Rubber-reinforcing cord and rubber product using the same

Abstract

A rubber-reinforcing cord (62) of the present invention is a rubber-reinforcing cord for reinforcing a rubber product (60), and has at least one thread. The thread includes at least one tow, and a first coating film provided so as to cover at least a part of a surface of the tow. The tow includes a carbon fiber filament. The first coating film includes a rubber component and a cross-linking agent. The rubber-reinforcing cord (62) further includes a liquid component, and the content of the liquid component in the rubber-reinforcing cord (62) is in a range of 0.2 mass% or more and 13 mass% or less.

Description

Technical Field

[0001] This invention relates to rubber-reinforced cords and rubber articles using the rubber-reinforced cords. Background Technology

[0002] As a reinforcing material for rubber products such as rubber belts and tires that are repeatedly subjected to bending stress, rubber reinforcing cords formed of fibers are widely used. Since rubber reinforcing cords are used as tensile agents to improve the dimensional stability of rubber products, high tensile modulus and high tensile strength are desirable. Using rubber reinforcing cords with high tensile modulus can achieve, for example, rubber belts with high torque and high transmission efficiency.

[0003] The manufacturing process of rubber-reinforced cords typically includes coating the fibers with a treatment agent containing resorcinol-formaldehyde-rubber latex (RFL) and then drying it (RFL treatment process). Alternatively, as the treatment agent applied to the fibers, sometimes a treatment agent containing a material that is cross-linked through heat treatment and does not contain resorcinol-formaldehyde condensate is used. Using a coating formed by such a treatment agent, the adhesion between the rubber-reinforced cord and the base rubber can be improved when the rubber-reinforced cord is embedded in the rubber composition (base rubber) constituting the rubber article.

[0004] To achieve a high tensile modulus, the fibers used in rubber-reinforced cords are those with a high tensile modulus. Carbon fiber is an example of such a fiber. For instance, Patent Document 1 discloses rubber-reinforced cords using carbon fiber.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2012 / 169207 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, despite using carbon fibers with high tensile modulus, conventional rubber-reinforced cords using carbon fibers have failed to achieve the desired level of tensile modulus.

[0010] Therefore, one object of the present invention is to provide a rubber-reinforced cord that includes carbon fiber as a reinforcing fiber and improves the tensile modulus of elasticity. Furthermore, another object of the present invention is to provide a rubber article reinforced by such a rubber-reinforced cord that has a high tensile modulus of elasticity.

[0011] Methods for solving problems

[0012] This invention provides a rubber-reinforced cord from one aspect.

[0013] It is used to reinforce rubber products.

[0014] The aforementioned rubber-reinforced cord has at least one strand.

[0015] The aforementioned thread comprises at least one filament bundle and a first coating disposed in such a manner as to cover at least a portion of the surface of the filament bundle.

[0016] The aforementioned filament bundle contains carbon fiber filaments.

[0017] The first coating mentioned above contains a rubber component and a crosslinking agent.

[0018] The aforementioned rubber-reinforced cord further contains a liquid component.

[0019] The content of the liquid component in the rubber-reinforced cord is in the range of 0.2% by mass or more and 13% by mass or less.

[0020] The present invention provides a rubber article comprising, from another aspect, a rubber article comprising:

[0021] Matrix rubber, and

[0022] The aforementioned rubber-reinforced cord.

[0023] The present invention provides, from another aspect, a method for manufacturing rubber-reinforced cords, which is used to manufacture rubber-reinforced cords according to one aspect of the present invention.

[0024] The above manufacturing method includes:

[0025] (a) Bundling together multiple filaments containing carbon fiber strands to form at least one filament bundle; and

[0026] (b) The first coating is formed to produce the yarn by covering at least a portion of the surface of the aforementioned yarn bundle.

[0027] Invention Effects

[0028] According to the present invention, it is possible to provide a rubber-reinforced cord that includes carbon fiber as a reinforcing fiber and improves the tensile modulus of elasticity. Furthermore, according to the present invention, it is possible to provide a high-strength rubber article reinforced by such a rubber-reinforced cord, which has a high tensile modulus of elasticity. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view showing an example of the yarn material for the rubber-reinforced cord according to the first embodiment of the present invention.

[0030] Figure 2This is a cross-sectional view showing an example of a rubber-reinforced cord according to the first embodiment of the present invention.

[0031] Figure 3 This is a cross-sectional view showing another example of a rubber-reinforced cord according to the first embodiment of the present invention, which is a rubber-reinforced cord having multiple strands.

[0032] Figure 4 This is a cross-sectional view of a rubber-reinforced cord having multiple strands, which is another example of a rubber-reinforced cord according to the first embodiment of the present invention.

[0033] Figure 5 This is a cross-sectional view of a rubber-reinforced cord having multiple strands, which is another example of a rubber-reinforced cord according to the first embodiment of the present invention.

[0034] Figure 6 This is a partially exploded perspective view schematically illustrating an example of a rubber article according to the second embodiment of the present invention.

[0035] Figure 7 This is a cross-sectional view showing the rubber-reinforced cords obtained in Examples 11-13 and Comparative Example 3.

[0036] Figure 8 This is a cross-sectional view showing the rubber-reinforced cord obtained in Example 21 and Comparative Example 8. Detailed Implementation

[0037] (The process of achieving this invention)

[0038] As described in the [Background Art] section, carbon fiber, as a fiber used in rubber-reinforced cords, is a fiber with a high tensile modulus of elasticity, and is suitable for use, for example, in reinforcing cords for power transmission rubber belts. However, despite the use of fibers with high tensile modulus of elasticity in conventional rubber-reinforced cords using carbon fiber, the desired level of tensile modulus of elasticity has not been achieved. Therefore, the inventors have conducted in-depth research on rubber-reinforced cords using carbon fiber and have obtained the following insights.

[0039] Rubber-reinforced cords using carbon fibers can be obtained, for example, by coating carbon fibers with a coating-forming agent and then drying them. This invention focuses on the drying of the coating-forming agent and has found that the content of liquid components such as water in the coating affects the tensile modulus of elasticity of the rubber-reinforced cord. For example, rubber-reinforced cords having a coating formed from a treatment agent containing a material crosslinked by heat treatment are typically designed to undergo a curing reaction during the manufacture of rubber products, after the rubber-reinforced cord is placed within a matrix rubber, by heat treatment to crosslink the matrix rubber. However, such a curing reaction also occurs when the treatment agent is dried to form the coating. If the coating becomes too stiff due to such a curing reaction, for example, the bundle strength during twisting will decrease, resulting in a decrease in the tensile modulus of elasticity of the resulting rubber-reinforced cord. The inventors have further investigated methods to solve this problem and found that the content of liquid components affects the curing of the coating, which in turn affects the tensile modulus of elasticity of the rubber-reinforced cord.

[0040] Based on the newly obtained insights above, the inventors have achieved the following description of the rubber-reinforced cord of the present invention, and the rubber article of the present invention using such a rubber-reinforced cord.

[0041] The present invention will now be described in detail; however, this description is not intended to limit the invention to specific embodiments.

[0042] (One aspect of the present invention)

[0043] The rubber reinforcing cord of the first embodiment of the present invention is used to reinforce rubber products.

[0044] The aforementioned rubber-reinforced cord has at least one strand.

