Vulcanized rubber composition and tire

Abstract

To provide a vulcanized rubber composition that has improved general performances such as low fuel economy and wet grip, and a pneumatic tire.SOLUTION: A vulcanized rubber composition contains, in a rubber component 100 mass%, a styrene-butadiene rubber of 10-100 mass% and also contains, relative to the rubber component 100 pts.mass, a resin of 5-200 pts.mass. A transmission measurement is carried out by Fourier transform infrared spectroscopy, before and after acetone extraction, respectively, so that a peak around 1600 cm-1 shifts by 0.5 cm-1 or more.SELECTED DRAWING: None

Description

[Technology Field]

[0001] This invention relates to a vulcanized rubber composition and a tire. [Background technology]

[0002] From the perspective of fuel efficiency during vehicle operation, there is a demand to reduce tire rolling resistance. Furthermore, from the perspective of safety, there is a demand for improved wet grip performance (braking performance on wet surfaces). However, these performances are conflicting. In response to this, a method is known that can achieve both low rolling resistance and wet grip performance by incorporating silica (for example, Patent Document 1). However, silica has low affinity with rubber components, and silica particles have high cohesiveness, so although there is a method using a silane coupling agent, there are limitations to the dispersion effect of silica with rubber components. Therefore, there is still room for improvement in the technology that achieves both low rolling resistance and wet grip performance. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-99080 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to solve the aforementioned problems and provide a vulcanized rubber composition and a pneumatic tire that have improved overall performance in terms of fuel efficiency and wet grip performance. [Means for solving the problem]

[0005] In this invention, the rubber component contains 10 to 100% by mass of styrene-butadiene rubber, and contains 5 to 200 parts by mass of resin per 100 parts by mass of rubber component. When transmission measurements by Fourier transform infrared spectroscopy were performed before and after acetone extraction, the measured value was 1600 cm⁻¹. -1 The nearby peak is 0.5 cm. -1 The above relates to a vulcanized rubber composition that exhibits the above shift.

[0006] In the above measurement, the peak around 1600 cm -1 is preferably shifted by 0.6 cm -1 or more, more preferably shifted by 0.7 cm -1 or more, and even more preferably shifted by 0.8 cm -1 or more.

[0007] It is preferable that the above resin is at least one resin selected from the group consisting of C5 resin, C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, and rosin.

[0008] It is preferable that the above resin is a resin having an aromatic ring.

[0009] It is preferable that the above rubber composition contains silica.

[0010] The present invention also relates to a tire having a tread using the above rubber composition.

Effects of the Invention

[0011] According to the present invention, in 100% by mass of the rubber component, the content of styrene-butadiene rubber is 10 to 100% by mass, and 5 to 200 parts by mass of resin is contained per 100 parts by mass of the rubber component. When transmission measurements by Fourier transform infrared spectroscopy are respectively carried out before and after acetone extraction, the peak around 1600 cm -1 is shifted by 0.5 cm -1 or more. Therefore, the overall performance of low fuel consumption and wet grip performance can be improved.

Modes for Carrying Out the Invention

[0012] The vulcanized rubber composition of the present invention contains 10 to 100% by mass of styrene-butadiene rubber in 100% by mass of the rubber component, contains 5 to 200 parts by mass of resin with respect to 100 parts by mass of the rubber component, and when transmission measurements by Fourier transform infrared spectroscopy are respectively carried out before and after acetone extraction, the peak near 1600 cm -1 shifts by 0.5 cm -1 or more. Thereby, the overall performance of low fuel consumption and wet grip performance can be improved.

