WO2021182544A1

WO2021182544A1 - Pneumatic tire

Info

Publication number: WO2021182544A1
Application number: PCT/JP2021/009656
Authority: WO
Inventors: 山本　雅彦
Original assignee: 株式会社ブリヂストン
Priority date: 2020-03-11
Filing date: 2021-03-10
Publication date: 2021-09-16
Also published as: JP7372857B2; JP2021142851A

Abstract

This pneumatic tire comprises a belt that has at least five belt layers, at least one of the belt layers being a spiral belt layer in which a rubberized layer of belt cord is wound so as to spiral in the tire circumferential direction, at least one of the belt layers being a slanted belt layer in which belt cord extends at a slant relative to the tire circumferential direction, and the belt cord of the belt layers being organic fiber cord that is coated with an adhesive composition that includes a polyphenol and an aldehyde.

Description

Pneumatic tires

The present invention relates to a pneumatic tire.

Organic fibers such as polyester fibers have a high initial elastic modulus and excellent thermal dimensional stability, and therefore, in the form of filaments, cords, cables, cord fabrics, canvas, etc., reinforce rubber articles such as tires. It is extremely useful as a material. Conventionally, various adhesive compositions have been proposed for improving the adhesiveness between a cord and rubber when these organic fibers are used as a tire cord. As an adhesive composition, for example, an RFL (resorcin formalin latex) adhesive containing resorcin, formalin, rubber latex and the like is used, and a technique for ensuring adhesive strength by heat-curing the RFL adhesive is known. (See, for example, Patent Documents 1 to 3 and the like). Regarding the adhesive composition, a technique using a resorcin formalin resin in which resorcin and formalin are initially condensed (see Patent Documents 4 and 5) and a tire cord made of polyester fiber or the like are pretreated with an epoxy resin. , A technique for improving adhesive strength is known.

Japanese Unexamined Patent Publication No. 58-2370 Japanese Unexamined Patent Publication No. 60-92371 Japanese Unexamined Patent Publication No. 60-96674 Japanese Unexamined Patent Publication No. 63-2497884 Special Publication No. 63-61433

However, in recent years, the amount of resorcin, which is generally used in the above-mentioned adhesive composition, has been required to be reduced in consideration of the working environment. Therefore, it is desired that the adhesive force between the cord and the rubber can be secured without using resorcin.

It is also desirable to improve the durability of tires in order to effectively use tire resources in consideration of the environment. Therefore, it is desirable that the adhesive strength can be ensured even if the working environment is improved without using resorcin, and as a result, the durability of the tire is also improved.

Therefore, the present invention provides a pneumatic tire in which resorcin is not contained in the adhesive composition coated on the organic fiber cord, the load on the environment is small, and the durability can be improved. With the goal.

The gist structure of the present invention is as follows.
Equipped with a belt consisting of five or more belt layers,
At least one of the belt layers is a spiral belt layer in which the rubberized layer of the belt cord is spirally wound in the tire circumferential direction.
At least one of the belt layers is an inclined belt layer in which the belt cord extends inclined with respect to the tire circumferential direction.
The belt cord of the belt layer is an organic fiber cord and is
The organic fiber cord is a pneumatic tire, characterized in that it is coated with an adhesive composition containing polyphenols and aldehydes.

According to the present invention, there is provided a pneumatic tire that does not contain resorcin in the adhesive composition coated on the organic fiber cord, has a low environmental load, and can improve durability. Can be done.

It is a tire width direction sectional view of the pneumatic tire which concerns on one Embodiment of this invention. It is a top view which shows the structure of the inclined belt layer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention in the tire width direction. In this embodiment, the pneumatic tire is an aircraft pneumatic radial tire and is configured to support the load of the aircraft.

As shown in FIG. 1, the tire 1 has five or more belt layers on the outer side in the tire radial direction of the crown portion of the carcass 3 straddling the pair of bead cores 2a embedded in the pair of bead portions 2 in a toroidal shape. A belt 4 composed of (six layers of belt layers 5a to 5f in the illustrated example) and a tread 5 arranged on the outer side of the belt 4 in the tire radial direction are provided.

