JP5095368B2 - Rubber composition for bead apex and tire having bead apex using the same - Google Patents

Description

  The present invention relates to a rubber composition for bead apex and a tire having a bead apex using the same.

Conventionally, the rubber composition for a bead apex of a tire has been focused only on increasing the complex elastic modulus (E ^* ) and improving the handling stability.

  However, even if the driving stability is improved, a certain time is required when driving with a tire for a multipurpose sports vehicle (SUV) having a long bead apex or when driving in the cold season. When the vehicle is started after being stopped, there is a problem that deformation distortion, that is, a flat spot is accumulated in the bead apex of the tire until the temperature of the tire rises, which causes deterioration in fuel efficiency. In order to prevent the occurrence of such a flat spot, it is effective to reduce tan δ.

From such a background, it is necessary to increase E ^* and reduce tan δ as a rubber composition for bead apex.

As a method for increasing E ^* , for example, there is a method of adding 1,2-syndiotactic polybutadiene crystal (SPB), but in this case, there is a problem that tan δ increases. As a method for reducing tan δ, for example, there is a method for reducing the content of filler such as carbon black. In this case, however, there is a problem that E * is lowered.

That is, E ^* and tan δ are opposite physical properties, and conventionally it has been difficult to improve both physical properties.

  Patent Document 1 discloses a bead apex rubber that can improve durability around a bead without impairing hardness, dynamic elastic modulus, wear resistance, and the like by containing a predetermined amount of a rubber component and waste paper. A composition is disclosed. However, there is still room for improvement in both handling stability and fuel efficiency.

JP 2002-37929 A

  The present invention provides a rubber composition for a bead apex excellent in handling stability and excellent in fuel efficiency, a run-flat tire having a bead apex using the same, and a tire for a multipurpose sports car. For the purpose.

  The present invention contains 5 to 18 parts by weight of phenol resin and / or modified phenol resin, 0 to 3 parts by weight of non-reactive alkylphenol resin, and 55 to 80 parts by weight of carbon black with respect to 100 parts by weight of the rubber component. The present invention relates to a rubber composition for bead apex.

  The rubber component is preferably composed of NR and / or IR and a butadiene rubber containing 1,2-syndiotactic polybutadiene crystals, a high cis content butadiene rubber or an emulsion-polymerized styrene-butadiene rubber.

  Furthermore, it is preferable to contain 5-8 weight part of sulfur with respect to 100 weight part of rubber components.

  The present invention also relates to a run-flat tire having a bead apex using the bead apex rubber composition.

  Furthermore, the present invention also relates to a multipurpose sports vehicle tire having a bead apex using the rubber composition for bead apex.

  According to the present invention, the rubber component contains a predetermined amount of a phenol resin and / or a modified phenol resin, a non-reactive alkylphenol resin, and carbon black, so that the steering stability is excellent and the fuel efficiency is excellent. In addition, a bead apex rubber composition, a run flat tire having a bead apex using the bead apex, a multipurpose sports vehicle tire, and a multipurpose sports car run flat tire can be provided.

  The rubber composition for bead apex of the present invention contains a phenol resin and / or a modified phenol resin, a non-reactive alkylphenol resin, and carbon black with respect to the rubber component.

  Examples of the rubber component include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), modified BR, and modified SBR.

  As NR, those generally used in the rubber industry such as RSS # 3 grade can be used. Also, IR that is common in the rubber industry can be used.

  When NR and / or IR is contained as the rubber component, the content of NR and / or IR is preferably 20% by weight or more, preferably 25% by weight or more in the rubber component from the viewpoint of improving the breaking strength and workability. More preferred is 30% by weight or more. In addition, the content of NR and / or IR is preferably 90% by weight or less, more preferably 85% by weight or less, and more preferably 80% by weight or less in the rubber component from the viewpoint that the decrease in hardness (Hs) due to reversion is small. preferable.

  Further, as BR, butadiene rubber containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), BR with high cis content, and as SBR, emulsion-polymerized styrene butadiene rubber (E-SBR) is preferable. .

