JP7444647B2 - pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, organic fibers such as polyester fibers have a high initial modulus of elasticity and excellent dimensional stability under heat. Various adhesive compositions have been proposed to improve the adhesion between these fibers and rubber. There is a known technology that uses an RFL (resorcinol formalin latex) adhesive containing resorcinol, formalin, rubber latex, etc. as an adhesive composition and heat-cures the RFL adhesive to ensure adhesive strength. (For example, see Patent Documents 1 to 3.)

In addition, regarding adhesive compositions, techniques using resorcin-formalin resin, which is an initial condensation of resorcin and formalin (see Patent Documents 4 and 5), and pre-treatment of tire cords made of polyester fibers with epoxy resin, etc. Techniques for improving adhesive strength are known.
However, in recent years, there has been a demand for reducing the amount of resorcinol used, which is commonly used in the above-mentioned adhesive compositions, in consideration of the working environment.

Therefore, several adhesive compositions and adhesive methods that do not contain resorcin and are environmentally friendly have been proposed (see, for example, Patent Document 6).
However, since adhesive compositions that do not contain resorcin require time to cure, further improvements are required in terms of productivity and adhesiveness.
Furthermore, when polyethylene terephthalate (PET) fibers are used as organic fibers to be bonded, adhesive compositions that do not contain resorcinol often fail to provide sufficient adhesive performance, and improvements have been particularly desired. When polyester fiber materials, which are linear polymers with ester bonds in their main chains, such as polyethylene terephthalate, which has good thermal dimensional properties, are used as reinforcing materials for rubber products, they are structurally dense and This is because a polyester fiber material with a small number of functional groups can hardly be bonded with an adhesive composition obtained by mixing a latex such as RFL with a raw material that crosslinks water-soluble phenol.

In addition to the above-mentioned demand for environmentally friendly adhesive compositions, there is also a desire to develop tires with excellent tire durability and rolling resistance from the perspective of extending the life of tires.

Japanese Patent Application Publication No. 58-2370 Japanese Patent Application Publication No. 60-92371 Japanese Patent Application Publication No. 60-96674 Japanese Unexamined Patent Publication No. 63-249784 Special Publication No. 63-61433 Japanese Patent Application Publication No. 2010-255153

Therefore, an object of the present invention is to provide a pneumatic tire in which the adhesive composition coated on the organic fiber cord does not contain resorcinol, has a low burden on the environment, and has excellent rolling resistance. It's about doing.

The present inventors have proposed a carcass consisting of one or more carcass plies extending from a pair of bead portions to a tread portion via a sidewall portion, and a pair of carcass plies disposed inside the carcass in the tire width direction in the sidewall portion. In order to achieve the above object, a pneumatic tire including side reinforcing rubber having a crescent-shaped cross section and a bead filler disposed outside the bead core of the sidewall portion in the tire radial direction was investigated.
As a result, we found that by incorporating specific polyphenols and aldehydes into the adhesive composition used to coat organic fiber cords, high adhesive strength can be achieved even when resorcinol is not used. It has been found that rolling resistance can be improved by optimizing the nitrogen adsorption specific surface area and dibutyl phthalate oil absorption of the carbon black contained.

That is, the pneumatic tire of the present invention includes a carcass consisting of one or more carcass plies extending from a pair of bead portions to a tread portion via a sidewall portion, and a carcass disposed inside the carcass in the tire width direction in the sidewall portion. A pneumatic tire comprising: a pair of side reinforcing rubber having a crescent-shaped cross section, and a bead filler disposed on the outer side in the tire radial direction of the bead core of the sidewall portion,
The pneumatic tire has an organic fiber cord coated with an adhesive composition containing polyphenols and aldehydes,
At least one of the side reinforcing rubber and the bead filler contains a rubber component and carbon black, and the carbon black has a nitrogen adsorption specific surface area of 5 to 40 m ² /g and an oil absorption amount of dibutyl phthalate. It is characterized by being 100 to 180 mL/100 g.
With the above configuration, the adhesive composition coated on the organic fiber cord does not contain resorcin, and in addition to having less environmental impact, it is possible to achieve excellent rolling resistance.

Further, in the pneumatic tire of the present invention, at least one of the side reinforcing rubber and the bead filler further includes a vulcanizing agent and a vulcanization accelerator, and the vulcanization accelerator is a thiuram-based vulcanization agent. It is preferable to contain a vulcanization accelerator, and it is more preferable to further contain a sulfenamide vulcanization accelerator. This is because rolling resistance and durability can be further improved.

Furthermore, in the pneumatic tire of the present invention, it is preferable that the adhesive composition further contains rubber latex. This is because better adhesion between the organic fiber and the rubber member can be obtained.

Furthermore, in the pneumatic tire of the present invention, it is preferable that the adhesive composition further contains an isocyanate compound, and it is more preferable that the isocyanate compound is an aromatic compound containing a (blocked) isocyanate group. This is because better adhesion between the organic fiber and the rubber member can be obtained.

Moreover, in the pneumatic tire of the present invention, it is preferable that the polyphenols have three or more hydroxyl groups. This is because better adhesion between the organic fiber and the rubber member can be obtained.

Furthermore, in the pneumatic tire of the present invention, the aldehyde preferably has two or more aldehyde groups. This is because better adhesion between the organic fiber and the rubber member can be obtained.

Further, in the pneumatic tire of the present invention, it is preferable that the organic fiber cord is used at least in the carcass ply and/or the belt reinforcing layer. This is because, in addition to having less burden on the environment, it also has excellent durability.

Furthermore, in the pneumatic tire of the present invention, it is preferable that the organic fiber cord is a hybrid cord formed by twisting filaments made of two types of organic fibers, and the two types of organic fibers constituting the hybrid cord are More preferably, the material is selected from the group consisting of , rayon, lyocell, polyester, nylon and polykentone. This is because it is possible to achieve a high level of both low-speed and high-temperature handling stability and high-speed durability.

According to the present invention, it is an object of the present invention to provide a pneumatic tire in which an adhesive composition coated on an organic fiber cord does not contain resorcinol, has a low load on the environment, and has excellent rolling resistance. I can do it.

1 is a cross section along the tire axial direction of a tire half of an embodiment of the pneumatic tire of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the pneumatic tire of the present invention will be described with reference to the drawings as necessary.
As shown in FIG. 1, the pneumatic tire of the present invention includes a tread portion 1, a pair of sidewall portions 2 (only one side shown) extending inward in the tire radial direction from each side of the tread portion 1, and a pair of sidewall portions 2 (only one side shown). It consists of a pair of bead portions 3 (only one side is shown) that are continuous on the inside of the sidewall portion 2 in the tire radial direction.

The pneumatic tire shown in FIG. 1 also includes a bead core 6 embedded in a pair of bead portions 3, and a carcass 4 consisting of one or more carcass plies extending from the pair of bead portions 3 via the sidewall portion 2 to the tread portion 1. , a bead filler 7 placed on the outside of the bead core 6 in the tire radial direction, a belt 5 placed on the outside of the tire radial direction in the crown area of the carcass 4, and a bead filler 7 placed on the outside of the belt 5 in the tire radial direction, tread rubber 11 forming the tread rubber 11.
In the pneumatic tire shown in FIG. 1, the carcass 4, which can have a radial structure with organic fiber cords extending in the radial direction, has a toroidal shape from the bead portion 3 to the tread portion 1 via the sidewall portion 2. The main body part 4a is anchored to the bead part 3 by a folded part 4b which is continuous with the main body part 4a extending in the direction of the main body part 4a and is folded back around the bead core 6.

Further, the belt 5 located on the outside of the carcass 4 in the tire radial direction is, for example, as shown in FIG. A belt layer 50 is provided in which an inner belt layer and an outer belt layer each having a cord extending in a direction intersecting the cord of the inner belt layer are sequentially arranged outward in the tire radial direction, A belt reinforcing layer 51 made of cords extending substantially in the circumferential direction of the tire may be arranged on the outside of the belt layer 50 in the tire radial direction, but the structure, arrangement area, number of layers, etc. of the belt layer etc. can be changed as necessary.

Furthermore, the pneumatic tire of FIG. A pair of side reinforcing rubbers 9 (only one side is shown) are provided on the inside in the direction.
As shown in FIG. 1, the thickness of the side reinforcing rubber 9 gradually decreases toward the inner and outer sides of the tire in the radial direction in the illustrated cross section along the tire axial direction, and the thickness gradually decreases toward the outer side in the tire axial direction. It is shaped like a crescent moon by convexly curving it.
By arranging the side reinforcing rubber 9 in this way, even when the internal pressure of the tire decreases due to a puncture or the like, the side reinforcing rubber 9 contributes to supporting the vehicle weight, making it possible to safely travel a certain distance. become.