[0045] The aforementioned thread comprises at least one filament bundle and a first coating disposed in such a manner as to cover at least a portion of the surface of the filament bundle.

[0046] The aforementioned filament bundle contains carbon fiber filaments.

[0047] The first coating mentioned above contains a rubber component and a crosslinking agent.

[0048] The aforementioned rubber-reinforced cord further contains a liquid component.

[0049] The content of the liquid component in the rubber-reinforced cord is in the range of 0.2% by mass or more and 13% by mass or less.

[0050] In the second aspect of the present invention, for example in the rubber-reinforced cord of the first aspect, the content of the liquid component in the rubber-reinforced cord may be in the range of 0.2% by mass or more and 5% by mass or less.

[0051] In a third aspect of the present invention, for example in the rubber-reinforced cord of the first or second aspect, the rubber component may include at least one selected from nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber.

[0052] In the fourth aspect of the present invention, for example in the rubber-reinforced cord of any of the first to third aspects, the crosslinking agent may include at least one selected from maleimide-based crosslinking agents and isocyanate compounds.

[0053] In the fifth aspect of the present invention, for example in the rubber-reinforced cord of any of the first to fourth aspects, the first coating may not contain resorcinol-formaldehyde condensate.

[0054] In the sixth aspect of the present invention, for example in the rubber-reinforced cord of any of the first to fifth aspects, the mass of the first coating film may be in the range of 5% or more and 35% or less relative to the mass of the filament bundle.

[0055] In the seventh aspect of the present invention, for example, the rubber-reinforced cord of any of the first to sixth aspects may further include a second sheath disposed on the first sheath.

[0056] In the eighth aspect of the present invention, for example, in the rubber-reinforced cord of any of the first to seventh aspects, the thickness of the aforementioned filament bundle can be 400 tex or more and 3200 tex or less.

[0057] In the ninth aspect of the present invention, for example in the rubber-reinforced cord of the eighth aspect, the thickness of the aforementioned filament bundle can be 800 tex or more and 1600 tex or less.

[0058] In the tenth aspect of the present invention, for example, in the rubber-reinforced cord of any of the first to ninth aspects, it may include carbon fiber cord as the cord material and a plurality of glass fiber cords disposed around the carbon fiber cord material, wherein the glass fiber cord material comprises a bundle of glass fiber filaments containing glass fiber strands.

[0059] In the eleventh aspect of the present invention, for example in the rubber-reinforced cord of the tenth aspect, the total cross-sectional area of ​​the carbon fiber strand can be in the range of 20% to 80% of the sum of the total cross-sectional area of ​​the carbon fiber strand and the total cross-sectional area of ​​the glass fiber strand.

[0060] The rubber article of the 12th aspect of the present invention comprises:

[0061] Matrix rubber, and

[0062] Rubber-reinforced cord of any of the 1st to 11th types.

[0063] In the 13th aspect of the present invention, for example in the rubber article of the 12th aspect,

[0064] The aforementioned rubber-reinforced cords can be embedded in the aforementioned matrix rubber.

[0065] In the 14th aspect of the present invention, for example, the rubber product of the 12th or 13th aspect can be a rubber belt.

[0066] The method for manufacturing rubber-reinforced cord according to the 15th aspect of the present invention is used to manufacture rubber-reinforced cords according to any of the 1st to 11th aspects.

[0067] The above manufacturing method includes:

[0068] (a) Bundling together multiple filaments containing carbon fiber strands to form at least one filament bundle; and

[0069] (b) The first coating is formed to produce the yarn by covering at least a portion of the surface of the aforementioned yarn bundle.

[0070] In the 16th aspect of the present invention, for example in the method of manufacturing rubber-reinforced cord in the 15th aspect, in (b) above, after forming the first coating in a manner that covers at least a portion of the surface of the filament bundle, the filament bundle with the first coating formed is twisted to form the cord material.

[0071] In the 17th aspect of the present invention, for example in the method of manufacturing rubber-reinforced cord in the 15th aspect, in (b) above, the first coating can be formed by covering at least a portion of the surface of the twisted filament bundle after twisting the filament bundle, thereby forming the cord material.

[0072] (First Embodiment)

[0073] As a first embodiment, an embodiment of the rubber-reinforced cord of the present invention will be described.

[0074] The rubber-reinforcing cord of this embodiment is a cord used to reinforce rubber products. This rubber-reinforcing cord includes at least one strand. The strand comprises at least one filament bundle and a first coating film disposed to cover at least a portion of the surface of the filament bundle. The filament bundle comprises carbon fiber filaments. The first coating film comprises a rubber component and a crosslinking agent. The rubber-reinforcing cord of this embodiment further comprises a liquid component, the content of which is in the range of 0.2% by mass or more and 13% by mass or less. With this configuration, the temperature rise of the rubber-reinforcing cord during coating film formation, i.e., the curing reaction of the coating film, can be suppressed, thereby suppressing the decrease in the tensile modulus of elasticity or the degree of compression reduction of the rubber-reinforcing cord caused by coating film formation. It should be noted that the liquid component contained in the rubber-reinforcing cord may be, for example, a solvent contained in the aqueous treatment agent used in the production of the first coating film (the first coating film is made with an aqueous treatment agent), residual moisture from the filament itself, etc. For example, the liquid component described above may also be composed of a liquid having a boiling point lower than that of the solvent with the highest boiling point among the solvents contained in the treatment agent used to form the film, and a heat of vaporization lower than that of the solvent with the highest heat of vaporization among the solvents contained in the treatment agent used to form the film. As an example, when the first and second films are formed as films, water is used as the solvent for forming the first film, and xylene is used as the solvent for forming the second film, the liquid component may, for example, be composed of a liquid having a boiling point lower than that of xylene and a heat of vaporization lower than that of water. The liquid component may, for example, be water.

[0075] The manufacturing method of the reinforcing cord according to this embodiment will be described in more detail below.

[0076] In this embodiment of the rubber-reinforced cord, the filament bundle constituting the cord comprises multiple filaments. The proportion of carbon fiber filaments in the cross-sectional area of ​​the filament bundle can be, for example, 30% or more. As described above, the filament bundle comprises carbon fiber filaments. In this embodiment, the filament bundle may contain carbon fiber filaments as the main component, or it may be substantially composed solely of carbon fiber filaments. Here, "the filament bundle contains carbon fiber filaments as the main component" means that the filaments occupying the largest proportion in 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 can be, for example, 50% or more. Furthermore, "the filament bundle is substantially composed 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, for example, 95% or more, or 99% or more. As filaments other than carbon fiber filaments, filaments of fibers commonly used as reinforcing fibers for rubber-reinforced cords can be used, for example, glass fiber filaments.

[0077] There is no particular limitation on the number of filaments contained in the filament bundle. For example, the filament bundle may contain 1,000 to 48,000 filaments. It is preferable to contain 6,000 to 48,000 filaments. It is even more preferable to contain 12,000 to 24,000 filaments.

