Rubber composition, tread rubber, and tire

Abstract

The present invention addresses the problem of providing a rubber composition capable of achieving both grip performance and fracture resistance. A means for solving the problem is a rubber composition containing: a rubber component containing a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more; an alkylphenol resin; and a hydrogenated resin.

Description

Rubber composition, tread rubber, and tire

[0001] The present invention relates to a rubber composition, a tread rubber, and a tire.

[0002] Conventionally, improved grip performance has been desired in tire treads, and techniques for increasing the amounts of resin and filler to improve grip performance have been known. For example, Patent Document 1 discloses a rubber composition for tires that contains 150 parts by mass or more of a white filler and 30 parts by mass or more of a resin per 100 parts by mass of a rubber component containing styrene-butadiene rubber.

[0003] Japanese Patent Application Laid-Open No. 2021-088676

[0004] However, while increasing the amount of resin and filler improves grip performance, there is a problem in that the fracture resistance deteriorates.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber composition that can achieve both grip performance and fracture resistance. Another object of the present invention is to provide a tread rubber that can achieve both grip performance and fracture resistance, and a tire that achieves both grip performance and fracture resistance.

[0006] The gist and configuration of the present invention to solve the above problems is as follows.

[0007] [1] A rubber composition comprising: a rubber component containing a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more; an alkylphenol resin; and a hydrogenated resin.

[0008] [2] The rubber composition according to [1], wherein the hydrogenated resin has a softening point higher than 110°C and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol.

[0009] [3] The rubber composition according to [1] or [2], wherein the hydrogenated resin is at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated dicyclopentadiene resins, and hydrogenated terpene resins.

[0010] [4] The rubber composition according to any one of [1] to [3], further comprising a filler, wherein the filler comprises carbon black.

[0011] [5] The rubber composition according to [4], wherein the filler further contains silica.

[0012] [6] The rubber composition according to [5], wherein the total content of the filler is 100 parts by mass or more per 100 parts by mass of the rubber component.

[0013] [7] The rubber composition according to any one of [1] to [6], wherein the content of the alkylphenol resin is 10 parts by mass or more per 100 parts by mass of the rubber component.

[0014] [8] The rubber composition according to any one of [1] to [7], wherein the content of the hydrogenated resin is 10 parts by mass or more per 100 parts by mass of the rubber component.

[0015] [9] A tread rubber comprising the rubber composition according to any one of [1] to [8].

[0016]

[10] A tire comprising the tread rubber according to [9].

[0017] According to the present invention, it is possible to provide a rubber composition that can achieve both grip performance and fracture resistance. Furthermore, according to the present invention, it is possible to provide a tread rubber that can achieve both grip performance and fracture resistance, and a tire that achieves both grip performance and fracture resistance.

[0018] The rubber composition, tread rubber, and tire of the present invention will be described in detail below by way of example based on embodiments thereof.

[0019] The compounds described herein may be derived in part or in whole from fossil sources, biological sources such as plant sources, recycled sources such as used tires, or a mixture of two or more of fossil, biological, and recycled sources.

[0020] <Rubber Composition> The rubber composition of this embodiment is characterized by including a rubber component containing styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more, an alkylphenol resin, and a hydrogenated resin. The inclusion of the alkylphenol resin and hydrogenated resin in the rubber composition improves grip performance. Meanwhile, the inclusion of these resins reduces fracture resistance, but the inclusion of a styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more in the rubber composition can suppress the reduction in fracture resistance. Therefore, the rubber composition of this embodiment can achieve both grip performance and fracture resistance.

[0021] (Rubber Component) The rubber composition of this embodiment contains a rubber component, which provides rubber elasticity to the rubber composition. The rubber composition of this embodiment also contains, as the rubber component, at least a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more. The rubber component may further contain other rubber components, such as a styrene-butadiene rubber other than the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more, natural rubber, or butadiene rubber.

[0022] [Styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more] In the present embodiment, the rubber component contains a styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more. By containing such a high-molecular-weight styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more, it is possible to suppress a decrease in the fracture resistance performance of the tire.

[0023] The styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more is not particularly limited, and those commonly used in the tire industry, such as emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR), can be used.

[0024] The proportion of the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more in the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of obtaining an effect of suppressing a decrease in fracture resistance. Furthermore, from the viewpoint of a balance with other physical properties, the proportion of the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more in the rubber component may be 90% by mass or less.

