Rubber composition and method for using polyphenylene ether

Abstract

The purpose of the present invention is to obtain a rubber composition that is excellent in processability, low fuel consumption, wet grip properties, and ice grip properties and has a good balance of these properties at a high level.　To achieve the above, the present invention is characterized by comprising a diene elastomer and a polyphenylene ether having a glass transition temperature measured through differential scanning calorimetry (DSC) of -100°C to less than 0°C.

Description

Rubber composition and method of using polyphenylene ether

[0001] The present invention relates to a rubber composition and a method for using polyphenylene ethers.

[0002] Rubber compositions have been widely used in the fields of industrial parts such as automobile components, tire components, packings, gaskets, sealants, vibration-proof rubber, vibration-isolating rubber, vibration-damping materials, shoe outsoles, and shoe midsoles. Tire treads as tire components are required to have a higher level of reduced rolling resistance (fuel economy) and improved steering stability on wet road surfaces (wet grip). However, fuel economy and wet grip are generally in a trade-off relationship, and it is not easy to achieve both.

[0003] Furthermore, winter tires are also required to have steering stability (ice grip performance) at low temperatures and on icy and snowy roads. Increasing the contact area between the rubber constituting the tire and ice and snow is effective for improving ice grip performance, and therefore, tire rubber is required to have high flexibility. Softeners such as petroleum oils are used to impart flexibility. However, the addition of oil causes bleed-out, which leads to problems of deterioration over time, such as a decrease in ice grip performance. Therefore, additives to replace oil have been proposed. For example, Patent Document 1 discloses a rubber composition containing a rubber component and a farnesene resin in specific proportions, and describes that the composition has good ice grip performance, abrasion resistance, and little change in hardness.

[0004] JP 2014-218631 A

[0005] However, although Patent Document 1 shows an improvement in tire grip performance, it is not sufficient, and there is no description regarding fuel economy. Therefore, further improvement is desired from the viewpoint of obtaining a rubber composition with an excellent balance of properties.

[0006] The present invention has been made in view of the above problems, and aims to provide a rubber composition that achieves high levels of processability, fuel economy, wet grip performance, and ice grip performance all at the same time.

[0007] As a result of intensive research to solve the above problems, the present inventors have found that a rubber composition containing a polyphenylene ether having a specific glass transition temperature can solve the above problems of the conventional technology, and have thus completed the present invention.

[0008] That is, the present invention is as follows: [1] A rubber composition comprising: a polyphenylene ether (A) having a glass transition temperature measured by differential scanning calorimetry (DSC) of −100° C. or more and less than 0° C.; and a diene-based elastomer (B). [2] The rubber composition according to [1], wherein the polyphenylene ether (A) comprises a repeating unit derived from a phenol of the following formula (1) and a repeating unit derived from a phenol of the following formula (2), and the content of the repeating unit derived from a phenol of the following formula (1) is 31 mol % or more and 100 mol %, and the content of the repeating unit derived from a phenol of the following formula (2) is more than 0 mol % and 69 mol % or less, relative to 100 mol % of the total of the repeating units of the following formulas (1) and (2). (In formula (1), R １３ represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms, R １１ and R １２ are each independently any one of a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, and a substituent represented by the following formula (3): (In formula (3), R ３１ each independently form a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R ３１ The atoms contained in R are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms, ３２ are each independently an optionally substituted alkylene group having 1 to 8 carbon atoms, each b is independently 0 or 1, and R ３３ is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group. (In formula (2), R ２１are each independently an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R ２２ are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.) [3] The rubber composition according to [1] or [2], characterized in that the polyphenylene ether (A) has a viscosity of less than 1,000,000 cP at 80°C. [4] The rubber composition according to any one of [1] to [3], characterized in that the polyphenylene ether (A) has a number average molecular weight of less than 5,500. [5] The rubber composition according to any one of [1] to [4], characterized in that the polyphenylene ether (A) contains a biomass-derived monomer. [6] The rubber composition according to any one of [1] to [5], characterized in that the biomass-derived monomer is CNSL. [7] The rubber composition according to any one of [1] to [6], characterized in that the polyphenylene ether (A) is contained in an amount of 0.01 to 65 parts by mass per 100 parts by mass of the diene-based elastomer (B). [8] The rubber composition according to any one of [1] to [7], characterized in that it contains 10 to 115 parts by mass of silica per 100 parts by mass of the diene-based elastomer (B). [9] A method for using a polyphenylene ether, characterized in that it uses, as a raw material for a tire composition, a polyphenylene ether having a glass transition temperature of -100°C or more and less than 0°C as measured by differential scanning calorimetry (DSC).

[10] A method for producing a vulcanized rubber, comprising: mixing a diene-based elastomer (B) with a polyphenylene ether (A) having a glass transition temperature of -100°C or more and less than 0°C as measured by differential scanning calorimetry (DSC) to obtain a rubber composition; and vulcanizing the rubber composition, characterized in that the polyphenylene ether (A) has an unsaturated hydrocarbon group in its side chain, and the diene-based elastomer (B) and the polyphenylene ether (A) undergo a crosslinking reaction.

[0009] According to the present invention, a rubber composition can be obtained that exhibits excellent processability, fuel economy, wet grip performance, and ice grip performance at high levels. Furthermore, according to the present invention, a new method for using polyphenylene ether can be provided.

[0010] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and the present invention is not limited to only this present embodiment, and the present invention can be carried out by appropriately modifying it within the scope of its gist.

[0011] <Rubber Composition> The rubber composition of the present embodiment contains a polyphenylene ether (A) and a diene-based elastomer (B).

[0012] ((A) Polyphenylene Ether) The rubber composition of the present embodiment contains polyphenylene ether, and the polyphenylene ether has a glass transition temperature of −100° C. or higher and lower than 0° C. as measured by DSC.

[0013] The glass transition temperature of the polyphenylene ether as measured by DSC must be −100° C. or higher, preferably −80° C. or higher, and more preferably −50° C. or higher. If the glass transition temperature of the polyphenylene ether as measured by DSC is −100° C. or higher, the balance of the above properties of the resulting rubber composition is highly favorable.

[0014] Furthermore, the glass transition temperature of the polyphenylene ether measured by DSC must be less than 0°C, preferably less than -5°C, and more preferably less than -10°C. If the glass transition temperature of the polyphenylene ether is less than 0°C, the resulting rubber composition will have excellent wet grip and ice grip properties. If the glass transition temperature of the polyphenylene ether is within the above range, it is presumed that compatibility with the diene-based elastomer will be improved, and the above-mentioned effects of the resulting rubber composition will be exhibited. Furthermore, the compatibility between the polyphenylene ether and the diene-based elastomer can be presumed from the high tan δ of the rubber composition of this embodiment. If the compatibility is good, the high tan δ of the rubber composition of this embodiment will not be significantly lower than the high tan δ of a rubber composition to which the polyphenylene ether is not added. Furthermore, the polyphenylene ether (A) may be used alone or in combination of two or more types.

[0015] As a method for adjusting the glass transition temperature measured by DSC, for example, the glass transition temperature can be lowered by molecular design that weakens the interactions between polymer chains and facilitates the movement of the polymer chains. Although not particularly limited, for example, the glass transition temperature can be lowered by introducing a repeating unit having a long-chain alkyl group into polyphenylene ether. Furthermore, the glass transition temperature measured by DSC can be adjusted by appropriately adjusting the introduction ratio of the repeating unit having a long-chain alkyl group or the chain length of the long-chain alkyl group.

[0016] The measuring device for measuring the differential scanning calorimetry is not particularly limited, and a commercially available device can be used. For example, the "DSC250" manufactured by TA Instruments can be used as the differential scanning calorimetry device.

[0017]

[0013] Furthermore, from the viewpoint of improving vulcanization reactivity with the rubber composition, the polyphenylene ether (A) preferably contains a repeating unit derived from a phenol of the following formula (1): Polyphenylene ethers containing a repeating unit derived from a phenol of the following formula (1) have high reactivity because multiple reaction points of the polyphenylene ether are present on side chains projecting outward from the molecular main chain, resulting in less steric hindrance and a higher frequency of collisions between molecules. The improved vulcanization reactivity can increase the vulcanization rate, improve vulcanization adhesion during retreading, and also tend to result in excellent fuel economy, wet grip performance, ice grip performance, tensile strength, and tensile elongation of the rubber composition.

[0018] In the above formula (1), R １３ represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms, R １１ and R １２ are each independently at least one selected from the group consisting of a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, and a substituent represented by formula (3).

[0019] Preferred R １１ and R １２ are each independently at least one selected from a hydrogen atom, a methyl group, an ethyl group, and a substituent represented by formula (3). １１ is a substituent represented by formula (3). Particularly preferably, R １１ is a substituent represented by formula (3), and R １２ is a hydrogen atom. (In formula (3), R ３１ are each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R ３１ The atoms contained therein are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms, and R ３２ are each independently an optionally substituted alkylene group having 1 to 8 carbon atoms, each b is independently 0 or 1, and R ３３ is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group.

[0020] Furthermore, the substituent represented by the above formula (3) is preferably a group containing a secondary and / or tertiary carbon, and examples thereof include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a tert-amyl group, a 2,2-dimethylpropyl group, a cyclohexyl group, and groups in which the hydrogen atom of the terminal hydrocarbon group in these groups has been substituted with a phenyl group. The substituent represented by the above formula (3) is more preferably a tert-butyl group or a cyclohexyl group, and even more preferably a tert-butyl group. Furthermore, the atoms contained in these groups may be bonded to each other to form a cyclic structure.

[0021] In the rubber composition of the present embodiment, in the above formula (1), R １１ is a t-butyl group, and R １２ is preferably a hydrogen atom.

[0022] In the above formula (1), R １３ is an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms, preferably R １３ is C １５ H ３１－２ｎ (wherein each n is independently an integer of 0 to 3).

[0023] From the viewpoint of heat resistance of the resulting rubber composition, the polyphenylene ether may contain a repeating unit derived from a phenol of formula (2) in addition to the repeating unit derived from a phenol of formula (1). (In formula (2), R ２１ are each independently an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R ２２ are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.

[0024] In addition, in the above formula (2), R ２１are each independently preferably a saturated hydrocarbon group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably a methyl group or a phenyl group, and even more preferably a methyl group. ２１ Preferably, both have the same structure.

[0025] Furthermore, in the above formula (2), R ２２ are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a methyl group. ２２ may be the same or different. In a preferred embodiment, two R ２２ and one of them is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (more preferably a methyl group).