  The melting point of SPB in the SPB-containing BR is preferably 180 ° C. or higher, and more preferably 190 ° C. or higher. When the melting point of SPB is less than 180 ° C., crystals melt during vulcanization of the tire by pressing, and the hardness tends to decrease. The melting point of SPB is preferably 220 ° C. or lower, and more preferably 210 ° C. or lower. When the melting point of SPB exceeds 220 ° C., the molecular weight of the SPB-containing BR increases, so that dispersibility tends to deteriorate in the rubber composition.

  The content of boiling n-hexane insoluble matter in the SPB-containing BR is preferably 2.5% by weight or more, and more preferably 8% by weight or more. When the content of the boiling n-hexane insoluble matter is less than 2.5% by weight, there is a tendency that sufficient hardness of the rubber composition cannot be obtained. Further, the content of boiling n-hexane insolubles is preferably 22% by weight or less, more preferably 20% by weight or less, and further preferably 18% by weight or less. When the content of the boiling n-hexane insoluble matter exceeds 22% by weight, the viscosity of the SPB-containing BR itself is high, and the dispersibility of the SPB-containing BR and filler in the rubber composition tends to deteriorate. Here, the boiling n-hexane insoluble indicates SPB in the SPB-containing BR.

The content of the SPB-containing BR is 9% by weight or more in the rubber component from the viewpoint that the complex elastic modulus (E ^* ) can be increased and that the bead apex is upright during extrusion. It is preferably 10% by weight or more, more preferably 11% by weight or more. Further, the content of the SPB-containing BR is preferably 80% by weight or less, more preferably 75% by weight or less, more preferably 70% by weight in the rubber component from the viewpoints of high dispersibility, small tan δ and excellent fuel economy. % Or less is more preferable.

  As E-SBR, those usually used in the rubber industry can be used.

  The upper limit of the styrene unit amount of the E-SBR is preferably 45% by weight, more preferably 40% by weight in the E-SBR. When the styrene unit amount exceeds 45% by weight, tan δ tends to increase.

The content of E-SBR in the rubber component is preferably 10% by weight or more, preferably 15% by weight or more in the rubber component from the viewpoint that the complex elastic modulus (E ^* ) can be increased and reversion can be suppressed. More preferred is 20% by weight or more. Further, the content of E-SBR is preferably 60% by weight or less, more preferably 50% by weight or less, and still more preferably 40% by weight or less in the rubber component from the viewpoint that tan δ is small and fuel efficiency is excellent.

As the rubber component, a combination of NR and / or IR and E-SBR, and a combination of NR and / or IR and SPB-containing BR are preferable from the viewpoint of improving breaking strength and complex elastic modulus (E ^* ) and reducing tan δ. .

  The phenol resin is not particularly limited, and examples thereof include those obtained by reacting phenols with aldehydes such as formaldehyde, acetaldehyde and furfural with an acid or alkali catalyst.

  Examples of the modified phenol resin include a phenol resin modified with a compound such as cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acid, rosin, alkylbenzene resin, aniline, and melamine.

  As the phenol resin and / or the modified phenol resin, a modified phenol resin is preferable, and a cashew oil-modified phenol resin or a rosin-modified phenol resin is preferable because Hs can be improved.

で示される変性フェノール樹脂である。 Here, cashew oil-modified phenol resin is represented by the formula (1):

It is the modified phenol resin shown by these.

  In the formula, n is an integer of 1 to 9 and preferably 5 to 6 in that the reactivity is good and the dispersibility is improved.

  The content of the phenol resin and / or the modified phenol resin is 5 parts by weight or more, preferably 5.5 parts by weight or more with respect to 100 parts by weight of the rubber component, from the viewpoint that sufficient Hs is obtained. 0 parts by weight or more is more preferable. Further, from the viewpoint that tan δ is small and excellent in fuel efficiency, it is 18 parts by weight or less, preferably 17 parts by weight or less, more preferably 16 parts by weight or less with respect to 100 parts by weight of the rubber component.

  The non-reactive alkylphenol resin refers to an alkylphenol resin having no reactive sites at the ortho-position and para-position (particularly para-position) of the hydroxyl group of the benzene ring in the chain. That is, the non-reactive alkylphenol resin is different from a resin having high reactivity at the para position, such as a resorcin resin having two hydroxyl groups of the benzene ring in the chain.

