Vulcanized rubber composition

Abstract

To provide a rubber composition having high crosslinking uniformity and a method for producing the composition.SOLUTION: A vulcanized rubber composition is obtained by a production method including: a base kneading step of kneading at least one kind of rubber component and at least one kind of vulcanization accelerator; a finish kneading step of kneading a kneaded product 1 obtained in the base kneading step and at least one kind of vulcanizer; and a vulcanizing step of vulcanizing a kneaded product 2 obtained in the finish kneading step.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] It is said that the local non-uniformity of the crosslink density of vulcanized rubber affects the physical properties of vulcanized rubber and tire products, and rubber with high crosslink uniformity is expected to be excellent in fracture and abrasion resistance. However, since the analytical methods for evaluating crosslink uniformity are limited and there is no quantitative evaluation index, it is difficult to provide a method for obtaining a crosslink-uniform rubber composition.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Although a crosslink homogenization method has been demanded as described above, since there is no analytical method or evaluation index for crosslink uniformity, it is difficult to develop a homogenization method. In particular, it is desired to provide a crosslink homogenization method that can be generally used for various vulcanized rubber compositions.

[0004] An object of the present invention is to solve the above problems and provide a rubber composition having high crosslink uniformity and a method for producing the same.

Means for Solving the Problems

[0005] The present invention includes a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step, and relates to a vulcanized rubber composition obtained by a production method including these steps.

Effects of the Invention

[0006] The present invention provides a vulcanized rubber composition with high crosslinking uniformity and a manufacturing method thereof, as it is obtained by a manufacturing method including a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step.

Embodiments for Carrying Out the Invention

[0007] The present invention relates to a vulcanized rubber composition (hereinafter also referred to as "vulcanized rubber composition 1") obtained by a manufacturing method (hereinafter also referred to as "manufacturing method 1") including a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the above base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the above finishing kneading step.

[0008] The mechanism by which the above-described vulcanized rubber composition 1 achieves the aforementioned effects is not necessarily clear, but is presumed as follows. In the kneading process of vulcanized rubber production, usually, due to concerns about premature vulcanization, sulfur, vulcanization accelerators, etc. are often added in the finishing kneading step. However, by adding and kneading the vulcanization accelerator in the base kneading step, it is considered that a vulcanized rubber composition with the vulcanization accelerator more uniformly dispersed, a narrow standard deviation of the residual dipole coupling constant, and a more uniform crosslink density distribution is produced. Also, for example, the crosslinking uniformity of vulcanized rubber can be evaluated by measuring the standard deviation of the residual dipole coupling constant using NMR. Therefore, according to the present invention, it is presumed that a rubber composition with high crosslinking uniformity and a manufacturing method thereof can be provided, and for example, a rubber composition with a narrow standard deviation of the residual dipole coupling constant using NMR and a manufacturing method thereof can be provided.

[0009] The above vulcanized rubber composition 1 is obtained by a production method 1 including a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the above base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the above finishing kneading step.

[0010] Hereinafter, the details of each step of the above production method 1 will be described.

[0011] (Base kneading step of the above production method 1) In the base kneading step of the above production method 1, at least one rubber component and at least one vulcanization accelerator are kneaded.

[0012] In the base kneading step of the above production method 1, the input amount of the above at least one rubber component may be the total amount (the total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above production method 1, it is preferable to input and knead 50% by mass or more of the total amount of all types of rubber components, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0013] In the base kneading step of the above production method 1, the input amount of the above at least one vulcanization accelerator may be the total amount (the total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above production method 1, it is preferable to input and knead 50% by mass or more of the total amount of the above at least one vulcanization accelerator, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0014] Among them, for the reason that more effects can be obtained, in the base kneading step of the above manufacturing method 1, it is desirable to knead at least the sulfenamide vulcanization accelerator described below. In this case, it is preferable to add and knead 50% by mass or more of the total amount (total amount used in all steps) of the sulfenamide vulcanization accelerator, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0015] Particularly, in the base kneading step of the above manufacturing method 1, it is desirable to knead at least N-cyclohexyl-2-benzothiazole sulfenamide described below. In this case, it is preferable to add and knead 50% by mass or more of the total amount (total amount used in all steps) of N-cyclohexyl-2-benzothiazole sulfenamide, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0016] In the base kneading step of the above manufacturing method 1, the rubber component and the vulcanization accelerator may be added all at once or separately. For example, after initially kneading a part of the rubber component and the vulcanization accelerator, the remaining parts thereof may be kneaded. Also, after initially kneading a part of the rubber component and all of the vulcanization accelerator, the remaining part of the rubber component may be kneaded, or after initially kneading all of the rubber component and a part of the vulcanization accelerator, the remaining part of the vulcanization accelerator may be kneaded.

[0017] The kneading in the base kneading step of the above manufacturing method 1 may be carried out in one stage or in two or more stages. In the present invention, the one-stage kneading means from when each component is added and kneaded until it is discharged. Therefore, even when each component is added with a time difference until it is discharged, it is a one-stage kneading.

[0018] In the base kneading step of the above manufacturing method 1, at least one kind of rubber component is kneaded. In the present invention, the rubber component is a component that contributes to crosslinking. Generally, a polymer having 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 rubber component is in a solid state at normal temperature (25°C).

[0019] 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.

