Method for manufacturing rubber compositions and vulcanized rubber products

Abstract

To provide a rubber composition with excellent overall performance in terms of ozone resistance and appearance. [Solution] The present invention relates to a rubber composition containing wax having an iso component ratio of 15% by mass or less.

Description

Technical Field

[0001] The present invention relates to a rubber composition and a method for producing a vulcanized rubber product.

Background Art

[0002] In rubber compositions used for automobile tires, wax is generally blended to prevent ozone deterioration. However, there is a problem that the appearance of the rubber surface is impaired by whitening due to excessive bloom (deposition on the rubber surface). Various techniques for preventing the deterioration of the appearance of tires, such as blending an ether-type nonionic surfactant of polyoxyethylene, have been proposed (Patent Document 1, etc.).

[0003] Particularly, in a rubber composition containing a relatively large amount of isoprene rubber, when measures such as reducing the amount of wax are taken to improve the appearance, since the ozone resistance inherent to isoprene rubber is poor, deterioration due to contact with ozone may occur and it is feared that cracks may occur. Therefore, further improvement in improving the appearance while obtaining good ozone resistance is desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above situation, and an object thereof is to provide a rubber composition excellent in the overall performance of ozone resistance and appearance.

Means for Solving the Problems

[0006] The present invention relates to a rubber composition containing a wax having an isocomponent ratio of 15% by mass or less.

Effects of the Invention

[0007] Since the rubber composition contains wax with an iso-component ratio of 15% by mass or less, the overall performance of ozone resistance and appearance can be improved.

Brief Description of the Drawings

[0008] [Figure 1] It is a cross-sectional view showing a part of a pneumatic tire. [Figure 2] It is an enlarged cross-sectional view showing the vicinity of the tread of the tire of FIG. 1.

Mode for Carrying Out the Invention

[0009] The rubber composition is characterized by containing wax with an iso-component ratio of 15% by mass or less.

[0010] The mechanism by which the above-described effects are obtained is not clear, but it is推测 as follows. Among waxes, by using wax with an iso-component ratio of 15% by mass or less, ozone resistance becomes good, and thereby appearance becomes good, and it is推测 that the overall performance of ozone resistance and appearance is improved.

[0011] <Rubber component> The rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking. Generally, a polymer with a weight average molecular weight (Mw) of 10,000 or more, and a polymer component that is not extracted by acetone corresponds to the rubber component. The above components are in a solid state at 25°C.

[0012] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, still more preferably 200,000 or more, particularly preferably 270,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, still more preferably 1,000,000 or less. When within the above range, the effect tends to be obtained more favorably.

[0013] 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.

[0014] The rubber component usable in the above rubber composition may be unmodified rubber or modified rubber. Examples of modified rubbers include rubbers having functional groups that interact with fillers such as silica. For example, end-modified rubber (end-modified rubber having the functional group at the end) is obtained by modifying at least one end of the rubber with a compound (modifier) ​​having the functional group; main-chain modified rubber having the functional group in the main chain; main-chain end-modified rubber having the functional group in both the main chain and the end (for example, main-chain end-modified rubber having the functional group in the main chain and at least one end modified with the modifier); and end-modified rubber that has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and into which hydroxyl groups or epoxy groups have been introduced.

[0015] Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0016] In the above rubber composition, examples of usable rubber components include diene-based rubbers. Examples of diene-based rubbers include isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). Other rubber components include butyl-based rubber and fluororubber. These may be used individually or in combination of two or more. Furthermore, these rubber components may be subjected to modification treatment or hydrogenation treatment, and stretched rubber, which has been stretched with oil, resin, or liquid rubber components, may also be used. In particular, from the viewpoint of obtaining better results, it is preferable to include at least one of isoprene rubber, BR, SBR, EPDM, and butyl rubber, and it is more preferable to include at least one of isoprene rubber, BR, and SBR.

[0017] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include styrene, but are not particularly limited. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0018] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0019] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0020] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl. The butadiene is 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited and includes styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of plants and animals. A typical biological conversion is fermentation by microorganisms, while chemical and / or physical conversions include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0021] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0022] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0023] pMC is the -12 ratio of the 14 C concentration of the sample to the

[0024] C concentration of the modern standard reference, and is a value used as an index indicating the biomass ratio of a compound. The meaning of this value will be described below. 23 In one mole (6.02×10 11 ) of carbon atoms, there are approximately 6.02×10 14 C, which is about one trillionth of the normal carbon atoms. 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of them to decay. Therefore, after carbon dioxide in the atmosphere and the like are taken up and fixed by plants and the like, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226, years since fixation, all of the 14 C elements contained in them at the beginning of fixation have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 C elements. Therefore, chemical substances produced from these fossil fuels as raw materials also do not contain any 14 C elements.

[0025] On the other hand, 14 C is constantly generated by nuclear reactions of cosmic rays in the atmosphere, and the balance between the decrease due to radioactive decay results in a constant amount of 14 C in the earth's atmospheric environment. Therefore, the 14 C concentration of substances derived from biomass resources circulating in the current environment is about 1×10 -12 mol% with respect to the entire C atoms as described above. Therefore, by using the difference between these values, the biomass ratio of a certain compound can be calculated.

[0026] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0027] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0028] For the reasons stated above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0029] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, common types used in the rubber industry can be used, such as SIR20, RSS#3, and TSR20. For IR, there are no particular limitations; common types used in the rubber industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. 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 types.

[0030] BR is not particularly limited, and 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. In particular, it is preferable that the BR contains high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0031] The cis amount of BR refers to the cis amount of a single type of BR, and the average cis amount if there are multiple types of BR. The average cis content of BR can be calculated using the formula {Σ(content of each BR × cis content of each BR)} / total BR content. For example, if 20% of BR has a cis content of 90% and 10% has a cis content of 40% out of 100% of rubber components, the average cis content of BR is 73.3% (=(20 × 90 + 10 × 40) / (20 + 10)).

[0032] Furthermore, both unmodified and modified BR can be used. Modified BR includes BR in which functional groups similar to those of modified rubber have been introduced. Hydrogenated butadiene polymer (hydrogenated BR) can also be used.

[0033] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0034] The SBR is not particularly limited; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. These may be used individually or in combination of two or more types.

[0035] The styrene content of SBR is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 20% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. When the content is within the above range, the effect tends to be better obtained. In this specification, the styrene content can be measured by pyrolysis gas chromatography analysis.

[0036] The styrene content of SBR refers to the styrene content of a single type of SBR if it is one type, and to the average styrene content if it is one of multiple types. The average styrene content of SBR can be calculated using the formula {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with 40% styrene content and 5% is SBR with 25% styrene content, the average styrene content of the SBR is 39.2% (=(85 × 40 + 5 × 25) / (85 + 5)).

[0037] The amount of vinyl bonded to SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more. When the amount of vinyl bonded is within the above range, preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, the effect tends to be better. In this specification, the amount of vinyl bond (amount of 1,2-bonded butadiene units) can be measured by pyrolysis gas chromatography analysis.

