Tire cord and method for manufacturing same

Abstract

This tire cord 10 is provided with at least one strand 11. The strand 11 includes: at least one filament bundle 12; a first coating 13 that is disposed so as to cover at least part of a surface of the filament bundle 12; and a second coating 14 that is disposed over the first coating 13. The filament bundle 12 includes at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments. The first coating 13 includes a cured epoxy resin. The second coating 14 includes a resorcinol–formaldehyde condensate and a rubber constituent. The tire cord has a three-point flexural modulus of at least 100 MPa.

Description

Tire cord and manufacturing method thereof

[0001] The present invention relates to a tire cord and a method for producing the same.

[0002] For reinforcement, a belt member is provided in the circumferential direction of a tire at the portion where the tire comes into contact with the road, between a member forming the tire's framework (e.g., a carcass) and the surface of the tire that comes into contact with the road. This belt member is required to have high belt rigidity, so reinforcing cords are provided inside.

[0003] As disclosed in Patent Document 1, steel cords have conventionally been used as cords for realizing belt members with high rigidity. Steel cords are extremely advantageous in that they can improve the operational stability and abrasion resistance of tires.

[0004] Japanese Patent Application Publication No. 5-8609

[0005] However, with steel cord, the high specific gravity of steel makes the belt member heavy. As a result, tires with belt members using steel cord have problems such as poor rolling resistance, a tendency for standing waves to occur due to increased centrifugal force during driving, and poor high-speed durability. Standing waves occur when a tire makes a full rotation before returning to its original shape after making contact with the road, resulting in an imbalance between the force of the road surface trying to dent the tire and the force trying to return the tire to its original shape.

[0006] Furthermore, because steel is a metallic material, tires equipped with belt members using steel cords have had the problem that rust occurs on the steel when rainwater or the like gets into the tire, leading to tire destruction.

[0007] In order to solve the above problems, it has been considered to use cords made of glass fiber, carbon fiber, or the like, which have conventionally been used as rubber reinforcing cords, as tire cords for belt members, instead of steel cords. However, conventional rubber reinforcing cords do not have sufficient bending rigidity compared to steel cords, and therefore tires using conventional rubber reinforcing cords have insufficient steering stability and wear resistance compared to tires using steel cords. Furthermore, because the bending rigidity of the belt in the contact patch during cornering is not high enough, sufficient cornering force (lateral force generated by the vehicle tires during cornering) is not generated, and the steering performance is also inferior.

[0008] Therefore, one object of the present invention is to provide a tire cord that can realize a tire belt member having bending rigidity equal to or higher than that of a tire belt member using a steel cord, and that can also realize excellent adhesion to rubber. Furthermore, another object of the present invention is to provide a method for producing such a tire cord.

[0009] In one aspect, the present invention provides a tire cord for reinforcing a tire, the tire cord comprising at least one strand, the strand comprising: at least one filament bundle; a first coating provided so as to cover at least a portion of the surface of the filament bundle; and a second coating provided on the first coating, the filament bundle comprising at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, the first coating comprising a cured product of an epoxy resin, and the second coating comprising a resorcinol-formaldehyde condensate and a rubber component, the tire cord having a three-point bending modulus of elasticity of 100 MPa or more as determined by the following three-point bending measurement method. Three-point bending measurement method: (1) Prepare a test specimen in which 20 of the tire cords are embedded inside a matrix rubber having the composition shown in Table 1 below. Here, the test specimen has a rectangular parallelepiped shape with a width (W) of 25 mm, a length of 120 mm, and a height (h) of 4 mm. The 20 tire cords have a length of 110 mm. In the test specimen, the length direction of each tire cord is aligned with the length direction of the test specimen, and the 20 tire cords are arranged at regular intervals in the width direction of the test specimen. (2) At 23°C, a three-point bending measurement is performed on the test specimen with a support distance (Lv) of 30 mm and a bending speed of 5 mm / min to determine a bending load-deflection curve. (3) For the bending load-deflection curve, the gradient (change in bending load (ΔF) / change in bending deflection (ΔY)) at a bending deflection of 1.5 mm to 2.5 mm is determined, and the three-point bending modulus is calculated using the gradient according to the following formula (I). Formula (I): Three-point bending modulus (MPa) = (Lv 3 / 4Wh 3 ) × (ΔF / ΔY)

[0010] From another aspect, the present invention provides a method for producing a tire cord according to the above-described invention, the method comprising: (a) bundling a plurality of filaments, each including at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, to produce at least one filament bundle; (b) forming a first coating so as to cover at least a portion of the surface of the filament bundle; and (c) forming a second coating on the first coating, wherein in (b), a first treatment agent containing an epoxy resin and a curing agent is supplied to at least a portion of the surface of the filament bundle, and the epoxy resin is cured to form the first coating; and in (c), a second treatment agent containing a resorcinol-formaldehyde condensate and rubber latex is supplied to the first coating of a precursor cord in which the first coating has been formed on at least a portion of the surface of the filament bundle, and the second coating is formed by drying the second treatment agent.

[0011] According to the present invention, it is possible to provide a tire cord that can realize a tire belt member having bending rigidity equal to or higher than that of a tire belt member using a steel cord, and that can also realize excellent adhesion to rubber. Furthermore, according to the present invention, it is possible to provide a method for producing such a tire cord.

[0012] Fig. 1 is a cross-sectional view schematically showing an example of a tire cord according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing an example of a belt member provided with the tire cord shown in Fig. 1. Fig. 3 is a perspective view showing an example of an airless tire, which is an example of a tire in which the tire cord according to an embodiment of the present invention is used. Fig. 4 is a cross-sectional view of a shear band provided in the airless tire shown in Fig. 3. Fig. 5 is a schematic view showing the shape of a test specimen prepared for measuring the adhesive strength of the tire cords of Examples and Comparative Examples.

