Rubber composition for tires and tires

Abstract

The present invention provides a rubber composition for tires and a tire that can improve both ice performance and wear resistance. [Solution] A tire having a tread, the tread being formed from a tire rubber composition containing isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles, wherein the total mass A (g) of water-soluble particles in the tread and the actual contact area B (cm²) of the tread 2 A tire whose ratio (A / B) is 0.60 or greater.

Description

Technical Field

[0001] The present invention relates to a rubber composition for tires and a tire.

Background Art

[0002] Spike tires have been used for driving on icy and snowy roads, and chains have been attached to tires. However, environmental problems such as dust problems have occurred, and studless tires have been proposed as an alternative. Since studless tires are used on icy and snowy road surfaces with larger road surface irregularities than general road surfaces, various improvements have been proposed in terms of materials and design (for example, Patent Documents 1 to 3).

[0003] However, in these conventional technologies, the compatibility between ice performance such as grip performance on icy and snowy road surfaces and wear resistance has not yet been sufficient, and further improvement is required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above situation, and an object thereof is to provide a rubber composition for tires and a tire that can improve both ice performance and wear resistance.

Means for Solving the Problems

[0006] The present invention is a tire provided with a tread, The aforementioned tread is The tire rubber composition contains isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles. The total mass A (g) of the water-soluble particles in the tread and the actual contact area B (cm²) of the tread. 2 This tire is characterized by having a ratio (A / B) of 0.60 or greater.

[0007] Furthermore, the present invention is A rubber composition for tires for forming the tread of the aforementioned tire, This tire rubber composition is characterized by containing isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a rubber composition for tires and a tire that can improve both ice performance and wear resistance. [Modes for carrying out the invention]

[0009] [1] Features of the present invention First, the features of the present invention will be described.

[0010] 1. Overview The tire according to the present invention is a tire having a tread, and the tread is formed of a tire rubber composition containing isoprene-based rubber and conjugated diene-based rubber as rubber components. This tire rubber composition contains a conjugated diene-based polymer having acidic functional groups and water-soluble particles. Furthermore, the total mass A (g) of the water-soluble particles in the tread and the actual contact area B (cm²) of the tread are given. 2 The ratio (A / B) to ) is 0.60 or greater.

[0011] Furthermore, the rubber composition for tires according to the present invention is a rubber composition for forming the tread of a tire according to the present invention, and contains isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles.

[0012] By possessing these characteristics, it is possible to provide a tire rubber composition and tire that can improve both ice performance and wear resistance, as will be described later.

[0013] 2. Mechanism of effect in the present invention The mechanism by which the above-mentioned effects manifest in the present invention is thought to be as follows.

[0014] In the tire according to the present invention, the tire rubber composition that forms the tread contains isoprene-based rubber, which has excellent abrasion resistance, and conjugated diene-based rubber, which has excellent ice performance, as rubber components. Therefore, it is believed that both ice performance and abrasion resistance can be improved.

[0015] Furthermore, because the tire rubber composition contains water-soluble particles, when driving on ice, the water-soluble particles exposed on the tread's contact surface dissolve, forming fine irregularities on the contact surface. This is thought to improve grip performance on ice, i.e., ice performance.

[0016] Furthermore, since the tire rubber composition contains a conjugated diene polymer having acidic functional groups in addition to water-soluble particles, it is believed that the interaction between the acidic functional groups and the water-soluble particles appropriately controls the dissolution rate of the water-soluble particles during driving on ice, and that the effect of improving grip performance (ice performance) due to the dissolution of water-soluble particles is maintained over a long period of time.

[0017] Furthermore, the total mass A (g) of water-soluble particles in the tread and the actual contact area B (cm²) of the tread. 2By setting the ratio (A / B) to 0.60 or higher, and by making the total amount of water-soluble particles in the tread sufficiently large relative to the size of the tread's contact area, it is believed that the improvement in ice performance due to the dissolution of water-soluble particles will be further improved and maintained over a long period of time.

[0018] The combined effect of the above-mentioned factors results in a tire with excellent performance on ice and wear resistance, making it suitable for use as a studless tire.

[0019] The total mass A (g) of water-soluble particles in the tread is calculated from the amount (g) of rubber component contained in the rubber composition used to form the tread and the amount (parts by mass) of water-soluble particles per 100 parts by mass of rubber component.

[0020] Also, the actual contact area of ​​the tread B (cm²) 2 This can be determined from the contact shape under normal rim, normal internal pressure, and normal load conditions.

[0021] Specifically, the contact patch shape is obtained by mounting the tire to a standard rim, applying the standard internal pressure, letting it stand at 25°C for 24 hours, then applying ink to the tire tread surface, applying the standard load, pressing it onto cardboard (camber angle 0°), and transferring the shape to the cardboard. The tire is rotated 72° in the circumferential direction, and the transfer is performed at 5 locations. In other words, the contact patch shape is obtained 5 times. Actual contact area B (cm²) 2 ) is the average area of ​​the ink portion of the five contact shapes.

[0022] Here, "normal condition" refers to a state in which the tire is mounted on a normal rim, filled to the normal internal pressure, and under no load.

[0023] Furthermore, "standard rim" refers to the rim specified for each tire within 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 Organisation), 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." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standard, it refers to the rim with the smallest diameter and the narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage from between the rim and tire.

