JP2018149989A - Tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for heavy load in which damage of a carcass ply formed of a metal cord-rubber composite is further prevented and which therefore allows for improvement in the durability as the whole tire.SOLUTION: A metal cord used for a metal cord-rubber composite forming a carcass ply 24 includes N atom of 2 atomic %-60 atomic % and has a Cu/Zn ratio of 1-4 in a surface thereof. A rubber composition covering the metal cord includes silica of 1-15 pts.mass and cobalt-containing compound of 0-1 pts.mass based on a rubber component of 100 pts.mass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heavy duty tire with improved durability.

  Conventionally, a heavy duty tire has a metal cord-rubber composite in which a metal cord is coated with a rubber composition, a belt for forming a belt layer, and a carcass ply for forming a carcass for the purpose of increasing strength and improving durability. Etc.

  In order for the metal cord-rubber composite to exhibit a high reinforcing effect, excellent adhesiveness that bonds the metal cord and the rubber composition stably and strongly is required. When the tire becomes hot due to heat generated by friction or the like during running or when used in a high temperature environment, if this excellent adhesion cannot be maintained, that is, if the heat resistant adhesion is low, the metal cord and the rubber composition are peeled off. Is likely to occur, leading to a decrease in the strength of the tire, which causes a decrease in durability.

  Moreover, in order for a metal cord-rubber composite to exhibit a high reinforcing effect, good crack resistance of the rubber composition is required. If the fatigue of the rubber composition increases due to the shear force caused by the tire pressure, as well as the dynamic shear force applied by the load, driving force, braking force and lateral force applied to the tire, Cracks are likely to occur. The occurrence of cracks leads to a decrease in tire strength and causes a decrease in durability.

  Therefore, a proposal has been made to improve adhesion and crack resistance in a metal cord-rubber composite (for example, Patent Document 1).

International Publication No. 2014/192811

  By using a metal cord-rubber composite using conventional techniques for improving adhesiveness and crack resistance, durability of heavy duty tires is being improved. However, in pulverization sites, mines, dam construction sites, etc., heavy-duty tires used in harsh environments where physical and thermal loads are further increased, such as steep uneven road surfaces and severe high temperature conditions. On the other hand, there is a demand for a longer life, and further improvement in durability as a heavy duty tire is desired. In heavy-duty tires, damage to the carcass ply due to physical and thermal loads has a significant effect on the durability of the entire tire, and further damage prevention of the carcass ply is desired.

  An object of the present invention is to provide a heavy duty tire capable of further preventing the damage of a carcass ply formed by a metal cord-rubber composite and further improving the durability of the entire tire. To do.

Therefore, the present invention provides the following heavy duty tires.
(1) having a tread portion, a pair of sidewall portions connected to both ends of the tread portion, a pair of bead portions in which a bead core is embedded and continuing to the sidewall portion, and a rewinding portion that rewinds around the bead core. A heavy duty tire comprising a carcass extending in a toroidal shape between a pair of the bead parts,
The carcass is formed by at least one carcass ply;
At least one carcass ply is formed of a metal cord-rubber composite formed by coating a rubber composition on each of a plurality of metal cords,
The metal cord has a surface N atom of 2 atomic% or more and 60 atomic% or less, and a Cu / Zn ratio of the surface of 1 or more and 4 or less, and the rubber composition is based on 100 parts by mass of a rubber component, A heavy-duty tire comprising 1 to 15 parts by mass of silica and 0 to 1 part by mass of a cobalt-containing compound.
(2) comprising a belt layer disposed between the carcass and the tread portion;
The belt layer is formed by a plurality of laminated belts,
The heavy duty tire according to (1), wherein the at least one belt is formed of the metal cord-rubber composite.
(3) A reinforcing band disposed on the side opposite to the bead core side of the winding portion in the carcass,
The reinforcing band is formed by at least one wire chafer,
The heavy duty tire according to (1) or (2), wherein at least one of the wire chafers is formed of the metal cord-rubber composite.
(4) The metal cord is a metal cord made of a single wire of a metal wire having brass plating applied to the peripheral surface or a plurality of twisted wires, and the brass plating composition is 40 to 80% by mass of Cu and Zn is made of The heavy-duty tire according to any one of (1) to (3), wherein the tire is 20 to 60% by mass.
(5) The metal cord is formed by surface treatment with a buffer solution having a pH of 5.0 to 7.2, 1,2,4-triazole, 1,2,3-triazole, 3-amino-1,2,4- And a treatment with one or more triazole compounds selected from triazole, 4-amino-1,2,4-triazole, benzotriazole, tolyltriazole, and 3-mercapto-1,2,4-triazole. The heavy duty tire according to any one of (1) to (4).
(6) The heavy duty tire according to any one of (1) to (5), wherein the rubber composition does not contain a cobalt-containing compound.