[0013] The above vulcanized rubber composition has the above-described effects, but the reason for obtaining such effects is not necessarily clear, but it is presumed as follows. The above vulcanized rubber composition contains styrene-butadiene rubber (SBR) and resin, and when transmission measurements by Fourier transform infrared spectroscopy are respectively carried out before and after acetone extraction, the peak near 1600 cm -1 shifts by 0.5 cm -1 or more. The peak near the above 1600 cm -1 is a peak derived from the aromatic ring of styrene of SBR. By performing acetone extraction, the resin dissolves, and therefore, by performing transmission measurements by Fourier transform infrared spectroscopy before and after acetone extraction, the behavior of the resin in the vulcanized rubber composition can be analyzed. And, the fact that the peak near 1600 cm -1 shifts (shifts to the lower wavenumber side) before and after acetone extraction indicates that the resin and the aromatic ring of styrene of SBR interact, and the electron density in the aromatic ring plane (styrene) of SBR is decreased. The interactions between the resin and SBR include π-π interaction and CH-π interaction, and the resin interacts with different SBRs respectively. That is, when transmission measurements by Fourier transform infrared spectroscopy are respectively carried out before and after acetone extraction, the peak near 1600 cm -1 shifts by 0.5 cm -1 or more, which means that the resin penetrates into the polymer (SBR) molecules (disperses at the nano level), exhibits an interaction, and suppresses the molecular mobility of the polymer (SBR), and thereby, the wet grip performance can be improved. On the other hand, before and after acetone extraction, 0.5 cm -1 In the vulcanized rubber composition that undergoes the above shift, when the temperature rises, the molecular motion of the polymer becomes more active and the dynamic strain increases, causing some of the interactions formed by the resin to break down. As a result, the resin functions as a plasticizer while maintaining its interaction with SBR, and the resin softens the vulcanized rubber composition, resulting in good fuel efficiency. As described above, the vulcanized rubber composition contains SBR and resin, and when transmission measurements were performed using Fourier transform infrared spectroscopy before and after acetone extraction, the reading was 1600 cm⁻¹. -1 The nearby peak is 0.5 cm. -1 As a result of this shift, the SBR and resin interact effectively, improving wet grip performance while maintaining or improving good fuel efficiency, thus improving overall performance in terms of fuel efficiency and wet grip performance. Furthermore, the greater the peak shift, the better the wet grip performance.

[0014] In this specification, acetone extraction and transmission measurement by Fourier transform infrared spectroscopy (FT-IR) are performed by the method described in the examples. Furthermore, in this specification, a peak shift means that the position of the peak top shifts (changes).

[0015] The above vulcanized rubber composition showed a transmission rate of 1600 cm² when measured by Fourier transform infrared spectroscopy before and after acetone extraction. -1 The nearby peak is 0.5 cm. -1 Shift by more than 0.6 cm, preferably 0.6 cm. -1 Shifted by more than 0.7 cm, more preferably 0.7 cm. -1 Shift by more than 0.8 cm, and more preferably by 0.8 cm. -1 Shift by more than 0.9 cm, and particularly preferably 0.9 cm. -1 Shift by more than 1.0 cm, most preferably 1.0 cm. -1 Shifted by more than 1.1 cm, more preferably 1.1 cm -1Shift by more than 1.2 cm, more preferably 1.2 cm -1 Shifted by more than 1.3 cm, more preferably by 1.3 cm -1 Shifted by more than 1.4 cm, more preferably by 1.4 cm -1 Shift by more than 1.5 cm, more preferably 1.5 cm -1 Shift by more than 1.6 cm, more preferably 1.6 cm -1 Shifted by more than 1.7 cm, more preferably 1.7 cm -1 Shifted by more than 1.8 cm, more preferably 1.8 cm -1 The shift is greater than or equal to the maximum shift. Since a larger peak shift results in better wet grip performance, there is no particular upper limit to the shift, but it is preferably 4.0 cm. -1 More preferably 3.8 cm -1 More preferably 3.0 cm -1 The following is particularly preferable: 2.5 cm -1 The following applies. Within the above range, the effect is more favorably obtained. The above shift width is measured by the method described in the embodiment.

[0016] The above-mentioned peak shift can be achieved by using SBR in combination with a resin that is highly compatible with SBR. This is because when SBR and a resin that is highly compatible with SBR are used together, SBR and the resin interact favorably. Examples of resins that are highly compatible with SBR include resins that have aromatic rings.