[0024] Furthermore, "standard internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, it refers to the "maximum air pressure" for JATMA, "INFLATION PRESSURE" for ETRTO, and the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA. Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standards, it refers to the standard internal pressure (but at least 250kPa) of another tire size (specified in the standards) that uses the standard rim as the standard rim. If multiple standard internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0025] Also, the "normal load" is the load defined for each tire in a standard system including the standards on which the above-mentioned tire is based, and refers to the maximum mass that can be allowed to be loaded on the tire. For JATMA, it is the maximum load capacity; for ETRTO, it is "LOAD CAPACITY"; for TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the cases of the above-mentioned "normal rim" and "normal internal pressure", refer to JATMA, ETRTO, and TRA in this order and comply with their standards. And for a tire not defined in the standards, the normal load W L is obtained by the following calculation. V = {(Dt / 2) 2 - (Dt / 2 - Ht) 2} × π × Wt W L = 0.000011 × V + 175 W L : Normal load (kg) V: Virtual volume of the tire (mm 3 ) Dt: Outer diameter Dt of the tire (mm) Ht: Section height of the tire (mm) Wt: Section width of the tire (mm)

[0026] [2] Embodiment Hereinafter, based on the embodiment, the present invention will be specifically described.

[0027] 1. Tire In the present embodiment, as described above, the rubber composition for tires forming the tread of the tire contains an isoprene rubber and a conjugated diene rubber as rubber components, and thereby it is considered that both the ice performance and the abrasion resistance can be improved.

[0028] And, as described above, the rubber composition for tires forming the tread has the total mass A (g) of the water-soluble particles and the actual contact area B (cm 2The ratio (A / B) to the actual contact area is 0.60 or higher, as the product contains a large amount of water-soluble particles relative to the actual contact area, and also contains a conjugated diene polymer with acidic functional groups. Therefore, it is thought that the interaction between the acidic functional groups and the water-soluble particles can appropriately control the dissolution rate of the water-soluble particles. This is thought to allow the improved grip performance to be maintained over a long period of time.

[0029] The (A / B) ratio is more preferably 0.63 or higher, and even more preferably 0.66 or higher. On the other hand, the upper limit is preferably 0.86 or lower, more preferably 0.83 or lower, and even more preferably 0.80 or lower.

[0030] 2. Rubber composition for tires The rubber composition for tires according to the present invention can be obtained from various compounding materials such as rubber components, conjugated diene polymers, water-soluble particles, fillers, softeners, vulcanizing agents, and vulcanization accelerators described below.

[0031] (1) Compounding materials (a) Rubber component The rubber component includes isoprene-based rubber and conjugated diene-based rubber.

[0032] (i) Isoprene rubber Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Common NR types used in the tire industry include SIR20, RSS#3, and TSR20, while common IR types include IR2200. Modified NR types include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified NR types include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IR types include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used individually or in combination of two or more types.

[0033] The isoprene-based rubber content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, from the viewpoint of ice performance and other factors. There is no particular upper limit, but it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0034] (b) Conjugated diene rubber As the conjugated diene rubber, for example, a polymer having repeating units derived from at least one monomer selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and myrcene can be used. In particular, a polymer having repeating units derived from at least one monomer selected from the group consisting of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene can be preferably used. That is, one preferred embodiment of the present invention is that the conjugated diene compound constituting the above conjugated diene rubber is at least one conjugated diene compound selected from the group consisting of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene. Among these, the above conjugated diene rubber is particularly preferably butadiene rubber (BR).

[0035] The type of butadiene rubber (BR) used is not particularly limited. Examples include BR with high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), butadiene rubber synthesized using rare earth element catalysts (rare earth-based BR), and tin-modified butadiene rubber modified with tin compounds (tin-modified BR), all of which are common in the tire industry. Commercially available BR products from companies such as Ube Industries, Ltd., ENEOS Material Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used. These may be used individually or in combination of two or more types.

[0036] The cis content of the above-mentioned conjugated diene rubber is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. This results in better ice performance.

[0037] The above cis content (cis-1,4-bond amount) is a value calculated from the signal intensity measured by infrared absorption spectroscopy or NMR analysis.

[0038] The content of conjugated diene rubber in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of ice performance and the like. There is no particular upper limit, but it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0039] The above-mentioned conjugated diene rubber can be either unmodified conjugated diene rubber or modified conjugated diene rubber. As the above-mentioned modified conjugated diene rubber, a conjugated diene rubber having a functional group that interacts with a filler such as silica can be used. For example, examples include terminally modified conjugated diene rubber (terminally modified conjugated diene rubber having the above-mentioned functional group at the end) in which at least one end of the conjugated diene rubber is modified with a compound (modifier) ​​having the above-mentioned functional group, main-chain modified conjugated diene rubber having the above-mentioned functional group in the main chain, main-chain terminally modified conjugated diene rubber having the above-mentioned functional group in the main chain and at least one end modified with the above-mentioned modifier (for example, main-chain terminally modified conjugated diene rubber having the above-mentioned functional group in the main chain and at least one end modified with the above-mentioned modifier), and terminally modified conjugated diene rubber that is modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and in which hydroxyl groups or epoxy groups are introduced.

