Rubber composition for tires and tires

Abstract

The present invention provides a tire rubber composition that maintains or improves the overall performance of rolling resistance, wet grip performance, and wear resistance, while replacing aromatic softeners with sustainable raw materials. [Solution] The tire rubber composition according to the embodiment comprises a rubber component, a naturally derived liquid resin, and a sustainable oil. The naturally derived liquid resin is included in such a way that its mass ratio to the sustainable oil is 1 to 4.

Description

Technical Field

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

Background Art

[0002] It is known to blend vegetable oil or liquid resin into a rubber composition. For example, Patent Document 1 discloses a rubber composition for tires that can improve the riding comfort when driving on rough roads, and it describes blending sunflower oil and C5 / C9 resin into the rubber composition.

[0003] Patent Documents 2 and 3 disclose a rubber composition that has a small environmental impact and excellent resistance to vulcanization reversion, and it describes blending soybean oil as a softening agent and a liquid terpene resin as a tackifier into the rubber composition.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Recently, efforts to reduce dependence on petroleum and promote the sustainable use of naturally derived resources have become more active, and sustainable raw materials such as biomass-derived and recycled-derived raw materials are attracting attention. Currently, aromatic softeners derived from petroleum are mainly used as tire softeners, so the development of tire rubber compositions that replace aromatic softeners with sustainable raw materials is desirable from a sustainability perspective. When considering sustainable raw materials that can function as substitutes for aromatic softeners, it is desirable that they do not degrade various physical properties of vulcanized rubber compared to when aromatic softeners are used as before.

[0006] In view of the above, embodiments of the present invention aim to provide a tire rubber composition in which an aromatic softener is replaced with a sustainable raw material, and a tire using the same, while maintaining or improving the overall performance of rolling resistance, wet grip performance, and wear resistance. [Means for solving the problem]

[0007] The present invention includes embodiments shown below. [1] A rubber composition for tires comprising a rubber component, a naturally derived liquid resin, and a sustainable oil, wherein the mass ratio of the naturally derived liquid resin to the sustainable oil is 1 to 4. [2] The tire rubber composition according to [1], wherein the sustainable oil comprises a vegetable oil. [3] The tire rubber composition according to [1] or [2], wherein the total content of the naturally derived liquid resin and the sustainable oil per 100 parts by mass of the rubber component is 5 to 80 parts by mass. [4] A tire having a rubber portion made using a tire rubber composition described in any one of items [1] to [3]. [Effects of the Invention]

[0008] According to embodiments of the present invention, it is possible to provide a tire rubber composition in which aromatic softeners are replaced with sustainable raw materials while maintaining or improving the overall performance of rolling resistance, wet grip performance, and wear resistance, and a tire using the same. [Modes for carrying out the invention]

[0009] The inventors diligently investigated sustainable raw materials that can function as a substitute for aromatic softeners without degrading various physical properties of vulcanized rubber. As a result, they found that when a natural liquid resin and sustainable oil are blended in a specific ratio instead of aromatic softeners, the overall performance of the vulcanized rubber in terms of rolling resistance, wet grip performance, and abrasion resistance becomes equivalent to or better than that of the original material.

[0010] The rubber composition for tires according to this embodiment (hereinafter also simply referred to as "rubber composition") comprises (A) a rubber component, (B) a naturally derived liquid resin, and (C) a sustainable oil.

[0011] [(A) Rubber component] In this embodiment, the rubber component is not particularly limited, and various diene rubbers commonly used in tire rubber compositions can be used. A diene rubber is a rubber having repeating units corresponding to a diene monomer having a conjugated double bond, and the main chain of the polymer contains a carbon-carbon double bond. The content of diene rubber in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass.

[0012] Specific examples of diene rubbers include natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), chloroprene rubber (CR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, and styrene-isoprene-butadiene copolymer rubber. These diene rubbers also include those modified by introducing functional groups to the ends or main chain as needed, or those modified to impart desired properties. The functional groups preferably contain oxygen and / or nitrogen atoms, and examples include at least one selected from the group consisting of amino groups, hydroxyl groups, alkoxy groups, alkoxysilyl groups, epoxy groups, and carboxyl groups. These diene rubbers may be used individually or in combination of two or more types.