<Organic fiber cord coated with adhesive composition>
The pneumatic tire of the present invention has an organic fiber cord coated with an adhesive composition containing polyphenols and aldehydes.
The adhesive composition used to coat organic fiber cords used in carcass plies, belts, etc. contains specific polyphenols and aldehydes, so resorcinol is not used in consideration of the environmental impact. Good adhesion can be achieved even if

(Polyphenols)
The adhesive composition contains polyphenols as a resin component. By including polyphenols in the adhesive composition, the adhesiveness of the resin composition can be improved.
Here, the polyphenols are water-soluble polyphenols and are not limited as long as they are polyphenols other than resorcinol, and the number of aromatic rings and the number of hydroxyl groups can be selected as appropriate. can.

Further, from the viewpoint of realizing better adhesiveness, the polyphenols preferably have two or more hydroxyl groups, and more preferably three or more hydroxyl groups. By containing three or more hydroxyl groups, the polyphenol or the condensation product of the polyphenol is dissolved in water by the adhesive composition liquid containing water, so that it can be uniformly distributed in the adhesive composition, resulting in better adhesive properties. realizable.
Furthermore, when the polyphenol is a polyphenol containing a plurality of (two or more) aromatic rings, two or three hydroxyl groups are present in each of the aromatic rings at the ortho, meta, or para positions.

モリン（２’，４’，３，５，７－ペンタヒドロキシフラボン）：

フロログルシド（２，４，６，３，’５’－ビフェニルペントール）：

Examples of the above-mentioned polyphenols having three or more hydroxyl groups include the following polyphenols.
Phloroglucinol:

Morin (2',4',3,5,7-pentahydroxyflavone):

Phlorogluside (2,4,6,3,'5'-biphenylpentol):

(Aldehydes)
The adhesive composition contains aldehydes as a resin component in addition to the polyphenols mentioned above. By containing aldehydes in the adhesive composition, high adhesiveness can be achieved together with the above-mentioned polyphenols.
Here, the aldehydes are not particularly limited and can be appropriately selected depending on the required performance. In addition, in the present invention, derivatives of aldehydes whose generation source is the above-mentioned aldehydes are also included in the scope of aldehydes.

Examples of the aldehydes include monoaldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, propionaldehyde, chloral, butyraldehyde, caproaldehyde, allylaldehyde, glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, and azylaldehyde. Examples include aliphatic dialdehydes such as polyaldehyde, aldehydes having an aromatic ring, and dialdehyde starch. These aldehydes may be used alone or in combination.
Among these, the aldehydes preferably contain aldehydes having an aromatic ring. This is because better adhesion can be obtained.
Note that the aldehydes preferably do not contain formaldehyde. In addition, in the present invention, "formaldehyde-free" means that the mass content of formaldehyde based on the total mass of aldehydes is less than 0.5 mass%.

Further, the aldehydes having an aromatic ring are aromatic aldehydes that contain at least one aromatic ring and have at least one aldehyde group in one molecule. The aldehydes having an aromatic ring have a low environmental impact, and form a relatively inexpensive resin having excellent mechanical strength, electrical insulation, acid resistance, water resistance, heat resistance, etc. I can do it.

Moreover, from the viewpoint of achieving better adhesiveness, the aldehyde having an aromatic ring preferably has two or more aldehyde groups. By crosslinking and condensing the aldehydes with a plurality of aldehyde groups, the degree of crosslinking of the thermosetting resin can be increased, so that adhesiveness can be further improved.
Furthermore, when the aldehydes have two or more aldehyde groups, it is more preferable that two or more aldehyde groups exist in one aromatic ring. Note that each aldehyde group can be present in the ortho, meta, or para position in one aromatic ring.

Examples of such aldehydes include 1,2-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,4-benzenedicarbaldehyde, 1,4-benzenedicarbaldehyde, and 2-hydroxy Examples include benzene-1,3,5-tricarbaldehyde and mixtures of these compounds.

Among these, it is preferable to use at least 1,4-benzenedicarbaldehyde as the aromatic ring-containing aldehyde from the viewpoint of achieving better adhesion.

（式中、Ｘは、Ｏを含み；Ｒは、－Ｈまたは－ＣＨＯを示す。） Furthermore, the aldehydes having an aromatic ring include not only those having a benzene ring but also heteroaromatic compounds.
Examples of the aldehydes that are the heteroaromatic compounds include aldehydes having a furan ring as shown below.

(In the formula, X includes O; R represents -H or -CHO.)

（式中、Ｒは、－Ｈまたは－ＣＨＯ；Ｒ１、Ｒ２及びＲ３は、それぞれ、アルキル、アリール、アリールアルキル、アルキルアリール又はシクロアルキル基を示す。） Examples of the aldehydes having a furan ring include the following compounds.

(In the formula, R is -H or -CHO; R1, R2 and R3 each represent an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.)

In addition, in the adhesive composition, the polyphenols and the aldehydes are in a condensed state, and the mass ratio of the polyphenols to the aldehydes having an aromatic ring (content of aldehydes having an aromatic ring/ The content of polyphenols) is preferably 0.1 or more and 3 or less, more preferably 0.25 or more and 2.5 or less. This is because a condensation reaction occurs between the polyphenols and the aldehydes having an aromatic ring, and the resulting resin has more suitable hardness and adhesive properties.

Further, the total content of the polyphenols and the aldehydes having an aromatic ring in the adhesive composition is preferably 3 to 30% by mass, more preferably 5 to 25% by mass. . This is because better adhesion can be ensured without deteriorating workability or the like.
Note that the mass ratio and total content of the polyphenols and the aromatic ring-containing aldehydes are the mass (solid content ratio) of the dry product.

(Isocyanate compound)
It is preferable that the adhesive composition further contains an isocyanate compound in addition to the above-mentioned polyphenols and aldehydes. The synergistic effect with polyphenols and aldehydes can greatly enhance the adhesive properties of the adhesive composition.

Here, the isocyanate compound is a compound that has the effect of promoting the adhesion of the adhesive composition to a resin material (for example, a phenol/aldehyde resin made by condensing polyphenols and aldehydes) that is an adherend. , is a compound having an isocyanate group as a polar functional group.

The type of the isocyanate compound is not particularly limited, but is preferably an aromatic compound containing a (blocked) isocyanate group from the viewpoint of further improving adhesiveness. When the isocyanate compound is included in the adhesive composition of the present invention, the blocked isocyanate group-containing aromatic is distributed near the interface between the adherend fiber and the adhesive composition, resulting in an adhesion promoting effect. This function and effect makes it possible to improve the adhesion with the organic cord.
The (blocked) isocyanate group-containing aromatic compound is an aromatic compound having a (blocked) isocyanate group. In addition, "(blocked) isocyanate group" means a blocked isocyanate group or an isocyanate group, and in addition to the isocyanate group, a blocked isocyanate group generated by reaction with a blocking agent for the isocyanate group, and a block for the isocyanate group. It includes isocyanate groups that have not reacted with the blocking agent, or isocyanate groups that are generated by dissociation of the blocking agent from blocked isocyanate groups.

Further, the (blocked) isocyanate group-containing aromatic compound preferably includes a molecular structure in which aromatics are bonded by alkylene chains, and more preferably includes a molecular structure in which aromatics are bonded by methylene chains. Examples of molecular structures in which aromatics are bonded with alkylene chains include those found in diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate, and condensates of phenols and formaldehyde.

The (blocked) isocyanate group-containing aromatic compound is, for example, a compound containing an aromatic polyisocyanate and a heat-dissociable blocking agent, diphenylmethane diisocyanate, or an aromatic polyisocyanate blocked with a heat-dissociable blocking agent. Water-dispersible compounds, aqueous urethane compounds, etc. containing such components can be mentioned.

Preferred examples of the compound containing the aromatic polyisocyanate and a thermally dissociable blocking agent include blocked isocyanate compounds containing diphenylmethane diisocyanate and a known isocyanate blocking agent. The water-dispersible compound containing a component obtained by blocking the diphenylmethane diisocyanate or aromatic polyisocyanate with a thermally dissociable blocking agent includes diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate, and a known blocking agent that blocks isocyanate groups. Examples include reaction products blocked with . Specifically, commercially available blocked drugs such as Elastron BN69 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Elastron BN77 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and Meikanate TP-10 (manufactured by Meisei Chemical Industry Co., Ltd.) are used. Polyisocyanate compounds can be used.

The aqueous urethane compound comprises an organic polyisocyanate compound (α) containing a molecular structure in which aromatics are bonded by alkylene chains, preferably a molecular structure in which aromatics are bonded by methylene chains, and a compound (α) having a plurality of active hydrogens. It is obtained by reacting β) with a thermally dissociable blocking agent (γ) for isocyanate groups. In addition, due to its flexible molecular structure, the water-based urethane compound (F) not only acts as an adhesion improver, but also acts as a flexible crosslinking agent to prevent the adhesive from fluidizing at high temperatures. have
Note that "water-based" indicates water-soluble or water-dispersible, and "water-soluble" does not necessarily mean complete water-solubility, but refers to partially water-soluble or adhesive composition. It means a substance that does not undergo phase separation in an aqueous solution.