[0020] In addition, in this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be determined by standard polystyrene conversion based on the measured values by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0021] The rubber component may be an unmodified rubber or a modified rubber. Examples of the modified rubber include rubbers having a functional group that interacts with a filler such as silica. For example, a terminal-modified rubber (terminal-modified rubber having the above functional group at the terminal) in which at least one terminal of the rubber is modified with a compound (modifying agent) having the above functional group, a main-chain modified rubber having the above functional group in the main chain, a main-chain terminal-modified rubber having the above functional group in the main chain and at the terminal (for example, a main-chain terminal-modified rubber having the above functional group in the main chain and at least one terminal modified with the above modifying agent), and a terminal-modified rubber modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or an epoxy group introduced therein, etc. are mentioned.

[0022] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have substituents. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferable.

[0023] Examples of the rubber component include diene rubbers. Examples of the diene rubber include isoprene rubbers, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. Further, examples of the rubber component include butyl rubbers, fluororubbers, etc. These rubber components may be subjected to modification treatment or hydrogenation treatment, and stretched rubbers stretched with oils, resins, liquid rubber components, etc. may be used. These may be used alone or in combination of two or more. Among them, it is preferable to contain at least one of isoprene rubbers, BR, and SBR, more preferably to contain at least SBR, and even more preferably to contain at least isoprene rubbers, BR, and SBR.

[0024] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. As NR, for example, SIR20, RSS#3, TSR20, etc., which are common in the rubber industry, can be used. As IR, there is no particular limitation, and for example, IR2200, etc., which are common in the rubber industry, can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more.

[0025] BR is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more. Among them, BR preferably 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 spectrometry.

[0026] When BR is a single type, the cis amount of BR means the cis amount of that BR, and when there are multiple types, it means the average cis amount. The average cis amount of BR can be calculated by {Σ(content of each BR × cis amount of each BR)} / total content of all BR. For example, in 100% by mass of the rubber component, if BR with a cis amount of 90% by mass is 20% by mass and BR with a cis amount of 40% by mass is 10% by mass, the average cis amount of BR is 73.3% by mass (=(20×90 + 10×40) / (20 + 10)).

[0027] For BR, either non-modified BR or modified BR can be used. Examples of modified BR include modified BR into which the same functional groups as those of modified rubbers are introduced. Also, hydrogenated butadiene polymers (hydrogenated BR) can be used as BR.

[0028] As the BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd. and the like can be used.

[0029] The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) and the like can be used. These may be used alone or in combination of two or more.

[0030] The styrene content of the SBR is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 24% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the styrene content 1 can be measured by 1H-NMR measurement.

[0031] The amount of styrene in the SBR means the amount of styrene in the case where the SBR is of one kind, and means the average amount of styrene in the case of a plurality of kinds. The average amount of styrene in the SBR can be calculated by {Σ(content of each SBR × amount of styrene in each SBR)} / total content of all SBRs. For example, when 85% by mass of SBR having a styrene amount of 40% by mass and 5% by mass of SBR having a styrene amount of 25% by mass are present in 100% by mass of the rubber component, the average amount of styrene in the SBR is 39.2% by mass (=(85×40 + 5×25) / (85 + 5)).

[0032] The vinyl bond amount of the SBR is preferably 3% by mass or more, more preferably 10% by mass or more, still more preferably 17% by mass or more. The vinyl bond amount is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the vinyl bond amount (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0033] The vinyl content of SBR (the amount of 1,2 - bound butadiene units) is the ratio of vinyl bonds when the total mass of the butadiene part in SBR is taken as 100 (unit: mass %), and vinyl content [mass %] + cis content [mass %] + trans content [mass %] = 100 [mass %]. When there is one type of SBR, it means the vinyl content of that SBR; when there are multiple types, it means the average vinyl content. The average vinyl content of SBR can be calculated by 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, in 100 parts by mass of the rubber component, if there are 75 parts by mass of SBR with a styrene content of 40 mass % and a vinyl content of 30 mass %, 15 parts by mass of SBR with a styrene content of 25 mass % and a vinyl content of 20 mass %, and the remaining 10 parts by mass are other than SBR, the average vinyl content of SBR is 28 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 %])}).

[0034] As SBR, either non - modified SBR or modified SBR can be used. Examples of modified SBR include those with functional groups similar to modified rubbers introduced. Also, as SBR, hydrogenated styrene - butadiene copolymer (hydrogenated SBR) can be used.

[0035] As SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. Also, those synthesized by known methods can be used.

[0036] The raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from petroleum, or may be recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled butadiene and recycled aromatic vinyl. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0037] The method for producing recycled monomers is not particularly limited, and examples include being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. 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 high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0038] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. The method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0039] The polymers synthesized from biomass monomer components (biomass polymers) are 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.

[0040] 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.

[0041] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the modern standard reference, and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value is described below.

[0042] In one mole (6.02×10 23 pieces) of carbon atoms, there are approximately 6.02×10 11 pieces of 14 C, which is about one trillionth of the normal carbon atoms. 14 14 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 these to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all of the 14 C elements contained at the time 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

[0043] On the one hand, 14 C undergoes nuclear reactions in the atmosphere by cosmic rays, is constantly generated, and is balanced with the decrease due to radioactive decay. In the atmospheric environment of the earth, 14 the amount of C is a certain amount. Therefore, for substances derived from biomass resources that are circulating in the current environment, 14 the C concentration 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 ratio (biomass ratio) of the compound (biomass resource-derived compound) derived from natural resources in a certain compound (rubber) can be calculated.

