Rubber-organic fiber cord composite and tire

Abstract

To provide a rubber-organic fiber cord composite that can suppress degradation of tire performance while using polyamide fibers with low amide density.SOLUTION: A rubber-organic fiber cord composite is made in such a manner that an organic fiber cord is coated with a coating rubber. The organic fiber cord contains polyamide fiber having an amide density of 14.0 or less. The coating rubber has a loss tangent tanδ(24°C) of 0.15 or less that is measured under conditions of temperature 24°C, initial strain 6%, amplitude ±1%, and frequency 52 Hz, and a loss tangent tanδ(60°C) of 0.10 or less that is measured under conditions of temperature 60°C, initial strain 1.5%, amplitude ±1%, and frequency 52 Hz.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber-organic fiber cord composite and a tire. [Background technology]

[0002] Conventionally, a carcass layer containing reinforcing cords is disposed inside a tire to reinforce the strength and rigidity of the tire, and a belt layer containing reinforcing cords is disposed radially outward of the carcass layer. Furthermore, a belt reinforcing layer (also called a "cap layer") containing reinforcing cords may be disposed radially outward of the belt layer to reinforce the belt layer. Among these tire components, organic fiber cords such as polyamide (nylon) fiber cords are widely used as reinforcing cords for the carcass layer and the belt reinforcing layer, and rubber-organic fiber cord composites obtained by coating the organic fiber cords with coating rubber are widely used for the carcass layer and the belt reinforcing layer.

[0003] On the other hand, in recent years, from the viewpoint of reducing the environmental load, there has been a demand for reducing the amount of fossil resources used, such as petroleum and coal. Therefore, with regard to the organic fiber cords, the replacement of cords derived from fossil resources with cords derived from biomass (biological resources) has also been considered, and such replacement must be able to sufficiently maintain tire performance. For example, Patent Document 1 listed below discloses a reinforcing ply having a reinforcing element containing a multifilament yarn made of nylon 4,10, and a pneumatic vehicle tire including the reinforcing ply, and teaches that one of the two monomers of nylon 4,10 is based on renewable raw materials, making it environmentally friendly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-511411 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, polyamide fiber cords are widely used as reinforcing cords for carcass layers and belt reinforcing layers, and polyamide 6,6 (PA66) fiber cords are particularly commonly used. However, polyamide 6,6, the raw material for polyamide 6,6 (PA66) fiber cords, is difficult to synthesize from biomass. In response to this, the present inventors have conducted research and found that although polyamide 4,10 (i.e., nylon 4,10) can be easily synthesized from biomass, it has a lower amide density and fewer hydrogen bonds between amide bonds than polyamide 6,6, resulting in poor thermal properties. As a result, an organic fiber cord using such polyamide 4,10 exhibits reduced physical properties at high temperatures, and when a rubber-organic fiber cord composite including such an organic fiber cord is applied to a tire, tire performance is reduced.

[0006] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber-organic fiber cord composite that can suppress deterioration of tire performance even when using polyamide fiber having a lower amide density than polyamide 6,6 fiber. Another object of the present invention is to provide a tire that suppresses deterioration in tire performance while using polyamide fiber that has a lower amide density than polyamide 6,6 fiber. [Means for solving the problem]

[0007] The rubber-organic fiber cord composite and tire of the present invention that solve the above problems are outlined below.

[0008] [1] A rubber-organic fiber cord composite obtained by coating an organic fiber cord with a coating rubber, the organic fiber cord contains polyamide fibers having an amide density of 14.0 or less, The coating rubber has a loss tangent tanδ(24°C) of 0.15 or less when measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and a loss tangent tanδ(60°C) of 0.10 or less when measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz. The rubber-organic fiber cord composite of the present invention described in [1] above can suppress deterioration of tire performance by applying it to a tire, even though it uses polyamide fiber having an amide density of 14.0 or less.

[0009] [2] The rubber-organic fiber cord composite according to [1], wherein the coating rubber has a loss tangent tanδ (24°C) of 0.12 or less. The rubber-organic fiber cord composite described in [2] above can be used in tires to further suppress the deterioration of tire performance.

[0010] [3] The rubber-organic fiber cord composite according to [1] or [2], wherein the coating rubber has a loss tangent tanδ(60°C) of 0.07 or less. The rubber-organic fiber cord composite described in [3] above can be applied to a tire to further suppress the deterioration of tire performance.

[0011] [4] The rubber-organic fiber cord composite according to any one of [1] to [3], wherein the rubber composition used for the coating rubber contains natural rubber and styrene-butadiene rubber as rubber components, and the content of the natural rubber in 100 parts by mass of the rubber components is 70 parts by mass or more. The rubber-organic fiber cord composite described in [4] above can be applied to a tire to further suppress the deterioration of tire performance.

[0012] [5] The rubber-organic fiber cord composite according to [4], wherein the styrene-butadiene rubber is non-oil-extended styrene-butadiene rubber. When the rubber-organic fiber cord composite described in [5] above is applied to a tire, it is possible to further suppress heat generation inside the tire and further suppress deterioration of tire performance.

[0013] [6] The rubber composition used for the coating rubber contains 30 to 60 parts by mass of carbon black per 100 parts by mass of the rubber component, and the nitrogen adsorption specific surface area (N2SA) of the carbon black is 40 m 2 / g or less. The rubber-organic fiber cord composite described in [6] above can be applied to a tire to further suppress the deterioration of tire performance.

[0014] [7] The rubber-organic fiber cord composite according to any one of [1] to [6], wherein the rubber composition used for the coating rubber does not contain an oil component derived from a polymer. The rubber-organic fiber cord composite described in [7] above can be applied to a tire to further suppress the deterioration of tire performance.

[0015] [8] The rubber-organic fiber cord composite according to any one of [1] to [7], wherein the oil content in the rubber composition used for the coating rubber is 0.2 mass % or less. When the rubber-organic fiber cord composite described in [8] above is applied to a tire, it is possible to further suppress the deterioration of tire performance.

[0016] [9] A tire having a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, At least one carcass layer extending in a toroidal shape across the pair of bead portions; At least one belt layer arranged on the tire radially outer side of the crown portion of the carcass layer; At least one belt reinforcing layer disposed radially outward of the belt layer, A tire, wherein at least one of the carcass layers or at least one of the belt reinforcing layers, or at least one of the carcass layers and at least one of the belt reinforcing layers, is the rubber-organic fiber cord composite according to any one of [1] to [8]. The tire of the present invention described in [9] above uses polyamide fibers having an amide density of 14.0 or less, yet the degradation of tire performance is suppressed.

[0017]

[10] The tire according to [9], wherein at least one of the belt reinforcing layers is the rubber-organic fiber cord composite. In the tire described in

[10] above, biomass-derived polyamide fibers can be easily applied to the belt reinforcing layer, and the environmental load can be easily reduced. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a rubber-organic fiber cord composite that can suppress deterioration of tire performance even when using polyamide fiber that has a lower amide density than polyamide 6,6 fiber. Furthermore, according to the present invention, it is possible to provide a tire in which degradation of tire performance is suppressed even when using polyamide fiber having a lower amide density than polyamide 6,6 fiber. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of one embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The rubber-organic fiber cord composite and tire of the present invention will be described in detail below by way of example based on embodiments thereof.

[0021] <Definition> In this specification, the term "biomass content" refers to the content rate of carbon derived from biomass, and is calculated using the following formula (1): Biomass ratio (%) = number of carbon atoms derived from biomass / total number of carbon atoms × 100 (1) It is calculated from

[0022] In addition, in this specification, the "biomass content rate of the entire cord" refers to the content rate of biomass-derived carbon in the entire cord, and is calculated using the following formula (2): Biomass-derived carbon atoms in the entire code (%) = Number of carbon atoms in the entire code / Total number of carbon atoms in the entire code × 100 (2) It is calculated from

[0023] In this specification, the heat shrinkage rate of the organic fiber cord is measured in accordance with ASTM D885 and ASTM D4974, and is a value measured by heating at 177°C for 2 minutes.