  In the carcass ply formed of the metal cord-rubber composite, the present invention realizes a higher degree of compatibility between the improvement in heat-resistant adhesion between the metal cord and the rubber composition and the improvement in crack resistance of the rubber composition. Thus, it is possible to provide a heavy load tire that can further prevent damage and further improve the durability of the entire tire.

FIG. 1 is a cross-sectional view in the tire width direction according to an embodiment. FIG. 2 is a partially enlarged cross-sectional view of the third belt shown in FIG.

  Hereinafter, a heavy duty tire according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  FIG. 1 shows a cross-sectional view in the tire width direction of a heavy duty tire according to an embodiment of the present invention. This figure is a sectional view in the tire width direction in a state in which the present embodiment is assembled to an applied rim and filled with a prescribed air pressure. FIG. 2 is a partially enlarged cross-sectional view of the third belt shown in FIG.

  Here, the applicable rim is a rim stipulated in an industrial standard effective for an area where tires are produced and used. For example, in Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO ( European Tire and Rim Technical Organization (STANDARD MANUAL) In the US, TRA (THE TIRE and RIM ASSOCIATION INC.) Refers to the rim defined in YEAR BOOK.

  In addition, “specified air pressure” refers to the air pressure specified in accordance with the maximum load capacity in the above standard, and “maximum load capacity” is permitted to be applied to the tire in accordance with the above standard. The maximum mass.

  As shown in FIG. 1, the heavy load tire 10 includes a tread portion 11, a pair of sidewall portions 12 that are continuous with both ends of the tread portion 11, and a pair of bead portions 13 that are continuous with the sidewall portion 12. ing. A bead core 15 is embedded in the bead portion 13. In FIG. 1, grooves and blocks provided on the tread surface 11 a that is the surface of the tread portion 11 are omitted. CL is the tire equator plane.

  Between the pair of bead portions 13, there is a carcass 14 composed of a single carcass ply 24 extending in a toroidal shape. The carcass 14 includes, for example, a rewinding portion 14b (a rewinding portion 24b of the carcass ply 24) that rewinds around the bead core 15 embedded in the bead portion 13 from the inner side to the outer side in the tire width direction. It is locked to the bead core 15 by 14b. On the contrary, it is also possible to lock by rolling back from the outer side in the tire width direction toward the inner side. The carcass 14 may be formed by laminating a plurality of carcass plies 24 from, for example, the tire inner periphery side to the outer periphery side.

  A reinforcing band 17 composed of a single wire chafer 27 is disposed on the side opposite to the bead core 15 side of the winding portion 14 b of the carcass 14. The reinforcing band 17 is provided adjacent to the winding-back portion 14b and along the winding-back portion 14b, and suppresses deformation of the bead portion 13. The reinforcing band 17 may be formed by laminating a plurality of wire chafers 27, for example, from the tire inner peripheral side to the outer peripheral side.

  A belt layer 16 formed by laminating six belts 16a to 16f in the tire radial direction is disposed between the carcass 14 and the tread portion 11, that is, on the outer side in the tire radial direction of the crown portion 14a of the carcass 14. ing. The six belts are referred to as a first belt 16a, a second belt 16b, a third belt 16c, a fourth belt 16d, a fifth belt 16e, and a sixth belt 16f in order from the inner side (inner circumferential side) in the tire radial direction. The belt layer may be any layer in which two or more belts are laminated.

  The first belt 16a and the second belt 16b mainly serve to maintain the internal pressure and maintain the tire shape, and the fifth belt 16e and the sixth belt 16f mainly serve to block the external pressure. The third belt 16c and the fourth belt 16d play a large role in improving the wear resistance of the surface of the tread portion 11. The belt layer 16 as a whole functions to increase the rigidity of the tread portion 11.

  The carcass ply 24, the wire chafer 27, and the belts 16a to 16f are each formed of a metal cord-rubber composite formed by coating a rubber composition on each of a plurality of metal cords. As a representative, a partial enlarged cross-sectional view of the third belt 16c is shown in FIG. As shown in FIG. 2, the third belt 16 c is formed of a metal cord-rubber composite 163 in which a plurality of metal cords 161 are each coated with a rubber composition 162. The other belts 16a to 16f, the carcass ply 24, and the wire chafer 27 have substantially the same configuration.