[0044] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as the modern standard reference for the C concentration, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) is separated for each carbon isotope, 13 the value of 14 C is corrected to a certain value and the value after decay correction from 1950 AD to the measurement date is used as the standard

[0045] Therefore, if the rubber is made of a 100% biomass (natural) - derived material, although there are regional differences, it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring the 14 C concentration, it will show almost 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0046] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.

[0047] In the base kneading step of the above manufacturing method 1, at least one vulcanization accelerator is kneaded. As the above vulcanization accelerator, those commonly used can be used. The above vulcanization accelerators include, for example, thiazole - type vulcanization accelerators such as 2 - mercaptobenzothiazole, di - 2 - benzothiazolyldisulfide, N - cyclohexyl - 2 - benzothiazylsulfenamide; thiuram - type vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis(2 - ethylhexyl)thiuram disulfide (TOT - N); sulfenamide - type vulcanization accelerators such as N - cyclohexyl - 2 - benzothiazole sulfenamide, N - t - butyl - 2 - benzothiazolylsulfenamide, N - oxyethylene - 2 - benzothiazole sulfenamide, N,N’ - diisopropyl - 2 - benzothiazole sulfenamide; guanidine - type vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, orthotolylbiguanidine. These can be used alone or in combination of two or more.

[0048] Among the above vulcanization accelerators, from the perspective of obtaining more effects, sulfenamide - type vulcanization accelerators are preferred, and N - cyclohexyl - 2 - benzothiazole sulfenamide is more preferred.

[0049] In the base kneading step of the above manufacturing method 1, the input amount of the above vulcanization accelerator is preferably 0.1 part by mass or more, more preferably 1.0 part by mass or more, still more preferably 2.0 part by mass or more, and particularly preferably 2.4 part by mass or more with respect to 100 parts by mass of the input amount of the rubber component. Also, it is preferably 20.0 parts by mass or less, more preferably 5.0 parts by mass or less, and still more preferably 3.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0050] In the base kneading step of the above manufacturing method 1, other components may be added and kneaded in addition to the above rubber component and vulcanization accelerator. Examples of other components other than the above rubber component and vulcanization accelerator include fillers, silane coupling agents, plasticizers, anti-aging agents, stearic acid, zinc oxide, waxes, and the like.

[0051] In the base kneading step of the above manufacturing method 1, the input amount of other components other than the above rubber component and vulcanization accelerator may be the total amount (total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above manufacturing method 1, it is preferable to add and knead 50% by mass or more of the total amount of all types of rubber components, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0052] The above filler is not particularly limited, and materials known in the rubber field can be used. For example, inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, biochar (BIO CHAR); difficult-to-disperse fillers, and the like can be mentioned. Among them, carbon black and silica are preferable from the viewpoint of obtaining more effects.

[0053] The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the manufacturing method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Company, etc. can be used. The carbon black may be used alone or in combination of two or more kinds.

[0054] The nitrogen adsorption specific surface area (N 2 SA) of the carbon black is preferably 5 m 2 / g or more, more preferably 50 m 2 / g or more, and still more preferably 80 m 2 / g or more. Further, the above N 2 SA is preferably 200 m 2 / g or less, more preferably 150 m 2 / g or less, and still more preferably 120 m 2 / g or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the nitrogen adsorption specific surface area of the carbon black is determined according to JIS K6217-2:2001.

[0055] The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited, and for example, it may be a raw material derived from a mineral such as quartz, or it may be a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may be used. Among them, hydrous silica prepared by a wet method is preferable because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0056] Silica using a biomass material as a raw material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to obtain a precipitate of silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0057] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth can be used. The recovery method is not particularly limited, and examples include pyrolysis and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferable.

[0058] When silica crystallizes, it is insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0059] Amorphous silica extracted from rice husk can be a commercially available product from Wilmar Co., Ltd. or the like.

[0060] The nitrogen adsorption specific surface area (N 2 SA) of the above silica is preferably 50 m2 70 m² / g or more, more preferably 70 m² / g or more 2 80 m² / g or more, still more preferably 80 m² / g or more 2 / g or more. Also, the upper limit of the N 2 SA of silica is not particularly limited, but is preferably 350 m² / g or less, more preferably 300 m² / g or less, still more preferably 250 m² / g or less. When it is within the above range, the effect tends to be better obtained. The N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-93. 2 250 m² / g or less. When it is within the above range, the effect tends to be better obtained. 2 When it is within the above range, the effect tends to be better obtained. In addition, the N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0061] The above silane coupling agent is not particularly limited, and those 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,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, etc. of the sulfide type, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto type such as NXT and NXT-Z manufactured by Momentive, vinyl type such as vinyltriethoxysilane and vinyltrimethoxysilane, amino type such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy type such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro type such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. can be mentioned. As commercially available products, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more kinds.

[0062] In this specification, the above-mentioned plasticizer is a material that imparts plasticity to the rubber component, and is a concept that includes both plasticizers that are liquid (in a liquid state) at normal temperature (25°C) and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0063] Specific examples of the above-mentioned plasticizers include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0064] Examples of oils include process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, process oils with a low content of polycyclic aromatic compounds (PCA) can be used for environmental protection. Examples of the low-PCA-content process oils include MES, TDAE, heavy naphthenic oils, etc. Also, from the perspective of life cycle assessment, it is also possible to use waste oils after being used in rubber mixers or engines, or waste cooking oils used in restaurants that have been refined.