[0013] In one embodiment, the rubber component may include styrene-butadiene rubber (SBR), for example, styrene-butadiene rubber (SBR) alone, or SBR in combination with natural rubber (NR) or butadiene rubber (BR). 100 parts by mass of the rubber component may contain 30 to 100 parts by mass of SBR and 0 to 70 parts by mass of NR or BR, or 50 to 100 parts by mass of SBR and 0 to 50 parts by mass of NR or BR.

[0014] [(B) Naturally derived liquid resin] The rubber composition according to this embodiment contains a naturally derived liquid resin. In this invention, a naturally derived liquid resin refers to a resin whose main component is a naturally derived component and which is fluid at room temperature (25°C). Here, naturally derived components refer to components derived from living organisms such as plants and animals, and do not include petroleum-derived components.

[0015] The content of naturally derived components in the naturally derived liquid resin is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may even be 100% by mass.

[0016] Examples of naturally derived liquid resins include terpene resins and rosin resins that are fluid at room temperature (25°C), i.e., liquid terpene resins and liquid rosin resins. These may be used individually or in combination of two or more types.

[0017] Terpene resins are resins made from at least one terpene compound selected from terpene compounds, and have units derived from terpene compounds. Terpene compounds are (C5H8) n Terpene compounds are hydrocarbons represented by the following composition and their oxygen-containing derivatives, and are compounds based on terpenes, which are classified as monoterpenes, sesquiterpenes, diterpenes, etc. Specific examples of terpene compounds include α-pinene, β-pinene, 3-carene (δ-3-carene), dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, and others.

[0018] Polyterpene resins are a specific example of terpene resins. Polyterpene resins are resins obtained by polymerizing only the above-mentioned terpene compounds, and these also include hydrogenated compounds. Specific examples of terpene resins may also include modified terpene resins obtained by copolymerization or other means (phenol modification, aromatic modification, hydrocarbon modification, etc.) (e.g., terpene-phenol resins, styrene-modified terpene resins, aromatic-modified terpene resins, etc.). Polyterpene resins are particularly preferred as terpene resins. That is, liquid polyterpene resins are particularly preferred as liquid terpene resins.

[0019] Rosin-based resins are resins that use rosin as a base. Rosin is a natural resin obtained from pine plants and contains abietic acid and its isomers in various proportions. Other components of rosin besides abietic acid include dehydroabietic acid, dihydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, levopimaric acid, and palastic acid.

[0020] Specific examples of rosin-based resins include rosin such as gum rosin and wood rosin, disproportionated rosin obtained by dehydrogenation and disproportionation reactions of raw rosin, hydrogenated rosin obtained by hydrogenating raw rosin, rosins such as polymerized rosin obtained by polymerization of raw rosin, rosin ester resins obtained by esterifying rosins and polyols, phenol-modified rosins, unsaturated acid-modified rosins, formylated rosins obtained by reducing rosins, and the like.

[0021] [(C) Sustainable Oil] The rubber composition according to this embodiment contains sustainable oil. In the present invention, sustainable oil refers to fats and oils obtained from sustainable raw materials such as raw materials derived from biomass resources and raw materials derived from recycled resources. Specifically, vegetable oils, animal oils, and pyrolysis oils are included. The sustainable oil may be solid or liquid at normal temperature (25°C). "Solid state" refers to a state without fluidity, and "liquid state" refers to a state with fluidity. The sustainable oil may be used alone or in combination of two or more.

[0022] Vegetable oil refers to fats and oils extracted from plant seeds, fruits, kernels, etc., and also includes those obtained by treating these fats and oils by various methods. Specifically, refined oils obtained by refining vegetable oils, recycled oils made reusable by removing deteriorated products and foreign substances contained in used and deteriorated vegetable oils, ester-exchanged oils obtained by ester-exchanging vegetable oils, hydrogenated oils obtained by hydrogenating vegetable oils, oxidative polymerization oils obtained by oxidizing vegetable oils, thermally polymerized oils obtained by thermally polymerizing vegetable oils, and the like.