[0025] Styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more preferably has a styrene bond content of 10% by mass or more and 50% by mass or less. Here, the styrene bond content of the styrene-butadiene rubber refers to the content of styrene-derived monomer units in the styrene-butadiene rubber. The styrene bond content can be determined by an infrared method (Morello method).

[0026] From the viewpoint of suppressing a decrease in fracture resistance, the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more preferably has a weight average molecular weight of 800,000 or more, and more preferably 1,000,000 or more. Furthermore, the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more preferably has a weight average molecular weight (Mw) of 2,000,000 or less, and more preferably 1,500,000 or less. The weight average molecular weight of the styrene-butadiene rubber is a value measured by gel permeation chromatography (GPC).

[0027] Examples of commercially available styrene-butadiene rubbers having a weight average molecular weight (Mw) of 660,000 or more include Tufden 3835 (manufactured by Asahi Kasei Corporation), Tufden E581 (manufactured by Asahi Kasei Corporation), and T0150 (manufactured by ENEOS Materials Corporation).

[0028] The styrene-butadiene rubber having a weight-average molecular weight (Mw) of 660,000 or more may be either non-oil-extended or oil-extended, or may be a blend of non-oil-extended and oil-extended styrene-butadiene rubber. When the styrene-butadiene rubber is oil-extended, the extending oil is classified as a liquid softener component, which will be described later.

[0029] The styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more may be unmodified or modified, or may be a blend of unmodified and modified rubbers.

[0030] [Other Rubbers] The rubber composition of this embodiment may contain other rubbers other than styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more. Examples of such other rubbers include natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), styrene-isoprene rubber (SIR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), halogenated butyl rubber, and styrene-butadiene rubbers other than styrene-butadiene rubbers having a weight average molecular weight (Mw) of 660,000 or more. Among these, the other rubber is preferably a styrene-butadiene rubber other than styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more. These other rubbers may be used alone or in combination of two or more.

[0031] The content of the other rubber in the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, and may be 10% by mass or more, or 15% by mass or more.

[0032] Furthermore, when the other rubber contains a styrene-butadiene rubber other than a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more, the total content of the styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more and the styrene-butadiene rubber other than a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more (i.e., the total styrene-butadiene rubber content) is preferably 80% by mass or more, preferably 90% by mass or more, and may be 100% by mass in the rubber component.

[0033] The other rubber may be unmodified or modified, or may be a blend of unmodified and modified rubbers. The other rubber may be non-oil-extended or oil-extended, or may be a blend of non-oil-extended and oil-extended rubbers. If the other rubber is oil-extended, the extending oil is classified as a liquid softener component, which will be described later.

[0034] (Alkylphenol-based resin) The rubber composition of the present embodiment contains an alkylphenol-based resin. When the rubber composition contains an alkylphenol-based resin, the grip performance of the tire can be improved.

[0035] The content of the alkylphenol resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 12 parts by mass or more, per 100 parts by mass of the rubber component. By making the content equal to or greater than the lower limit, good grip performance tends to be obtained. Furthermore, the content of the alkylphenol resin is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the rubber component. By making the content equal to or less than the upper limit, good wear resistance tends to be ensured.

[0036] The softening point of the alkylphenol resin is preferably 100 to 160° C. The upper limit of the softening point is more preferably 150° C. or lower, and the lower limit is more preferably 130° C. or higher. In this specification, the softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0037] The alkylphenol resin is not particularly limited, and examples thereof include alkylphenol-aldehyde condensation resins obtained by reacting alkylphenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst; alkylphenol-alkyne condensation resins obtained by reacting alkylphenol with alkynes such as acetylene; and modified alkylphenol resins obtained by modifying these resins with compounds such as cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resin, aniline, and melamine. Among these, alkylphenol-alkyne condensation resins are preferred as the alkylphenol resin, and alkylphenol-acetylene condensation resins are particularly preferred.

[0038] Examples of alkylphenols constituting the alkylphenol resin include cresol, xylenol, t-butylphenol, octylphenol, nonylphenol, etc. Among these, phenols having a branched alkyl group such as t-butylphenol are preferred, and t-butylphenol is particularly preferred.

[0039] Commercially available alkylphenol resins include, for example, products under the trade name "HITANOL 1502P" (alkylphenol formaldehyde resin, manufactured by Hitachi Chemical Co., Ltd.), "TACKIROL 201" (alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), "TACKIROL 250-I" (brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), "TACKIROL 250-III" (brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), and products under the trade names "R7521P," "SP1068," "R7510PJ," "R7572P," and "R7578P" (manufactured by SI GROUP INC.).