[0078] The thickness of the filament bundle can be, for example, 400 tex or more and 3200 tex or less, or 800 tex or more and 1600 tex or less. When such thick filament bundles form a coating, the drying temperature or drying time during coating formation is usually higher or longer because the interior of the bundle is difficult to dry. This intensifies the surface curing reaction, causing the surface to harden and making it difficult to obtain rubber-reinforced cords with high elastic modulus. Furthermore, carbon fibers, for example, have a higher elastic modulus than other fibers such as aramid fibers, making them susceptible to the decrease in elastic modulus that occurs during coating formation. However, the rubber-reinforced cord of this embodiment, by setting the liquid component content to a range of 0.2% by mass or more and 13% by mass or less, can suppress the decrease in tensile elastic modulus or the degree of compression reduction in the rubber-reinforced cord caused by coating formation, even when using filament bundles containing carbon fiber filaments within the aforementioned thickness range, thus achieving a rubber-reinforced cord with high elastic modulus.

[0079] Pretreatment is preferably performed on the surface of the carbon fiber filaments contained in the tow to improve the bonding strength. A preferred example of a pretreatment agent is a compound containing at least one functional group selected from epoxy and amino groups. Examples of pretreatment agents include aminosilanes, epoxysilanes, linear phenolic epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, brominated epoxy resins, bisphenol AD ​​epoxy resins, glycidylamine epoxy resins, etc. Specific examples include the Denacol series from Nagase ChemteX, the Epiclon series from DIC, and the Epikote series from Mitsubishi Chemical. Alternatively, polyurethane resins and isocyanate compounds can also be used as pretreatment agents. For example, a pretreatment agent containing at least one of epoxy resins, polyurethane resins, and isocyanate compounds can be used. By using such a pretreatment agent, a resin layer containing at least one of epoxy resins, polyurethane resins, and isocyanate compounds is further formed between the tow and the first coating. By using pre-treated carbon fiber filaments, the adhesion between the matrix rubber and the rubber-reinforced cord can be improved. When the bundle contains other fibers besides carbon fiber filaments (e.g., glass fiber filaments), it is preferable to also pre-treat the surface of these fibers as described above to improve adhesive strength.

[0080] There is no limit to the number of filament bundles contained in rubber-reinforced cords; there can be one or more. A filament bundle can also be a bundle of multiple filament bundles bound together. In this case, each of the multiple filament bundles may or may not be twisted individually. Furthermore, multiple filament bundles may be twisted together while still in a combined state, or they may not be twisted at all.

[0081] The first coating is provided in such a way that it covers at least a portion of the surface of the filament bundle. It should be noted that the first coating can be provided directly on the surface of the filament bundle, or it can cover the surface of the filament bundle by sandwiching other layers (such as coatings formed by the pretreatment of the filaments described above (such as the resin layer described above)).

[0082] The first coating is formed by supplying at least a portion of the surface of the filament bundle with the first coating aqueous treatment agent (described later) and drying it by heat treatment. The supply of the first aqueous treatment agent to the surface of the filament bundle can be carried out, for example, by immersing the filament bundle in the first coating aqueous treatment agent or by coating at least a portion of the surface of the filament bundle with the first coating aqueous treatment agent. It should be noted that, through this heat treatment, most of the moisture inherent in the filament itself and the solvent (e.g., water) of the aqueous treatment agent are removed.

[0083] The first coating comprises a rubber component. The rubber component preferably comprises at least one selected from nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber. The first coating may comprise only one of the aforementioned rubbers, or it may comprise multiple types of rubber. It should be noted that, unless otherwise specified, the term "nitrile rubber" in this specification refers to nitrile rubber (acrylonitrile-butadiene copolymer rubber) that is neither hydrogenated nor carboxyl-modified.

[0084] The first coating may also include other rubbers besides the aforementioned rubbers. Examples of other rubbers include butadiene-styrene copolymers, dicarboxylated butadiene-styrene copolymers, vinylpyridine-butadiene-styrene copolymers, chloroprene rubber, butadiene rubber, and chlorosulfonated polyethylene.

[0085] The first coating further comprises a crosslinking agent. By including a crosslinking agent in the first coating, the adhesion between the rubber-reinforced cord and the matrix rubber of this embodiment can be improved. Examples of crosslinking agents include quinone dioxime crosslinking agents such as p-quinone dioxime, methacrylate crosslinking agents such as lauryl methacrylate and methyl methacrylate, allyl crosslinking agents such as DAF (dallyl fumarate), DAP (dallyl phthalate), TAC (tracelyl cyanurate), and TAIC (tracelyl isocyanurate), maleimide crosslinking agents such as bismaleimide, phenylmaleimide, and N,N'-m-phenylenebismaleimide, aromatic or aliphatic organic diisocyanates, polyisocyanates, capped isocyanates, and isocyanate compounds such as capped polyisocyanates, aromatic nitroso compounds, sulfur, and peroxides. These crosslinking agents can be used alone or in combination. These crosslinking agents are preferably selected considering the type of rubber contained in the first coating and the type of matrix rubber in which the rubber reinforcing cords are embedded. It should be noted that, in order to ensure that the crosslinking agents are uniformly present in the aqueous treatment agent used to make the first coating, it is preferable to use these crosslinking agents in the form of an aqueous dispersion.

[0086] The crosslinking agent preferably comprises at least one selected from maleimide-based crosslinking agents and isocyanate compounds. Among maleimide-based crosslinking agents, 4,4'-bismaleimide diphenylmethane is suitable for use due to its good stability when dispersed in water, high crosslinking effect, and high heat resistance after crosslinking. For example, a terminal isocyanate is used as the isocyanate compound. By combining the maleimide-based crosslinking agent and the isocyanate compound with the rubber latex, the adhesion between the reinforcing cord and the matrix rubber can be specifically improved. In particular, the combination of carboxyl-modified hydrogenated nitrile butadiene rubber latex and the maleimide-based crosslinking agent further improves adhesion and is therefore preferred.

[0087] The first coating may further comprise a filler material. Examples of filler materials include particles of covalently bonded compounds such as carbon black and silica, particles of sparingly soluble salts, particles of metal oxides, particles of metal hydroxides, and particles of complex metal oxide salts such as talc. Preferably, at least one of carbon black and silica is selected from these.

[0088] The average particle size of carbon black is preferably in the range of 5–300 nm, for example, in the range of 100–200 nm, and more preferably in the range of 130–170 nm. The average particle size of silica is preferably in the range of 5–200 nm, for example, in the range of 7–100 nm, and more preferably in the range of 7–30 nm. The average particle size referred to here is the value obtained by measuring the particle size of 50 or more particles using a transmission electron microscope and dividing the total particle size by the number of particles measured. It should be noted that when the particles are not spherical, the average of the longest and shortest diameters of each particle is taken as the particle size.

[0089] Fillers, by being dispersed within rubber, enhance the tensile and tear strength of the coating. In addition to these effects, fillers further improve adhesive strength by increasing the cohesiveness of the bonding components between the fibers and the coating, and between the coating and the base rubber. It should be noted that the particle size and dosage of the filler significantly influence these effects.

[0090] The first membrane preferably does not contain resorcinol-formaldehyde condensate. In this case, when manufacturing the first membrane, environmentally burdensome substances such as formaldehyde and ammonia can be avoided, thus eliminating the need for environmental protection measures for operators.

[0091] The first coating may further include filler materials and other components (such as metal oxides other than metal oxides, resins, etc. added as filler materials) in addition to the rubber components and crosslinking agents.

[0092] The content of the rubber component and the crosslinking agent in the first coating is not particularly limited. For example, the content of the rubber component in the first coating can be 50% by mass or more and 90% by mass or less. In addition, the content of the crosslinking agent in the first coating can be, for example, in the range of 10% by mass or more and 50% by mass or less.

