desulfurized rubber, rubber composition, rubber composition for tire, tire, hose, belt, track

Abstract

Provided is a devulcanized rubber from which a crosslinked rubber having excellent mechanical strength can be produced. The devulcanized rubber has a weight average molecular weight of greater than 260,000 and less than 600,000, and includes a rubber component A that is soluble in a solvent and a rubber component B that is insoluble in the solvent, wherein the content ratio of the rubber component B is less than 45 mass% of the total mass of the content a of the rubber component A and the content b of the rubber component B.

Description

Technical Field

[0001] This invention relates to desulfurized rubber, rubber compositions, rubber compositions for tires, tires, hoses, belts, and tracks. Background Technology

[0002] From the perspective of environmental and resource conservation, research has been conducted on regenerating cross-linked rubber and reusing it as new cross-linked rubber.

[0003] For example, PTL 1 discloses a regenerated rubber obtained by desulfurizing vulcanized rubber, wherein the ratio of sol to gel is 10-80%, the weight-average molecular weight (Mw) of the sol obtained by gel permeation chromatography (GPC) is in the range of 20,000-300,000, and the swelling degree of the gel is 3.0-20.0.

[0004] Reference List

[0005] Patent documents

[0006] PTL 1: JP2000-128901A Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, according to the desulfurization method described in PTL 1, the weight-average molecular weight of the desulfurized rubber actually manufactured in the examples is as high as 258,000, and further research is needed to obtain liquid hydrocarbons with high molecular weight.

[0009] The object of the present invention is to provide desulfurized rubber and rubber compositions capable of manufacturing crosslinked rubber with excellent mechanical strength, tire rubber compositions capable of manufacturing tires with excellent mechanical strength, and tires, hoses, belts and tracks with excellent mechanical strength, and the subject of the present invention is to achieve this object.

[0010] Solution for solving the problem

[0011] <1> A desulfurized rubber comprising: a solvent-soluble rubber component A with a weight-average molecular weight greater than 260,000 and less than 600,000; and a solvent-insoluble rubber component B, wherein the content of rubber component B is less than 45% of the total mass of the content a of rubber component A and the content b of rubber component B.

[0012] <2> according to <1> The desulfurized rubber, wherein the weight-average molecular weight of rubber component A is greater than 300,000 and less than 600,000.

[0013] <3> according to <1> or <2> The desulfurized rubber, wherein rubber component A and rubber component B comprise at least one selected from the group consisting of isoprene backbone, butadiene backbone and styrene-butadiene backbone.

[0014] <4> according to <1> to <3> The desulfurized rubber according to any one of the following methods, wherein the rubber component A and the rubber component B comprise an isoprene backbone.

[0015] <5> A rubber composition comprising a rubber component, wherein the amount of said rubber component contained therein is greater than 10% by mass according to [the specified formula / reference]. <1> to <4> The desulfurized rubber as described in any one of the following.

[0016] <6> according to <5> The rubber composition further comprises a filler, the amount of which is 20 to 120 parts by weight relative to 100 parts by weight of the rubber component.

[0017] <7> A rubber composition for tires, comprising according to <5> or <6> The rubber composition described above.

[0018] <8> A type of tire, the use of which is based on <7> The aforementioned rubber composition for tires.

[0019] <9> A type of hose, the use of which is based on <5> or <6> The rubber composition described above.

[0020] <10> A type of belt, the use of which is based on <5> or <6> The rubber composition described above.

[0021] <11> A type of track, the use of which is based on <5> or <6> The rubber composition described above.

[0022] The effects of the invention

[0023] According to the present invention, desulfurized rubber and rubber compositions capable of manufacturing crosslinked rubber with excellent mechanical strength, tire rubber compositions capable of manufacturing tires with excellent mechanical strength, and tires, hoses, belts and tracks with excellent mechanical strength can be provided. Detailed Implementation

[0024] <Desulfurized rubber>

[0025] The desulfurized rubber of the present invention comprises a solvent-soluble rubber component A with a weight-average molecular weight greater than 260,000 and less than 600,000 and a solvent-insoluble rubber component B, wherein the content ratio of rubber component B is less than 45% of the total mass of the content a of rubber component A and the content b of rubber component B.

[0026] The desulfurized rubber of the present invention is a desulfurized rubber component in which the sulfur crosslinking in the vulcanized rubber is broken, and is a recycled rubber that can be recycled from the vulcanized rubber, but does not include powdered rubber manufactured by powdering vulcanized rubber.

[0027] Desulfurized rubber obtained through processes such as thermal decomposition of vulcanized rubber typically contains undecomposed solid components in addition to the liquid products. In cases where waste tires are used as vulcanized rubber, the tires usually contain fillers, and therefore the solid components also include fillers.

[0028] For raw rubber before vulcanization, in the case of isoprene rubber (IR), the weight-average molecular weight (Mw) is typically around 1,200,000 and the number-average molecular weight (Mn) is around 400,000; and in the case of styrene-butadiene copolymer rubber (SBR), the weight-average molecular weight (Mw) is typically around 400,000 and the number-average molecular weight (Mn) is around 100,000. When the Mw and Mn of the liquid hydrocarbons contained in the liquid component are closer to these values, it means that a rubber with molecular chains close to the molecular chains of the raw rubber has been obtained.

[0029] In existing desulfurized rubbers, which contain liquid hydrocarbons, the rubber molecules tend to break into small fragments and the weight-average molecular weight tends to decrease during desulfurization. Therefore, even when they are crosslinked again to obtain crosslinked rubber, their mechanical strength hardly increases.

[0030] In contrast, the desulfurized rubber of the present invention has the above-described structure, and therefore can be used to manufacture a crosslinked rubber with excellent mechanical strength.

[0031] Rubber component A is a component obtained by desulfurization as a liquid hydrocarbon, and is a component that contributes to the re-crosslinking reaction in the re-crosslinking of desulfurized rubber. Rubber component A has a weight-average molecular weight greater than 260,000, and therefore can improve the mechanical strength of the crosslinked rubber obtained by re-crosslinking desulfurized rubber.