[0023] Specific examples of vegetable oils include linseed oil, avocado oil, corn oil, pine oil, coconut oil, olive fruit oil, rapeseed oil, safflower oil, sunflower oil, southern magnolia oil, cottonseed oil, rice bran oil, sesame oil, perilla oil, castor oil, tung oil, palm oil, palm kernel oil, camellia seed oil, jojoba oil, soybean oil, macadamia nut oil, hazelnut oil, peanut oil, grape seed oil, palm oil, tall oil, wood wax, and the like.

[0024] The above-mentioned vegetable oils are classified into non-drying oils, semi-drying oils, and drying oils according to their iodine value. Vegetable oils with an iodine value of 100 or less are called non-drying oils, those with an iodine value between 100 and 130 are called semi-drying oils, and those with an iodine value of 130 or more are called drying oils. Here, the iodine value is the value obtained by converting the amount of halogen that binds when a halogen is reacted with 100g of the sample into the amount of iodine (g), and is measured in accordance with JIS K0070:1992.

[0025] In one embodiment, a vegetable oil with a low iodine value, i.e., a non-drying oil, may be used. Using a non-drying oil allows for a longer scorch time of the rubber composition, resulting in superior processability. Specific examples of non-drying oils include palm oil, palm kernel oil, coconut oil, macadamia nut oil, hazelnut oil, castor oil, camellia seed oil, olive fruit oil, sasanqua oil, avocado oil, and sunflower oil (high-oleic sunflower oil).

[0026] Examples of animal oils include fish oil, fatty oils (liver oil) obtained from the livers of fish such as cod and sharks, marine animal oils such as whale and seal oil, land animal oils such as beef tallow and pork tallow, and recycled oils that can be reused by removing degradation products and foreign matter contained in degraded animal oils using these materials.

[0027] Pyrolysis oil refers to oil obtained by thermally decomposing waste tires, and by refining the oil and other components contained in the waste tires. Conventional methods known can be used to produce pyrolysis oil, and the production method is not particularly limited.

[0028] In one embodiment, the sustainable oil preferably contains vegetable oil. The vegetable oil content in the sustainable oil is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and may even be 100% by mass.

[0029] In this embodiment, the naturally derived liquid resin and sustainable oil are included such that the mass ratio of the naturally derived liquid resin to the sustainable oil (naturally derived liquid resin / sustainable oil) is 1 to 4. The mass ratio (naturally derived liquid resin / sustainable oil) is preferably 1.5 to 3.5, and more preferably 2 to 3.

[0030] In one embodiment, the total content of naturally derived liquid resin and sustainable oil is preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 15 to 40 parts by mass, per 100 parts by mass of rubber component.

[0031] [Other ingredients] In addition to the components mentioned above, the rubber composition according to this embodiment may contain various additives commonly used in rubber compositions, such as fillers, silane coupling agents, solid resins, zinc oxide, stearic acid, waxes, processing aids, antioxidants, vulcanization accelerators, and sulfur.

[0032] Examples of fillers include carbon black and silica, which may be used individually or in combination.

[0033] The carbon black used is not particularly limited, and various known grades can be used. Specifically, examples include SAF grade (N100 series), ISAF grade (N200 series), HAF grade (N300 series), FEF grade (N500 series), GPF grade (N600 series), and SRF grade (N700 series) (all ASTM grades). These carbon blacks can be used individually or in combination of two or more. The carbon black content is not particularly limited; for example, in a compound where carbon black is the main filler, it may be 30 to 90 parts by mass, 40 to 85 parts by mass, or 50 to 80 parts by mass per 100 parts by mass of rubber component. In a compound where silica is the main filler, it may be 1 to 20 parts by mass, 2 to 15 parts by mass, or 3 to 10 parts by mass per 100 parts by mass of rubber component.

[0034] The silica is not particularly limited and includes wet silica, dry silica, etc. Preferably, wet silica such as wet sedimentation silica or wet gelation silica is used. The silica content is not particularly limited and may be 50 to 180 parts by mass, 70 to 160 parts by mass, 80 to 150 parts by mass, or 85 to 140 parts by mass per 100 parts by mass of rubber component.

