Tire

Abstract

To provide a tire that improves overall performance of abrasion resistance performance and ride comfort performance.SOLUTION: There is provided a tire having a tread part, the tread part is constituted of a rubber composition containing a rubber component, carbon black and rubber powder, where in the case where the content of carbon black for the rubber component 100 pts.mass of the rubber composition is C (pts.mass), C is more than 20, the rubber powder contains a sulfur element, in the case where the particle diameter of rubber powder is 40 mesh or more and the BET specific surface area of rubber powder is B(m2 / g), B is 0.100 or more, when the thickness of the tread part is T(mm), T is 3.0 or more, in the case where the content of rubber powder for the rubber component 100 pts.mass of the rubber composition is A(pts.mass), A / T is less than 20, and in the case where the BET specific surface area of carbon black is E(m2 / g), (C×E) / (A×B) is more than 1000.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a tire. [Background technology]

[0002] Various methods for improving the wear resistance and ride comfort of tires have been studied. For example, Patent Document 1 describes that a rubber composition for tires containing a predetermined amount of rubber component, in which the total amount of styrene in the rubber component is less than 20 mass %, and in which the contents of silica, butadiene rubber, and resin are in a predetermined relationship, can improve wear resistance during high-speed running. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-71373 Summary of the Invention [Problem to be solved by the invention]

[0004] There is room for further improvement in the overall performance of wear resistance and ride comfort.

[0005] An object of the present invention is to provide a tire that improves the overall performance of wear resistance and ride comfort. [Means for solving the problem]

[0006] The present invention provides A tire having a tread portion, the tread portion is made of a rubber composition containing a rubber component, carbon black, and rubber powder, When the content of carbon black per 100 parts by mass of the rubber component of the rubber composition is C (parts by mass), C is more than 20, The rubber crumb contains elemental sulfur, The particle size of the rubber powder is 40 mesh or more, The BET specific surface area of ​​the rubber powder is defined as B (m 2 / g), B is 0.100 or more, When the thickness of the tread portion is T (mm), T is 3.0 or more, When the content of rubber powder relative to 100 parts by mass of the rubber component of the rubber composition is A (parts by mass), A / T is less than 20, The BET specific surface area of ​​the carbon black is defined as E (m 2 / g), (C×E) / (A×B) is greater than 1000. [Effects of the Invention]

[0007] According to the present invention, a tire is provided which improves the overall performance of wear resistance and ride comfort. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a portion of a tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a tire according to one embodiment of the present invention will be described. The tire according to this embodiment has a tread portion, and the tread portion is made of a rubber composition containing a rubber component, carbon black, and rubber crumb, and when the content of carbon black per 100 parts by mass of the rubber component of the rubber composition is C (parts by mass), C is greater than 20, the rubber crumb contains sulfur element, the particle size of the rubber crumb is 40 mesh or more, and the BET specific surface area of ​​the rubber crumb is B (m 2 / g), B is 0.100 or more, and when the thickness of the tread portion is T (mm), T is 3.0 or more, and when the content of rubber powder per 100 parts by mass of the rubber component of the rubber composition is A (parts by mass), A / T is less than 20, and the BET specific surface area of ​​the carbon black is E (m 2 / g), (C×E) / (A×B) is greater than 1000.

[0010] Although not intending to be bound by theory, the reason why the present invention provides a tire that improves the overall performance of wear resistance and ride comfort is thought to be, for example, as follows.

[0011] First, (1) the rubber composition constituting the tread portion contains a rubber component and rubber crumb, and the rubber crumb contains sulfur, which crosslinks the rubber crumb and the rubber component, contributing to improving the reinforcing properties of the rubber composition. (2) The particle size of the rubber crumb is 40 mesh or more, and the BET specific surface area is 0.100 m. 2 / g or more, the reinforcing effect of the rubber crumb is further improved. In addition, (3) having the carbon black content C exceed 20 parts by mass contributes to improved wear resistance. (4) Having a tread thickness T of 3.0 mm or more allows the tread surface to absorb impact from the road surface, contributing to improved ride comfort of the tire. (5) Having an A / T ratio of less than 20 and a small rubber crumb content A relative to the tread thickness T prevents stress concentration on the tread surface and contributes to improved reinforcing effect of the tread portion on the radially inner side of the tire. Furthermore, (6) having (C × E) / (A × B) exceed 1,000 allows carbon black to be placed in the gaps between the rubber crumbs in an amount and particle size that is sufficient to reinforce the rubber component, contributing to improved reinforcing effect.

[0012] It is believed that the cooperation of the above (1) to (6) achieves the remarkable effect of providing a tire that improves the overall performance of wear resistance and ride comfort.

[0013] The A / T is preferably less than 10.

[0014] This is because a reinforcing effect is also produced on the radially inner side of the tread portion of the tire, which is thought to further improve wear resistance.

[0015] The (C×E) / (A×B) ratio is preferably greater than 2,000.

[0016] This is because it is believed that the reinforcing effect of the rubber composition constituting the tread portion is further enhanced, and the wear resistance performance is further improved.