[0013] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0014] (One Aspect of the Present Invention) A tire cord according to a first aspect of the present invention is a tire cord for reinforcing a tire, the tire cord comprising at least one strand, the strand comprising: at least one filament bundle; a first coating provided so as to cover at least a portion of the surface of the filament bundle; and a second coating provided on the first coating, the filament bundle comprising at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, the first coating comprising a cured product of an epoxy resin, and the second coating comprising a resorcinol-formaldehyde condensate and a rubber component, the tire cord having a three-point bending modulus of elasticity of 100 MPa or more as determined by the following three-point bending measurement method. Three-Point Bending Measurement Method: (1) A test specimen is prepared in which 20 of the tire cords are embedded inside a matrix rubber having the composition shown in Table 1 above. Here, the test specimen has a rectangular parallelepiped shape with a width (W) of 25 mm, a length of 120 mm, and a height (h) of 4 mm. The 20 tire cords have a length of 110 mm. In the test specimen, the length direction of each tire cord is aligned with the length direction of the test specimen, and the 20 tire cords are arranged at regular intervals in the width direction of the test specimen. (2) At 23°C, a three-point bending measurement is performed on the test specimen with a support distance (Lv) of 30 mm and a bending speed of 5 mm / min to determine a bending load-deflection curve. (3) For the bending load-deflection curve, the gradient (change in bending load (ΔF) / change in bending deflection (ΔY)) at a bending deflection of 1.5 mm to 2.5 mm is determined, and the three-point bending modulus is calculated using the gradient according to the following formula (I). Formula (I): Three-point bending modulus (MPa) = (Lv 3 / 4Wh 3 ) × (ΔF / ΔY)

[0015] In a second aspect of the present invention, for example, in the tire cord according to the first aspect, a content ratio of the first coating in the tire cord may be 15% by mass or more and 50% by mass or less.

[0016] In a third aspect of the present invention, for example, in the tire cord according to the first or second aspect, the content of the second coating in the tire cord may be more than 0% by mass and 5% by mass or less.

[0017] In a fourth aspect of the present invention, for example, in the tire cord according to any one of the first to third aspects, the filament bundles may include the glass fiber filaments, and a mass ratio of the glass fiber filaments in the tire cord may be 50 mass% or more and 80 mass% or less.

[0018] In a fifth aspect of the present invention, for example, in the tire cord according to any one of the first to third aspects, the filament bundles may include the carbon fiber filaments, and a mass ratio of the carbon fiber filaments in the tire cord may be 40 mass% or more and 70 mass% or less.

[0019] In a sixth aspect of the present invention, for example, in the tire cord according to any one of the first to fifth aspects, the cured product of the epoxy resin may be a reaction product of the epoxy resin and a curing agent, and a mass ratio of the epoxy resin to a total of the epoxy resin and the curing agent may be 40 mass % or more and 95 mass % or less.

[0020] In a seventh aspect of the present invention, for example, in the tire cord according to any one of the first to sixth aspects, the filament bundle may be untwisted.

[0021] In an eighth aspect of the present invention, for example, in the tire cord according to any one of the first to seventh aspects, the strand is configured with one filament bundle, the first coating, and the second coating, and the filament bundle may be untwisted.

[0022] In the ninth aspect of the present invention, for example, the tire cord according to the eighth aspect may include one strand.

[0023] In a tenth aspect of the present invention, for example, the tire cord according to any one of the first to ninth aspects may be embedded in a belt member of a tire.

[0024] A method for producing a tire cord according to an eleventh aspect of the present invention is the method for producing a tire cord according to any one of the first to tenth aspects, comprising: (a) bundling a plurality of filaments including at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments to produce at least one filament bundle; (b) forming a first coating so as to cover at least a portion of the surface of the filament bundle; and (c) forming a second coating on the first coating, wherein in (b), a first treatment agent including an epoxy resin and a curing agent is supplied to at least a portion of the surface of the filament bundle, and the epoxy resin is cured to form the first coating; and in (c), a second treatment agent including a resorcinol-formaldehyde condensate and rubber latex is supplied to the precursor cord in which the first coating has been formed on at least a portion of the surface of the filament bundle, and the second coating is formed by drying the second treatment agent.

[0025] In a twelfth aspect of the present invention, for example, in the manufacturing method according to the eleventh aspect, in (b), the tire cord may be supplied so that a content ratio of the first coating in the tire cord is 15% by mass or more and 50% by mass or less.

[0026] In a thirteenth aspect of the present invention, for example, in the manufacturing method according to the eleventh or twelfth aspect, in (c), the second treatment agent may be supplied so that the content of the second coating in the tire cord is more than 0 mass % and not more than 5 mass %.

[0027] In a fourteenth aspect of the present invention, for example, in the production method according to any one of the eleventh to thirteenth aspects, in the first treatment agent, a mass ratio of the epoxy resin to a total of the epoxy resin and the curing agent may be 40 mass % or more and 95 mass % or less.

[0028] (Embodiment of the Invention) A tire cord according to an embodiment of the invention will be described.

[0029] The tire cord of this embodiment includes at least one strand. The strand includes at least one filament bundle, a first coating provided so as to cover at least a portion of the surface of the filament bundle, and a second coating provided on the first coating. The filament bundle includes at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments. The first coating includes a cured product of an epoxy resin. The second coating includes a resorcinol-formaldehyde condensate and a rubber component. The tire cord of this embodiment has a three-point bending modulus of elasticity of 100 MPa or more, as determined by the following three-point bending measurement method.

[0030] Three-Point Bending Measurement Method: (1) A test specimen is prepared in which 20 of the tire cords are embedded in a matrix rubber having the composition shown in Table 1 above. The test specimen has a rectangular parallelepiped shape with a width (W) of 25 mm, a length of 120 mm, and a height (h) of 4 mm. The 20 tire cords are 110 mm long. In the test specimen, the length direction of each tire cord is aligned with the length direction of the test specimen, and the 20 tire cords are arranged at regular intervals across the width direction of the test specimen. (2) Three-point bending measurement is performed on the test specimen at 23°C with a support distance (Lv) of 30 mm and a bending speed of 5 mm / min to obtain a bending load-deflection curve. (3) The gradient (change in bending load (ΔF) / change in bending deflection (ΔY)) from 1.5 mm to 2.5 mm of bending deflection is determined for the bending load-deflection curve, and the three-point bending modulus is calculated using this gradient according to the following formula (I):

[0031] Formula (I): Three-point bending elastic modulus (MPa) = (Lv 3 / 4Wh 3 ) × (ΔF / ΔY)

[0032] With the above-described configuration, the tire cord of the present embodiment can realize a tire belt member having a bending rigidity equal to or higher than that of a tire belt member using a steel cord that has been generally used as a conventional tire cord, and can also realize excellent adhesion to rubber. Note that the bending rigidity of the tire cord of the present embodiment described below means the bending rigidity of a tire belt member using the tire cord of the present embodiment.