[0040] Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0041] For example, as the above-mentioned modified conjugated diene rubber, a conjugated diene rubber modified with a compound (modifier) ​​represented by the following formula can be suitably used.

[0042] [ka]

[0043] Note that in the formula, R 1 , R 2 and R 3 R represents, either identical or distinct, an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 R represents a hydrogen atom or an alkyl group, either identical or different. 4 and R 5 These atoms may bond to form a ring structure with the nitrogen atom. n represents an integer.

[0044] As a modified SBR modified with the compound (modifying agent) represented by the above formula, SBR obtained by modifying the polymerization ends (active ends) of solution-polymerized styrene-butadiene rubber (S-SBR) with the compound represented by the above formula (such as the modified SBR described in Japanese Patent Publication No. 2010-111753) can be used.

[0045] R 1 , R 2 and R 3 A suitable alkoxy group is used (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 A suitable alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is used. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Also, R 4 and R 5 When the alkoxy group is bonded to form a ring structure with the nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group and benzyloxy group).

[0046] Preferred examples of the above-mentioned denaturing agents include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used individually or in combination of two or more.

[0047] In addition to the above-mentioned modified conjugated diene rubber, modified conjugated diene rubber modified with the following compounds (modifiers) can also be suitably used. Examples of modifiers include: polyglycyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxylated liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidylamino compounds such as diglycidyl orthotoluidine, tetoglycidylmetoxylendiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamate chloride, 4-morpholine carbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamate chloride, and N,N-diethylcarbamate chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (Rimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide Sulfide group-containing silane compounds such as [dipropoxysilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(di (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as thio(amino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; benzaldehyde compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone N-substituted pyrrolidones such as N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone; N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam;Other examples include N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Among these, modified conjugated diene rubbers modified with alkoxysilanes are preferred.

[0048] Furthermore, modification using the above-mentioned compound (modifying agent) can be carried out by known methods.

[0049] In the aforementioned rubber composition, the total content of isoprene-based rubber and conjugated diene-based rubber in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, and may be 100% by mass. The higher the total content, the better the low-temperature characteristics tend to be, and the better the desired ice performance can be exhibited.

[0050] The rubber composition may contain other rubber components as long as they do not inhibit the aforementioned effects. Examples of other rubber components include diene rubbers such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR).

[0051] (b) Conjugated diene polymers having acidic functional groups The rubber composition contains a conjugated diene polymer having an acidic functional group. The conjugated diene polymer having an acidic functional group is a solid or liquid polymer at room temperature, for example, 20°C. The acidic functional group is preferably at least one of a carboxyl group, a sulfate group, a hydroxyphenyl group, a phosphate group, or an acidic functional group derived therefrom, and more preferably a carboxyl group or an acidic functional group derived from a carboxyl group.

[0052] The conjugated diene polymer having acidic functional groups is contained in a dispersed state within the rubber component. It is believed that the interaction between the conjugated diene polymer having acidic functional groups and water-soluble particles further improves ice performance. The conjugated diene polymer having acidic functional groups can be produced by any polymerization method, may be a copolymer of multiple types of conjugated diene monomers, or may be a copolymer with monomers other than conjugated diene monomers.

[0053] The molecular weight of the conjugated diene polymer having acidic functional groups is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 60,000 or less, based on the weight-average molecular weight in styrene terms as determined by gel permeation chromatography (GPC). This ensures sufficient performance on ice.

[0054] As monomer units for conjugated diene polymers having acidic functional groups, for example, polymers having repeating units derived from at least one monomer selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and myrcene can be used. Styrene monomers and styrene derivative monomers may also be used as copolymer monomers.

[0055] The content of the conjugated diene polymer having acidic functional groups is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. This allows for a sufficient synergistic effect with the water-soluble particles. On the other hand, the upper limit is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the rubber component.

[0056] Conjugated diene polymers containing acidic functional groups are commercially available, such as Clay Valley's RICON MA series and Kuraray's LIR-410.

[0057] (c) Water-soluble particles Water-soluble particles can be used without any particular limitations, as long as they are fine particles that are soluble in water. For example, materials with a solubility of 1 g / 100 g of water or more at room temperature (20°C) can be used.

[0058] Examples of water-soluble particles include metal sulfates such as magnesium sulfate, sodium sulfate, and potassium sulfate; metal chlorides such as potassium chloride, sodium chloride, calcium chloride, and magnesium chloride; metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates such as potassium carbonate and sodium carbonate; and water-soluble inorganic salts such as sodium hydrogen phosphate and sodium dihydrogen phosphate. These may be used individually or in combination of two or more.

[0059] From the viewpoint of ice surface performance and other factors, the median particle size (median diameter, D50) of the water-soluble particles is preferably 1 μm or larger, more preferably 2 μm or larger, and even more preferably 3 μm or larger. The upper limit is preferably 1 mm or smaller, more preferably 500 μm or smaller, even more preferably 300 μm or smaller, and even more preferably 200 μm or smaller. The median particle size (median diameter, D50) can be measured by laser diffraction using a powder distribution analyzer such as the SALD-2000J manufactured by Shimadzu Corporation.

[0060] The lower limit of the water-soluble particle content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of rubber component. This tends to result in better ice performance.

[0061] On the other hand, the upper limit is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 40 parts by mass or less. This tends to result in better wear resistance.