[0017] With respect to C and T, C×T is preferably greater than 100.

[0018] When the carbon black content is low, it is believed that by increasing the thickness of the tread portion, the reinforcement of the tread portion is ensured, and the wear resistance performance is further improved.

[0019] The E(m 2 / g) is preferably greater than 100.

[0020] It is believed that by increasing the BET specific surface area of ​​the carbon black, the carbon black can further reinforce the rubber component in the gaps between the rubber powder, further improving abrasion resistance.

[0021] The rubber component preferably contains 30% by mass or more of isoprene-based rubber.

[0022] It is believed that by ensuring that the content of the isoprene-based rubber is within the above range, the breaking strength of the rubber composition can be increased, and the abrasion resistance performance can be further improved.

[0023] From the viewpoint of further improving the abrasion resistance, the rubber component preferably contains 50% by mass or more of butadiene rubber.

[0024] [Definition] The "tread portion" refers to a component that includes the portion that forms the tire's contact surface, and in the case where the tire is provided with components that form the tire skeleton from steel or textile materials, such as a belt layer, a belt reinforcing layer, and a carcass, the "tread portion" is a component that is located radially outward of these components in the tire radial cross section.

[0025] "Normal condition" refers to a condition in which the tire is mounted on a normal rim and filled with air at normal internal pressure, with no load applied.

[0026] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. In the case of a tire not specified in the above standards, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the tire and can maintain internal pressure (i.e., no air leaks from between the rim and tire).

[0027] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA, it is "maximum air pressure," for ETRTO, it is "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and follow that standard if there is an applicable size at the time of reference. In the case of tires not specified in the above standards, it refers to the normal internal pressure (250kPa or more) of another tire size (defined in the standard) that is specified using the regular rim as the standard rim, and if there are multiple normal internal pressures of 250kPa or more listed, it refers to the smallest value among them.

[0028] "Normal load" refers to the load specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA it is "Maximum Load Capacity", for ETRTO it is "Load Capacity", and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with normal rims and normal internal pressures, JATMA, ETRTO, and TRA should be referenced in that order, and if there is an applicable size at the time of reference, that standard should be followed. For tires not specified in the above standards, the maximum load capacity W calculated separately should be used. L is the normal load.

[0029] "Maximum load capacity W L " is calculated using the following formula: "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter (mm) of the tire in its normal state, "Ht" is the tire's cross-sectional height (mm) in the tire's radial direction in a cross section of the tire taken along a plane including the tire's rotation axis, and "Wt" is the tire's cross-sectional width (mm) in its normal state. Ht can be calculated by (Dt-R) / 2, where R is the tire rim diameter. Wt is the value obtained by excluding any patterns or letters on the tire sidewall. Note that maximum load capacity is synonymous with the normal load mentioned above.

[0030]

number

[0031] "Tread thickness T (mm)" is the thickness of the entire tread measured along a normal to the tread contact surface at the tire equator in a cross section passing through the tire rotation axis. When the tire has circumferential grooves on the equator, it is the thickness measured along a normal to the tread contact surface at the tire widthwise center of the land portions present on both sides of the groove in the tire widthwise direction, the land portions having a center in the tire width direction closest to the tire equatorial plane.

[0032] "Particle size of rubber powder" is the mass-based average particle size calculated from the particle size distribution measured in accordance with JIS K 6316:2017 "Test method for rubber powder" using a test sieve specified in JIS Z 8801-1:2019.

[0033] The "BET specific surface area of ​​rubber powder" can be determined by JIS Z 8830: BET one-point method (adsorption gas: nitrogen).

[0034] The "BET specific surface area of ​​carbon black" is measured in accordance with JIS K 6217-2:2017 "Basic properties of carbon black for rubber - Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0035] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by pyrolysis gas chromatography, and is applied to rubber components having repeating units derived from butadiene, such as SBR and BR. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated in a pyrolysis device, the individual components contained in the gas phase components generated by this heating are separated using a separation column, and each isolated component is analyzed.

[0036] The "weight average molecular weight (Mw)" can be determined by converting the measured value into standard polystyrene equivalents using gel permeation chromatography (GPC) (for example, a GPC-8000 series manufactured by Tosoh Corporation, a differential refractometer as the detector, and a TSKgel SuperMultipore HZ-M column manufactured by Tosoh Corporation). This applies to, for example, SBR, BR, plasticizers, etc.

[0037] The "average primary particle size of carbon black" is a value determined by photographing particles with a transmission or scanning electron microscope and taking the arithmetic mean of the particle sizes of 400 particles. If the particle shape is spherical, the particle size is the diameter of the sphere; if the particle shape is non-spherical, the particle size is calculated from the microscope image as the circle-equivalent diameter (positive square root of {4 × (particle area) / π}).

[0038] "Plasticizer" is a material that imparts plasticity to rubber components and is a component that is extracted from rubber compositions using acetone. Plasticizers include those that are liquid (fluid) at 25°C and those that are solid at 25°C. However, this does not include waxes and stearic acid, which are commonly used in the tire industry.