[0033] The three-point bending modulus of the tire cord of this embodiment may be 150 MPa or more, or 200 MPa or more, thereby enabling the tire cord of this embodiment to achieve higher bending rigidity.

[0034] The upper limit of the three-point bending elastic modulus of the tire cord of this embodiment is not particularly limited, but is, for example, 500 MPa or less.

[0035] FIG. 1 is a cross-sectional view schematically illustrating an example of a tire cord according to the present embodiment. As an example, FIG. 1 illustrates a tire cord having one strand, where the strand includes one filament bundle. The tire cord 10 illustrated in FIG. 1 is composed of one strand 11. The strand 11 includes one filament bundle 12, a first coating 13 provided so as to cover at least a portion of the surface of the filament bundle 12, and a second coating 14 provided on the first coating 13. Note that the material constituting the first coating 13 may be completely or partially permeated into the filament bundle 12. In other words, the component indicated by the reference numeral 12 in FIG. 1 may include the filament bundle and the material of the first coating.

[0036] The tire cord of this embodiment is not limited to the configuration shown in Fig. 1. The tire cord of this embodiment may include a plurality of strands. Furthermore, each strand may include a plurality of filament bundles.

[0037] The tire cord of this embodiment will be described in more detail below.

[0038] In the tire cord of this embodiment, the filament bundle constituting the strand includes a plurality of filaments. As described above, the filament bundle includes at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments. The filament bundle may include glass fiber filaments.

[0039] The glass of the glass fiber filaments may be, for example, C-glass (alkali glass), E-glass (non-alkali glass), borosilicate glass, quartz glass, or high-elasticity glass such as U-glass, K-glass, and M-glass.

[0040] As the carbon fiber of the carbon fiber filament, PAN-based carbon fiber or pitch-based carbon fiber can be used.

[0041] In this embodiment, the filament bundle may contain glass fiber filaments as a main component, or may consist essentially of glass fiber filaments. Here, "the filament bundle contains glass fiber filaments as a main component" means that the filaments that account for the largest proportion of the cross-sectional area of ​​the filament bundle are glass fiber filaments. In this case, the proportion of glass fiber filaments in the cross-sectional area of ​​the filament bundle may be, for example, 50% or more. Furthermore, "the filament bundle is essentially made up of glass fiber filaments" means that the proportion of glass fiber filaments in the cross-sectional area of ​​the filament bundle is 90% or more, and may be, for example, 95% or more or 99% or more. The filament bundle may consist solely of glass fiber filaments.

[0042] In this embodiment, the filament bundle may contain carbon fiber filaments as a main component, or may consist essentially of carbon fiber filaments. Here, "the filament bundle contains carbon fiber filaments as a main component" means that the filaments that account for the largest proportion of the cross-sectional area of ​​the filament bundle are carbon fiber filaments. In this case, the proportion of carbon fiber filaments in the cross-sectional area of ​​the filament bundle may be, for example, 40% or more. Furthermore, "the filament bundle is essentially made of carbon fiber filaments" means that the proportion of carbon fiber filaments in the cross-sectional area of ​​the filament bundle is 90% or more, and may be, for example, 95% or more or 99% or more. The filament bundle may consist solely of carbon fiber filaments.

[0043] There is no particular limitation on the number of filaments contained in the filament bundle. The filament bundle may contain, for example, 800 to 8,000 filaments. Preferably, the filament bundle may contain 1,000 to 4,000 filaments. More preferably, the filament bundle may contain 2,000 to 4,000 filaments.

[0044] The thickness of the filament bundle may be, for example, 550 tex or more and 4800 tex or less. By providing a filament bundle of such a thickness, the tire cord of this embodiment can achieve higher bending rigidity.

[0045] There is no limitation on the number of filament bundles included in a tire cord, and it may be one as in the example shown in FIG. 1 , or it may be multiple. The filament bundle may be a bundle of multiple filament bundles. In this case, each of the multiple filament bundles may or may not be twisted. Furthermore, the multiple filament bundles may or may not be twisted together.

[0046] To achieve a higher flexural modulus, the filament bundles are preferably untwisted.

[0047] The mass proportion of the filament bundle in the tire cord of this embodiment is desirably set within an appropriate range in consideration of the balance between the mass proportion of the first coating and the mass proportion of the second coating, in order to achieve both higher bending rigidity in the tire cord and improved adhesion to rubber.

[0048] When the filament bundle contains glass fiber filaments, the mass proportion of the glass fiber filaments in the tire cord is preferably 50% by mass or more and 80% by mass or less. By having a mass proportion of the glass fiber filaments of 50% by mass or more, the tire cord of this embodiment can achieve higher bending rigidity. By having a mass proportion of the glass fiber filaments of 80% by mass or less, the first coating can be provided at a mass proportion sufficient to achieve high bending rigidity, thereby achieving higher bending rigidity. In other words, by setting the mass proportion of the glass fiber filaments within the range of 50% by mass or more and 80% by mass or less, it is possible to obtain the effects of both improving bending rigidity due to the filament bundle and improving bending rigidity due to the first coating.

[0049] When the filament bundle contains carbon fiber filaments, the mass proportion of the carbon fiber filaments in the tire cord is preferably 40% by mass or more and 70% by mass or less. When the mass proportion of the carbon fiber filaments is 40% by mass or more, the tire cord of this embodiment can achieve higher bending rigidity. When the mass proportion of the carbon fiber filaments is 70% by mass or less, the first coating can be provided in a mass proportion sufficient to obtain high bending rigidity, thereby achieving higher bending rigidity. In other words, by setting the mass proportion of the carbon fiber filaments within the range of 40% by mass or more and 70% by mass or less, it is possible to obtain the effects of both improving bending rigidity due to the filament bundle and improving bending rigidity due to the first coating.