  In the present embodiment, a new metal cord-rubber composite is used for the carcass ply 24. This is because in the heavy duty tire, the carcass ply 24 has a greater contribution to the durability improvement of the entire tire than the belts 16a to 16f and the wire chafer 27, and the metal cord and the rubber composition in the carcass ply 24 are This is because the prevention of damage by a high degree of compatibility between the improvement in heat-resistant adhesion of the rubber and the improvement in crack resistance of the rubber composition greatly affects the durability improving effect on the entire tire.

  The metal cord in this new metal cord-rubber composite has a surface N (nitrogen) atom of 2 to 60 atom% and a surface Cu / Zn ratio of 1 to 4 and covers the metal cord. The rubber composition to be used contains 1 to 15 parts by mass of silica and 0 to 1 part by mass of a cobalt-containing compound with respect to 100 parts by mass of the rubber component. The metal cord-rubber composite having this configuration is excellent in both heat resistance adhesion and crack growth resistance (crack resistance) between the metal cord and the rubber composition, and improved in heat resistance adhesion between the metal cord and the rubber composition. The improvement of crack growth resistance (crack resistance) can be achieved at a high level. This mechanism will be described later.

In this embodiment, by using this new metal cord-rubber composite, in the carcass ply 24, the improvement in the heat resistance adhesion between the metal cord and the rubber composition and the improvement in the crack resistance of the rubber composition are achieved. It is possible to provide a heavy duty tire that realizes a high degree of compatibility and further prevents damage and further improves the durability of the entire tire.
When the carcass 14 is formed by laminating a plurality of carcass plies 24, the new metal cord-rubber composite is used for at least one carcass ply 24.

Next, the new metal cord-rubber composite used in this embodiment will be described in detail.
[Metal cord]
In the present embodiment, the metal cord used for the metal cord-rubber composite is formed by twisting a plurality of metal wires (metal steel wires) or a single wire of metal wires. The metal wire to be used is not particularly limited, and examples thereof include wires such as iron, steel (stainless steel), lead, aluminum, copper, brass, bronze, monel metal alloy, nickel, and zinc.

  Further, the metal wire preferably has a plating layer produced by a conventional method on the surface thereof, and the plating layer is not particularly limited. For example, a zinc plating layer, a copper plating layer, a brass (brass) plating layer is used. Among these, a brass (brass) plating layer is preferable from the viewpoint of initial adhesiveness with a rubber composition, wet heat adhesiveness, and formation of a suitable rubber metal adhesive layer.

  The bulk brass plating composition constituting this brass (brass) plating layer is 40 to 80% by mass of Cu (copper) and 20 to 20% of Zn (zinc) in terms of steel cord processability and adhesiveness to rubber. It is preferable that it is 60 mass%, More preferably, it is desirable that Cu is 55-70 mass% and Zn is 30-45 mass%.

  Thus, as a metal cord, it is a metal cord which consists of a single wire of the metal wire which gave brass plating to the peripheral surface, or is twisted together, Comprising: Brass plating composition is 40-80 mass% of Cu, Zn is 20 If the metal cord of ˜60 mass% is used, it is possible to provide a heavy-duty tire that can provide good workability of the metal cord and more suitable adhesion to the rubber composition of the metal cord.

  A steel wire is mentioned as a metal wire, and it demonstrates in detail. The steel wire is steel, that is, a linear metal containing iron as a main component (the mass of iron exceeds 50% by mass with respect to the total mass of the metal steel wire). The metal may include a metal other than iron described above.

  The steel wire preferably has a wire diameter of 0.1 mm to 5.5 mm, more preferably 0.15 mm to 5.26 mm, from the viewpoints of workability and durability. Here, the wire diameter of the steel wire refers to the longest length between two points on the outer periphery in a cross-sectional shape perpendicular to the axis of the steel wire. The cross-sectional shape perpendicular to the axis of the steel wire is not particularly limited, and may be elliptical, rectangular, triangular, polygonal, or the like, but is generally circular. In addition, when using a steel cord which is a metal reinforcing cord in which the steel wire is twisted on a carcass or a belt of a tire, the cross-sectional shape of the steel wire is circular, and the wire diameter is 0.1 mm to 0.5 mm. It is preferable to do. Moreover, it is preferable that this steel wire has the brass (brass) plating layer which becomes the said composition on the surface, Although the thickness of this plating layer is not specifically limited, For example, it is generally 100-300 nm.

  In this embodiment, for example, by twisting a plurality of metal wires such as steel wires having the brass plating on the peripheral surface, for example, by twisting them into a 1 × 3 structure, a 1 × 5 structure, etc. A metal cord made of a cord can be obtained.

