Rubber compositions and tires

Abstract

The present invention aims to provide a rubber composition and a tire that provide improved overall performance in terms of wet and dry grip performance. The present invention relates to a rubber composition having a dynamic modulus E* that reversibly changes with water and satisfying the following relation (1): dynamic modulus E* when wet with water / dynamic modulus E* when dry x 100% ≤ 90% (1).

Description

Technical Field

[0001] This invention relates to rubber compositions and tires. Background Technology

[0002] In recent years, safety has become an increasingly important issue for all motor vehicles. This has created a demand for further improvements in wet grip performance. To date, a wide variety of studies have been conducted to improve wet grip performance, and numerous inventions involving rubber compositions containing silica have been reported (e.g., Patent Document 1). Wet grip performance can be greatly affected by the properties of the rubber composition, particularly in the tread portion, which is in contact with the road. Therefore, various technical improvements in rubber compositions for tire components (such as the tread) have been proposed and put into practical use.

[0003] [List of cited references]

[0004] [Patent Literature]

[0005] Patent Document 1: JP 2008-285524 A Summary of the Invention

[0006] [Technical Issues]

[0007] As a result of extensive research, the inventors have discovered that although the wet grip performance of tires has been greatly improved through technical improvements to tread rubber compositions containing silica, there is still an important technical challenge of changes in grip performance (caused by changes in road conditions, such as from dry roads to wet roads or from wet roads to dry roads), and therefore there is room for improvement.

[0008] After in-depth research into this problem, the inventors discovered that when traditional rubber compounds are changed from a dry state (never wetted with water) to a so-called wet state (wetted with water), their dynamic modulus does not change or they harden due to water cooling. Therefore, the road contact area decreases, resulting in a tendency for wet grip performance to be lower compared to dry grip performance.

[0009] Therefore, it has been found that traditional technologies still have room for improvement in terms of the overall performance of wet grip and dry grip.

[0010] The purpose of this invention is to solve the above-mentioned problems and to provide a rubber composition and tire that provides improved overall performance in terms of wet grip and dry grip.

[0011] [Problem-solving methods]

[0012] This invention relates to a rubber composition having a dynamic modulus E* that changes reversibly with water and satisfies the following relationship (1):

[0013] The dynamic modulus E* when wetted / the dynamic modulus E* when dry × 100% ≤ 90% (1).

[0014] Preferably, the relationship (1) is as follows: dynamic modulus E* when wetted / dynamic modulus E* when dry × 100% ≤ 85%, more preferably ≤ 80%, and even more preferably ≤ 75%.

[0015] Preferably, the rubber composition comprises diene rubber and polymers having carbon-carbon double bonds and heteroatoms.

[0016] Preferably, the heteroatom is at least one atom selected from oxygen, nitrogen, silicon, sulfur, phosphorus and halogen atoms.

[0017] Preferably, the polymer contains at least 5% by mass of insoluble matter when suspended in 10 mL of water in an amount of 1 g.

[0018] Preferably, the polymer contains at least 5% by mass of insoluble matter when suspended in 10 mL of tetrahydrofuran at a concentration of 1 g.

[0019] Preferably, the rubber composition comprises at least 5 parts by weight of polymer relative to 100 parts by weight of the rubber component in the rubber composition.

[0020] Preferably, the rubber composition comprises isoprene-based rubber.

[0021] Preferably, the rubber composition comprises polybutadiene rubber.

[0022] Preferably, the styrene-butadiene rubber content of the rubber composition is 95% or less, based on the rubber component of the rubber composition as 100% by mass.

[0023] Preferably, the rubber composition is used for the tire tread.

[0024] The present invention also relates to a tire having tire components that at least partially comprise the rubber composition.

[0025] Preferably, the tire component is the tread.

[0026] [Beneficial effects of the present invention]

[0027] The rubber composition of the present invention has a dynamic modulus that changes reversibly with water and satisfies the above-mentioned relationship (1). This rubber composition provides improved overall performance in terms of both wet and dry grip. Detailed Implementation

[0028] The rubber composition of the present invention has a dynamic modulus E* that changes reversibly with water and satisfies the following relationship (1). Therefore, the rubber composition provides improved overall performance in terms of both wet and dry grip.

[0029] Dynamic modulus E* when wetted / Dynamic modulus E* when dry × 100% ≤ 90% (1)

[0030] The above-described rubber composition exhibits the aforementioned effects. The reasons for these effects are not entirely clear, but can be explained as follows.

[0031] The rubber composition of the present invention has a dynamic modulus E* that changes reversibly with water and also satisfies the above-described relationship (1). The above-described relationship (1) indicates that the dynamic modulus E* when wetted with water is less than the dynamic modulus E* when dry, wherein each dynamic modulus E* represents the dynamic modulus E* at a frequency of 10 Hz and a temperature of 0 °C. In other words, "the rubber composition of the present invention has a dynamic modulus E* that changes reversibly with water and also satisfies the above-described relationship (1)" means that the dynamic modulus E* of the rubber composition is lower when wetted with water than when dry, and changes reversibly in the presence of water.

[0032] Therefore, when road conditions change from dry to wet, the rubber composition becomes wetted and thus has a reduced dynamic modulus E*. This allows it to minimize the decrease in grip performance (wet grip) and achieve good grip performance (wet grip). This is because if the dynamic modulus E* remains suitable for dry roads, sufficient grip performance cannot be obtained on wet roads where slippage is more likely; conversely, the reduced dynamic modulus E* leads to an increase in road contact area, which in turn minimizes the decrease in grip performance (wet grip) and achieves good grip performance (wet grip).

[0033] On the other hand, as road conditions change from wet to dry, the water-wet rubber composition dries and thus has an increased dynamic modulus E*. This allows it to reduce the decrease in grip performance (dry grip performance) and achieve good grip performance (dry grip performance). This is because if the dynamic modulus E* remains suitable for wet roads, sufficient grip performance cannot be obtained on dry roads where slippage is unlikely; conversely, the increased dynamic modulus E* (which is suitable for dry roads) allows it to reduce the decrease in grip performance (dry grip performance) and achieve good grip performance (dry grip performance).

[0034] Therefore, a rubber composition having a dynamic modulus E* that changes reversibly with water and also satisfies the above relationship (1) can provide an appropriate dynamic modulus E* depending on the moisture conditions on the road (wet or dry road), thereby providing improved overall performance in terms of wet grip and dry grip.

[0035] Therefore, the rubber composition of the present invention, having a dynamic modulus E* that changes reversibly with water and satisfying the above-mentioned relationship (1), provides improved overall performance in terms of wet grip and dry grip.

[0036] In this article, the dynamic modulus E* and tanδ of the rubber composition refer to the dynamic modulus E* and tanδ of the vulcanized rubber composition, respectively. Furthermore, tanδ is determined by viscoelasticity testing of the vulcanized rubber composition.

[0037] In this text, the phrase "dynamic modulus E* that changes reversibly with water" refers to the dynamic modulus E* of a (vulcanized) rubber composition that increases or decreases reversibly in the presence of water. It is sufficient that the dynamic modulus E* changes reversibly when the state of the rubber composition changes, for example, as described below: drying → water wetting → drying. Here, the rubber composition in the previous dried state may or may not have the same dynamic modulus E* as in the subsequent dried state.