[0026] In this embodiment, the structure of polyphenylene ether can be identified by analyzing the polyphenylene ether using techniques such as NMR and mass spectrometry. A specific method for identifying the structure of the polyphenylene ether is to carry out field desorption mass spectrometry (FD-MS), which is known to be less prone to fragmentation, and estimate the repeating units based on the intervals between detected ions. Furthermore, there is a method for estimating the structure of polyphenylene ether by combining peak analysis of fragment ions using electron ionization (EI) and structural analysis by NMR. For example, １ It can be determined using an analytical method such as H NMR.

[0027] In addition, the polyphenylene ether (A) preferably has a content of repeating units derived from phenol of formula (1) of 31 mol% or more and 100 mol% or less, and a content of repeating units derived from phenol of formula (2) of more than 0 mol% and 69 mol% or less, relative to the total 100 mol% of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2). Furthermore, from the viewpoint of improving the processability, fuel economy, wet grip performance, and ice grip performance of the resulting rubber composition while achieving a balance of the above properties, the content of repeating units derived from phenol of formula (1) relative to the total 100 mol% of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more. Meanwhile, there is no upper limit to the content of the repeating units of formula (1).

[0028] The content of the repeating units derived from phenol of the above formula (2) can be appropriately selected depending on the application. For example, when improving heat resistance, the amount of repeating units derived from phenol of the above formula (2) is preferably large. The total molar ratio of the repeating units derived from phenol of the above formula (1) and the repeating units derived from phenol of the above formula (2) relative to 100 mol% of the polyphenylene ether of this embodiment is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and may be 100 mol%.

[0029] The molar ratio of the repeating unit derived from the phenol of the formula (1) and the molar ratio of the repeating unit derived from the phenol of the formula (2) relative to the total of 100 mol % of the repeating unit derived from the phenol of the formula (1) and the repeating unit derived from the phenol of the formula (2) are, for example, １ H-NMR, １３ It can be determined using an analytical method such as C-NMR, and more specifically, it can be measured by the method described in the Examples below.

[0030] The polyphenylene ether (A) may contain a repeating unit derived from a phenol of the following formula (4): In this case, the Tg of the rubber composition can be lowered, thereby further improving wet grip performance and ice grip performance.

[0031] In the above formula (4), R ４１ , R ４２ , R ４３ are each independently a linear saturated hydrocarbon group having 1 to 12 carbon atoms, and an organic group having 7 to 25 carbon atoms and one or more atoms selected from the group consisting of an optionally substituted nitrogen atom, an oxygen atom, and a sulfur atom, and R ４１ , R ４２ , R ４３ At least one of the groups is an organic group having 7 to 25 carbon atoms and having at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

[0032] In addition, in the above formula (4), R ４１ , R ４２ , R ４３ At least one of the above is preferably an organic group having a sulfur atom and having 8 to 20 carbon atoms, and more preferably an organic group having a sulfur atom and having 9 to 15 carbon atoms.

[0033] Furthermore, the phenol of the above formula (4) is preferably specifically 4,6-bis(octylthiomethyl)-o-cresol or 4,6-bis(dodecylthiomethyl)-o-cresol.

[0034] The polyphenylene ether of this embodiment may contain a repeating unit derived from a phenol of the above formula (2) in addition to the repeating unit derived from a phenol of the above formula (4). In the polyphenylene ether of this embodiment, the content of the repeating unit derived from a phenol of the above formula (4) is preferably 7 to 50 mol % and the content of the repeating unit derived from a phenol of the above formula (2) is preferably 50 to 93 mol % relative to 100 mol % in total of the repeating unit derived from a phenol of the above formula (4) and the repeating unit derived from a phenol of the above formula (2).

[0035] From the viewpoint of processability of the resulting rubber composition, the content ratio of the repeating unit derived from the phenol of the above formula (4) relative to the total 100 mol% of the repeating unit derived from the phenol of the above formula (4) and the repeating unit derived from the phenol of the above formula (2) is preferably 7 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more.

[0036] Furthermore, from the viewpoint of fuel economy, wet grip performance, and ice grip performance of the resulting rubber composition, the content ratio of the repeating unit derived from the phenol of the formula (4) above relative to the total 100 mol % of the repeating unit derived from the phenol of the formula (4) above and the repeating unit derived from the phenol of the formula (2) above is preferably 50 mol % or less, more preferably 30 mol % or less, and even more preferably 20 mol % or less.

[0037] The total molar ratio of the repeating units derived from phenol of the above formula (4) and the repeating units derived from phenol of the above formula (2) relative to 100 mol % of the polyphenylene ether of the present embodiment is preferably 80 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and may be 100 mol %.

[0038] The polyphenylene ether in the present embodiment may have at least one partial structure selected from the group consisting of a partial structure of the following formula (10), a partial structure of the following formula (11), a partial structure of the following formula (12), and a partial structure of the following formula (13): (In formula (12), R ４ is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon is R ４ may have a substituent within the range of 1 to 10 carbon atoms in total.) (In formula (13), R ５ is a saturated or unsaturated divalent hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated divalent hydrocarbon is R５ may have a substituent within the range of 1 to 10 carbon atoms in total, and R ６ is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon is R ６ may have a substituent within the range of 1 to 10 carbon atoms in total.)

[0039] At least one partial structure selected from the group consisting of the partial structure of the above formula (10), the partial structure of the above formula (11), the partial structure of the above formula (12), and the partial structure of the above formula (13) may be introduced by a modification step described later, and may be directly bonded to an oxygen atom of a hydroxyl group contained in the polyphenylene ether.

[0040] (Viscosity) From the viewpoint of the processability of the resulting rubber composition, the viscosity of the polyphenylene ether (A) at 80°C is preferably less than 1,000,000 cP, more preferably less than 500,000 cP, and even more preferably less than 300,000 cP. By adjusting the viscosity within the above range, the polyphenylene ether melts during kneading to prepare the rubber composition, improving compatibility with the filler contained in the rubber composition described below, and the rubber composition tends to have excellent fuel economy, wet grip performance, ice grip performance, tensile strength, and tensile elongation. The means for adjusting the viscosity is not particularly limited, and can be adjusted, for example, by changing the molecular weight of the polyphenylene ether (A) or the content ratio of repeating units in the polyphenylene ether (A).

[0041] (Molecular Weight) From the viewpoint of processability of the resulting rubber composition, the number average molecular weight (Mn) of the polyphenylene ether (A) is preferably less than 5500, more preferably less than 5000, and even more preferably less than 4500. When the polyphenylene ether melts during kneading to prepare the rubber composition, compatibility with a filler contained in the rubber composition, which will be described later, can be improved, and the rubber composition tends to have excellent fuel economy, wet grip performance, ice grip performance, tensile strength, and tensile elongation.

[0042] (Reduced Viscosity) The reduced viscosity (ηsp / c) of the polyphenylene ether (A) measured at 30°C using an Ubbelohde viscometer in a chloroform solution having a concentration of 0.5 g / dL is preferably 0.03 to 0.90 dL / g, more preferably 0.05 to 0.60 dL / g, from the viewpoint of processability of the resulting rubber composition. The polyphenylene ether melts during kneading to prepare the rubber composition, which can improve compatibility with a filler contained in the rubber composition described below, and the rubber composition tends to have excellent fuel economy, wet grip properties, ice grip properties, tensile strength, and tensile elongation.

[0043] (Method for Producing Polyphenylene Ether) The polyphenylene ether (A) of the present embodiment can be obtained, for example, by a method including at least a step of oxidatively polymerizing a monovalent starting phenol containing the phenol of the above formula (1). The oxidative polymerization step is preferably a step of oxidatively polymerizing starting phenols containing the phenol of the above formula (1) and the phenol of the above formula (2).

[0044] Examples of the phenol of the above formula (1) include 3-pentadecylphenol, commercially available cardanol, modified 3-pentadecylphenol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by the above formula (3) into 3-pentadecylphenol, and modified cardanol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by the above formula (3) into commercially available cardanol. The substituent to be introduced into the 3-pentadecylphenol or commercially available cardanol is preferably R １１ or by introducing a bulky substituent such as a tert-butyl group or a cyclohexyl group into R １１ and R １２ It is preferable to introduce a methyl group into both R １１ and R １２ Examples of methods for introducing a substituent into include A) a method of reacting with an alkyl halide in the presence of a Lewis acid, and B) a method of reacting with isobutene or the like in the presence of a Bronsted acid. The phenol of formula (1) may be used alone or in combination of two or more types.

[0045] Examples of the phenol of the formula (2) include 2,6-dimethylphenol, 2-methyl-6-ethylphenol, 2,6-diethylphenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-chlorophenol, 2-methyl-6-bromophenol, 2-methyl-6-n-propylphenol, 2-ethyl-6-bromophenol, 2-methyl-6-n-butylphenol, 2,6-di-n-propylphenol, 2-ethyl-6-chlorophenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2-methyl-6-tolylphenol, 2,6-ditolylphenol, 2,3,6-trimethylphenol, 2,3-diethyl-6-n-propylphenol, 2,3,6-tributylphenol, 2,6-di-n-butyl-3-methylphenol, 2,6-dimethyl-3-n-butylphenol, and 2,6-dimethyl-3-t-butylphenol. Among these, 2,6-dimethylphenol, 2,3,6-trimethylphenol, and 2,6-diphenylphenol are particularly preferred because they are inexpensive and easily available. The phenols of formula (2) may be used alone or in combination of two or more.

[0046] The polyphenylene ether (A) can be obtained, for example, by a method including at least a step of oxidatively polymerizing a monovalent starting phenol containing the phenol of formula (4). The oxidative polymerization step is preferably a step of oxidatively polymerizing starting phenols containing the phenol of formula (4) and the phenol of formula (2). Commercially available phenols of formula (4) include 4,6-bis(octylthiomethyl)-o-cresol and 4,6-bis(dodecylthiomethyl)-o-cresol.

[0047] (Biomass, CNSL) The polyphenylene ether preferably contains a biomass-derived monomer from the viewpoint of reducing the environmental impact of the resulting rubber composition. If even a portion of the rubber composition contains biomass-derived raw materials, the amount of fossil fuel used can be reduced compared to conventional methods. The biomass content of the polyphenylene ether can be obtained by measuring the content of biomass-derived carbon using radiocarbon (C14) analysis. Carbon dioxide in the atmosphere contains a certain proportion of C14 (105.5 pMC), and it is known that the C14 content of plants that grow by absorbing carbon dioxide from the atmosphere, such as corn, is also approximately 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, the proportion of biomass-derived carbon can be calculated by measuring the proportion of C14 in the total carbon atoms in the polyphenylene ether.

[0048] The term "biomass" as used herein refers to living organisms, particularly plants such as wood, bamboo, coconuts, and cashew nut shells; polysaccharides such as cellulose, starch, and pullulan; oligosaccharides such as dextrin, sucrose, and maltose; monosaccharides such as fructose and glucose; and plant components such as lignin and hemicellulose. It also includes wood waste from the wood and pulp industries, thinned wood, demolition materials, agricultural waste such as rice straw, husks, and bagasse, and various lignocelluloses, as well as resource rice, old rice, and food industry waste. In this specification, unless otherwise specified, these substances are collectively referred to as "biomass." For example, cardanol obtained from cashew nut shell liquid (CNSL) is an example of a biomass-derived phenolic compound.