および式（３）：

で示されるものがあげられる。式（２）におけるｎは、１〜１０が好ましく、２〜９がより好ましい。Ｒは、炭素数４〜１５、好ましくは炭素数６〜１０のアルキル基であり、具体的には、オクチル基、ヘキシル基、デカン基などがあげられる。 Specific examples of non-reactive alkylphenol resins include the formula (2):

And formula (3):

What is indicated by. 1-10 are preferable and, as for n in Formula (2), 2-9 are more preferable. R is an alkyl group having 4 to 15 carbon atoms, preferably 6 to 10 carbon atoms, and specific examples include octyl group, hexyl group, decane group and the like.

  Moreover, 1-10 are preferable and, as for m in Formula (3), 2-9 are more preferable.

  The content of the non-reactive alkylphenol resin is preferably 0 to 3 parts by weight with respect to 100 parts by weight of the rubber component.

  The content of carbon black is 55 parts by weight or more, preferably 57 parts by weight or more, and more preferably 59 parts by weight or more with respect to 100 parts by weight of the rubber component in view of high Hs. Further, the content of carbon black is 80 parts by weight or less, more preferably 78 parts by weight or less, more preferably 76 parts by weight or less with respect to 100 parts by weight of the rubber component from the viewpoint of improving breaking strength and reducing tan δ. Is more preferable.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 30 m ² / g or more, more preferably 32 m ² / g or more, and still more preferably 34 m ² / g or more from the viewpoint that Hs is high. Further, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black from the viewpoint of reducing the tan [delta, preferably 100 m ² / g or less, more preferably 90m ² / g, more preferably 80 m ² / g or less .

  Moreover, you may contain aroma oil as an arbitrary component. The content of the aroma oil is preferably 4 parts by weight or less, more preferably 3 parts by weight or less from the viewpoint that Hs is high, and may not be contained. Note that aliphatic C5 petroleum resins and C9 petroleum resins are dissimilar in structure to phenolic resins and inhibit the dispersion of phenolic resins, and tan δ increases, resulting in poor fuel economy. From the viewpoint, it is preferable not to contain.

Sulfur used in the present invention is preferably insoluble sulfur because of its excellent dispersibility, and specific examples thereof include flexex HSOT20 manufactured by Flexis, Sanfel EX manufactured by Sanshin Chemical Industry Co., Ltd., and the like. . Here, insoluble sulfur refers to high molecular weight sulfur in which the eight-membered cyclic structure of S ₈ undergoes radical cleavage and is connected in a chain, and is insoluble in carbon disulfide and rubber-like hydrocarbons. It is.

  The content of sulfur is preferably 4.0 parts by weight or more, more preferably 4.5 parts by weight or more, and 5.0 parts by weight or more with respect to 100 parts by weight of the rubber component from the viewpoint that sufficient Hs can be obtained. Is more preferable, and 5.2 parts by weight or more is particularly preferable. Further, the content of sulfur is preferably 8 parts by weight or less with respect to 100 parts by weight of the rubber component from the viewpoint of being less likely to bloom on the surface during processing or vulcanization, and from the viewpoint of improving the breaking strength. More preferred is less than or equal to parts by weight, and even more preferred is less than or equal to 7.0 parts by weight. In addition, when insoluble sulfur is contained as sulfur, the sulfur content represents the sulfur content excluding the oil in the insoluble sulfur.

The rubber composition for bead apex of the present invention further includes a citraconic compound, an organic thiosulfate compound, an alkylphenol / sulfur chloride condensate, and a formula:
R ¹ —S—S—A—S—S—R ²
(Wherein A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R ² each independently represents a monovalent organic group containing a nitrogen atom) and at least selected from the group consisting of compounds represented by It is preferable to include one kind of vulcanization acceleration auxiliary.