[0038] In this document, the term "dynamic modulus E* at dry" refers to the dynamic modulus E* of a (vulcanized) rubber composition in a dry state, specifically, the dynamic modulus E* of a (vulcanized) rubber composition after drying using the methods described in the examples.

[0039] In this document, the term "dynamic modulus E* when wetted with water" refers to the dynamic modulus E* of a (vulcanized) rubber composition in a water-wetted state, specifically, the dynamic modulus E* of a (vulcanized) rubber composition wetted with water as described in the examples.

[0040] In this paper, the dynamic modulus E* of the (vulcanized) rubber composition was measured on a test vulcanized rubber sheet using a spectrometer (Uejima Manufacturing Co., Ltd.) at a strain of 2%, a frequency of 10 Hz, and a temperature of 0 °C.

[0041] In this document, the term "tanδ at 70°C when dried" refers to the tanδ of a (vulcanized) rubber composition in a dried state at 70°C, specifically, the tanδ of a (vulcanized) rubber composition dried by the method described in the examples at 70°C.

[0042] In this article, tanδ of the (vulcanized) rubber composition at 70°C represents the loss tangent measured at 70°C, 10% initial strain, 2% dynamic strain, and a frequency of 10 Hz.

[0043] As shown in the above relationship (1), the value of "dynamic modulus E* when wetted / dynamic modulus E* when dry" [(dynamic modulus E* of the (vulcanized) rubber composition in the wetted state) / (dynamic modulus E* of the (vulcanized) rubber composition in the dry state) × 100%] is 90% or less, preferably 89% or less, more preferably 88% or less, even more preferably 87% or less, particularly preferably 86% or less, most preferably 85% or less, further preferably 83% or less, further preferably 80% or less, further preferably 77% or less, further preferably 75% or less, further preferably 73% or less, further preferably 70% or less, and further preferably 65% ​​or less. The lower limit is not particularly limited, but it is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, particularly preferably 35% or more, most preferably 40% or more, even more preferably 50% or more, and even more preferably 60% or more. When this value is within the above range, beneficial effects can be more appropriately achieved.

[0044] The "dynamic modulus E* under dry conditions" (the dynamic modulus E* of the (vulcanized) rubber composition in the dry state) can be appropriately adjusted within the range satisfying the above relationship (1). It is preferably 5 MPa or more, more preferably 6 MPa or more, even more preferably 7 MPa or more, particularly preferably 8 MPa or more, most preferably 9 MPa or more, even more preferably 10 MPa or more, further preferably 20 MPa or more, but preferably 200 MPa or less, more preferably 190 MPa or less, even more preferably 180 MPa or less, particularly preferably 170 MPa or less, most preferably 160 MPa or less, even more preferably 150 MPa or less, further most preferably 100 MPa or less, especially most preferably 80 MPa or less, further preferably 60 MPa or less, further preferably 40 MPa or less, further preferably 28 MPa or less, further preferably 24 MPa or less, further preferably 23 MPa or less, and further preferably 22 MPa or less. When the dynamic modulus E* is within the above range, beneficial effects can be more appropriately achieved.

[0045] The "dynamic modulus E* under water wetting" (dynamic modulus E* of the (vulcanized) rubber composition in the water-wetting state) can be appropriately adjusted within the range satisfying the above relationship (1). It is preferably 5 MPa or more, more preferably 6 MPa or more, even more preferably 7 MPa or more, particularly preferably 8 MPa or more, most preferably 9 MPa or more, even more preferably 10 MPa or more, further preferably 14 MPa or more, even more preferably 100 MPa or less, more preferably 90 MPa or less, even more preferably 80 MPa or less, particularly preferably 70 MPa or less, most preferably 60 MPa or less, even more preferably 55 MPa or less, further preferably 50 MPa or less, especially preferably 40 MPa or less, further preferably 30 MPa or less, further preferably 25 MPa or less, further preferably 21 MPa or less, further preferably 20 MPa or less, further preferably 19 MPa or less, further preferably 17 MPa or less, further preferably 16 MPa or less, and further preferably 15 MPa or less. When the dynamic modulus E* is within the above range, the beneficial effects can be achieved more appropriately.

[0046] Preferably, the above rubber composition satisfies the following relationship (2). This provides good fuel economy.

[0047] When dried at 70℃, tanδ < 0.14(2)

[0048] In the above relationship, tanδ at 70℃ represents the loss tangent measured at 70℃, 10% initial strain, 2% dynamic strain, and 10Hz frequency.

[0049] As shown in equation (2) above, the tanδ at 70°C when dry (tanδ of the (vulcanized) rubber composition in the dry state at 70°C) is preferably less than 0.14, preferably less than 0.13, more preferably less than 0.12, and even more preferably less than 0.11. The lower limit is not particularly limited, but it is preferably 0.01 or more, more preferably 0.02 or more. When this tanδ is within the above range, beneficial effects can be more appropriately achieved.

[0050] A rubber composition in which the dynamic modulus E* varies reversibly with water as shown in Equation (1) above can be obtained by adding a compound that can form reversible molecular bonds (e.g., hydrogen bonds or ionic bonds) with water. More specifically, when the rubber composition comprises a rubber component containing diene rubber and a polymer having carbon-carbon double bonds and heteroatoms, the rubber composition achieves the dynamic modulus E* varying reversibly with water as shown in Equation (1) above. This is because heteroatoms can form reversible molecular bonds (e.g., hydrogen bonds or ionic bonds) with water in the rubber composition, resulting in a decrease in the dynamic modulus E* of the rubber composition in the water-wetted state.

[0051] Furthermore, due to the aforementioned combination, the polymer is cross-linked with the rubber component during vulcanization via its carbon-carbon double bonds, thereby becoming fixed to the rubber component. This allows for the suppression of polymer release from the rubber component, thus inhibiting polymer precipitation on the rubber surface. Consequently, the reduction in grip performance (wet grip performance, dry grip performance) can also be reduced.

[0052] The tanδ at 70°C during drying can be adjusted by the type and amount of chemicals added to the rubber composition (especially rubber components, fillers, softeners, sulfur, vulcanization accelerators, and silane coupling agents). The tanδ at 70°C tends to decrease, for example, by using a softener highly compatible with the rubber components, using modified rubber, using silica as a filler, reducing the amount of oil as a plasticizer, increasing the amount of sulfur, increasing the amount of vulcanization accelerator, or increasing the amount of silane coupling agent.

[0053] The dynamic modulus E* at dryness can be adjusted by the type and amount of chemicals added to the rubber composition (especially rubber components, fillers, and softeners such as oils). For example, the dynamic modulus E* at dryness tends to decrease by increasing the amount of softener; it tends to increase by increasing the amount of filler; and it tends to decrease by decreasing the amount of sulfur. Furthermore, the dynamic modulus E* at dryness can also be adjusted by changing the amounts of sulfur and vulcanization accelerators. More specifically, increasing the amount of sulfur tends to increase the dynamic modulus E* at dryness, while increasing the amount of vulcanization accelerator tends to increase the dynamic modulus E* at dryness.

[0054] More specifically, when the dynamic modulus E* during drying is adjusted to the desired range, and the rubber component containing diene rubber is further combined with a polymer having carbon-carbon double bonds and heteroatoms, the rubber composition achieves a dynamic modulus E* that varies as shown in the above relationship (1) and changes reversibly with water, while providing tanδ at 70°C during drying adjusted to the desired range.