As shown in FIG. 1, the tire of this example has a bead core 2a embedded in each pair of bead portions 2. In the illustrated example, the bead core 2a is composed of an annular cable bead. In the illustrated example, the bead core 2a has a circular cross section. As the bead wire, for example, a high carbon steel wire can be used.

Further, in this example, the bead filler 2b is arranged on the outer side of the bead core 2a in the tire radial direction. In the illustrated example, the bead filler 2b has a substantially triangular cross section in which the width in the tire width direction tapers from the inside to the outside in the tire radial direction, but the bead filler 2b has various cross-sectional shapes. Can be done. As the bead filler 2b, for example, one or more kinds of any known hard rubber can be used.

Further, as shown in FIG. 1, the tire of this example is provided with a carcass 3 (radial carcass) composed of two or more carcass plies. The number of carcass plies is not particularly limited as long as it is two or more, and may be, for example, three to eight or more. In this example, the carcass ply has 6 to 8 layers. The carcass 3 extends so as to straddle the pair of bead cores 2a in a toroidal manner. In the illustrated example, the carcass has a carcass main body extending so as to straddle the pair of bead cores 2a in a toroidal manner, and a carcass folded portion extending from the carcass main body and folded around the bead core 2a from the inside to the outside in the tire width direction. .. It should be noted that, as appropriate, one or more carcass plies may be made into a down ply consisting of only the carcass main body portion extending so as to straddle the pair of bead cores 2a in a toroidal manner. Although not shown, the tire radial positions of the ends of two or more carcass plies are preferably different from the viewpoint of suppressing the occurrence of failure due to the ends, and on the other hand, they can be the same. As the carcass cord, an organic fiber cord can be used, for example, a cord made of nylon fiber can be used, or a hybrid cord made by twisting two kinds of organic fiber cords can be used (for example, aramid). Hybrid cord of fiber and nylon fiber).

Belt 4 is composed of five or more belt layers. In the illustrated example, the belt 4 is composed of six belt layers 4a to 4f, and the

belt layers

4a, 4b, 4c, 4d, 4e, and 4f are laminated in this order from the inside in the tire radial direction.

Here, at least one of the belt layers is a spiral belt layer in which the rubberized layer of the belt cord is spirally wound in the tire circumferential direction. In the illustrated example, one layer of the belt layer 4a is a spiral belt layer.

FIG. 2 is a plan view showing the configuration of the inclined belt layer. At least one of the belt layers is an inclined belt in which the belt cord extends at an inclination with respect to the tire circumferential direction (for example, at an inclination angle of 2 to 40 °). More specifically, as shown in FIG. 2, in this example, at least one layer of the belt layer has a rubber-coated strip member 51 of the belt cord from one tire width direction end to the other tire width direction end. Extends toward, folds back at the other tire width end, extends from the other tire width end to one tire width end, folds back at one tire width end, and one This is an endless belt layer in a state of being spirally wound in the tire circumferential direction so that the tire extends from the tire width direction end to the other tire width direction end repeatedly. In the illustrated example, the five layers of the belt layers 4b to 4f are endless belt layers. The endless belt layer is also called an endless belt layer because there is no cut surface of the organic fiber cord at both ends in the tire width direction.

Here, the belt cords of the respective belt layers 4a to 4f are organic fiber cords, and the organic fiber cords are coated with an adhesive composition containing polyphenols and aldehydes. In this example, the organic fiber cord comprises at least aramid fibers. The organic fiber cord is a hybrid cord formed by twisting filaments made of two types of organic fibers. Specifically, in this example, the organic fiber cord is a hybrid cord formed by twisting an aramid fiber and a nylon fiber. The description of the organic fiber code such as the description of polyphenols and aldehydes will be described later, and the internal structure of other tires will be described first.