[0039] The "plasticizer content" also includes the amount of plasticizer in the rubber component extended by the plasticizer.

[0040] [tire] A tire according to one embodiment of the present invention will be described below with reference to the drawings. The tire according to this embodiment has a tread portion, and the tread portion is made of a rubber composition containing a rubber component, carbon black, and rubber crumb, and when the content of carbon black per 100 parts by mass of the rubber component of the rubber composition is C (parts by mass), C is greater than 20, the rubber crumb contains sulfur element, the particle size of the rubber crumb is 40 mesh or more, and the BET specific surface area of ​​the rubber crumb is B (m 2 / g), B is 0.100 or more, and when the thickness of the tread portion is T (mm), T is 3.0 or more, and when the content of rubber powder per 100 parts by mass of the rubber component of the rubber composition is A (parts by mass), A / T is less than 20, and the BET specific surface area of ​​the carbon black is E (m 2 / g), (C×E) / (A×B) is greater than 1000, preferably greater than 1500. Note that the embodiment described below is merely an example, and the tire of the present invention is not limited to the embodiment described below.

[0041] Fig. 1 is a diagram showing a portion of a cross section passing through the tire rotation axis of a tread portion of a tire according to one embodiment of the present invention. The tire of Fig. 1 has a tread portion 1 that comes into contact with the ground when running, and a belt layer 8 on the radially inner side of the tread portion 1. A carcass 9 and an inner liner 7 are laminated below the belt layer 8. A band may also be present between the tread portion 1 and the belt layer 8. In Fig. 1, the belt layer 8 is laminated in two layers, and a band 11 having a jointless structure is disposed inside the base rubber layer 4.

[0042] The tread portion 1 in FIG. 1 has two layers: a cap rubber layer 2 that includes the tire contact surface, and a base rubber layer 4 that is adjacent to the cap rubber layer 2 on the radially inner side of the tire. The tread portion 1 according to this embodiment may be a single layer or may be two or more layers, and two or more layers are preferable. When the tread portion has two or more layers, for example, the tread portion 1 may be a tread portion consisting of two layers, the cap rubber layer 2 and the base rubber layer 4, as shown in FIG. 1. Furthermore, one or more intermediate rubber layers may be further provided between the cap rubber layer 2 and the base rubber layer 4, and one or more undertread layers may be further provided between the base rubber layer 4 and the belt layer 8.

[0043] From the viewpoint of ride comfort, the thickness T of the tread portion is 3.0 mm or more, preferably 3.2 mm or more, more preferably 3.4 mm or more, even more preferably 3.5 mm or more, and particularly preferably 3.7 mm or more. There is no upper limit to the thickness T of the tread portion, but it is preferably 15.0 mm or less, more preferably 10.0 mm or less, even more preferably 8.0 mm or less, and particularly preferably 7.0 mm or less.

[0044] From the viewpoint of the effects of the present invention, A / T is less than 20, preferably less than 16, and more preferably less than 10. Furthermore, A / T is preferably greater than 1.5, more preferably greater than 2.0, and even more preferably greater than 2.5. A is the content of rubber powder per 100 parts by mass of the rubber component of the rubber composition constituting the tread portion, and a preferred range of A will be described later.

[0045] From the viewpoint of the effects of the present invention, (C×E) / (A×B) is greater than 1000, preferably greater than 1500, more preferably greater than 2000, even more preferably greater than 2500, still more preferably greater than 3000, and particularly preferably greater than 3500. Furthermore, (C×E) / (A×B) is preferably less than 8000, more preferably less than 7500, and even more preferably less than 7000. The ranges of B and E will be described later.

[0046] C×T is preferably greater than 100, more preferably greater than 120, even more preferably greater than 145, still more preferably greater than 160, and particularly preferably greater than 180. C×T is preferably less than 300, more preferably less than 280, and still more preferably less than 270. C is the content of carbon black per 100 parts by mass of the rubber component of the rubber composition constituting the tread, and the range of C will be described later.

[0047] C / A is preferably at least 5, more preferably at least 6, and even more preferably at least 7. There is no particular upper limit to C / A, but it can be set to, for example, 20 or less.

[0048] A×T is preferably equal to or less than 50, more preferably equal to or less than 45, and even more preferably equal to or less than 40. There is no particular lower limit to A×T, but it can be, for example, 10 or more.

[0049] B×E is preferably at least 15, more preferably at least 20, and even more preferably at least 25. There is no particular upper limit to B×E, but it can be set to, for example, 50 or less.

[0050] When the rubber composition constituting the tread portion has two or more layers, it is sufficient that any one of the rubber compositions constituting the tread portion satisfies C, B, A, A / T, and (C×E) / (A×B), but it is preferable that the cap rubber layer satisfies them.

[0051] [Rubber composition] The rubber composition constituting the tread portion of the tire of this embodiment will be described below: The rubber composition according to this embodiment contains a rubber component, carbon black, and rubber powder.