[0055] As another means to achieve a dynamic modulus E* of a rubber composition that varies reversibly with water as shown in Equation (1) above, when the rubber composition comprises a combination of a rubber component containing a diene rubber and a polymer having carbon-carbon double bonds and heteroatoms, the polymer is crosslinked with the rubber component through its carbon-carbon double bonds during vulcanization, thereby immobilizing it on the rubber component. This allows for the suppression of polymer release from the rubber component, enabling the rubber composition to achieve a dynamic modulus E* that varies reversibly with water as shown in Equation (1) above.

[0056] If the polymer does not have carbon-carbon double bonds, it may be released into the water when the rubber composition comes into contact with water, and therefore a reversible change in dynamic modulus may not occur.

[0057] As another means of adjusting the tanδ at 70°C during drying to within the aforementioned range, when the rubber composition comprises a combination of a rubber component containing a diene-based rubber and a polymer having carbon-carbon double bonds and heteroatoms, the polymer is crosslinked with the rubber component through its carbon-carbon double bonds during vulcanization, thereby immobilizing it on the rubber component. This allows for the suppression of polymer release from the rubber component, thereby reducing the tanδ at 70°C.

[0058] Another means of achieving a dynamic modulus in a rubber composition that varies reversibly with water, as shown in Equation (1) above, is as follows: for example, by reversibly breaking or reforming the ionic bonds between rubber molecules through the addition of water or drying. More specifically, when the rubber composition comprises a combination of a rubber containing halogens or oxygen and a compound containing metals, metalloids, or nitrogen, the rubber composition achieves a dynamic modulus that varies reversibly with water, as shown in Equation (1) above. This is because, according to the above combination, cations from metals, metalloids, or nitrogen and anions from halogens or oxygen form ionic bonds between rubber molecules. These ionic bonds are then broken by the addition of water and reformed by the drying of water, resulting in a decrease in the dynamic modulus when wetted and an increase when dried.

[0059] The chemicals that can be used are listed below.

[0060] Examples of rubber components include diene-based rubbers, such as isoprene-based rubbers, polybutadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). The rubber component may contain a single type of rubber or a combination of two or more rubbers. Among these, diene-based rubbers are preferred, with isoprene-based rubbers, BR, and SBR being more preferred, and SBR being even more preferred. Combinations of isoprene-based rubbers and SBR, combinations of BR and SBR, or combinations of isoprene-based rubbers, BR, and SBR are also preferred.

[0061] The weight-average molecular weight (Mw) of the rubber component is preferably 150,000 or more, more preferably 350,000 or more. There is no particular upper limit to Mw, but it is preferably 4,000,000 or less, more preferably 3,000,000 or less.

[0062] Based on 100% by mass of rubber composition, the amount of diene rubber is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, most preferably 90% by mass or more, and may be 100% by mass. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0063] SBR is not particularly limited. Examples include those commonly used in the tire industry, such as emulsion polymerization SBR (E-SBR) and solution polymerization SBR (S-SBR). These can be used alone or in combination of two or more.

[0064] The styrene content of the SBR is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the styrene content is within the above range, it tends to achieve beneficial effects more appropriately.

[0065] The vinyl content of the SBR is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, most preferably 50% by mass or more, and even more preferably 75% by mass or less, more preferably 65% ​​by mass or less. SBRs with vinyl content within the above range tend to have good compatibility with BRs, making it easier to achieve beneficial effects.

[0066] SBR can be either unmodified SBR or modified SBR.

[0067] Modified SBR can be any SBR having functional groups that interact with fillers (such as silica). For example, it can be: a chain-end modified SBR obtained by modifying at least one chain end of the SBR with a compound (modifier) ​​having the aforementioned functional groups (i.e., a chain-end modified SBR capped with the aforementioned functional groups); a main-chain modified SBR having the aforementioned functional groups in the main chain; a main-chain-chain-end modified SBR having the aforementioned functional groups in both the main chain and the chain ends (e.g., a main-chain-chain-end modified SBR having the aforementioned functional groups in the main chain and at least one chain end modified with the aforementioned modifier); or a chain-end modified SBR that has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule to introduce hydroxyl or epoxy groups. These can be used alone or in combination of two or more.

[0068] Examples of the aforementioned functional groups include: amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazo, urea, ether, carbonyl, oxocarbonyl, mercapto, sulfide group, disulfide group, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazogroup, azo, diazo, carboxyl, nitrile group, pyridyl, alkoxy, hydroxy, oxygen, and epoxy. These functional groups can be substituted. Among these, amino (preferably an amino group in which the hydrogen atom of the amino group is substituted by a C1-C6 alkyl group), alkoxy (preferably C1-C6 alkoxy), alkoxysilyl (preferably C1-C6 alkoxysilyl), and amide.

[0069] SBR can be manufactured or sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, or Zeon Corporation.

[0070] Based on a rubber composition of 100% by mass, the amount of SBR is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0071] BR is not specifically limited. Examples include those commonly used in the tire industry. These can be used alone or in combination of two or more.

[0072] The cis content of BR is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 97% by mass or more. There is no particular upper limit to this cis content, and it can be 100% by mass. When the cis content is within the above range, it tends to more appropriately achieve the beneficial effects.

[0073] BR can be unmodified BR or modified BR. Examples of modified BR include those modified BRs incorporating the aforementioned functional groups. Preferred embodiments are as described with respect to the modified SBR described above.

[0074] BR can be a commercially available product from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, or Zeon Corporation.

[0075] Based on 100% by mass of rubber composition, the amount of BR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 70% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. When this amount is within the above range, it tends to achieve the beneficial effects more appropriately.

[0076] Examples of isoprene-based rubbers include natural rubber (NR), polyisoprene rubber (IR), refined NR, modified NR, and modified IR. NR can be any type of NR commonly used in the tire industry, such as SIR20, RSS#3, or TSR20. Non-limiting examples of IR include those commonly used in the tire industry, such as IR2200. Examples of refined NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized polyisoprene rubber, hydrogenated polyisoprene rubber, and grafted polyisoprene rubber. These can be used alone or in combination of two or more. Of these, NR is preferred.

[0077] Based on 100% by mass of rubber composition, the amount of isoprene-based rubber is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 60% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less. When this amount is within the above range, it tends to achieve beneficial effects more appropriately.

[0078] In this study, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by gel permeation chromatography (GPC) calibrated with polystyrene standards (GPC-8000 series from Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M from Tosoh Corporation).

[0079] The cis content (cis-1,4-butadiene unit content) and vinyl content (1,2-butadiene unit content) can be determined by infrared absorption spectroscopy. Styrene content can be determined by... 1 H-NMR analysis was performed.

[0080] The rubber composition described above preferably contains a polymer having carbon-carbon double bonds and heteroatoms. More preferably, the rubber composition contains diene rubber and a polymer having carbon-carbon double bonds and heteroatoms.

[0081] Carbon-carbon double bonds are essential for crosslinking with diene-based rubbers. There is no particular limitation on the number of such bonds.

[0082] The term "heteroatom" refers to an atom other than carbon and hydrogen atoms. It can be any heteroatom capable of forming reversible molecular bonds (e.g., hydrogen bonds or ionic bonds) with water. The heteroatom is preferably at least one atom selected from oxygen, nitrogen, silicon, sulfur, phosphorus and halogen atoms, more preferably at least one atom selected from oxygen, nitrogen and silicon atoms, and even more preferably oxygen atoms.