[0049] Cashews are a naturally occurring tropical plant whose fruit, cashew nuts, contains protein and carbohydrates and is used as a snack in mixed nuts and in cooking. Cashew nuts are a natural fruit, and when harvested as a resource, they are a renewable biomass resource.

[0050] CNSL is an oily liquid whose main component is cardanol and is contained in cashew nut shells, which are inedible parts obtained as a by-product when harvesting natural cashew nuts used for food.

[0051] Natural CNSL is a mixture of anacardic acid, cardanol, cardol, and 2-methylcardol, and each component is an organic compound consisting of a phenol moiety and a linear hydrocarbon moiety R, as shown in the following formulas (2) to (5). The linear hydrocarbon portion R of each component has one of the following structures. That is, there are four types, with 0, 1, 2, or 3 unsaturated bonds, and an average of two double bonds. R: -(CH ２ ) １４ CH ３ - (CH ２ ) ７ CH=CH(CH ２ ) ５ CH ３ - (CH ２ ) ７ CH=CHCH ２ CH=CH(CH ２ ) ２ CH ３ - (CH ２ ) ７ CH=CHCH ２ CH=CHCH ２ CH=CH ２ Each of the compounds represented by formulas (2) to (5) may be composed of one kind alone or two or more kinds with different R's.

[0052] The main component of natural CNSL is anacardic acid, as shown in formula (2) above. Such natural CNSL is subjected to a decarboxylation treatment for industrial use, resulting in cardanol, as shown in formula (3) above, as the main component. The proportions of each component contained in industrial CNSL vary depending on the place of origin, but are generally 70 to 80% by mass of cardanol (3), 15 to 25% by mass of cardol (4), and 5% by mass or less of 2-methyl cardol (5). The proportion of cardanol can be increased by distilling industrial CNSL.

[0053] In addition, the CNSL used as a raw material for phenol production in this embodiment may be a product in which the unsaturated bond in the linear hydrocarbon moiety R in the side chain of each component represented by the above formulas (2) to (5) has been hydrogenated (hydrogenated) in advance, or a product that has been chemically modified (denatured).

[0054] In the method for producing polyphenylene ether (A), an aromatic solvent that is a good solvent for polyphenylene ether can be used as the polymerization solvent in the oxidative polymerization step.

[0055] Here, a good solvent for polyphenylene ether is a solvent that can dissolve polyphenylene ether, and examples of such solvents include aromatic hydrocarbons such as benzene, toluene, xylene (including o-, m-, and p-isomers), and ethylbenzene; halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; and nitro compounds such as nitrobenzene.

[0056] The polymerization catalyst used in this embodiment may be a known catalyst system that can generally be used for producing polyphenylene ether. Commonly known catalyst systems include those that consist of a transition metal ion having oxidation-reduction ability and an amine compound that can form a complex with the transition metal ion, such as a catalyst system consisting of a copper compound and an amine compound, a catalyst system consisting of a manganese compound and an amine compound, or a catalyst system consisting of a cobalt compound and an amine compound. Because the polymerization reaction proceeds efficiently under slightly alkaline conditions, a small amount of alkali or an additional amine compound may be added.

[0057] The polymerization catalyst preferably used in the present embodiment is a catalyst containing a copper compound, a halogen compound, and an amine compound as catalyst components, and more preferably a catalyst containing a diamine compound represented by the following formula (14) as the amine compound: (In formula (14), R １４ , R １５ , R １６ , R １７ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, but are not all hydrogen atoms at the same time.１８ is a linear or methyl-branched alkylene group having 2 to 5 carbon atoms.

[0058] Examples of copper compounds for the catalyst components described herein are listed below. Suitable copper compounds include cuprous compounds, cupric compounds, and mixtures thereof. Examples of cupric compounds include cupric chloride, cupric bromide, cupric sulfate, and cupric nitrate. Examples of cuprous compounds include cuprous chloride, cuprous bromide, and cuprous sulfate. Among these, particularly preferred metal compounds are cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide. These copper salts may also be synthesized immediately upon use from an oxide (e.g., cuprous oxide), carbonate, hydroxide, or the like and the corresponding halogen or acid. A frequently used method is to mix the cuprous oxide exemplified above with hydrogen halide (or a hydrogen halide solution).

[0059] Examples of the halogen compounds include hydrogen chloride, hydrogen bromide, hydrogen iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium iodide. These compounds can be used as aqueous solutions or solutions using appropriate solvents. These halogen compounds can be used alone or in combination of two or more. Preferred halogen compounds are aqueous solutions of hydrogen chloride and hydrogen bromide.

[0060] The amount of these compounds used is not particularly limited, but is preferably in the range of 2 to 20 times, more preferably 2 to 15 times, and even more preferably 2 to 10 times, the number of moles of halogen atoms relative to the number of moles of copper atoms. The amount of copper atoms used relative to 100 moles of the phenol compound added to the polymerization reaction is preferably in the range of 0.02 to 0.6 moles, more preferably 0.02 to 0.5 moles, and even more preferably 0.02 to 0.4 moles. Next, examples of the diamine compound of the catalyst component are listed. For example, N,N,N',N'-tetramethylethylenediamine, N,N,N'-trimethylethylenediamine, N,N'-dimethylethylenediamine, N,N-dimethylethylenediamine, N-methylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N'-triethylethylenediamine, N,N'-diethylethylenediamine, N,N-diethylethylenediamine, N-ethylethylenediamine, N,N-dimethyl-N'-ethylethylenediamine, N,N'-dimethyl-N-ethylethylenediamine, N-n-propylethylenediamine, N,N'-n-propylethylenediamine, N-i-propylethylenediamine, N,N'-i-propylethylenediamine, N-n-butylethylenediamine amine, N,N'-n-butylethylenediamine, Ni-butylethylenediamine, N,N'-i-butylethylenediamine, N-t-butylethylenediamine, N,N'-t-butylethylenediamine, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N'-trimethyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N-methyl-1,3-diaminopropane, N,N,N',N'-tetramethyl-1,3-diamino-1-methylpropane, N,N,N',N'-tetramethyl-1,3-diamino-2-methylpropane, N,N,N',N'-tetramethyl-1,4-diaminobutane, and N,N,N',N'-tetramethyl-1,5-diaminopentane. A preferred diamine compound for this embodiment is one in which the alkylene group connecting the two nitrogen atoms has 2 or 3 carbon atoms.The amount of these diamine compounds used is not particularly limited, but is preferably in the range of 0.01 to 10 moles, more preferably 0.01 to 8.0 moles, and even more preferably 0.01 to 6 moles, per 100 moles of the phenol compound added to the polymerization reaction.

[0061] In this embodiment, the polymerization catalyst may contain a primary amine and a secondary monoamine as components thereof. Examples of the secondary monoamine include, but are not limited to, dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-butylamine, di-t-butylamine, dipentylamines, dihexylamines, dioctylamines, didecylamines, dibenzylamines, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N-(m-methylphenyl)ethanolamine, N-(p-methylphenyl)ethanolamine, N-(2',6'-dimethylphenyl)ethanolamine, N-(p-chlorophenyl)ethanolamine, N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2,6-dimethylaniline, and diphenylamine.

[0062] The polymerization catalyst may also contain a tertiary monoamine compound as a constituent component. Tertiary monoamine compounds are aliphatic tertiary amines, including alicyclic tertiary amines. Examples include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropylamine, and N-methylcyclohexylamine. These tertiary monoamines may be used alone or in combination of two or more. The amount of these compounds used is not particularly limited, but is preferably 15 mol or less, more preferably 14 mol or less, and even more preferably 13 mol or less, per 100 mol of the phenol compound added to the polymerization reaction.

[0063] In this embodiment, there is no limitation on the addition of surfactants known to have the effect of improving polymerization activity. Examples of such surfactants include trioctylmethylammonium chloride, known under the trade names Aliquat 336 and Capriquat. The amount used is preferably within a range not exceeding 0.1% by mass relative to 100% by mass of the total amount of the polymerization reaction mixture. Examples of oxygen-containing gases that can be used in the polymerization of this embodiment include pure oxygen, mixtures of oxygen and inert gases such as nitrogen in any ratio, air, and mixtures of air and inert gases such as nitrogen in any ratio. Normal pressure is sufficient for the system pressure during the polymerization reaction, but reduced or increased pressure can also be used as necessary. The polymerization temperature is not particularly limited, but is preferably in the range of 0 to 60°C, preferably 10 to 40°C, because too low a temperature will retard the reaction, while too high a temperature may result in reduced reaction selectivity or gel formation.

[0064] In the method for producing the polyphenylene ether (A), the polymerization can also be carried out in a poor solvent such as alcohol.

[0065] In this embodiment, there are no particular limitations on the post-treatment method after the polymerization reaction is completed. Typically, an acid such as hydrochloric acid or acetic acid, or ethylenediaminetetraacetic acid (EDTA) and its salts, nitrilotriacetic acid and its salts, or the like is added to the reaction solution to deactivate the catalyst. Furthermore, a conventionally known method can be used to remove the dihydric phenol by-products generated by the polymerization of polyphenylene ether. As described above, if the metal ions serving as the catalyst are substantially deactivated, the mixture can be decolorized simply by heating. Alternatively, a method of adding a required amount of a known reducing agent is also possible. Examples of known reducing agents include hydroquinone and sodium dithionite.

[0066] In the method for producing the polyphenylene ether (A), water may be added to extract the compound that has deactivated the copper catalyst, and liquid-liquid separation may be performed into an organic phase and an aqueous phase, followed by removing the aqueous phase to remove the copper catalyst from the organic phase. This liquid-liquid separation step is not particularly limited, and examples thereof include static separation and separation using a centrifuge. In order to promote the liquid-liquid separation, a known surfactant or the like may be used.

[0067] Subsequently, in the method for producing the polyphenylene ether (A), the organic phase containing the polyphenylene ether after the liquid-liquid separation may be concentrated and dried by volatilizing the solvent.

[0068] The method for volatilizing the solvent contained in the organic phase is not particularly limited, and examples include a method of transferring the organic phase to a high-temperature concentration tank and distilling off the solvent to concentrate it, and a method of distilling off toluene using an apparatus such as a rotary evaporator to concentrate it. From the viewpoint of suppressing thermal deterioration due to heating, low-temperature concentration under reduced pressure is more preferable. The temperature of the drying treatment in the drying step is preferably at least 60°C or higher, more preferably 80°C or higher, and even more preferably 110°C or higher. When the polyphenylene ether is dried at a temperature of 60°C or higher, the content of high-boiling-point volatile components in the polyphenylene ether powder can be efficiently reduced. From the viewpoint of preventing deterioration due to heat, the temperature is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower.