[0050] The mass proportion of the glass fiber filaments in a tire cord can be determined, for example, using the mass value of the entire tire cord and the mass of the glass fiber filaments measured by extracting only the glass fiber filaments from the tire cord. The glass fiber filaments can be determined, for example, by removing components other than the glass fiber filaments (the first coating and the second coating) by heat treatment. The mass proportion of the carbon fiber filaments in a tire cord can be determined in the same manner.

[0051] The first coating is provided so as to cover at least a part of the surface of the filament bundle. Note that the first coating may be provided directly on the surface of the filament bundle, for example.

[0052] The first coating may be provided so as to cover a portion of the surface of the filament bundle, but in order to achieve higher bending rigidity, it is preferable that the first coating cover the entire surface of the filament bundle.

[0053] As described above, the first coating is a coating containing a cured epoxy resin. The first coating may contain the cured epoxy resin as a main component, or may consist essentially of the cured epoxy resin. Here, "the first coating contains the cured epoxy resin as a main component" means that the cured epoxy resin is the largest component in the first coating in terms of mass percentage. In this case, the mass percentage of the cured epoxy resin in the first coating may be, for example, 50 mass% or more. Furthermore, "the first coating consists essentially of the cured epoxy resin" means that the mass percentage of the cured epoxy resin in the first coating is 90 mass% or more, and may be, for example, 95 mass% or more or 99 mass% or more. The first coating may consist of a cured epoxy resin.

[0054] The cured epoxy resin is a reaction product of the epoxy resin and the curing agent. The mass ratio of the epoxy resin to the total mass of the epoxy resin and the curing agent is, for example, 40 mass % or more and 95 mass % or less. This allows the tire cord of this embodiment to achieve higher bending rigidity.

[0055] The epoxy resin used in the first coating is not particularly limited, and examples thereof include volac-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, brominated epoxy resins, bisphenol AD-type epoxy resins, and glycidylamine-type epoxy resins.

[0056] The curing agent used in the first coating is not particularly limited, and may be, for example, a known curing agent for epoxy resins, such as an amine-based curing agent, an acid anhydride-based curing agent, a polyamide resin-based curing agent, an imidazole-based curing agent, a phenol-based curing agent, etc. As the amine-based curing agent, for example, a modified aromatic amine may also be used.

[0057] In the tire cord of this embodiment, the content ratio of the first coating may be, for example, 15% by mass or more and 50% by mass or less. When the content ratio of the first coating satisfies the above range, the tire cord of this embodiment can achieve higher bending rigidity. When the content ratio of the first coating is 15% by mass or more, the tire cord of this embodiment can achieve higher bending rigidity. When the content ratio of the first coating is 50% by mass or less, the filament bundle can be provided at a mass ratio sufficient to obtain high bending rigidity, thereby achieving higher bending rigidity. In other words, when the content ratio of the first coating is within the range of 15% by mass or more and 50% by mass or less, it is possible to obtain the effects of both improving bending rigidity by the first coating and improving bending rigidity by the filament bundle.

[0058] When the first coating is a coating made of a cured epoxy resin, the content of the first coating described above refers to the content of the cured epoxy resin in the tire cord of this embodiment. Therefore, in the tire cord of this embodiment, the content of the cured epoxy resin may be, for example, 15% by mass or more and 50% by mass or less. When the content of the cured epoxy resin in the tire cord of this embodiment is 15% by mass or more, the tire cord of this embodiment can achieve higher bending rigidity. When the content of the cured epoxy resin is 50% by mass or less, the filament bundle can be provided at a mass ratio sufficient to achieve high bending rigidity, thereby achieving higher bending rigidity. In other words, by setting the content of the cured epoxy resin within the range of 15% by mass or more and 50% by mass or less, it is possible to obtain both the effects of improving bending rigidity due to the cured epoxy resin and the effects of improving bending rigidity due to the filament bundle.

[0059] The first coating is formed, for example, by supplying a first treatment agent described below to at least a portion of the surface of the filament bundle and drying it by heat treatment. Supplying the first treatment agent to the surface of the filament bundle can be performed, for example, by impregnating the filament bundle with the first treatment agent or by applying the first treatment agent to at least a portion of the surface of the filament bundle.

[0060] The second coating is provided on the first coating. Note that the second coating may be provided, for example, in contact with the first coating.

[0061] The second coating may be provided so as to cover a portion of the surface of the first coating, but in order to improve adhesion to rubber, it is preferable that the second coating cover the entire surface of the first coating.In order to further improve adhesion to rubber, it is preferable that the second coating cover the entire surface of the tire cord.

[0062] As described above, the second coating is a coating containing a resorcinol-formaldehyde condensate and a rubber component. The second coating may contain a resorcinol-formaldehyde condensate and a rubber component as main components, or may consist essentially of a resorcinol-formaldehyde condensate and a rubber component. Here, "the second coating contains a resorcinol-formaldehyde condensate and a rubber component as main components" means that the total mass of the resorcinol-formaldehyde condensate and the rubber component is the largest component in the second coating. In this case, the total mass of the resorcinol-formaldehyde condensate and the rubber component in the second coating may be, for example, 50% by mass or more. Furthermore, the phrase "the second coating consists essentially of a resorcinol-formaldehyde condensate and a rubber component" means that the total mass of the resorcinol-formaldehyde condensate and the rubber component in the second coating is 90% by mass or more, and may be, for example, 95% by mass or more or 99% by mass or more. The second coating may consist of a resorcinol-formaldehyde condensate and a rubber component.

[0063] In the tire cord of this embodiment, the content ratio of the second coating may be, for example, greater than 0% by mass and not greater than 5% by mass. When the content ratio of the second coating satisfies the above range, the tire cord of this embodiment can achieve excellent adhesion to rubber and higher bending rigidity. When the content ratio of the second coating exceeds 0% by mass, the tire cord of this embodiment can achieve good adhesion to rubber. To further improve adhesion to rubber, the content ratio of the second coating may be 0.1% by mass or more, 0.2% by mass or more, or 0.5% by mass or more. When the content ratio of the second coating is 5% by mass or less, the filament bundle and the first coating can be provided in a mass ratio sufficient to obtain high bending rigidity, thereby achieving higher bending rigidity.