The belt structure is not limited to the example of the embodiment shown in FIG. 1, and is composed of five or more belt layers, in which at least one of the belt layers is the above-mentioned spiral belt layer, and of the belt layers. At least one layer is the above-mentioned inclined belt layer (for example, endless belt layer), the belt cord of the belt layer is an organic fiber cord, and the organic fiber cord is coated with an adhesive composition containing polyphenols and aldehydes. It is good if it is done. The width of the five or more belt layers in the tire width direction can be appropriately set, and the magnitude relationship of the widths between the belt layers is not particularly limited. Hereinafter, some modifications of the belt structure will be illustrated, but the present invention is not limited to these belt structures.

(I) For example, in the above example, the number of inclined belt layers (for example, endless belt layers) may be 6 to 9 layers. Alternatively, (ii), for example, in the above example, the carcass cord may be a hybrid cord formed by twisting aramid fibers and nylon fibers. Alternatively, (iii), for example, a spiral belt layer may be arranged inside and outside the inclined belt layer (for example, an endless belt layer) in the tire radial direction. As an example, a tire having two spiral belt layers. A configuration in which four inclined belt layers (for example, endless belt layers) are arranged on the radial outer side, and three spiral belt layers are arranged on the tire radial outer side of the inclined belt layer (for example, endless belt layer). can do. Alternatively, (iv), for example, a two-layer inclined belt layer (for example, an endless belt layer) using a belt cord made of aramid fiber is provided on the outer side in the tire radial direction of a six-layer spiral belt layer using a belt cord made of aramid fiber. Can be arranged. Alternatively, (v) for example, six inclined belt layers (for example, endless belt layers) may be arranged outside the one spiral belt layer in the tire radial direction, or (vi) for example, for example. The configuration may be such that four inclined belt layers (for example, endless belt layers) are arranged outside the tire radial direction of the two spiral belt layers, or (vii) the tire radial direction of the six spiral belt layers. It is also possible to have a configuration in which two inclined belt layers (for example, an endless belt layer) are arranged on the outside.
In any of the examples, the material and the number of carcass ply cords are not particularly limited.

Further, the tire 1 has an inner liner (not shown). The inner liner is arranged so as to cover the inner surface of the tire 1.

Next, the polyphenols and aldehydes of the adhesive composition used for the adhesive between the belt cord and the rubber will be described.

(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 enhanced. Here, the polyphenols are water-soluble polyphenols and are not limited as long as they are polyphenols other than resorcin (resorcinol), and the number of aromatic rings and the number of hydroxyl groups can be appropriately selected. .. Further, the polyphenols preferably have two or more hydroxyl groups, and more preferably three or more hydroxyl groups, from the viewpoint of realizing more excellent adhesiveness. Since the polyphenol or the condensate of the polyphenol is water-soluble in the adhesive composition liquid containing water by containing three or more hydroxyl groups, it can be uniformly distributed in the adhesive composition, so that more excellent adhesiveness can be realized. .. Further, when the polyphenols are polyphenols containing a plurality of (two or more) aromatic rings, two or three hydroxyl groups are present at the ortho, meta or para positions in those aromatic rings, respectively.

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

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

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

(Aldehydes)
The adhesive composition contains aldehydes as a resin component in addition to the above-mentioned polyphenols. By containing aldehydes in the adhesive composition, high adhesiveness can be realized together with the above-mentioned polyphenols. Here, the aldehydes are not particularly limited and can be appropriately selected depending on the required performance. Derivatives of rudehydrs originating from aldehydes are also included in the range of aldehydes. Examples of aldehydes include monoaldehydes such as formaldehyde, acetaldehyde, butylaldehyde, achlorine, propionaldehyde, chloral, butylaldehyde, caproaldehyde, and allylaldehyde, and glioxal, malonaldehyde, succinaldehyde, glutaaldehyde, and adipho. Examples thereof include aliphatic dialdehydes such as aldehydes, aldehydes having an aromatic ring, and dialdehyde starch. These aldehydes may be used alone or in combination of two or more. Among these, the aldehydes preferably contain aldehydes having an aromatic ring. This is because better adhesiveness can be obtained. The aldehydes preferably do not contain formaldehyde. 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% by mass.

