Rubber composition for tires and tires

Abstract

To provide a rubber composition for a tire and a tire capable of improving an overall performance of fracture characteristics, crack resistant flexibility and fracture characteristics after thermal degradation.SOLUTION: A rubber composition for a tire includes: a rubber constituent at least containing isoprene rubber, styrene-butadiene rubber and / or butadiene rubber; and a filler. The rubber composition for a tire further includes a resin having, as a monomer: a chemical compound A having a structure with an aromatic ring modified with a hydroxymethyl group; and a chemical compound B having a structure with an aromatic ring modified with a hydroxy group. A content of the isoprene rubber in the rubber constituent 100 mass% is 35 mass% or more.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, various methods for improving the fracture properties of rubber compositions for tires have been studied (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as a result of the study by the present inventor, it has been found that there is room for improvement in the conventional technology in terms of improving the comprehensive performance of fracture properties, crack growth resistance, and fracture properties after heat deterioration. An object of the present invention is to provide a rubber composition for tires and a tire that can solve the above problems and improve the comprehensive performance of fracture properties, crack growth resistance, and fracture properties after heat deterioration.

Means for Solving the Problems

[0005] The present invention relates to a rubber composition for tires containing a rubber component containing at least an isoprene rubber and a styrene-butadiene rubber and / or a butadiene rubber and a filler, including a resin having a compound A with a structure in which an aromatic ring is modified with a hydroxymethyl group and a compound B with a structure in which an aromatic ring is modified with a hydroxy group as monomers, and the content of the isoprene rubber in 100% by mass of the rubber component is 35% by mass or more.

[0006] It is preferable that the content of carbon black in 100% by mass of the filler is 80% by mass or more.

[0007] It is preferable that the content (parts by mass) of the above resin / the content (parts by mass) of the isoprene rubber is ≤ 0.5.

[0008] As the rubber component, it contains butadiene rubber, and it is preferable that the content (parts by mass) of butadiene rubber or styrene - butadiene rubber / the content (parts by mass) of the isoprene rubber is ≥ 0.15.

[0009] It is preferable that the content of the isoprene rubber in 100% by mass of the above rubber component is 80% by mass or less.

[0010] The present invention also relates to a tire having a tire member using the above rubber composition.

Effects of the Invention

[0011] The present invention is a rubber composition for tires containing a rubber component containing at least an isoprene rubber and a styrene - butadiene rubber and / or a butadiene rubber, and a filler, and contains a resin having as monomers a compound A having a structure in which an aromatic ring is modified with a hydroxymethyl group and a compound B having a structure in which an aromatic ring is modified with a hydroxy group. Since the content of the isoprene rubber in 100% by mass of the above rubber component is 35% by mass or more, the comprehensive performance of the fracture characteristics, crack - resistant flexural properties, and fracture characteristics after thermal deterioration can be improved.

Modes for Carrying Out the Invention

[0012] The rubber composition for tires of the present invention is a rubber composition for tires containing a rubber component containing at least an isoprene rubber and a styrene - butadiene rubber (SBR) and / or a butadiene rubber (BR), and a filler, and contains a resin having as monomers a compound A having a structure in which an aromatic ring is modified with a hydroxymethyl group and a compound B having a structure in which an aromatic ring is modified with a hydroxy group, and the content of the isoprene rubber in 100% by mass of the above rubber component is 35% by mass or more.

[0013] The reason why the above - mentioned effects can be obtained with the above rubber composition is presumed as follows. (1) Since the above resin has good compatibility with isoprene rubber, it can enhance the strength and rigidity of the isoprene rubber phase, and improve the fracture properties and crack resistance to bending. (2) By including SBR and / or BR together with isoprene rubber, since the above resin forms domains in the isoprene rubber phase, the fracture properties and crack resistance to bending are further improved, and the fracture properties after thermal deterioration are also improved. (3) By setting the content of isoprene rubber to a specific amount or more, it becomes easier to form a co-continuous structure with SBR·BR / isoprene rubber. As a result, the strength and rigidity of the entire rubber composition can be improved, so that the fracture properties and crack resistance to bending are improved, and the fracture properties after thermal deterioration are also improved, and the comprehensive performance of the fracture properties, crack resistance to bending, and fracture properties after thermal deterioration can be improved.