[0083] Therefore, the rubber composition preferably comprises a diene rubber and a polymer having a carbon-carbon double bond and at least one atom selected from oxygen, nitrogen, silicon, sulfur, phosphorus, and halogen atoms. More preferably, the rubber composition comprises a diene rubber and a polymer having a carbon-carbon double bond and at least one atom selected from oxygen, nitrogen, and silicon atoms. Even more preferably, the rubber composition comprises a diene rubber and a polymer having a carbon-carbon double bond and oxygen atoms. Furthermore, heteroatoms are preferably present in the main chain (backbone) of the polymer, and more preferably in the repeating units of the polymer.

[0084] Examples of structures or groups having an oxygen atom include: ether groups, ester groups, carboxyl groups, carbonyl groups, alkoxy groups, and hydroxyl groups. Among these, ether groups are preferred, and oxidized alkenyl groups are more preferred.

[0085] Examples of structures or groups having a nitrogen atom include: amino groups (primary, secondary, and tertiary amino groups), amide groups, cyano groups, and nitro groups. Among these, amino groups are preferred, and tertiary amino groups are more preferred.

[0086] Examples of structures or groups having silicon atoms include: silyl, alkoxysilyl, and silanol groups. Among these, silyl is preferred, and alkoxysilyl is more preferred.

[0087] Examples of structures or groups having sulfur atoms include: thioether group, sulfate group and sulfonyl group, and sulfate ester.

[0088] Examples of structures or groups containing phosphorus atoms include: phosphate groups and phosphate esters.

[0089] Examples of structures or groups having halogen atoms include halogen groups, such as fluorine, chlorine, bromine, and iodine groups.

[0090] The term "oxide-alkenyl" refers to a group represented by -(AO)-, preferably -(AO). n - represents a group, where n represents the number of repeating units.

[0091] The number of carbon atoms in the alkylene A of the oxidized alkenyl AO is preferably 1 or more, more preferably 2 or more, further preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. When the number of carbon atoms is within the above range, it tends to achieve the beneficial effects more appropriately.

[0092] The alkylene A in the oxidized alkenyl AO can be straight-chain or branched, but is preferably branched to form a large-volume structure, thereby more appropriately achieving the beneficial effects.

[0093] To more effectively achieve the desired results, AO is preferably C2-C3 oxidized alkenyl (oxidized vinyl (EO), oxidized propylene (PO)) or attached to the branched R 4 (R 4 The C2-C3 oxidized alkenyl group (which may optionally have heteroatoms) on a hydrocarbon group, more preferably a C2-C3 oxidized alkenyl group and a branched R group 4 The combination of C2-C3 oxidized alkenyl groups. Branched R 4 It is preferably attached to a carbon atom adjacent to an oxygen atom.

[0094] As R 4 The hydrocarbon group optionally having heteroatoms is not particularly limited. The number of carbon atoms in the hydrocarbon group is preferably 1 or more, more preferably 2 or more, even more preferably 10 or less, more preferably 6 or less, and still more preferably 4 or less. When the number of carbon atoms is within the above range, it tends to achieve the beneficial effect more appropriately.

[0095] As R 4 Preferred examples of hydrocarbon groups that optionally have heteroatoms are groups represented by the following formula.

[0096] ——CH2-O-CH2-CH=CH2

[0097] The group represented by -(AO)- more preferably includes the group represented by formula (B), and particularly preferably includes the groups represented by formulas (A) and (B), optionally combined with the group represented by formula (C).

[0098]

[0099] When the above polymer has at least two types of oxidized alkenyl groups, the oxidized alkenyl groups can be block-arranged or randomly arranged.

[0100] The polymer described above is preferably a polymer having the groups (structural units) shown in formula (B), and more preferably a polymer having the groups (structural units) shown in formulas (A) and (B).

[0101] The amount of the group (structural unit) shown in formula (B) is preferably 2 mol% or more, more preferably 5 mol% or more, even more preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less, based on 100 mol% of the polymer.

[0102] The weight-average molecular weight (Mw) of the polymer is preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, particularly preferably 500,000 or more, further preferably 3,000,000 or less, more preferably 2,500,000 or less, even more preferably 2,000,000 or less, particularly preferably 1,500,000 or less, and most preferably 1,000,000 or less.

[0103] When the polymer is suspended in 10 mL of water at a concentration of 1 g, it preferably contains at least 5% by mass, more preferably at least 10% by mass, even more preferably at least 30% by mass, particularly preferably at least 50% by mass, most preferably at least 70% by mass, even more preferably at least 80% by mass, and further most preferably at least 90% by mass of insoluble matter (water-insoluble matter). There is no particular upper limit to the amount of such insoluble matter.

[0104] The amount of this insoluble matter can be determined as described in the examples.

[0105] The greater the amount of this insoluble matter, the less the polymer dissolves in water when the rubber compound is wetted with water, thus allowing for a more suitable reversible change in dynamic modulus.

[0106] When the polymer is suspended in 10 mL of tetrahydrofuran in an amount of 1 g, it preferably contains at least 5% by mass, more preferably at least 10% by mass, even more preferably at least 30% by mass, particularly preferably at least 50% by mass, most preferably at least 70% by mass, and even most preferably at least 90% by mass of an insoluble substance (THF-insoluble substance). There is no particular upper limit to the amount of such insoluble substance.

[0107] The amount of this insoluble matter can be determined as described in the examples.

[0108] Because diene rubbers are soluble in tetrahydrofuran, polymers containing a large amount of insoluble matter in tetrahydrofuran have low compatibility with diene rubbers. Therefore, they tend to achieve a full reduction in dynamic modulus when wetted with water.

[0109] The polymers described above may be commercially available. Alternatively, the polymers may be manufactured by preparing polymers from monomers having heteroatoms.

[0110] Monomers containing heteroatoms are not particularly limited. Examples of monomers containing oxygen atoms include: ethers, such as vinyl ethers, alkoxystyrene, allyl glycidyl ether, ethylene oxide, propylene oxide, and tetrahydrofuran; (meth)acrylic acid and their esters or anhydrides. Examples of monomers containing nitrogen atoms include: acrylonitrile, N-vinylcarbazole, carbamic acid, and caprolactam. Examples of monomers containing silicon atoms include: alkoxysilylstyrene and alkoxysilylvinyl monomers.

[0111] When a monomer with heteroatoms does not have unsaturated bonds, the monomer with heteroatoms can be polymerized together with a monomer with carbon-carbon double bonds (e.g., conjugated diene monomers (e.g., butadiene or isoprene) or vinyl polymers (e.g., styrene)).

[0112] Aggregation methods can be performed using any method (including known methods).

[0113] Relative to 100 parts by mass of the rubber component, the amount of polymer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, most preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, further most preferably 60 parts by mass or more, especially most preferably 70 parts by mass or more, and even more preferably 150 parts by mass or less, more preferably 100 parts by mass or less. When this amount is within the above range, it tends to achieve better beneficial effects.

[0114] The above-mentioned rubber composition may contain silicon dioxide.

[0115] Examples of silica include dry silica (silicic anhydride) and wet silica (hydrated silicic acid). Wet silica is preferred because it contains a large number of silanol groups. These can be used alone or in combination of two or more.