[0065] 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, grape seed oil, wood wax, etc. Further, as vegetable oils, there are also 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, oxidation polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0066] 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 hydroxy group of glycerin and a fatty acid are ester-bonded. Acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidation polymerization, etc. Also, acylglycerol may be liquid or solid at normal temperature (25°C).

[0067] The method for confirming whether the above acylglycerol is contained in the rubber composition is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, at room temperature 1When measuring 1H-NMR and setting the signal of tetramethylsilane (TMS) at 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm were observed, and these signals were presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0068] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. 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.

[0069] Among them, it is desirable that the fatty acid contains a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0070] As the oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0071] Examples of the liquid polymer include a liquid diene polymer (liquid rubber) and a liquid farnesene polymer at 25°C. Examples of the liquid rubber include a liquid styrene-butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene-isoprene copolymer (liquid SIR), a liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), a liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), etc. These may have a polar group-modified terminal or main chain. Also, hydrogenated products thereof can be used.

[0072] The weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the liquid diene polymer is preferably 1.0×10 3 ~5.0×10 4 and more preferably 3.0×10 3 ~1.5×10 4 . The lower or upper limit of Mw of the liquid diene polymer may also be 4500 or 8500. In this specification, the Mw of the liquid diene polymer is a polystyrene-converted value measured by gel permeation chromatography (GPC).

[0073] Examples of the liquid diene polymer include products of Sartomer Company and Kuraray Co., Ltd.

[0074] As the above-mentioned resin, as a tire compound, a resin (resin) commonly used can be used, which may be liquid or solid at normal temperature (25°C). For example, aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, acrylic resins, etc. can be mentioned. Further, the resin may be a hydrogenated resin (hydrogenated resin). These may be used alone or in combination of two or more. Also, the resin itself may be a copolymer of monomer components from a plurality of sources. Among them, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins thereof are desirable.

[0075] When using a resin that is solid at normal temperature, the softening point of the above-mentioned resin is preferably 50°C or higher, more preferably 55°C or higher, still more preferably 60°C or higher, and particularly preferably 85°C or higher. Also, it is preferably 160°C or lower, more preferably 150°C or lower, still more preferably 140°C or lower, and particularly preferably 100°C or lower. When within the above range, the effect tends to be obtained more favorably. When the resin is liquid at normal temperature, the softening point is preferably 20°C or lower, preferably 10°C or lower, and preferably 0°C or lower. In the case of a hydrogenated resin, it is desirable that the softening point is the same as above. Note that the softening point of the above-mentioned resin is measured with a ring and ball softening point measuring device for the softening point defined in JIS K6220-1:2001, and is the temperature at which the ball drops.

[0076] The above-mentioned aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constitutional unit. For example, resins obtained by polymerizing α-methylstyrene and / or styrene can be mentioned. Specifically, homopolymers of styrene (styrene resins), homopolymers of α-methylstyrene (α-methylstyrene resins), copolymers of α-methylstyrene and styrene, copolymers of styrene and other monomers, etc. can be mentioned.

[0077] The above-mentioned coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Examples of monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methyl indene, vinyl toluene, and the like.

[0078] The above-mentioned coumarone resin is a resin containing coumarone as the main monomer component constituting the resin skeleton (main chain).

[0079] The above-mentioned indene resin is a resin containing indene as the main monomer component constituting the resin skeleton (main chain).

[0080] As the above-mentioned phenolic resin, for example, known polymers such as those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural in the presence of an acid or alkali catalyst can be used. Among them, those obtained by reacting with an acid catalyst (such as novolak-type phenolic resins) are preferred.

[0081] Examples of the above-mentioned rosin resin include rosin-based resins typified by natural rosin, polymerized rosin, modified rosin, their ester compounds, and their hydrogenated products.

[0082] Examples of the above-mentioned petroleum resin include C5-based resin, C9-based resin, C5 / C9-based resin, dicyclopentadiene (DCPD) resin, C9 / DCPD resin, and their hydrogenated products. Among them, DCPD resin, hydrogenated DCPD resin, C9 / DCPD resin, and C9 / hydrogenated DCPD resin are preferred.

[0083] The above terpene resin is a polymer containing terpenes as constituent units. For example, there are polyterpene resins obtained by polymerizing terpene compounds, aromatic-modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds, and the like. Examples of aromatic-modified terpene resins include terpene phenol resins using terpene compounds and phenolic compounds as raw materials, terpene styrene resins using terpene compounds and styrene compounds as raw materials, and terpene phenol styrene resins using terpene compounds, phenolic compounds, and styrene compounds as raw materials. Examples of terpene compounds include α-pinene, β-pinene, etc., examples of phenolic compounds include phenol, bisphenol A, etc., and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among them, aromatic-modified terpene resins are preferred.

[0084] The above acrylic resin is a polymer containing acrylic monomers as constituent units. For example, there are styrene acrylic resins such as styrene acrylic resins obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component and having a carboxyl group. Among them, a solventless carboxyl group-containing styrene acrylic resin can be preferably used.

[0085] As the above resin, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, ExxonMobil, KRATON, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc. can be used.

[0086] From the perspective of sustainability, it is desirable to use plant-derived plasticizers such as the above plant-derived oils and farnesene-based polymers as the above plasticizer.

[0087] The farnesene-based polymer is a polymer obtained by polymerizing farnesene and has a structural unit 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 having the following structure is preferred.