[0014] <Rubber component> The above rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0015] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, still more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, still more preferably 1,000,000 or less. When it is within the above range, the effect tends to be obtained more favorably.

[0016] In this specification, the weight average molecular weight (Mw) can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0017] The above rubber composition contains at least styrene butadiene rubber (SBR) and / or butadiene rubber (BR) and isoprene rubber as the rubber component.

[0018] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, denatured IR, etc. As NR, for example, those commonly used in the tire industry such as SIR20, RSS#3, TSR20, etc. can be used. IR is not particularly limited, and for example, those commonly used in the tire industry such as IR2200, etc. can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., examples of denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., and examples of denatured IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more. Among them, NR is preferred.

[0019] In 100% by mass of the rubber component, the content of isoprene rubber is 35% by mass or more, preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 60% by mass or less, and particularly preferably 50% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0020] BR is not particularly limited, and BR having a high cis content, BR having a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. Commercially available products include those of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. These may be used alone or in combination of two or more.

[0021] The cis amount (cis content) of BR is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, most preferably 90% by mass or more, and even most preferably 95% by mass or more, and the upper limit is not particularly limited. When within the above range, the effect tends to be obtained more favorably. Note that the cis amount of BR can be measured by infrared absorption spectroscopy.

[0022] In 100% by mass of the rubber component, the content of BR is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, particularly preferably 50% by mass or more, and is preferably 65% by mass or less, more preferably 60% by mass or less. When within the above range, the effects tend to be obtained more favorably.

[0023] SBR is not particularly limited. For example, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization styrene-butadiene rubber (S-SBR), etc. can be used. Examples of commercially available products include products of Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. These may be used alone or in combination of two or more.

[0024] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, particularly preferably 20% by mass or more. Also, the styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less, particularly preferably 30% by mass or less. When within the above range, the effects tend to be obtained more favorably. In this specification, the styrene content of SBR 1 is calculated by 1H-NMR measurement.

[0025] In 100% by mass of the rubber component, the content of SBR is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, particularly preferably 50% by mass or more, and is preferably 65% by mass or less, more preferably 60% by mass or less. When within the above range, the effects tend to be obtained more favorably.

[0026] In the above rubber composition, as the rubber component, it preferably contains BR, and further, the content (parts by mass) of BR or SBR / the content (parts by mass) of isoprene rubber ≧ 0.15. Thereby, the above resin is more likely to form domains in the isoprene rubber phase, and the fracture properties and crack resistance to bending are improved, and the fracture properties after thermal deterioration also tend to be improved.

[0027] The content (parts by mass) of BR or SBR / the content (parts by mass) of isoprene rubber is preferably 0.15 or more, more preferably 0.30 or more, still more preferably 0.50 or more, particularly preferably 0.70 or more, most preferably 0.90 or more, even most preferably 1.10 or more, still most preferably 1.20 or more, and particularly most preferably 1.40 or more. Also, it is preferably 2.50 or less, more preferably 2.25 or less, still more preferably 2.00 or less, particularly preferably 1.90 or less, most preferably 1.80 or less, and even most preferably 1.70 or less. When within the above range, the effect tends to be obtained more favorably. In this relationship, the content of BR, the content of SBR, and the content of isoprene rubber are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

[0028] In 100% by mass of the rubber component, the total content of isoprene rubber and BR is preferably 40% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass. When within the above range, the effect tends to be obtained more favorably.

[0029] In 100% by mass of the rubber component, the total content of isoprene rubber and SBR is preferably 40% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass. When within the above range, the effect tends to be obtained more favorably.

[0030] Examples of rubber components that can be used in addition to isoprene rubber, BR, and SBR include diene rubbers such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more.

[0031] The rubber component may have a functional group introduced therein that interacts with a filler such as silica by modification. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have substituents. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0032] Specific examples of the compound (modifying agent) having the functional group include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc.

[0033] <Resin> The rubber composition contains a resin having as monomers a compound A having a structure in which an aromatic ring is modified with a hydroxymethyl group and a compound B having a structure in which an aromatic ring is modified with a hydroxyl group. The resin may be used alone or in combination of two or more.