[0116] The nitrogen adsorption specific surface area (N2SA) of silica is 40 m². 2 / g or more, preferably 60m 2 / g or more, preferably 80m 2 / g or more, and more preferably 160m 2 / g or more. Furthermore, the N2SA is preferably 600m. 2 / g or less, more preferably 300m 2 Below / g, and more preferably 250m 2 / g or less, especially preferably 200m 2 / g or less. When the N2SA is within the above range, it tends to achieve beneficial effects more appropriately.

[0117] In this paper, the N2SA of silica was determined according to ASTM D3037-81 by the BET method.

[0118] Silica can be commercially available from companies such as Degussa, Rhodia, Tosoh Silicon Chemicals, Solvay Japan, or Tokuyama Corporation.

[0119] Relative to 100 parts by weight of rubber component, the amount of silica is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, even more preferably 15 parts by weight or more, further preferably 150 parts by weight or less, more preferably 100 parts by weight or less, even more preferably 80 parts by weight or less, particularly preferably 60 parts by weight or less, and most preferably 40 parts by weight or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0120] In the rubber composition, based on 100% by mass of all fillers (reinforcing fillers), the amount of silica is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. There is no particular upper limit, but it is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less. When this amount is within the above range, beneficial effects can be more appropriately achieved.

[0121] The rubber composition containing silica preferably also contains a silane coupling agent.

[0122] Any silane coupling agent can be used, examples of which include: sulfide-based silane coupling agents, such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, etc. (4-Trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl 2-Triethoxysilyl ethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilyl ethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilyl propyl methacrylate monosulfide; mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents. Coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; epoxypropoxysilane coupling agents, such as γ-epoxypropoxypropyltriethoxysilane and γ-epoxypropoxypropyltrimethoxysilane; nitrosilane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorinated silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Examples of commercially available silane coupling agents include products from Degussa, Momentive, Shin-Etsu Silicone, Tokyo Chemical Industry Co., Ltd., AZmax, and Dow Corning Toray Industries, Ltd. These can be used alone or in combination of two or more. Among these, sulfide-based and mercapto-based silane coupling agents are preferred because they tend to achieve better beneficial effects. More preferably, disulfide-based silane coupling agents with disulfide bonds, such as bis(3-triethoxysilylpropyl) disulfide.

[0123] The amount of silane coupling agent relative to 100 parts by weight of silica is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and even more preferably 20 parts by weight or less, and more preferably 15 parts by weight or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0124] The above rubber composition may contain carbon black.

[0125] Non-limiting examples of carbon black include: N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These can be used alone or in combination of two or more.

[0126] The nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 80 m². 2 / g or more, preferably 100m 2 / g or more, preferably 150m 2 / g or less, more preferably 130m 2 / g or less. When N2SA is within the above range, it tends to achieve better beneficial effects.

[0127] In this paper, the N2SA of carbon black was determined according to JIS K6217-2:2001.

[0128] Carbon black can be a commercially available product from companies such as Asahi Carbon Co., Ltd., Cabot Japan KK, Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, NSCC Carbon Co., Ltd., or Columbia Carbon.

[0129] Relative to 100 parts by weight of rubber component, the amount of carbon black is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, even more preferably 20 parts by weight or more, particularly preferably 30 parts by weight or more, further preferably 150 parts by weight or less, more preferably 100 parts by weight or less, even more preferably 80 parts by weight or less, particularly preferably 60 parts by weight or less, and most preferably 50 parts by weight or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0130] The above rubber composition may contain oil.

[0131] Examples of oils include processing oils, vegetable oils, and mixtures thereof. Examples of processing oils include paraffinic processing oils, aromatic processing oils, and naphthenic processing 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 oil, and tung oil. These can be used alone or in combination of two or more. For optimal results, processing oils are preferred, and aromatic processing oils are more preferred.

[0132] Oil can be a commercially available product of companies such as Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Japan Energy Corporation, Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., or Fuji Kosan Co., Ltd.

[0133] Relative to 100 parts by weight of the rubber component, the amount of oil is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, even more preferably 20 parts by weight or more, and even more preferably 50 parts by weight or less, more preferably 35 parts by weight or less. When this amount is within the above range, beneficial effects are more likely to be achieved. The amount of oil includes the amount of oil (if present) in the rubber used (oil-extended rubber).

[0134] The above-mentioned rubber composition may contain a resin.

[0135] Any resin commonly used in the tire industry can be used, examples of which include: rosin-based resins, coumarone-indene resins, α-methylstyrene-based resins, terpene-based resins, p-tert-butylphenol acetylene resins, acrylic (ester)-based resins, C5 resins, and C9 resins. Examples of commercially available resins include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals, Inc., BASF Corporation, Arizona Chemical Company, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., and Toa Synthetic Co., Ltd. These can be used alone or in combination of two or more.

[0136] The amount of resin relative to 100 parts by weight of rubber is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and even more preferably 30 parts by weight or less, and more preferably 20 parts by weight or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0137] The above-mentioned rubber composition may contain wax.

[0138] Non-limiting examples of waxes include: petroleum-based waxes, such as paraffin and microcrystalline waxes; naturally occurring waxes, such as plant waxes and animal waxes; and synthetic waxes, such as polymers of ethylene, propylene, or other similar monomers. These can be used alone or in combination of two or more. Among these, petroleum-based waxes are preferred, and paraffin waxes are more preferred.

[0139] Waxes can be commercially available products from companies such as Ouchi Shinshin Chemical Industry Co., Ltd., Nippon Seiwa Co., Ltd., or Seiko Chemical Co., Ltd.

[0140] Relative to 100 parts by weight of the rubber component, the amount of wax is preferably 0.3 parts by weight or more, more preferably 0.5 parts by weight or more, and even more preferably 20 parts by weight or less, more preferably 10 parts by weight or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0141] The above-mentioned rubber composition may contain antioxidants.

[0142] Examples of antioxidants include: naphthylamine antioxidants, such as phenyl-α-naphthylamine; diphenylamine antioxidants, such as octyl diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine antioxidants, such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine; quinoline antioxidants, such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants, such as 2,6-di-tert-butyl-4-methylphenol and styrylated phenol; and bisphenol antioxidants, triphenol antioxidants, or polyphenol antioxidants, such as tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more. Among these, p-phenylenediamine-based antioxidants and / or quinoline-based antioxidants are preferred.

[0143] Antioxidants can be commercially available products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., or Flexsys.

[0144] Relative to 100 parts by weight of the rubber component, the amount of antioxidant is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 10 parts by weight or less, and more preferably 5 parts by weight or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0145] The rubber composition described above may contain stearic acid.

[0146] Stearic acid can be conventional stearic acid, examples of which include products from NOF CORPORATION, Kao Corporation, Fujifilm, Koh Geny Co., Ltd., and Chiba Fatty Acid Co., Ltd.

[0147] Relative to 100 parts by weight of the rubber component, the amount of stearic acid is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 10 parts by weight or less, and more preferably 5 parts by weight or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0148] The above rubber composition may contain zinc oxide.

[0149] Zinc oxide can be conventional zinc oxide, examples of which include products from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0150] The amount of zinc oxide relative to 100 parts by weight of rubber component is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 10 parts by weight or less, and more preferably 5 parts by weight or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0151] The above rubber composition may contain sulfur.

[0152] Examples of sulfur include those commonly used in the rubber industry, such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur. These can be used alone or in combination of two or more.