[0038] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is the ratio of vinyl bonds to the total mass of the butadiene portion in the SBR, with the total mass being 100 (unit: mass%). The formula is: vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. If there is only one type of SBR, it refers to the vinyl content of that SBR; if there are multiple types, it refers to the average vinyl content. The average vinyl content of SBR can be calculated using the formula: Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%]) × Vinyl content of each SBR [mass%]} / Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%])}. For example, if 100 parts by mass of rubber component, 75 parts by mass of SBR contain 40% by mass of styrene and 30% by mass of vinyl, and 25% by mass of vinyl, If 15 parts by mass of SBR have a 20% vinyl content and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [mass%] - 40 [mass%]) × 30 [mass%] + 15 × (100 [mass%] - 25 [mass%]) × 20 [mass%])} / {75 × (100 [mass%] - 40 [mass%]) + 15 × (100 [mass%] - 25 [mass%])}.

[0039] Both unmodified and modified SBR can be used. Modified SBR includes SBR with functional groups similar to those introduced in modified rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0040] 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. Alternatively, SBR synthesized by known methods can also be used.

[0041] Specific examples of the above-mentioned butyl rubber include butyl rubber; halogenated butyl rubbers such as chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), and fluorinated butyl rubber (F-IIR); and others. Commercially available butyl rubbers include Exprobutyl and chlorobutyl HT1068 manufactured by ExxonMobil. The above-mentioned butyl rubbers may be used alone or in combination of two or more types. In particular, from the viewpoint of obtaining better effects, it is preferable to include halogenated butyl rubber, and more preferably to include brominated butyl rubber.

[0042] The above-mentioned butyl rubber can be either unmodified butyl rubber or modified butyl rubber. Examples of modified butyl rubbers include modified butyl rubbers in which functional groups similar to those of the modified rubber described above have been introduced.

[0043] As the above-mentioned EPDM, known materials can be used, for example, an ethylene-propylene-diene ternary copolymer obtained by copolymerizing an ethylene-propylene copolymer with a diene component to introduce an unsaturated bond. The EPDM may be a single type or a combination of two or more types.

[0044] The diene component used in the above EPDM is not particularly limited, but typically those with 5 to 20 carbon atoms are used. Specifically, examples include cyclic dienes such as 5-ethylidene-2-norbornene (ethylidenenorbornene), 5-propyridene-5-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, and norbornadiene; and chain-like unconjugated dienes such as 1,4-pentadiene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene, 5-methyl-1,5-heptadiene, 6-methyl-1,5-heptadiene, and 6-methyl-1,7-octadiene. Among these, cyclic dienes are preferred in terms of cleanliness and resistance to compression set, and 5-ethylidene-2-norbornene is particularly preferred. These may be used individually or in combination of two or more.

[0045] The content of diene components in 100% by mass of the total raw materials constituting EPDM is preferably 6% by mass or more and 14% by mass or less. Note that EPDM may be a mixture of EPDM with different diene content, in which case the above content of diene components is the average content of diene components in all EPDM.

[0046] Furthermore, the ethylene content in 100% by mass of the total raw materials constituting EPDM is preferably 35% by mass or more and 70% by mass or less.

[0047] EPDM has a Mooney viscosity (ML). 1+4 The viscosity (at 125°C) is preferably between 5 and 100. Note that the Mooney viscosity mentioned above is the viscosity of the raw rubber measured with a Mooney viscometer.

[0048] When the above rubber composition contains isoprene-based rubber, the isoprene-based rubber content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and even more preferably 40% by mass or more, and also preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0049] When the above rubber composition contains BR, the BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0050] When the above rubber composition contains SBR, the SBR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0051] When the above rubber composition contains butyl rubber, the content of the butyl rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and also preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0052] When the above rubber component composition contains EPDM, the content of butyl rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and also preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0053] <Filler> The above rubber composition preferably contains a filler. The above-mentioned fillers are not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, as well as biochar (BIO CHAR); and poorly dispersible fillers. Among these, carbon black and silica are preferred from the viewpoint of obtaining better results.

[0054] The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Corporation. Carbon black may be used alone or in combination of two or more types.

[0055] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 5m². 2 Preferably 20m / g or more. 2 More preferably 40m 2 More preferably, the amount of N2SA is 200m 2 Preferably less than / g, 130m 2 Less than / g is more preferable, 120m 2 A value of less than / g is even more preferable. Within the above range, there is a tendency to obtain better effects. The specific surface area for nitrogen adsorption of carbon black is determined according to JIS K6217-2:2001.

[0056] In the above rubber composition, the silica that can be used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it has a high silanol group content. These silicas may be used individually or in combination of two or more types.

[0057] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0058] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0059] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0060] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0061] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m². 2 / g or more, more preferably 80m 2 / g or more, more preferably 100m 2 It is 1 / g or more. Furthermore, the upper limit of N2SA in silica is not particularly limited, but preferably 350m 2 Less than / g, more preferably 300m 2 / g or less, more preferably 250m 2 It is less than / g. Within the above range, better effects tend to be obtained. Note that the N2SA value of silica is measured by the BET method in accordance with ASTM D3037-93.

[0062] Examples of poorly dispersible fillers include microfibrillated plant fibers, short fibrous cellulose, and gel-like compounds. Among these, microfibrillated plant fibers are preferred.

[0063] As the above-mentioned microfibrillated plant fiber, cellulose microfibrils are preferred in that they provide good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include resource biomass such as fruits, grains, and root vegetables; wood, bamboo, hemp, jute, and kenaf, as well as waste biomass such as pulp, paper, cloth, agricultural residues, food waste, and sewage sludge obtained from these raw materials, unused biomass such as rice straw, wheat straw, and thinned wood, and cellulose produced by sea squirts, acetic acid bacteria, etc. One type of these microfibrillated plant fiber may be used, or two or more types may be used in combination.

[0064] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, and more typically, cellulose fibers having a microstructure with an average fiber diameter of 500 nm or less, formed by an aggregate of cellulose molecules. Typical cellulose microfibrils are formed, for example, as aggregates of cellulose fibers having the average fiber diameter described above.

[0065] In the above rubber composition, the filler content (total amount of fillers such as carbon black and silica) is preferably 5 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and 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 content is within the above range, a better effect tends to be obtained.

[0066] When the above rubber composition contains carbon black, the carbon black content is preferably 5 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 70 parts by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0067] When the above rubber composition contains silica, the silica content is preferably 5 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and also preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 70 parts by mass or less, per 100 parts by mass of the rubber component. When the silica content is within the above range, the effect tends to be better obtained.