[0035] When carbon black and silica are used together as fillers, the total amount of fillers is not particularly limited. For example, it may be 50 to 180 parts by mass, 70 to 160 parts by mass, 80 to 150 parts by mass, or 90 to 145 parts by mass per 100 parts by mass of rubber component.

[0036] When silica is incorporated into a rubber composition, a silane coupling agent may be used in combination. Examples of silane coupling agents include sulfide silane coupling agents, mercaptosilane coupling agents, and thioester group-containing silane coupling agents. The content of the silane coupling agent is not particularly limited and may be 5 to 20 parts by mass, 5 to 15 parts by mass, or 5 to 10 parts by mass per 100 parts by mass of silica.

[0037] As the solid resin, a resin that is solid at room temperature (25°C) is used, and examples include hydrocarbon resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic / aromatic hydrocarbon resins, styrene resins, acrylic resins, coumarone resins, terpene resins, and rosin resins. Any one or two or more of these can be used in combination. The content of the solid resin is not particularly limited, and for example, it may be 5 to 60 parts by mass, 10 to 50 parts by mass, or 20 to 40 parts by mass per 100 parts by mass of rubber component.

[0038] The zinc oxide content is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of rubber component.

[0039] The stearic acid content is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of rubber component.

[0040] The wax content is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of rubber component.

[0041] The amount of processing aids is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of rubber components.

[0042] Examples of anti-aging agents include amine-ketone, aromatic secondary amine, monophenol, bisphenol, and benzimidazole-based anti-aging agents, and any one or more of these can be used in combination. The content of the anti-aging agent is not particularly limited and may be 0 to 10 parts by mass, 1 to 8 parts by mass, or 2 to 5 parts by mass per 100 parts by mass of the rubber component.

[0043] Examples of vulcanization accelerators include sulfenamide-based, thiuram-based, thiazole-based, and guanidine-based vulcanization accelerators, which can be used individually or in combination of two or more. The content of the vulcanization accelerator is not particularly limited and may be 0 to 10 parts by mass, 1 to 8 parts by mass, or 3 to 6 parts by mass per 100 parts by mass of rubber component.

[0044] The sulfur content is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of rubber component.

[0045] The rubber composition according to this embodiment can be prepared by kneading in accordance with conventional methods using a commonly used mixer such as a Banbury mixer, kneader, or roll. That is, in the first mixing stage, additives other than the vulcanization accelerator and sulfur are added to the rubber component and mixed, and then, in the final mixing stage, the vulcanization accelerator and sulfur are added to the resulting mixture and mixed to prepare an unvulcanized rubber composition.

[0046] The rubber composition according to this embodiment can be used in various applications and sizes of pneumatic tires, such as passenger car tires and large tires for trucks and buses.

[0047] A tire according to one embodiment has a rubber portion made using the above-mentioned rubber composition. Examples of application parts of the tire include the tread, sidewall, and bead, and it is preferably used in the tread.

[0048] The tread rubber of a tire may have a two-layer structure consisting of a cap rubber and a base rubber, or a single-layer structure in which both are integrated. In the case of a single-layer structure, the tread rubber may be formed from the above-mentioned rubber composition. In the case of a two-layer structure, the outer cap rubber that contacts the road surface may be formed from the above-mentioned rubber composition, the base rubber placed inside the cap rubber may be formed from the above-mentioned rubber composition, or both the cap rubber and the base rubber may be formed from the above-mentioned rubber composition.

[0049] In one embodiment, the method for manufacturing a tire having a rubber portion made using the above rubber composition is not particularly limited. For example, the above rubber composition can be molded into a predetermined shape by extrusion according to a conventional method to obtain an unvulcanized rubber member (e.g., tread rubber, sidewall rubber, etc.). By combining this rubber member with other tire members, an unvulcanized tire (green tire) can be manufactured. Subsequently, the tire can be manufactured by vulcanization molding at, for example, 140 to 180°C. [Examples]

[0050] The following are examples of the present invention, but the present invention is not limited to these examples.