[0032] Rubber component B is a solid residue that has not been decomposed, and even when the desulfurized rubber is re-crosslinked, rubber component B hardly contributes to the re-crosslinking reaction. In the desulfurized rubber, the content of rubber component B is less than 45% of the total mass of rubber components A and B, and therefore the proportion of the active ingredient, namely rubber component A, can be large, and it is believed that this can produce crosslinked rubber with excellent mechanical strength.

[0033] The desulfurized rubber of the present invention will now be described in detail.

[0034] (Rubber component A)

[0035] Rubber component A is a solvent-soluble rubber component obtained by desulfurization of vulcanized rubber, and its weight-average molecular weight is greater than 260,000 and less than 600,000.

[0036] Rubber component A is soluble in solvent, meaning that when the component is placed at 25°C and atmospheric pressure (0.1 MPa) for 20 hours, its solubility in 100g of solvent is greater than 10g.

[0037] Here, a wide range of known solvents can be used as solvents, and examples include water; alcohol solvents such as methanol, ethanol, and 2-propanol; aliphatic or alicyclic hydrocarbon solvents such as hexane, cyclohexane, and heptane; aromatic hydrocarbon solvents such as benzene, chlorobenzene, toluene, and xylene; halogenated hydrocarbon solvents such as dichloromethane, 1,2-dichloroethane, chloroform, and carbon tetrachloride; ether solvents such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ester solvents such as methyl acetate and ethyl acetate; ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N-dimethylformamide; nitrile solvents such as acetonitrile and propionitrile; and aprotic polar solvents such as dimethyl sulfoxide, N-methylpyrrolidone, and N,N'-dimethylimidazolinone. These solvents can be used alone, or in combination of two or more as needed.

[0038] The solvents preferably include alcohol-based solvents and ether-based solvents, with ether-based solvents being more preferred.

[0039] When left overnight at 25°C and atmospheric pressure, the solubility of rubber component A in an ether-based solvent is preferably 3 g / 100 g or more, more preferably 4 g / 100 g or more, even more preferably 10 g / 100 g or more, even more preferably 20 g / 100 g or more, even more preferably 55 g / 100 g or more, and even more preferably 65 g / 100 g or more.

[0040] Rubber component A is a liquid hydrocarbon.

[0041] "Liquid" means that the substance can be in a liquid state at room temperature (25°C) and atmospheric pressure (0.1 MPa) or can be readily dissolved in petroleum components (e.g., alcohols, diethyl ether, tetrahydrofuran) to become liquid.

[0042] The weight-average molecular weight of component A is greater than 260,000 and less than 600,000.

[0043] When the weight-average molecular weight of component A is below 260,000, the mechanical strength of the re-crosslinked rubber obtained by re-crosslinking desulfurized rubber cannot be excellent, and if so, it is difficult to obtain a rubber component with a weight-average molecular weight of 600,000 or more as a soluble component of desulfurized rubber.

[0044] The weight-average molecular weight of rubber component A is preferably greater than 300,000 and less than 600,000, more preferably greater than 320,000, and even more preferably greater than 350,000.

[0045] The weight-average molecular weight of rubber component A can be measured, for example, by gel permeation chromatography (GPC).

[0046] (Rubber component B)

[0047] Rubber component B is a solvent-insoluble component of the rubber component obtained by desulfurization of vulcanized rubber, and it contributes almost nothing to the crosslinking reaction in the re-crosslinking of desulfurized rubber.

[0048] Rubber component B is insoluble in the solvent, which means that its solubility in 100g of solvent is less than 3g.

[0049] There are no particular restrictions on the type of solvent, and one or more of the solvents mentioned above may be used. Preferably, the solvents include alcohol-based solvents and ether-based solvents, and more preferably, ether-based solvents.

[0050] The solubility of rubber component B in ether-based solvents is preferably less than 3 g / 100 g, more preferably less than 2 g / 100 g, and even more preferably less than 1 g / 100 g.

[0051] The content of rubber component B in desulfurized rubber is less than 45% by mass of the total mass of rubber component A (a) and rubber component B (b). When the content of rubber component B in desulfurized rubber is 45% by mass or more, the content of rubber component A, which is the crosslinking component in the recrosslinking of desulfurized rubber, is low, and if so, the mechanical strength of the recrosslinked rubber decreases.

[0052] The content ratio of rubber component B in desulfurized rubber is preferably 40% by mass or less, more preferably 38% by mass or less, and even more preferably 35% by mass or less, of the total mass of rubber component A (a) and rubber component B (b). There is no particular limitation on the lower limit of the content ratio of rubber component B in desulfurized rubber, and it is generally 15% by mass or more of the total mass of rubber component A (a) and rubber component B (b).

[0053] The desulfurized rubber of the present invention can be a mixture of different soluble components (rubber component A) and insoluble components (rubber component B) of the desulfurization source, i.e., vulcanized rubber, but preferably a mixture of soluble components (rubber component A) and insoluble components (rubber component B) obtained by desulfurization of the same vulcanized rubber.

[0054] Therefore, rubber component A and rubber component B preferably both contain at least one selected from the group consisting of isoprene skeleton, butadiene skeleton and styrene-butadiene skeleton, and preferably contain isoprene skeleton.

[0055] <Manufacturing Method of Desulfurized Rubber>

[0056] As a first embodiment, the method for manufacturing desulfurized rubber of the present invention preferably includes the step of obtaining desulfurized rubber by heating the rubber in a reaction solvent containing an aldehyde having two or more hydrocarbon groups at a temperature below 300°C.

[0057] As a second embodiment, the manufacturing method preferably includes the step of obtaining desulfurized rubber by heating vulcanized rubber in a reaction solvent containing a compound at a temperature above 150°C and below 300°C, wherein the compound contains at least one aliphatic carbon-carbon double bond and wherein the number of hydroxyl and aldehyde groups is 0 each.

[0058] The steps for obtaining desulfurized rubber in the first and second embodiments can be referred to as the "decomposition steps" below.

[0059] In addition to the above-described decomposition steps, the method for manufacturing desulfurized rubber of the present invention may also include a drying step of drying the reaction products obtained in the decomposition steps.

[0060] The desulfurized rubber manufacturing method comprises the steps described above, and thus it is easy to obtain a liquid rubber component A with a weight-average molecular weight greater than 260,000, and the content ratio of the solvent-insoluble rubber component B can be easily less than 45% of the total mass of the content a of rubber component A and the content b of rubber component B.