[0040] (Hydrogenated Resin) The rubber composition of the present embodiment contains a hydrogenated resin. When the rubber composition contains a hydrogenated resin, the grip performance of the tire can be improved.

[0041] The hydrogenated resin preferably has a softening point higher than 110°C and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol. By applying a rubber composition containing such a hydrogenated resin to a tire, the grip performance of the tire can be further improved.

[0042] From the viewpoint of the fracture resistance of the tire, the softening point of the hydrogenated resin is preferably 116° C. or higher, more preferably 120° C. or higher, more preferably 123° C. or higher, more preferably 126° C. or higher, and even more preferably 128° C. or higher. From the viewpoint of the grip performance of the tire, the softening point of the hydrogenated resin is preferably 160° C. or lower, more preferably 150° C. or lower, more preferably 145° C. or lower, more preferably 141° C. or lower, and even more preferably 136° C. or lower.

[0043] From the viewpoints of suppressing precipitation of the hydrogenated resin from the tire and suppressing deterioration of the tire appearance, the polystyrene-equivalent weight average molecular weight of the hydrogenated resin is more preferably 300 g / mol or more, more preferably 400 g / mol or more, more preferably 500 g / mol or more, more preferably 550 g / mol or more, more preferably 600 g / mol or more, more preferably 650 g / mol or more, and even more preferably 700 g / mol or more. Furthermore, from the viewpoint of improving the compatibility of the hydrogenated resin with the rubber component and further enhancing the effects of the hydrogenated resin, the polystyrene-equivalent weight average molecular weight of the hydrogenated resin is more preferably 1570 g / mol or less, more preferably 1530 g / mol or less, more preferably 1500 g / mol or less, more preferably 1470 g / mol or less, more preferably 1430 g / mol or less, more preferably 1400 g / mol or less, more preferably 1370 g / mol or less, more preferably 1330 g / mol or less, more preferably 1300 g / mol or less, more preferably 1200 g / mol or less, more preferably 1100 g / mol or less, more preferably 1000 g / mol or less, and even more preferably 950 g / mol or less.

[0044] The weight average molecular weight (Mw) of the hydrogenated resin in terms of polystyrene ＨＲ ) (unit: g / mol) of the hydrogenated resin to the softening point (Ts ＨＲ ) (unit: °C) ratio (Ts ＨＲ / Mw ＨＲ ) is preferably 0.075 or more, more preferably 0.083 or more, more preferably 0.095 or more, more preferably 0.104 or more, more preferably 0.125 or more, more preferably 0.135 or more, more preferably 0.14 or more, and even more preferably 0.141 or more. ＨＲ / Mw ＨＲThe softening point and polystyrene-equivalent weight average molecular weight of the hydrogenated resin can be determined by the method described in the Examples below.

[0045] The content of the hydrogenated resin is preferably 10 parts by mass or more per 100 parts by mass of the rubber component. When the content of the hydrogenated resin in the rubber composition is 10 parts by mass or more per 100 parts by mass of the rubber component, the effect of improving the grip performance of the tire is greater. From the viewpoint of the grip performance of the tire, the content of the hydrogenated resin in the rubber composition is more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of the low-temperature embrittlement of the rubber composition, the content of the hydrogenated resin in the rubber composition is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less per 100 parts by mass of the rubber component.

[0046] The hydrogenated resin mentioned above refers to a resin obtained by reducing and hydrogenating a resin. Examples of resins that can be used as raw materials for the hydrogenated resin include C5 resins, C5-C9 resins, C9 resins, terpene resins (including terpene-aromatic compound resins), and dicyclopentadiene resins. These resins may be used alone or in combination of two or more.

[0047] Examples of the C5 resin include aliphatic petroleum resins obtained by (co)polymerizing C5 fractions obtained by thermal cracking of naphtha in the petrochemical industry. C5 fractions typically include olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. Commercially available C5 resins can be used.