[0069] In order to obtain the polyphenylene ether with high efficiency, a method of increasing the drying temperature, a method of increasing the degree of vacuum in the drying atmosphere, a method of stirring during drying, and the like are effective, but a method of increasing the drying temperature is particularly preferred from the viewpoint of production efficiency. In the drying step, it is preferable to use a dryer equipped with a mixing function. Examples of the mixing function include a stirring type dryer and a tumbling type dryer. This allows the processing amount to be increased and productivity to be maintained at a high level.

[0070] (Residual Solvent) From the viewpoint of reducing the odor of the resulting polyphenylene ether, the total amount of solvent remaining in the polyphenylene ether (A) is preferably less than 1 mass %, more preferably less than 0.6 mass %, even more preferably less than 0.5 mass %, particularly preferably less than 0.3 mass %, and particularly preferably less than 0.1 mass % of the total amount.

[0071] (Residual Metal) From the viewpoint of suppressing thermal degradation of the resulting polyphenylene ether, the polyphenylene ether (A) preferably has a residual metal catalyst content of less than 1.0 ppm, more preferably less than 0.5 ppm.

[0072] (Residual Amines) From the viewpoint of reducing the odor of the resulting polyphenylene ether, the total amount of amines remaining in the polyphenylene ether (A) is preferably less than 1.0% by mass of the total amount, more preferably less than 0.5% by mass, and even more preferably less than 0.1% by mass. The residual amine amount here refers to the amount of amines remaining in the polyphenylene ether after the drying step, excluding amines chemically bonded to the polyphenylene ether, out of the total amount of amines contained in the polyphenylene ether.

[0073] (Residual Monomer) From the viewpoint of reducing the odor of the resulting polyphenylene ether, the polyphenylene ether (A) preferably has a residual monomer content of less than 5 mass %, more preferably less than 4 mass %, and even more preferably less than 3 mass %.

[0074] The polyphenylene ether (A) can also be produced by a redistribution reaction in which a polyphenylene ether derived from a phenol of formula (2) is equilibrated with a phenol compound of formula (1) in the presence of an oxidizing agent. Redistribution reactions are known in the art and are described, for example, in U.S. Pat. No. 3,496,236 to Cooper et al. and U.S. Pat. No. 5,880,221 to Liska et al.

[0075] There is no limitation on the method for introducing a functional group into a hydroxyl group of an unmodified polyphenylene ether. For example, the unmodified polyphenylene ether can be obtained by a reaction to form an ester bond between a hydroxyl group of the unmodified polyphenylene ether and a carboxylic acid having a carbon-carbon double bond (hereinafter referred to as carboxylic acid).

[0076] Furthermore, various known methods can be used to form the ester bond, such as a) a reaction between a carboxylic acid halide and a hydroxyl group at the end of the polymer, b) formation of an ester bond by reaction with a carboxylic acid anhydride, c) a direct reaction with a carboxylic acid, and d) a method using a transesterification reaction.

[0077] The reaction of a with an carboxylic acid halide is one of the most common methods. Chlorides and bromides are commonly used as carboxylic acid halides, but other halogens may also be used. The reaction may be a direct reaction with a hydroxyl group or a reaction with an alkali metal salt of a hydroxyl group. Since a direct reaction between an carboxylic acid halide and a hydroxyl group generates an acid such as hydrogen halide, a weak base such as an amine may be present to trap the acid.

[0078] In the reaction of b with a carboxylic acid anhydride or the direct reaction of c with a carboxylic acid, a compound such as a carbodiimide or dimethylaminopyridine may be present in order to activate the reaction site and promote the reaction.

[0079] In the case of the transesterification reaction of d, it is desirable to remove the produced alcohols as necessary. Furthermore, known metal catalysts may be used in the presence of the catalyst to promote the reaction. After the reaction, the reaction mixture may be washed with water, an acidic, or an alkaline aqueous solution to remove by-products such as amine salts, or the polymer solution may be dropped into a poor solvent such as an alcohol to recover the target product by reprecipitation. After washing the polymer solution, the solvent may be distilled off under reduced pressure to recover the polymer.

[0080] The method for producing the modified polyphenylene ether is not limited to the method for producing the polyfunctional modified polyphenylene ether of the present embodiment described above, and the order and number of the above-mentioned oxidative polymerization step, copper extraction and by-product removal step, liquid-liquid separation step, and concentration / drying step may be appropriately adjusted. Note that the modified polyphenylene ether may be obtained by oxidatively polymerizing 3-pentadecylphenol or commercially available cardanol, and optionally 2,6-dimethylphenol as the phenol of the formula (2), and then introducing at least one partial structure selected from the group consisting of the formulas (10), (11), (12), and (13) into the obtained polyphenylene ether. The polyphenylene ether of the present embodiment may also be obtained by oxidatively polymerizing modified 3-pentadecylphenol or modified cardanol as the phenol of the formula (1), and optionally 2,6-dimethylphenol as the phenol of the formula (2). Further, for example, the polyphenylene ether of the present embodiment may be obtained by oxidatively polymerizing modified 3-pentadecylphenol or modified cardanol as the phenol of the above formula (1), and optionally 2,6-dimethylphenol as the phenol of the above formula (2), and then introducing at least one partial structure selected from the group consisting of the above formula (10), the above formula (11), the above formula (12), and the above formula (13) into the obtained polyphenylene ether.

[0081] Further, for example, the polyphenylene ether of the present embodiment may be obtained by oxidatively polymerizing 4,6-bis(octylthiomethyl)-o-cresol or 4,6-bis(dodecylthiomethyl)-o-cresol as the phenol of the above formula (4), and optionally 2,6-dimethylphenol as the phenol of the above formula (2), and then introducing at least one partial structure selected from the group consisting of the above formula (10), formula (11), formula (12), and formula (13) into the obtained polyphenylene ether.

[0082] ((B) Diene-Based Elastomer) The diene-based elastomer (B) is selected from at least one of synthetic rubber and natural rubber. The synthetic rubber and natural rubber may be used alone or in combination of two or more. The diene-based elastomer (B) of this embodiment preferably has a weight-average molecular weight of 100,000 or more, more preferably 120,000 or more, and even more preferably 150,000 or more.

[0083] Examples of the synthetic rubber include styrene butadiene rubber (hereinafter also referred to as "SBR"), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile polymer rubber, and chloroprene rubber. Among these, SBR, isoprene rubber, and butadiene rubber are preferred, and SBR and butadiene rubber are more preferred. These may be used alone or in combination of two or more. Note that the diene-based elastomer of this embodiment does not contain a polymer block consisting only of vinyl aromatic monomer units.

[0084] Styrene-butadiene rubber (SBR) The SBR can be any commonly used SBR for tires. Specifically, SBRs with a styrene content of 0.1 to 70% by mass are preferred, more preferably 5 to 60% by mass, and even more preferably 5 to 50% by mass. Furthermore, SBRs with a vinyl content of 0.1 to 80% by mass are preferred, and even more preferably 5 to 70% by mass. Hereinafter, the vinyl content of SBR refers to the content of monomer units having a vinyl group among all butadiene-derived units contained in the SBR. Similarly, the vinyl content of the diene elastomer (B) refers to the content of monomer units actually having a vinyl group relative to the total amount of monomer units that may have a vinyl group due to their bonding form.

[0085] The weight average molecular weight (Mw) of the SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and even more preferably 150,000 to 1,500,000. When the weight average molecular weight (Mw) of the SBR is within the above range, the processability of the rubber composition is improved, and the ice gripping performance of a tire obtained from the rubber composition is improved, and further, the mechanical strength, abrasion resistance, and steering stability are also improved. Note that the weight average molecular weight (Mw) in this specification is a value measured by GPC.

[0086] The glass transition temperature (Tg) of the SBR determined by differential thermal analysis is preferably −95 to 0° C., more preferably −95 to −5° C., even more preferably −95 to −10° C., still more preferably −95 to −15° C., and still more preferably −95 to −20° C. When the glass transition temperature is within the above range, an increase in the viscosity of the rubber composition can be suppressed, making it easier to handle.

[0087] There are no particular limitations on the method for producing the SBR, and any of emulsion polymerization, solution polymerization, gas phase polymerization and bulk polymerization can be used, with emulsion polymerization and solution polymerization being particularly preferred.

[0088] (i) Emulsion-Polymerized Styrene-Butadiene Rubber (E-SBR) E-SBR can be produced by a conventional emulsion polymerization method. For example, predetermined amounts of styrene and butadiene monomers are emulsified and dispersed in the presence of an emulsifier, followed by emulsion polymerization using a radical polymerization initiator. Examples of the emulsifier include salts of long-chain fatty acids having 10 or more carbon atoms or rosinate salts. Specific examples include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid. Water is typically used as the dispersion medium, and may contain water-soluble organic solvents such as methanol and ethanol to the extent that stability during polymerization is not impaired. Examples of the radical polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, and hydrogen peroxide. A chain transfer agent can also be used to adjust the molecular weight of the resulting E-SBR. Examples of chain transfer agents include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpenes, terpinolene, γ-terpinene, and α-methylstyrene dimer. The temperature of the emulsion polymerization can be appropriately selected depending on the type of radical polymerization initiator used, but is typically preferably 0 to 100°C, more preferably 0 to 60°C. The polymerization method may be either continuous or batch polymerization. The polymerization reaction can be terminated by adding a polymerization terminator. Examples of polymerization terminators include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine, and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; and sodium nitrite. After the polymerization reaction has been terminated, an antioxidant may be added as needed. After the polymerization reaction is stopped, unreacted monomers are removed from the obtained latex as needed, and then the polymer is coagulated using a salt such as sodium chloride, calcium chloride, or potassium chloride as a coagulant, and an acid such as nitric acid or sulfuric acid is added as needed to adjust the pH of the coagulation system to a predetermined value, and the dispersion solvent is then separated to recover the polymer as crumbs. The crumbs are washed with water, dehydrated, and dried with a band dryer or the like to obtain E-SBR. During coagulation, the latex may be mixed with an extender oil previously emulsified and dispersed, if needed, and recovered as oil-extended rubber.