[0061] The method for manufacturing desulfurized rubber of the present invention is effective for regenerating crosslinked rubber that has been crosslinked with a crosslinking agent other than a vulcanizing agent, and a rubber composition containing a liquid hydrocarbon corresponding to rubber component A can be obtained by heating the rubber in a reaction solvent containing an aldehyde having two or more carbon atoms at a temperature below 300°C, or by heating the rubber in a reaction solvent containing a compound having at least one aliphatic carbon-carbon double bond and wherein the number of hydroxyl and aldehyde groups is 0.

[0062] The rubber composition or desulfurized rubber obtained by decomposing the cross-linked structure of cross-linked rubber (including vulcanized rubber) in the above decomposition steps can be called an "organic decomposition product".

[0063] In the desulfurized rubber manufacturing method of the present invention, it is believed that the bonds (carbon-carbon bonds) originating from the carbon atoms of the rubber molecules constituting the vulcanized rubber, and the bonds (e.g., carbon-sulfur bonds) between the carbon atoms and heteroatoms (e.g., oxygen atoms, sulfur atoms) originating from the crosslinking agent can be broken by heating or by solvent effect to generate free radicals and / or new bonds.

[0064] It is also believed that hydrogen atoms released from aldehydes with two or more carbon atoms are attracted by highly reactive free radicals formed through bond breaking, thus halting the free radical reaction. Furthermore, it is believed that aldehydes with two or more carbon atoms are more likely to initiate hydrogen donation than alcohols, thereby more easily halting the free radical reaction and readily causing its cessation. In addition, primary aldehydes are oxidized to primary carboxylic acids by the oxygen required for the breaking of the rubber molecule's main chain, and thus oxygen in the autoclave can be consumed. As a result, it is believed that main chain breaking can be suppressed, and rubber component A, i.e., a liquid hydrocarbon with a higher molecular weight than usual, can be obtained.

[0065] [Vulcanized Rubber]

[0066] Vulcanized rubber is a sulfide of rubber components, and the rubber components (pure rubber components) used as raw materials for vulcanized rubber can be either diene rubber or non-diene rubber.

[0067] Diene-based rubbers include at least one selected from the group consisting of natural rubber (NR) and synthetic diene-based rubbers.

[0068] Examples of synthetic diene rubbers include polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, and acrylonitrile-butadiene rubber (NBR).

[0069] Examples of non-diene rubbers include butyl rubber, ethylene-propylene rubber, polyurethane rubber, silicone rubber, and acrylic rubber.

[0070] One of these rubber components can be used alone or in combination of two or more.

[0071] In the aforementioned rubbers, since diene rubbers are commonly used in rubber products such as tires, the rubber component preferably contains diene rubber in an amount of 50% by mass or more. Specifically, the crosslinked rubber is preferably a crosslinked product of a rubber component containing 50 to 100% by mass of diene rubber. More preferably, the rubber component contains diene rubber in an amount of 70% by mass or more, and even more preferably, it contains diene rubber in an amount of 90% by mass or more. It is also preferable that the diene rubber is at least one selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene, and styrene-butadiene copolymer rubber.

[0072] It is believed that by heating vulcanized rubber in a reaction solvent containing aldehydes with two or more carbon atoms below 300°C, the carbon-sulfur bonds that mainly constitute the molecular structure of vulcanized rubber can be broken by heating or exchanged through the solvent effect. Therefore, the hydrogen atoms released from aldehydes with two or more carbon atoms can be attracted by highly reactive free radicals formed through bond breaking to stop the free radical reaction.

[0073] When the above-described desulfurized rubber manufacturing method is applied to crosslinked rubber obtained using a crosslinking agent other than a vulcanizing agent, examples of crosslinking agents for the rubber components include organic peroxide-based crosslinking agents, acid crosslinking agents, polyamine crosslinking agents, resin crosslinking agents, and oxime-nitrosamine-based crosslinking agents.

[0074] (filler)

[0075] Vulcanized rubber may contain fillers.

[0076] Tires typically contain reinforcing fillers such as carbon black or silica to improve various tire functions, such as durability and wear resistance.

[0077] On the other hand, vulcanized rubber without fillers can increase the decomposition rate of rubber component A and suppress the content of rubber component B.

[0078] As a filler, either silica or carbon black can be used alone, or both silica and carbon black can be used simultaneously.

[0079] There are no particular limitations on silica; depending on the intended use, either ordinary grade silica or special silica surface-treated with a silane coupling agent can be used. For example, wet silica is preferred as the silica used.

[0080] There are no particular limitations on carbon black, and it can be appropriately selected according to the intended use. For example, FEF, SRF, HAF, ISAF, or SAF grades are preferred as carbon black.

[0081] The filler content in the vulcanized rubber is preferably 20 to 100 parts by weight, more preferably 30 to 90 parts by weight, relative to 100 parts by weight of the rubber component.

[0082] Vulcanized rubber can be a crosslinked product manufactured by crosslinking a rubber composition, which, in addition to the rubber components and the fillers described above, may, as needed, contain blending agents commonly used in the rubber industry, such as softeners, stearic acid, antioxidants, zinc oxide, and vulcanization accelerators. Tires typically comprise vulcanized rubber manufactured by vulcanizing a rubber composition containing these blending agents.

[0083] [Reaction Solvent]

[0084] An example of a reaction solvent is an embodiment containing an aldehyde (compound 1 in this invention) having two or more hydrocarbon groups having two or more carbon atoms.

[0085] Other examples include embodiments containing a compound (compound 2 in this invention) that comprises at least one aliphatic carbon-carbon double bond and wherein the number of hydroxyl and aldehyde groups is 0 each.

[0086] By selecting aldehydes with two or more carbon atoms or compounds containing at least one aliphatic carbon-carbon double bond with zero hydroxyl and zero aldehyde groups as the reaction solvent, the crosslinking points of vulcanized rubber can be decomposed while inhibiting the breaking of the rubber molecule's main chain, and the molecular weight of the rubber component A to be recovered can be maintained at a high level. This is believed to be because oxidative degradation may occur when alcohols are used as the reaction solvent, while aldehydes hardly cause oxidative degradation.