[0024] In this specification, the "amide density" of a polyamide is calculated by the following formula (3): Amide density = number of amide groups in polyamide / number of atoms in the main chain of polyamide × 100 (3) It is calculated from Here, the "number of amide groups in the polyamide" and the "number of atoms in the main chain of the polyamide" are calculated from the "number of amide groups" and the "number of atoms in the main chain" in one repeating unit of the polyamide. For example, the amide density of polyamide 4 and polyamide 4,4 is 20.0, the amide density of polyamide 5,4 is 18.2, the amide density of polyamide 4,6 is 16.7, the amide density of polyamide 5,6 is 15.4, the amide density of polyamide 6 and polyamide 6,6 is 14.3, the amide density of polyamide 4,10 is 12.5, the amide density of polyamide 6,10 is 11.1, the amide density of polyamide 9,T is 10.5, the amide density of polyamide 10,10 is 9.1, and the amide density of polyamide 11 is 8.3.

[0025] In addition, in this specification, "biomass-derived" refers to being derived from biological resources such as plant resources, animal resources, and microbial resources, and is synonymous with "bio-derived."

[0026] The compounds described herein may be derived partially or entirely from fossil resources, biological resources such as plant resources, or recycled resources such as used tires, or may be derived from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0027] <Rubber-organic fiber cord composite> The rubber-organic fiber cord composite of this embodiment comprises an organic fiber cord coated with a coating rubber, i.e., an organic fiber cord and a coating rubber covering the organic fiber cord. The organic fiber cord contains a polyamide fiber having an amide density of 14.0 or less, and the coating rubber has (i) a loss tangent tanδ(24°C) of 0.15 or less, measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and (ii) a loss tangent tanδ(60°C) of 0.10 or less, measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz.

[0028] The polyamide fiber having an amide density of 14.0 or less has a lower amide density and fewer hydrogen bonds between amide bonds than polyamide 6,6 fiber, resulting in poor thermal properties. As a result, the physical properties of the polyamide fiber having an amide density of 14.0 or less deteriorate at high temperatures, and a rubber-organic fiber cord composite having an organic fiber cord containing the polyamide fiber having an amide density of 14.0 or less deteriorates in performance at high temperatures. In contrast, the rubber-organic fiber cord composite of the present embodiment uses a coating rubber having (i) a loss tangent tanδ(24°C) of 0.15 or less when measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and (ii) a loss tangent tanδ(60°C) of 0.10 or less when measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz. When applied to a tire, this coating rubber suppresses heat generation inside the tire during running, prevents the inside of the tire from becoming too hot, and suppresses deterioration in the physical properties of the organic fiber cord containing a polyamide fiber having an amide density of 14.0 or less. As a result, the performance of the rubber-organic fiber cord composite can be maintained. Therefore, even though the rubber-organic fiber cord composite of this embodiment uses polyamide fibers having an amide density of 14.0 or less, by applying it to a tire, it is possible to suppress a decrease in tire performance.

[0029] (coated rubber) The coating rubber constituting the rubber-organic fiber cord composite of this embodiment has (i) a loss tangent tanδ(24°C) of 0.15 or less when measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and (ii) a loss tangent tanδ(60°C) of 0.10 or less when measured under conditions of a temperature of 24°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz. By having the coating rubber (i) have a loss tangent tanδ(24°C) of 0.15 or less when measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and (ii) have a loss tangent tanδ(60°C) of 0.10 or less when measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz, the hysteresis loss of the coating rubber is reduced from around room temperature to around the temperature during running, and when applied to a tire, heat generation inside the tire can be suppressed. Furthermore, by suppressing heat generation inside the tire, the temperature inside the tire can be prevented from rising too high, and deterioration in the physical properties of the organic fiber cord containing polyamide fiber having an amide density of 14.0 or less can be suppressed. As a result, the performance of the rubber-organic fiber cord composite can be maintained.

[0030] The coating rubber (i) preferably has a loss tangent tanδ (24°C) of 0.15 or less, and more preferably 0.12 or less. If the loss tangent tanδ (24°C) of the coating rubber is 0.12 or less, when the rubber-organic fiber cord composite is applied to a tire, heat generation inside the tire at around room temperature is further suppressed, and deterioration in the physical properties of the organic fiber cord containing polyamide fiber having an amide density of 14.0 or less is further suppressed, thereby more reliably maintaining the performance of the rubber-organic fiber cord composite. Therefore, when a rubber-organic fiber cord composite using a coating rubber having a loss tangent tanδ (24°C) of 0.12 or less is applied to a tire, deterioration in tire performance can be further suppressed.

[0031] The coating rubber preferably has (ii) a loss tangent tanδ (60°C) of 0.10 or less and 0.07 or less. When the coating rubber has a loss tangent tanδ (60°C) of 0.07 or less, when the rubber-organic fiber cord composite is applied to a tire, heat generation inside the tire during running is further suppressed, the temperature inside the tire is further suppressed from rising too high, and deterioration in the physical properties of the organic fiber cord containing polyamide fiber having an amide density of 14.0 or less is further suppressed, thereby more reliably maintaining the performance of the rubber-organic fiber cord composite. Therefore, when a rubber-organic fiber cord composite using a coating rubber having a loss tangent tanδ (60°C) of 0.07 or less is applied to a tire, deterioration in tire performance can be further suppressed.

[0032] The coating rubber may be a rubber composition obtained by compounding a rubber component such as natural rubber or synthetic rubber with a filler such as carbon black, a vulcanizing agent such as sulfur, a vulcanization accelerator, etc.

[0033] The rubber component of the rubber composition used for the coating rubber is not particularly limited, and various elastomers can be used. Examples of such elastomers include diene rubbers and their hydrogenated derivatives, such as natural rubber (NR), synthetic isoprene rubber (IR), epoxidized natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR, high cis BR, and low cis BR), nitrile rubber (NBR), hydrogenated NBR, and hydrogenated SBR, ethylene-propylene rubber (EPDM, EPM), maleic acid-modified ethylene-propylene rubber (M-EPM), butyl rubber (IIR), copolymers of isobutylene and aromatic vinyl or diene monomers, acrylic rubber (ACM), and olefinic rubbers, such as ionomers, Br-IIR, Cl-IIR, brominated isobutylene-paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), and hydrin rubber ( Examples of rubbers that can be used include halogen-containing rubbers such as chlorosulfonated polyethylene rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), and maleic acid-modified chlorinated polyethylene rubber (M-CM); silicone rubbers such as methyl vinyl silicone rubber, dimethyl silicone rubber, and methyl phenyl vinyl silicone rubber; sulfur-containing rubbers such as polysulfide rubber; and fluororubbers such as vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, and fluorine-containing phosphazene rubber; and thermoplastic elastomers such as styrene-based elastomers, olefin-based elastomers, ester-based elastomers, urethane-based elastomers, and polyamide-based elastomers.