[0048] The C5-C9 resin refers to a C5-C9 synthetic petroleum resin, and examples of the C5-C9 resin include a petroleum-derived C5-C11 fraction that is treated with AlCl ３ , B.F. ３Examples of suitable C5-C9 resins include solid polymers obtained by polymerization using a Friedel-Crafts catalyst such as styrene, vinyl toluene, α-methyl styrene, indene, etc., and more specifically, copolymers containing styrene, vinyl toluene, α-methyl styrene, indene, etc. as the main component. As the C5-C9 resin, a resin with a low content of C9 or higher components is preferred from the viewpoint of compatibility with the rubber component. Here, "low content of C9 or higher components" means that the content of C9 or higher components in the total amount of the resin is less than 50% by mass, preferably 40% by mass or less. Commercially available C5-C9 resins can be used.

[0049] The C9 resin refers to a C9 synthetic petroleum resin, such as AlCl ３ or BF ３ It refers to a solid polymer obtained by polymerizing a C9 fraction using a Friedel-Crafts catalyst such as: C9 resin, C9 copolymer, C9 copolymer having as its main component indene, α-methylstyrene, vinyltoluene, etc.

[0050] The terpene resin is a solid resin obtained by blending turpentine, which is obtained simultaneously with the extraction of rosin from pine trees, or a polymerization component separated therefrom, and polymerizing the blend using a Friedel-Crafts catalyst. Examples of such resins include β-pinene resin and α-pinene resin. Terpene resins also include terpene-aromatic compound resins, representative examples of which include terpene-phenol resin and styrene-terpene resin. Terpene-phenol resins can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing the terpene with formalin. Styrene-terpene resins can be obtained by reacting styrene with terpenes using a Friedel-Crafts catalyst. The terpenes used as raw materials are not particularly limited; monoterpene hydrocarbons such as α-pinene and limonene are preferred, with those containing α-pinene being more preferred, and α-pinene being particularly preferred.

[0051] The dicyclopentadiene resin is, for example, AlCl ３ or BF ３This refers to a resin obtained by polymerizing dicyclopentadiene using a Friedel-Crafts catalyst such as

[0052] Furthermore, the resin used as the raw material for the hydrogenated resin may contain, for example, a resin obtained by copolymerizing a C5 fraction with dicyclopentadiene (DCPD) (C5-DCPD resin). Here, when the dicyclopentadiene-derived component is 50% by mass or more in the total amount of resin, the C5-DCPD resin is considered to be included in the dicyclopentadiene-based resin. When the dicyclopentadiene-derived component is less than 50% by mass in the total amount of resin, the C5-DCPD resin is considered to be included in the C5-based resin. The same applies to cases where a small amount of a third component or the like is further contained.

[0053] From the viewpoint of increasing the compatibility between the rubber component and the hydrogenated resin and further improving the grip performance of a tire using the rubber composition, the hydrogenated resin is preferably at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated dicyclopentadiene resins (hydrogenated DCPD resins), and hydrogenated terpene resins. When the hydrogenated resin is one of these resins, the grip performance of the tire can be further improved. Furthermore, the hydrogenated resin is more preferably at least one selected from the group consisting of hydrogenated C5 resins and hydrogenated C5-C9 resins, and even more preferably a hydrogenated C5 resin. Furthermore, the hydrogenated resin is preferably a resin having a hydrogenated DCPD structure or a hydrogenated cyclic structure in at least one monomer. The hydrogenated resins may be used alone or in combination of two or more.

[0054] (Other Resins) The rubber composition of the present embodiment may contain other resins in addition to the alkylphenol resin and the hydrogenated resin. Examples of other resins include aromatic hydrocarbon resins, aliphatic hydrocarbon resins, and alicyclic hydrocarbon resins.

[0055] Aromatic hydrocarbon resins are cyclic unsaturated organic compounds. Examples of aromatic hydrocarbon resins include resins obtained by polymerizing vinyl-substituted aromatic hydrocarbons such as α-methylstyrene, o-vinyltoluene, m-vinyltoluene, and p-vinyltoluene contained in the C5-C10 fraction (particularly the C9 fraction) obtained by thermal decomposition of naphtha.

[0056] Aliphatic hydrocarbon resins are linear or cyclic non-aromatic hydrocarbon resins, and the bonds between carbon atoms in the aliphatic hydrocarbon resins may all be single bonds, or may have unsaturated bonds such as double or triple bonds.

[0057] Alicyclic hydrocarbon resins refer to aliphatic hydrocarbons with cyclic molecular shapes, and include cycloalkanes, which are cyclic compounds with single bonds, cycloalkenes, which are cyclic compounds with double bonds, and cycloalkynes, which are cyclic compounds with triple bonds. Dicyclopentadiene resins are particularly suitable as alicyclic hydrocarbon resins.