[0087] (Aldehydes having two or more hydrocarbon groups: Compound 1 in this invention)

[0088] When the number of carbon atoms in the hydrocarbon group of an aldehyde is less than 2, the molecular weight of the rubber component A to be recycled cannot be kept high.

[0089] From the viewpoint of maintaining a higher molecular weight of the rubber component A to be recycled, the hydrocarbon group preferably has 3 to 12, more preferably 6 to 10 carbon atoms.

[0090] There are no particular restrictions on the hydrocarbon groups that aldehydes can have, as long as they have two or more carbon atoms, and examples include aliphatic groups and aromatic groups.

[0091] Aliphatic groups can be linear or branched, and can be saturated or unsaturated aliphatic groups. Examples of aliphatic groups include ethyl, 1-propyl, 1-butyl, 2-butyl, tert-butyl, 1-pentyl, 2-methyl-1-pentyl, 1-hexyl, 1-heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-dodecyl; vinyl and propenyl.

[0092] Aromatic groups include phenyl and naphthyl groups.

[0093] One of the aldehydes having two or more hydrocarbon groups can be used alone or in combination of two or more. Besides having the aforementioned hydrocarbon groups, there are no particular restrictions; the aldehyde can have any other substituents, such as halogen atoms.

[0094] Specific examples of aldehydes having two or more hydrocarbon groups include aldehydes having a propyl group (propionaldehyde), aldehydes having a butyl group (butanaldehyde), aldehydes having a pentyl group (pentanaldehyde), aldehydes having a hexyl group (hexanal), aldehydes having a heptyl group (heptanaldehyde), aldehydes having an octyl group (octanaldehyde), aldehydes having a nonyl group (nonanaldehyde), aldehydes having a decyl group (decanaldehyde), aldehydes having an unsaturated carbon chain (cinnamaldehyde), and aldehydes having a phenyl group (benzaldehyde).

[0095] In the aforementioned aldehydes, from the viewpoint of maintaining a higher molecular weight of the rubber component A to be recycled, the hydrocarbon group is preferably an aliphatic group, more preferably a saturated aliphatic group, and even more preferably a linear saturated aliphatic group.

[0096] Specifically, the aldehyde having two or more hydrocarbon groups with carbon atoms is preferably at least one selected from the group consisting of hexyl aldehydes (hexanal), heptyl aldehydes (heptal), octyl aldehydes (octanal), and nonyl aldehydes (nonal), and more preferably nonyl aldehydes (nonal).

[0097] (A compound having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is 0 each: Compound 2 in this invention)

[0098] From the viewpoint of maintaining a higher molecular weight of the liquid hydrocarbon to be recovered and thus producing liquid hydrocarbons with a high decomposition rate, compounds having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is 0, preferably have 4 to 18 carbons, more preferably 4 to 16, even more preferably 5 to 14, further more preferably 5 to 12, and even more preferably 5 to 10.

[0099] Specifically, the compound includes anethole (10 carbon atoms), pinene (10 carbon atoms), artemisinin (10 carbon atoms), limonene (10 carbon atoms), carene (10 carbon atoms), camphene (10 carbon atoms), and their derivatives. The compound includes isomers (if any).

[0100] Derivatives of compounds 1 and 2 in this invention can also be used as reaction solvents.

[0101] Derivatives include those having a structure in which at least one hydrogen atom is substituted by a substituent such as an alkyl group. Alkyl groups include methyl, pentyl (propyl), butyl, and hexyl.

[0102] Specifically, examples of cinnamaldehyde derivatives include alkyl aldehydes, with pentylcinnamaldehyde (14 carbons) being particularly preferred. Compounds other than cinnamaldehyde, such as heptanal, anethole, and other derivatives, are also available.

[0103] The reaction solvent may consist of an aldehyde having two or more carbon atoms or a compound having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is zero. Alternatively, it may contain any other solvent besides an aldehyde having two or more carbon atoms or a compound having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is zero. However, from the viewpoint of improving the decomposition rate of rubber component A, it is preferable that any one of the aldehyde having two or more carbon atoms or a compound having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is zero, is the main component of the reaction solvent.

[0104] Here, "main component" means that, in the reaction solvent, the content of an aldehyde having two or more hydrocarbon groups or a compound having at least one aliphatic carbon-carbon double bond, wherein the number of hydroxyl and aldehyde groups is 0, is greater than 50% by volume, and the content of an aldehyde having two or more hydrocarbon groups in the reaction solvent is preferably 70% by volume or more, more preferably 90% by volume or more, and may be 100% by volume or more.

[0105] In the decomposition step, a reaction solvent is preferably used such that the ratio of the volume [mL] (Vs) of the reaction solvent to the mass [mg] (Wg) of the vulcanized rubber (Vs / Wg) can be in the range of 0.001 / 1 to 1 / 1, more preferably 0.005 / 1 to 0.1 / 1.

[0106] When the reaction solvent is used within the above range, the solvent decomposition reaction can be further accelerated, and sufficient hydrogen atoms can be provided to the vulcanized rubber to prevent the recombination of free radicals formed by thermal decomposition, and thus the vulcanized rubber can be effectively decomposed.

[0107] [Reaction conditions in the decomposition step]

[0108] (temperature)

[0109] In the decomposition step, in the first embodiment, the vulcanized rubber and the reaction solvent are heated to below 300°C, and in the second embodiment, the vulcanized rubber and the reaction solvent are heated to above 150°C and below 300°C.

[0110] When the heating temperature is below 300°C, this step can be excellent in terms of energy saving and can suppress the decrease in decomposition rate caused by side reactions, etc. The heating temperature in the decomposition step can be called the decomposition temperature. By heating the vulcanized rubber at a lower temperature, the solvent-implicated reaction can preferentially proceed to decompose the vulcanized rubber. The heating temperature is preferably above 150°C, more preferably above 155°C, even more preferably above 160°C, and also preferably below 250°C, more preferably below 240°C, even more preferably below 230°C, further preferably below 220°C, and even more preferably below 210°C.

[0111] (Time Breakdown)

[0112] In the decomposition step, from the viewpoint of fully promoting the decomposition reaction of vulcanized rubber, the heating time (decomposition time) of vulcanized rubber is preferably 30 minutes to 20 hours, more preferably 60 minutes to 180 minutes.