[0034] In the rubber-organic fiber cord composite of this embodiment, the rubber composition used for the coating rubber preferably contains natural rubber and styrene-butadiene rubber as rubber components, with the natural rubber content being 70 parts by mass or more per 100 parts by mass of the rubber component. The natural rubber content in the rubber composition used for the coating rubber is more preferably 70 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the rubber component. Furthermore, the styrene-butadiene rubber content in the rubber composition used for the coating rubber is preferably 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component. When natural rubber and styrene-butadiene rubber are contained as rubber components and the natural rubber content is 70 parts by mass or more per 100 parts by mass of the rubber component, the hysteresis loss of the coating rubber is further reduced. When the rubber-organic fiber cord composite is applied to a tire, heat generation inside the tire is further suppressed, and high temperatures inside the tire can be more reliably suppressed. Therefore, when a rubber-organic fiber cord composite using such a coating rubber is applied to a tire, it is possible to further suppress deterioration of tire performance. The natural rubber may be modified. In the case of modified natural rubber, the nitrogen content is preferably 0.1 to 0.3% by mass. The modified natural rubber is preferably one in which proteins have been removed by a centrifugation process, enzyme treatment, or urea treatment. The phosphorus content of the modified natural rubber is preferably more than 200 ppm and not more than 900 ppm.

[0035] It is preferable to use non-oil-extended styrene-butadiene rubber as the styrene-butadiene rubber. When the rubber composition contains non-oil-extended styrene-butadiene rubber, the loss tangent tanδ (24°C) of the rubber composition can be further reduced. Therefore, when a rubber-organic fiber cord composite using a coating rubber containing non-oil-extended styrene-butadiene rubber is applied to a tire, heat generation inside the tire can be further suppressed, and deterioration of tire performance can be further suppressed.

[0036] The carbon black used in the coating rubber is not particularly limited, and examples thereof include GPF, FEF, and HAF grade carbon black, etc. These carbon blacks may be used alone or in combination of two or more.

[0037] The nitrogen adsorption specific surface area (N2SA) of the carbon black is 40 m 2 / g or less, and 2 / g or less is more preferable, and 30m 2 It is particularly preferable that the nitrogen adsorption specific surface area (N2SA) of the carbon black is 25 m / g or less. 2 / g or more. The content of the carbon black is preferably 30 to 60 parts by mass, more preferably 40 to 50 parts by mass, per 100 parts by mass of the rubber component. The rubber composition used for the coating rubber contains 30 to 60 parts by mass of carbon black per 100 parts by mass of the rubber component, and the nitrogen adsorption specific surface area (N2SA) of the carbon black is 40 m 2 / g or less, the hysteresis loss of the coating rubber is further reduced, and when the rubber-organic fiber cord composite is applied to a tire, heat generation inside the tire is further suppressed, and the temperature inside the tire can be more reliably prevented from rising. Therefore, when the rubber-organic fiber cord composite using such a coating rubber is applied to a tire, it is possible to further suppress deterioration in tire performance.

[0038] The carbon black may be recycled carbon black. Furthermore, "recycled carbon black" refers to carbon black obtained by recovering raw materials that are waste materials that have been recycled. Examples of waste materials that have been recycled include rubber products (particularly vulcanized rubber products) containing carbon black, such as used rubber and used tires, and waste oil. "Recycled carbon black" differs from carbon black that is produced directly from hydrocarbon raw materials such as petroleum and natural gas, i.e., non-recycled carbon black. Note that "used" here refers not only to carbon black that has been discarded after actual use, but also to carbon black that has been produced but discarded without actually being used.

[0039] In addition to carbon black, sulfur, and a vulcanization accelerator, the rubber composition used for the coating rubber can also contain antioxidants commonly used in rubber products such as tires, zinc oxide (zinc white), stearic acid, etc. The amount of zinc white in the rubber composition is preferably more than 3 parts by mass and less than 5 parts by mass per 100 parts by mass of the rubber component. If the amount of zinc white is 5 parts by mass or more, aggregation may occur, resulting in poor dispersibility, while if it is 3 parts by mass or less, it may have an adverse effect on the vulcanization reaction.

[0040] The rubber composition used for the coating rubber preferably does not contain any polymer-derived oil. Here, "not containing any polymer-derived oil" means that the rubber composition does not contain any oil that is indirectly blended into the rubber composition as a component contained in a polymer such as the rubber component. By reducing the content of polymer-derived oil in the rubber composition used for the coating rubber to zero, the loss tangent tanδ (24°C) of the rubber composition can be further reduced. Therefore, when a rubber-organic fiber cord composite using a rubber composition that does not contain any polymer-derived oil as the coating rubber is applied to a tire, it is possible to further suppress deterioration in tire performance.

[0041] It is more preferable that the oil content in the rubber composition used for the coating rubber is 0.2% by mass or less. By making the oil content in the rubber composition used for the coating rubber 0.2% by mass or less, the loss tangent tanδ (24°C) of the rubber composition can be further reduced. Therefore, by applying a rubber-organic fiber cord composite using a rubber composition having an oil content of 0.2% by mass or less as the coating rubber to a tire, it is possible to further suppress deterioration in tire performance.

[0042] (organic fiber cord) The organic fiber cord constituting the rubber-organic fiber cord composite of this embodiment contains polyamide fibers having an amide density of 14.0 or less, and may be composed solely of the polyamide fibers having an amide density of 14.0 or less, or may further contain other organic fibers.

[0043] The polyamide fibers having an amide density of 14.0 or less have a lower amide density and fewer hydrogen bonds between amide bonds than the widely used polyamide 6,6 (PA66) fibers, resulting in poor thermal properties and reduced physical properties at high temperatures. However, the rubber-organic fiber cord composite of this embodiment reduces the hysteresis loss of the coating rubber from around room temperature to temperatures during driving. When applied to a tire, this reduces heat generation inside the tire and prevents the tire from becoming too hot, thereby maintaining the performance of the rubber-organic fiber cord composite. While there is no particular lower limit for the amide density of the polyamide fiber, the amide density of the polyamide fiber is preferably 10.5 or higher. When the amide density of the polyamide fiber is 10.5 or higher, some hydrogen bonds are formed between the amide bonds, thereby mitigating the deterioration of thermal properties.

[0044] Polyamide fibers with a high bio-based content are easily used as the polyamide fibers with an amide density of 14.0 or less, and such polyamide fibers with a high bio-based content are highly effective in reducing the environmental impact. Therefore, a rubber-organic fiber cord composite using an organic fiber cord containing polyamide fibers with an amide density of 14.0 or less, and a tire using the rubber-organic fiber cord composite, can easily reduce the environmental impact.

[0045] The organic fiber cord preferably has a biomass-derived carbon content (biomass content) of 15% or more throughout the cord. When the biomass content of the entire cord is 15% or more, the effect of reducing the environmental load is significant. From the viewpoint of further reducing the environmental load, the biomass content of the entire organic fiber cord is preferably 20% or more, and may be 100%.

[0046] The organic fiber cord preferably contains fibers with a biomass-derived carbon content (biomass content) of 40% or more. When the organic fiber cord contains fibers with a biomass content of 40% or more, the effect of reducing the environmental impact is enhanced. Examples of fibers (polyamide fibers) with a biomass content of 40% or more include polyamide 11 (PA11) fibers, polyamide 4,10 (PA410) fibers, polyamide 6,10 (PA610) fibers, and polyamide 10,10 (PA1010). Polyamides, which are the raw materials for these polyamide fibers, can be synthesized from biomass-derived components. Here, biomass-derived components refer to components derived from biological resources such as plant resources, animal resources, and microbial resources.