[0089] (ii) Solution-Polymerized Styrene-Butadiene Rubber (S-SBR) S-SBR can be produced by a conventional solution polymerization method. For example, styrene and butadiene are polymerized in a solvent using an anionically polymerizable active metal, optionally in the presence of a polar compound. Examples of anionically polymerizable active metals include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among these, alkali metals and alkaline earth metals are preferred, with alkali metals being more preferred. Furthermore, among alkali metals, organic alkali metal compounds are more preferred. Examples of solvents include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane, and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; and aromatic hydrocarbons such as benzene and toluene. These solvents are preferably used in a range such that the monomer concentration is 1 to 50% by mass. Examples of organic alkali metal compounds include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; polyfunctional organic lithium compounds such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; sodium naphthalene, and potassium naphthalene. Among these, organic lithium compounds are preferred, and organic monolithium compounds are more preferred. The amount of the organic alkali metal compound used is determined appropriately depending on the molecular weight of the required S-SBR. The organic alkali metal compound can also be reacted with a secondary amine such as dibutylamine, dihexylamine, or dibenzylamine to be used as an organic alkali metal amide.The polar compound is not particularly limited as long as it is one that is commonly used in anionic polymerization to adjust the microstructure of butadiene moieties and the distribution of styrene in the polymer chain without deactivating the reaction. Examples include ether compounds such as dibutyl ether, tetrahydrofuran, and ethylene glycol diethyl ether; tertiary amines such as tetramethylethylenediamine and trimethylamine; alkali metal alkoxides, and phosphine compounds. The polymerization reaction temperature is typically −80 to 150°C, preferably 0 to 100°C, and more preferably 30 to 90°C. The polymerization method may be either batch polymerization or continuous polymerization. In addition, to improve the random copolymerization of styrene and butadiene, it is preferable to continuously or intermittently supply styrene and butadiene to the reaction solution so that the composition ratio of styrene and butadiene in the polymerization system falls within a specific range. The polymerization reaction can be terminated by adding an alcohol such as methanol or isopropanol as a polymerization terminator. Before adding the polymerization terminator, a coupling agent capable of reacting with the active polymerization terminals, such as tin tetrachloride, tetrachlorosilane, tetramethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, or 2,4-tolylene diisocyanate, or a polymerization terminal modifier, such as 4,4'-bis(diethylamino)benzophenone or N-vinylpyrrolidone, may be added. After the polymerization reaction has been terminated, the solvent can be separated from the polymerization solution by direct drying or steam stripping, and the target S-SBR can be recovered. Note that, before removing the solvent, the polymerization solution may be mixed with an extender oil in advance, and the resultant product may be recovered as an oil-extended rubber.

[0090] (iii) Modified Styrene Butadiene Rubber (Modified SBR) In this embodiment, modified SBR may be used, in which a functional group has been introduced into SBR. Examples of functional groups include amino groups, alkoxysilyl groups, hydroxy groups, epoxy groups, and carboxyl groups. Modified SBR can be produced, for example, by adding a coupling agent capable of reacting with the active polymerization terminals, such as tin tetrachloride, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, or 2,4-tolylenediisocyanate; a polymerization terminal modifier such as 4,4'-bis(diethylamino)benzophenone or N-vinylpyrrolidone; or another modifier described in JP 2011-132298 A, before adding a polymerization terminator. In this modified SBR, the position of the polymer into which the functional group is introduced may be the polymerization terminal or a side chain of the polymer chain.

[0091] Isoprene Rubber: Examples of the isoprene rubber that can be used include commercially available isoprene rubber polymerized using Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; lanthanoid rare earth metal catalysts such as triethylaluminum-organic acid neodymium-Lewis acid; or organic alkali metal compounds, similar to S-SBR. Isoprene rubber polymerized using a Ziegler catalyst has a high cis-isomer content and is therefore preferred. Isoprene rubber with an ultra-high cis-isomer content obtained using a lanthanoid rare earth metal catalyst may also be used.

[0092] The vinyl content of the isoprene rubber is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. A vinyl content exceeding 50% by mass tends to result in poor fuel economy. The lower limit of the vinyl content is not particularly limited. The glass transition temperature varies depending on the vinyl content, but is preferably -20°C or less, and more preferably -30°C or less. The weight-average molecular weight (Mw) of the isoprene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When the weight-average molecular weight of the isoprene rubber is within the above range, the processability of the rubber composition is improved, as is its ice gripping properties, and its handling stability. The isoprene rubber may have a branched structure or polar functional groups formed by using a polyfunctional modifier, such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group-containing alkoxysilane.

[0093] Butadiene Rubber: Examples of butadiene rubbers that can be used include commercially available butadiene rubbers polymerized using Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel catalysts; lanthanoid-based rare earth metal catalysts such as triethylaluminum-organic neodymium-Lewis acid catalysts; or organic alkali metal compounds, as with S-SBR. Butadiene rubbers polymerized using Ziegler catalysts have a high cis content and are preferred. Alternatively, butadiene rubbers with an ultra-high cis content (e.g., cis content of 95% or more) obtained using lanthanoid-based rare earth metal catalysts may also be used. The vinyl content of the butadiene rubber is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. A vinyl content exceeding 50% by mass tends to result in poor fuel economy. There is no particular lower limit for the vinyl content. The glass transition temperature varies depending on the vinyl content, but is preferably −40° C. or lower, more preferably −50° C. or lower.

[0094] The weight-average molecular weight (Mw) of the butadiene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When the weight-average molecular weight (Mw) of the butadiene rubber is within the above range, the processability of the rubber composition is improved, and ice grip and handling stability are also improved. The butadiene rubber may have a branched structure or polar functional groups formed by using a polyfunctional modifier, such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group-containing alkoxysilane. In addition to at least one of SBR, isoprene rubber, and butadiene rubber, one or more of butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile polymer rubber, chloroprene rubber, etc. may be used. Furthermore, the manufacturing method of these rubbers is not particularly limited, and commercially available rubbers may be used.

[0095] Natural Rubber Examples of natural rubbers used in the diene elastomer (B) include TSRs such as SMR, SIR, and STR, natural rubbers commonly used in the tire industry such as RSS, and modified natural rubbers such as high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, and grafted natural rubber. Among these, SMR20, STR20, and RSS#3 are preferred from the viewpoints of less variation in quality and ease of availability. These may be used alone or in combination of two or more.

[0096] From the viewpoints of processability, fuel economy, wet grip performance, and ice grip performance of the resulting rubber composition, the polyphenylene ether (A) is preferably contained in an amount of 0.01 to 65 parts by mass, more preferably 0.01 to 60 parts by mass, and even more preferably 0.01 to 55 parts by mass per 100 parts by mass of the diene elastomer (B). Note that a rubber composition containing more than 65 parts by mass of the polyphenylene ether (A) per 100 parts by mass of the diene elastomer (B) tends to be inferior in fuel economy, wet grip performance, and ice grip performance.

[0097] (Other Components) The rubber composition of the present embodiment may contain other components such as a filler, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, and a vulcanization aid in addition to the polyphenylene ether and diene-based elastomer described above, as long as the effects of the present invention are not impaired.

[0098] The filler is not particularly limited as long as it is one that is commonly used in rubber compositions, but from the viewpoint of improving the dispersibility of the filler in the rubber composition and improving fuel economy and gripping properties, it is preferable that the filler contains at least one selected from silica and carbon black.

[0099] Examples of the silica include wet silica (hydrated silica), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred from the viewpoint of further improving the fuel economy and grip of the rubber composition. These may be used alone or in combination of two or more.

[0100] From the viewpoint of improving the processability, fuel economy, moldability, abrasion resistance, and grip of the rubber composition, the average particle size of the silica is preferably 0.5 nm or more, more preferably 2 nm or more, even more preferably 5 nm or more, still more preferably 8 nm or more, and still more preferably 10 nm or more, and is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 30 nm or less, and still more preferably 20 nm or less. The average particle size of the silica can be determined by measuring the particle diameters with a transmission electron microscope and calculating the average value.

[0101] Carbon Black Examples of the carbon black that can be used include furnace black, channel black, thermal black, acetylene black, and ketjen black. Among these, furnace black is preferred from the viewpoint of improving the fuel economy and grip of the rubber composition.

[0102] Commercially available furnace black products that can be used in the present embodiment include, for example, "Diablack" manufactured by Mitsubishi Chemical Corporation and "Seast" manufactured by Tokai Carbon Co., Ltd. Commercially available acetylene black products include, for example, "Denka Black" manufactured by Denki Kagaku Kogyo Co., Ltd. Commercially available ketjen black products include, for example, "ECP600JD" manufactured by Lion Corporation.

[0103] The average particle size of the carbon black is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, from the viewpoint of improving the fuel economy, moldability, abrasion resistance, and gripping properties of the rubber composition, and is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 70 nm or less, and even more preferably 60 nm or less. The average particle size of the carbon black can be determined by measuring the particle diameters using a transmission electron microscope and calculating the average value. The particle size of the carbon black can be adjusted by pulverization or the like. For pulverizing the carbon black, high-speed rotary pulverizers (hammer mills, pin mills, cage mills), various ball mills (tumbling mills, vibration mills, planetary mills), stirring mills (bead mills, attritors, flow-tube mills, annular mills), etc. can be used. From the viewpoint of improving the wettability and dispersibility of the carbon black in the polyphenylene ether (A) and the diene-based elastomer (B), the carbon black may be subjected to an acid treatment with nitric acid, sulfuric acid, hydrochloric acid, or a mixed acid thereof, or a surface oxidation treatment by heat treatment in the presence of air. In the present invention, from the viewpoint of improving mechanical strength, heat treatment may be performed at 2,000 to 3,000° C. in the presence of a graphitization catalyst. Suitable graphitization catalysts include boron, boron oxides (e.g., BO, BO, BO, BO, etc.), boron oxoacids (e.g., orthoboric acid, metaboric acid, tetraboric acid, etc.) and salts thereof, boron carbides (e.g., BC, BC), boron nitride (BN), and other boron compounds.

[0104] Other Fillers In the present invention, fillers other than silica and carbon black may be contained for the purposes of improving the mechanical strength of the rubber composition and reducing production costs by incorporating the filler as an extender. Examples of fillers other than silica and carbon black that can be used include organic fillers and inorganic fillers such as clay, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, glass fiber, fibrous fillers, and glass balloons. These fillers may be used alone or in combination of two or more.

[0105] Furthermore, when the filler is compounded in the rubber composition of this embodiment, the content of the filler is preferably 20 to 150 parts by mass per 100 parts by mass of the diene-based elastomer (B). When the amount of the filler is within this range, the fuel economy performance, moldability, abrasion resistance, and gripping properties of the rubber composition can be further improved. From the same viewpoint, the content of the filler is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more, and is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less, per 100 parts by mass of the diene-based elastomer (B).

[0106] Furthermore, when silica is used as the filler, the content of the silica, relative to 100 parts by mass of the diene-based elastomer (B), from the viewpoint of improving fuel economy and ice gripping performance of a tire partially using the rubber composition for tire treads, is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more, still more preferably 35 parts by mass or more, still more preferably 40 parts by mass or more, still more preferably 45 parts by mass or more, and is preferably 115 parts by mass or less, more preferably 90 parts by mass or less, still more preferably 80 parts by mass or less, still more preferably 75 parts by mass or less, still more preferably 70 parts by mass or less, and still more preferably 65 parts by mass or less.