[0113] (pressure)

[0114] There are no particular restrictions on the pressure applied to the vulcanized rubber and the reaction solvent during the decomposition step.

[0115] From the viewpoints of reaction rate, resource conservation, and energy saving in the decomposition reaction of vulcanized rubber, the pressure is preferably 0.1 to 2.0 MPa(G), more preferably 0.1 to 1.5 MPa(G). The unit "MPa(G)" indicates that the pressure is gauge pressure.

[0116] When the pressure is below 2.0 MPa(G), the molecular weight of rubber component A hardly decreases, and when the pressure is above 0.1 MPa(G), the reaction solvent can easily penetrate into the vulcanized rubber, thereby easily increasing the reaction rate.

[0117] (atmosphere)

[0118] There are no particular restrictions on the reaction atmosphere in the decomposition step below 300°C, and the reaction can be carried out in an inert gas vapor atmosphere such as argon or nitrogen (hereinafter referred to as an inert gas atmosphere), or in an air vapor atmosphere (hereinafter referred to as an air atmosphere), or in a mixed gas atmosphere of air and inert gases. When using inert gases, two or more inert gases can be used in combination.

[0119] From the viewpoint of promoting energy conservation by decomposing vulcanized rubber in simpler equipment, vulcanized rubber is preferably heated in an oxygen-containing atmosphere, that is, in an oxygen-containing atmosphere, more preferably in an air-containing gas atmosphere, and even more preferably in an air atmosphere.

[0120] [Drying Steps]

[0121] The desulfurized rubber manufacturing method of the present invention preferably includes a drying step of drying the reaction product (the desulfurized rubber of the present invention) obtained in the decomposition step.

[0122] Hot air can be sprayed onto the reaction products at a temperature of, for example, 100–150°C. The hot air can be air or an inert gas such as nitrogen.

[0123] <Rubber Composition>

[0124] The rubber composition of the present invention comprises a rubber component, and the amount contained in the rubber component is greater than 10% by mass of the desulfurized rubber of the present invention.

[0125] The rubber composition of the present invention comprises a rubber component, wherein the rubber component is contained in an amount greater than 10% by mass of the desulfurized rubber of the present invention, and thus can produce a recrosslinked rubber with excellent mechanical strength while reducing environmental burden.

[0126] The rubber component may consist solely of the desulfurized rubber of the present invention, or it may contain a rubber component (pure rubber component) that is typically used as a raw material for vulcanized rubber.

[0127] The rubber compositions of the present invention may contain various additives, such as fillers and crosslinking agents typically found in rubber compositions.

[0128] From the viewpoint of reducing environmental burden, the content of the desulfurized rubber of the present invention in the rubber component is preferably greater, and can be 100% by mass.

[0129] From the viewpoint of not impairing the mechanical strength of the recrosslinked rubber obtained by recrosslinking the rubber composition, the content of the desulfurized rubber of the present invention in the rubber component is preferably 70% by mass or less.

[0130] From the viewpoint of reducing environmental burden and ensuring the mechanical strength of the re-crosslinked rubber, the content of the desulfurized rubber of the present invention in the rubber component is preferably 10-70% by mass, more preferably 11-68% by mass, even more preferably 12-65% by mass, further more preferably 13-62% by mass, further more preferably 15-60% by mass, further more preferably 17-58% by mass, further more preferably 19-54% by mass, and further more preferably 20-52% by mass.

[0131] Other rubber components used with the desulfurized rubber of the present invention include rubber components (pure rubber components) that are commonly used as raw materials for vulcanized rubber.

[0132] The pure rubber component is the aforementioned rubber component that serves as a raw material for crosslinked rubber. Preferably, it is selected from at least one of the group consisting of natural rubber (NR) and synthetic diene rubber, and more preferably, it is selected from at least one of the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber.

[0133] The rubber composition of the present invention may contain fillers.

[0134] When the rubber composition of the present invention contains fillers, it can improve various properties of the recrosslinked rubber, such as durability and abrasion resistance.

[0135] Fillers include reinforcing fillers such as carbon black and silica. Either silica or carbon black can be used alone, or both can be used together.

[0136] There are no particular limitations on silica; depending on the intended use, either ordinary grade silica or special silica surface-treated with a silane coupling agent can be used. For example, wet silica is preferred as the silica used.

[0137] There are no particular limitations on carbon black, and it can be appropriately selected according to the intended use. For example, FEF, SRF, HAF, ISAF, or SAF grades are preferred as carbon black.

[0138] The filler content in the vulcanized rubber is preferably 20 to 120 parts by weight, more preferably 30 to 100 parts by weight, and even more preferably 40 to 80 parts by weight, relative to 100 parts by weight of the rubber component.

[0139] In addition to the rubber components and fillers comprising the desulfurized rubber of the present invention, the rubber composition may also contain a crosslinking agent, a crosslinking accelerator, a softener, stearic acid, an antioxidant, and zinc oxide.

[0140] There are no particular limitations on the re-crosslinking conditions of the rubber composition of the present invention.

[0141] As a crosslinking agent, sulfur or other vulcanizing agents can be used, or organic peroxide crosslinking agents, acid crosslinking agents, polyamine crosslinking agents, resin crosslinking agents, or oxime-nitrosamine crosslinking agents can also be used.

[0142] When a vulcanizing agent is used as a crosslinking agent, one or more vulcanization accelerators can be used, such as sulfenamide, thiazole or guanidine vulcanization accelerators.

[0143] The rubber composition of the present invention can produce re-crosslinked rubber with excellent mechanical strength and reduced environmental impact, and is therefore beneficial for manufacturing industrial products such as vehicle components other than tires, hoses, pipes, vibration damping rubbers, conveyor belts, tracks, cables, sealing materials, marine components, and building materials.

[0144] <Rubber Compositions for Tires>

[0145] The rubber composition for tires of the present invention comprises the rubber composition of the present invention.

[0146] The rubber composition for tires of the present invention comprises the rubber composition of the present invention, and thus can be used to manufacture tires with excellent mechanical strength while reducing environmental impact.

[0147] <Tires>

[0148] The tire of the present invention is formed from the tire rubber composition of the present invention.