  As the citraconimide compound, biscitraconimides are preferable because they are thermally stable and have excellent dispersibility in rubber. Specifically, 1,2-biscitraconimidomethylbenzene, 1,3-biscitraconimidomethylbenzene, 1,4-biscitraconimidomethylbenzene, 1,6-biscitraconimidomethylbenzene, 2,3-bis Citraconimidomethyltoluene, 2,4-biscitraconimidomethyltoluene, 2,5-biscitraconimidomethyltoluene, 2,6-biscitraconimidomethyltoluene, 1,2-biscitraconimidoethylbenzene, 1,3-biscitracon Imidoethylbenzene, 1,4-biscitraconimidoethylbenzene, 1,6-biscitraconimidoethylbenzene, 2,3-biscitraconimidoethyltoluene, 2,4-biscitraconimidoethyltoluene, 2,5-biscitraconimidoethyltoluene Emissions, such as 2,6-biscitraconimide ethyltoluene and the like. Among these, 1,3-biscitraconimidomethylbenzene is preferable because it is thermally stable and has excellent dispersibility in rubber.

1,3-biscitraconimidomethylbenzene is represented by the following chemical formula.

The organic thiosulfate compound is represented by the following chemical formula.
MO ₃ S—S— (CH ₂ ) _m —S—SO ₃ M
(In the formula, m is 3 to 10, and M is lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel, or cobalt. Further, crystal water may be contained.)

  m is preferably from 3 to 10, and more preferably from 3 to 6. When m is 2 or less, sufficient heat fatigue resistance tends to be not obtained, and when m is 11 or more, the effect of improving heat fatigue resistance tends to be small although the molecular weight increases.

  M is preferably lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel or cobalt, and preferably potassium or sodium.

  Moreover, crystal water may be included in the molecule.

  Specific examples include sodium salt monohydrate and sodium salt dihydrate. For economic reasons, derivatives from sodium thiosulfate such as sodium 1,6-hexamethylenedithiosulfate dihydrate. Is preferred.

1,6-hexamethylenedithiosulfate sodium dihydrate is represented by the following chemical formula.

式中、ｎは１０以下が好ましい。 The alkylphenol / sulfur chloride condensate is represented by the following chemical formula.

In the formula, n is preferably 10 or less.

In addition, the following chemical formula R ¹ —S—S—A—S—S—R ²
Wherein A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R ² each independently represents a monovalent organic group containing a nitrogen atom, and A is an alkylene group Groups are preferred. Examples of the alkylene group include linear, branched, and cyclic groups, and there is no particular limitation, and any can be used, but a linear alkylene group is preferred.

2-10 are preferable and, as for carbon number of A, 4-8 are more preferable. If the carbon number of A is 1 or less, the thermal stability tends to be poor, and there is a tendency that the merit obtained from the S—S bond cannot be obtained. _It tends to be difficult to replace _x− .

  Examples of the alkylene group satisfying the above conditions include ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, decamethylene group and the like. Among them, a hexamethylene group is preferable because it smoothly substitutes for a polymer / polymer sulfur bridge and is thermally stable.

R ¹ and R ² are each preferably a monovalent organic group containing a nitrogen atom, more preferably an aromatic ring containing at least one, and a carbon atom bonded to a dithio group = N—C (= Those containing a linking group represented by S)-are more preferred.

R ¹ and R ² may be the same or different, but are preferably the same for reasons such as ease of production.

  Examples of the compound satisfying the above conditions include 1,2-bis (N, N′-dibenzylthiocarbamoyldithio) ethane, 1,3-bis (N, N′-dibenzylthiocarbamoyldithio) propane, 1, 4-bis (N, N′-dibenzylthiocarbamoyldithio) butane, 1,5-bis (N, N′-dibenzylthiocarbamoyldithio) pentane, 1,6-bis (N, N′-dibenzylthio) Carbamoyldithio) hexane, 1,7-bis (N, N′-dibenzylthiocarbamoyldithio) heptane, 1,8-bis (N, N′-dibenzylthiocarbamoyldithio) octane, 1,9-bis (N , N′-dibenzylthiocarbamoyldithio) nonane, 1,10-bis (N, N′-dibenzylthiocarbamoyldithio) decane and the like.

  Among these, 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane is preferable because it is thermally stable and has excellent polarizability.

  Among the four types of vulcanization accelerators described above, since sulfur is not contained in the molecular structure, it is thermally stable, and the initial vulcanization rate is excessively increased without releasing sulfur during crosslinking. 1,3-biscitraconimidomethylbenzene is preferred because it does not rapidly reach the target.