[0051] The raw materials used in the examples and comparative examples are as follows: • SBR-1: Unmodified ESBR, manufactured by ENEOS Material Co., Ltd. as "SBR1502" • SBR-2: Terminally modified SSBR, manufactured by ENEOS Material Co., Ltd., "HPR350" • SBR-3: Terminally modified SSBR, manufactured by ENEOS Material Co., Ltd., "HPR840" • BR-1: Modified BR, manufactured by Nippon Zeon Co., Ltd. "Nipol BR1261" • BR-2: Unmodified BR, Lanxess "Buna CB22" • BR-3: Unmodified BR, manufactured by UBE Elastomer Co., Ltd. "UBEPOL BR 150B" • NR: RSS#3 • Carbon Black: "Seast KH" manufactured by Tokai Carbon Co., Ltd. • Silica: "ULTRASIL VN3" manufactured by Evonik Industries. • Silane coupling agent-1: Evonik Industries "Si69" • Silane coupling agent-2: MOMENTIVE's "NXT" • Aromatic oil: Process NC-140 manufactured by ENEOS Corporation • Sustainable Oil-1: Palm oil, manufactured by Nisshin Oillio Group Ltd., "PL65" (iodine value = 65) • Sustainable Oil-2: High-oleic sunflower oil, manufactured by Nisshin Oillio Group Ltd. ("Nisshin Sunflower Oil" (iodine value = 84)) • Liquid resin-1: Liquid pinene resin, "Dercolyte LTG" manufactured by DRT. • Liquid resin-2: Liquid rosin ester resin, "Hercolyn D" manufactured by DRT. • Solid resin-1: Polyterpene resin, Kraton "SYLVATRAXX 4150" • Solid resin-2: Alpha-methylstyrene resin, Kraton "SYLVATRAXX 4401" • Zinc oxide: "Zinc Oxide Type 2" manufactured by Mitsui Mining & Smelting Co., Ltd. • Stearic acid: "Bead Stearic Acid" manufactured by NOF Corporation • Wax: "OZOACE0355" manufactured by Nippon Seiro Co., Ltd. • Processing aid: Lanxess "Actiplast PP" • Anti-aging agent - 1: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. • Anti-aging agent - 2: "Antage RD" manufactured by Kawaguchi Chemical Industry Co., Ltd. • Vulcanization accelerator-1: "Noxellar D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. • Vulcanization accelerator-2: "Noxellar CZ-G (CZ)" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. • Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries, Ltd.

[0052] The evaluation methods for each comparative example and example are as follows.

[0053] [Rolling resistance performance] Using a viscoelasticity testing machine manufactured by Toyo Seiki Seisakusho Co., Ltd., the loss coefficient tanδ of a rubber sample (length 20 mm x width 5 mm x thickness 2 mm) was measured at a frequency of 10 Hz, static strain 10%, dynamic strain 1%, and temperature 60°C (tensile mode). The reciprocal of the measured loss coefficient tanδ is shown as an exponent, with the values ​​for Comparative Example 1 (Table 1), Comparative Example 5 (Table 2), Comparative Example 7 (Table 3), and Comparative Example 14 (Table 4) set to 100. A larger exponent indicates a smaller loss coefficient tanδ and superior rolling resistance performance.

[0054] [Wet grip performance] Using a viscoelasticity testing machine manufactured by NETZSCH, the loss coefficient tanδ of a rubber sample (width 5 mm x thickness 2 mm) was measured at a frequency of 10 Hz, static strain of 10%, dynamic strain of 1%, temperature of 0°C, and gripping distance of 20 mm (tensile mode). In Table 1, the value for Comparative Example 1 is set to 100, in Table 2 to 100, in Table 3 to 100, in Table 3 to 100, and in Table 4 to 100. The values ​​for each comparative example and example are shown as indices. A larger value indicates a larger loss coefficient tanδ and superior wet grip performance.

[0055] [Wear resistance] In accordance with JIS K6264-2:2005, the wear loss of a rubber sample (49 mm in diameter x 5 mm in thickness) was measured using a Lambourn friction tester manufactured by Iwamoto Seisakusho Co., Ltd., under a load of 40 N, a slip ratio of 30%, and a powdering agent drop rate of 20 g / min. The reciprocal of the measured wear loss was set as an index in Table 1 for Comparative Example 1, Table 2 for Comparative Example 5, Table 3 for Comparative Example 7, and Table 4 for Comparative Example 14, with each index representing the reciprocal of the measured wear loss. A larger index indicates less wear loss and superior wear resistance.