[0047] Polyamide 11 (PA11) is obtained by polymerization of aminoundecanoic acid, which is obtained from plant sources such as castor beans. Polyamide 4,10 (PA410) is obtained by the condensation polymerization reaction of tetramethylenediamine (carbon number 4) and sebacic acid (carbon number 10). Tetramethylenediamine is obtained from plant resources such as sugarcane, and sebacic acid is obtained from plant resources such as castor beans. Polyamide 6,10 (PA610) is obtained by a condensation polymerization reaction between hexamethylenediamine (carbon number 6) and sebacic acid (carbon number 10), and sebacic acid is obtained from plant resources such as castor beans. Polyamide 10,10 (PA1010) is obtained by a condensation polymerization reaction between decamethylenediamine (having 10 carbon atoms) and sebacic acid (having 10 carbon atoms), and decamethylenediamine and sebacic acid are obtained from plant resources such as castor beans. For example, tetramethylenediamine, also known as "putrescine," can be obtained by fermenting sugarcane to produce glutamic acid, biochemically producing ornithine from the glutamic acid, and decarboxylating the resulting ornithine. Sebacic acid can also be obtained by mechanically pressing castor beans to obtain castor oil, methanolysing the castor oil to obtain methyl ricinoleate, and then saponifying the methyl ricinoleate.

[0048] The organic fiber cord preferably contains fibers with a 100% bio-based content (i.e., completely derived from biomass). By containing fibers with a 100% bio-based content, the effect of reducing the environmental load is further enhanced. Examples of fibers with a 100% bio-based content include polyamide 11 (PA11) fibers, polyamide 4,10 (PA410) fibers, and polyamide 10,10 (PA1010) fibers.

[0049] Examples of polyamide fibers having an amide density of 14.0 or less include polyamide 4,10 (PA410) fibers, polyamide 6,10 (PA610) fibers, polyamide 9,T (PA9T) fibers, polyamide 10,10 (PA1010) fibers, and polyamide 11 (PA11) fibers. Among these, polyamide 4,10 (PA410) fibers are preferred. Polyamide 4,10 fibers with a 100% bio-based content can be used, and such 100% bio-based polyamide 4,10 fibers are highly effective in reducing environmental impact. Therefore, tires using organic fiber cords containing polyamide 4,10 fibers facilitate reducing environmental impact.

[0050] The organic fiber cord may contain organic fibers other than polyamide fibers having an amide density of 14.0 or less. Here, the raw material of the organic fibers other than polyamide fibers having an amide density of 14.0 or less is not particularly limited, and may be derived from synthetic products, biological resources such as plant resources, animal resources, or microbial resources, mechanically recycled by crushing, melting, and re-spinning a resin product, or chemically recycled by depolymerizing and repolymerizing a resin product.

[0051] The material of the organic fiber is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethylene furan dicarboxylate (PEF); polyamides such as 6-nylon (registered trademark), 6,6-nylon (registered trademark), 4,6-nylon (registered trademark), and aramid; and celluloses such as rayon and lyocell.

[0052] Examples of the polyethylene terephthalate (PET) include polyethylene terephthalate obtained by mechanically or chemically recycling PET products, clothing, and the like.

[0053] Examples of the polyamide include polyamides derived from biological resources, such as polyamide 4 (PA4), polyamide 4,4 (PA44), polyamide 5,4 (PA54), polyamide 4,6 (PA46), polyamide 5,6 (PA56), polyamide 6 (also referred to as PA6:6-Nylon (registered trademark)), and polyamide 6,6 (also referred to as PA66:6,6-Nylon (registered trademark)).

[0054] The organic fiber cord is preferably a cord obtained by twisting together the fiber having a bio content of 40% or more and aramid fiber. Such an organic fiber cord has rigidity and excellent thermal properties due to the aramid fiber, and also has a significant effect of reducing environmental impact due to the fiber having a bio content of 40% or more.

[0055] The organic fiber cord is also preferably a cord made by twisting together polyamide 4,10 fiber and aramid fiber. Such an organic fiber cord has rigidity and excellent thermal properties due to the aramid fiber, and is also effective in reducing environmental impact due to the polyamide 4,10 fiber, which can be used with a 100% bio-based content.

[0056] The organic fiber cord is also preferably a cord made of two to four fibers twisted together. An organic fiber cord made of two to four fibers twisted together can achieve a lightweight tire while ensuring sufficient rigidity as a tire reinforcing material. From the same viewpoint, a cord made of two fibers twisted together is preferred.

[0057] The organic fiber cord is also preferably a cord made by twisting together two aramid fibers and one polyamide 4,10 fiber. Such an organic fiber cord is rigid and has excellent thermal properties due to the two aramid fibers, and is also highly effective in reducing environmental impact due to the polyamide 4,10 fiber, which can be made 100% bio-based.

[0058] The organic fiber cord is preferably made solely of polyamide fibers having a biomass-derived carbon content (biomass content) of 15% or more. When the organic fiber cord is made solely of polyamide fibers having a biomass content of 15% or more, the effect of reducing the environmental load is enhanced.

[0059] The organic fiber cord may have a single twist structure or a twisted structure (such as a double twist structure). In the case of a single twist structure, for example, raw yarns are pulled together and twisted in one direction to obtain a twisted cord. Here, the number of twists is preferably in the range of 4 to 20 times per 10 cm. If the number of twists in the single twist structure exceeds 20 times per 10 cm, the strength of the twisted cord may decrease, and if it is less than 4 times per 10 cm, the twisted cord may not have sufficient fatigue resistance. Furthermore, in the case of a two-twist structure, for example, a twisted cord can be obtained by first twisting an original yarn, then combining multiple twists and then final twisting them in the opposite direction. Here, the number of first twists is preferably in the range of 10 to 60 times per 10 cm, and the number of final twists is preferably in the range of 10 to 60 times per 10 cm. If the number of first twists exceeds 60 times per 10 cm, the strength of the twisted cord may decrease, and if it is less than 10 times per 10 cm, the twisted cord may not have sufficient fatigue resistance. If the number of final twists exceeds 60 times per 10 cm, the strength of the twisted cord may decrease, and if it is less than 10 times per 10 cm, the twisted cord may not have sufficient fatigue resistance.

[0060] The organic fiber cord preferably has a heat shrinkage rate of 12.0% or less. When the heat shrinkage rate of the organic fiber cord is 12.0% or less, deterioration of physical properties (particularly elastic modulus and strength) at high temperatures can be suppressed. The organic fiber cord more preferably has a heat shrinkage rate of 9.0% or less. When the heat shrinkage rate of the organic fiber cord is 9.0% or less, uniformity is improved, particularly during high-speed running.

[0061] The total fineness of the organic fiber cord is preferably in the range of 1000 to 6000 dtex. If the total fineness of the organic fiber cord is less than 1000 dtex, sufficient strength as a tire reinforcement cord may not be obtained, and if it exceeds 6000 dtex, the treat becomes thick, and the tire becomes heavy.

[0062] The breaking strength of the organic fiber cord is preferably 6.0 cN / dtex or more. The breaking strength of the organic fiber cord is also preferably 180 N or more. Here, the breaking strength is measured at room temperature (23°C) in accordance with ASTM D855M. When the breaking strength of the organic fiber cord is 6.0 cN / dtex or more or 180 N or more, a sufficient reinforcing effect can be obtained.

[0063] The elongation at break (elongation at break) of the organic fiber cord is preferably 8.0% or more. Here, the elongation at break is measured at room temperature (23°C) in accordance with ASTM D855M. When the elongation at break of the organic fiber cord is 8.0% or more, a sufficient reinforcing effect can be obtained.

[0064] The moisture content of the organic fiber cord is preferably 3.0% or less, as measured in accordance with JIS L 1013. If the moisture content of the organic fiber cord exceeds 3.0%, the physical properties are reduced and a sufficient reinforcing effect cannot be obtained.

[0065] (Adhesive composition) The organic fiber cord is preferably treated with an adhesive composition.