  Among the four types of vulcanization accelerating aids, when no citraconimide compound is contained, it is preferable to contain a citraconic imide compound because T10 is short and scorching is easy. Moreover, anti-aging agents, stearic acid, and the like conventionally used as vulcanization accelerating aids can be appropriately blended as necessary.

  The content of the vulcanization acceleration auxiliary is preferably 0.1 parts by weight or more, and more preferably 0.5 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content of the vulcanization acceleration auxiliary is less than 0.1 parts by weight, the hardness tends to be insufficient. Further, the content of the vulcanization acceleration auxiliary is preferably 3 parts by weight or less, and more preferably 2.7 parts by weight or less. When the content of the vulcanization acceleration auxiliary exceeds 3 parts by weight, the effect of increasing the hardness is already saturated and the cost tends to increase.

  The rubber composition for bead apex of the present invention preferably further contains zinc oxide.

  Zinc oxide may be normal zinc oxide that has been used in the rubber industry and has an average particle diameter of more than 200 nm, or may be fine zinc oxide having an average particle diameter of 200 nm or less.

  When normal zinc oxide is contained as zinc oxide, the content of zinc oxide is 4% by weight with respect to 100 parts by weight of the rubber component from the viewpoint of having a large effect of suppressing reversion and suppressing sulfur bloom. Part or more is preferable, and 5 parts by weight or more is more preferable. Further, the content of normal zinc oxide is preferably 15 parts by weight or less, preferably 12 parts by weight or less from the viewpoint that dispersibility is good, the breaking strength does not decrease, and elongation at break is large and good. More preferred.

  The bead apex rubber composition of the present invention is also at least one selected from the group consisting of hexamethylenetetramine (HMT), hexamethoxymethylol melamine (HMMM), and hexamethoxymethylol pantamethyl ether (HMMPME). Compounds can be included. Among them, HMT is preferable because it can effectively release a methylene group in a small amount and is inexpensive.

  In addition, when using HMT, HMMM, and HMMPME, the formaldehyde (methylene) generated from them is used for the semi-crosslinking of the phenol resin, and the phenol resin and / or the modified phenol resin is used in advance because the formaldehyde does not scatter in the air. HMT, HMMM, and HMMPME can be mixed and then kneaded with other compounding agents.

  The content of at least one compound selected from the group consisting of HMT, HMMM and HMMPME is preferably 0.5 parts by weight or more and more preferably 0.7 parts by weight or more with respect to 100 parts by weight of the rubber component. If the content of at least one compound selected from the group consisting of HMT, HMMM and HMMPME is less than 0.5 parts by weight, the formaldehyde (methylene) concentration tends to be too low, and the phenol resin tends to be insufficiently crosslinked. There is. Further, the content of at least one compound selected from the group consisting of HMT, HMMM and HMMPME is preferably 3.0 parts by weight or less, and more preferably 2.0 parts by weight or less. When the content of at least one compound selected from the group consisting of HMT, HMMM and HMMPME exceeds 3.0 parts by weight, when HMT is contained, ammonia released together with methylene is mixed with the adjacent case formulation and code. When HMMM or HMMPME is contained, ammonia is not released, but the rubber viscosity tends to increase excessively.

  The rubber composition for bead apex of the present invention includes the rubber component, phenol resin and / or modified phenol resin, non-reactive alkylphenol resin, carbon black, sulfur, vulcanization accelerator, zinc oxide and HMT, HMMM and In addition to at least one compound selected from the group consisting of HMMPME, compounding agents conventionally used in the rubber industry, for example, various vulcanization accelerators, retarders such as N-cyclohexylthio-phthalamide (CTP), calcium carbonate Etc. can be appropriately blended as necessary.

  The rubber composition for bead apex of the present invention is produced by a general method. That is, a rubber composition can be produced by kneading the compounding agent and, if necessary, an additive with a Banbury mixer, a kneader, an open roll, etc., and then vulcanizing.