[0107] Furthermore, when carbon black is used as the filler, the content of the carbon black is, from the viewpoint of improving the fuel economy performance, abrasion resistance, and gripping properties of the rubber composition, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more, and is preferably 75 parts by mass or less, more preferably 65 parts by mass or less, still more preferably 55 parts by mass or less, still more preferably 45 parts by mass or less, still more preferably 40 parts by mass or less, and still more preferably 35 parts by mass or less, relative to 100 parts by mass of the diene elastomer (B).

[0108] Silane Coupling Agent The rubber composition of the present embodiment may further contain a silane coupling agent, such as a sulfide compound, a mercapto compound, a vinyl compound, an amino compound, a glycidoxy compound, a nitro compound, or a chloro compound.

[0109] Examples of the sulfide compounds include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, and 3-trimethoxysilylpropyl. Examples of such tetrasulfides include silylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide.

[0110] Examples of the mercapto-based compounds include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane.

[0111] Examples of the vinyl-based compound include vinyltriethoxysilane and vinyltrimethoxysilane.

[0112] Examples of the amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.

[0113] Examples of the glycidoxy compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane.

[0114] Examples of the nitro-based compounds include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.

[0115] Examples of the chloro-based compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane.

[0116] These silane coupling agents may be used alone or in combination of two or more. Among them, sulfur-containing silane coupling agents such as sulfide compounds and mercapto compounds are preferred from the viewpoint of a large reinforcing effect.

[0117] When the rubber composition of the present embodiment contains a silane coupling agent, the content thereof is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 15 parts by mass, per 100 parts by mass of the diene elastomer (B). When the amount of the silane coupling agent is within the above range, the abrasion resistance of the rubber composition is improved.

[0118] Vulcanizing Agent The rubber composition of this embodiment preferably contains a vulcanizing agent. Examples of vulcanizing agents include sulfur and sulfur compounds. These may be used alone or in combination of two or more. When the rubber composition of this embodiment contains a vulcanizing agent, the content thereof is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.8 to 5 parts by mass per 100 parts by mass of the diene elastomer (B).

[0119] Vulcanization Accelerator The rubber composition of this embodiment may contain a vulcanization accelerator. Examples of the vulcanization accelerator include guanidine-based compounds, sulfenamide-based compounds, thiazole-based compounds, thiuram-based compounds, thiourea-based compounds, dithiocarbamic acid-based compounds, aldehyde-amine-based compounds, aldehyde-ammonia-based compounds, imidazoline-based compounds, and xanthate-based compounds. These may be used alone or in combination of two or more. When the rubber composition of this embodiment contains a vulcanization accelerator, the content thereof is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the diene-based elastomer (B).

[0120] Vulcanization Aid The rubber composition of this embodiment may contain a vulcanization aid. Examples of the vulcanization aid include fatty acids such as stearic acid, metal oxides such as zinc oxide, and fatty acid metal salts such as zinc stearate. These may be used alone or in combination of two or more. When the rubber composition of this embodiment contains a vulcanization aid, the content thereof is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the diene elastomer (B).

[0121] Others The rubber composition may contain, as needed, softeners such as silicone oil, aromatic oil, treated distilled aromatic extracts (TDAE), mild extracted solvates (MES), residual aromatic extracts (RAE), process oil such as paraffin oil or naphthenic oil, resin components such as aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, C9 resins, rosin resins, coumarone-indene resins or phenolic resins, or liquid polymers such as low-molecular-weight polybutadiene, low-molecular-weight polyisoprene, low-molecular-weight styrene-butadiene polymers or low-molecular-weight styrene-isoprene polymers, for the purpose of improving processability, fluidity, and the like.

[0122] When the process oil, resin component, or liquid polymer is contained as a softener, the content thereof is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the diene elastomer (B), from the viewpoint of bleeding resistance.

[0123] Furthermore, the rubber composition of the present embodiment may contain one or more additives such as antioxidants, antioxidants, waxes, lubricants, light stabilizers, scorch inhibitors, processing aids, colorants such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, ultraviolet absorbers, release agents, foaming agents, antibacterial agents, antifungal agents, and fragrances, for the purpose of improving weather resistance, heat resistance, oxidation resistance, and the like.

[0124] Examples of the antioxidant include hindered phenol compounds, phosphorus compounds, lactone compounds, and hydroxyl compounds.

[0125] Examples of the antioxidant include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, and phosphorus compounds.

[0126] The rubber composition of this embodiment may contain a crosslinking agent in addition to the vulcanizing agent. Examples of crosslinking agents include oxygen, organic peroxides, phenolic resins, amino resins, quinone and quinone dioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides, organometallic halides, and silane compounds. These may be used alone or in combination of two or more. The amount of crosslinking agent is preferably 0.1 to 10 parts by mass per 100 parts by mass of the diene elastomer (B).

[0127] <Method for producing rubber composition for tire tread> There are no limitations on the method for producing the rubber composition for tire tread, as long as the components can be mixed uniformly. Examples of methods for uniformly mixing include tangential or intermeshing internal mixers such as kneader-ruders, Brabenders, Banbury mixers, and internal mixers, single-screw extruders, twin-screw extruders, mixing rolls, and rollers, and the mixing can usually be carried out at a temperature in the range of 30 to 270°C.

[0128] The rubber composition for tire treads is preferably vulcanized to be used as a vulcanized rubber. While there are no particular limitations on the conditions and method of vulcanization, it is preferable to carry out the vulcanization using a vulcanization mold under conditions of a vulcanization temperature of 120 to 200°C and a vulcanization pressure of 0.5 to 20 MPa. The polyphenylene ether (A) containing the phenol-derived repeating unit of formula (1) has multiple reaction points with the diene elastomer (B) on side chains projecting outward from the molecular main chain during vulcanization, resulting in little steric hindrance and a high frequency of molecular collisions, resulting in high crosslinking reactivity.

[0129] <Method of Using Polyphenylene Ether> In the method of using polyphenylene ether of this embodiment, a polyphenylene ether having a glass transition temperature of −100° C. or higher and lower than 0° C. as measured by differential scanning calorimetry (DSC) is used as a raw material for a tire composition. As described above, by using a polyphenylene ether having a glass transition temperature of −100° C. or higher and lower than 0° C. as measured by differential scanning calorimetry (DSC) in a rubber composition, a rubber composition can be obtained that exhibits high levels of processability, fuel economy, wet grip performance, and ice grip performance. The configuration of the polyphenylene ether is the same as that described in the rubber composition of the present invention.

[0130] The rubber composition of this embodiment is preferably applied to automobile parts, and more preferably to tire components. Specifically, it can be suitably used for at least one of the following components: tread, sidewall, shoulder, carcass, belt, bead, rim cushion, run-flat reinforcing liner, and other reinforcing rubber components. When the rubber composition of this embodiment is used for a tire tread, for example, it is extruded into the shape of the tire tread while still unvulcanized, and then bonded together in a tire building machine by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in the vulcanizer to obtain a tire. Note that in this embodiment, the tire refers to a pneumatic tire, which can be used for passenger cars, trucks, buses, heavy machinery, etc.

[0131] Hereinafter, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to the following examples.

[0132] The methods for measuring the various physical properties of polyphenylene ether are described below. (1) Number-average molecular weight and weight-average molecular weight of polyphenylene ether A gel permeation chromatograph (LC-2030C Plus, manufactured by Shimadzu Corporation) was used as the measuring device. A calibration curve was prepared using standard polystyrene and ethylbenzene, and the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the resulting modified polyphenylene ether were measured using this calibration curve. The standard polystyrenes used had molecular weights of 3,650,000, 2,170,000, 1,090,000, 681,000, 204,000, 52,000, 30,200, 13,800, 3,360, 1,300, and 550. Two K-805L columns manufactured by Showa Denko K.K. connected in series were used. Chloroform was used as the solvent, and measurements were performed at a solvent flow rate of 1.0 mL / min and a column temperature of 40°C. A 1 g / L chloroform solution of polyphenylene ether was prepared and used as the measurement sample. The UV wavelength of the detection unit was 254 nm for standard polystyrene and 283 nm for polyphenylene ether. The number average molecular weight and weight average molecular weight were calculated from the peak area ratio based on the molecular weight distribution curve obtained by GPC based on the above measurement data.

[0133] (2) Measurement of Glass Transition Temperature The glass transition temperature of polyphenylene ether was measured using a differential scanning calorimeter DSC250 (TA Instruments). In a nitrogen atmosphere, the sample was heated from −120 to 250° C. at a temperature increase rate of 10° C. per minute, then cooled to −120° C. at a temperature increase rate of 20° C. per minute, and the glass transition temperature was then measured at a temperature increase rate of 10° C. per minute.

[0134] (3) Viscosity Measurement at 80°C The viscosity of polyphenylene ether at 80°C was measured using an EMS viscometer (EMS-1000S, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) under the following conditions: a spherical probe of φ4.7 mm, a motor rotation speed of 1,000 rpm, and a measurement time of 5 minutes. The results were evaluated according to the following criteria: ○: Viscosity at 80°C is less than 500,000 cP; △: Viscosity at 80°C is 500,000 cP or more but less than 1,000,000 cP; ×: Viscosity at 80°C is 1,000,000 cP or more, or unmelted.

[0135] (4) Measurement of residual solvent amount (PPE-4) 1 g of polyphenylene ether was dissolved in 5 g of chloroform and solidified with 5 g of methanol. 1 μL of the solution after removing the solid content was measured by gas chromatography (Shimadzu Corporation: GC-2010 Plus) to measure the residual solvent amount.

[0136] (5) Measurement of Residual Catalyst Amount (PPE-4) 30 g of n-butanol was added to 3 g of polyphenylene ether to disperse the polyphenylene ether. 30 g of toluene was further added to dissolve the polyphenylene ether. 10 g of 1N-HCl was added, and the mixture was vigorously stirred at 40°C for 10 minutes, then allowed to stand and the aqueous layer was recovered. 10 g of 1N-HCl was again added to the organic layer, and the mixture was vigorously stirred again at 40°C for 10 minutes, then allowed to stand and the aqueous layer was recovered. The two aqueous layers were combined and weighed, and the amount of residual copper was measured using an atomic absorption spectrophotometer (Shimadzu Corporation AA-7800). (6) Measurement of Residual Amine Amount (PPE-4) 1 g of polyphenylene ether was dissolved in 5 g of chloroform and solidified with 5 g of methanol. 1 μL of the solution from which the solid content had been removed was measured by gas chromatography (GC-2010 Plus, manufactured by Shimadzu Corporation) to determine the amount of residual amine.