[0066] Examples of the adhesive composition include an adhesive composition containing a thermoplastic polymer (A) having at least one crosslinkable functional group as a pendant group and substantially no addition-reactive carbon-carbon double bonds in its main chain structure, a heat-reactive aqueous urethane resin (B), and an epoxy compound (C), and optionally further containing a rubber latex (D). Treating the organic fiber cord with such an adhesive composition can improve the adhesion between the organic fiber cord and an elastomer (coating rubber) at high temperatures.

[0067] Conventionally, adhesive treatment of organic fiber cords has been performed using a two-bath process, in which an epoxy or isocyanate is applied to the cord surface, followed by a treatment with a resin (hereinafter referred to as RFL resin) composed of a mixture of resorcinol, formaldehyde, and latex. However, this method can result in the resin used in the first bath becoming very hard, increasing strain input to the organic fiber cord and reducing cord fatigue resistance. Furthermore, while such RFL resins can exhibit sufficient cord-to-elastomer adhesion at room temperature, they can exhibit a significant decrease in adhesion at temperatures above 130°C. In contrast, a one-bath mixture (adhesive composition) containing a thermoplastic polymer (A) having at least one crosslinkable functional group as a pendant group and substantially free of addition-reactive carbon-carbon double bonds in its main chain structure, a thermally reactive aqueous urethane resin (B), and an epoxy compound (C) can be used to ensure sufficient adhesion to the elastomer (coating rubber) without curing the organic fiber cord, even at temperatures above 180°C.

[0068] The main chain of the thermoplastic polymer (A) mainly has a linear structure, and the main chain is preferably, for example, an ethylenic addition polymer such as an acrylic polymer, a vinyl acetate polymer, or a vinyl acetate-ethylene polymer; a urethane high molecular weight polymer; etc. However, the thermoplastic polymer (A) is not limited to the above-mentioned ethylenic addition polymer and urethane high molecular weight polymer, as long as it has the function of suppressing resin fluidity at high temperatures and ensuring the breaking strength of the resin by crosslinking the functional groups of the pendant groups.

[0069] The functional group of the pendant group of the thermoplastic polymer (A) is preferably an oxazolidine group, a bismaleimide group, a (blocked) isocyanate group, an aziridine group, a carbodiimide group, a hydrazino group, an epoxy group, an epithio group, or the like.

[0070] In addition, for the above-mentioned thermoplastic polymer (A), heat-reactive aqueous urethane resin (B), epoxy compound (C), and rubber latex (D), those described in Japanese Patent Application No. 2023-040157 and those described in Japanese Patent Application No. 2023-030762 can be used.

[0071] In the adhesive treatment of the organic fiber cord, it is preferable to use a three-type mixed liquid (adhesive composition) of the thermoplastic polymer (A), the heat-reactive aqueous urethane resin (B), and the epoxy compound (C) as a one-bath treatment liquid, and to use a liquid of a conventional RFL resin as a two-bath treatment liquid. Also, in the adhesive treatment, it is possible to treat with only one bath using a mixed liquid (adhesive composition) of the thermoplastic polymer (A), the heat-reactive aqueous urethane resin (B), the epoxy compound (C), and the rubber latex (D).

[0072] In the adhesive composition, the proportion (dry mass ratio) of the thermoplastic polymer (A) is preferably 2 to 75%, the proportion (dry mass ratio) of the thermally reactive aqueous urethane resin (B) is preferably 15 to 87%, the proportion (dry mass ratio) of the epoxy compound (C) is preferably 11 to 70%, and the proportion (dry mass ratio) of the rubber latex (D) is preferably 20% or less.

[0073] On the other hand, from the viewpoint of environmental protection, it is preferable to use a dip treatment liquid that does not contain resorcinol or formalin as the adhesive composition for the reinforcing cord. Examples of such dip treatment liquids include a composition containing (a) a rubber latex having an unsaturated diene and (b) one or more compounds selected from a compound having a polyether skeleton structure and an amine functional group, a compound having an acrylamide structure, a polypeptide, a polylysine, and a carbodiimide. Examples of such dip treatment liquids include a composition containing, in addition to the rubber latex (a) having an unsaturated diene and the compound (b), one or more compounds selected from (c) an aqueous compound having a (thermally dissociable blocked) isocyanate group, a polyphenol (d), and a polyvalent metal salt (e).

[0074] Other examples of the dip treatment liquid that does not contain resorcinol or formalin include a composition containing polyphenols (I) and aldehydes (II). In addition to the polyphenols (I) and aldehydes (II), such a composition may further contain at least one of an isocyanate compound (III) and a rubber latex (IV).

[0075] The adhesive composition for treating (coating) the organic fiber cord with an adhesive contains polyphenols (I) and aldehydes (II), so that good adhesive properties can be exhibited even when resorcinol is not used in consideration of the environmental impact.

[0076] -Polyphenols (I)- The adhesive composition contains polyphenols (I) as a resin component, thereby improving adhesion to organic fiber cords. The polyphenols (I) are typically water-soluble polyphenols, and are not particularly limited as long as they are polyphenols other than resorcinol (resorcinol). The number of aromatic rings or hydroxyl groups in the polyphenols (I) can be appropriately selected.

[0077] From the viewpoint of realizing better adhesive properties, the polyphenols (I) preferably have two or more hydroxyl groups, and more preferably three or more hydroxyl groups. When the polyphenols have three or more hydroxyl groups, the polyphenol or polyphenol condensate is soluble in the adhesive composition (dip treatment liquid) containing water. This allows the polyphenols to be uniformly distributed in the adhesive composition, thereby realizing better adhesive properties. Furthermore, when the polyphenols (I) are polyphenols containing multiple (two or more) aromatic rings, each of the aromatic rings has two or three hydroxyl groups at the ortho, meta, or para positions.

[0078] As the polyphenols (I), for example, those described as polyphenol compounds in International Publication No. 2022 / 130879 can be used. These polyphenols (I) may be used alone or in combination of two or more.

[0079] -Aldehydes (II)- The adhesive composition contains aldehydes (II) as a resin component in addition to the polyphenols (I), thereby achieving high adhesiveness together with the polyphenols (I). Here, the aldehydes (II) are not particularly limited and can be appropriately selected depending on the required performance. In this specification, the aldehydes (II) also include derivatives of aldehydes that are generated from aldehydes.

[0080] Examples of the aldehydes (II) include monoaldehydes such as formaldehyde, acetaldehyde, butylaldehyde, acrolein, propionaldehyde, chloral, butylaldehyde, caproaldehyde, and allylaldehyde, and aliphatic dialdehydes such as glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, and adipaldehyde, aldehydes having an aromatic ring, and dialdehyde starch. These aldehydes (II) may be used singly or in combination of two or more.

[0081] The aldehydes (II) are preferably aldehydes having an aromatic ring or contain aldehydes having an aromatic ring, because this allows for better adhesiveness to be obtained. Furthermore, the aldehydes (II) preferably do not contain formaldehyde. Here, "does not contain formaldehyde" means, for example, that the formaldehyde content of the total mass of the aldehydes is less than 0.5 mass%.

[0082] In the adhesive composition, polyphenols (I) and aldehydes (II) are in a condensed state, and the mass ratio of the polyphenols to the aldehydes having an aromatic ring (content of aldehydes having an aromatic ring / content of polyphenols) is preferably 0.1 or more and 3 or less. This is because the hardness and adhesive properties of the resin, which is the product of the condensation reaction between the polyphenols and the aldehydes having an aromatic ring, become more suitable. From the same viewpoint, the mass ratio of the polyphenols to the aldehydes having an aromatic ring (content of aldehydes having an aromatic ring / content of polyphenols) in the adhesive composition is more preferably 0.25 or more and more preferably 2.5 or less. The above mass ratio is the mass of the dried product (solid content ratio).