  In the present embodiment, the N (nitrogen) atoms on the surface of the metal cord are treated as if they were left as a treat (coating the metal cord with an unvulcanized rubber composition and leaving it (treat) and then vulcanizing the metal cord. From the point of adhesion between the rubber composition and the rubber composition), and the Cu / Zn ratio needs to be 1 or more and 4 or less on a mass basis, preferably, The N atoms on the surface of the metal cord are preferably 2.1 atomic percent or more and 55.0 atomic percent or less, and the Cu / Zn ratio is preferably 1.1 or more and 3.5 or less.

  By setting the ratio of N atoms on the surface of the metal cord to 2 atomic% or more, the effect of this embodiment can be sufficiently obtained, and if it is less than 2 atomic%, the neglectability of the treat is deteriorated, and 60 atomic%. When it is excessive, the initial adhesiveness with rubber is deteriorated. Further, by setting the Cu / Zn ratio of the surface of the metal cord to 1 or more, the effect of the present embodiment can be sufficiently obtained, and if it is less than 1, the initial adhesiveness is not sufficient, and is 4 or less. The initial adhesiveness is good, and when it exceeds 4, the wet heat deterioration becomes insufficient.

  In this embodiment, adjustment of N (nitrogen) atoms on the surface of the metal cord to be 2 atomic% or more and 60 atomic% or less is, for example, treatment with a triazole compound (rust inhibitor), specifically, an aqueous solution with a triazole compound. The surface treatment such as contact with the metal cord can be suitably combined, and the adjustment of the Cu / Zn ratio on the surface of the metal cord to 1 or more and 4 or less is, for example, the pH of the acidic buffer solution or the triazole aqueous solution It can be performed by performing a process of suitably combining the concentrations. The lower the pH, the higher the Cu / Zn ratio metal cord can be obtained.

  Examples of the acidic buffer include an acetic acid buffer solution having a pH of 5.0 to 7.2, a phosphate buffer solution, and a citrate buffer solution, and preferably an acetic acid buffer solution having a pH of 5.0 to 7.2. It is done. When the pH is less than 5.0, the Cu / Zn ratio cannot be made 4 or less, and when the pH is over 7.2, the Cu / Zn ratio cannot be made 1 or more. The surface treatment time with this buffer solution can be set to 0.5 to 20 seconds, for example, when an acetate buffer solution with a pH of 5.0 to 7.2 is used.

  Examples of the triazole aqueous solution include 1,2,4-triazole, 1,2,3-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, and benzoate. Examples include aqueous solutions of one or more triazole compounds selected from triazole, tolyltriazole, and 3-mercapto-1,2,4-triazole, preferably 1,2,4-triazole, 1,2,3-triazole, 3 Use of -amino-1,2,4-triazole and 4-amino-1,2,4-triazole is desirable. The concentration of the aqueous triazole solution is preferably 0.01 to 20 g / L, and the treatment time varies depending on the concentration, but can be 0.1 to 30 seconds.

  Thus, the surface treatment with a buffer solution having a pH of 5.0 to 7.2 with respect to the metal cord, 1,2,4-triazole, 1,2,3-triazole, 3-amino-1,2,4 A metal with a treatment with one or more triazole compounds selected from triazole, 4-amino-1,2,4-triazole, benzotriazole, tolyltriazole, 3-mercapto-1,2,4-triazole It is possible to easily obtain a metal cord in which the N atom on the cord surface is 2 atomic percent to 60 atomic percent and the Cu / Zn ratio of the metallic cord surface is adjusted to 1 or more and 4 or less, and the durability is further improved. This makes it possible to provide a heavy-duty tire that is easy to manufacture.

  In the present embodiment, the “surface” of the metal cord is a surface layer region up to a depth of 5 nm on the inner side in the radial direction of the metal wire such as a steel wire. The measurement of N atoms on the surface of the metal cord and the measurement of the Cu / Zn ratio are carried out after obtaining the metal cord, and after washing, drying, etc., if necessary, before coating with the rubber composition. The surface of the metal cord is measured.

  In the present embodiment (including examples described later), the measurement of N atoms on the surface of the metal cord is performed on the surface of the metal cord measured by X-ray photoelectron spectroscopy (XPS). N atoms were measured, and the measurement of the Cu / Zn ratio on the surface of the metal cord was performed by measuring the Cu / Zn ratio on the surface of the metal cord by the photoelectron spectroscopy.

[Rubber composition for metal cord coating]
The rubber composition used for the coating rubber of the metal cord-rubber composite of the present embodiment is 1 to 15 parts by mass of silica and 0 (zero) or 1 part by mass or less of the cobalt-containing compound with respect to 100 parts by mass of the rubber component. Is included.