[0062] The amount of water-soluble particles to be added should be determined based on the above trends and the actual contact area (cm²) of the tire tread being manufactured. 2 Based on the size of the particles and the mass (g) of the rubber components used in the tread, the total mass (g) of water-soluble particles / actual contact area (cm²) of the tread is calculated as follows: 2 ) is set appropriately so as to satisfy the value required for the tire.

[0063] (d) Filler (i) Silica The aforementioned rubber composition preferably contains silica as a filler from the viewpoint of ice performance and other factors. Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred because it contains a large number of silanol groups. Commercially available products include those from Evonik Industries, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation. These may be used individually or in combination of two or more types.

[0064] The silica content is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, and particularly preferably 60 parts by mass or more, per 100 parts by mass of rubber component. The upper limit of the content is not particularly limited, but is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 170 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 80 parts by mass or less. By setting the silica content within this range, good dispersibility of silica is obtained, and good ice performance tends to be obtained.

[0065] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 70 m². 2 / g or more, more preferably 140m 2 / g or more, more preferably 160m 2 It is 1 / g or more. Furthermore, the upper limit of N2SA in silica is not particularly limited, but preferably 500m 2 Less than / g, more preferably 300m 2 / g or less, more preferably 250m 2 It is less than / g. By setting the nitrogen adsorption specific surface area (N2SA) of silica within this range, good dispersibility of silica is obtained, and good ice performance tends to be achieved. Note that the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0066] Furthermore, if silica is included as a filler, it is preferable to also include a silane coupling agent. The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarb Examples include sulfide-based compounds such as moyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane.

[0067] Commercially available products from companies such as Evonik Industries, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and DuPont-Toray Specialty Materials, Ltd. can be used. These can be used individually or in combination of two or more types.

[0068] The silane coupling agent content is preferably 3 parts by mass or more, and more preferably 6 parts by mass or more, per 100 parts by mass of silica. Furthermore, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less. By setting the silane coupling agent content within this range, an effect commensurate with the amount added is obtained, and good ice performance tends to be obtained.

[0069] (b) Carbon Black Furthermore, the rubber composition preferably contains carbon black as a filler from the viewpoint of ice performance and other factors. The carbon black is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762.

[0070] Commercially available products from companies such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation can be used. These can be used individually or in combination of two or more types.

[0071] The carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of rubber component. Furthermore, the above content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. By setting the carbon black content within this range, good ice performance tends to be obtained.

[0072] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 50 m². 2 Preferably 80m / g or more. 2 More preferably 100m / g or more, 2 More preferably, the amount of N2SA is 200m 2 Preferably less than / g, 150m 2 More preferably less than / g, 130m 2A value of less than / g is even more preferable. By setting the nitrogen adsorption specific surface area (N2SA) of carbon black within this range, good dispersibility of the carbon black is obtained, and good ice performance tends to be achieved. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0073] (h) Combined use of silica and carbon black Furthermore, silica and carbon black may be used in combination as fillers. In this case, the silica content in 100% by mass of the total silica and carbon black content is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, from the viewpoint of ice performance and other factors.

[0074] (e) Plasticizers (i) Liquid plasticizer The rubber composition contains 30 parts by mass or less of liquid plasticizer per 100 parts by mass of rubber component. This provides good ice performance and other advantages. The content is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. The lower limit is not particularly limited, and liquid plasticizer may not be added at all, but from the viewpoint of ice performance and other advantages, 5 parts by mass or more is preferred, and 7 parts by mass or more is more preferred.

[0075] The liquid plasticizer is not particularly limited as long as it is a plasticizer that is in a liquid state at 20°C, and examples include oils, liquid resins, and liquid polymers. These may be used individually or in combination of two or more.

[0076] Examples of oils include process oils, vegetable oils, or mixtures thereof. Examples of process oils include paraffinic process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercial products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0077] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatically modified terpene resins) that are liquid at 20°C, rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene-only resins), phenolic resins, olefin resins, polyurethane resins, and acrylic resins.

[0078] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, and liquid farnesene-butadiene copolymer. These polymers may have polar groups attached to their ends or main chains.

[0079] (b) Solid plasticizers The rubber composition may contain resin (solid resin: resin that is solid at room temperature (25°C)). Examples of resin (solid resin) include aromatic vinyl polymers, coumarone indene resin, coumarone resin, indene resin, phenolic resin, rosin resin, petroleum resin, terpene resin, and acrylic resin.

[0080] Commercially available products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., and Toagosei Co., Ltd. can be used. These may be used individually or in combination of two or more types.

[0081] The above-mentioned aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and / or styrene, and includes homopolymers of styrene (styrene resin), homopolymers of α-methylstyrene (α-methylstyrene resin), copolymers of α-methylstyrene and styrene, and copolymers of styrene and other monomers.

[0082] Furthermore, the coumarone-indene resin mentioned above is a resin that contains coumarone and indene as the main monomer components that make up the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0083] Furthermore, the coumarone resin mentioned above is a resin that contains coumarone as the main monomer component constituting the resin's backbone (main chain). Furthermore, the indene resin mentioned above is a resin that contains indene as the main monomer component constituting the resin's backbone (main chain).