[0064] When the second coating is a coating composed of a resorcinol-formaldehyde condensate and a rubber component, the content of the second coating described above refers to the total content of the resorcinol-formaldehyde condensate and the rubber component in the tire cord of this embodiment. Therefore, in the tire cord of this embodiment, the content of the resorcinol-formaldehyde condensate and the rubber component may be, for example, greater than 0% by mass and 5% by mass or less. When the total content of the resorcinol-formaldehyde condensate and the rubber component exceeds 0% by mass, the tire cord of this embodiment can achieve good adhesion to rubber. To further improve adhesion to rubber, the total content of the resorcinol-formaldehyde condensate and the rubber component may be 0.1% by mass or more, 0.2% by mass or more, or 0.5% by mass or more. When the total content of the resorcinol-formaldehyde condensate and the rubber component is 5% by mass or less, the filament bundle and the first coating can be provided in a mass ratio sufficient to obtain high bending rigidity, thereby realizing higher bending rigidity.

[0065] The second coating is formed, for example, by applying a second treatment agent (described later) to at least a portion of the surface of a precursor cord having a first coating formed on at least a portion of the surface of the filament bundle, and then drying the applied agent by heat treatment. The application of the second treatment agent to the surface of the precursor cord can be carried out, for example, by impregnating the precursor cord with the second treatment agent or by applying the second treatment agent to at least a portion of the surface of the precursor cord.

[0066] Examples of the rubber component contained in the second coating include butadiene-styrene copolymer, dicarboxylated butadiene-styrene copolymer, vinylpyridine-butadiene-styrene copolymer, chloroprene rubber, butadiene rubber, chlorosulfonated polyethylene, nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber.

[0067] An example of the tire cord of this embodiment is a tire cord in which the strand is composed of one filament bundle, a first coating, and a second coating, and the filament bundle is untwisted. In this example, the tire cord may be composed of one strand.

[0068] An example of a manufacturing method for the tire cord of this embodiment will be described below. Note that, since the matters described for the tire cord of this embodiment can be applied to the manufacturing method below, duplicated explanations may be omitted. Furthermore, the matters described for the manufacturing method below can be applied to the tire cord of this embodiment.

[0069] An example of a method for manufacturing a tire cord according to the present embodiment includes: (a) bundling a plurality of filaments, each including at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, to prepare at least one filament bundle; (b) forming a first coating so as to cover at least a portion of the surface of the filament bundle; and (c) forming a second coating on the first coating, wherein in the step (b), a first treatment agent containing an epoxy resin and a curing agent is supplied to at least a portion of the surface of the filament bundle, and the epoxy resin is cured to form the first coating; and in the step (c), a second treatment agent containing a resorcinol-formaldehyde condensate and rubber latex is supplied to the precursor cord, in which the first coating has been formed on at least a portion of the surface of the filament bundle, on the first coating, and the second coating is formed by drying.

[0070] First, in the above step (a), a plurality of filaments are bundled together to form a filament bundle.

[0071] In the above (b), a first treatment agent containing an epoxy resin and a curing agent is supplied to at least a portion of the surface of the filament bundle, and the epoxy resin is cured to form a first coating. Examples of epoxy resins and curing agents that can be used in the first treatment agent are the same as those described as examples of the epoxy resin and curing agent used in the first coating. After the first treatment agent is supplied to the surface of the filament bundle, the epoxy resin is cured by, for example, heat treatment to form the first coating. The heat treatment temperature when forming the first coating is, for example, 150°C to 300°C. The heat treatment time when forming the first coating is, for example, 5 seconds to 600 seconds.

[0072] In the above (b), the first treating agent is preferably supplied so that the content of the first coating in the tire cord is 15% by mass or more and 50% by mass or less. For example, when the first coating is made of only a cured epoxy resin, the first treating agent is preferably supplied so that the total mass of the epoxy resin and the curing agent is 15% by mass or more and 50% by mass or less, based on the tire cord.

[0073] In the first treatment agent, the mass ratio of the epoxy resin to the total of the epoxy resin and the curing agent is preferably, for example, 40 mass % or more and 95 mass % or less.

[0074] In the above (c), a second coating is formed on a precursor cord having a first coating formed on at least a portion of the surface of the filament bundle by supplying a second treatment agent containing a resorcinol-formaldehyde condensate and a rubber latex onto the first coating and drying the second treatment agent. Examples of rubber latex that can be used in the second treatment agent include the rubber latexes exemplified as the rubber component contained in the second coating. The heat treatment temperature for drying the second treatment agent when forming the second coating is, for example, 80°C to 300°C. The heat treatment time is, for example, 5 to 120 seconds.

[0075] In the above (c), the second treating agent is preferably supplied so that the content of the second coating in the tire cord is more than 0% by mass and not more than 5% by mass. For example, when the second coating is composed only of a resorcinol-formaldehyde condensate and a rubber latex, the second treating agent is preferably supplied so that the total mass of the solids in the resorcinol-formaldehyde condensate and the rubber latex is more than 0% by mass and not more than 5% by mass, relative to the tire cord.

[0076] The tire cord of this embodiment is used, for example, in a belt-shaped belt member provided along the circumferential direction of the tire in the portion where the tire comes into contact with the road surface, between a member forming the tire's framework (e.g., a carcass) and the surface of the tire that comes into contact with the road surface. For example, Fig. 2 is a cross-sectional view showing an example of a belt member including the tire cord shown in Fig. 1. As shown in Fig. 2, the belt member 20 includes the tire cord 10 and a matrix rubber 21 in which the tire cord 10 is embedded.

[0077] The tire for which the tire cord of the present embodiment is used is not particularly limited, and examples thereof include pneumatic tires such as radial tires and bias tires, and airless tires.