[0153] Sulfur can be a commercially available product of companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flex Industries, Nippon Inkryu Co., Ltd., or Hosoi Chemical Industry Co., Ltd.

[0154] Relative to 100 parts by mass of rubber component, the amount of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, further preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. When this amount is within the above range, the beneficial effects tend to be better achieved.

[0155] The above rubber composition may contain a vulcanization accelerator.

[0156] Examples of vulcanization accelerators include: thiazole-based vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators, such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxyethylidene-2-benzothiazole sulfenamide, N-oxyethylidene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine, and o-tolyldiguanidine. These can be used alone or in combination of two or more. For better results, sulfenamide-based and guanidine-based vulcanization accelerators are preferred. A combination of sulfenamide-based and guanidine-based vulcanization accelerators is more preferred.

[0157] The vulcanization accelerator can be a commercially available product from companies such as Kawaguchi Chemical Industry Co., Ltd. or Ouchi Shinsei Chemical Industry Co., Ltd.

[0158] The amount of vulcanization accelerator relative to 100 parts by weight of rubber component is preferably 1 part by weight or more, more preferably 2 parts by weight or more, and even more preferably 10 parts by weight or less, more preferably 7 parts by weight or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0159] In addition to the components mentioned above, the rubber composition may also contain additives commonly used in the tire industry, including, for example, organic peroxides; and fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. The amount of these additives is preferably 0.1 to 200 parts by weight relative to 100 parts by weight of the rubber component.

[0160] The above-mentioned rubber composition can be manufactured, for example, by mixing the above-mentioned components in a rubber mixing apparatus such as an open rolling mill or a Banbury mixer, and then vulcanizing the mixture.

[0161] The mixing conditions are as follows: In the basic mixing step, which involves mixing additives other than the vulcanizing agent and vulcanization accelerator, the mixing temperature is typically 100–180°C, preferably 120–170°C; in the final mixing step, which involves mixing the vulcanizing agent and vulcanization accelerator, the mixing temperature is typically below 120°C, preferably 80–110°C. The composition obtained by mixing the vulcanizing agent and vulcanization accelerator is then typically vulcanized, for example, by pressure vulcanization. The vulcanization temperature is typically 140–190°C, preferably 150–185°C. The vulcanization time is typically 5–15 minutes.

[0162] The above-described rubber composition can be used in tire components (i.e., as a rubber composition for tires), such as the tread (driving surface), sidewall, tread base, bottom tread, shoulder, clinch, bead gusset, cushion rubber, rubber for bonding carcass cords, insulation, bead wrapping and inner liner, and sidewall reinforcement layers of run-flat tires. The above-described rubber composition is particularly suitable for tire components (tread, sidewall, shoulder) that are in contact with water, and is especially suitable for the tread. When the tread consists of a driving surface and a tread base, the rubber composition can be applied to the driving surface.

[0163] Examples of tire components that may come into contact with water include components located on the outermost surface of a new tire or a worn tire (tread, sidewall, shoulder).

[0164] The tires of the present invention (e.g., pneumatic tires) can be prepared from the above-described rubber composition by conventional methods. Specifically, an uncured rubber composition containing various additives as needed can be extruded into the shape of tire parts (especially treads (tread running surfaces)), formed on a tire forming machine by conventional methods, and assembled with other tire parts to manufacture an uncured tire. The uncured tire can then be heated and pressurized in a vulcanizer to manufacture a tire.

[0165] The tire components (e.g., the tread) of the aforementioned tire may at least partially comprise the aforementioned rubber composition. All tire components may comprise the aforementioned rubber composition.

[0166] The above-mentioned tires are suitable for use as, for example, passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, or two-wheeled vehicle tires, or as racing tires, studless anti-skid winter tires (winter tires), all-season tires, run-flat tires, aircraft tires, or mining tires.

[0167] [Example]

[0168] The present invention will be specifically described with reference to the embodiments, but the present invention is not limited to these embodiments.

[0169] (Manufacturing Example 1)

[0170] Hexane, 1,3-butadiene, styrene, tetrahydrofuran, and ethylene glycol diethyl ether were charged into a nitrogen-purged autoclave reactor. Subsequently, solutions of bis(diethylamino)methylvinylsilane in cyclohexane and n-butyllithium in n-hexane were introduced, respectively, to initiate polymerization.

[0171] The copolymerization of 1,3-butadiene and styrene was carried out for 3 hours while the monomers were continuously fed into the reactor at a stirring speed of 130 rpm and an internal reactor temperature of 65°C. Then, the resulting polymer solution was stirred at 130 rpm, N-(3-dimethylaminopropyl)acrylamide was added, and the reaction was continued for 15 minutes. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. The solvent was then removed by steam stripping, and the product was dried on hot rollers adjusted to 110°C to obtain modified styrene-butadiene rubber (SBR).

[0172] (Manufacturing Example 2) Synthesis of Polymer 1 (Epoxide / Allyl Glycidyl Ether Copolymer)

[0173] 500 mL of diethyl ether was added to a nitrogen-purged glass flask. After cooling the internal temperature to below 0 °C, 10 mL of a 0.55 mol / L triisobutylaluminum solution in hexane was added, followed by dropwise addition of a 0.55 mol / L ethanol / diethyl ether solution, ensuring the internal temperature did not exceed 10 °C. Subsequently, a solution prepared by mixing a total of 200 g of ethylene oxide and allyl glycidyl ether in a 9:1 molar ratio was added dropwise, ensuring the internal temperature did not exceed 10 °C, and the mixture was stirred for 8 hours. Then, the solvent was evaporated under reduced pressure at an external temperature of 50 °C and an internal pressure below 1.0 kPa. The residue was then suspended in water and filtered. The filter residue was washed with THF and then dried under reduced pressure at 50°C and below 1 kPa until it reached constant weight, thereby obtaining polymer 1 in 80% yield (infrared absorption spectra show ether peaks from formula (A) and carbon-carbon peaks from formula (B), respectively; weight average molecular weight (Mw) of 780,000; the amount of groups (structural units) shown in formula (B) is 8 mol% based on 100 mol% of polymer).

[0174] (Manufacturing Example 3) Synthesis of Polymer 2 (Amine / Allyl Glycidyl Ether Copolymer)

[0175] The operation was carried out according to Manufacturing Example 2, but triglycidylamine was used instead of ethylene oxide, and a polymer of triglycidylamine and allyl glycidyl ether was obtained in 80% yield as Polymer 2 (the same analysis as Manufacturing Example 2 showed amine absorption and carbon-carbon double bond peaks; weight average molecular weight was 980,000; the amount of the group (structural unit) shown in Formula (B) was 8 mol% based on 100 mol% of the polymer).

[0176] (Manufacturing Example 4) Synthesis of Polymer 3 (Silyl / Allyl Glycidyl Ether Copolymer)

[0177] The operation was carried out according to Manufacturing Example 2, but triethoxysilyl glycidyl ether was used instead of ethylene oxide to obtain a polymer of triethoxysilyl glycidyl ether and allyl glycidyl ether in 80% yield as Polymer 3 (the same analysis as Manufacturing Example 2 showed silanol absorption and carbon-carbon double bond peaks; weight average molecular weight was 640,000; the amount of the group (structural unit) shown in Formula (B) was 8 mol% based on 100 mol% of the polymer).