[0034] <<Compound A>> First, compound A will be described. Compound A is a compound having a structure in which an aromatic ring is modified with a hydroxymethyl group. Compound A may be used alone or in combination of two or more. As compound A, it preferably is an aromatic compound containing at least one aromatic ring having at least two functional groups, one of these functional groups being a hydroxymethyl group and the other being an aldehyde group or a hydroxymethyl group, and more preferably is a compound represented by the following general formula (A). In the present specification, compound A may sometimes also be referred to as an aromatic compound. [Chemical formula] (In the formula, Ar represents an aromatic ring, and A represents CHO (aldehyde group) or CH 2 OH (hydroxymethyl group)).

[0035] The above aromatic ring is preferably a 5- or 6-membered ring, and more preferably a 5-membered ring. Further, the above aromatic ring may contain carbon atoms as the ring members and may also contain one or more heteroatoms, particularly nitrogen, oxygen or sulfur atoms, which may be oxidized in the form of N-oxide or S-oxide. Among them, the above aromatic ring preferably contains carbon atoms as the ring members and one heteroatom, particularly nitrogen, oxygen or sulfur atom, and more preferably contains carbon atoms as the ring members and one oxygen atom.

[0036] The above aromatic ring contains 0, 1 or 2 heteroatoms. The remainder of the above aromatic ring may or may not be substituted. The above aromatic ring can have 0, 1 or 2 aldehyde groups, preferably 0 or 1 aldehyde group. The above aromatic ring can have 1, 2 or 3 hydroxymethyl groups, preferably 1 or 2 hydroxymethyl groups. Furthermore, the above aromatic ring can also have 0, 1 or 2 other functional groups, particularly a hydroxy group.

[0037] In an embodiment where the aromatic ring is a 6-membered ring, the A and hydroxymethyl groups are preferably in the meta or para positions relative to each other. In an embodiment where the aromatic ring is a 5-membered ring, the ring can contain one or more heteroatoms, particularly nitrogen, oxygen, or sulfur atoms, which may be oxidized in the form of an N-oxide or S-oxide. The aromatic ring preferably contains 1 or 2 heteroatoms, preferably 1 heteroatom.

[0038] When the aromatic ring is a 5-membered ring, it is preferable that at least one of the following three conditions is satisfied, more preferably that at least two of the following three conditions are satisfied, and even more preferably that all of the following three conditions are satisfied. - The aromatic ring contains 0 or 1 aldehyde group; - The aromatic ring contains 1 or 2 hydroxymethyl groups; - Apart from the aldehyde group and hydroxymethyl group, the remainder of the aromatic ring has no substituents.

[0039] Compound A is preferably a compound represented by the following general formula (A1), and more preferably a compound represented by the following general formula (A1-1).

Chemical formula

Chemical formula

[0040] In the above general formula (A1) and the above general formula (A1-1), A is preferably CHO, and X is preferably O.

[0041] As compound A, it is preferably a compound represented by the following formula (A1-1a) or a compound represented by the following formula (A1-1b), and more preferably a compound represented by the following formula (A1-1a) (5-(hydroxymethyl)-furfural).

Chemical formula

[0042] As compound A, the above aromatic ring may be a 6-membered ring, may be oxidized in the N-oxide form, and may contain 0, 1 or more heteroatoms, particularly nitrogen. It is preferable that the above A and the hydroxymethyl group are in the meta or para position to each other. The above aromatic ring can have 0, 1 or 2 aldehyde groups, preferably 0 or 1 aldehyde group. The above aromatic ring can have 1, 2 or 3 hydroxymethyl groups, preferably 1 or 2 hydroxymethyl groups. Furthermore, the above aromatic ring can also have 0, 1 or 2 other functional groups, particularly a hydroxy group.

[0043] As compound A, it is also preferable to be a compound represented by the following general formula (A2).

Chemical formula

[0044] R 1 preferably represents hydrogen or a C 1 -C 6 alkyl group.