[0017] Other means of achieving the above peak shift include methods of incorporating a resin that induces π-π interactions or CH-π interactions between SBR and the resin, or a resin having electron-withdrawing groups.

[0018] The following describes the chemicals that can be used with the above-mentioned vulcanized rubber composition (also called rubber composition).

[0019] The above vulcanized rubber composition contains styrene-butadiene rubber (SBR). SBR is not particularly limited; for example, emulsion-polymerized SBR (E-SBR), solution-polymerized SBR (S-SBR), and other types commonly used in the tire industry can be used. These may be used individually or in combination of two or more types. Among these, S-SBR is preferred because it provides the desired overall performance.

[0020] The styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0021] The vinyl content of SBR is preferably 5% by mass or more, more preferably 15% 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 also preferably 70% by mass or less, more preferably 65% ​​by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0022] SBR can be either unmodified SBR or modified SBR. Modified SBRs can be any SBR having a functional group that interacts with a packing material such as silica. Examples include terminally modified SBRs (terminally modified SBRs having the functional group at the terminal) in which at least one end of the SBR is modified with a compound having the functional group (modifying agent), main-chain modified SBRs having the functional group in the main chain, main-chain terminally modified SBRs having the functional group in both the main chain and the terminal (for example, main-chain terminally modified SBRs having the functional group in the main chain and at least one end modified with the modifying agent), and terminally modified SBRs that are 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. These may be used individually or in combination of two or more types.

[0023] 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), alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6), and amide groups are preferred.

[0024] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used.

[0025] The SBR content in 100% by mass of the rubber component is 10% by mass or more, preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. It may be 100% by mass, but is preferably 90% by mass or less, and more preferably 80% by mass or less. When it is within the above range, a better effect tends to be obtained.

[0026] Other rubber components that can be used besides SBR include, for example, diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene-isoprene-butadiene rubber (SIBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). The rubber components may be used individually or in combination of two or more. Among these, diene rubbers are preferred, isoprene rubber and BR are more preferred, and BR is even more preferred. By adding BR, which has good compatibility with SBR, in addition to SBR, the effect can be more favorably obtained.

[0027] Here, the rubber component is preferably a rubber with a weight-average molecular weight (Mw) of 150,000 or more, and more preferably 350,000 or more. The upper limit of Mw is not particularly limited, but is preferably 4 million or less, and more preferably 3 million or less.

[0028] The content of diene rubber in 100% by mass of the rubber component 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 it is within the above range, the effect tends to be better obtained.

[0029] The BR is not particularly limited and can be any that is common in the tire industry. For example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare-earth catalyst (rare-earth BR) can be used. These may be used individually or in combination of two or more.

[0030] 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. The upper limit is not particularly limited and may be 100% by mass. When it is within the above range, the effect tends to be more favorably obtained.

[0031] BR may be either unmodified BR or modified BR. Modified BR includes modified BR into which the aforementioned functional groups have been introduced. Preferred embodiments are the same as in the case of modified SBR.

[0032] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0033] The BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less. Within this range, a better effect tends to be obtained.

[0034] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, examples include SIR20, RSS#3, TSR20, etc., which are commonly used in the tire industry. For IR, there are no particular limitations; examples include IR2200, etc., which are commonly used in the tire industry. Examples of modified 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 isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more. Among these, NR is preferred.

[0035] The isoprene-based rubber content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less. Within this range, better effects tend to be obtained.

[0036] In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be determined by converting the measured values ​​obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene equivalents. Furthermore, the cis content (amount of cis-1,4-bonded butadiene units) and vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy, and the styrene content is 1 It can be measured by 1H-NMR.

[0037] The above rubber composition contains resin. This allows for a favorable effect to be obtained.

[0038] The softening point of the above resin is preferably 40°C or higher, more preferably 60°C or higher, and even more preferably 75°C or higher. While there is no particular upper limit to the softening point, it is preferably 180°C or lower, more preferably 160°C or lower, even more preferably 140°C or lower, and particularly preferably 120°C or lower. Within this range, the effects tend to be more favorably obtained. The softening point of the resin is determined by measuring the softening point specified in JIS K 6220-1:2001 using a ring-type softening point measuring device, and the temperature at which the sphere descends is the measured temperature.