[0056] [Overall performance] The average values ​​of the measurement results (indices) for rolling resistance performance, wet grip performance, and wear resistance performance of each comparative example and example were calculated and used as an index for the overall performance of the three performances mentioned above. A higher average value indicates better overall performance.

[0057] [First Experimental Example] Rubber compositions for Comparative Examples 1-4 and Examples 1-5 were prepared using a Banbury mixer according to the formulations (parts by mass) listed in Table 1 below. Specifically, in the first mixing stage, all additives except the vulcanization accelerator and sulfur were added to the rubber component along with a naturally derived liquid resin and sustainable oil, and kneaded (discharge temperature = 160°C). In the final mixing stage, the vulcanization accelerator and sulfur were added to the resulting mixture and kneaded (discharge temperature = 100°C) to prepare the rubber composition. Each of the obtained rubber compositions was vulcanized at 160°C for 20 minutes. The rolling resistance performance, wet grip performance, and abrasion resistance performance of each obtained vulcanized rubber sample were evaluated.

[0058] The results are shown in Table 1 below. In Table 1, only styrene-butadiene rubber was used as the rubber component, and solid resin-1 was used as the solid resin. Comparative Example 1 is a conventional compound system that incorporates aromatic oil as a softening agent. In Comparative Example 2, compared to Comparative Example 1, a portion of the aromatic oil was replaced with sustainable oil-1. Although rolling resistance performance improved, wet grip performance and wear resistance deteriorated, resulting in inferior overall performance.

[0059] In Comparative Example 3, a portion of the aromatic oil was replaced with liquid resin-1 compared to Comparative Example 1. While wet grip performance improved, rolling resistance and wear resistance deteriorated, resulting in inferior overall performance.

[0060] In Comparative Example 4, compared to Comparative Example 1, 5 parts by mass of Sustainable Oil-1 were added instead of 15 parts by mass of Aromatic Oil, and the amount of Solid Resin-1 was increased by 10 parts by mass. While wet grip performance improved, rolling resistance and wear resistance deteriorated. In particular, rolling resistance performance deteriorated significantly, resulting in inferior overall performance.

[0061] Examples 1 to 5 are examples in which a naturally derived liquid resin and sustainable oil were blended in place of aromatic oil, such that the mass ratio of the naturally derived liquid resin to the sustainable oil (hereinafter simply referred to as "mass ratio") was within the specified range. In all of these examples, the overall performance was improved compared to Comparative Examples 1 to 4.

[0062] [Table 1]

[0063] [Second Experimental Example] The rubber compositions of Comparative Examples 5 and 6 and Examples 6 and 7 were prepared according to the formulations (parts by mass) listed in Table 2 below, with the rest being the same as in Experimental Example 1. Each of the obtained rubber compositions was vulcanized under the same conditions as in Experimental Example 1. The rolling resistance performance, wet grip performance, and abrasion resistance performance of each obtained vulcanized rubber sample were evaluated.

[0064] The results are shown in Table 2 below. In Table 2, only styrene-butadiene rubber was used as the rubber component, and solid resin-2 was used as the solid resin. Comparative Example 5 is an example in which an aromatic oil was added as a softening agent. Comparative Example 6 is an example in which, compared to Comparative Example 5, 5 parts by mass of sustainable oil-2 were added instead of 15 parts by mass of aromatic oil, and the amount of solid resin-2 was increased by 10 parts by mass. Compared to Comparative Example 5, the wet grip performance was improved, and the wear resistance performance was equivalent. On the other hand, the rolling resistance performance was worse, and the overall performance was inferior.

[0065] Examples 6 and 7 are examples in which liquid resin-1 and sustainable oil-2 were used instead of aromatic oil, and the mixture was formulated so that their mass ratio was within the specified range. In all examples, the overall performance was improved compared to comparative examples 5 and 6.