[0052] <Rubber component> The rubber component preferably contains a diene rubber. The content of the diene rubber in the rubber component is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more. The rubber component may be made of only the diene rubber.

[0053] As the diene rubber, any of those commonly used in the tire industry can be suitably used. Specific examples include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), etc. These diene rubbers may be used alone or in combination of two or more.

[0054] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0055] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SIR20, RSS#3, and TSR20.

[0056] The content of the isoprene-based rubber in the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more from the viewpoint of abrasion resistance, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less from the viewpoint of improving the dispersibility of the filler.

[0057] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc. These BRs may be used alone or in combination of two or more.

[0058] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the above-mentioned measurement method.

[0059] The rare earth BR is synthesized using a rare earth catalyst and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. As the rare earth BR, for example, commercially available products from LANXESS K.K. can be used.

[0060] The SPB-containing BR is not simply 1,2-syndiotactic polybutadiene crystals dispersed in the BR, but is dispersed after being chemically bonded to the BR. As such SPB-containing BR, commercially available products from UBE Corporation and the like can be used.

[0061] As the modified BR, for example, a modified butadiene rubber (modified BR) whose terminals and / or main chain are modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen can be suitably used.

[0062] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0063] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably more than 300,000, more preferably more than 350,000, and even more preferably more than 400,000. From the viewpoint of crosslink uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 500,000. Mw can be determined by the above-mentioned method.

[0064] From the viewpoint of improving the dispersibility of the filler, the content of BR in the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more. From the viewpoint of abrasion resistance, the content of BR in the rubber component is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0065] (SBR) The SBR is not particularly limited, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose ends and / or main chains are modified, and modified SBRs (condensates, those having a branched structure, etc.) coupled with tin, silicon compounds, etc. Furthermore, hydrogenated products of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used alone or in combination of two or more.

[0066] As the SBR, either oil-extended or non-oil-extended SBR can be used. In this specification, commercially available SBRs from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, etc. can be used.

[0067] The content of SBR in the rubber component is preferably less than 50% by mass, more preferably less than 30% by mass, even more preferably less than 20% by mass, and particularly preferably less than 10% by mass. The rubber composition according to this embodiment does not necessarily contain SBR as the rubber component. When SBR is contained, the content in the rubber component is preferably 1% by mass or more.

[0068] (Other rubber components) The rubber component may contain a rubber component other than the diene rubber (non-diene rubber) to the extent that it does not affect the effects of the invention. Examples of non-diene rubbers include rubber components commonly used in the tire industry, such as butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0069] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are structural units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0070] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0071] Furthermore, the monomers that are the structural units of polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0072] Monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited, and examples include biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0073] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited and include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0074] Whether a polymer's raw material is biomass-derived can be determined by its pMC (percent modern carbon) measured in accordance with ASTM D6866-10. pMC is the modern standard reference carbon. 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0075] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14 C exists. 14 The half-life of C is 5730 years, 14 C is decreasing regularly. Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C elements.

[0076] on the other hand, 14C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 The amount of C is balanced between radioactive decay and nuclear reaction, and in the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0077] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14 The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0078] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will usually not reach 100 under normal conditions, so it will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels,14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the above-mentioned biomass ratio of 0%.

[0079] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0080] [Filler] The rubber composition according to the present embodiment contains carbon black as a filler, but the filler may consist solely of carbon black.

[0081] <Carbon black> Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by pyrolysis of methane, such as in a thermal black process. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These carbon blacks may be used alone or in combination.

[0082] In addition to the above, from the viewpoint of life cycle assessment, carbon black may be made from a biomass material such as lignin, or recycled carbon black obtained by pyrolysis and purification of a product containing carbon black, such as a tire.

[0083] As used herein, "recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of the mass of ash (ash content), which is the non-combustible component, is 13% by mass or more. In other words, the proportion of the mass (carbon content) of the recycled carbon black lost due to oxidative combustion is 87% by mass or less. Recycled carbon black is sometimes expressed as rCB.

[0084] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes the carbon black as being obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes typically lacks functional groups on its surface, as mentioned in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of the Surface Morphology and Chemistry of Pyrolytic Carbon Black with Commercial Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0085] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3,173,251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black of this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0086] As the recycled carbon black, commercially available products from Strable Green Carbon, LD Carbon, etc. can be used.

[0087] From the viewpoint of the effect of the present invention, the BET specific surface area E of the carbon black is 70 m 2 / g or more is preferable, and 90m 2 / g is more preferable, and 100m 2 / g or more is more preferable, and 110m 2 From the viewpoint of heat buildup and processability, it is particularly preferable that the tensile strength is more than 250 m / g. 2 / g is preferable, and 200m 2 / g is more preferable, and 180m 2 The BET specific surface area of ​​carbon black is measured by the above-mentioned measuring method.

[0088] The average primary particle size of carbon black is preferably greater than 9 nm, more preferably greater than 10 nm, and even more preferably greater than 12 nm. The average primary particle size is preferably less than 51 nm, more preferably less than 50 nm, and even more preferably less than 45 nm. The average primary particle size of carbon black is measured by the above-mentioned measurement method.