Aldehydes having an aromatic ring are aromatic aldehydes containing at least one aromatic ring in one molecule and having at least one aldehyde group. Aldehydes having an aromatic ring can form a relatively inexpensive resin that has a low impact on the environment and has excellent mechanical strength, electrical insulation, acid resistance, water resistance, heat resistance, and the like. can. Further, the aldehydes having an aromatic ring preferably have two or more aldehyde groups from the viewpoint of realizing better adhesiveness. By cross-linking and condensing aldehydes with a plurality of aldehyde groups, the degree of cross-linking of the thermosetting resin can be increased, so that the adhesiveness can be further enhanced. Furthermore, when aldehydes have two or more aldehyde groups, it is more preferable that two or more aldehyde groups are present in one aromatic ring. Each aldehyde group can be present at the ortho, meta or para position in one aromatic ring. Examples of such aldehydes include 1,2-benzenedicarboxardhide, 1,3-benzenedicarboxardhide, 1,4-benzenedicarbaldehyde 1,4-benzenedicarbaldehyde, and 2-hydroxy. Benzene-1,3,5-tricarbaldehyde, a mixture of these compounds and the like can be mentioned.

Among these, from the viewpoint of achieving better adhesiveness, it is preferable to use at least 1,4-benzenedicarbaldehyde as the aldehydes having an aromatic ring.

Further, the aldehydes having an aromatic ring include not only those having a benzene ring but also heteroaromatic compounds. Examples of aldehydes that are heteroaromatic compounds include aldehydes having a furan ring as shown below.

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

Examples of the aldehydes having a furan ring include the following compounds.

(In the notation, R stands for -H or -CHO; R1, R2 and R3 represent alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl groups, respectively.)

In the adhesive composition, polyphenols and aldehydes are condensed, and the mass ratio of the polyphenols to the aldehydes having an aromatic ring (content of aldehydes having an aromatic ring / content of polyphenols). ) Is preferably 0.1 or more and 3 or less, and more preferably 0.25 or more and 2.5 or less. This is because a condensation reaction occurs between polyphenols and aldehydes having an aromatic ring, and the hardness and adhesiveness of the resin, which is the product of the condensation reaction, become more suitable.

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

(Isocyanate compound)
The adhesive composition preferably 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 adhesiveness of the adhesive composition. Here, the isocyanate compound is a compound having an action of promoting adhesion to a resin material (for example, a phenol / aldehyde resin obtained by condensing polyphenols and aldehydes) which is an adherend of an adhesive composition. It 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 a (blocked) isocyanate group-containing aromatic compound from the viewpoint of further improving the adhesiveness. When an isocyanate compound is contained in the adhesive composition, blocked) isocyanate group-containing aromatics are distributed at positions near the interface between the adherend fiber and the adhesive composition, and an effect of promoting adhesion can be obtained. By this action and effect, the adhesion with the organic cord can be further enhanced. The (blocked) isocyanate group-containing aromatic compound is an aromatic compound having a (blocked) isocyanate group. Further, "(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 reacting with a blocking agent for the isocyanate group and a block for the isocyanate group. It contains an isocyanate group that has not reacted with the agent, or an isocyanate group that is generated by dissociating a blocking agent of a blocked isocyanate group.