  The rubber component of the rubber composition used for the coated rubber is not particularly limited, and examples thereof include natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, and ethylene-propylene. Examples thereof include diene rubbers such as copolymer rubber, ethylene-propylene-diene terpolymer rubber, butyl rubber, halogenated butyl rubber, alkylated chlorosulfonated polyethylene rubber, isobutylene-isoprene copolymer rubber, and polychloroprene rubber. These rubber components may be used individually by 1 type, and may be used in combination of 2 or more types.

As will be described later, the silica used in the present embodiment is blended as a component that suppresses the progress of cracks and improves heat-resistant adhesion. Silica that can be used is not particularly limited, and those used in commercially available rubber compositions can be used, among which wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), colloidal silica, etc. are used. can do. As a particularly preferable silica, one having a BET specific surface area of 50 to 400 m ² / g is desirable. In the present embodiment, the BET specific surface area is measured by one point value of the BET method.

  The compounding amount of these silicas is 1 to 15 parts by mass, more preferably 1.5 parts by mass or more, particularly preferably 100 parts by mass of the rubber component, from the viewpoint of suppressing crack propagation and improving heat-resistant adhesion. Is 2 parts by mass or more.

  In the rubber composition used for the coated rubber of this embodiment, the cobalt-containing compound is 0 to 1 part by mass (0 (zero) or 1 part by mass or less) with respect to 100 parts by mass of the rubber component. Examples of the cobalt-containing compound that can be used include cobalt (a simple substance), a cobalt salt of an organic acid, a cobalt salt of an inorganic acid, and the like. For example, cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt citrate, glucone. Examples include cobalt acid, cobalt naphthenate, cobalt neodecanoate, cobalt stearate, cobalt rosinate, cobalt versatate, cobalt tall oil, cobalt borate neodecanoate, and acetylacetonate cobalt.

  Moreover, the composite salt which replaced a part of organic acid with boric acid etc. may be sufficient. The organic acid cobalt salt containing boron is cobalt orthoborate having a cobalt content of 20 to 23% by mass. Examples of commercially available products include Rhono Manobond C22.5 and Manobond 680C, Jhepherd CoMend A and CoMend B, Examples include YYNBC-II manufactured by Dainippon Ink & Chemicals, Inc.

  These cobalt-containing compounds are conventionally blended in the coated rubber composition of the metal cord-rubber composite as an adhesion promoter, but in this embodiment, the heat degradation resistance and crack growth resistance (resistance to resistance) From the viewpoint of improving (cracking property), the content of the cobalt-containing compound is 0 to 1 part by mass with respect to 100 parts by mass of the rubber component, that is, 0 (zero) or less than 1 part by mass (0 <content of cobalt-containing compound) Preferably, from the viewpoint of further improving the heat deterioration resistance and crack growth resistance, 0 (zero) or 0.1 parts by mass or less, particularly preferably cobalt. It is desirable that no compound is contained [0 (zero)]. This is because the addition of a cobalt-containing compound such as a cobalt salt may cause aging of the rubber component, which may be disadvantageous in terms of durability and strength, and cost. As a technique for greatly reducing the use of a cobalt salt in a coated rubber composition, for example, a brass-plated steel cord washed with a transition metal salt solution such as a cobalt salt may be used for the metal cord. In addition, in this embodiment, content of a cobalt containing compound says cobalt content conversion.

  Thus, when a rubber composition not containing a cobalt-containing compound is used, a carcass ply 24 having further excellent crack resistance can be obtained, and a heavy duty tire that can further improve durability can be obtained. Can be provided.

  In addition to the rubber component, silica, and the like, the coating rubber composition to be used may be appropriately blended with components normally employed in the rubber industry as long as the object of the present embodiment is not impaired. Examples of other components include vulcanizing agents such as sulfur, fillers such as carbon black, oils such as process oils, vulcanization accelerators, anti-aging agents, softeners, zinc oxide, and stearic acid. It is done. The rubber composition used in the present embodiment can be produced by kneading these components by a conventional method, followed by heating and extruding.

[Metal cord-Rubber composite]
The metal cord-rubber composite used in the present embodiment is manufactured by subjecting the plurality of metal cords subjected to the respective surface treatments to a cleaning treatment by a conventional method, if necessary, and then applying the metal cord to the coating. It can be manufactured through a step of adhering the rubber composition. By bonding the metal cord after each surface treatment and the rubber composition having the above characteristics, for example, the metal cord and the rubber composition can be produced by vulcanization adhesion under pressure and heating. Vulcanization conditions are not particularly limited, but the pressure is preferably 2 MPa to 15 MPa, more preferably 2 MPa to 5 MPa, and the temperature is preferably 120 to 200 ° C, more preferably 130 to 170 ° C. The vulcanization time is not particularly limited, but is preferably 3 minutes to 60 hours.