[0093] The mass of the first coating, which is applied to at least the surface of the filament bundle, is not particularly limited and can be adjusted appropriately; however, it is preferably set to a range of 5% to 35% of the mass of the filament bundle. The mass of the first coating can also be in the range of 10% to 25% of the mass of the filament bundle, or 12% to 22%. If the mass of the first coating is too high, there may be adverse effects such as reduced dimensional stability of the rubber reinforcing cord within the rubber product and reduced elastic modulus of the rubber reinforcing cord. On the other hand, if the mass of the first coating is too low, the yarn may easily become loose, or the function of the first coating in protecting the fibers may be reduced, resulting in a reduced lifespan of the rubber product.

[0094] To improve adhesion to the matrix rubber, the rubber-reinforced cord of this embodiment may further include a second coating formed on the first coating. The treatment agent for forming the second coating may be the same as or different from the aqueous treatment agent for the first coating. For example, the second coating may be formed using a treatment agent with different components and solvents than the aqueous treatment agent for the first coating. To further improve adhesion to the matrix rubber, another coating layer may be provided on the second coating.

[0095] The number of twists in the rubber-reinforced cord of this embodiment is not particularly limited. The number of twists applied to a single cord (hereinafter sometimes referred to as initial twist) can be, for example, in the range of 20 to 160 twists / m, 30 to 120 twists / m, or 40 to 100 twists / m. Similarly, the number of twists applied to multiple cords (hereinafter sometimes referred to as re-twisting) can also be, for example, in the range of 20 to 160 twists / m, 30 to 120 twists / m, or 40 to 100 twists / m. It can be a unidirectional twist where the initial twist direction is the same as the re-twisting direction, or a multidirectional twist where the initial twist direction is opposite to the re-twisting direction. The direction of twisting is not limited; it can be the S-direction or the Z-direction.

[0096] The liquid component content in the rubber-reinforced cord of this embodiment is in the range of 0.2% by mass or more and 13% by mass or less. It should be noted that, as described above, this so-called liquid component includes, for example, residual solvents (e.g., water) contained in the aqueous treatment agent used during the coating process, and residual moisture inherent in the filament itself. In the rubber-reinforced cord of this embodiment, during the heat treatment for the production of the first coating, the heat of the heat treatment is adjusted so that the liquid component remaining in the rubber-reinforced cord is in the range of 0.2% by mass or more and 13% by mass or less. This suppresses the temperature rise of the rubber-reinforced cord, i.e., the curing reaction of the coating. Therefore, it is possible to prevent the rubber-reinforced cord from becoming too stiff due to intensified curing reaction of the coating, and to suppress the decrease or compression reduction of the tensile modulus of elasticity of the rubber-reinforced cord compared to conventional methods. As a result, the tensile modulus of elasticity of the rubber-reinforced cord can be increased compared to conventional methods, achieving a higher tensile modulus of elasticity than before. When the liquid component content is less than 0.2% by mass, i.e., when the heat treatment during coating production is carried out in a manner that removes almost all the solvent of the treatment agent used to make the coating and the moisture contained in the fiber, the tensile modulus of elasticity of the rubber-reinforced cord decreases due to the intensified curing reaction of the coating of the resulting rubber-reinforced cord. As a result, the tensile strength of the rubber-reinforced cord also decreases. On the other hand, when the liquid component content is greater than 13% by mass, it is difficult, for example, to twist the yarn to produce the cord.

[0097] In order to obtain rubber-reinforced cords with higher tensile modulus, the content of liquid components in the rubber-reinforced cords is preferably 0.2% by mass or more and 5% by mass or less.

[0098] Here, the "content of liquid component in rubber-reinforced cord" specified in this invention is calculated as follows: A 5m length of cord is collected from the rubber-reinforced cord as a sample. The sample is measured using an electronic balance, and its value is set as the mass A of the cord. The sample is placed in a dryer heated to 150°C for 30 minutes to remove the solvent. After being placed in the dryer for another 30 minutes, the sample is measured using an electronic balance, and the resulting value is set as the mass B. The difference between mass A and mass B is set as the mass (AB) of the liquid component contained in the cord. The percentage of the mass (AB) of the liquid component contained in the cord relative to the mass A of the cord ({(AB) / A}×100) is set as the content (%) of the liquid component. It should be noted that here, it is assumed that the solvent of the treatment agent is water. In order to completely remove water from the sample, a heat treatment of 150°C for 30 minutes is performed. When using a solvent other than water, it is sufficient to set an appropriate heating temperature and heating time in a way that can completely remove the solvent.

[0099] An example of a method for manufacturing the rubber-reinforced cord of this embodiment is described below. It should be noted that since the matters described for the rubber-reinforced cord of this embodiment can be applied to the manufacturing method described below, repeated descriptions are sometimes omitted. Furthermore, the matters described in the manufacturing method described below can be applied to the rubber-reinforced cord of this embodiment.

[0100] An example of a method for manufacturing rubber-reinforced cord according to this embodiment includes:

[0101] (a) Bundling together multiple filaments containing carbon fiber strands to form at least one filament bundle; and

[0102] (b) The first coating is formed to produce the yarn by covering at least a portion of the surface of the aforementioned yarn bundle.

[0103] First, multiple filaments are bundled together to form a filament bundle. Additionally, an aqueous treatment agent (the first coating is treated with an aqueous treatment agent) is prepared, for example, during the fabrication of the first coating. Then, the aqueous treatment agent is supplied to at least a portion of the surface of the filament bundle, followed by a heat treatment to remove solvent from the aqueous treatment agent. As a specific example, 12,000 filaments are first bundled together, and the aqueous treatment agent is supplied to the surface of the bundle. Subsequently, the solvent in the aqueous treatment agent is removed by heat treatment. The filament bundle contains carbon fiber filaments.

[0104] Through the above process, at least a portion of the surface of the filament bundle forms a first coating, and has, for example, as shown in the figure above. Figure 1 The cross-section of the wire shown. Figure 1 In the example of a thread, a thread 10 is shown, comprising a bundle of filaments 11 and a first coating 12 covering the surface of the bundle of filaments 11. Figure 1 The thread material 10 shown can also be used as a rubber-reinforced cord. That is, the rubber-reinforced cord of this embodiment, as an example, can have the following characteristics: Figure 1 The diagram shows a configuration in which a first coating 12 is formed on the surface of a single filament bundle 11. However, the rubber-reinforced cord of this embodiment is not limited to this; the cord can also be formed by combining multiple filament bundles together and forming a first coating on their surfaces. Furthermore, the method of supplying the first coating to at least a portion of the surface of the filament bundle with an aqueous treatment agent is not limited; for example, the first coating can be coated onto the surface of the filament bundle with the aqueous treatment agent, or the filament bundle can be immersed in the first coating in the aqueous treatment agent. The material constituting the first coating 12 can be wholly or partially permeated into the filament bundle 11. That is, Figure 1 The component represented by symbol 11 may contain materials of filament bundles and a first membrane.