[0078] FIG. 3 shows an example of a tire in which the tire cord of the present embodiment can be used. The tire cord of the present embodiment may be applied to, for example, an airless tire as shown in FIG. 3. FIG. 3 is a perspective view showing an example of an airless tire. FIG. 4 is a cross-sectional view of a shear band provided on the airless tire shown in FIG. 3. The airless tire 100 shown in FIG. 3 includes a radially outer ground-engaging tread 200, a shear band 300, and a connecting web 500. The tread 200 may include elements such as ribs, blocks, lugs, grooves, and sipes as desired to improve tire performance in various conditions. The connecting web 500 is attached to a hub 512 and may have various structures. The connecting web 500 is configured to buckle or deform in the tire footprint and become a rigid structure when in tension and does not support compression or compressive loads. The connecting web 500 may include, for example, a plurality of spokes 510. The shear band 300 is, for example, a ring-shaped structure located radially inward of the tread 200, which functions to transfer loads from the bottom of the tire in contact with the ground to the spokes and hub, creating a top-loader structure. Details of the shear band 300 are shown in FIG. 4 . The shear band 300 includes, for example, a group of reinforcing layers and a group of shear layers. The group of reinforcing layers may have one or more individual reinforcing layers 301. Each reinforcing layer 301 corresponds to the belt member 20 described above and includes, for example, a plurality of tire cords 10 arranged parallel to one another. The group of shear layers may have one or more individual shear layers 302. Each shear layer 302 is, for example, disposed between the reinforcing layers 301. Each shear layer 302 is, for example, a layer of rubber containing cloth or cords made of nylon, PET, etc., or a layer made of rubber alone, and provides the tire with flexibility and stretchability.

[0079] Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples and comparative examples.

[0080] [Manufacturing of Tire Cords] (Examples 1 to 5) A glass fiber (filament bundle) was prepared by bundling 2,000 glass fiber filaments (E-glass composition, average diameter 17 μm). One of these glass fibers was immersed in a first treatment agent whose components are shown in Table 2A or Table 2B below. Thereafter, the fiber was subjected to a heat treatment for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle.

[0081] The surface of the precursor cord was coated with the RFL(A) treatment agent shown in Table 3 below as a second treatment agent, and then dried for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a tire cord was produced in which a second coating was formed on a first coating. The produced tire cord had a cross-sectional structure as shown in Figure 1.

[0082] For the tire cords of Examples 1 to 5, the mass proportion of the glass fiber filaments in the tire cord was determined. The mass of the glass fiber filaments in the tire cord was determined by removing components other than the glass fiber filaments (the first coating and the second coating) from the tire cord by heat treatment. Specifically, the mass (mass before heating) of a tire cord prepared as a test specimen was first measured, and then this test specimen was heated for 15 minutes or more in an electric furnace maintained at 650±20°C. Thereafter, the test specimen was cooled to room temperature, and its mass (mass after heating) was measured and used as the mass of the glass fiber filaments. The mass proportion of the glass fiber filaments in the tire cord, i.e., the "mass proportion of glass fiber filaments" in Table 5, was determined using the following formula: Mass proportion of glass fiber filaments (%) = 100 × b / a a: mass (g) before heating b: mass (g) after heating

[0083] Example 6 A glass fiber (filament bundle) was prepared by bundling 2,000 glass fiber filaments (E-glass composition, average diameter 13 μm). Two of these glass fibers were immersed in a first treatment agent whose components are shown in Table 2A below. Then, a heat treatment was performed for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of the glass fiber filaments in the obtained tire cord were the same as those used in Examples 1 to 5.

[0084] Example 7 A glass fiber (filament bundle) was prepared by bundling 400 glass fiber filaments (M glass composition, average diameter 10 μm). 18 of these glass fibers were immersed in a first treatment agent whose components are shown in Table 2A below. Then, a heat treatment was performed for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of the glass fiber filaments in the obtained tire cord were the same as those in Examples 1 to 5.

[0085] Example 8 A glass fiber (filament bundle) was prepared by bundling 1,200 glass fiber filaments (M glass composition, average diameter 17 μm). Two of these glass fibers were immersed in a first treatment agent whose components are shown in Table 2A below. Then, a heat treatment was performed for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of the glass fiber filaments in the resulting tire cord were the same as those used in Examples 1 to 5.

[0086] Example 9 A carbon fiber (filament bundle) consisting of 12,000 carbon fiber filaments (average diameter: approximately 7 μm) was used. One carbon fiber was immersed in a first treatment agent whose components are shown in Table 2A below. It was then subjected to a heat treatment for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle.

[0087] A second treatment agent having components as shown in Table 3 below was applied to the surface of the precursor cord, and the cord was dried for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a tire cord was produced in which a second coating was formed on the first coating. The produced tire cord had a cross-sectional structure as shown in Figure 1.

[0088] The mass proportion of the carbon fiber filaments in the tire cord was determined using the mass of the carbon fiber filaments used.

[0089] Examples 10 to 12: A carbon fiber (filament bundle) consisting of 12,000 carbon fiber filaments (average diameter: approximately 7 μm) was used. One carbon fiber was immersed in a first treatment agent whose components are shown in Table 2A below. The fiber was then heat-treated for approximately 10 to 20 seconds in a drying oven set at 280°C. In this manner, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of the carbon fiber filaments in the resulting tire cord were the same as those in Example 9.

[0090] Example 13 A carbon fiber (filament bundle) consisting of 12,000 carbon fiber filaments (average diameter approximately 5 μm) was used. One carbon fiber was immersed in a first treatment agent whose components are shown in Table 2A below. The carbon fiber was then heat-treated for approximately 10 to 20 seconds in a drying oven set at 280°C. In this manner, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of carbon fiber filaments in the resulting tire cord were the same as those in Example 9.

[0091] Example 14 A carbon fiber (filament bundle) consisting of 6,000 carbon fiber filaments (average diameter: approximately 7 μm) was used. One carbon fiber was immersed in a first treatment agent whose components are shown in Table 2A below. The carbon fiber was then heat-treated for approximately 10 to 20 seconds in a drying oven set at 280°C. In this manner, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle. The method for forming the second coating and the method for determining the mass proportion of carbon fiber filaments in the resulting tire cord were the same as those in Example 9.

[0092] Example 15 A glass fiber (filament bundle) was prepared by bundling 200 glass fiber filaments (E-glass composition, average diameter 9 μm). Three of these glass fibers were aligned and coated with the RFL (B) treatment agent shown in Table 3 below. This was then dried for 2 minutes in a drying oven set at 200°C. A strand was thus formed. Ten of these strands were aligned and then second-twisted (S-twisted) at a ratio of 2 turns per 25 mm. The surface of the obtained cord was immersed in a first treatment agent whose components are shown in Table 2A. This was then heat-treated for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle.