[0149] Using the rubber composition of the present invention, which includes the desulfurized rubber of the present invention, tires with excellent mechanical strength and reduced environmental burden can be manufactured.

[0150] For tires, uncrosslinked rubber compositions can be crosslinked after molding into a tire, depending on the type of tire and the components to be attached to it, or through a pre-crosslinking step, once a semi-crosslinked rubber is made from the uncrosslinked rubber composition and molded, it is then finally crosslinked to obtain the desired tire. Vapors to be filled into the tire include ordinary air or air with a controlled oxygen partial pressure, as well as inert gases such as nitrogen, argon, and helium.

[0151] <Hose, belt, track>

[0152] The hose of the present invention is formed from the rubber composition of the present invention.

[0153] The belt of the present invention is formed from the rubber composition of the present invention.

[0154] The track of the present invention is formed from the rubber composition of the present invention.

[0155] Using the rubber composition of the present invention to manufacture hoses, belts and tracks, it is possible to produce articles with excellent mechanical strength and reduced environmental impact.

[0156] Example

[0157] The present invention will now be described in more detail with reference to the embodiments given below. These embodiments are for illustrative purposes only and are not intended to limit the invention.

[0158] <Preparation of vulcanized rubber>

[0159] Prepare the following vulcanized rubber.

[0160] Vulcanized rubber (IR): Vulcanized rubber obtained by vulcanizing polyisoprene rubber.

[0161] Vulcanized rubber (a1): Vulcanized rubber obtained by vulcanizing a rubber composition containing at least natural rubber and carbon black.

[0162] Vulcanized rubber (a2): Vulcanized rubber obtained by vulcanizing a rubber composition containing at least natural rubber, polybutadiene rubber and carbon black.

[0163] <Desulfurized Rubber Manufacturing A>

[0164] [Example 1]

[0165] (Steps Breakdown)

[0166] 0.4 g of small flakes of vulcanized rubber (IR) with a size of approximately 1 mm and 5 mL of 1-heptanal were placed in an autoclave (manufactured by EYELA Corporation, pressure vessel, trade name "HIP-30L"). The autoclave was sealed and placed in a heating container (manufactured by EYELA Corporation, Personal Organic Synthesizer Chemistation, trade name "PPV-CTRL1"), and the contents of the autoclave were heated in air at 200°C for 2 hours. After heating, the heating container was cooled to room temperature (25°C) with cooling water, and the reaction product was allowed to remain at room temperature.

[0167] (Drying step)

[0168] The reaction product obtained in the decomposition step was dried in a nitrogen stream at 130°C using a spray-type tube concentrator (manufactured by EYELA Corporation, trade name "MGS-3100") to obtain the organic decomposition product (desulfurized rubber) of Example 1.

[0169] [Examples 2-5, Comparative Examples 1-2]

[0170] Except for changing the reaction solvent to the solvents shown in Table 1, the organic decomposition products (desulfurized rubber) of Examples 2-5 and Comparative Examples 1-2 were produced in the same manner as in Example 1 by means of decomposition and drying steps.

[0171] Analysis of Organic Decomposition Products (Desulfurized Rubber)

[0172] In the desulfurized rubber obtained in the examples and comparative examples, the liquid product (rubber component A) was dissolved in tetrahydrofuran and analyzed by gel permeation chromatography (GPC). Based on the analytical results, the proportion of solid components (rubber component B) and the weight-average molecular weight (Mw) of the liquid product (rubber component A) in the desulfurized rubber were determined.

[0173] In addition, calibration curves were plotted using tetrahydrofuran solutions of pure rubber component (IR) with different concentrations. Using these calibration curves, the liquid product (rubber component A) in tetrahydrofuran was quantified, and the decomposition rate of the liquid product (rubber component A) was calculated. The proportion of the solid component (rubber component B) in the desulfurized rubber was calculated as "100% - decomposition rate of the liquid product (rubber component A)".

[0174] The results are shown in Table 1. The significant figures in Table 1 are three digits.

[0175] The molecular weights shown in Table 1, for example in Example 1, are 389 × 10⁻⁶. 3 That is, 389,000.

[0176] The conditions for GPC measurements are as follows.

[0177] Pillar: TSK gel GMHXL, manufactured by Tosoh Corporation

[0178] Eluent: Tetrahydrofuran

[0179] Flow rate: 1 mL / min

[0180] Temperature: 40℃

[0181] Detector: RI

[0182] Table 1

[0183]

[0184] <Desulfurized rubber manufacturing B and re-vulcanized rubber manufacturing>

[0185] [Example 6]

[0186] Except for changing the vulcanized rubber (IR) to vulcanized rubber (a1) and changing the heating time (decomposition time) of the contents from 2 hours to the time shown in Table 2, the decomposition steps were performed in the same manner as in Example 3. Subsequently, purification was carried out to remove the solvent, and the organic decomposition product (desulfurized rubber A) of Example 6 was produced by a drying step.

[0187] The desulfurized rubber A thus produced was blended with the constituent components in the formulations shown in Table 3 to prepare the rubber compositions of Examples 7 and 8. Two rubber compositions were thus produced, wherein the content of desulfurized rubber A in the rubber component was 30 parts by mass or 70 parts by mass relative to 100 parts by mass of pure rubber component, i.e., polyisoprene rubber. The resulting rubber compositions were vulcanized separately to obtain revulcanized rubber.

[0188] [Comparative Example 3]

[0189] Except for changing the vulcanized rubber (IR) to vulcanized rubber (a1) and changing the heating time (decomposition time) of the contents from 2 hours to the time shown in Table 2, the decomposition steps were performed in the same manner as in Example 3. Subsequently, purification was carried out to remove the solvent, and the organic decomposition product (desulfurized rubber B) of Comparative Example 3 was produced by a drying step.

[0190] The desulfurized rubber B thus produced was blended with the constituent components in the formulations shown in Table 3 to prepare the rubber compositions of Comparative Examples 6 and 7. Two rubber compositions were thus produced, wherein the content of desulfurized rubber B in the rubber component was 30 parts by mass or 70 parts by mass relative to 100 parts by mass of pure rubber component, i.e., polyisoprene rubber. The resulting rubber compositions were vulcanized separately to obtain revulcanized rubber.