[0105] The conditions for heat treatment to remove the solvent from the first coating using an aqueous treatment agent are not particularly limited. However, the treatment temperature and time should be appropriately adjusted to ensure that the liquid content of the resulting cord after heat treatment is 0.2% by mass or more and 13% by mass or less. Preferably, the treatment temperature and time should be appropriately adjusted to ensure that the liquid content of the resulting cord after heat treatment is 0.2% by mass or more and 5% by mass or less. The treatment temperature is, for example, preferably 220°C or less. The treatment time is not particularly limited, and the heat applied can be appropriately adjusted to ensure that the liquid content in the final rubber-reinforced cord is within the range specified in this embodiment (0.2% by mass or more and 13% by mass or less). During heat treatment, the appropriate treatment temperature can be adjusted according to the liquid to be removed, or the treatment time can be adjusted instead of the treatment temperature. For example, if the processing temperature has been set to a temperature suitable for water removal, and the liquid to be removed contains liquid components with a heat of vaporization higher than that of water, the processing time can be extended, for example, at the same processing temperature. If the liquid to be removed contains liquid components with a heat of vaporization lower than that of water, the processing time can be shortened, for example, at the same processing temperature.

[0106] In the process described in (b) above, after forming the first coating to cover at least a portion of the surface of the filament bundle, the filament bundle with the first coating is twisted to form a thread. In this case, the filament bundle with the first coating is twisted in one direction, for example. The twisting direction can be either the S direction or the Z direction. The number of filaments contained in the filament bundle and the number of twists of the filament bundle have been described above, so the description is omitted. In this way, the rubber-reinforced cord of this embodiment can be manufactured. It should be noted that it is also possible to form a bundle of multiple filaments with the first coating, and then apply retwisting after bundling these multiple filament bundles. The direction of retwisting can be the same as or different from the twisting direction (the direction of the initial twist) of the filament bundle. Alternatively, it is also possible to form multiple filament bundles with the first coating, and instead of twisting the filament bundles individually, the multiple filament bundles are bundled together and then twisted.

[0107] It should be noted that the first coating can also be formed after twisting the filament bundle. That is, in the process described in (b) above, the first coating can be formed after twisting the filament bundle in a manner that covers at least a portion of the surface of the twisted filament bundle, thereby forming the yarn. In this case, the type, quantity, and twist count of the filaments are as described above.

[0108] In a preferred embodiment of the manufacturing method, after forming a first coating by coating or impregnating the filament bundle with an aqueous treatment agent, the first coating is twisted in one direction to form a rubber-reinforced cord.

[0109] When forming a second coating on a first coating, a treatment agent for forming the second coating is applied to the first coating, and the solvent in the treatment agent is removed, thereby forming the second coating. The type of the second coating can be appropriately selected according to the base rubber of the rubber product to which the rubber reinforcing cord is applied, and it is particularly desirable to select it from the viewpoint of improving adhesion. Figure 2 This section shows an example of a rubber-reinforced cord having a second sheath disposed on a first sheath. Figure 2 In the example of rubber-reinforced cord, it is shown that it further possesses the ability to be formed in Figure 1 The rubber-reinforced cord 20 is a second sheath 21 on the first sheath 12 of the thread material 10 shown.

[0110] The conditions for heat treatment to remove the solvent from the second coating agent are not particularly limited; however, it is preferable to adjust the treatment temperature and treatment time appropriately in a way that the liquid content of the cord obtained after heat treatment meets the above-mentioned range.

[0111] The first membrane is then described using an aqueous treatment agent.

[0112] The aqueous treatment agent for the first coating preferably comprises a latex selected from at least one type of rubber selected from nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber. The aqueous treatment agent may contain only one type of these rubber latexes or may contain multiple types of these rubber latexes.

[0113] The water-based treatment agent for the first coating may include other rubber latexes besides those mentioned above. Examples of other rubber latexes include butadiene-styrene copolymer latex, dicarboxylated butadiene-styrene copolymer latex, vinylpyridine-butadiene-styrene trimer latex, chloroprene latex, butadiene latex, and chlorosulfonated polyethylene latex. The water-based treatment agent may also contain a variety of these rubber latexes.

[0114] The first membrane further comprises a crosslinking agent in the aqueous treatment agent. Since the crosslinking agent contained in the first membrane is the same as the crosslinking agent described above as contained in the first membrane, its description is omitted here. It should be noted that, in order to ensure that the crosslinking agent is uniformly present in the aqueous treatment agent, it is preferable to use it in the form of an aqueous dispersion.

[0115] The first membrane may further include a filler material in the aqueous treatment agent. Since the filler material contained in the first membrane in the aqueous treatment agent is the same as the filler material described above as contained in the first membrane, its description is omitted here.

[0116] The first membrane-coating water-based treatment agent preferably does not contain resorcinol-formaldehyde condensate.

[0117] The water-based treatment agent for the first coating may include fillers and other components in addition to the rubber latex and crosslinking agent. For example, the water-based treatment agent for the first coating may include resin, plasticizer, anti-aging agent, stabilizer, and metal oxides other than metal oxides added as fillers. However, the water-based treatment agent may also not contain resin.

[0118] In the above description, the rubber-reinforced cord of this embodiment was mainly described as follows: Figure 1 and Figure 2 The example shown is a rubber-reinforced cord with one strand; however, the rubber-reinforced cord of this embodiment is not limited to this. Hereinafter, another example of the rubber-reinforced cord of this embodiment will be described.

[0119] The rubber-reinforced cord of this embodiment can also have multiple strands. Figure 3 In this embodiment, another example of a rubber-reinforced cord is shown, which is a rubber-reinforced cord having multiple strands.

[0120] Figure 3The rubber-reinforced cord 30 shown includes a carbon fiber strand 31 and a plurality of glass fiber strands 32 disposed around the carbon fiber strand 31. The carbon fiber strand 31 comprises a bundle of carbon fiber filaments 33 and a first coating 34 disposed to cover at least a portion of the surface of the bundle 33. The glass fiber strands 32 comprise a bundle 35 containing glass fiber filaments and a first coating 36 disposed to cover at least a portion of the surface of the bundle 35. The carbon fiber strand 31 disposed in this manner on the central side of the cord contributes to high tensile strength and excellent dimensional stability. By surrounding the carbon fiber strand 31 with the glass fiber strands 32, tensile stress and compressive stress can be alleviated, thereby improving the bending fatigue resistance of the reinforcing cord 30. It should be noted that the bundle 33 containing carbon fiber filaments may or may not be formed solely of carbon fiber filaments. Similarly, the bundle 35 containing glass fiber filaments may or may not be formed solely of glass fiber filaments.

[0121] The total cross-sectional area of ​​the carbon fiber strand 31 is preferably in the range of 20% to 80% of the sum of the total cross-sectional area of ​​the carbon fiber strand 32 and the total cross-sectional area of ​​the glass fiber strand. As described above, the carbon fiber strand 31 disposed on the central side of the cord contributes to high tensile strength and excellent dimensional stability. However, if the proportion of carbon fiber strand 31 in the cord is too high, the flexibility will decrease. Therefore, the total cross-sectional area of ​​the carbon fiber strand 31 is preferably 80% or less of the sum of the total cross-sectional area of ​​the carbon fiber strand 31 and the total cross-sectional area of ​​the glass fiber strand 32, more preferably 70% or less. On the other hand, if the proportion of carbon fiber strand 31 in the cord is too low, the effects brought by the carbon fiber strand 31 may not be fully obtained. Therefore, the total cross-sectional area of ​​the carbon fiber strand 31 is preferably 20% or more of the sum of the total cross-sectional area of ​​the carbon fiber strand 31 and the total cross-sectional area of ​​the glass fiber strand 32, more preferably 40% or more.