[0089] The carbon black content C per 100 parts by mass of the rubber component is more than 20 parts by mass, more preferably more than 30 parts by mass, even more preferably more than 40 parts by mass, and particularly preferably more than 50 parts by mass. The carbon black content C per 100 parts by mass of the rubber component is preferably less than 120 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 80 parts by mass, and particularly preferably less than 70 parts by mass.

[0090] <Other fillers> The rubber composition according to the present embodiment may contain fillers other than carbon black. The other fillers are not particularly limited, but may include, for example, silica, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other fillers that have been commonly used in the tire industry.

[0091] <Silica> The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is also not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0092] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0093] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0094] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222). Amorphous silica extracted from rice husks can be commercially available from Wilmar, Inc.

[0095] When silica is contained, the amount of silica per 100 parts by mass of the rubber component is preferably less than 100 parts by mass, more preferably less than 60 parts by mass, even more preferably less than 30 parts by mass, still more preferably less than 20 parts by mass, and particularly preferably less than 10 parts by mass. The lower limit of the amount of silica per 100 parts by mass of the rubber component can be, for example, 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more.

[0096] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent.Silane coupling agent is not particularly limited, but for example, sulfide-based silane coupling agent such as bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agent such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane Examples of suitable silane coupling agents include amino-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. Examples of suitable silane coupling agents include those commercially available from Evonik Degussa GmbH and Momentive GmbH. These silane coupling agents may be used alone or in combination.

[0097] The content of the silane coupling agent is preferably more than 3 parts by mass, more preferably more than 6 parts by mass, and even more preferably more than 9 parts by mass relative to 100 parts by mass of silica from the viewpoint of improving the dispersibility of silica. Also, from the viewpoint of cost and processability, the content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass relative to 100 parts by mass of silica.

[0098] The content of the silane coupling agent per 100 parts by mass of the rubber component (the total amount when multiple silane coupling agents are used) is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and even more preferably 3 parts by mass or more, from the viewpoint of improving the dispersibility of silica. Also, from the viewpoint of preventing a decrease in abrasion resistance, the content is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and particularly preferably less than 5 parts by mass.

[0099] [Rubber powder] The rubber composition according to this embodiment contains rubber crumb containing elemental sulfur. The rubber crumb may be a commercially available rubber crumb obtained by crushing used tires using a roller or grinder and then sieving the crumb to a predetermined particle size, or may be a rubber crumb obtained by vulcanizing a separately formulated rubber composition, crushing it, and sieving it. From the standpoints of environmental consideration and cost, recycled rubber crumb produced from crushed waste tires or the like is preferred. One type of rubber crumb may be used alone, or two or more types may be used in combination.

[0100] The rubber powder may be unmodified or modified.

[0101] An example of a method for producing rubber powder by vulcanizing a separately compounded rubber composition, pulverizing, and sieving the vulcanized rubber composition is the method disclosed in JP-A-2023-113413.

[0102] As commercially available rubber powder, for example, products from Tire Recycling Solutions, Lehigh Technologies, Muraoka Rubber Industries Co., Ltd., etc. can be used.

[0103] The content of elemental sulfur in the rubber crumb is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 5.0% by mass or less, more preferably 4.5% by mass or less, and even more preferably 4.0% by mass or less.

[0104] From the viewpoint of the effects of the present invention, the particle size of the rubber powder is 40 mesh or more, preferably 50 mesh or more, and from the viewpoint of dispersibility, the particle size of the rubber powder is preferably 300 mesh or less, more preferably 250 mesh or less, even more preferably 200 mesh or less, still more preferably 150 mesh or less, and particularly preferably 100 mesh or less.

[0105] The BET specific surface area B of the rubber powder is 0.100 m from the viewpoint of improving the reinforcing effect. 2 / g or more, and 0.110m 2 / g or more is preferable, and 0.115m 2 / g or more is more preferable. The BET specific surface area B of the rubber powder is 0.200 m 2 / g or less is preferable, and 0.150m 2 / g or less is more preferable, and 0.130m 2 / g or less is more preferable.

[0106] From the viewpoint of the effects of the present invention, the content A of rubber powder per 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. Moreover, the content A of rubber powder is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 60 parts by mass or less.

[0107] [Other compounding agents] In addition to the rubber component, filler, and rubber powder, the rubber composition may contain compounding agents conventionally commonly used in the tire industry, such as plasticizers, processing aids, waxes, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators, as appropriate.

[0108] <Plasticizer> A plasticizer is a material that imparts plasticity to rubber components and encompasses both liquid and solid plasticizers at 25°C. Examples of plasticizers include resins, oils, liquid rubbers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived materials, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. Plasticizers may be used singly or in combination.

[0109] (resin) Of the other compounding ingredients, the rubber composition preferably contains a resin. The resin is not particularly limited, but resins commonly used in the tire industry can be used, such as aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. Of these, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, and terpene resins are preferred. The resins may be used alone or in combination of two or more.