Chemical formula

[0088] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among them, a copolymer of farnesene and a vinyl monomer is preferred.

[0089] 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, vinyl ethylbenzene, 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, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among them, butadiene is preferred. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred.

[0090] In the farnesene-vinyl monomer copolymer, the copolymerization ratio by mass (farnesene / vinyl monomer) of farnesene and vinyl monomer is preferably 40 / 60 to 90 / 10.

[0091] Farnesene-based polymers can preferably be those having a weight average molecular weight (Mw) of 3,000 or more and 300,000 or less. The Mw of the farnesene-based polymer is preferably 8,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. When within the above range, the effects tend to be more preferably obtained.

[0092] The farnesene-based polymer may be either in a liquid state or a solid state at room temperature (25°C). Among them, a liquid farnesene-based polymer in a liquid state at room temperature (25°C) is desirable.

[0093] The antioxidant is not particularly limited, and examples include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used.

[0094] As the above thearic acid, conventionally known ones can be used. For example, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used.

[0095] As the above zinc oxide, conventionally known ones can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusuitech Co., Ltd., Sho-Doh Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0096] The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and their selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramoelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0097] The kneading method in the base kneading step of the above manufacturing method 1 is not particularly limited, and for example, known kneaders such as Banbury mixers and kneaders can be used. Also, the kneading time (the total kneading time of the base kneading step) is preferably 3 to 20 minutes, and the kneading temperature is preferably 130 to 160°C.

[0098] (The finishing kneading step of the above manufacturing method 1) In the finishing kneading step of the above manufacturing method 1, the kneaded product 1 obtained in the above base kneading step and a vulcanizing agent are kneaded.

[0099] The vulcanizing agent kneaded in the finishing kneading step of the above manufacturing method 1 is not particularly limited as long as it is a chemical capable of crosslinking the rubber component, and examples include sulfur, etc. Also, hybrid crosslinking agents (organic crosslinking agents) can also be used as the vulcanizing agent in the present invention. These may be used alone or in combination of two or more. Among them, sulfur is preferred.

[0100] Examples of the sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys, Nippon Retort Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more kinds.

[0101] In the base kneading step of the above manufacturing method 1, the input amount of the above vulcanizing agent may be the total amount (total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above manufacturing method 1, it is preferable to input and knead 50% by mass or more of the total amount of the above vulcanizing agent, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0102] In the base kneading step of the above manufacturing method 1, the input amount of the above sulfur may be the total amount (total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above manufacturing method 1, it is preferable to input and knead 50% by mass or more of the total amount of the above sulfur, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0103] In the finishing kneading step of the above manufacturing method 1, other components may be input and kneaded in addition to the above vulcanizing agent. Examples of the other components other than the above vulcanizing agent include vulcanization accelerators other than those kneaded in the above base kneading step.

[0104] In the base kneading step of the above manufacturing method 1, the input amount of the vulcanization accelerator other than those kneaded in the above base kneading step may be the total amount (total amount used in all steps) or a part thereof. For the reason that more effects can be obtained, in the base kneading step of the above manufacturing method 1, it is preferable to add and knead 50% by mass or more of the total amount of vulcanization accelerators other than those kneaded in the base kneading step, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0105] The kneading method in the finishing kneading step of the above manufacturing method 1 is not particularly limited. For example, a known kneader such as an open roll can be used. Also, the kneading time is preferably 1 to 15 minutes, and the kneading temperature is preferably 80 to 120°C.

[0106] (Vulcanization step of the above manufacturing method 1) In the vulcanization step of the above manufacturing method 1, the kneaded product 2 obtained in the finishing kneading step is vulcanized.

[0107] In the above vulcanization step, the kneaded product (unvulcanized rubber composition) obtained in the finishing kneading step is vulcanized. In the above vulcanization step, usually, a vulcanization treatment such as press vulcanization is performed, whereby a vulcanized rubber composition (vulcanized rubber composition) is obtained. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C. The vulcanization time is usually 1 to 30 minutes, preferably 5 to 15 minutes.

[0108] The above vulcanization step can be carried out, for example, by extruding the unvulcanized rubber composition according to the shape of a tire member such as a tread, molding it in a normal manner on a tire molding machine, bonding it together with other tire members to form an unvulcanized tire, and then heating and pressurizing it in a vulcanizer to manufacture a tire.

[0109] By the manufacturing method 1 including the above base kneading step, finishing kneading step and vulcanization step, the vulcanized rubber composition (vulcanized rubber composition) of the present invention is obtained.