[0039] The resins used are not particularly limited as long as they are commonly used in the tire industry, and include C5 resin, C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin (DCPD), styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, rosin, pt-butylphenolacetylene resin, acrylic resins, etc. These may be used individually or in combination of two or more. In this specification, "resin" refers to a polymer that is in a solid state at room temperature (25°C). Here, for example, α-methylstyrene resin is a resin that contains α-methylstyrene as the main monomer component constituting the resin's backbone (main chain), and may also contain other monomer components. The same applies to other resins.

[0040] In particular, at least one resin selected from the group consisting of C5 resin, C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, and rosin is preferred, and at least one resin selected from the group consisting of C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, and rosin is more preferred.

[0041] Furthermore, as mentioned above, resins having aromatic rings, which are highly compatible with SBR, are preferred. Examples of resins having aromatic rings include C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, rosin, and pt-butylphenolacetylene resin. These may be used individually or in combination of two or more. Among these, C9 resin, terpene phenol resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, and 4-tert-butylstyrene resin are preferred, α-methylstyrene resin, terpene phenol resin, styrene resin, and 4-tert-butylstyrene resin are more preferred, and α-methylstyrene resin is even more preferred. Furthermore, it is preferable to use multiple resins having aromatic rings in combination, specifically, a combination of α-methylstyrene resin, terpene phenol resin, styrene resin, and 4-tert-butylstyrene resin is preferred.

[0042] Examples of resins that can be used include those from 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., JX Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., Toagosei Co., Ltd., and Kraton Corporation.

[0043] The resin content is 5 parts by mass or more per 100 parts by mass of rubber component, preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, particularly preferably 35 parts by mass or more, most preferably 40 parts by mass or more, and also 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0044] The above rubber composition preferably contains carbon black. The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. These may be used individually or in combination of two or more types.

[0045] The nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 80 m². 2 / g or more, comfortably 100m 2 It is 1 / g or more, and preferably 200m 2 Less than / g, more preferably 150m 2 / g or less, more preferably 125m 2 It is less than or equal to / g. Within the above range, there is a tendency for better results to be obtained. In this specification, the N2SA value of carbon black is the value measured in accordance with JIS K6217-2:2001.

[0046] For carbon black, 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 can be used.

[0047] The carbon black content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, per 100 parts by mass of rubber component, and also preferably 80 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 10 parts by mass or less. Within the above range, a better effect tends to be obtained.

[0048] The above rubber composition preferably contains silica. Examples of silica include dry-process silica (anhydrous silicic acid) and wet-process silica (hydrated silicic acid), but wet-process silica is preferred because it has a higher silanol group content. These can be used individually or in combination of two or more types.

[0049] The specific surface area (N2SA) of silica for nitrogen adsorption is 40 m². 2 / g or more, preferably 70m 2 / g or more, more preferably 80m 2 / g or more, more preferably 140m 2 / g or more, particularly preferably 160m 2 It is 1 / g or more. Furthermore, the above N2SA is preferably 600m 2 Less than / g, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less, particularly preferably 200m 2 It is less than or equal to / g. Within the above range, the effect tends to be more favorably obtained. Note that the N2SA value of silica is measured by the BET method in accordance with ASTM D3037-81.

[0050] For example, silica products from companies such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation can be used.

[0051] The silica content 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 40 parts by mass or more, and most preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. It is also preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. When the silica content is within the above range, the effect tends to be better.

[0052] In the above rubber composition, the silica content in 100% by mass of the filler (reinforcing filler) is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 85% by mass or more, and may also be 100% by mass. When the silica content is within the above range, the effect tends to be more favorably obtained.