[0084] Furthermore, examples of the phenolic resins mentioned above include those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst. Among these, those obtained by reacting with an acid catalyst (such as novolac-type phenolic resins) are preferred.

[0085] Examples of the rosin resins mentioned above include natural rosin, polymerized rosin, modified rosin, their ester compounds, and rosin-based resins represented by their hydrogenated products.

[0086] Examples of the above-mentioned petroleum resins include C5 resins, C9 resins, C5 / C9 resins, and dicyclopentadiene (DCPD) resin.

[0087] As the terpene resins mentioned above, polyterpene resins obtained by polymerizing terpene compounds, and aromatically modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds can be used. Hydrogenated versions of these can also be used.

[0088] The above polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is (C5H8) n A hydrocarbon and its oxygen-containing derivative represented by the following composition, monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0089] Examples of the polyterpene resins mentioned above include pinene resin, limonene resin, dipentene resin, and pinene / limonene resin, which are made from the aforementioned terpene compounds. Among these, pinene resin is preferred because it is easy to polymerize and inexpensive because it is made from natural pine resin. Pinene resin usually contains both α-pinene and β-pinene, which are isomers of pinene, but it is classified into β-pinene resin, which is mainly composed of β-pinene, and α-pinene resin, which is mainly composed of α-pinene, depending on the difference in the components it contains.

[0090] Examples of the aromatically modified terpene resins mentioned above include terpene-phenol resins made from the above-mentioned terpene compounds and phenolic compounds, and terpene-styrene resins made from the above-mentioned terpene compounds and styreneic compounds. Alternatively, terpene-phenol-styrene resins made from the above-mentioned terpene compounds, phenolic compounds, and styreneic compounds can also be used. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of styreneic compounds include styrene and α-methylstyrene.

[0091] As the acrylic resin mentioned above, styrene-acrylic resins such as styrene-acrylic resin, which have carboxyl groups and are obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component, can be used. Among these, solvent-free carboxyl group-containing styrene-acrylic resins can be preferably used.

[0092] The above-mentioned solvent-free carboxyl group-containing styrene-acrylic resin is a (meth)acrylic resin (polymer) synthesized by high-temperature continuous polymerization (high-temperature continuous mass polymerization) (as described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3, pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials. In this specification, (meth)acrylic means methacrylic and acrylic.

[0093] Examples of acrylic monomer components constituting the above-mentioned acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives. Note that (meth)acrylic acid is a general term for acrylic acid and methacrylic acid. Examples of aromatic vinyl monomer components constituting the above-mentioned acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0094] In addition, other monomer components may be used as monomer components constituting the above-mentioned acrylic resin, along with (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

[0095] In the aforementioned rubber composition, the total content of resin (solid resin) and liquid plasticizer is preferably 60 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of rubber component, from the viewpoint of rigidity. The lower limit is not particularly limited, and resin and liquid plasticizer may not be included, but from the viewpoint of ice performance, etc., 5 parts by mass or more, and more preferably 7 parts by mass or more.

[0096] (f) Other materials (i) Anti-aging agents The rubber composition preferably contains an antioxidant from the viewpoint of crack resistance, ozone resistance, etc. The antioxidant is not particularly limited, but may 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, and N,N′-di-2-naphthyl-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as amines; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 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.

[0097] Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis.

[0098] The content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. A content above the lower limit tends to provide sufficient ozone resistance. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. A content below the upper limit tends to provide a good tire appearance.

[0099] (b) Stearic acid The rubber composition preferably contains stearic acid. The stearic acid content is preferably 0.5 to 10 parts by mass or more, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0100] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0101] (h) Zinc oxide The rubber composition preferably contains zinc oxide. The zinc oxide content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0102] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0103] (2) wax The rubber composition may contain wax. The wax is not particularly limited and includes petroleum-based waxes, natural waxes, and synthetic waxes obtained by refining or chemically treating multiple waxes. These waxes may be used individually or in combination of two or more types.

[0104] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Examples of natural waxes are not particularly limited as long as they are derived from non-petroleum resources, and include plant-based waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and whale wax; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof.

[0105] Commercially available products such as those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. can be used. The wax content should be set appropriately in terms of ozone resistance and cost.

[0106] (e) Sulfur The rubber composition preferably contains sulfur, as it forms appropriate cross-linked chains in the polymer chains and imparts good performance. The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. Good performance tends to be obtained by keeping the content within the above range.

[0107] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0108] (h) vulcanization accelerator The rubber composition preferably contains a vulcanization accelerator. The amount of vulcanization accelerator is not particularly limited and can be freely determined according to the desired vulcanization rate and crosslinking density, but is usually 0.3 to 10 parts by mass, preferably 0.5 to 7 parts by mass, per 100 parts by mass of the rubber component.

[0109] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These may be used individually or in combination of two or more. Among them, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

[0110] (T) Others In addition to the components mentioned above, the rubber composition may also contain other compounding agents commonly used in the tire industry, such as mold release agents.

[0111] (C) Use of sustainable materials In light of the strong demand for environmental protection in recent years, it is preferable to replace each material with sustainable materials such as those shown below when manufacturing each rubber composition.

[0112] (i) Rubber materials For example, the raw materials (monomers) for synthetic rubbers such as SBR and BR can be recycled from rubber products such as tires or non-rubber products such as polystyrene, instead of being derived from petroleum.