[0068] <Silane coupling agent> 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 any known in the rubber field can be used, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products from companies such as Evonik, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0069] In the above rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, per 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0070] <wax> The above rubber composition contains wax with an iso component ratio of 15% by mass or less. The wax is capable of suppressing degradation from ozone and usually contains iso-components and normal-components, but the above rubber composition contains wax in which the ratio of the content of iso-components to the total amount of iso-components and normal-components (iso-component ratio) is 15% by mass or less.

[0071] In this specification, the iso component of a wax means a branched (having a main chain and side chains) saturated hydrocarbon, and the normal component of a wax means an unbranched (having only a main chain) saturated hydrocarbon. Furthermore, in this specification, the iso component ratio can be expressed by the following formula. Iso component ratio (mass%) = Amount of iso component / (Amount of iso component + Amount of normal component) × 100 In the above formula, the iso component amount represents the content (mass%) of the iso component in 100% by mass of wax, and the normal component amount represents the content (mass%) of the normal component in 100% by mass of wax. The above amounts of iso and normal components can be calculated using gas chromatography.

[0072] The iso component ratio is preferably 12% by mass or less, more preferably 10% by mass or less, and even more preferably 7% by mass or less. The lower limit of the iso component ratio is not particularly limited, but for example, 3% by mass or more is preferred, and 5% by mass or more is more preferred. Within this range, a better effect tends to be obtained.

[0073] The origin of the above-mentioned wax is not particularly limited as long as the iso component ratio is 15% by mass or less. Examples include petroleum-based waxes such as paraffin wax and microcrystalline wax; and synthetic waxes such as polymers of ethylene and propylene. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. They can also be synthesized by known methods. These may be used individually or in combination of two or more. Furthermore, polyethylene or the like may be added to these waxes to prevent blooming and / or blocking.

[0074] Of the above waxes, synthetic waxes produced by chemical synthesis are preferred, and synthetic waxes produced by chemical synthesis using sustainable materials such as biomass (organic resources of biological origin excluding fossil resources) as raw materials are even more preferred. Such synthetic waxes can be manufactured, for example, from substances obtained by heat treatment of biomass. Because sustainable materials such as biomass, which are abundant on Earth, are used as raw materials, it is possible to easily secure the amount of wax necessary for tire manufacturing while using sustainable materials, enabling mass production and reducing costs. Furthermore, it is possible to reduce variations in quality. Examples of the above-mentioned substances include biogas (sustainable methane, carbon monoxide, hydrogen, etc.), alcohols (methanol, ethanol, butanol, etc.), fatty acids, glycerin fatty acid esters (oils and fats), and polyglycols (polyethylene glycol, etc.). Among these, biogas is preferred from the viewpoint of using sustainable materials, and sustainable methane is more preferred. In this specification, chemical synthesis refers to the production of a target compound using chemical reactions (including microbial and enzymatic reactions).

[0075] The method for producing the above-mentioned synthetic wax is not particularly limited. For example, the Fischer-Tropsch process (as described in Japanese Patent Publication No. 2008-56817, Japanese Patent Publication No. 2008-231270, etc.) or methods utilizing enzymes or microorganisms (as described in Japanese Patent Publication No. 2006-211924, Japanese Patent Publication No. 63-28396, etc.) can be used. Among these, the Fischer-Tropsch process is preferred from the viewpoint of obtaining better results.

[0076] As described above, the wax is preferably a wax obtained by Fischer-Tropsch synthesis (also known as FT wax). Furthermore, in recent years, there has been a demand to improve the sustainable ratio of tire materials in consideration of environmental impact, and it is desirable to use sustainable materials as raw materials for wax as well. From this viewpoint, it is preferable that the raw material for the Fischer-Tropsch synthesis is sustainable methane or carbon monoxide converted from carbon dioxide. This makes it possible to obtain a wax derived from sustainable materials.

[0077] The source of the sustainable methane mentioned above is not particularly limited, but from the viewpoint of using more sustainable materials, it is preferable that it be methane produced from human waste or industrial wastewater, or methane synthesized by methanation.

[0078] The amount of wax with an iso component ratio of 15% by mass or less is preferably 0.5 parts by mass or more, more preferably 0.9 parts by mass or more, even more preferably 1.2 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of rubber component, and also preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less. When the amount is within the above range, the effect tends to be better obtained.

[0079] Furthermore, the content of the wax obtained by the Fischer-Tropsch synthesis described above is preferably 0.5 parts by mass or more, more preferably 0.9 parts by mass or more, even more preferably 1.2 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0080] The above rubber composition preferably contains plant-derived wax and / or hydrolysates of plant-derived wax. This tends to further suppress whitening and result in a better effect. The plant-derived waxes mentioned above are not particularly limited and include, for example, carnauba wax, candelilla wax, wood wax, sunflower wax, and rice wax. Among these, rice wax is preferred from the viewpoint of obtaining better effects. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. They can also be extracted from plants by known methods. These may be used individually or in combination of two or more. In this specification, the above-mentioned plant-derived waxes and hydrolyzates of plant-derived waxes are not included in waxes in which the above-mentioned iso-component ratio is 15% by mass or less.

[0081] Examples of hydrolyzed plant-derived waxes include those obtained by hydrolyzing part or all of the plant-derived wax by any method. Any generally known method can be used to hydrolyze the plant-derived wax. The hydrolyzed product thus obtained usually contains components other than linear monohydric primary alcohols, such as alkanes, alkenes, alkynes, carboxylic acids, ketones, aldehydes, primary alcohols that are not linear and / or contain unsaturated bonds, secondary alcohols, tertiary alcohols, dihydric or higher polyhydric alcohols, resins, wax esters, etc. However, there is no need to actively remove them, and in fact, higher fatty acids contained in the hydrolyzed product function as vulcanization aids in rubber compositions, so there is little need to remove them. Of course, any component can be removed using any method. To give a specific example, a method is known in which the fatty acids contained in the hydrolyzed product are esterified with a lower alcohol, and then the difference in solubility of the higher alcohol and the ester in a low-polarity solvent is used to remove the higher fatty acid ester and concentrate the higher alcohol (see Japanese Patent Publication No. 6-212187).

[0082] When hydrolysate of rice wax is used as the hydrolysate of the above-mentioned plant-derived wax, the hydrolysate contains higher alcohols, which tends to result in a better effect.

[0083] When the above rubber composition contains the above plant-derived wax and / or hydrolysates of plant-derived wax, the total content of the plant-derived wax and hydrolysates of plant-derived wax is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.6 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0084] When the above rubber composition contains the above-mentioned plant-derived wax and / or hydrolysate of plant-derived wax, the ratio (A / B) of the content A (parts by mass) of wax with an iso component ratio of 15% by mass or less per 100 parts by mass of rubber component to the total content B (parts by mass) of the plant-derived wax and hydrolysate of plant-derived wax per 100 parts by mass of rubber component is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more. Furthermore, it is preferably 9 or less, more preferably 8 or less, and still more preferably 7 or less. When it is within the above range, a better effect tends to be obtained.

[0085] The above rubber composition may also contain waxes other than waxes with an iso component ratio of 15% by mass or less, plant-derived waxes, and hydrolyzed plant-derived waxes.