[0058] (Liquid Softener Component) The rubber composition of this embodiment may contain a liquid softener component. The liquid softener component is liquid at 25°C (room temperature). By applying a rubber composition containing such a liquid softener component to a tire, the grip performance of the tire can be improved. Here, examples of the liquid softener component include oil and liquid polymer. The liquid softener component may be used alone or in combination of two or more.

[0059] The oil is a general term for extender oil contained in the rubber component and liquid oil added as a compounding agent to the rubber composition, and includes petroleum-based softeners such as aromatic oil, paraffinic oil, and naphthenic oil; and vegetable-based softeners such as palm oil, castor oil, cottonseed oil, and soybean oil. Of these, petroleum-based softeners such as aromatic oil, paraffinic oil, and naphthenic oil are preferred. From the viewpoint of workability, the mass ratio of extender oil to compounding agent oil is preferably 1:1 to 10:1.

[0060] The amount of oil is preferably 10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component.

[0061] The liquid polymer is preferably liquid at 25° C. (room temperature) and has a weight average molecular weight of 5,000 to 100,000. Examples of such liquid polymers include liquid polybutadiene, liquid polyisoprene, and liquid polystyrene-butadiene.

[0062] The content of the liquid softener component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and preferably 90 parts by mass or less, more preferably 70 parts by mass or less, per 100 parts by mass of the rubber component. When the content of the liquid softener component in the rubber composition is 30 parts by mass or more per 100 parts by mass of the rubber component, the effect of improving the grip performance of the tire is increased, while when it is 90 parts by mass or less, the workability in manufacturing the rubber composition is improved.

[0063] (Filler) The rubber composition of the present embodiment preferably further contains a filler. The filler preferably contains carbon black, more preferably carbon black and silica. The filler may also contain fillers other than carbon black and silica. The filler can reinforce the rubber composition and improve the fracture resistance of the rubber composition.

[0064] The total content of the fillers is preferably 100 parts by mass or more per 100 parts by mass of the rubber component. When the total content of the fillers is 100 parts by mass or more per 100 parts by mass of the rubber component, the effect of improving the grip performance of the tire is further enhanced. Furthermore, the total content of the fillers is preferably 140 parts by mass or less per 100 parts by mass of the rubber component. When the total content of the fillers is 140 parts by mass or less per 100 parts by mass of the rubber component, the abrasion resistance of the rubber composition is improved. The total content of the fillers is more preferably 115 parts by mass or more, and more preferably 130 parts by mass or less per 100 parts by mass of the rubber component.

[0065] [Carbon Black] The filler preferably contains carbon black. Carbon black reinforces the rubber composition and can improve the fracture resistance of the rubber composition. Carbon black also contributes to improving the grip performance of a tire to which the rubber composition is applied, thereby enabling the tire to achieve both high levels of grip performance and fracture resistance.

[0066] The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more.

[0067] From the viewpoints of the fracture resistance of the rubber composition and the grip performance of a tire using the rubber composition, the content of carbon black in the rubber composition is preferably 70 parts by mass or more, and more preferably 75 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of the abrasion resistance of the rubber composition, the content of carbon black in the rubber composition is preferably 120 parts by mass or less, and more preferably 110 parts by mass or less, per 100 parts by mass of the rubber component.

[0068] Carbon black has a nitrogen adsorption specific surface area (N ２ SA) is 80m ２ / g or more, and ２ / g or more is more preferable, and 120m ２ / g or more. ２ SA) is 200m ２ / g or less, and ２ / g or less is more preferable, and 150m ２ The nitrogen adsorption specific surface area of ​​carbon black can be measured in accordance with JIS K6217-2:2001.

[0069] [Silica] The filler preferably contains silica. Furthermore, the filler more preferably contains silica in addition to carbon black. Silica can improve the grip performance of a tire to which the rubber composition is applied.

[0070] The silica has a nitrogen adsorption specific surface area (BET method) of 80 m ２ / g or more 330m ２ The nitrogen adsorption specific surface area (BET method) of silica is preferably less than 80 m ２ / g or more, a tire using the rubber composition can be sufficiently reinforced. ２ When the specific surface area of ​​silica is less than 100 m / g, the elastic modulus of the rubber composition does not become too high, and the grip performance of a tire using the rubber composition is improved. ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ From the viewpoint of further improving the grip performance of the tire, the nitrogen adsorption specific surface area (BET method) of the silica is more preferably 300 m ２ / g or less, and ２ / g or less is more preferable, and 270m ２ The silica preferably has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 150 m ２ / g or more, more preferably 150 to 300m ２ / g, and even more preferably 150 to 250 m ２ / g, particularly preferably 150 to 220 m ２ / g. CTAB is 150m２ When the CTAB is 300 m / g or more, a tire to which the rubber composition is applied can be sufficiently reinforced. ２ When the modulus of elasticity of the rubber composition is not too high, the wet grip performance of a tire using the rubber composition is improved.