[0113] The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled butadiene and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene, and examples of aromatic vinyl include styrene, although these are not particularly limited. In particular, it is preferable to use recycled butadiene and / or recycled styrene as raw materials.

[0114] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0115] Furthermore, the raw materials (monomers) for synthetic rubbers such as SBR and BR may be derived from biomass. Biomass-derived monomers (biomass monomers) are not particularly limited and include biomass-derived butadiene and biomass-derived aromatic vinyls. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls are not particularly limited but include styrene. In addition, the method for producing biomass monomers is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of plants and animals. Typical biological conversions include fermentation by microorganisms, while chemical and / or physical conversions include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof. Examples of biomass sources for these monomers include sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0116] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0117] Furthermore, whether or not the polymer raw materials are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTMD6866-10.

[0118] pMC stands for Modern Standard Reference Carbon. 14 Sample relative to C concentration 14 This is the ratio of C concentrations, and this value is used as an indicator of the biomass ratio of the compound (rubber). The significance of this value is described below.

[0119] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14 Carbon dioxide is called a radioactive isotope, and its half-life is 5730 years, decreasing regularly. It takes 226,000 years for all of them to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed for more than 226,000 years after atmospheric carbon dioxide was taken in by plants, etc., it was initially contained within these materials. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0120] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere, and this is balanced by the decrease due to radioactive decay, resulting in a constant supply of C in the Earth's atmospheric environment. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 The values ​​are approximately in the range of mol%. Therefore, by using the difference between these values, it is possible to calculate the ratio (biomass ratio) of compounds derived from natural resources (compounds derived from biomass resources) in a given compound (rubber).

[0121] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0122] Therefore, if rubber is made from 100% biomass (natural) materials, it will have a value of approximately 110 pMC, although there are regional differences (currently, under normal conditions, it is often not 100). On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0123] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0124] (ii) Silica The silica can be derived from biological sources such as rice husks (for example, silica made from biomass materials such as rice husks), or it can be recycled silica from products containing silica.

[0125] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0126] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0127] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0128] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0129] These silicas may be used individually or in combination of two or more types. Using sustainable silica such as biomass silica or recycled silica is preferable from an environmental protection standpoint.

[0130] (iii) Carbon Black The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermally decomposing rubber products containing carbon black, such as waste tires (recycled carbon black). Using these sustainable carbon blacks is preferable from an environmental protection standpoint.

[0131] (iv) Moisturizer The softener may be derived from biomass, or from naphtha recycled from rubber or non-rubber products. Alternatively, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as a softener. Among these, softeners derived from biomass or recycled materials are preferred as sustainable softeners.

[0132] In addition, in the rubber composition, among the materials described above, the various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the compound of the present invention from carbon dioxide, carbon dioxide may be converted directly, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0133] 3. Tire manufacturing The tire according to this embodiment can be manufactured by conventional methods using the above-mentioned materials.

[0134] (1) Manufacturing of rubber compositions The rubber composition can be manufactured by known methods, for example, a manufacturing method that includes a base mixing step of mixing a rubber component and a filler, and a finish mixing step of mixing the mixture obtained in the base mixing step with a crosslinking agent.

[0135] Mixing can be carried out using known (closed) mixers such as Banbury mixers, kneaders, and open roll mixers.

[0136] The mixing temperature in the base mixing process is, for example, more than 50°C and less than 200°C, and the mixing time is, for example, more than 30 seconds and less than 30 minutes. In the base mixing process, in addition to the above components, compounding agents conventionally used in the rubber industry, such as softeners such as oils, zinc oxide, antioxidants, waxes, and vulcanization accelerators, may be added and mixed as needed.

[0137] In the final mixing step, the mixture obtained in the base mixing step and the crosslinking agent are mixed together. The mixing temperature in the final mixing step is, for example, above room temperature but below 80°C, and the mixing time is, for example, more than 1 minute but less than 15 minutes. In the final mixing step, in addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added and mixed as needed.

[0138] The rubber compositions obtained in the final mixing process are extruded into predetermined shapes to form the tread.

[0139] (2) Tire manufacturing Next, an inner liner, which is a component to ensure the airtightness of the tire, a carcass, which is a component to withstand the load, impact, and air pressure of the tire, and a belt, which is a component to tighten the carcass and increase the rigidity of the tread are wound onto the molding drum. The ends of the carcass ply are fixed to both sides of the edge, and beads, which are components to fix the tire to the rim, are placed there, and after forming it into a toroid shape, the tread is bonded to the center of the outer circumference and the sidewall is bonded to the radially outer side, thereby manufacturing an unvulcanized tire.

[0140] Subsequently, the unvulcanized tire obtained as described above is heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization process can be carried out by applying known vulcanization methods. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0141] The resulting tire exhibits improved performance on ice and wear resistance, making it suitable for use as a studless tire for passenger cars. [Examples]

[0142] The following are examples (examples) that are considered preferable for implementation, but the scope of the present invention is not limited to these examples.

[0143] We examined tires made from treads molded from the various compound materials listed below, as well as other rubber components, and the results calculated based on the evaluation methods described later regarding ice performance and wear resistance are shown in Tables 1 and 2.