[0110] In the rubber composition obtained by the above manufacturing method 1, when an isoprene rubber is included as the rubber component, the content of the isoprene rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 12% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0111] In the rubber composition obtained by the above manufacturing method 1, when BR is included as the rubber component, the content of BR in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 7% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0112] In the rubber composition obtained by the above manufacturing method 1, when SBR is included as the rubber component, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, still more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0113] In the rubber composition obtained by the above manufacturing method 1, the content of the above vulcanization accelerator is preferably 0.5 part by mass or more, more preferably 2.0 parts by mass or more, still more preferably 3.0 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, still more preferably 5.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0114] In the rubber composition obtained by the above manufacturing method 1, the content of the above sulfenamide vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, still more preferably 3.0 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, still more preferably 5.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0115] In the rubber composition obtained by the above manufacturing method 1, the content of the above N-cyclohexyl-2-benzothiazole sulfenamide is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2.0 parts by mass or more, particularly preferably 2.4 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 3.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0116] In the rubber composition obtained by the above manufacturing method 1, the content of the above vulcanizing agent is 0.5 parts by mass or more, preferably 1.0 parts by mass or more, more preferably 1.4 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 4.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0117] In the rubber composition obtained by the above manufacturing method 1, the content of the above sulfur is 0.5 parts by mass or more, preferably 1.0 parts by mass or more, more preferably 1.4 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 4.0 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0118] In the rubber composition obtained by the above manufacturing method 1, the content of the filler (total amount of fillers such as carbon black and silica) is preferably 5 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 80 parts by mass or more, and preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 120 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0119] In the rubber composition obtained by the above manufacturing method 1, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0120] In the rubber composition obtained by the above manufacturing method 1, the content of silica is preferably 5 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 80 parts by mass or more, and preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0121] In the rubber composition obtained by the above manufacturing method 1, the content of the silane coupling agent is preferably 0.1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more, based on 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, still more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0122] In the rubber composition obtained by the above manufacturing method 1, the content of the plasticizer (total amount of the plasticizer) is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 35 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 50 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the plasticizer also includes the amount of oil and resin contained in oil-extended rubber and resin-extended rubber.

[0123] In the rubber composition obtained by the above manufacturing method 1, the content of the above resin in a solid state at normal temperature (25 °C) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0124] In the rubber composition obtained by the above manufacturing method 1, the content of the oil is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 35 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the oil also includes the amount of oil contained in oil-extended rubber.

[0125] In the rubber composition obtained by the above manufacturing method 1, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, still more preferably 3.4 parts by mass or more, relative to 100 parts by mass of the rubber component. The content is preferably 10.0 parts by mass or less, more preferably 6.0 parts by mass or less.

[0126] In the rubber composition obtained by the above manufacturing method 1, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, still 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, based on 100 parts by mass of the rubber component.

[0127] In the rubber composition obtained by the above manufacturing method 1, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2.0 parts by mass or more, and preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0128] In the rubber composition obtained by the above manufacturing method 1, the content of wax is preferably 0.5 parts by mass or more, more preferably 1.6 parts by mass or more, and preferably 8.0 parts by mass or less, more preferably 5.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0129] The vulcanized rubber composition 1 obtained by the above manufacturing method 1 preferably has a standard deviation (δ) of the residual dipole coupling constant (Dres) smaller than that of the vulcanized rubber composition (hereinafter also referred to as "vulcanized rubber composition 2") obtained by a manufacturing method (hereinafter also referred to as "manufacturing method 2") including a base kneading step of kneading at least one rubber component in the same formulation (in comparison with a rubber composition in which each compounding component is the same and each compounding component has the same compounding amount), a finishing kneading step of kneading the kneaded product obtained in the above base kneading step, at least one vulcanizing agent, and at least one vulcanization accelerator, and a vulcanization step of vulcanizing the kneaded product obtained in the above finishing kneading step.

[0130] That is, the standard deviation of the residual dipole coupling constant of the vulcanized rubber composition 1 (hereinafter, the residual dipole coupling constant of the vulcanized rubber composition 1 is also referred to as "Dres1") (hereinafter, the standard deviation of the residual dipole coupling constant of the vulcanized rubber composition 1 is also referred to as "δ1"), and the standard deviation of the residual dipole coupling constant of the vulcanized rubber composition 2 (hereinafter, the residual dipole coupling constant of the vulcanized rubber composition 2 is also referred to as "Dres2") (hereinafter, the standard deviation of the residual dipole coupling constant of the vulcanized rubber composition 2 is also referred to as "δ2") preferably satisfy δ1 (Hz) < δ2 (Hz). Here, δ1 / δ2 is preferably 0.990 or less, more preferably 0.988, and still more preferably 0.986 or less. When within the above range, the effect tends to be obtained more favorably.

[0131] The above δ1 is preferably 70 Hz or less, more preferably 68 Hz or less, and still more preferably 67 Hz or less. When within the above range, the effect tends to be obtained more favorably. The lower limit of δ1 is not particularly limited and may be 0 Hz.

[0132] The above Dres1 is preferably 200 Hz or more, more preferably 220 Hz or more, and still more preferably 223 Hz or more, and is preferably 300 Hz or less, more preferably 280 Hz or less, and still more preferably 260 Hz or less. When within the above range, the effect tends to be obtained more favorably.

[0133] In the present invention, the residual dipole coupling constant (Dres) and its standard deviation (σ) can be used as measures reflecting the crosslink density and crosslink density distribution of the vulcanized rubber composition. The dipole referred to here 1 corresponds to H.

[0134] The residual dipole coupling constant is the magnitude of the coupling between the remaining 1 Hs, and 1 H- 1 means the magnitude of the interaction between Hs. 1 H- 1 When the interaction between Hs increases, the value of the residual dipole coupling constant increases. Also, 1 H- 1When the interaction between Hs is small, the value of the residual dipole coupling constant becomes small.

[0135] When the crosslink density increases, 1 H- 1 the interaction between Hs increases and the residual dipole coupling constant increases. Actually, in an isoprene rubber composition containing no filler, when the swelling degree (Swell) and the residual dipole coupling constant (Dres) of samples with different crosslink densities were measured by changing the amount of sulfur and the amount of vulcanization accelerator, when the swelling degree decreased (when the crosslink density increased), the residual dipole coupling constant tended to increase. Thus, the swelling degree, that is, the crosslink density, is correlated with the residual dipole coupling constant.