[0071] Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate, and among these, wet silica is preferred. These silicas may be used alone or in combination of two or more.

[0072] From the viewpoint of tire grip performance, the content of silica in the rubber composition is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of the abrasion resistance of the rubber composition, the content of silica in the rubber composition is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, per 100 parts by mass of the rubber component.

[0073] [Other Fillers] The filler may include other fillers such as clay, talc, calcium carbonate, and aluminum hydroxide in addition to carbon black and silica.

[0074] (Styrenic Thermoplastic Elastomer) The rubber composition of this embodiment may contain a styrene-based thermoplastic elastomer (TPS). The styrene-based thermoplastic elastomer (TPS) has a styrene-based polymer block (hard segment) and a conjugated diene-based polymer block (soft segment). The styrene-based polymer portion forms physical crosslinks to serve as crosslinking points, while the conjugated diene-based polymer block imparts rubber elasticity. The double bonds of the conjugated diene-based polymer block (soft segment) may be partially or completely hydrogenated. Note that while the styrene-based thermoplastic elastomer (TPS) is thermoplastic, the rubber component is not. Therefore, in this specification, the styrene-based thermoplastic elastomer (TPS) is not included in the rubber component. The content of the styrene-based thermoplastic elastomer (TPS) is preferably in the range of 1 to 30 parts by mass per 100 parts by mass of the rubber component.

[0075] Examples of the styrene-based thermoplastic elastomer (TPS) include styrene / butadiene / styrene (SBS) block copolymer, styrene / isoprene / styrene (SIS) block copolymer, styrene / butadiene / isoprene / styrene (SBIS) block copolymer, styrene / isoprene (SI) block copolymer, styrene / butadiene / isoprene (SBI) block copolymer, styrene / ethylene / butylene / styrene (SEBS) block copolymer, styrene / ethylene / propylene / styrene (SEPS) block copolymer, styrene / ethylene / ethylene / propylene / styrene (SEEPS) block copolymer, styrene / ethylene / butylene (SEB) block copolymer, styrene / ethylene / propylene (SEP) block copolymer, and styrene / ethylene / ethylene / propylene (SEEP) block copolymer.

[0076] (Other Components) In addition to the rubber components described above, the rubber composition of the present embodiment may contain, as necessary, various components commonly used in the rubber industry, such as a silane coupling agent, an antioxidant, stearic acid, zinc oxide (zinc white), a vulcanization accelerator, a vulcanizing agent, etc., appropriately selected within a range that does not impair the object of the present invention. Commercially available products can be suitably used as these compounding ingredients.

[0077] Examples of silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, Examples of the silane coupling agent include N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide. The amount of the silane coupling agent is preferably in the range of 2 to 20 parts by mass, more preferably 5 to 15 parts by mass, per 100 parts by mass of silica.

[0078] Examples of the antioxidant include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6C), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), N,N'-diphenyl-p-phenylenediamine (DPPD), etc. The content of the antioxidant is not particularly limited, and is preferably in the range of 0.1 to 15 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0079] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiuram-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators. Examples of the vulcanizing agent include sulfur. The total content of the vulcanization system (vulcanization package) containing the vulcanization accelerator, vulcanizing agent, and stearic acid is not particularly limited, and is preferably in the range of 1 to 25 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the rubber component.

[0080] (Method for Producing Rubber Composition) The method for producing the rubber composition of the present embodiment is not particularly limited, but for example, the rubber composition can be produced by blending various components appropriately selected as necessary with the above-mentioned rubber component containing styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more, alkylphenol resin, and hydrogenated resin, and kneading, heating, extruding, etc. Furthermore, the obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0081] The kneading conditions are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0082] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0083] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0084] The vulcanization equipment, method, conditions, etc. are not particularly limited and can be appropriately selected depending on the purpose. Examples of equipment for vulcanization include a molding vulcanizer using a mold used for vulcanizing rubber compositions. The vulcanization temperature is, for example, about 100 to 190°C.