[0144] 1. Manufacturing of rubber compositions First, the rubber composition that makes up the tread is manufactured.

[0145] (1) Compounding materials (a) Rubber component (i) NR (Natural Rubber): RSS#3 (b) BR (Butadiene rubber): BR150B manufactured by Ube Industries (95% cis by mass or more)

[0146] (b) Compounding materials other than rubber components (i) Carbon Black: Seast N220 manufactured by Tokai Carbon Co., Ltd. (b) Silica: UltraSil VN3 manufactured by Evonik Industries (N2SA:172m 2 / g) (h) Silane coupling agent: Si266 manufactured by Evonik Industries (ii) Water-soluble particles-1: MN-00 (magnesium sulfate) manufactured by Mai Chemical Industries Co., Ltd. (Median diameter: 75 μm) (e) Water-soluble particles-2: USN-00 (ultrafine magnesium sulfate) manufactured by Maiko Chemical Industries Co., Ltd. (Median diameter: 3 μm) (H) Water-soluble particles-3: Sodium sulfate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (Median diameter: 100 μm) (T) Liquid polymer: FB-823 manufactured by Kuraray Co., Ltd. (Liquid farnesene butadiene copolymer: farnesene / butadiene ratio = 80 / 20) (Glass transition temperature: -78°C, weight-average molecular weight: 50,000) (C) Acid-based functional group-containing conjugated diene polymer: LIR-410 manufactured by Kuraray Co., Ltd. (Carboxylate-modified isoprene polymer) (Glass transition temperature: -59°C, weight-average molecular weight: 30000) (Re) Wax: Ozo Ace wax manufactured by Nippon Seiro Co., Ltd. (Nu) Anti-aging agent: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (L) Oil: PS-32 (mineral oil) manufactured by Idemitsu Kosan Co., Ltd. (W) Stearic acid: NOF Corporation's bead stearic acid "Tsubaki" (W) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (c) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (Yo) Vulcanization accelerator: Noxellar NS manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0147] (Measurement of median diameter of water-soluble particles) The median diameter of each of the above water-soluble particles is measured by laser diffraction using a Shimadzu SALD-2000J. Specifically, the water-soluble particles are dispersed at room temperature in a mixed solution of dispersion solvent (toluene) and dispersant (10% by mass sodium di-2-ethylhexyl sulfosuccinate / toluene solution). The resulting dispersion is stirred for 5 minutes while irradiating it with ultrasound to obtain a test solution. The test solution is then transferred to a batch cell and measured after 1 minute (refractive index: 1.70-0.20i).

[0148] (2) Manufacturing of rubber composition Next, according to the formulations shown in Tables 1 and 2, natural rubber and silica, and butadiene rubber and silica were added using a 1.7L Banbury mixer, and each mixture was kneaded at 150°C for 3 minutes to obtain a masterbatch. Note that the amounts of each ingredient are in parts by mass.

[0149] Next, the materials other than sulfur and vulcanization accelerator are added to the obtained masterbatch and kneaded at 150°C for 2 minutes to obtain a kneaded product.

[0150] Next, sulfur and a vulcanization accelerator are added, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain a rubber composition.

[0151] 2. Tire manufacturing (1) Tread manufacturing Next, the rubber composition is extruded into a predetermined shape to manufacture the tread.

[0152] (2) Tire manufacturing

[0153] Subsequently, the tire components are bonded together to form an unvulcanized tire, which is then press-vulcanized for 15 minutes under conditions of 170°C to produce the test studless tires (tire size: 195 / 65R15) for each of Examples 1-8 and Comparative Examples 1-5.

[0154] (3) Calculation of parameters In parallel, the total mass A (g) of water-soluble particles was determined from the amount of water-soluble particles blended (parts by mass) and the mass of the tread rubber (g), and the actual contact area B (cm²) of each test studless tire was also determined. 2 First, calculate (A / B), and then calculate (A / B).

[0155] 3. Performance evaluation test Next, each test studless tire is stored in a dark place at room temperature for three months, after which the following evaluation tests are performed.

[0156] (1) Ice performance Each test studless tire is mounted on a domestically produced 2000cc FR vehicle, and the vehicle is driven under ambient temperatures of 0 to -5°C. The stopping distance on ice is measured when the vehicle is brought to a complete stop at a speed of 30 km / h with the lock brake applied.

[0157] Next, using the stopping distance of Comparative Example 1 as the "evaluation standard," the results of each test studless tire are indexed based on the following formula to evaluate their ice performance. A higher numerical value indicates a shorter stopping distance and superior ice performance. Ice performance = [(Stopping distance of Comparative Example 1) / (Stopping distance of test studless tire)] × 100

[0158] (2) Abrasion resistance The performance of the test studless tires will be evaluated under the following conditions. The test tires will be mounted on all wheels of a domestic 2000cc front-wheel-drive vehicle, inflated to an internal pressure of 230kPa, and driven for 50,000km under ambient temperatures of 0 to -5°C, and the amount of wear on the tread will be measured.

[0159] Next, using the wear amount of Comparative Example 2 as the "evaluation standard," the results of each test studless tire are indexed based on the following formula to evaluate wear resistance. A higher numerical value indicates less wear and superior wear resistance. Wear resistance = [(Wear amount of Comparative Example 2) / (Wear amount of test studless tire)] × 100

[0160] (3) Overall evaluation The results of the ice performance evaluation and the wear resistance evaluation are then combined to arrive at an overall evaluation.