[0122] The quantity of carbon fiber strands 31 and the quantity of glass fiber strands 32 can be selected according to the required properties of the cord and the properties of the strands. Preferred examples of the ratio of [quantity of carbon fiber strands] / [quantity of glass fiber strands] include, for example, [1] / [3-30], [2] / [6-30] and [3] / [10-40].

[0123] In the rubber-reinforced cord comprising carbon fiber strands and multiple glass fiber strands disposed around the carbon fiber strands as described above, a second coating may be further formed on the first coating. That is, it may also have a structure like... Figure 4The rubber-reinforced cord 40 shown has the following structure: it includes a carbon fiber cord 31 and multiple glass fiber cords 32 disposed around the carbon fiber cord 31, and a second coating 41 is further provided on the first coating 35 of the glass fiber cords 32. In this case, it is preferable to use a cord like... Figure 4 The rubber-reinforced cord 40 shown has the following configuration: multiple glass fiber strands 32 are closely arranged around the carbon fiber strand 31, so that the second sheath 41 does not contact the surface of the carbon fiber strand 31 (i.e., the first sheath 34 of the carbon fiber strand 31). This configuration, which prevents the second sheath 41 from contacting the surface of the carbon fiber strand 31, further improves the bending fatigue resistance of the rubber-reinforced cord. It should be noted that the aforementioned configuration of multiple glass fiber strands 32 closely arranged around the carbon fiber strand 31 includes, for example, the following configurations: the glass fiber strands 32 are arranged around the carbon fiber strand 31 such that the gaps between the glass fiber strands 32 are small enough that the second sheath 41 does not contact the surface of the carbon fiber strand 31; or the glass fiber strands 32 are arranged around the carbon fiber strand 31 without any gaps between them.

[0124] It can also be like Figure 5 As shown in the rubber-reinforced cord 50, the second sheath 41 contacts the surface of the carbon fiber cord 31 through the gap between the glass fiber cords 32.

[0125] (Second Implementation)

[0126] As a second embodiment, embodiments of the rubber product of the present invention will be described.

[0127] The rubber product of this embodiment includes a base rubber and the rubber reinforcing cord of the first embodiment. As described in the first embodiment, the rubber reinforcing cord of the first embodiment includes carbon fiber as a reinforcing fiber and has a higher tensile modulus of elasticity than conventional rubber reinforcing cords containing carbon fiber. By including such a rubber reinforcing cord, the rubber product of this embodiment can become a high-strength rubber product with a high tensile modulus of elasticity.

[0128] The rubber product of this embodiment is a rubber product reinforced with rubber-reinforcing cords as described in the first embodiment. The rubber product is not particularly limited. Examples of the rubber product of this embodiment include automobile and bicycle tires, and rubber belts such as drive belts. Examples of drive belts include meshing drive belts and friction drive belts. Examples of meshing drive belts include toothed belts, such as timing belts for automobiles. Examples of friction drive belts include flat belts, round belts, V-belts, and V-shaped multi-ribbed belts. That is, the rubber product of this embodiment can be a toothed belt, a flat belt, a round belt, a V-belt, or a V-shaped multi-ribbed belt.

[0129] The rubber product of this embodiment is formed by embedding the rubber reinforcing cord of this embodiment into a rubber composition (base rubber). The method of embedding the rubber reinforcing cord into the base rubber is not particularly limited, and known methods can be used. The rubber reinforcing cord of this embodiment is embedded in the rubber product (e.g., a rubber belt). Therefore, the rubber product of this embodiment has a high tensile modulus of elasticity. Consequently, the rubber product of this embodiment is particularly suitable for applications requiring high elastic modulus and strength, such as rear wheel drive belts for two-wheeled motorcycles, timing belts for vehicle engines, auxiliary drive belts for vehicles, and large industrial equipment.

[0130] The rubber composition in which the rubber reinforcing cord of this embodiment is embedded is not particularly limited in its composition, and may include chloroprene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, hydrogenated nitrile butadiene rubber, etc. The hydrogenated nitrile butadiene rubber may be a hydrogenated nitrile butadiene rubber dispersed with a zinc acrylate derivative (e.g., zinc methacrylate). From the viewpoint of water resistance and oil resistance, at least one rubber selected from hydrogenated nitrile butadiene rubber and hydrogenated nitrile butadiene rubber dispersed with a zinc acrylate derivative is preferred. The matrix rubber may further include carboxyl-modified hydrogenated nitrile butadiene rubber. It should be noted that, from the viewpoint of adhesion, the sheath of the rubber reinforcing cord and the rubber composition of the rubber article contain the same type of rubber, or are formed from the same type of rubber.

[0131] As an example of rubber products, toothed strips are represented as follows: Figure 6 middle. Figure 6 The toothed belt 60 shown includes a belt body 61 and a plurality of rubber reinforcing cords 62. The belt body 61 includes a belt portion 63 and a plurality of teeth 64 protruding from the belt portion 63 at intervals. The rubber reinforcing cords 62 are embedded in the interior of the belt portion 63 in a manner parallel to the length direction of the belt portion 63. The rubber reinforcing cords 62 are the rubber reinforcing cords of this embodiment.

[0132] Example

[0133] The following examples and comparative examples further illustrate the implementation of the present invention.

[0134] [Manufacturing of rubber-reinforced cords]

[0135] (Examples 1-10 and Comparative Example 1)

[0136] 12,000 carbon fiber filaments (average diameter approximately 7 μm) are bundled together and used as a filament bundle. A first coating with an aqueous treatment agent, as shown in Table 1 below, is applied to this filament bundle. The residence time in a drying oven set to 150°C is then adjusted to adjust the liquid content. A filament with the first coating formed on its surface is formed in this manner. The amount of aqueous treatment agent applied to the first coating is adjusted so that the mass of the formed first coating is 20% of the mass of the filament bundle. One filament prepared in this way is Z-twisted at a ratio of 60 twists / m. A second coating is formed on the surface of the resulting cord. The treatment agent used for the second coating is a composition obtained by mixing Chemlok 233X (manufactured by LORD JAPAN INC.) and xylene in a mass ratio of 1:1. The second coating is formed at 5% of the mass of the cord before the formation of the second coating (i.e., the filament with the first coating formed on the surface of the filament bundle). The drying of the second coating with the treatment agent is carried out at 130°C for 1 minute. This yields a rubber-reinforced cord. The resulting rubber-reinforced cord has the same properties as... Figure 2 The reinforcing cord shown has the same cross-section.

[0137] (Comparative Example 2)

[0138] As the first coating, an aqueous treatment agent was prepared by mixing 50 parts by weight of vinylpyridine-modified styrene-butadiene latex (Japan A&L), 50 parts by weight of styrene-butadiene latex (Nipol LX110, Japan ZEON), and 10 parts by weight of resorcinol-formaldehyde condensate (Sumikanol 700S, Sumitomo Chemical). The resulting mixture was then treated with an RFL treatment agent, the pH of which was adjusted to 10 using ammonia. This RFL treatment agent was applied to a tow prepared using the same method as in Examples 1-10 and Comparative Example 1. The tow was then treated in a drying oven set to 200°C for a residence time of 2 minutes. This formed a yarn. The amount of RFL treatment agent applied was adjusted so that the mass of the first coating was 20% of the mass of the tow. Subsequently, twisting and the formation of the second coating were performed using the same method as in Examples 1-10 and Comparative Example 1.