[0086] <Surfactants> The above rubber composition may contain a surfactant. Since the above rubber composition contains wax with an iso component ratio of 15% by mass or less, it is presumed that in formulations containing surfactants, the bloom rate of the wax is suppressed, and the effect of suppressing whiteness is enhanced.

[0087] In the above rubber composition, the surfactant content per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, and also preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. When the content is within the above range, a good appearance tends to be obtained.

[0088] The surfactants mentioned above are not particularly limited and include known anionic surfactants such as polyoxyethylene alkyl ether sulfate salts, nonionic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are preferred.

[0089] The above nonionic surfactants are not particularly limited and include, for example, nonionic surfactants represented by the following formula (1) and / or formula (2); Pluronic® type nonionic surfactants; sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, and polyoxyethylene sorbitan tripalmitate; and polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene 2-ethylhexyl ether, polyoxyethylene oleyl ether, ethylene glycol dibutyl ether, ethylene glycol dilauryl ether, ethylene glycol di-2-ethylhexyl ether, and ethylene glycol dioleyl ether. These nonionic surfactants may be used alone or in combination of two or more. Among these, Pluronic type nonionic surfactants are more preferred. [ka] (In formula (1), R 1 (where 'd' represents a hydrocarbon group with 6 to 26 carbon atoms, and 'd' represents an integer.) [ka] (In formula (2), R 2 and R 3 (where e represents an integer.)

[0090] Examples of nonionic surfactants represented by the above formula (1) include ethylene glycol monooleate, ethylene glycol monopalmiate, ethylene glycol monopalmitate, ethylene glycol monopacenate, ethylene glycol monolinoleate, ethylene glycol monolinolenate, ethylene glycol monoarachidonate, ethylene glycol monostearate, ethylene glycol monocetylate, and ethylene glycol monolaurate.

[0091] Examples of nonionic surfactants represented by the above formula (2) include ethylene glycol dioleate, ethylene glycol dipalmiate, ethylene glycol dipalmitate, ethylene glycol dipacenate, ethylene glycol dilinoleate, ethylene glycol dilinolenate, ethylene glycol diarachidonate, ethylene glycol distearate, ethylene glycol dicetylate, and ethylene glycol dilaurate.

[0092] The above-mentioned pluronic-type nonionic surfactant is also called polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxypropylene block polymer, or polypropylene glycol ethylene oxide adduct, and is generally a nonionic surfactant represented by the following formula (I). As shown in the following formula (I), the pluronic-type nonionic surfactant has hydrophilic groups composed of ethylene oxide structures on both sides, and a hydrophobic group composed of a propylene oxide structure sandwiched between these hydrophilic groups. [ka] (In equation (I), a, b, and c represent integers.)

[0093] The degree of polymerization of the polypropylene oxide block of the above-mentioned Pluronic-type nonionic surfactant (b in formula (I) above) and the amount of polyethylene oxide added (a + c in formula (I) above) are not particularly limited and can be appropriately selected according to the usage conditions and purpose. The higher the proportion of polypropylene oxide block, the higher the affinity with rubber and the slower the rate of migration to the rubber surface tends to be. In particular, the degree of polymerization of the polypropylene oxide block (b in formula (I) above) is preferably 100 or less, more preferably 10 to 70, and even more preferably 10 to 60. Similarly, the amount of polyethylene oxide added (a + c in formula (I) above) is preferably 100 or less, more preferably 3 to 65, and even more preferably 5 to 55.

[0094] Examples of the above-mentioned Pluronic-type nonionic surfactants include the Pluronic series from BASF Japan Ltd., the Newpol PE series from Sanyo Chemical Industries, Ltd., the Adeka Pluronic L or F series from Asahi Denka Kogyo Co., Ltd., the Epan series from Daiichi Kogyo Seiyaku Co., Ltd., and the Pronon series or Unilube from NOF Corporation. These may be used individually or in combination of two or more.

[0095] <Plasticizer> The above rubber composition may contain a plasticizer. In this specification, "plasticizer" refers to a material that imparts plasticity to rubber components, and is a concept that includes both liquid plasticizers at 25°C and solid plasticizers at 25°C. Examples of plasticizers include resin components, oils, liquid polymers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. These plasticizers may be used individually or in combination of two or more types.

[0096] Examples of plasticizers that can be used in the above rubber composition include oils, liquid polymers, and resins. These may be used individually or in combination of two or more.

[0097] Examples of oils include mineral oil, vegetable oil, and animal oil. From a life cycle assessment perspective, waste oil used in rubber mixers and engines, or refined waste cooking oil used in restaurants, may also be used.

[0098] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0099] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils obtained by refining the above oils (such as salad oil), transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. These vegetable oils may be used individually or in combination of two or more types.

[0100] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0101] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0102] The aforementioned fatty acids are not particularly limited and may be either unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0103] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0104] As for the oil, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0105] Examples of the above-mentioned liquid polymers include liquid diene polymers (liquid rubber) and liquid farnesene polymers at 25°C. Examples of liquid rubbers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), and liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer). These polymers may have polar groups modified at the ends or main chain. Hydrogenated versions of these polymers can also be used.

[0106] The above liquid diene polymer has a weight-average molecular weight (Mw) on a polystyrene basis, measured by gel permeation chromatography (GPC), of 1.0 × 10⁻⁶. 3 ~5.0×10 4 Preferably, 3.0 × 10 3 ~1.5×10 4 It is more preferable that this is the case. Furthermore, the lower or upper limit of Mw for the liquid diene polymer may be 4500 or 8500. In this specification, the Mw of liquid diene polymers is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0107] Examples of liquid diene polymers that can be used include products from companies such as Sartomer and Kuraray.

[0108] The above-mentioned resin can be any resin commonly used in tire compounding, and may be either liquid or solid at 25°C. Examples include aromatic vinyl polymers, coumarone indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins. The resin may also be a hydrogenated resin. These may be used individually or in combination of two or more. The resin itself may also be a copolymer of monomer components of multiple origins. Among these, aromatic vinyl polymers, petroleum resins, terpene resins, and their hydrogenated resins are particularly desirable.

[0109] When using a resin that is solid at 25°C, the softening point of the above-mentioned resin is preferably 50°C or higher, more preferably 55°C or higher, even more preferably 60°C or higher, and particularly preferably 85°C or higher. Furthermore, it is preferably 160°C or lower, more preferably 150°C or lower, even more preferably 140°C or lower, and particularly preferably 100°C or lower. Within the above range, the effect tends to be better obtained. When the resin is liquid at 25°C, the softening point is preferably 20°C or lower, preferably 10°C or lower, and preferably 0°C or lower. In the case of hydrogenated resins, it is desirable that the softening point be the same as described above. The softening point of the above resin is determined by measuring the softening point specified in JIS K6220-1:2001 using a ring-type softening point measuring device, and the temperature at which the sphere descends is the softening point.