  The tire of the present invention is produced by a usual method using the rubber composition for bead apex of the present invention. That is, if necessary, the rubber composition of the present invention blended with the above-mentioned compounding agent is extruded in accordance with the shape of the bead apex of the tire at an unvulcanized stage and is processed on a tire molding machine in a usual manner. An unvulcanized tire is formed by molding. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

  In particular, the tire of the present invention is preferably a run-flat tire having a reinforcing rubber layer between a sidewall and a carcass, or a tire for a multipurpose sports vehicle having a large displacement.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

（式中ｎは１〜９の整数である）
アルキルフェノール樹脂：（株）日本触媒製のＳＰ１０６８
ＳＰ１０６８の化学式を以下に示す。

（式中、Ｒはオクチル基であり、ｎは１〜９の整数である）
Ｃ５粘着樹脂：三井化学（株）製のハイレッツＧ−１００
Ｃ９粘着樹脂：東ソー（株）製のペトコールＸＬ
アロマオイル：出光興産（株）製のダイアナプロセスオイルＡＨ−２４
老化防止剤６Ｃ：大内新興化学工業（株）製のノクラック６Ｃ（Ｎ−１，３−ジメチルブチル−Ｎ’−フェニル−ｐ−フェニレンジアミン）
酸化亜鉛：三井金属鉱業（株）製（平均粒子径：２９０ｎｍ）
ステアリン酸：日本油脂（株）製
硫黄：フレキシス製のクリステックスＨＳＯＴ２０（硫黄８０重量％およびオイル分２０重量％含む不溶性硫黄）
加硫促進剤ＨＭＴ：ヘキサメチレンテトラミン（ＨＭＴ）、大内新興化学工業（株）製のノクセラーＨ
加硫促進剤ＮＳ：大内新興化学工業（株）製のノクセラーＮＳ（Ｎ−ｔｅｒｔ−ブチル−２−ベンゾチアゾリルスルフェンアミド）
加硫促進補助剤ＰＫ９００：フレキシス社製のＰＥＲＫＡＬＩＮＫ９００（１，３−ビス（シトラコンイミドメチル）ベンゼン）

Ｎ−シクロヘキシルチオ−フタルアミド（ＣＴＰ）：大内新興化学工業（株）製のＣＴＰ Next, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber (NR): RSS # 3
E-SBR: Emulsion polymerization SBR1502 manufactured by JSR Corporation
Butadiene rubber containing 1,2-syndiotactic butadiene crystals (BR containing SPB): VCR412 manufactured by Ube Industries, Ltd. (syndiotactic-1,2-polybutadiene crystal dispersion, containing boiling n-hexane insoluble matter) (Amount: 12% by weight, average particle size of syndiotactic-1,2-polybutadiene crystal: 250 nm)
Isoprene rubber (IR): IR2200 manufactured by Nippon Zeon Co., Ltd.
Carbon black: Show Black N550 manufactured by Cabot Japan
Calcium carbonate: Hakuhoka CC manufactured by Shiroishi Kogyo Co., Ltd. (average particle size: 2 μm, BET: 26.0 m ² / g, specific gravity: 2.55, pH: 8.8)
Modified phenolic resin: PR12686 (cashew oil-modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.
The chemical formula of PR12686 is shown below.

(Where n is an integer from 1 to 9)
Alkylphenol resin: SP1068 manufactured by Nippon Shokubai Co., Ltd.
The chemical formula of SP1068 is shown below.

(In the formula, R is an octyl group, and n is an integer of 1 to 9)
C5 adhesive resin: Highlets G-100 manufactured by Mitsui Chemicals, Inc.
C9 adhesive resin: Petcoal XL manufactured by Tosoh Corporation
Aroma oil: Diana Process Oil AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent 6C: Nocrack 6C (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Zinc oxide: manufactured by Mitsui Kinzoku Mining Co., Ltd. (average particle size: 290 nm)
Stearic acid: Sulfur manufactured by Nippon Oil & Fats Co., Ltd .: Kristex HSOT20 manufactured by Flexis (insoluble sulfur containing 80% by weight of sulfur and 20% by weight of oil)
Vulcanization accelerator HMT: Hexamethylenetetramine (HMT), Noxeller H manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator NS: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator PK900: PERKALINK900 (1,3-bis (citraconimidomethyl) benzene) manufactured by Flexis

N-cyclohexylthio-phthalamide (CTP): CTP manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-10 and Comparative Examples 1-9
According to the formulation shown in Tables 1 and 2, using a Banbury mixer, chemicals other than the vulcanization acceleration auxiliary PK900, HMT, sulfur, vulcanization accelerator NS and CTP were kneaded to obtain a kneaded product. Next, using an open roll, the obtained kneaded product was kneaded with the addition of vulcanization accelerators PK900, HMT, sulfur, vulcanization accelerator NS and CTP, and an unvulcanized rubber composition was obtained. . The obtained unvulcanized rubber composition was press vulcanized for 12 minutes at 170 ° C. to prepare vulcanized rubber compositions of Examples 1 to 10 and Comparative Examples 1 to 9.

