specific surface area of 20 to 40 m ² / g.   The nitrone compound is N-phenyl-α- (4-carboxyphenyl) nitrone, N-phenyl-α- (3-carboxyphenyl) nitrone, N-phenyl-α- (2-carboxyphenyl) nitrone, N- ( A compound selected from the group consisting of 4-carboxyphenyl) -α-phenylnitrone, N- (3-carboxyphenyl) -α-phenylnitrone and N- (2-carboxyphenyl) -α-phenylnitrone. Item 4. The rubber composition for an air spring according to any one of Items 1 to 3. The rubber composition for an air spring according to any one of claims 1 to 4, wherein a modified rate of the modified butadiene rubber is 0.02 to 4.0 mol%.
Here, the modification rate represents the ratio (mol%) modified by the nitrone compound among all the double bonds derived from the conjugated diene of the conjugated diene polymer.   An air spring comprising a constituent member using the rubber composition for an air spring according to any one of claims 1 to 5.