[0110] The above-mentioned aromatic vinyl polymer is a polymer containing aromatic vinyl monomers as constituent units. Examples include resins obtained by polymerizing α-methylstyrene and / or styrene, specifically, homopolymers of styrene (styrene resin), homopolymers of α-methylstyrene (α-methylstyrene resin), copolymers of α-methylstyrene and styrene, copolymers of styrene and other monomers.

[0111] The above-mentioned coumarone-indene resin is a resin that contains coumarone and indene as the main monomer components that constitute the resin's backbone (main chain). Other monomer components that may be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0112] The coumarone resin described above is a resin that contains coumarone as the main monomer component that constitutes the resin's backbone (main chain).

[0113] The above-mentioned indene resin is a resin that contains indene as the main monomer component that constitutes the resin's backbone (main chain).

[0114] As the phenolic resin mentioned above, known polymers such as those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst can be used. Among these, those obtained by reaction with an acid catalyst (such as novolac-type phenolic resins) are preferred.

[0115] Examples of the rosin resins mentioned above include natural rosin, polymerized rosin, modified rosin, their ester compounds, and rosin-based resins represented by their hydrogenated products.

[0116] Examples of the above petroleum resins include C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, C9 / DCPD resins, and hydrogenated versions thereof. Among these, DCPD resins, hydrogenated DCPD resins, C9 / DCPD resins, and C9 / hydrogenated DCPD resins are preferred.

[0117] The above-mentioned terpene resins are polymers that contain terpenes as constituent units. Examples include polyterpene resins obtained by polymerizing terpene compounds, and aromatically modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. As aromatically modified terpene resins, terpene-phenol resins made from terpene compounds and phenolic compounds, terpene-styrene resins made from terpene compounds and styrene compounds, and terpene-phenol-styrene resins made from terpene compounds, phenolic compounds, and styrene compounds can also be used. Examples of terpene compounds include α-pinene and β-pinene, examples of phenolic compounds include phenol and bisphenol A, and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among these, aromatically modified terpene resins are preferred.

[0118] The above-mentioned acrylic resin is a polymer containing acrylic monomers as constituent units. Examples include styrene-acrylic resins such as styrene-acrylic resin, which have carboxyl groups and are obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component. Among these, solvent-free carboxyl group-containing styrene-acrylic resins can be suitably used.

[0119] 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, ExxonMobil, Kraton, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., and others.

[0120] From a sustainability perspective, it is desirable to use plant-derived plasticizers such as the aforementioned plant-derived oils and farnesene polymers as plasticizers.

[0121] Farnesene polymers are polymers obtained by polymerizing farnesene and have constituent units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene, which has the following structure, is preferred. [ka]

[0122] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer). These may be used individually or in combination of two or more. Among these, the farnesene-vinyl monomer copolymer is preferred.

[0123] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, as well as conjugated diene compounds such as butadiene and isoprene. These may be used individually or in combination of two or more. Among these, butadiene is preferred. In other words, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred as the farnesene-vinyl monomer copolymer.

[0124] In farnesene-vinyl monomer copolymers, the mass-based copolymerization ratio (farnesene / vinyl monomer) of farnesene to vinyl monomer is preferably 40 / 60 to 90 / 10.

[0125] Farnesene polymers with a weight-average molecular weight (Mw) of 3,000 to 300,000 are preferably used. The Mw of the farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and also preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. Within the above range, the effect tends to be more favorably obtained.

[0126] The farnesene polymer may be in either a liquid or solid state at 25°C. However, a liquid farnesene polymer at 25°C is preferred.

[0127] If the above rubber composition contains a plasticizer, the plasticizer content (total amount of plasticizer) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. Furthermore, the plasticizer content includes the amount of oil and resin contained in oil-extracted rubber and resin-extracted rubber.

[0128] When the above rubber composition contains a solid plasticizer that is solid at 25°C, the content of the solid resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and also preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. Furthermore, the amount of solid plasticizer included in the resin-stretched rubber also includes the amount of resin contained in the resin-stretched rubber.

[0129] When the above rubber composition contains the above resin in a solid state at 25°C, the resin content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and also preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, a better effect tends to be obtained. Furthermore, the resin content includes the amount of resin contained in the resin-stretched rubber.

[0130] When the above rubber composition contains a liquid plasticizer that is in a liquid state at 25°C, the content of the liquid plasticizer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and also preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained. Furthermore, the liquid plasticizer content includes the amount of oil contained in the oil-stretched rubber and the amount of liquid resin in the resin-stretched rubber that has been stretched with liquid resin.

[0131] When the above rubber composition contains oil in a liquid state at 25°C, the amount of oil is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and also preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component. When the amount is within the above range, a better effect tends to be obtained. Furthermore, the oil content includes the amount of oil contained in the oil-applied rubber.

[0132] <Other ingredients> The above rubber composition may further contain vulcanized rubber particles. Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used individually or in combination of two or more types.

[0133] The vulcanized rubber particles are not particularly limited and may be either unmodified or modified vulcanized rubber particles.

[0134] Commercially available vulcanized rubber particles can be used, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., and others.

[0135] In the above rubber composition, the content of vulcanized rubber particles is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained.

[0136] The above rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

[0137] While not particularly limited, 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 (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0138] In the above rubber composition, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, per 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less.

[0139] The above rubber composition preferably contains stearic acid. In the above rubber composition, the stearic acid content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0140] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0141] The above rubber composition preferably contains zinc oxide. In the above rubber composition, the zinc oxide content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 5.0 parts by mass or less, and more preferably 3.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0142] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd. You may use one or more types, or even two or more types in combination.

[0143] The above rubber composition may also contain short fibers. The content of the short fibers is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by weight of the rubber component. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less.

[0144] Examples of the short fibers mentioned above include non-metallic inorganic short fibers such as glass fiber and carbon fiber, and non-metallic organic short fibers such as cellulose fiber, rayon fiber, acrylic fiber, polyester fiber, nylon fiber, aromatic polyamide fiber, urethane fiber, and aramid fiber.

[0145] The above rubber composition may contain processing aids. The content of the above processing aid is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component.

[0146] Examples of the processing aids mentioned above include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These may be used individually or in combination of two or more. In particular, it is preferable that at least one is selected from the group consisting of fatty acid metal salts, amide esters, and mixtures of fatty acid metal salts and amide esters or fatty acid amides, with fatty acid metal salts being more preferable.

[0147] The fatty acids constituting the above fatty acid metal salts are not particularly limited, but include saturated or unsaturated fatty acids (preferably saturated or unsaturated fatty acids having 6 to 28 carbon atoms (more preferably 10 to 25 carbon atoms, and even more preferably 14 to 20 carbon atoms)). Examples include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These can be used individually or in combination of two or more. Among these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

[0148] Examples of metals that make up the above fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, and molybdenum. These may be used individually or in combination of two or more. Among these, zinc and calcium are preferred, and zinc is more preferred.