[0110] <Aromatic vinyl resin> The term "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc., as the monomer component with the highest content, and may be a hydrogenated or modified version of such a compound. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, for example, commercially available products from Kraton, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. These aromatic vinyl resins may be used alone or in combination of two or more.

[0111] <Dicyclopentadiene resin> The term "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene (DCPD) as the monomer component with the highest content, and may be a hydrogenated or modified resin. Examples of dicyclopentadiene-based resins include DCPD / C9 resins obtained by copolymerizing dicyclopentadiene with the C9 fraction, with DCPD / C9 resins being preferred. Examples of DCPD resins that can be used include those commercially available from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., and the like. These dicyclopentadiene-based resins may be used singly or in combination of two or more.

[0112] <C9 resin> The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction. It may be a C9 fraction polymerized alone or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. These resins may also be hydrogenated or modified. Examples of C9 fractions include at least one petroleum fraction having 8 to 10 carbon atoms selected from the group consisting of vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. Specific examples of C9 resins include coumarone-indene resin, coumarone resin, and indene resin. These C9 resins may be used alone or in combination.

[0113] <C5 resin> "C5 resin" refers to a resin obtained by polymerizing a C5 fraction other than dicyclopentadiene, and may be a hydrogenated or modified version of such a resin. Examples of C5 fractions other than dicyclopentadiene include at least one petroleum fraction having 4 to 5 carbon atoms selected from the group consisting of cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. These C5 resins may be used alone or in combination of two or more.

[0114] <C5C9 resin> The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. As the C5C9 resin, for example, commercially available resins from Tosoh Corporation, LUHUA, etc. may be used. These C5C9 resins may be used alone or in combination of two or more.

[0115] <Terpene resin> Terpene resins refer to resins containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the largest content of the monomer component, and may be hydrogenated or modified. Specific examples of terpene resins include polyterpene resins containing only one or more of the terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compound and an aromatic compound as monomer components; and terpene phenolic resins containing the terpene compound and a phenolic compound as monomer components. Examples of aromatic compounds that serve as monomer components for aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that serve as monomer components for terpene phenolic resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. These terpene resins may be used alone or in combination.

[0116] ≪Rosin resin≫ The rosin resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and may be a hydrogenated or modified product thereof. The rosin resin is not particularly limited, and examples thereof include natural resin rosin, rosin-modified resins obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin resins may be used alone or in combination of two or more.

[0117] ≪Phenolic resin≫ The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the highest content. The phenolic resin is not particularly limited, and examples thereof include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. These phenolic resins may be used alone or in combination of two or more.

[0118] ≪Content≫ From the viewpoint of wet grip performance, the content of the resin with respect to 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably more than 5 parts by mass. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably less than 40 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass.

[0119] (Plasticizer other than resin) Oils, liquid rubbers, and ester plasticizers, which are plasticizers other than resins, will be described.

[0120] (Oil) Examples of oils include mineral oil, vegetable oil, and animal oil. From the viewpoint of life cycle assessment, waste oils used in rubber mixers and engines, and refined waste cooking oils used in restaurants may also be used. One type of oil may be used alone, or two or more types may be used in combination.

[0121] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extracted solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0122] In this specification, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils obtained by interesterifying the above oils, hardened oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and waste edible oils recovered from edible oils. Vegetable oils may be liquid or solid at 25°C.

[0123] When oil is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 5 parts by mass, even more preferably more than 10 parts by mass, and particularly preferably more than 12 parts by mass, from the viewpoint of processability. The content is also preferably less than 50 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass.

[0124] (liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25° C., and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. One type of liquid rubber may be used alone, or two or more types may be used in combination.

[0125] (ester plasticizer) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). One type of ester-based plasticizer may be used alone, or two or more types may be used in combination.

[0126] The amount of plasticizer per 100 parts by mass of the rubber component (the total amount when multiple plasticizers are used) is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably more than 12 parts by mass, and particularly preferably more than 14 parts by mass. From the viewpoint of processability, the amount is preferably less than 60 parts by mass, more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass. The amount of plasticizer also includes the amount of extension plasticizers such as extension oil, extension resin, extension liquid rubber component, and extension ester-based plasticizer used to extend the rubber component.

[0127] (processing aids) Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used alone or in combination of two or more. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc.

[0128] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of improving processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance and breaking strength.

[0129] (wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. One type of wax may be used alone, or two or more types may be used in combination.

[0130] When wax is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of weather resistance of the rubber, and is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of preventing whitening of the tire due to bloom.

[0131] (anti-aging agent) The antioxidant is not particularly limited, but examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl ... p-phenylenediamine-based antioxidants such as diphenyldiamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis Co., Ltd. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0132] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 parts by mass, and even more preferably more than 1.4 parts by mass from the viewpoint of ozone crack resistance of the rubber, and is preferably less than 2.5 parts by mass, more preferably less than 2.0 parts by mass, and even more preferably less than 1.8 parts by mass from the viewpoint of abrasion resistance and wet grip performance.