[0136] As a method for obtaining the residual dipole coupling constant, 1 there is a method of obtaining it from the transverse magnetization decay curve obtained by H-NMR measurement, but there are problems such as difficulty in measurement with a small amount of sample and poor data accuracy due to the influence of fitting errors.

[0137] On the other hand, as a method for obtaining the residual dipole coupling constant and its standard deviation, 1 by using H multiple quantum NMR measurement, even with a small amount of sample, the residual dipole coupling constant and its standard deviation can be obtained. As a result, even with a small amount of sample, the crosslink density and crosslink density distribution of the rubber composition can be accurately evaluated without being affected by the type and amount of filler. That is, 1 by obtaining the residual dipole coupling constant and / or the standard deviation of the residual dipole coupling constant of the rubber composition by H multiple quantum NMR measurement, the crosslink density and / or the crosslink density distribution of the rubber composition can be determined, and the crosslinked state can be analyzed.

[0138] 1By determining the residual dipole coupling constant and / or the standard deviation of the residual dipole coupling constant through H multiple - quantum NMR measurement, it is possible to accurately evaluate the cross - link density and / or the cross - link density distribution with a small amount of sample not only for rubber compositions without fillers but also for rubber compositions containing fillers, as compared with conventional methods such as the toluene swelling method. The reason why the rubber composition containing fillers can be accurately evaluated is considered to be that the residual dipole coupling constant reflects the cross - link density of only the rubber matrix part that is not affected by the filler.

[0139] 1 H multiple - quantum NMR measurement is described, for example, in Saalwachter et al. Journal of Chemical Physics. 119(6). 3468 - 3482. (Literature A) 1 It corresponds to H multiple - quantum nuclear magnetic resonance, etc.

[0140] 1 H multiple - quantum NMR measurement can be carried out, for example, according to the method described in II.EXPERIMENT, B.NMR spectroscopy of the above - mentioned Literature A, and a multiple - quantum growth curve can be obtained by this measurement.

[0141] 1 The multiple - quantum growth curve obtained by H multiple - quantum NMR measurement contains two parameters: the residual dipole coupling constant (Dres) and the standard deviation (σ) of the residual dipole coupling constant.

[0142] The multiple - quantum growth curve can be fitted, for example, by transforming it into the following formula (I). I nDQ means the theoretical curve of the multiple - quantum growth curve. Also, τ DQ is one of the experimental variables related to time.

Equation

[0143] Summarizing the procedure for determining the above residual dipole coupling constant, the following (1) to (2) are obtained. (1) 1 Obtain a multiple quantum growth curve by H multiple quantum NMR measurement. (2) For the multiple quantum growth curve obtained in the experiment, perform fitting with the theoretical curve of the above formula (I) using the residual dipole coupling constant (Dres) and the standard deviation (σ) of the residual dipole coupling constant as variables.

[0144] The molecular structure in the rubber is amorphous, 1 H- 1 The H-H distance is not single. Therefore, 1 H- 1 The magnitude of the H-H interaction is not single either and is considered to have a distribution. Therefore, it is preferable to perform analysis considering the distribution. In the present invention, analysis assuming a distribution has already been performed in the above formula (I).

[0145] 1 There is no particular limitation on the apparatus used for H multiple quantum NMR measurement, but regarding the irradiation magnetic field intensity, it is preferably 75 kHz or higher (more preferably 100 kHz).

[0146] The measurement temperature may be changed depending on the sample, and it is preferable to measure at a temperature 30 °C or higher than the glass transition point of the sample.

[0147] In the above, even when only a small amount of sample can be collected, or when it is desired to measure the difference in crosslink density and its distribution between finer parts in a rubber product, analysis can be performed. Therefore, the amount of the rubber composition of the sample used for measurement may be 0.2 g or less, 0.1 g or less, 0.01 g or less, or 0.005 g or less.

[0148] The rubber composition (sample) measured in the above analysis is not particularly limited, but it may be one collected from a rubber product such as a tire, or may be one collected from a tire.

[0149] The manufacturing method of the present invention is the above-described manufacturing method 1 of a vulcanized rubber composition, which includes a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the above base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the above finishing kneading step. Thereby, a rubber composition with high crosslinking uniformity can be manufactured.

Example

[0150] Hereinafter, examples (Examples) considered preferable in implementation are shown, but the scope of the present invention is not limited to the examples.

[0151] Hereinafter, various chemicals used in the manufacture of tires will be collectively described. The chemicals are purified according to established methods as necessary. NR: TSR20 SBR: HPR850 manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl content: 59% by mass) BR: BR1280 manufactured by LG Chem Carbon black: Diablack N220 (manufactured by Mitsubishi Chemical Corporation, N 2 SA114m 2 / g) Silica: Tokushil USG manufactured by Tokuyama Corporation (N 2 SA: 170m 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Degussa Oil: VIVATEC500 (aromatic process oil) manufactured by H&R Resin 1: SA85 manufactured by Arizona Chemical Company (softening point 85°C, Mw 1000, copolymer of α-methylstyrene and styrene) Resin 2: Petrotac 90 (C5C9-based petroleum resin, Mw 1600, softening point 95°C) manufactured by Tosoh Corporation Wax: Oz Ace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 6C: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Anti-aging agent RD: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powder sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator CZ: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator D: Nocceler D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0152] <Preparation of vulcanized rubber composition> According to the compounding content shown in Table 1, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerator D were kneaded at 150 °C for 5 minutes to obtain kneaded product 1 (base kneading step). Sulfur and vulcanization accelerator D were added to the kneaded product 1, and using an open roll, it was kneaded at 80 °C for 5 minutes to obtain kneaded product 2 (an unvulcanized rubber composition) (finishing kneading step). The kneaded product 2 was vulcanized at 170 °C for 10 minutes to obtain a vulcanized rubber composition (vulcanization step).