[0149] The above-mentioned fatty acid amides may be either saturated or unsaturated fatty acid amides. These may be used individually or in combination of two or more. Examples of saturated fatty acid amides include N-(1-oxooctadecyl)sarcosinamide, stearic acid amide, and behenic acid amide. Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0150] Examples of the above-mentioned amide esters include fatty acid amide esters, which are composed of the above-mentioned saturated or unsaturated fatty acids. These may be used individually or in combination of two or more types.

[0151] Examples of processing aids that can be used include products from companies such as Rhein Chemie and Structol. Specifically, these include EF44 (saturated fatty acid zinc salt) from Structol, Aflux16 (a mixture of fatty acid calcium salt and amide ester) from Rhein Chemie, and WB16 (a mixture of fatty acid calcium and fatty acid amide) from Structol.

[0152] The above rubber composition preferably contains sulfur. In the above rubber composition, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 3.5 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.5 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0153] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0154] The above rubber composition preferably contains a vulcanization accelerator. In the above rubber composition, there are no particular restrictions on the content of the vulcanization accelerator, and it can be freely determined according to the desired vulcanization rate and crosslinking density. However, it is preferably 0.5 parts by mass or more, more preferably 1.3 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, and more preferably 6.0 parts by mass.

[0155] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiram-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-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. Commercially available products from companies such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. can be used. These may be used individually or in combination of two or more. Among these, sulfenamide, guanidine, and benzothiazole vulcanization accelerators are preferred.

[0156] In addition to the above components, the above rubber composition may also contain other compounding agents commonly used in the tire industry, such as mold release agents.

[0157] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the above formulations from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0158] The above rubber composition can be manufactured, for example, by kneading each of the above components using a rubber kneading device such as an open roll or Banbury mixer, and then vulcanizing them.

[0159] Regarding the mixing conditions, in the base mixing step in which additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator are mixed, the mixing temperature is preferably 100°C or higher, more preferably 120°C or higher, and also preferably 180°C or lower, more preferably 170°C or lower. In the finish mixing step in which the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is preferably 80°C or higher, also preferably 120°C or lower, more preferably 110°C or lower. 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 preferably 140°C or higher, more preferably 150°C or higher, also preferably 190°C or lower, more preferably 185°C or lower.

[0160] From the above, a method for producing a vulcanized rubber product (preferably a tire) that includes a synthesis step of producing wax by Fischer-Tropsch synthesis, a kneading step of kneading the wax obtained in the synthesis step with a rubber component to produce a rubber composition, and a vulcanization step of vulcanizing the rubber composition obtained in the kneading step is also one of the preferred embodiments.

[0161] The above rubber composition is preferably a tire rubber composition, as it can be suitably used in various tire components, for example. The tire components made of the above rubber composition are not particularly limited and include any tire components such as the tread (cap tread, base tread, under tread, etc.), sidewall, wing, bead apex, clinch (clinch apex), chafer (rubber chafer, etc.), inner liner, breaker topping, pry topping, etc. Among these, it is particularly suitable for use in the tread, sidewall, wing, clinch, chafer, etc., from the viewpoint of obtaining better results.

[0162] A tire comprising tire components made of the above-mentioned rubber composition is manufactured using the above-mentioned rubber composition by conventional methods. That is, a rubber composition, which may contain various additives as needed, can be extruded in the unvulcanized stage to match the shape of various tire components, molded in a conventional manner 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.

[0163] The above-mentioned tires are not particularly limited and include, for example, pneumatic tires, solid tires, and airless tires. Among these, pneumatic tires are preferred.

[0164] The above tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, and more.

[0165] In the above-mentioned tire, the thickness T of the tire components can be appropriately selected depending on the specific components such as the tread and sidewall, for example, it can be adjusted to be between 0.5 mm and 20 mm.

[0166] In the above-mentioned tire, the groove depth D of the circumferential grooves formed in the tread can be set as appropriate, but is preferably 0.5 mm or more, more preferably 2.0 mm or more, even more preferably 4.0 mm or more, and also preferably 15.0 mm or less, more preferably 12.0 mm or less, and even more preferably 9.0 mm or less. When the groove depth is within the above range, a better effect tends to be obtained.

[0167] In this specification, dimensions such as thickness are values ​​measured under normal conditions. "Normal conditions" refers to a state in which the tire is mounted on a normal rim, filled to the normal internal pressure, and under no load. Here, "normal rim" refers to the rim specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standards, it refers to the rim with the smallest diameter and the narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage from between the rim and tire. Furthermore, "standard internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, it refers to the "maximum air pressure" for JATMA, "INFLATION PRESSURE" for ETRTO, and the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA. Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standards, it refers to the standard internal pressure (but at least 250 kPa) of another tire size (specified in the standards) that uses the standard rim as the standard rim. If multiple standard internal pressures of 250 kPa or higher are listed, refer to the lowest value among them.

[0168] In the above-mentioned tire, the tread land ratio is preferably 30% or more, more preferably 40% or more, more preferably 50% or more, and even more preferably 55% or more, from the viewpoint of dry grip performance. The upper limit is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less, from the viewpoint of wet grip performance.

[0169] In this specification, if the tire is a pneumatic tire, the land ratio is calculated from the contact patch shape under normal rim, normal internal pressure, and normal load conditions. In the case of non-pneumatic tires, it can be measured similarly without requiring normal internal pressure. Here, "normal load" refers to the load specified for each tire in the standards system, including the standard on which the tire is based. For JATMA, it refers to the maximum load capacity; for ETRTO, it refers to "LOAD CAPACITY"; and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with the "normal rim" and "normal internal pressure" mentioned above, refer to JATMA, ETRTO, and TRA in that order and follow their respective standards. For tires not specified in the standards, the normal load W is calculated as follows: L We seek. V = {(Dt / 2)} 2 -(Dt / 2-Ht) 2} × π × Wt W L = 0.000011 × V + 175 W L :Normal load (kg) V: Virtual volume of the tire (mm) 3 ) Dt: Tire outer diameter (mm) Ht: Tire section height (mm) Wt: Tire section width (mm)

[0170] The tire's "section width Wt (mm)" is the maximum width between the outer surfaces of the sidewalls in a normal state, excluding any patterns or letters on the tire's sidewall.

[0171] The "outer diameter Dt (mm)" of a tire refers to the outer diameter of the tire in its normal state.

[0172] The "section height Ht (mm)" of a tire refers to the height in the radial direction of the tire's radial cross-section. When the tire's rim diameter is R (mm), it corresponds to half the difference between the tire's outer diameter Dt and its rim diameter R. In other words, the section height Ht can be calculated using (Dt-R) / 2.

[0173] The following diagram illustrates an example of the above-mentioned tire, but it is not limited to this form.