Further, the (blocked) isocyanate group-containing aromatic compound preferably contains a molecular structure in which aromatics are bonded by an alkylene chain, and more preferably contains a molecular structure in which aromatics are bonded to methylene. Examples of the molecular structure in which aromatics are bonded by an alkylene chain include a molecular structure found in diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate, or a condensate of phenols and formaldehyde. As the (blocked) isocyanate group-containing aromatic compound, for example, a compound containing an aromatic polyisocyanate and a heat-dissociable blocking agent, diphenylmethane diisocyanate or an aromatic polyisocyanate was blocked with a heat-dissociable blocking agent. Examples thereof include water-dispersible compounds containing components and aqueous urethane compounds. Preferable examples of the compound containing an aromatic polyisocyanate and a heat-dissociable blocking agent include a blocked isocyanate compound containing diphenylmethane diisocyanate and a known isocyanate blocking agent. As the water-dispersible compound containing a component obtained by blocking the above diphenylmethane diisocyanate or aromatic polyisocyanate with a thermal dissociable blocking agent, diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate is used as a known blocking agent for blocking isocyanate groups. Examples of the reaction product blocked in. Specifically, commercially available blocked products such as Elastron BN69 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Erastron BN77 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and Meicanate TP-10 (manufactured by Meisei Kagaku Kogyo Co., Ltd.) Polyisocyanate compounds can be used. The aqueous urethane compound includes an organic polyisocyanate compound (α) having a molecular structure in which aromatics are bonded by an alkylene chain, preferably a molecular structure in which aromatics are bonded to methylene, and a compound having a plurality of active hydrogens (β). ) And a thermally dissociable blocking agent (γ) for an isocyanate group. In addition, the aqueous urethane compound (F) not only acts as an adhesive improver due to its flexible molecular structure, but also acts as a flexible cross-linking agent to suppress the fluidization of the adhesive at high temperatures. Have. In addition, "water-based" indicates that it is water-soluble or water-dispersible, and "water-soluble" does not necessarily mean completely water-soluble, but is partially water-soluble or has an adhesive composition. It means a substance that does not undergo phase separation in an aqueous solution of the substance.

Here, as the aqueous urethane compound (F), for example, the following general formula (I):

(In the formula, A indicates a residue from which the active hydrogen of the organic polyisocyanate compound (α) containing a molecular structure in which aromatics are bonded by an alkylene chain is eliminated, and Y indicates a thermally dissociable block to the isocyanate group. The active hydrogen of the agent (γ) indicates the desorbed residue, Z indicates the residue of the compound (δ) desorbed, and X indicates the active hydrogen of the compound (β) having a plurality of active hydrogens. It is a desorbed residue, n is an integer of 2 to 4, and p + m is an integer of 2 to 4 (m ≧ 0.25)), and an aqueous urethane compound is preferable.

Examples of the organic polyisocyanate compound (α) containing a molecular structure in which aromatics are bonded by an alkylene chain include methylene diphenyl polyisocyanate and polymethylene polyphenyl polyisocyanate. The compound (β) having a plurality of active hydrogens is preferably a compound having 2 to 4 active hydrogens and having an average molecular weight of 5,000 or less. Examples of such compound (β) include (i) polyhydric alcohols having 2 to 4 hydroxyl groups, and (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 Polybutadiene polyols having hydroxyl groups and copolymers of them with other vinyl monomers, (vi) Polychloroprene polyols having 2 to 4 hydroxyl groups and copolymers of them with other vinyl monomers, (vii). Polyether polyols having 2 to 4 hydroxyl groups, which are C2-C4 alkylene oxide heavy additions of polyhydric amines, polyhydric phenols and amino alcohols, and C2-C4 of C3 and higher polyhydric alcohols. Examples thereof include alkylene oxide heavy adducts, alkylene oxide copolymers of C2 to C4, and alkylene oxide polymers of C3 to C4. Further, the heat dissociable blocking agent (γ) for the isocyanate group is a compound capable of liberating the isocyanate group by heat treatment, and examples thereof include known isocyanate blocking agents. Furthermore, compound (δ) is a compound having at least one active hydrogen and anionic and / or nonionic hydrophilic groups. Examples of the compound having at least one active hydrogen and an anionic hydrophilic group include aminosulfonic acids such as taurine, N-methyltaurine, N-butyltaurine and sulfanilic acid, and aminocarboxylic acids such as glycine and alanine. Be done. On the other hand, as a compound having at least one active hydrogen and a nonionic hydrophilic group, for example, compounds having a hydrophilic polyether chain can be mentioned.