[0093] Example 16 A glass fiber (filament bundle) was prepared by bundling 2,000 glass fiber filaments (E-glass composition, average diameter 17 μm). Each glass fiber was S-twisted twice per 25 mm. The surface of the obtained cord was immersed in a first treatment agent whose components are shown in Table 2A. The cord was then heat-treated for approximately 10 to 20 seconds in a drying oven set at 280°C. In this way, a precursor cord was produced in which a first coating was formed on the surface of the filament bundle.

[0094] Comparative Example 1 A known steel cord used as a tire cord was used as the tire cord of Comparative Example 1. This steel cord was made by bundling five steel filaments with a diameter of 0.5 mm together and twisting them at a ratio of 60 turns per meter using a Z twist.

[0095] Comparative Example 2 A glass fiber (filament bundle) was prepared by bundling 200 glass fiber filaments (E-glass composition, average diameter 9 μm). Three of these glass fibers were aligned and coated with the RFL (B) treatment agent shown in Table 3 below. This was then dried for 2 minutes in a drying oven set at 200°C. A strand was thus formed. Ten of these strands were aligned and then second-twisted (S-twisted) at a rate of 2 turns per 25 mm. Chemlock 233X (manufactured by Lord Japan Inc.) was applied to the surface of the obtained cord and dried to form a tire cord. In the obtained tire cord, the mass of the solids of RFL (B) was 20.2 mass%, and the mass of the solids of Chemlock 233X was 3.9 mass%.

[0096] (Comparative Example 3) A tire cord was produced in the same manner as in Examples 1 to 5, except that the first coating was not formed and the second coating was produced so as to account for 14.5 mass % of the tire cord. In addition, the mass proportion of the glass fiber filaments in the tire cord was determined in the same manner as in Examples 1 to 5.

[0097] (Comparative Example 4) A tire cord was produced in the same manner as in Examples 1 to 5, except that the second coating was not formed and the mass ratio of the first coating in the tire cord was changed. In addition, the mass ratio of the glass fiber filaments in the tire cord was determined in the same manner as in Examples 1 to 5.

[0098] [Adhesion Evaluation] (1) Equipment Used Press (Shinto Metal Industries, Inc., top-push automatic molding machine (SFA-50 model)) Dedicated upper and lower molds Tensile testing machine (Shimadzu Corporation, Autograph AGS-500A model or AGS-D model) (2) Sample Tire cord to be measured (length 30 mm) (3) Preparation for vulcanization Four rubber pieces (width 10 mm x length 200 mm x thickness 3 mm) were prepared. These rubber pieces were formed from rubber having the composition shown in Table 4. Two rubber pieces were set in each of the two molding grooves of the lower mold. The 10 tire cords to be measured were set along the cord grooves using the mold frame while being pulled to an extent that they did not stretch. The 10 tire cords were set at equal intervals from each other in the length direction of the rubber piece, and were set so that the length direction of the tire cords was aligned with the width direction of the rubber piece. Then, a rubber piece was placed on top of each of the rubber pieces set in the lower mold, and the upper mold was set on top of them. (4) Vulcanization The temperature of the press was adjusted to 150±5°C using a surface thermometer. After preheating the press for 5 minutes, a pressure of 49 kg / cm was applied. 2 The rubber pieces were vulcanized for 20 minutes while being pressed at 100°C. After vulcanization, they were removed from the mold and left to stand at room temperature for 24 hours. Then, they were cut into the shapes shown in Figure 5 (i.e., 200 mm long rubber pieces were cut into 20 mm long pieces) to prepare test pieces. (5) Measurement Using a tensile tester, the maximum tensile load was read from the chart at a pulling rate of 50 mm / min using a dedicated chuck, and the adhesive strength was determined. The adhesive strength measurement was carried out at 23°C.

[0099] The results of the adhesion evaluation of the tire cords of each of the Examples and Comparative Examples are shown in Tables 5 and 6.

[0100] [Method for Measuring Three-Point Bending Elastic Modulus] The method for measuring the three-point bending elastic modulus is as described in the embodiment. That is, the three-point bending elastic modulus was determined by the following method. (1) A test specimen was prepared in which 20 tire cords were embedded inside a matrix rubber having the composition shown in Table 1 above. Here, the test specimen had a rectangular parallelepiped shape with a width (W) of 25 mm, a length of 120 mm, and a height (h) of 4 mm. The 20 tire cords had a length of 110 mm. In the test specimen, the length direction of each tire cord was aligned with the length direction of the test specimen, and the 20 tire cords were arranged at regular intervals across the width direction of the test specimen. However, in the test specimen of this example, the intervals between the tire cords were very narrow, and the 20 tire cords were arranged with almost no gaps between them. (2) Three-point bending measurement was performed on the test specimen at 23°C, with a support distance (Lv) of 30 mm and a bending speed of 5 mm / min, and a bending load-deflection curve was determined. (3) For the bending load-bending deflection curve, the gradient (change in bending load (ΔF) / change in bending deflection (ΔY)) at bending deflection of 1.5 mm to 2.5 mm was determined, and the three-point bending modulus was calculated using the gradient according to the following formula (I).

[0101] Formula (I): Three-point bending elastic modulus (MPa) = (Lv 3 / 4Wh 3 ) × (ΔF / ΔY)

[0102] Specifically, the above test specimen was prepared as follows. Two pieces of rubber (25 mm wide, 120 mm long, and approximately 3 mm high) having the composition shown in Table 1 were prepared, and tire cords were placed between the two rubber pieces so that the length direction of the tire cords was aligned with the length direction of the test specimen and at regular intervals across the width direction of the test specimen. However, as mentioned above, in the test specimen of this example, the intervals between the tire cords were very narrow, and the 20 tire cords were lined up with almost no gaps. This was subjected to a pressure of 49 kg / cm 2 The rubber pieces were vulcanized by heat treatment at a temperature of 160° C. for 20 minutes while being pressed at 100° C. to obtain test pieces.