[0139] (Examples 11-13 and Comparative Example 3)

[0140] Using the aqueous treatment agent with the composition shown in Table 2 as the first coating, four yarns were Z-twisted at a ratio of 40 twists / m during the twisting process, and a second coating was formed after twisting. Otherwise, using the same method as Examples 1-10 and Comparative Example 1, rubber-reinforced cords of Examples 11-13 and Comparative Example 3 were obtained. The obtained rubber-reinforced cords have the following characteristics: Figure 7 The cross-section shown. Figure 7The cross section of the rubber-reinforced cord 70 is shown, wherein four carbon fiber strands 73, on the surface of the carbon fiber bundle 71, having a first coating 72 formed thereon, are twisted and further provided with a second coating 74.

[0141] (Example 14, Example 15, and Comparative Example 4)

[0142] The number of carbon fiber filaments bundled to make one filament bundle was changed to 24,000. A treatment agent with the composition shown in Table 3 was used as the first coating water-based treatment agent. In the twisting treatment, one filament was Z-twisted at a ratio of 40 twists / m. Otherwise, using the same method as Examples 1-10 and Comparative Example 1, rubber-reinforced cords of Examples 14, 15, and Comparative Example 4 were obtained. The resulting rubber-reinforced cords have the same characteristics as... Figure 2 The reinforcing cord shown has the same cross-section.

[0143] (Example 16, Example 17, and Comparative Example 5)

[0144] As the thread material disposed at the center, carbon fiber thread material with a first coating formed on the surface of a bundle composed of carbon fiber filaments was used. As the thread material disposed at the outer periphery of the carbon fiber thread material, glass fiber thread material with a first coating formed on the surface of a bundle composed of glass fiber filaments was used. The carbon fiber thread material was produced using the same method as the thread material produced in Examples 1-10 and Comparative Example 1. However, the water-based treatment agent used for the first coating was the treatment agent with the composition shown in Table 4. The glass fiber thread material was obtained by bundling 600 K glass filaments (manufactured by Nippon Sheet Glass Co., Ltd.) with an average diameter of 7 μm to form a bundle, and forming a first coating on the surface of the bundle, similar to that of the carbon fiber thread material. Glass fiber thread material obtained by first twisting 15 of the glass fiber thread material at a ratio of 80 twists / m was used. The drying conditions during the formation of the first coating were set so that the liquid component content of the glass fiber thread material was the same as that of the carbon fiber thread material. A carbon fiber filament is placed at the center, and 15 glass fiber filaments are arranged around it to further form a second coating. The second coating is manufactured using the same method as in Examples 1-10 and Comparative Example 1. The resulting rubber-reinforced cords (rubber-reinforced cords of Examples 16, 17, and Comparative Example 5) have the same characteristics as... Figure 4 The reinforcing cord shown has the same cross-section.

[0145] (Examples 18-20, Comparative Example 6)

[0146] Using an aqueous treatment agent with the composition shown in Table 5 as the first coating, and without forming a second coating, rubber-reinforced cords of Examples 18-20 and Comparative Example 6 were obtained using the same method as in Examples 1-10 and Comparative Example 1. The resulting rubber-reinforced cords are reinforcing cords without a second coating and have the same characteristics as... Figure 1 The reinforcing cord shown has the same cross-section.

[0147] (Comparative Example 7)

[0148] Except for the absence of a second coating, the rubber-reinforced cord of Comparative Example 7 was obtained using the same method as Comparative Example 2. The resulting rubber-reinforced cord is a reinforcing cord without a second coating, and has the same characteristics as Comparative Example 7. Figure 1 The reinforcing cord shown has the same cross-section.

[0149] (Example 21 and Comparative Example 8)

[0150] Except for the absence of a second coating, the rubber-reinforced cords of Examples 21 and 8 were obtained using the aqueous treatment agent with the composition shown in Table 6 as the first coating, and by the same method as in Examples 11-13 and Comparative Example 3. The obtained rubber-reinforced cords in... Figure 7 The cross-section of the reinforcing cord 70 shown has a cross-sectional structure without the second sheath 74. That is, the rubber reinforcing cords of Example 21 and Comparative Example 8 have the following cross-sectional structure: Figure 8 The cross-section shown.

[0151] (Example 22, Example 23, and Comparative Example 9)

[0152] The number of carbon fiber filaments bundled to make one filament bundle was changed to 6000. A water-based treatment agent with the composition shown in Table 7 was used as the first coating. During the twisting process, one filament was S-twisted or Z-twisted at a ratio of 80 twists / m (Example 22: S-twisting, Example 23 and Comparative Example 9: Z-twisting), and no second coating was formed. Otherwise, using the same method as Examples 1-10 and Comparative Example 1, rubber-reinforced cords of Examples 22, 23, and 9 were obtained. The resulting rubber-reinforced cords are reinforcing cords without a second coating and have the same characteristics as... Figure 1 The reinforcing cord shown has the same cross-section.

[0153] (Examples 24, 25, and Comparative Example 10)

[0154] The number of carbon fiber filaments bundled to make one filament bundle was changed to 3000. A water-based treatment agent with the composition shown in Table 8 was used as the first coating. During the twisting process, one filament was Z-twisted at a ratio of 120 twists / m, and no second coating was formed. Otherwise, using the same method as Examples 1-10 and Comparative Example 1, rubber-reinforced cords of Examples 24, 25, and 10 were obtained. The resulting rubber-reinforced cords are reinforcing cords without a second coating and have the same characteristics as... Figure 1 The reinforcing cord shown has the same cross-section.

[0155] (Examples 26, 27, and Comparative Example 11)

[0156] As the thread material disposed at the center, carbon fiber thread material with a first coating formed on the surface of a bundle composed of carbon fiber filaments was used. As the thread material disposed at the outer periphery of the carbon fiber thread material, glass fiber thread material with a first coating formed on the surface of a bundle composed of glass fiber filaments was used. The carbon fiber thread material was produced using the same method as the thread material produced in Examples 1-10 and Comparative Example 1. However, the water-based treatment agent used for the first coating was the treatment agent with the composition shown in Table 9, and the twisting direction was S-twist for Examples 23 and 27. The glass fiber thread material was obtained by bundling 600 K glass filaments (manufactured by Nippon Sheet Glass Co., Ltd.) with an average diameter of 7 μm to form a bundle, and forming a first coating on the surface of the bundle, the same as that of the carbon fiber thread material. Glass fiber thread material obtained by initial twisting 15 of the glass fiber thread material at a ratio of 80 twists / m was used. The drying conditions during the formation of the first coating were set in such a way that the liquid component content of the glass fiber thread material was the same as that of the carbon fiber thread material. One carbon fiber filament is positioned at the center, surrounded by 15 glass fiber filaments. It should be noted that a second coating is not formed. The resulting rubber-reinforced cord (the rubber-reinforced cords of Examples 26, 27, and Comparative Example 11) has the same characteristics as... Figure 3 The reinforcing cord shown has the same cross-section.