[0137] (7) Measurement of Residual Monomer Amount (PPE-4) 0.5 g of polyphenylene ether was diluted to 10 ml with chloroform and solidified with 10 ml of acetonitrile. The solution obtained by removing the solids was used. A high-performance liquid chromatograph (Extrema, manufactured by JASCO Corporation) was used as the measuring device. A Waters XBridge BEH C18 Column, 130 Å, 5 μm, 4.6 mm x 150 mm, 1 / pk was used as the column. The mobile phase used was 0.1 vol% formic acid-acetonitrile, and the solvent flow rate was 0.5 ml / min. The column temperature was 40°C. The UV wavelength of the detector was 280 nm. Based on the above measurement data, the amount of residual monomer was calculated from the peak area obtained by high-performance liquid chromatography.

[0138] <Synthesis of Polyphenylene Ethers (PPE-1 to PPE9)> In the examples and comparative examples described below, polyphenylene ethers (PPE-1 to PPE9) obtained as follows were used.

[0139] (Synthesis of Modified Cardanol) Cardanol obtained from CNSL (product name NX-2026, manufactured by Cardolite, 345 g) and p-toluenesulfonic acid monohydrate (5.9 g) were sequentially added to a 1 L flask connected to a Dewar condenser at -10°C, and the mixture was stirred with a stirring blade. The mixture was then heated to an external temperature of 80°C using an aluminum block heater. Isobutene (100 g) was gradually introduced over 10 hours. The supply of isobutene was stopped, and stirring was continued at 80°C for 15 hours. The temperature of the reaction solution was lowered to 40°C, and toluene (300 g) was added to the reaction solution. Furthermore, a 5% aqueous sodium hydroxide solution (27 g) was added dropwise. Ion-exchanged water (320 g) was added, and the temperature of the reaction solution was raised to 70°C. After stirring for 30 minutes, the organic layer was recovered using a separatory funnel. Ion-exchanged water (760 g) was added to the recovered organic layer, and the temperature of the reaction solution was raised to 70°C. After stirring for 30 minutes, the mixture was allowed to stand. The organic layer was recovered using a separatory funnel. The washed organic layer was concentrated using a rotary evaporator to obtain a pale yellow oily modified cardanol (370 g). The structure of the obtained compound was identified as follows: １ The analysis was carried out by H-NMR. As a result, it was found that the main component was cardanol in which a tert-butyl group was introduced at the 2-position of the cardanol raw material before the reaction. Cardanol raw material: １ H-NMR (CDCl ３ ) δ 7.15-7.10 (m, 1H), 6.78-6.73 (m, 1H), 6.68-6.62 (m, 2H), 5.88-5.77 (m, 0.37H), 5.50-5.29 (m, 3.44H), 5.10-4.95 (m, 0.80H), 4.81-4.64 ( m, 1H), 2.88-2.75 (m, 2.14H), 2.55 (t, 2.13H), 2.08-1.98 (m, 3.31H), 1.69-1.53 ​​(m, 3.15H), 1.51-1.12 (m, 14.10H), 0.94-0.85 (m, 1.95H) Modified cardanol (product): １ H-NMR (CDCl３ ) δ 7.16 (d, 1H), 6.69 (dd, 1H), 6.49 (d, 1H), 5.88-5.77 (m, 0.39H), 5.50-5.29 (m, 3.56H), 5.10-4.95 (m, 0.80H), 4.64 (s, 1H), 2.87-2.75 (m , 2.12H), 2.56-2.46 (m, 2.22H), 2.12-1.95 (m, 3.60), 1.65-1.53 ​​(m, 2.62H), 1.43-1.24 (m, 23.42H), 0.96-0.80 (m, 2.20H)

[0140] (Synthesis of Polyphenylene Ether 1 (PPE-1)) A 1.5-liter jacketed reactor equipped with a line for introducing nitrogen gas at the top of the reactor, a sparger for introducing an oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor was charged with a previously prepared mixture of 0.064 g of cuprous oxide and 0.482 g of 47% hydrogen bromide, 0.154 g of N,N'-di-t-butylethylenediamine, 2.28 g of dimethyl-n-butylamine, 0.748 g of di-n-butylamine, 80.0 g of modified cardanol, 0.05 g of methyltri-n-octylammonium chloride, and 716 g of toluene while flowing nitrogen gas at a rate of 1.24 L / min. Next, air was introduced into the reactor from the sparger at a rate of 0.84 L / min with vigorously stirring. The polymerization temperature was adjusted to 35°C by passing a heat medium through the jacket. 120 minutes after the start of air introduction, the air flow was stopped, and the reactor was purged with nitrogen gas. Then, 0.689 g of ethylenediaminetetraacetic acid tetrasodium salt tetrahydrate (a reagent manufactured by Dojindo Laboratories) was added as an aqueous solution in 80.0 g of water. The mixture was heated to 70°C, and copper extraction was carried out at 70°C for 2 hours. The mixture was then separated by standing to separate into a polyphenylene ether solution (organic phase) and an aqueous phase containing the catalyst metal. The solvent from the organic phase was removed using a rotary evaporator. The resulting liquid polyphenylene ether was subjected to various measurements using the methods described above. The analytical results are shown in Table 1.

[0141] (Synthesis of Polyphenylene Ether 2 (PPE-2)) A 1.5-liter jacketed reactor equipped with a line for introducing nitrogen gas at the top of the reactor, a sparger for introducing an oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor was charged with a previously prepared mixture of 0.074 g of cuprous oxide and 0.555 g of 47% hydrogen bromide, 0.178 g of N,N'-di-t-butylethylenediamine, 2.62 g of dimethyl-n-butylamine, 0.861 g of di-n-butylamine, 6.31 g of 2,6-dimethylphenol, 73.7 g of modified cardanol, 0.05 g of methyltri-n-octylammonium chloride, and 716 g of toluene while flowing nitrogen gas at a rate of 1.24 L / min. Then, air was introduced into the reactor from the sparger at a rate of 0.84 L / min with vigorously stirring. The polymerization temperature was adjusted to 35°C by passing a heat medium through the jacket. 120 minutes after the start of air introduction, the air flow was stopped, and the reactor was purged with nitrogen gas. Then, 0.794 g of ethylenediaminetetraacetic acid tetrasodium salt tetrahydrate (a reagent manufactured by Dojindo Laboratories) was added as an aqueous solution in 80.0 g of water. The mixture was heated to 70°C, and copper extraction was carried out at 70°C for 2 hours. The mixture was then separated by standing to separate into a polyphenylene ether solution (organic phase) and an aqueous phase containing the catalyst metal. The solvent from the organic phase was removed using a rotary evaporator. The resulting liquid polyphenylene ether was subjected to various measurements using the methods described above. The analytical results are shown in Table 1.

[0142] (Synthesis of Polyphenylene Ether 3 (PPE-3)) A 1.0-liter jacketed reactor equipped with a line for introducing nitrogen gas at the top of the reactor, a sparger for introducing an oxygen-containing gas at the bottom of the reactor, stirring turbine blades and a baffle, and a reflux condenser on the vent gas line at the top of the reactor, was charged with a previously prepared mixture of 0.068 g of cuprous oxide and 0.511 g of 47% hydrogen bromide, 0.164 g of N,N'-di-t-butylethylenediamine, 2.41 g of dimethyl-n-butylamine, 0.793 g of di-n-butylamine, 43.8 g of 2,6-dimethylphenol, 31.2 g of 4,6-bis(octylthiomethyl)-o-cresol, 0.05 g of methyltri-n-octylammonium chloride, and 421 g of toluene while flowing nitrogen gas at a rate of 1.16 L / min. Next, air was introduced into the reactor through the sparger at a rate of 0.79 L / min while stirring vigorously. The polymerization temperature was maintained at 40°C by passing a heat medium through the jacket. 120 minutes after the start of air introduction, the air flow was stopped, and the reactor was purged with nitrogen gas. Then, 0.73 g of ethylenediaminetetraacetic acid tetrasodium salt tetrahydrate (a reagent manufactured by Dojindo Laboratories) was added as an aqueous solution in 50.0 g of water. The mixture was heated to 70°C, and copper extraction was carried out at 70°C for 2 hours. The mixture was then separated into a polyphenylene ether solution (organic phase) and an aqueous phase containing the catalyst metal by static separation. The solvent from the organic phase was removed using a rotary evaporator. The resulting liquid polyphenylene ether was subjected to various measurements using the methods described above. The analytical results are shown in Table 1.

[0143] (Synthesis of Polyphenylene Ether 4 (PPE-4)) Liquid polyphenylene ether was obtained under the same conditions as in Production Example 3, except that 10.2 g of 2,6-dimethylphenol and 69.8 g of modified cardanol were used. The obtained liquid polyphenylene ether was subjected to the respective measurements by the methods described above. The results of the analyses are shown in Table 1. The residual solvent amount was 0.084 mass%, the residual catalyst amount was 0.02 ppm, the residual amine amount was 300 ppm, and the residual monomer amount was 1.5 mass%.

[0144] (Synthesis of Polyphenylene Ether 5 (PPE-5)) A liquid polyphenylene ether was obtained under the same conditions as in Production Example 3, except that 27.1 g of 2,6-dimethylphenol and 52.9 g of modified cardanol were used. The obtained liquid polyphenylene ether was subjected to the various measurements by the methods described above. The analytical results are shown in Table 1.

[0145] (Synthesis of Polyphenylene Ether 6 (PPE-6)) A dry polyphenylene ether was obtained in the same manner as in Production Example 6, except that 80.0 g of 2,6-dimethylphenol was used. The obtained polyphenylene ether was subjected to the respective measurements by the methods described above. The respective analytical results are shown in Table 1.

[0146] (Synthesis of polyphenylene ether 7 (PPE-7)) Poly(2,6-dimethyl-1,4-phenylene ether): Noryl ＴＭ SA120 (Sabic), number average molecular weight (Mn) = 2350 g / mol

[0147] (Synthesis of polyphenylene ether 8 (PPE-8)) Poly(2,6-dimethyl-1,4-phenylene ether): Xyron ＴＭ S201A (manufactured by Asahi Kasei Corporation), number average molecular weight (Mn) = 19,000 g / mol

[0148] (Synthesis of Polyphenylene Ether 9 (PPE-9)) Poly(2,6-dimethyl-1,4-phenylene ether): Noryl ＴＭ SA90 (Sabic), number average molecular weight (Mn) = 1800 g / mol

[0149] (Synthesis of Polyphenylene Ether 10 (PPE-10)) 1 kg of Noryl ＴＭ SA120 (PPE, manufactured by Sabic) was mixed with 3 kg of toluene at 60°C. The mixture was stirred until the PPE was completely dissolved. 20 kg of methanol was then added, and the mixture was stirred for 30 minutes for homogenization. The suspension was cooled to room temperature, the precipitate was separated from the supernatant, and the solvent was removed. The recovered product was a powder with an Mn of 950 g / mol.