[0178] (Manufacturing Example 5) Synthesis of Polymer 4 (Ethylene oxide / allyl glycidyl ether / halogenated monomer copolymer)

[0179] The operation was carried out according to Manufacturing Example 2, but ethylene oxide, allyl glycidyl ether and epichlorohydrin were used in a molar ratio of 8:1:1 to obtain a polymer of ethylene oxide, allyl glycidyl ether and epichlorohydrin as polymer 4 in a yield of 78% (the same analysis as Manufacturing Example 2 showed ether group peaks from formula (A), carbon-carbon double bond peaks from formula (B) and carbon-chlorine bond peaks from epichlorohydrin, respectively; the weight average molecular weight was 620,000; the amount of groups (structural units) and chlorine-carbon bond structural units shown in formula (B) were 8 mol% and 11 mol% respectively, based on 100 mol% of the polymer).

[0180] (Manufacturing Example 6) Synthesis of Polymer 5 (Ethylene Oxide / Allyl Glycidyl Ether / Phosphorus Monomer Copolymer)

[0181] The operation was carried out according to Manufacturing Example 2, but ethylene oxide, allyl glycidyl ether, and dimethyl 2-epoxyalkyl methyl phosphate were used in a molar ratio of 8:1:1 to obtain a polymer of ethylene oxide, allyl glycidyl ether, and dimethyl 2-epoxyalkyl methyl phosphate in a yield of 78% as Polymer 5 (analysis as in Manufacturing Example 2 showed an ether group peak from Formula (A), a carbon-carbon double bond peak from Formula (B), and a phosphorus-oxygen bond peak from dimethyl 2-epoxyalkyl methyl phosphate; the weight average molecular weight was 670,000; and the amount of the group (structural unit) and the amount of the phosphorus-oxygen bond structural unit shown in Formula (B) were 8 mol% and 11 mol%, respectively, based on 100 mol% of the polymer).

[0182] (Manufacturing Example 7) Synthesis of Polymer 6 (Ethylene oxide / allyl glycidyl ether / sulfur monomer copolymer)

[0183] The operation was carried out according to Manufacturing Example 2, but ethylene oxide, allyl glycidyl ether and 2-[(methylthio)methyl]ethylene oxide were used in a molar ratio of 8:1:1, and a polymer of ethylene oxide, allyl glycidyl ether and 2-[(methylthio)methyl]ethylene oxide was obtained in a yield of 78% as Polymer 6 (the same analysis as Manufacturing Example 2 showed an ether group peak from Formula (A), a carbon-carbon double bond peak from Formula (B) and a sulfur-carbon bond peak from 2-[(methylthio)methyl]ethylene oxide; the weight average molecular weight was 650,000; the amount of the group (structural unit) and the amount of the sulfur-carbon bond structural unit shown in Formula (B) were 8 mol% and 11 mol% respectively, based on 100 mol% of the polymer).

[0184] These polymers 1 to 6 were evaluated as follows.

[0185] Determination of Water-Insoluble Matter

[0186] Weigh 1 g of each polymer in a glass flask, pour 10 mL of water into the flask, and then stir for 10 minutes at an internal temperature of 66 °C. Then, continue stirring until the internal temperature reaches below 25 °C. Filter the obtained mixture through a filter paper with a mesh size of 5C and made of cellulose. After drying the residue remaining on the filter paper for 8 hours at a temperature of 80 °C and an internal pressure of below 0.1 kPa, measure the weight of the dried residue. Use the following formula to determine the amount of water-insoluble matter.

[0187] Amount of water-insoluble matter (mass %) = Weight of dried residue (g) / Initial weight of polymer (g) × 100

[0188] <Determination of THF-insoluble matter>

[0189] Weigh 1 g of each polymer in a glass flask, pour 10 mL of tetrahydrofuran into the flask, and then stir for 10 minutes at an internal temperature of 66 °C. Then, continue stirring until the internal temperature reaches below 25 °C. Filter the obtained mixture through a filter paper with a mesh size of 5C and made of cellulose. After drying the residue remaining on the filter paper for 8 hours at a temperature of 80 °C and an internal pressure of below 0.1 kPa, measure the weight of the dried residue. Use the following equation to determine the amount of THF-insoluble matter.

[0190] Amount of THF-insoluble matter (mass %) = Weight of dried residue (g) / Initial weight of polymer (g) × 100

[0191] The chemicals used in the examples and comparative examples are listed below.

[0192] SBR: SBR synthesized as described above (modified S-SBR, styrene content: 25 mass %, vinyl content: 59 mol %, not filled with oil)

[0193] BR: BR150B purchased from Ube Industries, Ltd. (cis content: 97 mass %)

[0194] NR: TSR20

[0195] Polymer 1: Polymer 1 synthesized as described above (water-insoluble matter: 96 mass %, THF-insoluble matter: 96 mass %)

[0196] Polymer 2: Polymer 2 synthesized as described above (water-insoluble matter: 82 mass %, THF-insoluble matter: 96 mass %)

[0197] Polymer 3: Polymer 3 synthesized as described above (water-insoluble matter: 92 mass %, THF-insoluble matter: 92 mass %)

[0198] Polymer 4: Polymer 4 synthesized as described above (water insoluble: 97% by mass, THF insoluble: 97% by mass)

[0199] Polymer 5: Polymer 5 synthesized as described above (water insoluble: 95% by mass, THF insoluble: 95% by mass)

[0200] Polymer 6: Polymer 6 synthesized as described above (water insoluble: 94% by mass, THF insoluble: 96% by mass)

[0201] Silica: Purchased from Rhodia's ZEOSIL 1165MP (N2SA: 160m) 2 / g)

[0202] Carbon black: Seast 9H (DBP oil absorption: 115mL / 100g, N2SA: 110m) purchased from Tokai Carbon Co., Ltd. 2 / g)

[0203] Silane coupling agent: Si75 (bis(3-triethoxysilylpropyl) disulfide) purchased from Evonik Degussa.

[0204] Oil: Process X-140 (aromatic processing oil) purchased from Japan Energy Corporation.

[0205] Wax: Ozoace 0355 purchased from Japan Fine Wax Co., Ltd.

[0206] Antioxidant: Santoflex 13 (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 6 PPD) purchased from Flex.

[0207] Stearic acid: Stearic acid "TSUBAKI" purchased from Nippon Yu Co., Ltd.

[0208] Zinc oxide: Zinc oxide #2 purchased from Mitsui Metals & Minerals Co., Ltd.

[0209] Sulfur: Powdered sulfur purchased from Tsurumi Chemical Industry Co., Ltd.

[0210] Vulcanization accelerator 1: NOCCELER NS (N-tert-butyl-2-benzothiazolyl sulfenamide) purchased from Ouchi Shinshin Chemical Industry Co., Ltd.

[0211] Vulcanization accelerator 2: NOCCELER D (1,3-diphenylguanidine) purchased from Ouchi Shinshin Chemical Co., Ltd.

[0212] (Examples and Comparative Examples)

[0213] According to the formulations shown in Table 1, the chemicals, excluding sulfur and vulcanization accelerator, were mixed for 4 minutes at 160°C using a 1.7L Banbury internal mixer (Kobe Steel Corporation) to provide a compound. Then, the compound was mixed with sulfur and vulcanization accelerator for 4 minutes at 80°C in an open rolling mill to provide an unvulcanized rubber composition.