[0085] (Uses) The rubber composition of the present embodiment can be used for various tire components including tire tread rubber, and is particularly suitable for tire tread rubber.

[0086] <Tread Rubber> The tread rubber of this embodiment is characterized by being made of the rubber composition described above. Since this tread rubber is made of the rubber composition of this embodiment, it is possible to achieve both tire grip performance and fracture resistance. The tread rubber of this embodiment may be applied to new tires or retread tires.

[0087] <Tire> The tire of this embodiment is characterized by including the above-mentioned tread rubber. Since the tire includes the tread rubber made of the rubber composition of this embodiment, both grip performance and fracture resistance are achieved.

[0088] The tire of this embodiment may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization step or the like and then further vulcanizing it. The tire of the present invention is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0090] <Preparation of Rubber Composition> Rubber compositions were prepared by kneading the ingredients according to the formulations shown in Table 1 using a conventional kneading device.

[0091] <Measurement Methods and Evaluation Methods> The following measurement methods and evaluation methods were used.

[0092] (Method for Analyzing Styrene-Butadiene Rubber) -Weight-Average Molecular Weight of Styrene-Butadiene Rubber- The weight-average molecular weight of styrene-butadiene rubber was determined by gel permeation chromatography (GPC) under the following conditions. Using a GPC measurement device (manufactured by Tosoh Corporation, trade name "HLC-8320GPC") in which three columns packed with polystyrene gel were connected, a chromatogram was measured using an RI detector (manufactured by Tosoh Corporation, trade name "HLC8020"), and the weight-average molecular weight (Mw) was determined based on a calibration curve obtained using standard polystyrene. The eluent used was THF (tetrahydrofuran) containing 5 mmol / L triethylamine. Three columns, trade name "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation, were connected, and a guard column, trade name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation, was connected in front of them. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min.

[0093] (Method of Analyzing Hydrogenated Resin) The softening point and weight average molecular weight of the hydrogenated resin were measured by the following method.

[0094] -Softening Point- The softening point of the hydrogenated resin was measured in accordance with JIS-K2207-1996 (ring and ball method).

[0095] -Weight-average molecular weight- The average molecular weight of the hydrogenated resin was measured by gel permeation chromatography (GPC) under the following conditions, and the weight-average molecular weight in terms of polystyrene was calculated: Column temperature: 40°C Injection volume: 50 μL Carrier and flow rate: tetrahydrofuran 0.6 mL / min Sample preparation: About 2.5 mg of the resin component was dissolved in 10 mL of tetrahydrofuran.

[0096] (Evaluation of Rubber Composition) The grip performance and fracture resistance of each prepared rubber composition were evaluated by the following method. The grip performance and fracture resistance were evaluated using an index, and when each index was 90 or more and the total index was more than 200, it was considered that both grip performance and fracture resistance were achieved.

[0097] -Grip Performance- The loss tangent (tan δ) of the rubber composition was measured using a Metravib manufactured by Acoem at a frequency of 100 Hz, a stress of 0.3 MPa, and a temperature of 50°C, and expressed as an index, with the tan δ of Comparative Example 1 set at 100. The larger the index value, the larger the tan δ and the better the grip performance. The evaluation results are shown in Table 1.

[0098] - Puncture resistance - The obtained rubber composition was vulcanized by a conventional method to produce a vulcanized rubber, and a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K 6251:2004. A tensile test was performed on the test piece in accordance with JIS K 6251:2004 to measure the tensile stress at break (TB) at a temperature of 25°C, and the tensile stress at break (TB) of Comparative Example 1 was set to 100, and each value was expressed as an index. A larger index value indicates a larger tensile stress at break (TB) and better fracture resistance. The evaluation results are shown in Table 1.