[0157] [Content of liquid components]

[0158] Within 30 minutes after heat treatment following the application of the first coating with an aqueous treatment agent, a 5m length of the resulting rubber-reinforced cord was collected as a sample. The sample was measured using an electronic balance, and this value was designated as the cord's mass A. The sample was then placed in a dryer heated to 150°C for 30 minutes to remove the solvent. The value measured using an electronic balance after 30 minutes in the dryer was designated as mass B. The difference between mass A and mass B was designated as the mass (AB) of the liquid component contained in the cord. The percentage of the liquid component (AB) contained in the cord relative to the cord's mass A ({(AB) / A}×100) was calculated and designated as the liquid component content (%). Tables 1 to 9 show the liquid component content of the rubber-reinforced cords in the examples and comparative examples.

[0159] [Tension test]

[0160] Tensile tests were conducted on the rubber-reinforced cords of each embodiment and comparative example using a conventional tensile testing machine and conventional cord clamps to determine the load at 0.8% elongation and the tensile strength. The tensile test conditions for the cords were: clamp spacing 250 mm, initial load 10 N, and tensile speed 300 mm / min. The maximum load was defined as the tensile strength, and the load at which the cord elongated by 0.8% (2 mm) was defined as the load at 0.8% elongation. The tensile modulus of elasticity of the rubber-reinforced cords of each embodiment and comparative example was evaluated using the load at 0.8% elongation. The results of the tensile tests on the rubber-reinforced cords of the embodiments and comparative examples are shown in Tables 1 to 9.

[0161] [Table 1]

[0162]

[0163] [Table 2]

[0164]

[0165] [Table 3]

[0166]

[0167] [Table 4]

[0168]

[0169] [Table 5]

[0170]

[0171] [Table 6]

[0172]

[0173] [Table 7]

[0174]

[0175] [Table 8]

[0176]

[0177] [Table 9]

[0178]

[0179] The liquid component content of the rubber-reinforced cords in Examples 1-27 is in the range of 0.2% by mass or more and 13% by mass or less. On the other hand, the liquid component content of the rubber-reinforced cords in Comparative Examples 1-11 is less than 0.2% by mass.

[0180] The tensile test results were compared between the examples and comparative examples with the same yarn composition. As shown in Table 1, the rubber reinforcing cords of Examples 1 to 10, which had a liquid component content of 0.2% by mass or more and 13% by mass or less, exhibited higher load and higher tensile modulus at 0.8% elongation compared to the rubber reinforcing cord of Comparative Example 1, which had a liquid component content of less than 0.2% by mass, and the rubber reinforcing cord of Comparative Example 2, which had a first coating formed by RFL treatment agent and a liquid component content of less than 0.2% by mass. Furthermore, the rubber reinforcing cords of Examples 1 to 10 possessed tensile strength equal to or greater than that of the rubber reinforcing cords of Comparative Examples 1 and 2. The rubber reinforcing cords of the examples and comparative examples shown in Tables 2 to 4 also yielded the same results as those shown in Table 1.

[0181] For Examples 18-27 and Comparative Examples 6-11, which did not have a second sheath, the tensile test results were also compared between the examples and comparative examples with the same yarn composition. As shown in Table 5, the rubber reinforcing cords of Examples 18-20, which had a liquid component content of 0.2% by mass or more and 13% by mass or less, exhibited a higher load at 0.8% elongation and a higher tensile modulus compared to the rubber reinforcing cord of Comparative Example 6, which had a liquid component content of less than 0.2% by mass, and the rubber reinforcing cord of Comparative Example 7, which had a first sheath formed by RFL treatment agent and a liquid component content of less than 0.2% by mass. Furthermore, the rubber reinforcing cords of Examples 18-20 had tensile strength equal to or greater than that of the rubber reinforcing cords of Comparative Examples 6 and 7. The rubber reinforcing cords of the examples and comparative examples shown in Tables 6-9 also showed the same results as those shown in Table 5.

[0182] Industrial availability

[0183] The rubber reinforcing cord of the present invention can achieve a high tensile modulus of elasticity, and therefore can be used to reinforce various rubber products. Furthermore, the rubber products of the present invention can withstand high loads, and therefore can be used for various applications.

Claims

1. A rubber-reinforced cord, It is used to reinforce rubber products. The rubber-reinforced cord has at least one strand. The yarn comprises at least one filament bundle and a first coating disposed in such a manner that it covers at least a portion of the surface of the filament bundle. The tow comprises carbon fiber filaments. The first membrane comprises a rubber component and a crosslinking agent. The rubber-reinforced cord further contains a liquid component. The liquid component in the rubber-reinforced cord is present in a concentration of 0.2% by mass or more and 13% by mass or less.

2. The rubber-reinforced cord according to claim 1, wherein, The liquid component in the rubber-reinforced cord is present in a concentration of 0.2% by mass or more and 5% by mass or less.

3. The rubber-reinforced cord according to claim 1, wherein, The rubber component comprises at least one selected from nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber.

4. The rubber-reinforced cord according to claim 1, wherein, The crosslinking agent comprises at least one selected from maleimide-based crosslinking agents and isocyanate compounds.

5. The rubber-reinforced cord according to claim 1, wherein, The first coating does not contain resorcinol-formaldehyde condensate.

6. The rubber-reinforced cord according to claim 1, wherein, The mass of the first coating is in the range of 5% to 35% relative to the mass of the filament bundle.

7. The rubber-reinforced cord according to claim 1, further comprising a second sheath disposed on the first sheath.

8. The rubber-reinforced cord according to claim 1, wherein, The thickness of the filament bundle is above 400 tex and below 3200 tex.

9. The rubber-reinforced cord according to claim 8, wherein, The thickness of the filament bundle is above 800 tex and below 1600 tex.

10. The rubber-reinforced cord according to claim 1, comprising carbon fiber strands as the cord material and a plurality of glass fiber strands disposed around the carbon fiber strands. The glass fiber filament comprises a bundle of glass fiber filaments containing glass fiber strands.

11. The rubber-reinforced cord according to claim 10, wherein, The total cross-sectional area of ​​the carbon fiber filament is in the range of 20% to 80% of the sum of the total cross-sectional area of ​​the carbon fiber filament and the total cross-sectional area of ​​the glass fiber filament.

12. A rubber article comprising: Matrix rubber, and The rubber-reinforced cord according to any one of claims 1 to 11.

13. The rubber product according to claim 12, wherein, The rubber-reinforcing cord is embedded in the matrix rubber.

14. The rubber article according to claim 12, wherein, The rubber product is a rubber belt.

15. A method for manufacturing rubber-reinforced cord, It is used to manufacture rubber-reinforced cords according to any one of claims 1 to 11. The manufacturing method includes: (a) To make at least one bundle of filaments by bundling together multiple filaments containing carbon fiber filaments; and (b) The yarn is made by forming a first coating in such a way that it covers at least a portion of the surface of the yarn bundle.

16. The method for manufacturing rubber-reinforced cord according to claim 15, wherein, In (b), after the first coating is formed in such a way that it covers at least a portion of the surface of the filament bundle, the filament bundle with the first coating is twisted to form the yarn.

17. The method for manufacturing rubber-reinforced cord according to claim 15, wherein, In (b), after the filament bundle is twisted, the first coating is formed in such a way that it covers at least a portion of the surface of the twisted filament bundle, thereby forming the yarn.

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