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

(Rubber latex)
The adhesive composition can substantially further contain rubber latex in addition to the polyphenols, aldehydes and isocyanate compounds described above. 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), butyl halide rubber, acryloni little-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, the rubber latex is preferably mixed with phenols and aldehydes before blending the isocyanate compound. Further, 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 an organic fiber cord is not particularly limited, but for example, a method of mixing and aging raw materials such as the polyphenols, aldehydes, and rubber latex, or a method of mixing polyphenols and aldehydes. After aging by mixing with, a method of further adding rubber latex and aging can be mentioned. When an isocyanate compound is contained, the rubber latex can be added and aged, and then the isocyanate compound can be added. The composition and content of the polycyclic aromatic hydrocarbons, aldehydes, rubber latex and isocyanate compound are the same as those described in the above-mentioned adhesive composition.

(Rubber-organic fiber cord composite)
Here, the tire of the present invention has an organic fiber cord coated with an adhesive composition, and the organic fiber cord coated with the adhesive composition is adhered to a rubber member such as a coated rubber to be rubber. -Forms an organic fiber cord composite. Since the obtained rubber-organic fiber cord composite uses the above-mentioned adhesive composition, the burden on the environment is small. Here, in the tire of the present invention, the rubber-organic fiber cord composite can be used as, for example, the carcass ply 30 and the belt reinforcing layer 50.
Among these, the rubber-organic fiber cord composite is preferably used for at least one of the carcass and the belt reinforcing layer. This is because the organic fiber cord coated with the adhesive composition can reduce the load on the environment and more effectively exhibit the excellent adhesiveness between the organic fiber and the rubber member. In the rubber-organic fiber cord composite, the adhesive composition may cover at least a part of the organic fiber cord, but it is adhered from the viewpoint that the adhesiveness between the rubber and the organic fiber cord can be further improved. It is preferable that the agent composition is coated on the entire surface of the organic fiber cord. The material of the organic fiber cord is not particularly limited and can be appropriately selected depending on the intended use. For example, an aliphatic polyamide fiber cord such as polyester, 6-nylon, 6,6-nylon, 4,6-nylon, a polyketone fiber cord, and a synthetic resin represented by an aromatic polyamide fiber cord typified by paraphenylene terephthalamide. It can be used for textile materials. The organic fiber cord can be formed, for example, with a monofilament or a stranded wire.

The organic fiber cord is 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 steering stability and high-speed durability at a high level. preferable. Further, from the viewpoint of further improving high-speed durability, the hybrid cord preferably has a heat shrinkage stress (cN / dtex) at 177 ° C. of 0.20 cN / dtex or more, and is 0.25 to 0.40 cN / dtex. It is more preferable that it is within the range of. Furthermore, from the viewpoint of further improving the steering stability at low speed and high temperature, the hybrid cord has a tensile elastic modulus of 60 cN / dtex or less at 1% strain at 25 ° C., particularly 35 to 50 cN / dtex. It is preferable that the tensile elastic 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 rayon, lyocell and the like can be mentioned as highly rigid organic fibers, and polyester and the like can be mentioned as organic fibers having a high heat shrinkage rate. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), nylon, polyketone (PK) and the like can be mentioned. More preferably, a combination of rayon or lyocell and nylon can be used.
As a method of adjusting the heat shrinkage stress and tensile elastic modulus of the hybrid cord using these organic fibers, there is a method of controlling the tension at the time of the dip treatment. For example, the dip treatment is performed while applying a high tension. Therefore, the value of the heat shrinkage stress of the cord can be increased. That is, although each organic fiber has a unique range of physical characteristics, by controlling the dip treatment conditions, the physical properties can be adjusted within that range to obtain a hybrid cord having desired physical properties.
Alternatively, the organic fiber cord is preferably a single wire cord having no weft. By not having the weft, it is possible to suppress a decrease in fatigue resistance due to rubbing between the warp and the weft.