（式中、Ａは芳香族類がアルキレン鎖で結合された分子構造を含有する有機ポリイソシアネート化合物（α）の活性水素が脱離した残基を示し、Ｙはイソシアネート基に対する熱解離性ブロック化剤（γ）の活性水素が脱離した残基を示し、Ｚは化合物（δ）の活性水素が脱離した残基を示し、Ｘは複数の活性水素を有する化合物（β）の活性水素が脱離した残基であり、ｎは２～４の整数であり、ｐ＋ｍは２～４の整数（ｍ≧０．２５）である。）で表される水性ウレタン化合物が好ましい。 Here, as the aqueous urethane compound (F), for example, the following general formula (I):

(In the formula, A represents a residue from which active hydrogen has been removed from an organic polyisocyanate compound (α) containing a molecular structure in which aromatics are bonded via an alkylene chain, and Y represents a thermally dissociable block for the isocyanate group. Z indicates the residue from which the active hydrogen of the agent (γ) has been eliminated, Z indicates the residue from which the active hydrogen of the compound (δ) has been eliminated, and X represents the residue from which the active hydrogen of the compound (β) having multiple active hydrogens has been eliminated. Preferred is an aqueous urethane compound represented by the following formula, where n is an integer of 2 to 4, and p+m is an integer of 2 to 4 (m≧0.25).

In addition, examples of the organic polyisocyanate compound (α) containing a molecular structure in which aromatics are bonded through an alkylene chain include methylene diphenyl polyisocyanate, polymethylene polyphenyl polyisocyanate, and the like.
Further, the compound (β) having a plurality of active hydrogens preferably has 2 to 4 active hydrogens and has an average molecular weight of 5,000 or less. Such compounds (β) include (i) polyhydric alcohols having 2 to 4 hydroxyl groups, (ii) polyhydric amines having 2 to 4 primary and/or secondary amino groups, (iii) amino alcohols having 2 to 4 primary and/or secondary amino groups and hydroxyl groups; (iv) polyester polyols having 2 to 4 hydroxyl groups; (v) 2 to 4 hydroxyl groups; Polybutadiene polyols having hydroxyl groups and copolymers of these with other vinyl monomers, (vi) polychloroprene polyols having 2 to 4 hydroxyl groups and copolymers of these with other vinyl monomers, (vii) Polyether polyols having 2 to 4 hydroxyl groups, including C2 to C4 alkylene oxide polyadducts of polyhydric amines, polyhydric phenols and amino alcohols, and C2 to C4 polyhydric alcohols of C3 or higher. Examples include alkylene oxide polyadducts, C2 to C4 alkylene oxide copolymers, and C3 to C4 alkylene oxide polymers.
Furthermore, the thermally dissociable blocking agent (γ) for isocyanate groups is a compound capable of releasing isocyanate groups by heat treatment, and examples thereof include known isocyanate blocking agents.
Furthermore, the compound (δ) is a compound having at least one active hydrogen and an anionic and/or nonionic hydrophilic group. Examples of compounds having at least one active hydrogen and anionic hydrophilic group include aminosulfonic acids such as taurine, N-methyltaurine, N-butyltaurine, and sulfanilic acid, and aminocarboxylic acids such as glycine and alanine. It will be done. On the other hand, examples of the compound having at least one active hydrogen and a nonionic hydrophilic group include compounds having a hydrophilic polyether chain.

Further, the content of the isocyanate compound in the adhesive composition is not particularly limited, but from the viewpoint of ensuring more reliably excellent adhesiveness, it is preferably in the range of 5 to 65% by mass, and 10% by mass. More preferably, it is 45% by mass.
Note that the content of the isocyanate compound is the mass (solid content ratio) of the dry product.

(rubber latex)
In addition to the above-mentioned polyphenols, aldehydes, and isocyanate compounds, the adhesive composition may substantially further include rubber latex. This is because the adhesiveness with the rubber member can be further improved.

Here, the rubber latex is not particularly limited, and in addition to natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene - Synthetic rubbers such as diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitriole-butadiene rubber (NBR), and vinylpyridine-styrene-butadiene copolymer rubber (Vp) can be used. These rubber components may be used alone or in a blend of two or more.

Further, it is preferable that the rubber latex is mixed with the phenols and the aldehydes before blending with the isocyanate compound.
Furthermore, the content of the rubber latex in the adhesive composition is preferably 20 to 70% by mass, more preferably 25 to 60% by mass.

The method for producing the adhesive composition for organic fiber cords is not particularly limited, but includes, for example, a method of mixing and aging raw materials such as the polyphenols, aldehydes, and rubber latex; Examples include a method in which the rubber latex and the aldehydes are mixed and aged, and then the rubber latex is further added and aged. Moreover, when the isocyanate compound is included, the isocyanate compound can be added after the rubber latex is added and aged.
The composition, content, etc. of the polycyclic aromatic hydrocarbon, the aldehydes, the rubber latex, and the isocyanate compound are the same as those explained in the adhesive composition described above.

(Rubber-organic fiber cord composite)
Here, the pneumatic tire of the present invention has an organic fiber cord coated with the adhesive composition, and the organic fiber cord coated with the adhesive composition is combined with a rubber member such as coated rubber. They are adhered to form a rubber-organic fiber cord composite.
Since the obtained rubber-organic fiber cord composite uses the adhesive composition described above, the load on the environment is small.

Here, in the pneumatic tire of the present invention, the rubber-organic fiber cord composite is, for example, as shown in FIG. It can be used as a surrounding reinforcing layer (not shown) or the like.
Among these, the rubber-organic fiber cord composite is preferably used for a carcass ply and/or a belt reinforcing layer. This is because the environmental load of the organic fiber cord coated with the adhesive composition can be reduced, and the excellent adhesiveness between the organic fiber and the rubber member can be more effectively exhibited.

In the rubber-organic fiber cord composite, the adhesive composition only needs to cover at least a portion of the organic fiber cord, but from the viewpoint of further improving the adhesiveness between the rubber and the organic fiber cord, Preferably, the entire surface of the organic fiber cord is coated with the adhesive composition.

Further, the material of the organic fiber cord is not particularly limited, and can be appropriately selected depending on the purpose. For example, synthetic resins such as polyester, aliphatic polyamide fiber cords such as 6-nylon, 6,6-nylon, and 4,6-nylon, polyketone fiber cords, and aromatic polyamide fiber cords such as paraphenylene terephthalamide. Can be used for textile materials.

In addition, the organic fiber cord should be a hybrid cord made by twisting filaments made of two types of organic fibers, from the viewpoint of achieving both low-speed and high-temperature handling stability and high-speed durability at a high level. is preferred.

Furthermore, from the viewpoint of further improving high-speed durability, the hybrid cord preferably has a heat shrinkage stress (cN/dtex) of 0.20 cN/dtex or more at 177°C, and 0.25 to 0.40 cN/dtex. More preferably, it is within the range of dtex.

Furthermore, from the viewpoint of further improving handling stability at low speeds and high temperatures, the hybrid cord has a tensile modulus of elasticity of 60 cN/dtex or less at 1% strain at 25° C., particularly 35 to 50 cN/dtex. It is preferable that the tensile modulus at 3% strain at 25° C. is 30 cN/dtex or more, particularly 45 to 70 cN/dtex.

The two types of organic fibers used in the hybrid cord are not particularly limited, but organic fibers with high rigidity include rayon and lyocell, and organic fibers with high heat shrinkage include polyester, Examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), nylon, polyketone (PK), and the like. More preferably, a combination of rayon or lyocell and nylon can be used.
In addition, as a method of adjusting the heat shrinkage stress and tensile modulus of the hybrid cord using these organic fibers, there is a method of controlling the tension during dipping treatment, for example, performing dipping treatment while applying high tension. With this, the value of the heat shrinkage stress of the cord can be increased. That is, although each organic fiber has its own physical property value range, by controlling the dipping treatment conditions, the physical property values can be adjusted within that range to obtain a hybrid cord having desired physical properties.

<Side reinforcement rubber, bead filler>
In the pneumatic tire of the present invention, at least one of the side reinforcing rubber 9 and the bead filler 7 contains a rubber component and carbon black, and the carbon black has a nitrogen adsorption specific surface area of 5 to 40 m ^{2 .} /g, and the dibutyl phthalate oil absorption amount is 100 to 180 mL/100 g.
By containing carbon black with a large particle size and a high structure in the side reinforcing rubber 9 and the bead filler 7, excellent rolling resistance can be achieved and the durability of the tire can also be maintained at a high level.

(rubber component)
The rubber component contained in the side reinforcing rubber 9 and/or the bead filler 7 is not particularly limited. For example, it can contain diene rubber (natural rubber (NR), synthetic diene rubber).