[0150] (Synthesis of Polyphenylene Ether 11 (PPE-11)) 1 kg of Noryl ＴＭ SA90 (PPE, manufactured by Sabic) was mixed with 3 kg of toluene at 60°C. The mixture was stirred until the PPE was completely dissolved. 42.8 kg of methanol was then added, and the mixture was stirred for 30 minutes for homogenization. The suspension was cooled to room temperature, the precipitate was separated from the supernatant, and the solvent was removed. The recovered product was a powder with an Mn of 950 g / mol.

[0151]

[0152] Examples 1 to 16, Comparative Examples 1 to 7: Rubber composition samples were prepared by mixing the components according to the formulation shown in Table 2 below using the materials and methods described below. The components other than the polyphenylene ether (A) were uniformly formulated as shown below. The components constituting the rubber composition were kneaded using an internal mixer (capacity: 0.5 L) equipped with a temperature control device. In the first stage of mixing, materials other than sulfur and vulcanization accelerator were kneaded at a filling rate of 65% and a rotor rotation speed of 50 to 90 rpm. The temperature of the internal mixer was controlled, and the compound was obtained at a discharge temperature of 150 to 160°C. Next, in the second stage of mixing, the compound obtained above was cooled to room temperature and then kneaded again to improve dispersion of the reinforcing filler. Again, the discharge temperature of the compound was adjusted to 150 to 160°C by controlling the temperature of the mixer. After cooling, in the third stage of kneading, a vulcanization accelerator and sulfur were added and kneaded using an open roll set at 70°C to obtain an unvulcanized rubber composition. The mixture was then molded and vulcanized in a vulcanization press at 160°C for a predetermined vulcanization time to obtain a vulcanized rubber composition. The vulcanization time was set to 90% vulcanization time of the unvulcanized rubber composition plus 5 minutes.

[0153] (Polyphenylene Ether (A)) Using PPE1 to PPE9 obtained above and shown in Table 1, the type and compounding amount were changed and mixed into a rubber composition.

[0154] (Diene-based elastomer (B)) Styrene-butadiene rubber (SBR (HS265 manufactured by Asahi Kasei Corporation): 70 parts by mass) Butadiene rubber (BR (trade name "U150" manufactured by Ube Industries, Ltd.): 30 parts by mass)

[0155] (Other components) Silica (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m ２ / g): 5 parts by mass, 15.0 parts by mass, 50.0 parts by mass, 75.0 parts by mass, 100.0 parts by mass, 120.0 parts by mass Silane coupling agent (manufactured by Evonik Degussa, "Si75", bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass Carbon black (manufactured by Tokai Carbon Co., Ltd., Seest KH (N339)): 5.0 parts by mass Softener (TDAE oil (manufactured by H&R, trade name "V500")): 32 parts by mass Zinc oxide: 2.5 parts by mass Stearic acid: 2.0 parts by mass Wax, Sunnock: 1.5 parts by mass Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass Sulfur: 2.2 parts by mass Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide): 1.7 parts by mass Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass

[0156] <Evaluation> The rubber composition and vulcanized rubber composition samples obtained were evaluated as follows. The evaluation results are shown in Table 2. (1) Hardness For the vulcanized rubber composition samples obtained in the Examples and Comparative Examples, the durometer type A values ​​were measured in accordance with JIS K6253.

[0157] (2) Tensile Strength and Elongation at Break The tensile strength and elongation at break of the samples of the vulcanized rubber compositions obtained in the Examples and Comparative Examples were measured in accordance with the tensile test method of JIS K6251.

[0158] (3) Processability (Mooney viscosity (ML viscosity) of rubber composition) Using the unvulcanized rubber composition sample obtained above as a specimen, a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) was used in accordance with ISO 289. After preheating at 130°C for 1 minute, the rotor was rotated at 2 revolutions per minute for 4 minutes, and the viscosity was measured. Evaluation was made using the following index. ○: ML viscosity less than 100 △: ML viscosity 100 or more but less than 150 ×: ML viscosity 150 or more

[0159] (4) Fuel Economy (tan δ at 50°C) Samples of the vulcanized rubber compositions obtained in the Examples and Comparative Examples were measured for tan δ in torsion mode at 50°C with a frequency of 10 Hz and a strain of 3% using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. The tan δ was used as an index of fuel economy. The value of tan δ was determined using the following index, with a smaller value indicating better fuel economy. ○: tan δ at 50°C is less than 0.120 △: tan δ at 50°C is 0.120 or more but less than 0.130 ×: tan δ at 50°C is 0.130 or more

[0160] (5) Wet Grip Properties (tan δ at 0°C) Samples of the vulcanized rubber compositions obtained in the Examples and Comparative Examples were measured for tan δ at 0°C in a torsion mode at a frequency of 10 Hz and a strain of 1% using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. The tan δ was used as an index of wet grip properties. The tan δ value was determined using the following index, with a larger value indicating better wet grip properties. ○: tan δ at 0°C is 0.180 or more; △: tan δ at 0°C is 0.170 or more and less than 0.180; ×: tan δ at 0°C is less than 0.170.

[0161] (6) Ice gripping property (tan δ at -20°C) Samples of the vulcanized rubber compositions obtained in the examples and comparative examples were measured for tan δ in torsion mode at -20°C with a frequency of 10 Hz and a strain of 1% using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. The tan δ was used as an index of ice gripping property. The tan δ value was determined using the following index, with a higher value indicating better ice gripping property. ○: tan δ at -20°C is 0.302 or more △: tan δ at -20°C is 0.275 or more and less than 0.302 ×: tan δ at -20°C is less than 0.275

[0162] (7) Vulcanization Rate The rubber composition obtained above was measured for a vulcanization curve at a temperature of 160°C using a rotorless vulcanization tester in accordance with JIS K6300-2 "Method for determining vulcanization characteristics using a vibration vulcanization tester," with the obtained torque on the vertical axis and vulcanization time on the horizontal axis. In the obtained vulcanization curve, the vulcanization time required from the start of vulcanization until the torque reached the maximum value MH was defined as tc (max). According to the provisions of JIS K6300-2, the difference between the minimum torque ML and the maximum torque MH was defined as ME (ME = MH - ML), and the vulcanization time from the start of the test until the torque reached ML + 90% ME was defined as T90 (unit: minutes), which was measured as the vulcanization rate.

[0163] (8) Performance Balance In consideration of the fuel economy (tan δ at 50°C), wet grip performance (tan δ at 0°C), and ice grip performance (tan δ at -20°C) of the vulcanized rubber composition samples obtained in the Examples and Comparative Examples, the performance balance was judged using the following index: ○: ○ in all of fuel economy, wet grip, and ice grip performance △: △ in any of fuel economy, wet grip, and ice grip performance ×: × in any of fuel economy, wet grip, and ice grip performance

[0164]

[0165] From Table 2, it was found that Examples 1 to 16 were excellent in hardness, tensile strength, elongation at break, processability, fuel economy, wet grip performance, ice grip performance, and vulcanization speed, and that the balance of these properties was good. It was also found that Comparative Examples 1 to 7 were inferior to the Examples in any one of hardness, tensile strength, elongation at break, processability, fuel economy, wet grip performance, ice grip performance, and vulcanization speed, or in the balance thereof.

[0166] The rubber composition of the present embodiment is industrially applicable as a material for tires such as truck tires, bus tires, car tires, motorcycle tires, off-road tires, and aircraft tires; materials for tire components such as treads, sidewalls, chafer strips, tire rubber layers, reinforcing cord coating materials, and cushion layers; industrial parts such as fibers, thin films, laminates, automobile parts, and medical parts; molded articles such as equipment housings, consumer products, and packaging; tire curing bladders, inner tubes, air sleeves, hoses, belts such as conveyor belts and automobile belts, solid tires, tires for retreading, footwear components, rollers for graphic arts applications, vibration isolators, pharmaceutical equipment, adhesives, caulking materials, sealants, glazing compounds, protective coatings, air cushions, air springs, air bellows, accumulator bags, and materials for various bladders for liquid storage and curing methods, automobile suspension bumpers, automobile exhaust pipe hangers, and molded rubber parts such as body mounts.

Claims

1. A rubber composition comprising: a polyphenylene ether (A) having a glass transition temperature of -100°C or higher and lower than 0°C as measured by differential scanning calorimetry (DSC); and a diene-based elastomer (B).

2. The rubber composition according to claim 1, wherein the polyphenylene ether (A) comprises a repeating unit derived from a phenol of the following formula (1) and a repeating unit derived from a phenol of the following formula (2), and the content of the repeating unit derived from the phenol of the following formula (1) is 31 mol% or more and 100 mol%, and the content of the repeating unit derived from the phenol of the following formula (2) is more than 0 mol% and 69 mol% or less, relative to 100 mol% of the total of the repeating units of the following formulas (1) and (2). (In formula (1), R １３ represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms; R １１ and R １２ are each independently any one of a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, and a substituent represented by the following formula (3): (In formula (3), R ３１ each independently form a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R ３１ The atoms in R are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms. ３２ each independently represents an optionally substituted alkylene group having 1 to 8 carbon atoms; each b independently represents 0 or 1; R ３３ is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group. (In formula (2), R ２１ are each independently an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R ２２ are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.

3. The rubber composition according to claim 1 or 2, wherein the polyphenylene ether (A) has a viscosity at 80° C. of less than 1,000,000 cP.

4. The rubber composition according to claim 1 or 2, wherein the polyphenylene ether (A) has a number average molecular weight of less than 5,500.

5. The rubber composition according to claim 1 or 2, wherein the polyphenylene ether (A) contains a biomass-derived monomer.

6. The rubber composition according to claim 1 or 2, characterized in that the biomass-derived monomer is CNSL.

7. The rubber composition according to claim 1 or 2, characterized in that the polyphenylene ether (A) is contained in an amount of 0.01 to 65 parts by mass per 100 parts by mass of the diene elastomer (B).

8. The rubber composition according to claim 1 or 2, characterized in that it contains 10 to 115 parts by mass of silica per 100 parts by mass of the diene elastomer (B).

9. A method for using polyphenylene ether, comprising using polyphenylene ether having a glass transition temperature of −100° C. or higher and lower than 0° C. as measured by differential scanning calorimetry (DSC) as a raw material for a tire composition.

10. A method for producing vulcanized rubber, comprising the steps of: mixing a diene elastomer (B) with a polyphenylene ether (A) having a glass transition temperature of -100°C or higher and lower than 0°C as measured by differential scanning calorimetry (DSC) to obtain a rubber composition; and vulcanizing the rubber composition, wherein the polyphenylene ether (A) has an unsaturated hydrocarbon group in a side chain, and the diene elastomer (B) and the polyphenylene ether (A) undergo a crosslinking reaction.