[0083] The total content of the polyphenols (I) and the aldehydes (II) in the adhesive composition is preferably 3 to 30% by mass, because this ensures better adhesion without impairing workability, etc. From the same viewpoint, the total content of the polyphenols (I) and the aldehydes (II) in the adhesive composition is more preferably 5% by mass or more and more preferably 25% by mass or less. The total content is the mass of the dry matter (solid content ratio).

[0084] -Isocyanate compound (III)- The adhesive composition preferably further contains an isocyanate compound (III) in addition to the polyphenols (I) and aldehydes (II), which can further enhance the adhesiveness of the adhesive composition due to a synergistic effect with the polyphenols (I) and aldehydes (II).

[0085] Here, the isocyanate compound (III) is a compound that has the effect of promoting adhesion to a resin material (for example, a phenol / aldehyde resin obtained by condensing a polyphenol (I) and an aldehyde (II)) that is the adherend of the adhesive composition, and is a compound that has an isocyanate group as a polar functional group. These isocyanate compounds (III) may be used alone or in combination of two or more.

[0086] The isocyanate compound (III) is not particularly limited, but from the viewpoint of further improving adhesion, it preferably contains a (blocked) isocyanate group-containing aromatic compound. When the adhesive composition contains a (blocked) isocyanate group-containing aromatic compound, the (blocked) isocyanate group-containing aromatic compound is distributed in the vicinity of the interface between the organic fiber cord and the adhesive composition, resulting in a further adhesion-promoting effect. This effect can further improve the adhesion of the adhesive composition to the organic fiber cord.

[0087] As the (blocked) isocyanate group-containing aromatic compound, those described in Japanese Patent Application No. 2023-040157 and those described in Japanese Patent Application No. 2023-030762 can be used.

[0088] The content of the isocyanate compound (III) in the adhesive composition is not particularly limited, but is preferably 5 to 65% by mass from the viewpoint of more reliably ensuring excellent adhesiveness. From the same viewpoint, the content of the isocyanate compound (III) in the adhesive composition is more preferably 10% by mass or more and more preferably 45% by mass or less. The above content is the mass of the dry matter (solid content ratio).

[0089] -Rubber latex (IV)- The adhesive composition may further contain substantially a rubber latex (IV) in addition to the polyphenols (I), aldehydes (II), and isocyanate compound (III), thereby further enhancing the adhesiveness of the adhesive composition to rubber members.

[0090] Here, the rubber latex (IV) is not particularly limited, and examples thereof include natural rubber (NR), as well as synthetic rubbers such as polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), and vinylpyridine-styrene-butadiene copolymer rubber (Vp). These rubber latexes (IV) may be used alone or in combination of two or more.

[0091] When preparing the adhesive composition containing the rubber latex (IV), it is preferable to mix the rubber latex (IV) with the phenols (I) and the aldehydes (II) before compounding the isocyanate compound (III).

[0092] The content of the rubber latex (IV) in the adhesive composition is preferably 20% by mass or more, more preferably 25% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less.

[0093] The method for producing the adhesive composition is not particularly limited, and examples thereof include a method of mixing raw materials such as polyphenols (I), aldehydes (II), and rubber latex (IV) and aging the mixture, or a method of mixing polyphenols (I) and aldehydes (II) and aging the mixture, and then adding rubber latex (IV) and aging the mixture. When the raw materials contain an isocyanate compound (III), the method for producing the adhesive composition may also include a method of adding rubber latex (IV), aging the mixture, and then adding the isocyanate compound (III).

[0094] (Uses of rubber-organic fiber cord composites) The rubber-organic fiber cord composite of this embodiment can be used not only for tires but also for conveyor belts, hoses, and the like.

[0095] <Tires> The tire of this embodiment has a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, and is equipped with at least one carcass layer extending toroidally across the pair of bead portions, at least one belt layer arranged radially outward of the crown portion of the carcass layer, and at least one belt reinforcing layer arranged radially outward of the belt layer. The tire of this embodiment is characterized in that at least one of the carcass layers or at least one of the belt reinforcing layers, or at least one of the carcass layers and at least one of the belt reinforcing layers, is the rubber-organic fiber cord composite of this embodiment described above. The tire of this embodiment includes the above-described rubber-organic fiber cord composite of this embodiment as a carcass layer and / or a belt reinforcing layer, and therefore, even though polyamide fiber having an amide density of 14.0 or less is used, degradation of tire performance is suppressed.

[0096] (Carcass layer and belt reinforcing layer) In the tire of this embodiment, at least one of the carcass layers or at least one of the belt reinforcing layers, or at least one of the carcass layers and at least one of the belt reinforcing layers is the rubber-organic fiber cord composite of this embodiment described above. When at least one of the carcass layers or at least one of the belt reinforcing layers is the rubber-organic fiber cord composite of the present embodiment, other carcass layers and / or belt reinforcing layers can be made of other rubber-cord composites. The reinforcing cords of such other rubber-cord composites can be cords containing any organic fiber, such as polyamide fiber cords or polyester fiber cords. Furthermore, the coating rubber of such other rubber-cord composites can be a rubber composition containing a rubber component such as natural rubber or synthetic rubber, a filler such as carbon black, an antioxidant, a vulcanizing agent such as sulfur, a vulcanization accelerator, and the like.

[0097] In the tire of the present embodiment, at least one of the belt reinforcing layers is preferably the rubber-organic fiber cord composite. In a tire in which at least one of the belt reinforcing layers contains the polyamide fiber having an amide density of 14.0 or less, it becomes easy to apply biomass-derived polyamide fiber to the belt reinforcing layer, and it becomes easy to reduce the environmental load.

[0098] In the carcass layer, the end count of the organic fiber cords is preferably 20 / 50 mm to 70 / 50 mm, and more preferably 50 / 50 mm to 70 / 50 mm. By setting the end count of the organic fiber cords in the carcass layer to 20 / 50 mm or more, the strength of the carcass layer can be improved, and by setting the end count of the organic fiber cords in the carcass layer to 70 / 50 mm or less, an excessive increase in tire weight can be avoided.

[0099] In the carcass layer, the cord diameter of the organic fiber cord is preferably 0.4 mm to 1.2 mm, and more preferably 0.5 mm to 1.0 mm. By making the cord diameter of the organic fiber cord in the carcass layer 0.4 mm or more, the strength of the carcass layer can be improved, and by making the cord diameter of the organic fiber cord in the carcass layer 1.2 mm or less, an excessive increase in tire weight can be avoided.

[0100] In the belt reinforcing layer, the end count of the organic fiber cords is preferably 20 / 50 mm to 70 / 50 mm, and more preferably 30 / 50 mm to 60 / 50 mm. By setting the end count of the organic fiber cords in the belt reinforcing layer to 20 / 50 mm or more, the strength of the belt reinforcing layer can be improved, and by setting the end count of the organic fiber cords in the belt reinforcing layer to 70 / 50 mm or less, an excessive increase in tire weight can be avoided.

[0101] In the belt reinforcing layer, the cord diameter of the organic fiber cord is preferably 0.4 mm to 1.2 mm, and more preferably 0.5 mm to 1.0 mm. By making the cord diameter of the organic fiber cord in the belt reinforcing layer 0.4 mm or more, the strength of the belt reinforcing layer can be improved, and by making the cord diameter of the organic fiber cord in the belt reinforcing layer 1.2 mm or less, an excessive increase in tire weight can be avoided.

[0102] (Belt layer) The tire of this embodiment includes a belt layer on the radially outer side of the crown portion of the carcass layer. The number of belt layers is not particularly limited and may be one, two, or three or more. The belt layer is usually formed by coating reinforcing cords that extend at an angle (for example, at an angle of 15 to 40°) with a coating rubber with respect to the tire equatorial plane, and preferably by coating steel cords with a coating rubber. Also, usually, two or more belt layers are laminated such that the reinforcing cords constituting the belt layers cross each other with the tire equatorial plane in between, and are arranged on the radially outer side of the crown portion of the carcass layer.