  The metal cord-rubber composite used in this embodiment configured as described above is excellent in both the heat resistance adhesion and crack growth resistance (crack resistance) between the metal cord and the rubber, and the metal cord and the rubber. Although there are some unclear points regarding the mechanism of whether the improvement in heat-resistant adhesion and the improvement in crack growth resistance can be achieved at a high level, it is presumed as follows.

  That is, the metal cord-rubber composite used in the present embodiment is a metal cord-rubber composite formed by coating a rubber composition with a metal cord, and the number of N atoms on the surface of the metal cord is 2 atom% or more and 60 atoms. %, And the Cu / Zn ratio is 1 or more and 4 or less, and 1 to 15 parts by mass of silica and 0 to 1 part by mass of a cobalt-containing compound with respect to 100 parts by mass of the rubber component of the rubber composition. In addition, the rubber composition containing silica is less likely to generate fracture nuclei in the rubber and suppresses the progress of cracks, while silica adsorbs components that break the rubber-metal bonding interface in the rubber, and so on. By increasing the adhesion, and by using metal cords with N atoms on the surface of the metal cord and a Cu / Zn ratio in a specific range, the heat-resistant adhesion is further improved. And metals of birth synergy effect of improving the enhancing effect and heat resistant adhesion of the adhesive, is inferred to be due to the effect of exceeding the above sum of the effects of the individual techniques are exhibited.

  Next, the metal cord-rubber composite used for the carcass ply 24 of the heavy duty tire of this embodiment will be described based on examples and comparative examples.

[Examples 1-2 and Comparative Examples 1-4]
(Production of metal cord)
A steel cord (metal cord) having a 1 × 3 structure was manufactured by twisting steel wires (plating layer thickness 0.2 μm, wire diameter 0.3 mm) subjected to brass plating having the composition shown in Table 1 below. Next, this code is washed with a treatment solution consisting of the following treatment method: treatment buffer solution or phosphate treatment solution, treatment 2: rust inhibitor (triazole compound), and dried at 50 ° C. for 1 minute. I let you. The N amount (outermost surface N amount: atomic%) and the Cu / Zn ratio (outermost surface Cu / Zn ratio) on the wire plating surface of the steel cord after the cleaning treatment were measured using an X-ray photoelectron spectrometer (ULVAC-PHI Co., Ltd.). The results are shown in Table 1 below.

  The measurement conditions by X-ray photoelectron spectroscopy are as follows.

X-ray source: Monochromatic Al-Kα ray Measurement area: 50 μmΦ
Measurement peak: C1s, O1s, N1s, P2p, Cu2p2 / 3, Zn2p2 / 3
Data processing: Multipak (manufactured by ULVAC-PHI)
Quantification: Quantification using the relative sensitivity coefficient method from the obtained peak area * Cu / Zn is the ratio of the quantitative values of Cu2p2 / 3 and Zn2p2 / 3.

[Treatment 1: Treatment with acetate buffer]
The treatment with the acetic acid buffer solution was performed by using a treatment solution prepared by adjusting 0.1N sodium acetate with acetic acid so as to have the pH shown in Table 1, and washing the produced steel cord with a treatment time of 10 seconds to perform surface treatment. It was.

[Treatment 2: Treatment with triazole compound (rust inhibitor)]
The treatment with the triazole compound (rust inhibitor) is performed by washing the steel cord produced using a triazole compound aqueous solution adjusted to have each concentration using each triazole compound shown in Table 1 for a treatment time of 10 seconds. Processed.

  Using the steel cord after the above washing treatment, using the rubber composition of the formulation shown in Table 1 below, the heat resistance adhesiveness (index indication) and the crack resistance which are evaluated for each cord / rubber adhesiveness by the following methods Growth potential (index indication) was evaluated. These results are shown in Table 1 below.

(Evaluation method for heat-resistant adhesion)
The washed steel cords are arranged in parallel at an interval of 12.5 mm, and the steel cords are covered with a rubber composition from above and below, and vulcanized at 145 ° C. for 80 minutes to adhere the rubber composition and the steel cord. It was. In this manner, a metal cord-rubber composite in which a steel cord was embedded in a rubber sheet having a thickness of 1 mm was obtained (the steel cords are arranged at 12.5 mm intervals in the center in the thickness direction of the rubber sheet. ).

  After this metal cord-rubber composite was deteriorated for 7 days in an atmosphere of 80 ° C. and 40% relative humidity, the steel cord was pulled out from each sample in accordance with ASTM D 2229, and the rubber attached to the steel cord was removed. The coverage was determined by visual observation from 0 to 100%, and was used as an indicator of wet heat degradation. The results are shown as an index in Table 1 below, with Comparative Example 1 taken as 100. It shows that it is excellent in heat-resistant adhesiveness, so that an index value is large.