[0045] The aromatic ring of the compound represented by the general formula (A2) is preferably a benzene ring. The compound represented by the general formula (A2) is more preferably 2-(hydroxymethyl)benzene-1-carboxaldehyde, 3-(hydroxymethyl)benzene-1-carboxaldehyde, 4-(hydroxymethyl)benzene-1-carboxaldehyde, 3-hydroxymethyl-6-hydroxybenzene-1-carboxaldehyde, 3-hydroxymethyl-4-hydroxybenzene-1-carboxaldehyde, 3-hydroxymethyl-2-hydroxybenzene-1-carboxaldehyde, 3-hydroxymethyl-2-hydroxybenzene-1,5-dicarboxaldehyde, 5-hydroxymethyl-2-hydroxybenzene-1,3-dicarboxaldehyde, 3,5-dihydroxymethyl-4-hydroxybenzene-1-carboxaldehyde, 3,5-hydroxymethyl-2-hydroxybenzene-1-carboxaldehyde, 1,2-dihydroxymethylbenzene, 1,3-dihydroxymethylbenzene, 1,4-dihydroxymethylbenzene, 1,3-dihydroxymethyl-6-hydroxybenzene, 1,3-dihydroxymethyl-4-hydroxybenzene, 1,3-dihydroxymethyl-2-hydroxybenzene, 1,3,5-trihydroxymethyl-2-hydroxybenzene, 1,3-dihydroxymethyl-6-hydroxybenzene, 1,3,5-trihydroxymethyl-4-hydroxybenzene, 1,3,2-trihydroxymethyl-2-hydroxybenzene, and mixtures of these compounds.

[0046] Compound A is also preferably 1-(hydroxymethyl)benzene-4-carboxaldehyde of formula (A2a) or 1,4-dihydroxymethylbenzene of formula (A2b).

Chemical formula

[0047] In addition, in the present specification, Compound A is a compound having a structure in which an aromatic ring is modified with a hydroxymethyl group. However, compounds having a structure in which an aromatic ring is modified with a hydroxymethyl group include not only compounds having a structure in which an aromatic ring is modified with a hydroxymethyl group, but also compounds derived from a structure in which an aromatic ring is modified with a hydroxymethyl group.

[0048] Examples of the compound derived from a structure in which an aromatic ring is modified with a hydroxymethyl group include compounds obtained by reacting the compound represented by the above general formula (A) with the compound represented by the following general formula (α) and / or the compound represented by the following general formula (β).

Chemical formula

[0049] Examples of the compound obtained by reacting the compound represented by the above general formula (A) (preferably the compound represented by the above general formula (A1), more preferably the compound represented by the above general formula (A1-1)) with the compound represented by the above general formula (α) and / or the compound represented by the above general formula (β) include compounds having the following structures.

Chemical formula

[0050] Compound A is preferably a compound represented by the above general formula (A), more preferably a compound represented by the above general formula (A1), still more preferably a compound represented by the above general formula (A1-1), and particularly preferably a compound represented by the above formula (A1-1a) (5-(hydroxymethyl)-furfural).

[0051] <<Compound B>> Next, Compound B will be described. Compound B is a compound having a structure in which an aromatic ring is modified with a hydroxy group. Compound B may be used alone or in combination of two or more. As Compound B, a phenol compound is preferable, an aromatic polyphenol or an aromatic monophenol is more preferable, and an aromatic polyphenol is even more preferable. In this specification, the aromatic polyphenol means an aromatic compound containing at least one aromatic ring (preferably a benzene ring) having more than one hydroxy group. Also, in this specification, the aromatic monophenol means an aromatic compound containing at least one aromatic ring (preferably a benzene ring) having one hydroxy group. Note that in this specification, Compound B may also be referred to as a phenol compound or phenol.

[0052] The aromatic polyphenol preferably contains at least one aromatic ring in which at least two hydroxy groups are in the meta position to each other and the two ortho positions to at least one hydroxy group are unsubstituted. The aromatic monophenol preferably contains at least one 6-membered aromatic ring having a single hydroxy group. For this aromatic monophenol, it is more preferable that the two ortho positions to the above hydroxy group are unsubstituted, or at least one ortho position and the para position to the above hydroxy group are unsubstituted.

[0053] The aromatic polyphenol may be an aromatic polyphenol of one or more aromatic rings, at least one of these aromatic rings, or even each aromatic ring, which has at least two hydroxy groups in the meta position to each other and the two ortho positions to at least one of the above hydroxy groups are unsubstituted, or a simple molecule containing these aromatic rings. Similarly, the aromatic monophenol may be an aromatic monophenol of a simple molecule containing one or more 6-membered aromatic rings having a single hydroxy group, at least one of these 6-membered aromatic rings, or even each 6-membered aromatic ring. It is preferable that the two ortho positions with respect to the above hydroxy group are unsubstituted, or at least one ortho position and the para position with respect to the above hydroxy group are unsubstituted. Such a simple molecule does not contain a repeating unit.