[0053] If the above rubber composition contains silica, it is preferable that it further contains 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, and 3-trimethoxysilylpropyl-N Examples include sulfide compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. These may be used individually or in combination of two or more. Among these, sulfide-based silane coupling agents are preferred because they tend to provide better results, and disulfide-based silane coupling agents having a disulfide bond, such as bis(3-triethoxysilylpropyl) disulfide, are more preferred.

[0054] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of silica. Within this range, a better effect tends to be obtained.

[0055] The above rubber composition may contain a softening agent. The softening agent is not particularly limited, but examples include oils and liquid diene polymers. These may be used individually or in combination of two or more.

[0056] 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. These may be used individually or in combination of two or more. Among these, process oils are preferred, and paraffinic process oils are more preferred, because they provide good results.

[0057] As for the oil, products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., and Fuji Kosan Co., Ltd. can be used.

[0058] Liquid diene polymers are diene polymers that are in a liquid state at room temperature (25°C). The weight-average molecular weight (Mw) of the liquid diene polymer is preferably 3.0 × 10⁶. 3 More preferably 4.0 × 10 3 The above, preferably 1.0 × 10 5More preferably 1.5 × 10 4 The following applies. Within the above range, the effect is more favorably obtained.

[0059] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR). These may be used individually or in combination of two or more. Among these, liquid SBR is preferred because it provides a more favorable effect.

[0060] The styrene content of liquid SBR is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, preferably 55% by mass or less, and more preferably 50% by mass or less. Within this range, the desired effect is more favorably obtained.

[0061] As liquid diene polymers, for example, products from companies such as Sartomer and Kuraray Co., Ltd. can be used.

[0062] The amount of softening agent is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and 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 rubber component. Within this range, a better effect tends to be obtained. In this specification, the amount of softening agent also includes the amount of oil contained in the rubber (oil-spread rubber).

[0063] The total content of resin and softener is preferably the same as the amount when the resin described above is used alone.

[0064] The above rubber composition preferably contains sulfur as a crosslinking agent (vulcanizing agent). Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. These may be used individually or in combination of two or more types.

[0065] For sulfur, products from companies such as Tsurumi Chemical Industries, Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industries, Ltd. can be used.

[0066] The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of rubber component. It is also preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0067] The above rubber composition preferably contains a vulcanization accelerator. 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, with sulfenamide-based vulcanization accelerators being more preferred.

[0068] Products from companies such as Kawaguchi Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Rhein Chemie can be used as vulcanization accelerators.

[0069] The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0070] The above rubber composition may also contain wax. The wax is not particularly limited and includes petroleum-based waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant-based waxes and animal-based waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used individually or in combination of two or more. Among these, petroleum-based waxes are preferred, and paraffin waxes are more preferred.

[0071] Examples of waxes that can be used include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0072] The wax content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of rubber component. Within this range, a better effect tends to be obtained.

[0073] The above rubber composition may also contain an anti-aging agent. Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents 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 2,2,4-trimethyl-1,2-dihydroquinoline polymers and other quinoline-based antioxidants; 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. These may be used individually or in combination of two or more types. Among these, p-phenylenediamine-based antioxidants are preferred.

[0074] Products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. can be used as anti-aging agents.

[0075] The amount of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0076] The above rubber composition may contain stearic acid. Conventional known stearic acid can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd., etc.

[0077] The stearic acid content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0078] The above rubber composition may contain zinc oxide. Conventional 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.

[0079] The zinc oxide content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0080] In addition to the components mentioned above, the above rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides; fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0081] The above rubber composition can be manufactured, for example, by kneading each of the components using a rubber kneading device such as an open roll or Banbury mixer, and then vulcanizing them.

[0082] Regarding the mixing conditions, in the base mixing step where additives other than the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish mixing step where the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 120°C or lower, preferably 80 to 110°C. Furthermore, the composition mixed with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0083] The above rubber composition can be used (as a tire rubber composition) in tire components such as the tread (cap tread), sidewall, base tread, under tread, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, and side reinforcement layer of run-flat tires. It is particularly suitable for use in the tread.