[0161] [Table 1]

[0162] [Table 2]

[0163] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0164] The present invention (1) is, A tire having a tread, The aforementioned tread is The tire rubber composition contains isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles. The total mass A (g) of the water-soluble particles in the tread and the actual contact area B (cm²) of the tread. 2 This tire is characterized by having a ratio (A / B) of 0.60 or greater.

[0165] The present invention (2) is, The tire is characterized in that the (A / B) ratio is 0.64 or greater, as described in (1) of the present invention.

[0166] The present invention (3) is, The tire according to (1) or (2) of the present invention, characterized in that the acidic functional group is at least one of a carboxyl group, a sulfate group, a phosphate group, a hydroxyphenyl group, or an acidic functional group derived therefrom.

[0167] The present invention (4) is, The aforementioned conjugated diene polymer is characterized by having a weight-average molecular weight of 100,000 or less in terms of styrene, determined by gel permeation chromatography (GPC), and is a tire in any combination with any of the present invention (1) to (3).

[0168] The present invention (5) is, The tire is characterized in that the content of the conjugated diene polymer is 5 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component, and is any combination of the tire with any of the present invention (1) to (4).

[0169] The present invention (6) is, The tire is characterized in that the content of the conjugated diene polymer is 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component, and is any combination of the tire with any of the present invention (1) to (5).

[0170] The present invention (7) is, The tire is characterized in that the content of the water-soluble particles is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, and is any combination of the tire with any of the present invention (1) to (6).

[0171] The present invention (8) is, The water-soluble particles are characterized by being at least one of sulfates, chlorides, carbonates, and phosphates, and the tire is any combination of any of the present invention (1) to (7).

[0172] The present invention (9) is, The tire is characterized in that the median diameter (D50) of the water-soluble particles is 1 μm or more and 1 mm or less, and is any combination of any of the present invention (1) to (8).

[0173] The present invention (10) is, The tire is characterized in that the median diameter (D50) of the water-soluble particles is 2 μm or more and 500 μm or less, as described in (9) of the present invention.

[0174] The present invention (11) is, The tire is characterized in that the content ratio of the isoprene-based rubber in the rubber component is 10% by mass or more and 70% by mass or less, and is any combination with any of the present invention (1) to (10).

[0175] The present invention (12) is, The tire is characterized in that the content ratio of the conjugated diene rubber in the rubber component is 30% by mass or more and 90% by mass or less, and is any combination with any of the present invention (1) to (11).

[0176] The present invention (13) is, The aforementioned conjugated diene rubber is characterized by having a cis content of 80% by mass or more, and is a tire in any combination with any of the present invention (1) to (12).

[0177] The present invention (14) is, The present invention is characterized by being a studless tire and is a tire in any combination with any of the present inventions (1) to (13).

[0178] The present invention (15) is, A tire rubber composition for forming the tread of a tire according to any of the present invention (1) to (14), This tire rubber composition is characterized by containing isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles.

Claims

1. A tire having a tread, The aforementioned tread is The tire rubber composition contains isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles. The total mass A (g) of the water-soluble particles in the tread and the actual contact area B (cm²) of the tread. ２ A tire characterized in that the ratio (A / B) of ) is 0.60 or greater.

2. The tire according to claim 1, characterized in that the (A / B) ratio is 0.64 or greater.

3. The tire according to claim 1, characterized in that the acidic functional group is at least one of a carboxyl group, a sulfate group, a phosphate group, a hydroxyphenyl group, or an acidic functional group derived therefrom.

4. The tire according to claim 1, characterized in that the conjugated diene polymer has a weight-average molecular weight in terms of styrene, determined by gel permeation chromatography (GPC), of 100,000 or less.

5. The tire according to claim 1, characterized in that the content of the conjugated diene polymer is 5 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the rubber component.

6. The tire according to claim 5, characterized in that the content of the conjugated diene polymer is 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component.

7. The tire according to claim 1, characterized in that the content of the water-soluble particles is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component.

8. The tire according to claim 1, characterized in that the water-soluble particles are at least one of sulfates, chlorides, carbonates, and phosphates.

9. The tire according to claim 1, characterized in that the median diameter (D50) of the water-soluble particles is 1 μm or more and 1 mm or less.

10. The tire according to claim 9, characterized in that the median diameter (D50) of the water-soluble particles is 2 μm or more and 500 μm or less.

11. The tire according to claim 1, characterized in that the content ratio of the isoprene-based rubber in the rubber component is 10% by mass or more and 70% by mass or less.

12. The tire according to claim 1, characterized in that the content ratio of the conjugated diene rubber in the rubber component is 30% by mass or more and 90% by mass or less.

13. The tire according to claim 1, characterized in that the conjugated diene rubber has a cis content of 80% by mass or more.

14. The tire described in item 1, characterized in that it is a studless tire.

15. A tire rubber composition for forming the tread of a tire according to any one of claims 1 to 14, A rubber composition for tires, characterized by containing isoprene-based rubber and conjugated diene-based rubber as rubber components, as well as a conjugated diene-based polymer having acidic functional groups and water-soluble particles.

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