The synthetic diene rubbers include polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butadiene-isoprene copolymer rubber (BIR), and styrene-isoprene copolymer rubber. (SIR), styrene-butadiene-isoprene copolymer rubber (SBIR), and the like.
The diene rubber is preferably natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, or polybutadiene rubber, and more preferably natural rubber or polybutadiene rubber. The diene rubbers may be used alone or in combination of two or more.

Further, the rubber component may be modified or unmodified, and when two or more kinds of rubber components are used, an unmodified rubber component and a modified rubber component may be mixed and used. .
Furthermore, the rubber component may contain a diene rubber or a non-diene rubber, but from the viewpoint of obtaining a vulcanized rubber having a network structure with excellent softening resistance and mechanical strength at high temperatures, It is preferable that it contains at least a diene rubber, and more preferably it consists of a diene rubber.
Furthermore, the diene rubber may be either natural rubber or synthetic diene rubber, or both may be used, but from the viewpoint of improving fracture properties such as tensile strength and elongation at break, It is preferable to use natural rubber and synthetic diene rubber together.

Further, the diene rubber may be either natural rubber or synthetic diene rubber, or both may be used, but at least one of the side reinforcing rubber 9 and the bead filler 7 may be used. From the viewpoint of improving fracture properties such as tensile strength and elongation at break, and improving durability, it is preferable to use the natural rubber and the synthetic diene rubber in combination.
Further, from the viewpoint of further improving the durability of at least one of the side reinforcing rubber 9 and the bead filler 7, the content of natural rubber in the rubber component is 20 to 99% by mass, and the synthetic diene rubber is preferably 1 to 80% by mass, the content of natural rubber is 20 to 99% by mass, more preferably the content of polybutadiene rubber is 1 to 80% by mass, and the content of natural rubber is 30 to 70% by mass. It is more preferable that the content of polybutadiene rubber is 30 to 70% by weight, the content of natural rubber is 35 to 65% by weight, and it is even more preferable that the content of polybutadiene rubber is 35 to 65% by weight.
Note that the rubber component may contain non-diene rubber as long as the effects of the present invention are not impaired.

From the viewpoint of improving the low heat generation property of the vulcanized rubber, the rubber component is preferably a rubber containing a modified group (sometimes referred to as a modified rubber), and more preferably a synthetic rubber containing a modified group. preferable.
From the viewpoint of improving the reinforcing properties of the side reinforcing rubber, the rubber composition contains a filler, and in order to enhance the interaction with the filler (especially carbon black), the rubber component contains a modified group. It is preferable that the synthetic rubber includes polybutadiene rubber containing a modified group (modified polybutadiene rubber).
As will be described later, since the side reinforcing rubber 9 and/or the bead filler 7 contain at least carbon black as a filler, the modified polybutadiene rubber is a modified polybutadiene rubber having at least one functional group that interacts with carbon black. Butadiene rubber is preferred.
The functional group that interacts with carbon black is preferably a functional group that has affinity with carbon black, and is specifically selected from the group consisting of a tin-containing functional group, an oxygen-containing functional group, and a nitrogen-containing functional group. Preferably, it is at least one type.

When the modified polybutadiene rubber has at least one functional group selected from the group consisting of a tin-containing functional group, a silicon-containing functional group, and a nitrogen-containing functional group, the modified polybutadiene rubber has a tin-containing functional group, a silicon-containing functional group, and a nitrogen-containing functional group. It is preferable that the material be modified with a modifier such as a silicon-containing compound, a silicon-containing compound, or a nitrogen-containing compound to introduce a tin-containing functional group, a silicon-containing functional group, a nitrogen-containing functional group, or the like.
When modifying the polymerization active site of butadiene rubber with a modifier, the modifier used is preferably a nitrogen-containing compound, a silicon-containing compound, or a tin-containing compound. In this case, a nitrogen-containing functional group, a silicon-containing functional group or a tin-containing functional group can be introduced by a modification reaction.
Such a modifying functional group may be present at any one of the polymerization initiation terminal, the main chain, and the polymerization active terminal of the polybutadiene.

The nitrogen-containing compound that can be used as the modifier preferably has a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, or pyridyl group. Nitrogen-containing compounds suitable as the modifier include isocyanate compounds such as diphenylmethane diisocyanate, crude MDI, trimethylhexamethylene diisocyanate, tolylene diisocyanate, 4-(dimethylamino)benzophenone, 4-(diethylamino)benzophenone, 4-dimethylamino Examples include benzylideneaniline, 4-dimethylaminobenzylidenebutylamine, dimethylimidazolidinone, and N-methylpyrrolidonehexamethyleneimine.

Further, silicon-containing compounds that can be used as the modifier include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, N-(1-methylpropylidene)-3-(trimethoxysilane), and N-(1-methylpropylidene)-3-(trimethoxysilane). ethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(3-triethoxysilylpropyl)-4,5-dihydro Imidazole, 3-methacryloyloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-triethoxysilylpropylsuccinic anhydride, 3-(1-hexamethyleneimino)propyl(triethoxy)silane, (1- Hexamethyleneimino)methyl(trimethoxy)silane, 3-diethylaminopropyl(triethoxy)silane, 3-dimethylaminopropyl(triethoxy)silane, 2-(trimethoxysilylethyl)pyridine, 2-(triethoxysilylethyl)pyridine, 2 -Cyanoethyltriethoxysilane, tetraethoxysilane and the like. These silicon-containing compounds may be used alone or in combination of two or more. Moreover, a partial condensate of the silicon-containing compound can also be used.

Furthermore, as the above-mentioned modifier, the following formula (I):
R ¹ _a ZX _b (I)
[In the formula, R ¹ each independently consists of an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Z is tin or silicon; X is each independently chlorine or bromine; Also preferred are the modifiers represented. Note that the modified polybutadiene rubber obtained by modification with the modifier of formula (I) has at least one type of tin-carbon bond or silicon-carbon bond.

Specific examples of R ¹ in formula (I) include methyl group, ethyl group, n-butyl group, neophyl group, cyclohexyl group, n-octyl group, and 2-ethylhexyl group. Further, as the modifier of formula (I), specifically, SnCl ₄ , R ¹ SnCl ₃ , R ¹ ₂ SnCl ₂ , R ¹ ₃ SnCl, SiCl ₄ , R ¹ SiCl ₃ , R ¹ ₂ SiCl ₂ , R ¹ ₃ SiCl and the like are preferred, and SnCl ₄ and SiCl ₄ are particularly preferred.

Among the above, the modified polybutadiene rubber is preferably a modified polybutadiene rubber having a nitrogen-containing functional group, and more preferably an amine-modified polybutadiene rubber, from the viewpoint of reducing heat generation of the vulcanized rubber and extending its durable life. preferable.

In the amine-modified polybutadiene rubber, the amine functional group for modification is preferably a primary amino group or a secondary amino group, and a primary amino group protected with a releasable group or a primary amino group protected with a releasable group. It is more preferable to introduce a secondary amino group, and even more preferable to introduce a functional group containing a silicon atom in addition to these amino groups.
An example of a primary amino group protected with a removable group (also referred to as a protected primary amino group) is an N,N-bis(trimethylsilyl)amino group; An example of a secondary amino group protected by is an N,N-(trimethylsilyl)alkylamino group. This N,N-(trimethylsilyl)alkylamino group-containing group may be either an acyclic residue or a cyclic residue.
Among the above amine-modified polybutadiene rubbers, primary amine-modified polybutadiene rubbers modified with protected primary amino groups are more preferred.
Examples of the functional group containing a silicon atom include a hydrocarbyloxysilyl group and/or a silanol group in which a hydrocarbyloxy group and/or a hydroxy group are bonded to a silicon atom.
Such a modifying functional group preferably has an amino group protected with a removable group and a silicon atom to which a hydrocarbyloxy group and a hydroxyl group are bonded to the polymerization end of the butadiene rubber, more preferably to the same polymerization active end. 1 or more (for example, 1 or 2).

In order to modify the active end of butadiene rubber by reacting with a protected primary amine, it is preferable that at least 10% of the polymer chains of the butadiene rubber have living or pseudo-living properties. Such living polymerization reactions include anionic polymerization of a conjugated diene compound alone or a conjugated diene compound and an aromatic vinyl compound in an organic solvent using an organic alkali metal compound as an initiator; Among these, examples include coordination anionic polymerization of a conjugated diene compound alone or a conjugated diene compound and an aromatic vinyl compound using a catalyst containing a lanthanum series rare earth element compound. The former is preferable since it is possible to obtain a conjugated diene moiety with a higher vinyl bond content than the latter. By increasing the amount of vinyl bonds, the heat resistance of the vulcanized rubber can be improved.

Here, as the organic alkali metal compound used as an initiator for anionic polymerization, an organic lithium compound is preferable. The organic lithium compound is not particularly limited, but hydrocarbyllithium and lithium amide compounds are preferably used, and when the former hydrocarbyllithium is used, it has a hydrocarbyl group at the polymerization initiation terminal, and the other terminal has a polymerization active group. butadiene rubber is obtained. When the latter lithium amide compound is used, a butadiene rubber having a nitrogen-containing group at the polymerization initiation end and a polymerization active site at the other end is obtained.