(Evaluation method of crack growth resistance)
For evaluation of crack growth resistance (crack resistance), each sample was subjected to a constant stress fatigue test using a fatigue tester manufactured by Ueshima Seisakusho Co., Ltd., and the number of times until fracture was measured. The results are shown as an index in Table 1 below with Comparative Example 1 as 100. It shows that it is excellent in crack growth resistance, so that a numerical value is large.

* 1 to * 6 in Table 1 are as follows.
* 1: Product name “IR2200” manufactured by JSR
* 2: Tokai Carbon Co., Ltd., trade name “Seast 3 (N ₂ SA: 79 m / g, 24M4DBP
^Absorption: 102m 3 / 100g). "
* 3: Product name “Nip Seal AQ” manufactured by Tosoh Silica
* 4: Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 6C”, N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine * 5: Ouchi Shinsei Chemical Co., Ltd. ), Trade name “Noxeller DZ”, N, N′-dicyclohexyl-2-benzothiazolylsulfenamide * 6: trade name “Manobond C22.5”, cobalt content 22.5 mass%

  As is apparent from Table 1 above, the metal cord-rubber composites of Examples 1 and 2 that fall within the scope of the present embodiment are more resistant to heat than those of Comparative Examples 1 to 4 that fall outside the scope of the present embodiment. Moreover, it was excellent in crack growth resistance, and the effect of this embodiment could be confirmed.

  Specifically, in Examples 1-2, the silica content of the coated rubber composition was varied within the range of the present embodiment, and the amount of N atom on the surface of the metal cord, Cu / Zn ratio is in the range of this embodiment, and the composition of the coated rubber composition is a metal cord-rubber composite in the range of this embodiment. It was confirmed that the effects of the embodiment can be exhibited.

  On the other hand, looking at the comparative example, the comparative example 1 shows that the N atomic weight on the surface of the metal cord and the Cu / Zn ratio are out of the range of the present embodiment, and the composition of the coated rubber composition is within the range of the present embodiment. It is a metal cord-rubber composite that is external (no silica compounding). In Comparative Examples 2 and 3, the composition of the coated rubber composition is out of the range of the present embodiment even when the N atomic weight on the surface of the metal cord and the Cu / Zn ratio are within the range of the present embodiment (no silica compounding). This is a metal cord-rubber composite. Comparative Example 4 is a metal cord-rubber composite in which the N atomic weight and Cu / Zn ratio on the surface of the metal cord are outside the range of the present embodiment even when the composition of the coated rubber composition is within the range of the present embodiment. It is. It was confirmed that these Comparative Examples 1 to 4 cannot exhibit the effects of the present embodiment.

  In particular, Comparative Example 1 (the metal cord and the coated rubber composition are outside the scope of the present embodiment), Comparative Examples 2 and 3 (the coated rubber composition is outside the scope of the present embodiment), and Comparative Example 4 (the metal cord is implemented in the present embodiment). Each metal cord-rubber composite of Examples 1 and 2 that falls within the scope of the present embodiment in consideration of evaluation of heat-resistant adhesion and crack growth resistance of each metal cord-rubber composite Comparative evaluation of the heat-resistant adhesion and crack growth resistance of Examples 1 and 2 that are within the scope of the present embodiment for any of the comparative examples can confirm that a remarkable effect is produced. It was.

  Then, by using Examples 1 and 2 of the metal cord-rubber composite for the carcass ply 24, in the carcass ply 24, improvement in heat resistance adhesion between the metal cord and the rubber composition and crack resistance of the rubber composition were achieved. It was confirmed that it was possible to further prevent damage by realizing a higher degree of compatibility with the improvement of the tire and to further improve the durability of the entire tire.

(Modification 1)
In the above-described embodiment, the above-described new metal cord-rubber composite is used for the carcass 14 (carcass ply 24). However, in the first modification, the belts 16a to 16f of the belt layer 16 are also provided with this new metal cord-rubber composite. A metal cord-rubber composite is used. Among the carcass 14 (carcass ply 24), the belt layer 16 (belts 16a to 16f), and the reinforcing band 17 (wire chafer 27), the belt layer 16 (belts 16a to 16f) is connected to the carcass 14 (carcass ply 24). Next, the contribution to durability improvement for the entire tire is large. Therefore, in the belts 16a to 16f, a high degree of compatibility between the improvement of the heat resistance adhesion between the metal cord and the rubber composition and the improvement of the crack resistance of the rubber composition greatly affects the durability improvement effect of the tread portion in particular. This contributes greatly to improving the durability of the entire tire. In the belt layer 16, this new metal cord-rubber composite may be used for at least one belt.