[0084] The tire (pneumatic tire, etc.) of the present invention is manufactured by conventional methods using the above-mentioned rubber composition. Specifically, the rubber composition, which may contain various additives as needed, is extruded in the unvulcanized stage to match the shape of each component of the tire (especially the tread (cap tread)), molded in conventional methods on a tire molding machine, bonded together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizing machine to manufacture the tire.

[0085] The above-mentioned tires are suitably used as passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, racing tires, studless tires (winter tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc. [Examples]

[0086] The present invention will be specifically described based on the examples provided, but the present invention is not limited to these examples.

[0087] The various chemicals used in the examples and comparative examples are described below. SBR: Nipol NS116 (S-SBR, vinyl content: 60% by mass, styrene content: 20% by mass) manufactured by Nippon Zeon Co., Ltd. BR: BR150B manufactured by Ube Industries, Ltd. (Cystic content: 97% by mass) NR:TSR20 (Natural Rubber) Carbon black: Mitsubishi Chemical Corporation's Seast I (N220, N2SA: 114m 2 / g) Silica: Uratosil VN3 (N2SA: 175m) manufactured by Evonik De Gussa. 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik DeGussa. Wax: OzoAce wax manufactured by Nippon Seiro Co., Ltd. Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Oil: PS-32 (paraffin-based process oil) manufactured by Idemitsu Kosan Co., Ltd. Resin (1): Sylvatraxx 4401 (α-methylstyrene resin, softening point 85°C) manufactured by Kraton Corporation. Resin (2): Quintone A100 (C5 resin, softening point 100°C) manufactured by Nippon Zeon Co., Ltd. Resin (3): SX100 (styrene resin, softening point 100°C) manufactured by Yasuhara Chemical Co., Ltd. Resin (4): T100 (terpene phenol resin, softening point 100°C) manufactured by Yasuhara Chemical Co., Ltd. Resin (5): Resin synthesized in the following manufacturing example (4-tert-butylstyrene resin, softening point 130°C) Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. (containing 5% oil) Vulcanization accelerator: Noxellar NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0088] (Manufacturing example) [Preparation of resin (5)] A stirrer, thermometer, and reflux condenser were attached to a 1L four-necked flask. 150.0g of 4-tert-butylstyrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 375ml of toluene (manufactured by Kanto Chemical Co., Ltd.) were added as a reaction mixture and thoroughly stirred. The uniformly dispersed reaction mixture was then cooled to 2°C under ice cooling. Meanwhile, 1.5g of boron trifluoride phenol complex and 3.0g of toluene were placed in a dropping funnel as a catalyst, and this dropping funnel was attached to the four-necked flask. Next, while maintaining the temperature at 3-5°C, the catalyst was added dropwise over 15 minutes to initiate the polymerization reaction. After the addition of the catalyst was complete, the mixture was stirred for another 30 minutes while maintaining the temperature at 3-5°C. After the polymerization reaction was complete, the reaction solution was washed with a 0.5N aqueous sodium hydroxide solution, followed by a rinse with water, and then dried over anhydrous sodium sulfate. This reaction solution was added dropwise over 30 minutes to 1200g of pre-prepared ethanol to obtain a powder precipitate. This powder was filtered, washed again with 300g of ethanol, and then dried under reduced pressure to obtain 58g of 4-tert-butylstyrene resin. The obtained resin had a softening point of 130°C.

[0089] (Examples and Comparative Examples) According to the formulation shown in Table 1, all chemicals except sulfur and vulcanization accelerator were mixed for 4 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture. Next, sulfur and vulcanization accelerator were added to the mixture and mixed for 4 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was press-vulcanized at 170°C for 12 minutes using a 0.5 mm thick mold to obtain a vulcanized rubber composition.

[0090] Furthermore, the obtained unvulcanized rubber composition was extruded into the shape of a cap tread, bonded together with other tire components on a tire molding machine to form an unvulcanized tire, and then press-vulcanized for 12 minutes under conditions of 170°C to obtain a test tire (tire size: 195 / 65R15).

[0091] The following evaluations were performed using the obtained vulcanized rubber composition (before acetone extraction) and test tires. The results are shown in Table 1.