The hydrocarbyllithium is preferably one having a hydrocarbyl group having 2 to 20 carbon atoms, such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-octyllithium, n-decyllithium. Examples include lithium, phenyllithium, 2-naphthyllithium, 2-butylphenyllithium, 4-phenylbutyllithium, cyclohexyllithium, cyclobentyllithium, reaction products of diisopropenylbenzene and butyllithium, etc. Among these, n-butyllithium is particularly preferred.

On the other hand, examples of lithium amide compounds include lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, and lithium dipropylamide. Heptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, etc. can be mentioned. Among these, cyclic lithium amides such as lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, and lithium dodecamethyleneimide are preferred from the viewpoint of interaction effect with carbon black and polymerization initiation ability. Particularly suitable are lithium hexamethyleneimide and lithium pyrrolidide.
Generally, these lithium amide compounds can be used in the polymerization by being prepared in advance from a secondary amine and a lithium compound, but they can also be prepared in-situ. Further, the amount of the polymerization initiator used is preferably selected within the range of 0.2 to 20 mmol per 100 g of monomer.

The method for producing butadiene rubber by anionic polymerization using the organolithium compound as a polymerization initiator is not particularly limited, and conventionally known methods can be used.
Specifically, the conjugated diene compound or the conjugated diene compound and the aromatic vinyl compound are mixed in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic, or aromatic hydrocarbon compound. By anionically polymerizing a lithium compound as a polymerization initiator, optionally in the presence of a used randomizer, a butadiene rubber having the desired active end can be obtained.
In addition, when an organolithium compound is used as a polymerization initiator, compared to the case where a catalyst containing the lanthanum series rare earth element compound mentioned above is used, not only butadiene rubber having an active end but also a conjugated diene compound having an active end can be produced. Copolymers of aromatic vinyl compounds and aromatic vinyl compounds can also be obtained efficiently.

The hydrocarbon solvent preferably has 3 to 8 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2 -butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.
Further, the monomer concentration in the solvent is preferably 5 to 50% by weight, more preferably 10 to 30% by weight. When copolymerizing a conjugated diene compound and an aromatic vinyl compound, the content of the aromatic vinyl compound in the charged monomer mixture is preferably 55% by mass or less.

In the present invention, a primary amine-modified polybutadiene rubber is produced by reacting a protected primary amine compound as a modifier with the active end of the butadiene rubber having an active end obtained as described above. By reacting a protected secondary amine compound, a secondary amine-modified polybutadiene rubber can be produced. As the protected primary amine compound, an alkoxysilane compound having a protected primary amino group is suitable, and as the protected secondary amine compound, an alkoxysilane compound having a protected secondary amino group is suitable. is suitable.

Examples of the alkoxysilane compound having a protected primary amino group used as a modifier for obtaining the amine-modified polybutadiene rubber include N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2, 2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl) Aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane and N , N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, etc., preferably N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, etc. Silane or 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane.

Further, as the modifier for obtaining the amine-modified polybutadiene rubber, N-methyl-N-trimethylsilylaminopropyl(methyl)dimethoxysilane, N-methyl-N-trimethylsilylaminopropyl(methyl)diethoxysilane, N-trimethylsilyl (hexamethyleneimin-2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(hexamethyleneimin-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(pyrrolidin-2-yl)propyl(methyl) Dimethoxysilane, N-trimethylsilyl(pyrrolidin-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(piperidin-2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(piperidin-2-yl)propyl( methyl)diethoxysilane, N-trimethylsilyl(imidazol-2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(imidazol-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(4,5-dihydro) Alkoxysilane compounds having a protected secondary amino group such as imidazol-5-yl)propyl(methyl)dimethoxysilane and N-trimethylsilyl(4,5-dihydroimidazol-5-yl)propyl(methyl)diethoxysilane; N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene -3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene) -3-(triethoxysilyl)-1-propanamine, N-(cyclohexylidene)-3-(triethoxysilyl)-1-propanamine and other alkoxysilane compounds having an imino group; 3-dimethylaminopropyl ( triethoxy)silane, 3-dimethylaminopropyl(trimethoxy)silane, 3-diethylaminopropyl(triethoxy)silane, 3-diethylaminopropyl(trimethoxy)silane, 2-dimethylaminoethyl(triethoxy)silane, 2-dimethylaminoethyl(trimethoxy) Also included are alkoxysilane compounds having an amino group such as silane, 3-dimethylaminopropyl(diethoxy)methylsilane, and 3-dibutylaminopropyl(triethoxy)silane.
These modifiers may be used alone or in combination of two or more. Moreover, this modifier may be a partial condensate.
Here, the partial condensate refers to a product in which a part (but not all) of the modifier SiOR (R is an alkyl group, etc.) becomes an SiOSi bond through condensation.

In the modification reaction using the modifier, the amount of the modifier used is preferably 0.5 to 200 mmol/kg of butadiene rubber. The amount used is more preferably 1 to 100 mmol/kg of butadiene rubber, particularly preferably 2 to 50 mmol/kg of butadiene rubber. Here, butadiene rubber means the mass of butadiene rubber that does not contain additives such as anti-aging agents added during or after production. By controlling the amount of the modifier used within the above range, the filler, especially carbon black, will have excellent dispersibility, and the fracture resistance and low heat build-up of the vulcanized rubber will be improved.
The method of adding the modifier is not particularly limited, and examples include a method of adding it all at once, a method of adding it in parts, a method of adding it continuously, etc. preferable.
In addition, the modifier can be bonded to any of the polymer main chain or side chain in addition to the polymerization start end and polymerization end end, but it is possible to suppress energy dissipation from the polymer end and improve low heat build-up. Therefore, it is preferable that it is introduced at the polymerization start end or the polymerization end end.

Further, in order to promote the condensation reaction involving the alkoxysilane compound having a protected primary amino group used as the modifier, it is preferable to use a condensation promoter.
Such condensation accelerators include compounds containing a tertiary amino group, or compounds from Groups 3, 4, 5, 12, 13, 14 and 15 of the periodic table (long period type). An organic compound containing one or more of the elements belonging to any of the following can be used. Further, as a condensation accelerator, an alkoxide or a carboxyl group containing at least one metal selected from the group consisting of titanium (Ti), zirconium (Zr), bismuth (Bi), aluminum (Al), and tin (Sn) is used. An acid salt or an acetylacetonate complex salt is preferred.
Although the condensation accelerator used here can be added before the modification reaction, it is preferably added to the modification reaction system during and/or after the modification reaction is completed. When added before the modification reaction, a direct reaction with the active end occurs, and a hydrocarbyloxy group having a protected primary amino group may not be introduced into the active end.
The time of addition of the condensation accelerator is usually 5 minutes to 5 hours after the start of the modification reaction, preferably 15 minutes to 1 hour after the start of the modification reaction.

Specific examples of the condensation accelerator include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetra-n-butoxytitanium oligomer, and tetra-n-butoxytitanium. sec-butoxytitanium, tetra-tert-butoxytitanium, tetra(2-ethylhexyl)titanium, bis(octanediolate)bis(2-ethylhexyl)titanium, tetra(octanediolate)titanium, titanium lactate, titanium dipropoxybis( titanium dibutoxy stearate, titanium tripropoxy stearate, titanium ethylhexyldiolate, titanium tripropoxy acetylacetonate, titanium dipropoxy bis (acetylacetonate) , titanium tripropoxyethylacetoacetate, titanium propoxyacetylacetonate bis(ethylacetoacetate), titanium tributoxyacetylacetonate, titanium dibutoxybis(acetylacetonate), titanium tributoxyethylacetoacetate, titanium butoxyacetylacetonate bis (ethylacetoacetate), titanium tetrakis (acetylacetonate), titanium diacetylacetonate bis(ethylacetoacetate), bis(2-ethylhexanoate) titanium oxide, bis(laurate) titanium oxide, bis(naphthenate) titanium oxide , bis(stearate) titanium oxide, bis(oleate) titanium oxide, bis(linoleate) titanium oxide, tetrakis(2-ethylhexanoate) titanium, tetrakis(laurate) titanium, tetrakis(naphthenate) titanium, tetrakis(stearate) ) titanium, tetrakis (oleate) titanium, tetrakis (linoleate) titanium, tetrakis (2-ethyl-1,3-hexanediolate) titanium, and other compounds containing titanium.