[0054] The aromatic polyphenol may be a precondensed resin based on the following components. - At least one aromatic polyphenol containing at least one aromatic ring having at least two hydroxy groups in the meta position to each other, and the two ortho positions with respect to at least one of the above hydroxy groups are unsubstituted; and - At least one compound capable of reacting with the above polyphenol containing at least one aldehyde group and / or at least one compound capable of reacting with the above polyphenol containing at least two hydroxymethyl groups having an aromatic ring.

[0055] Such a precondensed resin based on an aromatic polyphenol, unlike the above simple molecule, contains a repeating unit. In this case, the above repeating unit contains at least one aromatic ring having at least two hydroxy groups in the meta position to each other.

[0056] Similarly, the aromatic monophenol may be a precondensed resin based on the following components. - At least one aromatic monophenol containing at least one 6-membered aromatic ring having a single hydroxy group - The two ortho positions of the above hydroxy group are unsubstituted, or - At least one ortho position and the para position with respect to the above hydroxy group are unsubstituted; At least one compound capable of reacting with the monophenol containing at least one aldehyde group and / or at least one compound capable of reacting with the monophenol containing at least two hydroxymethyl groups having an aromatic ring.

[0057] Such precondensed resins based on aromatic monophenols, unlike the above simple molecules, contain repeating units. In this case, the repeating units contain at least one six-membered aromatic ring having a single hydroxy group.

[0058] Hereinafter, the aromatic polyphenol and / or the aromatic monophenol are described in their simple molecular form. This aromatic polyphenol and / or this aromatic monophenol can then condense and may partially form the above repeating units.

[0059] <<<Aromatic polyphenol>>> Next, the aromatic polyphenol will be described. The aromatic ring of the above aromatic polyphenol preferably has three hydroxy groups in the meta position to each other. It is preferable that the two ortho positions to each hydroxy group are unsubstituted. More preferably, it has three hydroxy groups in the meta position to each other and the two ortho positions to each hydroxy group are unsubstituted. This means that the two carbon atoms located on both sides (ortho positions) of the hydroxylated carbon atom (i.e., having the above hydroxy group) have simple hydrogen atoms. It is preferable that the remainder of the aromatic ring of the above aromatic polyphenol is unsubstituted. This means that the other carbon atoms of the remainder of the aromatic ring (other than the carbon atoms having the above hydroxy group) have simple hydrogen atoms. The above aromatic polyphenol contains a plurality of aromatic rings, at least two of which each have at least two hydroxy groups at the meta position relative to each other, and it is also preferable that the ortho position to at least one of the hydroxy groups of at least one aromatic ring is unsubstituted.

[0060] It is preferable that at least one of the aromatic rings of the above aromatic polyphenol has three hydroxy groups at the meta position relative to each other. It is preferable that the two ortho positions to each hydroxy group of at least one aromatic ring are unsubstituted. It is preferable that the two ortho positions to each hydroxy group of each aromatic ring are unsubstituted. It is preferable that the remaining part of each aromatic ring is unsubstituted. This means that the other carbon atoms of the remaining part of each aromatic ring (other than those having the above hydroxy group or the carbon atoms having the group bonding the above aromatic rings together) have simple hydrogen atoms. It is preferable that the above aromatic ring having at least two hydroxy groups at the meta position relative to each other and the two ortho positions to at least one of the above hydroxy groups being unsubstituted is a benzene ring. It is preferable that each aromatic ring of the above aromatic polyphenol is a benzene ring.

[0061] Examples of aromatic polyphenols containing only one aromatic ring include, for example, the compound represented by the following formula (B1) (resorcinol), the compound represented by the following formula (B2) (phloroglucinol), etc. Among them, the compound represented by the following formula (B2) (phloroglucinol) is preferable.

Chemical formula

[0062] When the above aromatic polyphenol contains a plurality of aromatic rings, it is preferable that at least two of these aromatic rings are selected from the aromatic rings of the following general formula, whether the same or different.