  Thus, in addition to the carcass ply 24, the heavy duty tire that can further improve the durability of the entire tire by using the new metal cord-rubber composite for the belts 16a to 16f. Can be provided.

(Modification 2)
In the above-described modified example 1, the above-described new metal cord-rubber composite is used for the carcass ply 24 and the belts 16a to 16f. However, in the modified example 2, the wire chafer 27 of the reinforcing band 17 is also used. A new metal cord-rubber composite is used. When the reinforcing band 17 is formed by laminating a plurality of wire chafers 27, the new metal cord-rubber composite is used for at least one wire chafer 27.

  As with the carcass ply 24 and the belts 16a to 16f, the wire chafer 27 using this new metal cord-rubber composite is improved in heat resistance adhesion between the metal cord and the rubber composition and crack-resistant in the rubber composition. It is possible to achieve a higher level of compatibility with the improvement of performance. In particular, this contributes to improving the durability of the bead portion 13 against a thermal load and a physical load received from the rim. Therefore, by using this new metal cord-rubber composite for the wire chafer 27 in addition to the carcass ply 24 and the belts 16a to 16f, the durability of the entire tire is further improved compared to the first modification. Thus, it is possible to provide a heavy duty tire that can be applied.

  Note that the above-described new metal cord-rubber composite may be used for the carcass ply 24 and the wire chafer 27 without being used for the belts 16a to 16f. In this case, it is possible to provide a heavy duty tire that can further improve the durability of the entire tire as compared with the above-described embodiment.

  As mentioned above, although embodiment of this invention was described, these embodiment is only the illustration described in order to make an understanding of this invention easy, and this invention is not limited to the said embodiment. The technical scope of the present invention is not limited to the specific technical matters disclosed in the above embodiment, but includes various modifications, changes, alternative techniques, and the like that can be easily derived therefrom.

DESCRIPTION OF SYMBOLS 10 Heavy load tire 11 Tread part 11a Tread surface 12 Side wall part 13 Bead part 14 Carcass 14a Crown part 14b Rewinding part 15 Bead core 16 Belt layer 16a 1st belt 16b 2nd belt 16c 3rd belt 16d 4th belt 16e 5th belt 16f 6th belt 17 Reinforcement belt 24 Carcass ply 24b Rewind part 27 Wire chafer

Claims (6)

A pair of tread portions, a pair of sidewall portions that are continuous to both ends of the tread portion, a pair of bead portions in which a bead core is embedded and continuous to the sidewall portion, and a rewinding portion that is wound around the bead core. A heavy duty tire provided with a carcass extending in a toroidal shape between the bead parts,
The carcass is formed by at least one carcass ply;
At least one carcass ply is formed of a metal cord-rubber composite formed by coating a rubber composition on each of a plurality of metal cords,
The metal cord has a surface N atom of 2 atomic% or more and 60 atomic% or less, and a Cu / Zn ratio of the surface of 1 or more and 4 or less, and the rubber composition is based on 100 parts by mass of a rubber component, A heavy-duty tire comprising 1 to 15 parts by mass of silica and 0 to 1 part by mass of a cobalt-containing compound. A belt layer disposed between the carcass and the tread portion;
The belt layer is formed by a plurality of laminated belts,
The heavy duty tire according to claim 1, wherein at least one of the belts is formed of the metal cord-rubber composite. A reinforcing band disposed on the side opposite to the bead core side of the winding portion in the carcass;
The reinforcing band is formed by at least one wire chafer,
3. The heavy duty tire according to claim 1, wherein at least one of the wire chafers is formed of the metal cord-rubber composite.   The metal cord is a metal cord made of a single wire of a metal wire with brass plating applied to the peripheral surface or a plurality of twisted wires, and the brass plating composition is 40 to 80% by mass of Cu and 20 to 60% of Zn. The heavy-duty tire according to any one of claims 1 to 3, wherein the tire is a mass%.   The metal cord is prepared by surface treatment with a buffer solution having a pH of 5.0 to 7.2, 1,2,4-triazole, 1,2,3-triazole, 3-amino-1,2,4-triazole, 4 A treatment with at least one triazole compound selected from amino-1,2,4-triazole, benzotriazole, tolyltriazole, and 3-mercapto-1,2,4-triazole. The heavy duty tire according to any one of 1 to 4.   The heavy duty tire according to any one of claims 1 to 5, wherein the rubber composition does not contain a cobalt-containing compound.

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