[0103] -Coated rubber- As the coating rubber of the belt layer, a rubber composition can be used in which a rubber component such as natural rubber or synthetic rubber is compounded with a filler such as carbon black, an antioxidant, an adhesion promoter such as a cobalt compound containing a cobalt salt, a vulcanizing agent such as sulfur, a vulcanization accelerator, etc.

[0104] The rubber component used for the coating rubber of the belt layer is preferably natural rubber (NR) or synthetic isoprene rubber (IR). The natural rubber may be modified. In the case of modified natural rubber, for example, the nitrogen content is preferably 0.1 to 0.3 mass%. Furthermore, the modified natural rubber is preferably one from which proteins have been removed by a centrifugation process, enzyme treatment, or urea treatment. Furthermore, the phosphorus content of the modified natural rubber is preferably more than 200 ppm and not more than 900 ppm.

[0105] The carbon black used in the coating rubber of the belt layer is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination. The carbon black content is preferably 40 to 80 parts by mass, more preferably 50 to 70 parts by mass, per 100 parts by mass of the rubber component. The carbon black may also be recycled carbon black. Here, "recycled carbon black" refers to carbon black recovered from recycled waste raw materials. Examples of recycled waste include rubber products (especially vulcanized rubber products) containing carbon black, such as used rubber and used tires, and waste oil. "Recycled carbon black" differs from carbon black produced directly from hydrocarbon raw materials such as petroleum and natural gas, i.e., non-recycled carbon black. Note that "used" here refers not only to carbon black that is discarded after actual use, but also to carbon black that is produced but discarded without actually being used.

[0106] -Reinforcement cord- The reinforcing cords used in the belt layer are not particularly limited, but are preferably steel cords. The structure of the steel cord is also not particularly limited. However, from the viewpoint of effectively achieving both improved tire durability and reduced rolling resistance, the steel cord may have a 1×N structure (N is an integer of 2 or more) in which N filaments are twisted together, an M+N structure in which N sheath filaments (N is an integer greater than 1) are twisted spirally around M core filaments (M is an integer of 1 or more) (the core filaments may be twisted or may be bundled without twisting), or a multi-twist structure in which multiple 1×N or M+N structures are twisted together. Furthermore, the cord is preferably a monofilament that is pulled parallel to one another without being twisted together. In addition, in tires, steel cords can be used, for example, as belt cords in belt layers (usually arranged in the tread portion), as well as belt reinforcing layer cords in belt reinforcing layers; carcass cords; reinforcing cords in wire chafers (usually arranged on the outer side of the folded-up portion of the carcass in the tire width direction); bead cords in bead cores (usually arranged in the bead portion); etc.

[0107] The filaments constituting the above-mentioned steel cord have a diameter of X (mm) and a tensile strength of Y (MPa) that satisfies the following formula: 4000-2000X≦Y≦4500-2000X It is preferable that the following formula be satisfied. By using a filament that satisfies the above formula, the strength of the steel cord can be improved, and the cut resistance of the tire can be improved. Here, the tensile strength of the filament is determined in accordance with the provisions of ISO 17832:2009.

[0108] From the viewpoint of fatigue resistance, the hardness of the surface layer of the filament constituting the above-mentioned steel cord is preferably 90 to 110%, and particularly preferably 100%, of the hardness of the inner layer. The hardness can be measured, for example, by Vickers hardness. The surface layer of the filament refers to the layer extending from the outermost surface to a depth of 0.01 mm, and the inner layer refers to the layer extending further inside. The hardness can be measured in a region 0.005 mm deep from the outermost surface for the surface layer, and in a region 0.04 mm deep for the inner layer.

[0109] The steel filaments constituting the above-mentioned steel cord may be steel filaments derived from recycled iron.

[0110] The raw material of the recycled iron is not particularly limited, and examples thereof include scrap iron, steel cord extracted from tires, etc. From the viewpoint of reducing CO2 emissions, the recycled iron is preferably recycled iron obtained by an electric furnace (electric furnace steelmaking method).

[0111] The steel filament derived from recycled iron preferably has an N (nitrogen) content of 60 to 200 ppm by mass, preferably 60 to 89 ppm by mass, a C (carbon) content of 0.7 to 1.0% by mass, a Cu (copper) content of 0.01 to 0.4% by mass, and a Cr (chromium) content of 0.05 to 0.3% by mass. Such steel filaments can be produced using typical recycled iron as a raw material, with an N (nitrogen) content of 60 to 200 ppm by mass, a C (carbon) content of 0.7 to 1.0% by mass, a Cu (copper) content of 0.01 to 0.4% by mass, and a Cr (chromium) content of 0.05 to 0.3% by mass. Such steel filaments do not require advanced refining during production, resulting in a simple manufacturing process. Furthermore, such steel filaments are preferable from an environmental perspective, as they can reduce energy consumption and CO2 emissions during production.

[0112] The steel filaments derived from recycled iron preferably contain iron as the main component and have an Fe (iron) element content of 98 mass % or more.

[0113] (One embodiment) Next, an embodiment of the tire of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of one embodiment of a tire of the present invention.

[0114] The tire 100 shown in FIG. 1 has a pair of bead portions 10, a pair of sidewall portions 20, and a tread portion 30 connected to both sidewall portions 20, and is equipped with a carcass layer 50 extending in a toroidal shape between bead cores 40 embedded in the pair of bead portions 10, two belt layers 60A, 60B arranged radially outward of the crown portion of the carcass layer 50, a belt reinforcing layer (also called a "cap layer") 70A arranged radially outward of the belt layers 60A, 60B so as to cover the entire belt layers 60A, 60B, and a pair of belt reinforcing layers (also called "layer layers") 70B arranged so as to cover only both end portions of the belt reinforcing layer 70A. In the tire 100 shown in FIG. 1, at least one of the carcass layer 50 or the belt reinforcing layers 70A, 70B, or at least one of the carcass layer 50 and the belt reinforcing layers 70A, 70B, is the rubber-organic fiber cord composite of this embodiment described above.

[0115] In the tire 100 shown in Fig. 1, the carcass layer 50 is one layer, but the tire of the present invention may have two or more carcass layers. Furthermore, in the tire 100 shown in Fig. 1, the carcass layer 50 is composed of a main body portion extending in a toroidal shape between a pair of bead cores 40 each embedded in the bead portion 10, and a folded-up portion wound up radially outward from the inner side toward the outer side in the tire width direction around each bead core 40, but the shape and structure of the carcass layer 50 in the tire of the present invention are not limited to this. Here, the carcass layer 50 is preferably formed by coating a plurality of organic fiber cords that extend in a direction substantially perpendicular to the tire circumferential direction (for example, extending at an angle of 70 to 90°) with a coating rubber; that is, the carcass layer 50 is preferably a radial carcass.

[0116] 1 has two belt layers 60A, 60B, but the tire of the present invention may have one or three or more belt layers. In the tire 100 shown in Fig. 1, each of the belt layers 60A, 60B is usually formed by coating reinforcing cords that extend at an angle inclined with respect to the tire equatorial plane (for example, at an angle of 15 to 40°) with a coating rubber, and preferably by coating steel cords with a coating rubber, and further, the two belt layers 60A, 60B are laminated such that the reinforcing cords constituting the belt layers 60A, 60B intersect with each other with the tire equatorial plane in between.