[0174] In Figure 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the plane of the paper is the circumferential direction of the tire 2. The tire 2 is symmetrical. The tread 4 comprises a cap layer 30 and a base layer 28. In the tire 2 of Figure 1, it is desirable that the cap layer 30 is made of the above-mentioned rubber composition. That is, it is desirable that the cap layer 30 is made of a rubber composition containing wax in which the above-mentioned iso component ratio is 15% by mass or less.

[0175] Although Figure 1 shows an example of a two-layer tread consisting of a cap layer 30 and a base layer 28, a single-layer tread or a tread with three or more layers may also be used.

[0176] The radially outer portion of the sidewall 6 is joined to the tread 4. The radially inner portion of the sidewall 6 is joined to the clinch 10. This sidewall 6 can prevent damage to the carcass 14.

[0177] Each wing 8 in Figure 1 is located between the tread 4 and the sidewall 6. The wing 8 is joined to both the tread 4 and the sidewall 6, respectively.

[0178] Each clinch 10 is located approximately radially inward of the sidewall 6 and has at least one portion that contacts the rim.

[0179] The carcass 14 is provided with a carcass ply 36. In this tire 2, the carcass 14 consists of one carcass ply 36, but it may be composed of two or more.

[0180] In this tire 2, the carcass ply 36 spans between the bead cores 32 on both sides and runs along the tread 4 and sidewall 6. The carcass ply 36 is folded back axially from the inside to the outside around each bead core 32. This folding gives the carcass ply 36 a main portion 36a and a pair of folded portions 36b. In other words, the carcass ply 36 comprises a main portion 36a and a pair of folded portions 36b.

[0181] Each bead core 32 is provided with a bead apex 34 extending radially outward from the bead core 32. The bead core 32 is preferably ring-shaped and contains a wound, non-stretchable wire. The bead apex 34 tapers radially outward.

[0182] Although not shown in the diagram, the carcass ply 36 preferably consists of a number of parallel cords and a topping rubber. The absolute value of the angle that each cord makes with respect to the equatorial plane CL is preferably between 75° and 90°. In other words, it is preferable that the carcass 14 has a radial structure.

[0183] The belt layer 16 in Figure 1 is located radially inward of the tread 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. In the tire 2 of Figure 1, the belt layer 16 consists of an inner layer 38 and an outer layer 40. As is clear from Figure 1, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40 in the axial direction. In this tire 2, the axial width of the belt layer 16 is preferably 0.6 times or more, and preferably 0.9 times or less, the cross-sectional width of the tire 2.

[0184] Preferably, each of the inner layer 38 and the outer layer 40 consists of a number of parallel single-strand steel cords (steel monofilaments) and a topping rubber (coating rubber). In other words, the belt layer 16 contains a number of parallel steel monofilaments.

[0185] In Figure 1, band 18 is located radially outside the belt layer 16. In the axial direction, band 18 has a width equal to the width of the belt layer 16. Band 18 may have a width greater than the width of the belt layer 16.

[0186] Although not shown in the diagram, the band 18 preferably consists of a cord and a topping rubber. The cord is wound in a spiral shape. This band 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is preferably 5° or less, and more preferably 2° or less. Since the belt layer 16 is restrained by this cord, lifting of the belt layer 16 is suppressed.

[0187] The belt layer 16 and band 18 in Figure 1 constitute the reinforcing layer. The reinforcing layer may also be composed of only the belt layer 16.

[0188] Figure 2 is a magnified view of the area around tread 4 in Figure 1. The tire in Figure 2 is a tire 2 having grooves 26 on the tire's equatorial plane (on the CL).

[0189] The inner liner 20 is located inside the carcass 14. The inner liner 20 is bonded to the inner surface of the carcass 14.

[0190] The inner liner 20 is made of the rubber composition for the inner liner, which includes butyl rubber and microfibrillated plant fibers. The inner liner 20 maintains the internal pressure of the tire 2.

[0191] Each chafer 22 is located near the bead 12. In this embodiment, it is preferable that the chafer 22 consists of cloth and rubber impregnated into the cloth. The chafer 22 may be integrated with the clinch 10.

[0192] In tire 2, at least one of the tire components, including the cap layer 30 and / or base layer 28, sidewall 6, wing 8, clinch 10, and chafer 22, is made of the above-mentioned rubber composition.

[0193] In this tire 2, the tread 4 is provided with main grooves 42 as grooves 26. As shown in Figure 1, this tread 4 has multiple main grooves 42, specifically three. These main grooves 42 are spaced apart in the axial direction. The three main grooves 42 in this tread 4 form four ribs 44 that extend in the circumferential direction. In other words, the space between the ribs 44 is the main groove 42.

[0194] Each main groove 42 extends in the circumferential direction. The main grooves 42 are continuous and uninterrupted in the circumferential direction. The main grooves 42 promote the drainage of water present between the road surface and the tire 2, for example, in rainy weather. Therefore, even when the road surface is wet, the tire 2 can make sufficient contact with the road surface. Figure 2D shows the groove depth of the circumferential main grooves 42 formed in the tread 4. [Examples]

[0195] The following examples (implementations) are considered preferable for implementation, but the scope of this disclosure is not limited to these examples.

[0196] The various chemicals used in the examples and comparative examples are described below. NR:TSR20 BR: BR150B manufactured by Ube Industries, Ltd. (Cis content: 97% by mass) Carbon Black: N550 (N2SA: 41m) manufactured by Cabot Japan Co., Ltd. 2 / g) Wax 1: Commercial wax (petroleum-based wax, iso-component ratio: 27% by mass) Wax 2: Prototype Wax 1 (FT wax, iso component ratio: 7% by mass) Wax 3: Prototype Wax 2 (FT wax using sustainable methane as a raw material, iso component ratio: 7% by mass) Rice wax: Rice wax Hydrolyzed product: Prototype wax 3 (hydrolyzed rice wax) Anti-aging agent 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent 2: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Oil: VIVATEC500 (aromatherapy process oil) by H&R. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar CZ-G (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0197] To calculate the iso-component ratio of the wax, the amounts of iso-components and normal-components are measured by the following method. A capillary GC (GC2010, Shimadzu Corporation) was used as the measuring instrument, and a capillary column (MXT-1, RESTEK) was used as the column. Measurements were performed under the following conditions: helium as the carrier gas, flow rate of 40 ml / min, column temperature of 160-390°C, heating rate of 8°C / min, and FID detector.

[0198] (Manufacturing Example 1: Manufacturing of Prototype Wax 1) Carbon monoxide and hydrogen are supplied to a Fischer-Tropsch reactor packed with a cobalt catalyst held on a silica support, and the reaction is carried out. After cooling, the wax is separated by distillation. The obtained wax is further divided into smaller pieces by any method, and the divided wax is mixed in any proportion to obtain prototype wax 1 (FT wax). The iso component ratio of prototype wax 1 is 7% by mass.