[0153] Assuming a vulcanized rubber composition with a changed formulation according to Table 1, the results calculated based on the following evaluation method are shown in Table 1.

[0154] < 1 1H multi-quantum NMR measurement Using a Bruker AVANCE600 manufactured by Bruker (measurement frequency: 600.15 MHz), for the vulcanized rubber composition (sample amount: 4 mg) 1 1H multi-quantum NMR measurement was performed to obtain a multi-quantum growth curve. The measurement is carried out under the conditions of an irradiation magnetic field strength of 125 kHz and a measurement temperature of 80 °C.

[0155] For the multi-quantum growth curve, fitting is performed with the theoretical curve of the above formula (I) to obtain the residual dipole coupling constant Dres and the standard deviation σ of the residual dipole coupling constant.

[0156]

Table 1

[0157] The present invention (1) includes a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, a finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent, and a vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step, and is a vulcanized rubber composition obtained by a production method including these steps.

[0158] The present invention (2) has the same formulation, a base kneading step of kneading at least one rubber component, a finishing kneading step of kneading the kneaded product obtained in the base kneading step, at least one vulcanizing agent, and at least one vulcanization accelerator, and a vulcanization step of vulcanizing the kneaded product obtained in the finishing kneading step, and has a standard deviation of the residual dipole coupling constant smaller than that of the vulcanized rubber composition obtained by a production method including these steps. The vulcanized rubber composition according to the present invention (1).

[0159] The present invention (3) is the vulcanized rubber composition according to the present invention (1) or (2), wherein the base kneading step is a step of kneading at least a sulfenamide-based vulcanization accelerator.

[0160] The present invention (4) is the vulcanized rubber composition according to the present invention (1) or (2), wherein the base kneading step is a step of kneading at least N-cyclohexyl-2-benzothiazolylsulfenamide.

[0161] The present invention (5) is a vulcanized rubber composition which is an arbitrary combination of any one of the present inventions (1) to (3) in which the base kneading step kneads at least isoprene rubber, butadiene rubber, and styrene-butadiene rubber.

[0162] The present invention (6) is a vulcanized rubber composition which is an arbitrary combination of any one of the present inventions (1) to (5) in which the content of isoprene rubber in 100% by mass of the rubber component is 5% by mass or more and 60% by mass or less.

[0163] The present invention (7) is a vulcanized rubber composition which is an arbitrary combination of any one of the present inventions (1) to (6) in which the content of butadiene rubber in 100% by mass of the rubber component is 3% by mass or more and 20% by mass or less.

[0164] The present invention (8) is a vulcanized rubber composition which is an arbitrary combination of any one of the present inventions (1) to (7) in which the content of styrene-butadiene rubber in 100% by mass of the rubber component is 5% by mass or more and 95% by mass or less.

[0165] The present invention (9) is a method for producing a vulcanized rubber composition, comprising: a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator; a finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent; and a vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step.

Claims

1. A base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, A finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent, A vulcanized rubber composition obtained by a production method including a vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step.

2. With the same formulation, A base kneading step of kneading at least one rubber component, A finishing kneading step of kneading the kneaded product obtained in the base kneading step, at least one vulcanizing agent, and at least one vulcanization accelerator, The vulcanized rubber composition according to claim 1, which has a standard deviation of the residual dipole bond constant smaller than the standard deviation of the residual dipole bond constant of the vulcanized rubber composition obtained by a production method including a vulcanization step of vulcanizing the kneaded product obtained in the finishing kneading step.

3. The vulcanized rubber composition according to claim 1, wherein the base kneading step is a step of kneading at least a sulfenamide-based vulcanization accelerator.

4. The vulcanized rubber composition according to claim 1, wherein the base kneading step is a step of kneading at least N-cyclohexyl-2-benzothiazolylsulfenamide.

5. The vulcanized rubber composition according to claim 1, wherein the base kneading step is a step of kneading at least isoprene rubber, butadiene rubber, and styrene-butadiene rubber.

6. The vulcanized rubber composition according to claim 1, wherein the content of isoprene rubber in 100% by mass of the rubber component is 5% by mass or more and 60% by mass or less.

7. The vulcanized rubber composition according to claim 1, wherein the content of butadiene rubber in 100% by mass of the rubber component is 3% by mass or more and 20% by mass or less.

8. The vulcanized rubber composition according to claim 1, wherein the content of styrene-butadiene rubber in 100% by mass of the rubber component is 5% by mass or more and 95% by mass or less.

9. A production method of a vulcanized rubber composition including a base kneading step of kneading at least one rubber component and at least one vulcanization accelerator, A finishing kneading step of kneading the kneaded product 1 obtained in the base kneading step and at least one vulcanizing agent, A vulcanization step of vulcanizing the kneaded product 2 obtained in the finishing kneading step.

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