[0117] In the tire 100 shown in Fig. 1, the belt reinforcing layers 70A, 70B are formed by coating reinforcing cords arranged substantially parallel to the tire circumferential direction (for example, at an angle of 0 to 5 degrees relative to the tire circumferential direction) with a coating rubber. The belt reinforcing layers 70A, 70B are formed by continuously spirally winding narrow strips, prepared by coating organic fiber cords with a coating rubber, in the tire circumferential direction. In this case, since there are no joints in the tire circumferential direction, the tire has good uniformity, and since there are no joints, strain concentration in the joints can also be prevented. 1 includes a belt reinforcing layer 70A and a belt reinforcing layer 70B, but a tire in which either the belt reinforcing layer 70A or the belt reinforcing layer 70B is omitted is also an embodiment of the tire of the present invention. In addition, in the tire 100 shown in FIG. 1, the belt reinforcing layer (cap layer) 70A and the belt reinforcing layer (layer layer) 70B each have one layer, but may have two or more layers.

[0118] <Tire manufacturing method> The tire of this embodiment may be obtained by molding an unvulcanized rubber composition or an unvulcanized treat (rubber-organic fiber cord composite) or the like and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization process or the like instead of the unvulcanized rubber composition and then further vulcanizing it. The components of the tire of the present embodiment other than the carcass layer and the belt reinforcing layer are not particularly limited, and known components can be used. Furthermore, the tire of this embodiment is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. [Example]

[0119] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0120] (Comparative Example 1) Two 1400 dtex polyamide 6,6 (PA66) fibers (amide density 14.3) were first twisted, then paralleled and second twisted to produce a twisted cord (cord structure: 1400 / / 2 / 2). The first twist was 22 times per 10 cm, and the second twist was 22 times per 10 cm.

[0121] Example 1 Two 1400 dtex polyamide 4,10 (PA410) fibers (amide density 12.5) were first twisted, then paralleled and second twisted to produce a twisted cord (cord structure: 1400 / / 2 / 2). The first twist was 22 times per 10 cm, and the second twist was 22 times per 10 cm.

[0122] (1) Measurement of the thermal shrinkage rate of the cord According to ASTM D885 and ASTM D4974, the cord was heated at 177° C. for 2 minutes to measure the heat shrinkage of the cord. The results are shown in Table 1.

[0123] (2) Evaluation of cord properties The cord obtained as described above was subjected to a tensile test in accordance with JIS L 1013 "Testing methods for chemical fiber filament yarns," and the load (N)-elongation (%) curve of the cord was measured. The strength (N) and elongation (%) at break at 100°C of Comparative Example 1 were set at 100, and the results were expressed as an index. The results are shown in Table 1.

[0124] [Table 1]

[0125] (Example 2 and Comparative Example 2) Rubber compositions were produced using a conventional Banbury mixer according to the compounding recipes shown in Table 2. The loss tangent tanδ (24°C) and loss tangent tanδ (60°C) of the resulting rubber compositions were measured by the following methods. The results are shown in Table 2.

[0126] (3) Measurement of loss tangent tanδ of rubber composition The rubber composition was vulcanized at 145°C for 33 minutes to obtain vulcanized rubber test pieces. Using a viscoelasticity measuring device (manufactured by Rheometrics), the loss tangent tanδ(24°C) of the obtained vulcanized rubber test pieces was measured under the conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and the loss tangent tanδ(60°C) was measured under the conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz.

[0127] [Table 2]

[0128] *1 NR: Natural rubber, TSR#20 *2 SBR(1): Styrene-butadiene rubber, solution polymerized SBR, non-oil extended (ENEOS Material 1500) *3 SBR(2): Styrene-butadiene rubber, emulsion polymerized SBR, 27.3% oil extended (ENEOS Material 1778) *4 Carbon black (1): GPF-grade carbon black, N2SA (nitrogen adsorption specific surface area) 28m 2 / g, DBP absorption 89ml / 100g *5 Carbon black (2): HAF grade carbon black, N2SA (nitrogen adsorption specific surface area) 71m 2 / g, DBP absorption 103ml / 100g *6 Zinc oxide: 3 types of zinc oxide manufactured by Hakusui Tech Co., Ltd. *7 Anti-aging agent: Non-Flex RD, manufactured by Seiko Chemical Co., Ltd. *8 Sulfur: Tanaka Ai Co., Ltd., SULFUR (5% OIL-TREATED) *9 Vulcanization accelerator: SANCELER NS-G, SANCELER DM-TG

[0129] A comparison between Comparative Example 1 and Example 1 in Table 1 reveals that the cord made of PA410 fiber exhibits a greater decrease in strength at break at high temperatures than the cord made of PA66 fiber.

[0130] In contrast, according to the present invention, as shown in Example 2 in Table 2, a coating rubber is applied in which the loss tangent tanδ(24°C) measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz is 0.15 or less, and the loss tangent tanδ(60°C) measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz is 0.10 or less. This prevents the inside of the tire from becoming too hot during running, and suppresses deterioration in the physical properties of the organic fiber cord containing polyamide fiber with an amide density of 14.0 or less, thereby making it possible to maintain tire performance. [Industrial Applicability]

[0131] The rubber-organic fiber cord composite of the present invention can be used not only for tires but also for conveyor belts, hoses, etc.

[0132] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to the achievement of goals such as "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete action against climate change." [Explanation of symbols]

[0133] 100: Tire 10: Bead section 20: Sidewall 30: Tread section 40:Bead core 50: Carcass layer 60A, 60B: belt layer, 70A: Belt reinforcement layer (cap layer) 70B: Belt reinforcement layer (layer)

Claims

1. A rubber-organic fiber cord composite obtained by coating an organic fiber cord with a coating rubber, the organic fiber cord contains polyamide fibers having an amide density of 14.0 or less, The coating rubber has a loss tangent tanδ(24°C) of 0.15 or less when measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, and a loss tangent tanδ(60°C) of 0.10 or less when measured under conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz.

2. 2. The rubber-organic fiber cord composite according to claim 1, wherein the coating rubber has a loss tangent tan δ (24° C.) of 0.12 or less.

3. 2. The rubber-organic fiber cord composite according to claim 1, wherein the coating rubber has a loss tangent tan δ (60° C.) of 0.07 or less.

4. 2. The rubber-organic fiber cord composite according to claim 1, wherein the rubber composition used for the coating rubber contains natural rubber and styrene-butadiene rubber as rubber components, and the amount of the natural rubber per 100 parts by mass of the rubber component is 70 parts by mass or more.

5. 5. The rubber-organic fiber cord composite according to claim 4, wherein the styrene-butadiene rubber is a non-oil-extended styrene-butadiene rubber.

6. The rubber composition used for the coating rubber contains 30 to 60 parts by mass of carbon black per 100 parts by mass of the rubber component, and the nitrogen adsorption specific surface area (N 2 SA) is 40m 2 2. The rubber-organic fiber cord composite according to claim 1, wherein the elastic modulus is 1 / g or less.

7. 2. The rubber-organic fiber cord composite according to claim 1, wherein the rubber composition used for the coating rubber does not contain an oil component derived from a polymer.

8. 2. The rubber-organic fiber cord composite according to claim 1, wherein the oil content in the rubber composition used for the coating rubber is 0.2% by mass or less.

9. a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, at least one carcass layer extending in a toroidal shape across the pair of bead portions; At least one belt layer disposed radially outward of a crown portion of the carcass layer; At least one belt reinforcing layer disposed radially outward of the belt layer, A tire, wherein at least one of the carcass layers or at least one of the belt reinforcing layers, or at least one of the carcass layers and at least one of the belt reinforcing layers, is the rubber-organic fiber cord composite according to any one of claims 1 to 8.

10. 10. The tire according to claim 9, wherein at least one of said belt reinforcing layers is said rubber-organic fiber cord composite.

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