Hereinafter, the action and effect of the pneumatic tire of the present embodiment will be described.

The pneumatic tire of the present embodiment first has an organic fiber cord coated with an adhesive composition containing polyphenols and aldehydes (used for the belt cord in this example). As a result, the adhesive composition coated on the belt cord does not contain resorcin, the load on the environment is small, and high adhesiveness between the cord and the rubber can be achieved.
Further, in the pneumatic tire of the present embodiment, since the inclined belt layer is used for at least one of the five or more belt layers, the tag effect can be obtained. In particular, in the present embodiment, since the endless belt layer is used as the inclined belt layer, it is possible to suppress a failure caused by the end of the belt cord and improve the durability of the tire. Further, in the pneumatic tire of the present embodiment, since the spiral belt layer is used for at least one of the five or more belt layers, the diameter growth can be suppressed.

The number of spiral belt layers is preferably 1 to 7. By increasing the number of spiral belt layers to some extent (for example, two or more layers), diameter growth can be further suppressed, while from the viewpoint of weight reduction, the number of spiral belt layers is increased. The smaller the number (for example, one layer as in the present embodiment) is preferable. Here, it is preferable that the spiral belt layer is arranged in the innermost layer in the tire radial direction among the belt layers.

The number of inclined belt layers (for example, endless belt layers) is preferably 1 to 7. By increasing the number of inclined belt layers (for example, endless belt layer) to some extent (for example, 5 layers as in the present embodiment), durability can be further improved, while weight reduction is achieved. Therefore, it is preferable that the number of inclined belt layers (endless belt layers) is small (for example, one layer or two layers).

The tire of the present invention is preferably for an aircraft.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in each of the above examples, the combination of the belt structure and the carcass structure can be arbitrary. The tire of the present invention can be molded by steam vulcanization or electric vulcanization.

1: Tire,
2: Bead part,
3: Carcass,
4: Belt,
5: Tread

Claims

Equipped with a belt consisting of five or more belt layers,
At least one of the belt layers is a spiral belt layer in which the rubberized layer of the belt cord is spirally wound in the tire circumferential direction.
At least one of the belt layers is an inclined belt layer in which the belt cord extends inclined with respect to the tire circumferential direction.
The belt cord of the belt layer is an organic fiber cord and is
The organic fiber cord is a pneumatic tire, characterized in that it is coated with an adhesive composition containing polyphenols and aldehydes.
In the inclined belt layer, a strip member having a rubber coating of the belt cord extends from one tire width direction end toward the other tire width direction end and is folded back at the other tire width direction end to form the other. It may extend from the tire width direction end toward one tire width direction end, be folded back at one tire width direction end, and extend from one tire width direction end toward the other tire width direction end. The pneumatic tire according to claim 1, which is an endless belt layer in a state of being spirally wound in the tire circumferential direction so as to be repeated.
The pneumatic tire according to claim 1 or 2, wherein the organic fiber cord contains at least aramid fiber.
The pneumatic tire according to any one of claims 1 to 3, wherein the organic fiber cord is a hybrid cord formed by twisting filaments made of two types of organic fibers.
The pneumatic tire according to claim 4, wherein the organic fiber cord is a hybrid cord formed by twisting aramid fiber and nylon fiber.
The pneumatic tire according to any one of claims 1 to 5, wherein the polyphenols have three or more hydroxyl groups.
The pneumatic tire according to any one of claims 1 to 6, wherein the aldehydes have two or more aldehyde groups.
The pneumatic tire according to any one of claims 1 to 7, wherein the number of layers of the spiral belt layer is 1 to 7.
The pneumatic tire according to any one of claims 1 to 8, wherein the number of layers of the inclined belt layer is 1 to 7.
The pneumatic tire according to any one of claims 1 to 9, wherein the spiral belt layer is arranged in the innermost layer in the tire radial direction of the belt layer.
The pneumatic tire according to any one of claims 1 to 10, which is for an aircraft.