Also, for example, tris(2-ethylhexanoate) bismuth, tris(laurate) bismuth, tris(naphthenate) bismuth, tris(stearate) bismuth, tris(oleate) bismuth, tris(linoleate) bismuth, tetraethoxyzirconium, Tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetra-sec-butoxyzirconium, tetra-tert-butoxyzirconium, tetra(2-ethylhexyl)zirconium, zirconium tributoxystearate, zirconium tributoxy Acetylacetonate, zirconium dibutoxy bis(acetylacetonate), zirconium tributoxyethylacetoacetate, zirconium butoxyacetylacetonate bis(ethylacetoacetate), zirconium tetrakis(acetylacetonate), zirconium diacetylacetonate bis(ethylacetoacetate) ), bis(2-ethylhexanoate) zirconium oxide, bis(laurate) zirconium oxide, bis(naphthenate) zirconium oxide, bis(stearate) zirconium oxide, bis(oleate) zirconium oxide, bis(linoleate) zirconium oxide, Compounds containing bismuth or zirconium such as tetrakis (2-ethylhexanoate) zirconium, tetrakis (laurate) zirconium, tetrakis (naphthenate) zirconium, tetrakis (stearate) zirconium, tetrakis (oleate) zirconium, tetrakis (linoleate) zirconium, etc. can be mentioned.

Further, for example, triethoxyaluminum, tri-n-propoxyaluminum, triisopropoxyaluminum, tri-n-butoxyaluminum, tri-sec-butoxyaluminum, tri-tert-butoxyaluminum, tri(2-1 ethylhexyl)aluminum, Aluminum dibutoxy stearate, aluminum dibutoxy acetylacetonate, aluminum butoxy bis(acetylacetonate), aluminum dibutoxyethyl acetoacetate, aluminum tris(acetylacetonate), aluminum tris(ethyl acetoacetate), tris(2-ethyl) Compounds containing aluminum such as aluminum hexanoate, aluminum tris(laurate), aluminum tris(naphthenate), aluminum aluminum stearate, aluminum aluminum tris(oleate), and aluminum aluminum tris(linoleate) can be mentioned.

Among the above-mentioned condensation promoters, titanium compounds are preferred, and titanium metal alkoxides, titanium metal carboxylates, and titanium metal acetylacetonate complex salts are particularly preferred.
The amount of the condensation accelerator to be used is preferably 0.1 to 10, with the number of moles of the compound being 0.1 to 10 relative to the total amount of hydrocarbyloxy groups present in the reaction system. Particularly preferred. By controlling the amount of the condensation promoter used within the above range, the condensation reaction proceeds efficiently.
The condensation reaction time is usually about 5 minutes to 10 hours, preferably about 15 minutes to 5 hours. By setting the condensation reaction time within the above range, the condensation reaction can be smoothly completed.
Further, the pressure of the reaction system during the condensation reaction is usually 0.01 to 20 MPa, preferably 0.05 to 10 MPa.

In addition, from the viewpoint of improving the low heat generation property and high temperature softening resistance of the vulcanized rubber, the content of modified rubber in the rubber component of the rubber composition is preferably 10 to 90% by mass, and 20% by mass. More preferably, it is 80% by mass.

(Carbon black)
The rubber constituting the side reinforcing rubber 9 and/or the bead filler 7 further contains carbon black in addition to the above-mentioned rubber components.
The carbon black has a nitrogen adsorption specific surface area of 5 to 40 m ² /g and a dibutyl phthalate oil absorption (DBP oil absorption) of 100 to 180 mL/100 g. By containing carbon black that satisfies this condition, the side reinforcing rubber 9 and/or the bead filler 7 can realize excellent durability while improving rolling resistance.
Specifically, the nitrogen adsorption method specific surface area of the carbon black is 5 to 40 m ² /g, which provides an excellent balance between the reinforcing properties of the side reinforcing rubber and low heat build-up. From the same viewpoint, the nitrogen adsorption specific surface area of the carbon black is preferably 15 to 35 m ² /g, more preferably 17 to 32 m ² /g.
Further, the DBP oil absorption amount of the carbon black is used as an index representing the degree of development of the aggregate structure of carbon black, and the larger the DBP oil absorption amount, the larger the aggregates tend to be. When the DBP oil absorption amount of the carbon black is 100 to 180 ml/100 g, an excellent balance between reinforcing properties of the side reinforcing rubber and low heat build-up is achieved. From the same viewpoint, the DBP oil absorption amount of the carbon black is preferably 105 to 160 ml/100 g, more preferably 108 to 145 ml/100 g.

In addition, from the viewpoint of achieving both rolling resistance and durability at a higher level, the compressed dibutyl phthalate oil absorption amount of the carbon black is preferably 36 to 110 mL/100 g, and preferably 50 to 95 mL/100 g. More preferably, it is 65 to 90 ml/100 g.
The compressed dibutyl phthalate oil absorption is a value obtained by measuring the DBP oil absorption after repeatedly applying pressure at 24,000 psi four times in accordance with ISO 6894. This compressed dibutyl phthalate oil absorption amount eliminates the DBP oil absorption amount due to the deformable and destructive structural form (secondary structure) caused by the so-called van der Waals force, and eliminates the DBP oil absorption amount due to the structural form of the non-destructive true structure (primary structure). This is an index for evaluating the skeletal structure specification of carbon black, which is mainly composed of a primary structure, and is used when determining the DBP oil absorption based on the structure.

In addition, the content of the carbon black is 40 to 40 to 100 parts by mass of the rubber component, from the viewpoint of the balance between rolling resistance and durability in the side reinforcing rubber 9 and/or the bead filler 7. The amount is preferably 100 parts by weight, more preferably 35 to 80 parts by weight, and even more preferably 40 to 69 parts by weight.

(Fillers other than carbon black)
The rubber composition used for the rubber constituting the side reinforcing rubber 9 and/or the bead filler 7 may further contain a filler other than the carbon black (hereinafter sometimes referred to as "other filler"). I can do it.
Examples of the other fillers include metal oxides such as alumina, titania, and silica, and reinforcing fillers such as clay and calcium carbonate, with silica being preferably used. Even if the air inside the tire is released and the side reinforcement rubber, bead filler, etc. are bent and the vulcanized rubber that makes up these parts generates heat, we use fillers with low heat generation to suppress the heat generation of the vulcanized rubber. It is preferable to use

Here, the type of silica is not particularly limited, but includes wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), colloidal silica, and the like. Silica may be a commercially available product, such as NIPSIL AQ (product name) from Tosoh Silica Corporation, Zeosil 1115MP (product name) from Rhodia, and VN-3 (product name) from Evonik Degussa. I can do it.
In addition, when using silica as a filler, in addition to strengthening the bond between the silica and rubber components and increasing reinforcing properties, the rubber composition is further , may contain a silane coupling agent.

In addition, the content (total total amount) of the filler in the rubber composition is 30 to 100 parts by mass per 100 parts by mass of the rubber component, from the viewpoint of further improving rolling resistance and durability. parts, preferably 30 to 100 parts by weight, more preferably 35 to 80 parts by weight, and even more preferably 40 to 70 parts by weight.

(vulcanizing agent, vulcanization accelerator)
The rubber composition (hereinafter sometimes simply referred to as "rubber composition") constituting the side reinforcing rubber 9 and/or the bead filler 7 may further include a vulcanizing agent and a vulcanization accelerator. .
The vulcanizing agent is not particularly limited, and sulfur is usually used, and examples thereof include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur.

Regarding the vulcanization accelerator, it is considered effective to include it from the viewpoint of further improving the rolling resistance and durability of the tire.

Further, from the viewpoint of further improving the rolling resistance and durability of the tire, the content (a) of the thiuram-based vulcanization accelerator in the rubber composition is 1.0 to 8 parts by mass based on 100 parts by mass of the rubber component. Preferably, it is .0 part by mass.
When the content (a) in the thiuram-based vulcanization-promoting rubber composition is 1.0 parts by mass or more based on 100 parts by mass of the rubber component, sufficient durability can be obtained, and the content (a) ) is 8.0 parts by mass or less, rubber burn is less likely to occur and a decrease in mechanical strength of the vulcanized rubber can be suppressed.

The thiuram-based vulcanization accelerator is not particularly limited and can be appropriately selected depending on the required performance of the vulcanized rubber. Examples of the thiuram-based vulcanization accelerator include tetrabenzylthiuram disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide, and the like.
However, if the composition is such that the total content of the vulcanization accelerator is less than the total content of the vulcanizing agents, the ratio of monosulfide bonds and disulfide bonds may be increased to From the viewpoint of improving the mechanical strength while increasing the softening resistance in .

The vulcanization accelerator preferably contains a sulfenamide vulcanization accelerator in addition to the above-mentioned thiuram vulcanization accelerator. By including a sulfenamide vulcanization accelerator in the vulcanization accelerator, the durability of the tire can be further improved.

More specifically, the content of the sulfenamide vulcanization accelerator in the rubber composition is preferably 0.80 to 4.50 parts by mass based on 100 parts by mass of the rubber component. The content of the sulfenamide vulcanization accelerator is more preferably 1.00 to 4.00 parts by mass based on 100 parts by mass of the rubber component from the viewpoint of further improving rolling resistance and durability.

Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide, N,N-dicyclohexyl-2-benzothiazolylsulfenamide, and N-tert-butyl-2- Benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2-benzothiazolylsulfenamide, N-propyl -2-Benzothiazolylsulfenamide, N-butyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-hexyl-2-benzothiazolylsulfenamide, N -heptyl-2-benzothiazolylsulfenamide, N-octyl-2-benzothiazolylsulfenamide, N-2-ethylhexyl-2-benzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide Phenamide, N-dodecyl-2-benzothiazolylsulfenamide, N-stearyl-2-benzothiazolylsulfenamide, N,N-dimethyl-2-benzothiazolylsulfenamide, N,N-diethyl- 2-Benzothiazolylsulfenamide, N,N-dipropyl-2-benzothiazolylsulfenamide, N,N-dibutyl-2-benzothiazolylsulfenamide, N,N-dipentyl-2-benzothiazoli Rusulfenamide, N,N-dihexyl-2-benzothiazolylsulfenamide, N,N-diheptyl-2-benzothiazolylsulfenamide, N,N-dioctyl-2-benzothiazolylsulfenamide, N , N-di-2-ethylhexylbenzothiazolylsulfenamide, N,N-didecyl-2-benzothiazolylsulfenamide, N,N-didodecyl-2-benzothiazolylsulfenamide, N,N-didecyl-2-benzothiazolylsulfenamide, Examples include stearyl-2-benzothiazolylsulfenamide. These sulfenamide vulcanization accelerators may be used alone or in combination of two or more.
Furthermore, among the above-mentioned sulfenamide-based vulcanization accelerators, N-cyclohexyl-2- Preferably, it contains at least one of benzothiazolylsulfenamide and N-tert-butyl-2-benzothiazolylsulfenamide.

In addition to the thiuram-based vulcanization accelerator and the sulfenamide-based vulcanization accelerator, the vulcanization accelerators include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithio-based vulcanization accelerators. It is also possible to further contain a vulcanization accelerator such as a carbamate type or xanthate type.
However, in a component composition in which the total content of the vulcanization accelerator is lower than the total content of the vulcanizing agent, the proportion of monosulfide bonds and disulfide bonds is increased, and the vulcanized rubber is From the viewpoint of improving mechanical strength while increasing softening resistance, it is preferable that the vulcanization accelerator comprises a thiuram-based vulcanization accelerator and a sulfenamide-based vulcanization accelerator.

(Other ingredients)
The rubber composition may contain various chemicals normally used in the rubber industry and compounding agents used in ordinary rubber compositions, as required, to the extent that the effects of the present invention are not impaired. can be done. For example, peroxides, vulcanization accelerators, vulcanization retarders, softeners such as various process oils, zinc white, stearic acid, waxes, anti-aging agents, compatibilizers, workability improvers, lubricants, adhesives. Examples include various commonly used compounding agents such as imparting agents, petroleum resins, ultraviolet absorbers, dispersants, and homogenizing agents.

By including the vulcanization retarder in the rubber composition, it is possible to suppress rubber burning caused by overheating of the rubber composition during preparation of the rubber composition. Moreover, the scorch stability of the rubber composition can be improved, and the extrusion of the rubber composition from a kneader can be facilitated.
The rubber composition preferably has a Mooney viscosity (ML ₁₊₄ , 130° C.) of 40 to 100, more preferably 50 to 90, and even more preferably 60 to 85. When the Mooney viscosity is within the above range, sufficient physical properties of the vulcanized rubber, including fracture resistance, can be obtained without impairing manufacturing processability.
Examples of the vulcanization retarder include phthalic anhydride, benzoic acid, salicylic acid, N-nitrosodiphenylamine, N-(cyclohexylthio)-phthalimide (CTP), sulfonamide derivatives, diphenylurea, and bis(tridecyl)pentaerythritol. Examples include diphosphites. As the vulcanization retarder, a commercially available product may be used, and examples thereof include "Santogard PVI" (trade name) [N-(cyclohexylthio)-phthalimide] manufactured by Monsanto Company. Among the above, N-(cyclohexylthio)-phthalimide (CTP) is preferably used as the vulcanization retarder.
When using the vulcanization retarder, the content of the vulcanization retarder in the rubber composition is as follows: The amount is preferably 0.1 to 1.0 parts by weight per 100 parts by weight of the rubber component.

Examples of the softener include process oil, thermoplastic resin, and the like.
Examples of the process oil include mineral oil derived from minerals, aromatic oil derived from petroleum, paraffin oil, naphthenic oil, palm oil derived from natural products, and the like.
Examples of thermoplastic resins include resins that soften or become liquid at high temperatures and make vulcanized rubber flexible, such as C5-based resins (including cyclopentadiene-based resins and dicyclopentadiene-based resins). ), various petroleum resins such as C9 type, C5/C9 mixed type, terpene type resin, terpene-aromatic compound type resin, rosin type resin, phenolic resin, alkylphenol resin, etc. Tackifier (does not contain curing agent) etc.

As the anti-aging agent, known anti-aging agents can be used, and examples thereof include, but are not particularly limited to, phenolic anti-aging agents, imidazole anti-aging agents, amine anti-aging agents and the like. The blending amount of these anti-aging agents is usually 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the rubber component.

In this way, the rubber composition can be obtained by kneading the components described above. The kneading method may be according to a method commonly practiced by those skilled in the art. For kneading, a kneading machine such as a roll, an internal mixer, or a Banbury rotor can be used. Furthermore, when molding into a sheet shape, band shape, etc., a known molding machine such as an extrusion molding machine or a press machine may be used.
For example, after kneading all components other than sulfur, a vulcanization accelerator (and a vulcanization retarder if necessary), and zinc oxide at 100 to 200°C, sulfur, a vulcanization accelerator, and zinc oxide ( If necessary, a vulcanization retarder) may be further added and kneaded at 60 to 130°C using a kneading roll machine or the like.

In addition, regarding the pneumatic tire of the present invention, the conditions other than the above-mentioned organic fiber cord, and at least one of the side reinforcing rubber and the bead filler are not particularly limited, and the tire can be manufactured according to a conventional method. For example, a rubber composition containing various chemicals is processed into various parts at an unvulcanized stage, and is pasted and molded on a tire molding machine by a conventional method to mold a green tire. This raw tire is heated and pressurized in a vulcanizer to obtain a pneumatic tire.
Further, as the gas to fill the tire, in addition to normal air or air with adjusted oxygen partial pressure, inert gas such as nitrogen, argon, helium, etc. can be used.

Furthermore, the pneumatic tire of the present invention can also be used as a run-flat tire because the side reinforcing rubber 9 and the bead filler 7 have excellent durability.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the Examples below.
Note that the samples of each example and comparative example of the present invention are predicted and calculated from data measured in the past.

(Production Example 1) Primary amine-modified polybutadiene rubber 1.4 kg of cyclohexane, 250 g of 1,3-butadiene, and 2,2-ditetrahydrofurylpropane (0.285 mmol) were injected as a cyclohexane solution into a 5L autoclave purged with nitrogen under nitrogen. After adding 2.85 mmol of n-butyllithium (BuLi) to this, polymerization was carried out for 4.5 hours in a 50° C. hot water bath equipped with a stirring device. The reaction conversion rate of 1,3-butadiene is approximately 100%. A part of this polymer solution was extracted into a methanol solution containing 1.3 g of 2,6-di-tert-butyl-p-cresol to stop the polymerization, and the solvent was removed by steam stripping. to obtain unmodified polybutadiene. As a result of measuring the microstructure (amount of vinyl bonds) of the obtained polybutadiene before modification, the amount of vinyl bonds was 30% by mass.
The polymer solution obtained as described above was maintained at a temperature of 50° C. without deactivating the polymerization catalyst, and the polymer solution was treated with N,N-bis(trimethylsilyl)amino in which the primary amino group was protected. 1129 mg (3.364 mmol) of propylmethyldiethoxysilane is added and a modification reaction is carried out for 15 minutes.
Thereafter, 8.11 g of tetrakis(2-ethyl-1,3-hexanediolate) titanium, which is a condensation accelerator, is added, and the mixture is further stirred for 15 minutes.
Finally, 242 mg of silicon tetrachloride was added as a metal halide compound, and 2,6-di-tert-butyl-p-cresol was added to the polymer solution after the reaction. Next, the solvent is removed and the protected primary amino group is deprotected by steam stripping, and the rubber is dried using a dry roll whose temperature is controlled at 110° C. to obtain a primary amine-modified polybutadiene rubber P.
As a result of measuring the microstructure (amount of vinyl bonds) of the obtained modified polybutadiene, the amount of vinyl bonds was 30% by mass.