[0133] (stearic acid) When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of vulcanization rate.

[0134] (zinc oxide) When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance.

[0135] (vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. Examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more.

[0136] When sulfur is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.8 parts by mass, and even more preferably more than 1.2 parts by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 3.0 parts by mass. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0137] Known organic crosslinking agents can also be used as vulcanizing agents other than sulfur. The organic crosslinking agent is not particularly limited as long as it can form crosslinked chains other than polysulfide bonds. Examples of the organic crosslinking agent include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, and other companies.

[0138] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited, but examples thereof include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde-amine vulcanization accelerators, aldehyde-ammonia vulcanization accelerators, imidazoline vulcanization accelerators, xanthate vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used alone or in combination of two or more. Among them, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferred, as they more suitably achieve the desired effects. The vulcanization accelerators may be used alone or in combination of two or more.

[0139] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0140] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or a salt thereof, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole.

[0141] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

[0142] Examples of thiuram vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylene thiuram disulfide, and dipentamethylene thiuram tetrasulfide.

[0143] Examples of the thiourea vulcanization accelerator include thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea and diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea and N,N'-diethylthiourea.

[0144] Examples of dithiocarbamate vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC).

[0145] When a vulcanization accelerator is contained, the content (total amount when multiple vulcanization accelerators are used) per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2.0 parts by mass. The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably less than 8.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably less than 4.0 parts by mass.

[0146] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining such various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0147] [Manufacturing] The rubber composition can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0148] The kneading process may include, for example, a base kneading process in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) process in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading process and kneaded. Furthermore, the base kneading process may be divided into multiple processes as desired. When the base kneading process is divided, the method may be (1) a method in which some of the compounding ingredients and additives are pre-mixed to form a masterbatch, and then the remaining compounding ingredients and additives are added to the resulting masterbatch and kneaded, or (2) a method in which all of the compounding ingredients and additives to be kneaded in the base kneading process are kneaded at once, and then the kneaded product is remilled one or more times. In the above method (1), the number of masterbatches is not limited and may be two or more. Furthermore, when the number of masterbatches is two or more, all of the compounding ingredients and additives used in the base kneading process may be allocated to one of the masterbatches.

[0149] The kneading conditions are not particularly limited, but examples thereof include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading step involves kneading for 1 to 5 minutes at 70 to 110°C. The vulcanization conditions are not particularly limited, but examples thereof include a method in which vulcanization is carried out for 10 to 30 minutes at 150 to 200°C.

[0150] The tire according to the present embodiment can be manufactured by a conventional method using the rubber composition. That is, the unvulcanized rubber composition is extruded to match the shape of the tread portion using an extruder equipped with a die of a predetermined shape, and then laminated together with other tire components in a tire building machine while adjusting to obtain a predetermined tire structure, and molded by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer, whereby the tire can be manufactured. The vulcanization conditions are not particularly limited, and examples thereof include a method of vulcanizing at 140 to 170°C for 10 to 40 minutes.

[0151] [Application] The tire according to the present embodiment can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Among these, a passenger car tire is preferable. Note that a passenger car tire is a tire designed to be mounted on a four-wheeled vehicle, and refers to a tire with a maximum load capacity of less than 1,400 kg. Furthermore, the tire according to the present embodiment can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Example]

[0152] The following examples (working examples) are considered to be preferable for carrying out the present invention, but the scope of the present invention is not limited to these working examples. Rubber compositions and tires obtained according to the tables were examined using the various chemicals shown below, and the results calculated based on the evaluation methods described below are shown in Tables 1 and 2.

[0153] <Various chemicals> The chemicals used in the examples and comparative examples are summarized below. NR:TSR20 BR: UBEPOL BR (registered trademark) 150B (unmodified BR, cis content: 97 mol%, Mw: 440,000) manufactured by UBE Corporation Carbon black 1: VULCAN 6 (N220) manufactured by Cabot Japan Co., Ltd., BET specific surface area: 114 m 2 / g) Carbon black 2: VULCAN 10H (N134, BET specific surface area: 143 m) manufactured by Cabot Japan Co., Ltd. 2 / g) Rubber powder 1: Tyrexol CW50 manufactured by Tyre Recycling Solutions (rubber powder containing sulfur, 50 mesh, BET specific surface area: 0.115 m) 2 / g) Rubber powder 2: Lehigh Technologies MicroDyne 400 (40 mesh, BET specific surface area: 0.066 m)2 / g) Oil: Diana Process Oil AH-40 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Noccela CZ (CBS, N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0154] Examples and Comparative Examples According to the compounding formulations shown in Tables 1 and 2, chemicals other than sulfur and vulcanization accelerators are kneaded for 1 to 10 minutes using a 1.7 L closed-type Banbury mixer until the discharge temperature reaches 150 to 160°C, to obtain a kneaded mixture. Next, sulfur and vulcanization accelerators are added to the kneaded mixture using a two-screw open roll, and the mixture is kneaded for 4 minutes until the temperature reaches 105°C, to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded to fit the shape of the tread portion, and laminated together with other tire components to produce an unvulcanized tire. The tire is then press-vulcanized at 150°C for 35 minutes to obtain each test tire shown in Tables 1 and 2.