[0099]

[0100] *1 SBR1: Styrene-butadiene rubber, manufactured by Asahi Kasei Corporation, trade name "Tufden 1834", weight average molecular weight (Mw) = 652,000, styrene bond amount = 18 mass%, oil-extended rubber containing 37.5 mass parts of extender oil (liquid softener component, liquid at 25 ° C) per 100 mass parts of rubber component, the upper row indicates the content of rubber component, and the lower row indicates the content of extender oil. *2 SBR2: Styrene-butadiene rubber, manufactured by ENEOS Materials Corporation, trade name "HP755B", S-SBR, weight average molecular weight (Mw) = 1048,000, styrene bond amount = 40 mass%, oil-extended rubber containing 37.5 mass parts of extender oil (liquid softener component, liquid at 25 ° C) per 100 mass parts of rubber component, the upper row indicates the content of rubber component, and the lower row indicates the content of extender oil. *3 SBR3: Styrene-butadiene rubber, manufactured by Asahi Kasei Corporation, trade name "Tufden 3835", weight average molecular weight (Mw) = 898,000, styrene bond amount = 38 mass%, oil-extended rubber containing 37.5 mass parts of extender oil (liquid softener component, liquid at 25 ° C) per 100 mass parts of rubber component, the upper row shows the content of the rubber component, and the lower row shows the content of the extender oil. *4 SBR4: Styrene-butadiene rubber, manufactured by Asahi Kasei Corporation, trade name "Tufden E581", weight average molecular weight (Mw) = 1158,000, styrene bond amount = 38 mass%, oil-extended rubber containing 37.5 mass parts of extender oil (liquid softener component, liquid at 25 ° C) per 100 mass parts of rubber component, the upper row shows the content of the rubber component, and the lower row shows the content of the extender oil. *5 SBR5: Styrene-butadiene rubber, S-SBR, manufactured by ENEOS Materials Corporation, trade name "HPR520", weight average molecular weight (Mw) = 276,000, bound styrene content = 35% by mass *6 SBR6: Styrene-butadiene rubber, E-SBR, manufactured by ENEOS Materials Corporation, trade name "T0150", weight average molecular weight (Mw) = 949,000, bound styrene content = 46% by mass, oil-extended rubber containing 34 parts by mass of extender oil (liquid softener component, liquid at 25 ° C) per 100 parts by mass of rubber component, the upper row indicates the content of the rubber component, and the lower row indicates the content of the extender oil. *7 Carbon black: manufactured by Tokai Carbon Co., Ltd., trade name "Seat 600P", nitrogen adsorption specific surface area (BET method) = 142 m ２ / g *8 Silica: Tosoh Silica Corporation, trade name "Nipsil AQ", nitrogen adsorption specific surface area (BET method) = 210 m ２ / g, cetyltrimethylammonium bromide adsorption specific surface area (CTAB) = 155 m ２ / g * 9 Oil 1: Idemitsu Kosan Co., Ltd., trade name "Diana Process NS-70S" * 10 Oil 2: Kao Corporation, trade name "R-400" * 11 Resin 1: Alkylphenol resin, BASF Corporation, trade name "KORESIN" * 12 Resin 2: Aromatic hydrocarbon resin, ENEOS Corporation, trade name "Nippon Oil Neopolymer 140" * 13 Resin 3: Hydrogenated C5 resin, Eastman Corporation, trade name "Trademark Impera E1780", softening point = 130 ° C., weight average molecular weight (Mw) = 909 g / mol * 14 Other components: silane coupling agent, silane coupling agent, stearic acid, wax, antioxidant, zinc oxide, vulcanization accelerator and sulfur total amount

[0101] It can be seen from Table 1 that the rubber compositions of the examples according to the present invention are able to achieve both good grip performance and good fracture resistance.

[0102] According to the present invention, it is possible to provide a rubber composition that can achieve both grip performance and fracture resistance.

Claims

1. A rubber composition comprising: a rubber component containing a styrene-butadiene rubber having a weight average molecular weight (Mw) of 660,000 or more; an alkylphenol resin; and a hydrogenated resin.

2. The rubber composition according to claim 1, wherein the hydrogenated resin has a softening point higher than 110°C and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol.

3. The rubber composition according to claim 1, wherein the hydrogenated resin is at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated dicyclopentadiene resins, and hydrogenated terpene resins.

4. The rubber composition according to claim 1, further comprising a filler, said filler comprising carbon black.

5. The rubber composition according to claim 4, wherein the filler further comprises silica.

6. The rubber composition according to claim 5, wherein the total content of the filler is 100 parts by mass or more per 100 parts by mass of the rubber component.

7. The rubber composition according to claim 1, wherein the content of the alkylphenol resin is 10 parts by mass or more per 100 parts by mass of the rubber component.

8. The rubber composition according to claim 1, wherein the content of the hydrogenated resin is 10 parts by mass or more per 100 parts by mass of the rubber component.

9. A tread rubber comprising the rubber composition according to claim 1.

10. A tire comprising the tread rubber according to claim 9.

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