[0066] [Table 2]

[0067] [Third experimental example] Rubber compositions for Comparative Examples 7-13 and Examples 8-11 were prepared according to the formulations (parts by mass) listed in Table 3 below, with the rest being the same as in Experimental Example 1. Each of the obtained rubber compositions was vulcanized under the same conditions as in Experimental Example 1. The rolling resistance performance, wet grip performance, and abrasion resistance performance of each obtained vulcanized rubber sample were evaluated.

[0068] The results are shown in Table 3 below. In Table 3, styrene-butadiene rubber and butadiene rubber were used in combination as the rubber component. Comparative Example 7 is an example in which an aromatic oil was added as a softening agent. In Comparative Example 8, the aromatic oil was replaced with Sustainable Oil-1 compared to Comparative Example 7. Although the rolling resistance performance improved, the wet grip performance and wear resistance performance deteriorated, resulting in inferior overall performance.

[0069] Comparative Example 9 is an example in which the aromatic oil was replaced with Sustainable Oil-2 compared to Comparative Example 7. Compared to Comparative Example 7, rolling resistance performance improved, but wet grip performance and wear resistance deteriorated. In particular, wear resistance deteriorated significantly, resulting in inferior overall performance.

[0070] In Comparative Example 10, the aromatic oil was replaced with liquid resin-1 compared to Comparative Example 7. While wet grip performance improved, rolling resistance and wear resistance deteriorated, resulting in inferior overall performance.

[0071] Comparative Examples 11 and 12 are examples in which sustainable oil-2 and liquid resin-1 were blended so that their mass ratio was below the lower limit. Compared to Comparative Example 7, rolling resistance performance improved, but wet grip performance and wear resistance deteriorated, resulting in inferior overall performance.

[0072] Comparative Example 13 is an example in which sustainable oil-2 and liquid resin-1 were blended in such a way that their mass ratio exceeded the upper limit. Compared to Comparative Example 7, wet grip performance improved, but rolling resistance and wear resistance deteriorated, resulting in inferior overall performance.

[0073] Examples 8 to 11 are examples in which liquid resin-1 and sustainable oil were used instead of aromatic oil, and the mixture was formulated so that the mass ratio was within the specified range. In Example 11, the same overall performance as Comparative Example 7 was maintained, and in Examples 8 to 10, the overall performance was improved compared to Comparative Examples 7 to 13.

[0074] [Table 3]

[0075] [Fourth Experimental Example] Comparative Example 14 and Example 12 rubber compositions were prepared according to the formulations (parts by mass) listed in Table 4 below, with the rest being the same as in Experimental Example 1. Each of the obtained rubber compositions was vulcanized under the same conditions as in Experimental Example 1. The rolling resistance performance, wet grip performance, and abrasion resistance performance of each obtained vulcanized rubber sample were evaluated.

[0076] The results are shown in Table 4 below. In Table 4, styrene-butadiene rubber, butadiene rubber, and natural rubber were used in combination as rubber components, and only carbon black was used as a filler. Comparative Example 14 is an example in which an aromatic oil was added as a softening agent. In contrast, Example 12 is an example in which liquid resin-1 and sustainable oil-2 were used instead of aromatic oil, and the mixture was formulated so that their mass ratio was within the specified range. In Example 12, the overall performance was improved compared to Comparative Example 14.

[0077] [Table 4]

[0078] Furthermore, the various numerical ranges described in this specification can be any combination of their upper and lower limits, and all such combinations are described herein as preferred numerical ranges. Also, the description of a numerical range as "X~Y" means X or greater and Y or less.

[0079] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their omissions, substitutions, and modifications are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

Claims

1. A rubber composition for tires comprising rubber components, naturally derived liquid resin, and sustainable oil, A rubber composition for tires, wherein the mass ratio of the naturally derived liquid resin to the sustainable oil is 1 to 4.

2. The tire rubber composition according to claim 1, wherein the sustainable oil includes a vegetable oil.

3. The tire rubber composition according to claim 1, wherein the total content of the naturally derived liquid resin and the sustainable oil per 100 parts by mass of the rubber component is 5 to 80 parts by mass.

4. A tire having a rubber portion made using the tire rubber composition described in any one of claims 1 to 3.

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