(Viscoelasticity test)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the complex elastic modulus (E ^* ) of the vulcanized rubber composition under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2% ^. ) And loss tangent (tan δ). Larger E ^* indicates higher rigidity and better steering stability, and smaller tan δ indicates better fuel efficiency.

(Tire manufacturing)
The unvulcanized rubber composition is molded into a bead apex shape and bonded together with other tire members to produce an unvulcanized tire, and press vulcanized for 12 minutes at 170 ° C. Test tires 1 to 10 and Comparative Examples 1 to 9 (tire size: P265 / 65R17 100S, tire for SUV (displacement: 3500 cc)) were manufactured.

(Maneuvering stability)
Attach test tires to an SUV (displacement: 3500 cc), run the vehicle on a dry asphalt road test course with a road surface temperature of 25 ° C, and test the sensor stability in six stages with a test driver. did. The larger the numerical value, the better the steering stability. 5 ⁺ and 6 ⁺ indicate slightly better than 5 and 6, respectively, and 3 ⁻ indicates slightly inferior to 3.

(Rolling resistance test)
Under the conditions of 25 ° C., the rolling test was performed by running the test tire for passenger cars on a drum under the conditions of a load of 6.82 km, a tire internal pressure of 270 kPa, and a speed of 80 km / hour. And the rolling resistance index | exponent of the comparative example 1 was set to +/- 0, and the rolling resistance fall rate of each mixing | blending was displayed. In addition, rolling resistance is reduced, so that rolling resistance fall rate is small, and it shows that it is excellent in rolling resistance characteristics.

(Adhesion index)
After extruding the unvulcanized rubber composition into a bead apex, the adhesiveness between the rubber surface of the molded product and the rubber for covering the case cord for the tire is subjected to sensory evaluation (both adhesive and flat) by the molder, and the index Turned into. The greater the tack index, the better the adhesion between the case and the bead apex and the better the moldability. In addition, when the adhesive index is small, the case and the bead apex are peeled off or air accumulation is generated.

  The evaluation results of the above tests are shown in Tables 1 and 2.

Claims (4)

100 parts by weight of a rubber component comprising 30-80% by weight of natural rubber and / or isoprene rubber and butadiene rubber containing 1,2-syndiotactic polybutadiene crystals, high cis content butadiene rubber or emulsion polymerized styrene-butadiene rubber Against
5-18 parts by weight of phenolic resin and / or modified phenolic resin,
1.0 to 3.0 parts by weight of a non-reactive alkylphenol resin,
It is a rubber composition for bead apex containing 55 to 80 parts by weight of carbon black and 5.2 to 7.0 parts by weight of sulfur,
The non-reactive alkylphenol resin has only one hydroxyl group on the benzene ring in the chain, has no functional group at the ortho position and the meta position of the hydroxyl group, and has an alkyl group having 4 to 15 carbon atoms at the para position of the hydroxyl group. A non-reactive alkylphenol resin having
A rubber composition for a bead apex, wherein the phenol resin and / or the modified phenol resin has only one hydroxyl group in the benzene ring in the chain and has no functional group at the ortho, meta, and para positions of the hydroxyl group. Non-reactive alkylphenol resin
Formula (2):

(In Formula (2), n is 1-10 and R is a C4-C15 alkyl group.)
The rubber composition for bead apex according to claim 1, which is a non-reactive alkylphenol resin represented by the formula: A run flat tire having a bead apex using the rubber composition for bead apex according to claim 1. Tire for a sports utility vehicle having a bead apex prepared by using the claim 1 or 2 for a bead apex rubber composition.