[0155] <Wear resistance> Each vulcanized rubber test piece was prepared by cutting a test piece measuring 20 mm in length, 4 mm in width, and 1 mm in thickness from the tread portion of each test tire, with the long side aligned in the tire circumferential direction. Using an LAT (Laboratory Abration and Skid Tester) tester, the weight loss of each test piece was measured under conditions of a load of 100 N, a speed of 20 km / h, and a slip angle of 6°, and the abrasion resistance of each tire was expressed as an index using the following calculation formula. A higher index indicates better abrasion resistance. The reference comparative example is Comparative Example 1 in Table 1 and Comparative Example 8 in Table 2. Abrasion resistance = (weight loss of the reference comparative example) / (weight loss of each test piece) × 100

[0156] <Ride comfort> Each test tire is inflated with 250 kPa of air and mounted on a 2000 cc automobile. The automobile is driven on an asphalt test course at a speed of 100 km / h, and the test driver performs a sensory evaluation of the ride comfort. The evaluation is performed using an integer value of 1 to 5, with a higher score indicating better ride comfort performance, and the total score of the 10 test drivers is calculated based on this evaluation standard. The total score of the reference comparative example is converted to a reference value (100), and the evaluation result of each test tire is displayed as an index proportional to the total score. The reference comparative example is Comparative Example 1 in Table 1 and Comparative Example 8 in Table 2.

[0157] <Overall performance> The total value of the abrasion resistance performance and the ride comfort performance is shown as an overall performance index.

[0158] [Table 1]

[0159] [Table 2]

[0160] <Embodiment> Examples of embodiments of the present invention are given below. [1] A tire having a tread portion, the tread portion is made of a rubber composition containing a rubber component, carbon black, and rubber powder, When the content of carbon black per 100 parts by mass of the rubber component of the rubber composition is C (parts by mass), C is more than 20, The rubber crumb contains elemental sulfur, The particle size of the rubber powder is 40 mesh or more, The BET specific surface area of ​​the rubber powder is defined as B (m 2 / g), B is 0.100 or more, When the thickness of the tread portion is T (mm), T is 3.0 or more, When the content of rubber powder relative to 100 parts by mass of the rubber component of the rubber composition is A (parts by mass), A / T is less than 20, The BET specific surface area of ​​the carbon black is defined as E (m 2 / g), A tire in which (C×E) / (A×B) is greater than 1000, preferably greater than 1500. [2] The tire according to [1] above, wherein the A / T is less than 10. [3] The tire according to [1] or [2] above, wherein (C×E) / (A×B) is greater than 2000, preferably greater than 2500, and more preferably greater than 300. [4] The tire according to any one of the above [1] to [3], wherein C×T is greater than 100, preferably greater than 120, more preferably greater than 145, and even more preferably greater than 160, with respect to C and T. [5] The E(m 2 The tire according to any one of the above [1] to [4], wherein the tensile strength (T / g) is greater than 100, preferably greater than 110. [6] The tire according to any one of the above [1] to [5], wherein the rubber component contains 30% by mass or more of an isoprene-based rubber. [7] The tire according to any one of the above [1] to [6], wherein the rubber component contains 50% by mass or more of butadiene rubber. [Explanation of symbols]

[0161] 1 Tread section 2 Cap rubber layer 4 Base rubber layer 7 Inner liner 8 Belt Layers 9. Carcass 11 bands CL Tire equatorial plane T Tread thickness

Claims

1. A tire having a tread portion, the tread portion is made of a rubber composition containing a rubber component, carbon black, and rubber powder, When the content of carbon black per 100 parts by mass of the rubber component of the rubber composition is C (parts by mass), C is more than 20, The rubber crumb contains elemental sulfur, The particle size of the rubber powder is 40 mesh or more, The BET specific surface area of ​​the rubber powder is B (m 2 / g), B is 0.100 or more, When the thickness of the tread portion is T (mm), T is 3.0 or more, When the content of rubber powder relative to 100 parts by mass of the rubber component of the rubber composition is A (parts by mass), A / T is less than 20, The BET specific surface area of ​​the carbon black is defined as E (m 2 / g), A tire in which (C×E) / (A×B) is greater than 1000.

2. The tire of claim 1 wherein the A / T is less than 10.

3. 3. The tire according to claim 1 or 2, wherein (C x E) / (A x B) is greater than 2000.

4. The tire according to claim 1 or 2, wherein C×T is greater than 100 for C and T.

5. The E(m 2 3. The tire according to claim 1 or 2, wherein the tensile strength of the tire is 100.

6. The tire according to claim 1 or 2, wherein the rubber component contains 30% by mass or more of an isoprene-based rubber.

7. The tire according to claim 1 or 2, wherein the rubber component contains 50% by mass or more of butadiene rubber.

Images