[0191] [Comparative Example 4]

[0192] Except for changing the vulcanized rubber (IR) to vulcanized rubber (a1) and changing the heating time (decomposition time) of the contents from 2 hours to the time shown in Table 2, the decomposition steps were performed in the same manner as in Example 3. Subsequently, purification was performed to remove the solvent, and the organic decomposition product (desulfurized rubber C) of Comparative Example 4 was produced by a drying step.

[0193] The desulfurized rubber C thus produced was blended with the constituent components in the formulations shown in Table 3 to prepare rubber compositions for Comparative Examples 8 and 9. Two rubber compositions were thus produced, wherein the content of desulfurized rubber C in the rubber component was 30 parts by mass or 70 parts by mass relative to 100 parts by mass of pure rubber component, i.e., polyisoprene rubber. The resulting rubber compositions were vulcanized separately to obtain revulcanized rubber.

[0194] [Comparative Example 5]

[0195] Except that 100% by mass of pure rubber component, namely polyisoprene rubber (IR), was used as the rubber component, the re-vulcanized rubber of Comparative Example 5 was manufactured in the same manner as the vulcanized rubber of Example 6.

[0196] The details of the components shown in Table 3 are as follows.

[0197] Desulfurized rubbers A-C: Desulfurized rubbers manufactured in Example 6, Comparative Example 3, and Comparative Example 4

[0198] IR: Polyisoprene rubber, manufactured by JSR Corporation, trade name "IR2200"

[0199] Carbon black: SAF grade

[0200] 6C: Antioxidant, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., trade name "Noclak 6C".

[0201] DM: Vulcanization accelerator, di-2-benzothiazole disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sanceler DM".

[0202] NS: Vulcanization accelerator, N-tert-butyl-2-benzothiazole sulfenamide, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., trade name "Nocceler NS"

[0203] DPG: Vulcanization accelerator, 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sanceler D".

[0204] Analysis of Desulfurized Rubber

[0205] The manufactured desulfurized rubbers A to C were analyzed using the same method as in Example 1 to determine the weight-average molecular weight (Mw) of the liquid product (rubber component A) and the proportion of solid components (rubber component B) in the desulfurized rubber, as shown in Table 2. The molecular weights and proportions of rubber component B in Table 2 are represented by three significant figures.

[0206] Similar to Table 1, the molecular weights shown in Table 2 are, for example, 271 × 10⁻⁶ in the case of Example 6. 3 That is, 271,000.

[0207] Table 2

[0208]

[0209] <Characteristic Evaluation of Vulcanized Rubber>

[0210] The mechanical strength and loss tangent (tanδ) of the recured rubbers of Examples 7-8, the reference recured rubber (the recured rubber of Comparative Example 5), and the recured rubbers of Comparative Examples 6-9 were evaluated. The results are shown in Table 3.

[0211] 1. Mechanical strength

[0212] The mechanical strength of each recured rubber is evaluated from the viewpoint of tensile strength at break (TB). To measure the tensile strength at break, the vulcanized rubber is elongated by 100% at room temperature (23°C) in accordance with JIS K 6251 (2017), and the maximum tensile force required to break is measured.

[0213] The resulting tensile strength at break is exponentialized by setting the value of the benchmark vulcanized rubber at break to 100. A larger exponent value means that the re-vulcanized rubber has a greater tensile strength at break.

[0214] 2. Loss tangent (tanδ)

[0215] The loss tangent (tanδ) of recured rubber was measured using a viscoelastic measuring device (ARES-G2, manufactured by TA Instruments Corporation) at 50°C, 10% strain, and 15Hz frequency. The resulting tanδ value was exponentialized by setting the reciprocal of the tanδ of the reference recured rubber to 100. A larger exponent value indicates better low-heat properties of the recured rubber.

[0216] Table 3

[0217]

[0218] <Desulfurized Rubber Manufacturing C>

[0219] [Example 9]

[0220] 0.4 g of small flakes of vulcanized rubber (IR) approximately 1 mm in size and 5 mL of anethole were placed in an autoclave (manufactured by EYELA Corporation, pressure vessel, trade name "HIP-30L"). The autoclave was sealed and placed in a heating container (manufactured by EYELA Corporation, Personal Organic Synthesizer Chemistation, trade name "PPV-CTRL1"), and the contents of the autoclave were heated in air at 200°C for 2 hours. After heating, the heating container was cooled to room temperature (25°C) with cooling water, and the reaction product was allowed to remain at room temperature.

[0221] (Drying step)

[0222] The reaction product obtained in the decomposition step was dried in a nitrogen stream at 130°C using a spray-type tube concentrator (manufactured by EYELA Corporation, trade name "MGS-3100") to obtain the organic decomposition product (desulfurized rubber D) of Example 9.

[0223] [Example 10, Example 11]

[0224] Except that the reaction solvent was changed to the reaction solvent shown in Table 4, the organic decomposition product of Example 10 (desulfurized rubber E) and the organic decomposition product of Example 11 (desulfurized rubber F) were produced in the same manner as in Example 9 by means of decomposition and drying steps.

[0225] Analysis of Organic Decomposition Products

[0226] The organic decomposition products obtained in Examples 9-11 were dissolved in tetrahydrofuran and analyzed by gel permeation chromatography (GPC). Based on the analytical results, the solubilization ratio and weight-average molecular weight (Mw) of the organic decomposition products were determined. Furthermore, calibration curves were plotted using tetrahydrofuran solutions of pure rubber components at different concentrations. Using the calibration curves, the liquid product (rubber component A) in tetrahydrofuran was quantified, and the decomposition rate of the liquid product (rubber component A) was calculated. The proportion of the solid component (rubber component B) in the desulfurized rubber was calculated as "100% - decomposition rate of the liquid product (rubber component A)".

[0227] The molecular weights shown in Table 4, for example in Example 9 (decomposition temperature 200°C), are 430 × 10⁻⁶. 3 That is, 430,000.

[0228] The conditions for GPC measurements are as follows.