Chemical formula

[0063] The aromatic polyphenol may be 2,2',4,4'-tetrahydroxydiphenyl sulfide of the following structural formula (B4). [Chemical formula]

[0064] The aromatic polyphenol may be a derivative of 2,2',4,4'-tetrahydroxydiphenyl benzophenone of the following structural formula (B5). [Chemical formula]

[0065] Each of the compounds (B4) and (B5) is an aromatic polyphenol containing two aromatic rings (having formula B3-c), and each of these polyphenols has at least two (in this case two) hydroxy groups in the meta position relative to each other. In the case of an aromatic polyphenol containing at least one aromatic ring according to formula B3-b, the two ortho positions with respect to each hydroxy group of at least one aromatic ring are unsubstituted. In the case of an aromatic polyphenol containing a plurality of aromatic rings according to formula B3-b, the two ortho positions with respect to each hydroxy group of each aromatic ring are unsubstituted.

[0066] Examples of the aromatic polyphenol include resorcinol (B1), phloroglucinol (B2), 2,2',4,4'-tetrahydroxydiphenyl sulfide (B4), 2,2',4,4'-tetrahydroxybenzophenone (B5), and precondensed resins derived from at least one of these phenols. Among them, phloroglucinol is preferred.

[0067] The aromatic polyphenol includes a precondensed resin based on the above aromatic polyphenol. This precondensed resin preferably has the following components as a base. - At least one aromatic polyphenol selected from the group consisting of resorcinol (B1), phloroglucinol (B2), 2,2',4,4'-tetrahydroxydiphenyl sulfide (B4), 2,2',4,4'-tetrahydroxybenzophenone (B5), and mixtures thereof; and - At least one compound capable of reacting with the polyphenol containing at least one aldehyde group, and / or at least one compound capable of reacting with the polyphenol containing at least two hydroxymethyl groups having an aromatic ring.

[0068] A compound capable of reacting with the polyphenol containing at least one aldehyde group and / or a compound capable of reacting with the polyphenol containing at least two hydroxymethyl groups in the aromatic ring may be compound A or any other aldehyde. Preferably, the compound capable of reacting with the polyphenol containing at least one aldehyde group and / or the compound capable of reacting with the polyphenol containing at least two hydroxymethyl groups in the aromatic ring is an aromatic compound containing an aromatic ring having at least two functional groups, one of these functional groups is a hydroxymethyl group, and the other is an aldehyde group or a hydroxymethyl group, and is selected from the group consisting of formaldehyde, benzaldehyde, furfural, 2,5-furandicarboxaldehyde, 1,4-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,2-benzenedicarboxaldehyde and mixtures thereof. More preferably, when the compound is an aromatic compound containing an aromatic ring having at least two functional groups, one of these functional groups is a hydroxymethyl group, and the other is an aldehyde group or a hydroxymethyl group, this compound is selected from the group consisting of 5-(hydroxymethyl)furfural, 2,5-di(hydroxymethyl)furan, and mixtures of these compounds.

[0069] Therefore, in the above precondensed resin based on aromatic polyphenol, the repeating unit satisfies the characteristics of the above aromatic polyphenol, except that at least one of the carbon atoms of the aromatic ring that was not substituted is bonded to another unit.

[0070] As described above, the aromatic polyphenol can also include a mixture of the free molecular aromatic polyphenol and the precondensed resin based on the aromatic polyphenol. In particular, the aromatic polyphenol can also include a mixture of phloroglucinol and the precondensed resin based on phloroglucinol.

[0071] <<<Aromatic Monophenol>>> Next, the aromatic monophenols will be described. The aromatic monophenols include two embodiments. In one embodiment, the two ortho positions relative to the above hydroxy group are unsubstituted. In another embodiment, at least one ortho position and the para position relative to the above hydroxy group are unsubstituted. In the modification where at least one ortho position and the para position relative to the above hydroxy group are unsubstituted, it is preferable that a single ortho position is unsubstituted and the para position relative to the above hydroxy group is unsubstituted. Regardless of the above embodiment, it is preferable that the two ortho positions of the above hydroxy group are unsubstituted. This means that the two carbon atoms located on both sides (ortho positions) of the hydroxylated carbon atom (i.e., having the above hydroxy group) have simple hydrogen atoms. It is preferable that the remaining part of the above aromatic ring is unsubstituted. This means that the other carbon atoms of the remaining part of the above aromatic ring (other than the carbon atom having the above hydroxy group) have simple hydrogen atoms. The above aromatic monophenols contain a plurality of 6-membered aromatic rings, at least two of which each have a single hydroxy group, and for at least one of the above hydroxy groups, it is preferable that the two ortho positions relative to the above hydroxy group are unsubstituted, or at least one ortho position and the para position relative to the above hydroxy group are unsubstituted.