[0199] (Manufacturing Example 2: Manufacturing of Prototype Wax 2) Biogas containing carbon monoxide and hydrogen (obtained from livestock manure compost) is supplied to a Fischer-Tropsch reactor packed with a cobalt catalyst held on a silica support, and the reaction is carried out. After cooling, the wax is separated by distillation. The obtained wax is further divided into smaller pieces by any method, and the divided wax is mixed in any proportion to obtain prototype wax 2 (FT wax using sustainable methane as a raw material). The iso-component ratio of prototype wax 2 is 7% by mass.

[0200] (Manufacturing Example 3: Manufacturing of Prototype Wax 3) Rice wax is subjected to hydrolysis to obtain prototype wax 3 (hydrolyzed rice wax).

[0201] (Examples and Comparative Examples) According to the formulation shown in Table 1, the chemicals other than sulfur and vulcanization accelerator were mixed for 4 minutes at 160°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture. Sulfur and a vulcanization accelerator are added to the mixture, and the mixture is kneaded using an open roll at 80°C for 4 minutes to obtain an unvulcanized rubber composition. The unvulcanized rubber composition is molded into the shape of a sidewall, bonded together with other tire components on a tire molding machine to form an unvulcanized tire, and vulcanized at 170°C for 10 minutes to produce a test tire (size 205 / 55R17, passenger car tire).

[0202] Table 1 shows the results calculated based on the evaluation method described below, assuming test tires obtained from compositions with varying formulations according to Table 1. The reference comparison examples are as follows: Table 1: Comparative Example 1

[0203] <Ozone resistance evaluation> In accordance with JIS K 6259 "Vulcanized rubber and thermoplastic rubber - Method for determining ozone resistance," a test piece of a specified size (a strip-shaped test piece with a width of 5 mm and a length of 20 mm) is cut from the cap tread of a test tire, and a dynamic ozone degradation test is performed. Under the conditions of a reciprocating motion frequency of 0.5 ± 0.025 Hz, an ozone concentration of 50 ± 5 pphm, a test temperature of 40°C, and a tensile strain of 20 ± 2%, ozone resistance is evaluated by observing the state of cracks (presence or absence of crack formation) after 48 hours of testing. The evaluation is expressed as an index with the standard comparative example set to 100 (ozone resistance index). A higher index indicates fewer cracks, smaller crack size, and superior ozone resistance (ozone crack performance). A higher index value indicates better ozone resistance.

[0204] <Degree of whitening> After storing the test tires in an indoor warehouse protected from rain for 90 days, a portion of the sidewall is scraped off with a spatula, and a photograph is taken. The degree of whiteness is evaluated from the difference in brightness between the images with and without the scraping. The evaluation is expressed as an index, with the reference comparison set at 100 (whitening index). A higher index indicates less whitening, a darker, glossier appearance, and superior whitening performance (whitening is suppressed, i.e., superior appearance). A higher index indicates better appearance.

[0205] [Table 1]

[0206] The present invention (1) is a rubber composition containing a wax having an iso component ratio of 15% by mass or less.

[0207] The present invention (2) is the rubber composition according to the present invention (1), wherein the wax is a wax obtained by Fischer-Tropsch synthesis.

[0208] The present invention (3) is a rubber composition containing wax obtained by Fischer-Tropsch synthesis.

[0209] The present invention (4) is a rubber composition according to the present invention (2) or (3), wherein the raw material for the Fischer-Tropsch synthesis is sustainable methane or carbon monoxide converted from carbon dioxide.

[0210] The present invention (5) is a rubber composition according to the present invention (4), wherein the sustainable methane is methane produced from human waste or industrial wastewater, or methane synthesized by methanation.

[0211] The present invention (6) is a rubber composition comprising any combination of any of the present inventions (1) to (5) and a plant-derived wax and / or a hydrolyzed product of a plant-derived wax.

[0212] The present invention (7) is the rubber composition according to the present invention (6), wherein the plant-derived wax is rice wax.

[0213] The present invention (8) is a rubber composition according to the present invention (6) or (7), wherein the ratio (A / B) of the content A (parts by mass) of wax, in which the ratio of the iso component to 100 parts by mass of rubber is 15% by mass or less, to the total content B (parts by mass) of the plant-derived wax and hydrolysate of plant-derived wax per 100 parts by mass of rubber component is 2 or more and 9 or less.

[0214] The present invention (9) is a rubber composition in any combination with any of the present inventions (1) to (8), which are rubber compositions for tires.

[0215] The present invention (10) is a method for producing a vulcanized rubber product, comprising a synthesis step of producing wax by Fischer-Tropsch synthesis, a kneading step of kneading the wax obtained in the synthesis step with a rubber component to produce a rubber composition, and a vulcanization step of vulcanizing the rubber composition obtained in the kneading step.

[0216] The present invention (11) is a manufacturing method according to the present invention (10), wherein the vulcanized rubber product is a tire. [Explanation of Symbols]

[0217] 2 tires 4 tread 6 Sidewall 8 Wing 10. Clinch 12 beads 14 Carcass 16 Belt Layer 18 bands 20 Inner Liner 22 Chafer 24 Tread surface 26 Groove 28 Base Layer 30 cap layers 32 Bead Core 34 Bead Apex 36 Carcass ply 36a Main section 36b Folded section 38 Inner layer 40 outer layer 42 Main groove 44 Ribs CL tire equatorial plane D. Groove depth of the circumferential main grooves formed in the tread

Claims

1. A rubber composition containing wax having an iso component ratio of 15% by mass or less.

2. The rubber composition according to claim 1, wherein the wax is obtained by Fischer-Tropsch synthesis.

3. A rubber composition containing wax obtained by Fischer-Tropsch synthesis.

4. The rubber composition according to claim 2 or 3, wherein the raw material for the Fischer-Tropsch synthesis is sustainable methane or carbon monoxide converted from carbon dioxide.

5. The rubber composition according to claim 4, wherein the sustainable methane is methane produced from feces or industrial wastewater or methane synthesized by methanation.

6. A rubber composition according to any one of claims 1 to 5, comprising plant-derived wax and / or a hydrolyzed product of plant-derived wax.

7. The rubber composition according to claim 6, wherein the plant-derived wax is rice wax.

8. The rubber composition according to claim 6 or 7, wherein the ratio (A / B) of the content A (parts by mass) of wax having an iso component ratio of 15% by mass or less per 100 parts by mass of rubber component to the total content B (parts by mass) of the plant-derived wax and hydrolysate of plant-derived wax per 100 parts by mass of rubber component is 2 or more and 9 or less.

9. A rubber composition for tires, according to any one of claims 1 to 8.

10. The synthesis process for producing wax by Fischer-Tropsch synthesis, A kneading step is performed to knead the wax obtained in the above synthesis step with a rubber component to produce a rubber composition, A method for producing a vulcanized rubber product, comprising a vulcanization step of vulcanizing the rubber composition obtained in the kneading step.

11. The manufacturing method according to claim 10, wherein the vulcanized rubber product is a tire.

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