[0229] Pillar: TSK gel GMHXL, manufactured by Tosoh Corporation

[0230] Eluent: Tetrahydrofuran

[0231] Flow rate: 1 mL / min

[0232] Temperature: 40℃

[0233] Detector: RI

[0234] Table 4

[0235]

[0236] <Desulfurized rubber manufacturing and re-vulcanized rubber manufacturing>

[0237] [Example 12, Comparative Example 10]

[0238] Except for changing the vulcanized rubber (IR) to vulcanized rubber (a2), changing the anethole to the solvent shown in Table 5, and changing the heating time (decomposition time) of the vulcanized rubber and solvent to the times shown in Table 5, the decomposition steps were performed in the same manner as the decomposition steps of Example 9. Subsequently, purification was performed to remove the solvent, and the organic decomposition product of Example 12 (desulfurized rubber G) and the organic decomposition product of Comparative Example 10 (desulfurized rubber H) were produced by a drying step.

[0239] Analysis of Organic Decomposition Products

[0240] The prepared organic decomposition products were analyzed in the same manner as those in Example 1 to measure the weight-average molecular weight (Mw) and decomposition rate of rubber component A. The proportion of rubber component B was calculated from the decomposition rate of rubber component A. The weight-average molecular weight of rubber component A and the proportion of rubber component B are shown in Table 5 with three significant figures.

[0241] The molecular weights shown in Table 5, for example in Example 12, are 300 × 10⁻⁶. 3 That is, 300,000.

[0242] Table 5

[0243]

[0244] In all desulfurized rubbers A to H manufactured in the examples and comparative examples, when the rubber component A was left to stand for 20 hours at 25°C and atmospheric pressure (0.1 MPa), the solubility of rubber component A in 100 g of diethyl ether was more than 3 g, and when the rubber component B was left to stand for 20 hours at 25°C and atmospheric pressure (0.1 MPa), the solubility of rubber component B in 100 g of diethyl ether was less than 0.1 g.

[0245] The desulfurized rubbers G and H thus produced were blended with the constituent components in the formulations shown in Table 6 to prepare rubber compositions of Comparative Examples 11-12 and Examples 13-15. The resulting rubber compositions were vulcanized to obtain re-vulcanized rubber.

[0246] The details of the components shown in Table 6 are as follows.

[0247] NR: Natural Rubber

[0248] BR: High cis-polybutadiene, manufactured by UBE Corporation, trade name "UBEPOL BR150L"

[0249] Carbon black: SAF grade

[0250] Antioxidant: An antioxidant containing "Noclak 6C" (trade name), manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0251] Vulcanized package: Contains sulfur.

[0252] In addition to the components shown in Table 6, the rubber compositions of Comparative Examples 11-12 and Examples 13-15 also contain a total of 7.9 parts by weight of other chemical substances.

[0253] <Property Evaluation of Vulcanized Rubber>

[0254] The mechanical strength of the recured rubbers from Comparative Examples 11-12 and Examples 13-15 was evaluated. The results are shown in the table.

[0255] 1. Mechanical strength

[0256] The mechanical strength of each recured rubber is evaluated from the viewpoint of tensile strength at break (TB). To measure the tensile strength at break, the vulcanized rubber is elongated by 100% at room temperature (23°C) in accordance with JIS K 6251 (2017), and the maximum tensile force required to break is measured.

[0257] The resulting tensile strength at break is exponentialized by setting the value of the benchmark vulcanized rubber at break to 100. A larger exponent value means that the re-vulcanized rubber has a greater tensile strength at break.

[0258] Table 6

[0259]

[0260] As shown in Table 1, in Examples 1-5, the content ratio of rubber component B (i.e., the solid component) is lower than that in Comparative Examples 1 and 2, and desulfurized rubber containing liquid hydrocarbons (rubber component A) with a higher molecular weight can be produced. Similarly, it is also known that in Examples 9-11 shown in Table 4, the content ratio of rubber component B (i.e., the solid component) is even smaller, and desulfurized rubber containing liquid hydrocarbons (rubber component A) with a high molecular weight can be produced.

[0261] As can be seen from Tables 2 and 3, the recurved rubber manufactured from the rubber composition containing desulfurized rubber A of Example 6 has greater mechanical strength than the recurved rubber manufactured from the rubber composition containing desulfurized rubber B or C of Comparative Examples 3 and 4, and has lower heat generation. Furthermore, it is known that the recurved rubber manufactured from the rubber composition containing desulfurized rubber A of Example 6 has the same mechanical strength and low heat generation as the reference recurved rubber containing pure rubber components. Similarly, it is known that when comparing Example 15 and Comparative Example 12 with reference to Tables 5 and 6, the recurved rubber manufactured from the rubber composition containing desulfurized rubber G of Example 12 has greater mechanical strength.

Claims

1. A desulfurized rubber, comprising: Rubber component A, which is soluble in solvents and has a weight-average molecular weight greater than 260,000 and less than 600,000; and Rubber component B, which is insoluble in solvents The content of rubber component B is less than 45% by mass of the total mass of rubber component A (content a) and rubber component B (content b). Rubber component A is soluble in a solvent, meaning that when the component is placed at 25°C and atmospheric pressure of 0.1 MPa for 20 hours, its solubility in 100g of solvent is greater than 10g; rubber component B is insoluble in a solvent, meaning that its solubility in 100g of solvent is less than 3g; the solvent includes ether-based solvents; rubber component A is a liquid hydrocarbon, and rubber components A and B comprise at least one component selected from the group consisting of isoprene backbone, butadiene backbone, and styrene-butadiene backbone.

2. The desulfurized rubber according to claim 1, wherein the weight-average molecular weight of rubber component A is greater than 300,000 and less than 600,000.

3. The desulfurized rubber according to claim 1 or 2, wherein the rubber component A and the rubber component B comprise an isoprene backbone.

4. A rubber composition comprising a rubber component, and The amount of the desulfurized rubber according to claim 1 or 2 in the rubber component is greater than 10% by mass.

5. The rubber composition according to claim 4, further comprising a filler, said filler being in an amount of 20 to 120 parts by weight relative to 100 parts by weight of said rubber component.

6. A rubber composition for tires comprising the rubber composition according to claim 4.

7. A tire that uses the tire rubber composition according to claim 6.

8. A hose that uses the rubber composition according to claim 4.

9. A belt using the rubber composition according to claim 4.

10. A track that uses the rubber composition according to claim 4.

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