[0103] In the present examples and comparative examples, the following specific components were used for each component shown in Table 1. Styrene butadiene rubber: JSR1501, manufactured by JSR Corporation Carbon black: Seast S (SRF), manufactured by Tokai Carbon Stearic acid: Camellia stearic acid beads, manufactured by NOF Corporation Sulfur: HK200-5, manufactured by Hosoi Chemical Industry Co., Ltd. Zinc oxide: Zinc oxide, manufactured by Seido Chemical Industry Co., Ltd. 2-(Morpholidithio)benzothiazole: Noccela MDB, manufactured by Ouchi Shinko Chemical Co., Ltd. Naphthenic acid process oil: SNH-22, manufactured by Sankyo Yuka Kogyo Co., Ltd.

[0104] The results of the three-point bending modulus of elasticity of the tire cords of each of the Examples and Comparative Examples are shown in Tables 5 to 8.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] From the results shown in Tables 5 to 8, the tire cords of Examples 1 to 16 had a three-point bending modulus of more than 100 MPa, making it possible to realize a belt member with high bending rigidity. Furthermore, all of the tire cords of Examples 1 to 16 had high adhesive strength. Thus, it was confirmed that the tire cords of Examples 1 to 16 can realize a tire belt member having bending rigidity comparable to or higher than that of the steel cord of Comparative Example 1, and can also realize excellent adhesion to rubber.

[0114] The cord of Comparative Example 2, which is a conventional rubber-reinforcing cord, had sufficient adhesion to rubber but a low three-point bending modulus, making it impossible to achieve sufficient bending rigidity. The cord of Comparative Example 3, which did not have a first coating containing a cured epoxy resin, also had sufficient adhesion to rubber but a low three-point bending modulus, making it impossible to achieve sufficient bending rigidity. The cord of Comparative Example 4, which had a first coating containing a cured epoxy resin but did not have a second coating containing a resorcinol-formaldehyde condensate and a rubber component, had a high three-point bending modulus and was able to achieve high bending rigidity, but its adhesion to rubber was insufficient.

[0115] The present invention can be used for tire reinforcing cords.

Claims

1. A tire cord for reinforcing a tire, the tire cord comprising at least one strand, the strand comprising: at least one filament bundle; a first coating provided so as to cover at least a portion of the surface of the filament bundle; and a second coating provided on the first coating, the filament bundle comprising at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, the first coating comprising a cured epoxy resin, and the second coating comprising a resorcinol-formaldehyde condensate and a rubber component, the tire cord having a three-point bending modulus of 100 MPa or greater as determined by the following three-point bending measurement method. Three-point bending measurement method: (1) Prepare a test specimen in which 20 of the tire cords are embedded inside a matrix rubber having the composition shown in Table 1 below. The test specimen has a rectangular parallelepiped shape with a width (W) of 25 mm, a length of 120 mm, and a height (h) of 4 mm. The 20 tire cords have a length of 110 mm. In the test specimen, the length direction of each tire cord is aligned with the length direction of the test specimen, and the 20 tire cords are arranged at regular intervals in the width direction of the test specimen. (2) At 23°C, a three-point bending measurement is performed on the test specimen with a support distance (Lv) of 30 mm and a bending speed of 5 mm / min, and a bending load-deflection curve is obtained. (3) For the bending load-deflection curve, the gradient (change in bending load (ΔF) / change in bending deflection (ΔY)) at a bending deflection of 1.5 mm to 2.5 mm is obtained, and the three-point bending modulus is obtained using the gradient according to the following formula (I). Formula (I): Three-point bending modulus (MPa) = (Lv 3 / 4Wh 3 ) × (ΔF / ΔY) 2. The tire cord according to claim 1, wherein the content of the first coating in the tire cord is 15% by mass or more and 50% by mass or less.

3. A tire cord according to claim 1, wherein the content of the second coating in the tire cord is greater than 0% by mass and not more than 5% by mass.

4. A tire cord according to claim 1, wherein the filament bundle contains the glass fiber filaments, and the mass ratio of the glass fiber filaments in the tire cord is 50 mass % or more and 80 mass % or less.

5. A tire cord according to claim 1, wherein the filament bundle contains the carbon fiber filaments, and the mass ratio of the carbon fiber filaments in the tire cord is 40 mass % or more and 70 mass % or less.

6. A tire cord according to claim 1, wherein the cured product of the epoxy resin is a reaction product of the epoxy resin and a curing agent, and the mass ratio of the epoxy resin to the total of the epoxy resin and the curing agent is 40 mass % or more and 95 mass % or less.

7. The tire cord according to claim 1, wherein the filament bundle is untwisted.

8. A tire cord according to claim 1, wherein the strand is composed of one of the filament bundles, the first coating, and the second coating, and the filament bundle is untwisted.

9. The tire cord according to claim 8, wherein the tire cord comprises one strand.

10. The tire cord according to claim 1, wherein the tire cord is embedded in a belt member of a tire.

11. A method for producing a tire cord according to any one of claims 1 to 10, comprising: (a) bundling a plurality of filaments, each including at least one selected from the group consisting of glass fiber filaments and carbon fiber filaments, to produce at least one filament bundle; (b) forming a first coating so as to cover at least a portion of the surface of the filament bundle; and (c) forming a second coating on the first coating, wherein in (b), a first treating agent containing an epoxy resin and a curing agent is supplied to at least a portion of the surface of the filament bundle, and the epoxy resin is cured to form the first coating; and in (c), a second treating agent containing a resorcinol-formaldehyde condensate and rubber latex is supplied to the first coating of a precursor cord in which the first coating has been formed on at least a portion of the surface of the filament bundle, and the second coating is formed by drying the second treating agent.

12. The method for producing a tire cord according to claim 11, wherein in (b), the first treatment agent is supplied so that the content of the first coating in the tire cord is 15 mass % or more and 50 mass % or less.

13. The method for producing a tire cord according to claim 11, wherein in (c), the second treatment agent is supplied so that the content of the second coating in the tire cord is greater than 0 mass % and not more than 5 mass %.

14. A method for producing a tire cord as set forth in claim 11, wherein in the first treatment agent, the mass ratio of the epoxy resin to the total of the epoxy resin and the curing agent is 40 mass % or more and 95 mass % or less.

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