[0092] <Rolling resistance> Using a rolling resistance tester, the rolling resistance of a test tire was measured when it was driven on a rim (15×6JJ), with an internal pressure of 230kPa, a load of 3.43kN, and a speed of 80km / h. The results were expressed as an index, with Comparative Example 1 set to 100. A higher index indicates better performance (lower fuel consumption). An index of 95 or higher was considered good.

[0093] <Wet Grip Performance Test> The above test tires were mounted on all wheels of a vehicle (domestic FF 2000cc), and the braking distance from an initial speed of 100 km / h was measured on a wet road surface. The results were expressed as an index, with Comparative Example 1 set to 100, using the following formula. A higher index indicates superior wet grip performance. (Wet grip performance index) = (Braking distance of Comparative Example 1) / (Braking distance of each example) × 100

[0094] <Transmission measurement using Fourier transform infrared spectroscopy> A vulcanized rubber composition (a rectangular parallelepiped measuring 0.5 mm × 10 mm × 50 mm before acetone extraction) was immersed in 100 ml of acetone at 25°C for 24 hours to obtain the vulcanized rubber composition after acetone extraction. Next, the vulcanized rubber composition (before acetone extraction) and the vulcanized rubber composition after acetone extraction were cut to a thickness of 10 μm using a Leica CM3050S cryostat. Transmission measurements by Fourier transform infrared spectroscopy were performed on each of these samples under the following conditions, and the 1600 cm⁻¹ measurement results for both samples were obtained. -1 By comparing the positions of the peaks in the vicinity, we can determine the position at 1600 cm before and after acetone extraction. -1 The shift range (change range) of nearby peaks was calculated. (Conditions for performing transmission measurements using Fourier transform infrared spectroscopy) Using PerkinElmer's Spectrum One. Mode: Transmission measurement Total number of times: 16 Temperature: 25℃

[0095] [Table 1]

[0096] Table 1 shows that the styrene-butadiene rubber content is 10 to 100% by mass of 100% by mass of the rubber component, and the resin is contained in 5 to 200 parts by mass per 100 parts by mass of the rubber component. When transmission measurements were performed by Fourier transform infrared spectroscopy before and after acetone extraction, the reading was 1600 cm⁻¹. -1 The nearby peak is 0.5 cm. -1 The above-mentioned shifted configuration was found to improve the overall performance of fuel efficiency and wet grip performance (the sum of both fuel efficiency and wet grip performance indices).

Claims

1. The content of styrene-butadiene rubber is 10 to 100% by mass in 100% by mass of the rubber component, The rubber component contains 5 to 200 parts by mass of resin per 100 parts by mass of rubber component, Before and after acetone extraction, Fourier transform infrared spectroscopy was performed to measure the transmittance at 1600 cm -1 The peak near 0.5cm -1 Vulcanized rubber composition shifting above.

2. In the above measurement, 1600 cm -1 The peak near 0.6 cm -1 The vulcanized rubber composition according to claim 1, wherein the shift is at least 100%.

3. In the above measurement, 1600 cm -1 The peak near 0.7 cm -1 The vulcanized rubber composition according to claim 1, wherein the shift is at least 100%.

4. In the above measurement, 1600 cm -1 The peak near 0.8 cm -1 The vulcanized rubber composition according to claim 1, wherein the shift is at least 100%.

5. 5. The vulcanized rubber composition according to claim 1, wherein the resin is at least one resin selected from the group consisting of C5 resin, C9 resin, limonene resin, α-pinene resin, β-pinene resin, terpene phenol resin, dicyclopentadiene resin, styrene resin, α-methylstyrene resin, coumarone resin, indene resin, phenol resin, 4-tert-butylstyrene resin, and rosin.

6. 5. The vulcanized rubber composition according to claim 1, wherein the resin has an aromatic ring.

7. 7. The vulcanized rubber composition according to claim 1, further comprising silica.

8. A tire having a tread made using the rubber composition according to any one of claims 1 to 7.