(Production Example 2) Adhesive compositions 1 to 4
First, phloroglucinol was dissolved in water at 100°C to obtain a phloroglucinol-containing solution with a concentration of 10 wt%.
Thereafter, 18.2 g of 4% sodium hydroxide was added to 33.5 g of a 10 wt% phloroglucinol solution while stirring at a high temperature, and then diluted with 206 g of water, and 7.5 g of 25% aqueous ammonia was added. added. 6.4 g of 1,4-benzenedicarbaldehyde was gradually added to the above solution to obtain a phloroglucinol/1,4-benzenedicarbaldehyde-containing solution, which was then aged at the temperature and time shown in Table 3. A phenol/aldehyde resin was obtained.
Vinylpyridine-styrene-butadiene copolymer rubber (Vp) was added to the phenol/aldehyde resin obtained by aging the phloroglucinol/1,4-benzenedicarbaldehyde-containing solution, and the rubber was aged at 27°C for 24 hours. I did it. Furthermore, a specific isocyanate compound was added to the mixed solution of the phenol/aldehyde resin and Vp so as to have the compounding ratio shown in Table 2.
The ingredients of Adhesive Compositions 1 to 4 are shown in Tables 1 and 2 as Formulation A. In addition, Table 1 shows the blending amount (mass %) as a solid component, and Table 2 shows the blending amount (mass %) in a solution state.

*1: Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., used as a 10% aqueous solution *2: Manufactured by Tokyo Chemical Industry Co., Ltd., purity 98%
*3: Manufactured by Kanto Kagaku Co., Ltd., 1N NaOH aqueous solution *4: Manufactured by Kanto Kagaku Co., Ltd., 25% ammonia aqueous solution *5: Manufactured by Sime Darby, HYTEX HA
*6: Manufactured by JSR Corporation, SBR Latex 2108
*7: Manufactured by Japan A&L Co., Ltd., PYRATEX
*8: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., BN77, diluted to a solid content concentration of 18%.

<Adhesiveness evaluation>
A tire polyester cord coated with the adhesive composition of each sample was embedded in an unvulcanized rubber composition containing natural rubber, a rubber component consisting of a styrene-butadiene copolymer, carbon black, and a crosslinking agent. A test piece was vulcanized at 160° C. for 20 minutes under a pressure of 20 kgf/cm ² .
The obtained vulcanizate was cooled to room temperature, a cord was dug out from the vulcanizate, and the resistance (N/cord) when peeling the cord from the vulcanizate at a speed of 30 cm/min was determined at room temperature of 25 ± 1 °C. Measured at ambient temperature. Note that the drag force at this time was used as an index for evaluating adhesiveness.
Table 3 shows the resistance force during peeling of the test piece when using adhesive compositions 1 to 4 obtained by measurement.

[Examples 1-2, Comparative Example 1]
Each component is kneaded according to the composition shown in Table 4 to prepare a rubber composition.
Further, the obtained rubber composition is applied to the side reinforcing rubber 8 and the bead filler 7 shown in FIG. 1, and radial run flat tires for passenger cars each having a tire size of 205/65 R16 are manufactured according to a conventional method. The maximum thickness of the side reinforcing rubber of each trial tire was 12.0 mm, and the shape of the side reinforcing rubber was the same for each tire. Further, for the plies of the carcass 4 and the belt reinforcing layer 51, organic fiber cords whose surfaces were coated with the adhesive composition 4 shown in Table 3 were used.

<Measurement of physical properties and performance evaluation of vulcanized rubber>
(1) Low heat build-up evaluation The loss tangent (tan δ) was measured using a viscoelasticity measuring device (manufactured by Rheometrics Co., Ltd.) for vulcanized rubber test pieces cut from the side reinforcement rubber of the prototype tires produced in each Example and Comparative Example. Measurement is performed using a temperature of 50° C., a strain of 3%, and a frequency of 15 Hz.
The measured values are expressed as an index, with the reciprocal of tan δ of Comparative Example 1 being 100, and are shown in Table 4. The larger the index value, the better the tire with side reinforcement rubber has low heat build-up and rolling resistance.

(2) Durability Using the prototype tires produced in each Example and Comparative Example, the tires were run on a drum (at a speed of 80 km/h) without internal pressure, and the distance traveled on the drum until the tire became unable to run was measured. Flat mileage.
In Table 4, the run-flat mileage is expressed as an index with the run-flat mileage of the prototype tire of Comparative Example 1 as 100. The larger the index value, the more excellent the durability of the prototype tire.

The details of each component other than the modified polybutadiene rubber (primary amine modified polybutadiene rubber) in Table 4 are as follows. The content of each component is the amount (parts by mass) based on 100 parts by mass of the rubber component.
Natural rubber: RSS#1
Carbon black (Asahi #65): “Asahi #65” manufactured by Asahi Carbon [Nitrogen adsorption method specific surface area = 42 m ² /g, DBP oil absorption = 120 ml/100 g, compressed dibutyl phthalate oil absorption = 85 ml/100 g, Dst = 164 nm , ΔD50=134nm]
Carbon black (Asahi #52): "Asahi #52" manufactured by Asahi Carbon Co., Ltd. [Nitrogen adsorption method specific surface area = 28 m ² / g, DBP oil absorption = 128 ml / 100 g, compressed dibutyl phthalate oil absorption = 80 ml / 100 g, Dst = 231 nm , ΔD50=207nm]
Carbon black (Orion S204): “ECORAX S204” manufactured by Orion Engineered Carbons [Nitrogen adsorption method specific surface area = 19 m ² /g, DBP oil absorption = 138 ml/100 g, compressed dibutyl phthalate oil absorption = 76 ml/100 g, Dst = 246 nm, ΔD 50 =466nm]
DCPD resin: dicyclopentadiene petroleum resin, “Quinton 1105” manufactured by Nippon Zeon Co., Ltd.
Stearic acid: "Stearic acid 50S" manufactured by Shin Nippon Rika Co., Ltd.
Zinc white: “No. 3 zinc white” manufactured by Hakusui Tech Co., Ltd.
Antiaging agent (6C): N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide, “Noxela CZ-G” manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator TOT: Tetrakis (2-ethylhexyl) thiuram disulfide, “Noxeler TOT-N” manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Sulfur: Manufactured by Tsurumi Chemical Industry Co., Ltd., product name "Powdered Sulfur"

Table 4 shows that the prototype tire of Comparative Example 1, which does not meet the characteristics of carbon black, has poor low heat generation properties even if it has excellent durability, and is unable to achieve both low heat generation properties and durability. On the other hand, it can be seen that the trial tires of Examples 1 and 2 can extend the run-flat mileage without impairing low heat generation properties, and are also excellent in durability.

According to the present invention, it is an object of the present invention to provide a pneumatic tire in which an adhesive composition coated on an organic fiber cord does not contain resorcinol, has a low load on the environment, and has excellent rolling resistance. I can do it.

1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass 5 Belt 6 Bead core 7 Bead filler 8 Inner liner 9 Side reinforcement rubber 11 Tread rubber 50 Belt layer 51 Belt reinforcement layer

Claims (10)

A carcass consisting of one or more carcass plies extending from a pair of bead portions to a tread portion via a sidewall portion, and a pair of side reinforcements having a crescent-shaped cross section arranged on the inner side of the carcass in the tire width direction in the sidewall portion. A pneumatic tire comprising: rubber; and a bead filler disposed outside the bead core of the sidewall portion in the tire radial direction,
The pneumatic tire has an organic fiber cord coated with an adhesive composition containing polyphenols, aldehydes , and an isocyanate compound,
At least one of the side reinforcing rubber and the bead filler contains a rubber component and carbon black, and the carbon black has a nitrogen adsorption specific surface area of 5 to 40 m ² /g and an oil absorption amount of dibutyl phthalate. 100-180mL/100g ,
A pneumatic tire , wherein the polyphenols have three or more hydroxyl groups . The pneumatic tire according to claim 1, wherein the compressed dibutyl phthalate oil absorption amount of the carbon black is 36 to 110 mL/100 g. At least one of the side reinforcing rubber and the bead filler further includes a vulcanization agent and a vulcanization accelerator, and the vulcanization accelerator contains a thiuram vulcanization accelerator. The pneumatic tire according to claim 1 or 2. The pneumatic tire according to claim 3, wherein the vulcanization accelerator further contains a sulfenamide vulcanization accelerator. The pneumatic tire according to any one of claims 1 to 4, wherein the adhesive composition further contains rubber latex. The pneumatic tire according to any one of claims 1 to 5 , wherein the aldehyde has two or more aldehyde groups. The pneumatic tire according to any one of claims 1 to 6 , wherein the isocyanate compound is an aromatic compound containing a (blocked) isocyanate group. The pneumatic tire according to any one of claims 1 to 7 , wherein the organic fiber cord is used for a carcass ply and/or a belt reinforcing layer. The pneumatic tire according to any one of claims 1 to 8 , wherein the organic fiber cord is a hybrid cord made by twisting filaments made of two types of organic fibers. The pneumatic tire according to claim 9 , wherein the two types of organic fibers constituting the hybrid cord are selected from the group consisting of rayon, lyocell, polyester, nylon, and polykentone.

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