[0214] An uncured rubber composition is vulcanized under pressure at 170°C for 12 minutes to provide a vulcanized rubber composition.

[0215] The vulcanized rubber composition prepared as described above was evaluated as follows. Table 1 shows the results.

[0216] (Dynamic modulus E*)

[0217] The E* of the test vulcanized rubber sheet was measured using a spectrometer (Uejima Manufacturing Co., Ltd.) at a strain of 2%, a frequency of 10 Hz, and a temperature of 0°C.

[0218] (Dynamic modulus E* when wetted)

[0219] A vulcanized rubber sheet (with dimensions of 30.0 mm long × 30.0 mm wide × 4 mm thick) was immersed in water at 25°C for 10 hours, and then shaped into a 1 mm thick sheet. This sheet was used as a test vulcanized rubber sheet.

[0220] (Dynamic modulus E* during drying)

[0221] The water-wetted vulcanized rubber composition was dried under reduced pressure at 80°C and below 1 kPa until it reached constant weight, thereby obtaining a dried vulcanized rubber composition. After the temperature of the dried vulcanized rubber composition was returned to 25°C, the dynamic modulus E* of the dried vulcanized rubber composition was determined as described above, and this dynamic modulus was recorded as the dynamic modulus at drying time.

[0222] (Dynamic modulus E* when re-wetted with water)

[0223] Further, the dried vulcanized rubber composition was immersed in water at 25°C for 10 hours to provide a vulcanized rubber composition that was rewetted with water. The dynamic modulus E* of the vulcanized rubber composition that was rewetted with water was determined as described above, and this dynamic modulus was recorded as the dynamic modulus E* when rewetting with water.

[0224] (tanδ during drying)

[0225] The tanδ of dried vulcanized rubber compositions at 70°C was determined using a viscoelastic spectrometer (VES) (Iwamoto Seisakusho Co., Ltd.). The measurement conditions were as follows: measurement temperature 70°C, initial strain 10%, dynamic strain 2%, and frequency 10 Hz.

[0226] (Fuel Economy Index)

[0227] Each uncured rubber composition was molded into a tread shape and then assembled with other tire components. Subsequently, it was vulcanized under pressure at 150°C for 15 minutes to produce test tires (size: 195 / 65R15). The test tires were run in a rolling resistance testing machine under conditions including a 15×6JJ rim, an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h to measure rolling resistance. Rolling resistance was expressed as an index (fuel economy index), with Comparative Example 1 set to 100. A higher index indicates better fuel economy.

[0228] (Wet Grip Performance Index)

[0229] Each uncured rubber composition was shaped into a tread form and then assembled with other tire components. Subsequently, it was vulcanized under pressure at 150°C for 15 minutes to produce a kart tire (tire size: 11 × 1.10-5). Each set of kart tires was mounted on a kart. Test drivers drove the kart eight laps around a 2km test track (the track surface was pre-sprayed with water). The drivers then evaluated the grip performance on a scale of 1 to 200 (optimal), with Comparative Example 1's grip performance set at 100.

[0230] (Dry Grip Performance Index)

[0231] Each uncured rubber composition was shaped into a tread pattern and then assembled with other tire components. Subsequently, it was vulcanized under pressure at 150°C for 15 minutes to produce tires for mini-racing cars (tire size: 11 × 1.10-5). Each set of mini-racing tires was mounted on a mini-racing car. Test drivers drove the mini-racing car eight laps around a 2km test track on dry roads. The drivers then evaluated the grip performance on a scale of 1 to 200 (optimal), with the grip performance of Comparative Example 1 set at 100.

[0232] [Table 1]

[0233]

[0234] Table 1 shows that the embodiment with a dynamic modulus E* that changes reversibly with water and satisfies the above relationship (1) exhibits improved overall performance in terms of wet grip and dry grip (as shown by the two indices: the sum of wet grip and dry grip).

Claims

1. A rubber composition, wherein, The rubber composition has a dynamic modulus E that changes reversibly with water. And it satisfies the following relation (1): Dynamic modulus E when wetted / Dynamic modulus E during drying ×100%≤90% (1) Dynamic modulus E when wetted and dynamic modulus E during drying It was measured using the following method: Dynamic modulus E when wetted : A vulcanized rubber composition was obtained by vulcanizing the rubber composition. The vulcanized rubber composition was then formed into a vulcanized rubber sheet with dimensions of 30.0 mm long × 30.0 mm wide × 4 mm thick. The vulcanized rubber sheet was immersed in water at 25°C for 10 hours. The vulcanized rubber sheet was then formed into a 1 mm thick sheet to provide a water-wetted vulcanized rubber sheet. Subsequently, the E0 of the water-wetted vulcanized rubber sheet was measured using a spectrometer at a strain of 2%, a frequency of 10 Hz, and a temperature of 0°C. And denoted as the dynamic modulus E when wetted by water. ; Dynamic modulus E during drying : Water-wetted vulcanized rubber sheets were dried under reduced pressure at 80°C and below 1 kPa until constant weight to obtain dried vulcanized rubber sheets. After the dried vulcanized rubber sheets were returned to 25°C, the E0 of the dried vulcanized rubber sheets was measured using a spectrometer at 2% strain, 10 Hz frequency, and 0°C temperature. And denoted as the dynamic modulus E during drying. .

2. The rubber composition according to claim 1, in, The relation (1) is as follows: Dynamic modulus E when wetted / Dynamic modulus E during drying ×100%≤85%.

3. The rubber composition according to claim 1, in, The relation (1) is as follows: Dynamic modulus E when wetted / Dynamic modulus E during drying ×100%≤80%.

4. The rubber composition according to claim 1, in, The relation (1) is as follows: Dynamic modulus E when wetted / Dynamic modulus E during drying ×100%≤75%.

5. The rubber composition according to any one of claims 1 to 4, in, The rubber composition comprises: Diene-based rubbers, and Polymers containing carbon-carbon double bonds and heteroatoms.

6. The rubber composition according to claim 5, in, The heteroatom is at least one atom selected from oxygen, nitrogen, silicon, sulfur, phosphorus and halogen atoms.

7. The rubber composition according to claim 5, in, The polymer contains at least 5% by mass of insoluble matter when suspended in 10 mL of water at a concentration of 1 g.

8. The rubber composition according to claim 5, in, When the polymer is suspended in 10 mL of tetrahydrofuran at a concentration of 1 g, it contains at least 5% by mass of insoluble matter.

9. The rubber composition according to claim 5, in, The rubber composition contains at least 5 parts by mass of polymer relative to 100 parts by mass of the rubber component in the rubber composition.

10. The rubber composition according to any one of claims 1 to 4, in, The rubber composition contains isoprene-based rubber.

11. The rubber composition according to any one of claims 1 to 4, in, The rubber composition contains polybutadiene rubber.

12. The rubber composition according to any one of claims 1 to 4, in, The rubber composition contains styrene-butadiene rubber, and the content of styrene-butadiene rubber is less than 95% by mass, based on the rubber component of the rubber composition as 100% by mass.

13. The rubber composition according to any one of claims 1 to 4, in, Rubber compositions are used in tire treads.

14. A tire, wherein, The tire has tire components that at least partially comprise the rubber composition of any one of claims 1 to 12.

15. The tire according to claim 14, in, The tire component is the tread.

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