[0072] It is preferable that the two ortho positions relative to each hydroxy group of at least one 6-membered aromatic ring are unsubstituted. It is preferable that the two ortho positions relative to each hydroxy group of each 6-membered aromatic ring are unsubstituted. It is preferable that the remaining part of each aromatic ring is unsubstituted. This means that the other carbon atoms of the remaining part of each aromatic ring (other than the carbon atom having the above hydroxy group or the carbon atom having a group that binds the above aromatic rings together) have simple hydrogen atoms. It is preferable that one or each aromatic ring of the above aromatic monophenol is a benzene ring.

[0073] Examples of the aromatic monophenol include phenol, ortho-cresol, meta-cresol, para-cresol, ortho-chlorophenol, meta-chlorophenol, para-chlorophenol, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 4-vinylphenol, 4-ethylphenol, 4-isopropylphenol, 4-isobutylphenol, paracumaric acid, and the like.

[0074] The aromatic monophenol may be a precondensed resin based on the above aromatic monophenol. This precondensed resin preferably has the following components as a base: - at least one aromatic monophenol selected from the group consisting of phenol, ortho-cresol, meta-cresol, para-cresol, ortho-chlorophenol, meta-chlorophenol, para-chlorophenol, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 4-vinylphenol, 4-ethylphenol, 4-isopropylphenol, 4-isobutylphenol, paracumaric acid, and mixtures of these compounds; and - at least one compound capable of reacting with the monophenol containing at least one aldehyde group and / or at least one compound capable of reacting with the monophenol containing at least two hydroxymethyl groups having an aromatic ring.

[0075] A compound capable of reacting with a monophenol containing at least one aldehyde group and / or a compound capable of reacting with a monophenol containing at least two hydroxymethyl groups in an aromatic ring and capable of reacting with the above aromatic monophenol may be compound A or any other aldehyde. Preferably, the above compound capable of reacting with a monophenol containing at least one aldehyde group and / or the above compound capable of reacting with a monophenol containing at least two hydroxymethyl groups in an aromatic ring is an aromatic compound containing an aromatic ring having at least two functional groups, one of these functional groups is a hydroxymethyl group, and the other is an aldehyde group or a hydroxymethyl group, and is selected from the group consisting of formaldehyde, benzaldehyde, furfural, 2,5-furandicarboxaldehyde, 1,4-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,2-benzenedicarboxaldehyde and mixtures thereof. More preferably, when the above compound is an aromatic compound containing an aromatic ring having at least two functional groups, one of these functional groups is a hydroxymethyl group, and the other is an aldehyde group or a hydroxymethyl group, and this compound is selected from the group consisting of 5-(hydroxymethyl)furfural, 2,5-di(hydroxymethyl)furan and mixtures of these compounds.

[0076] Therefore, in the above precondensed resin based on an aromatic monophenol, the repeating unit satisfies the properties of the above aromatic monophenol, except that at least one of the carbon atoms of the above unsubstituted 6-membered aromatic ring is bonded to another unit.

[0077] As described above, the aromatic monophenol can also include a mixture of free molecules of the aromatic monophenol and a precondensed resin based on the aromatic monophenol. In particular, the aromatic monophenol can also include a mixture of phenol and a precondensed resin based on phenol.

[0078] In addition, in this specification, compound B is a compound having a structure in which an aromatic ring is modified with a hydroxy group. However, compounds having a structure in which an aromatic ring is modified with a hydroxy group include not only compounds having a structure in which an aromatic ring is modified with a hydroxy group, but also compounds derived from a structure in which an aromatic ring is modified with a hydroxy group.

[0079] Examples of the compound derived from a structure in which an aromatic ring is modified with a hydroxy group include, for example, a compound in which the hydroxy group possessed by the aromatic ring reacts with another compound. Examples of the compound derived from a structure in which an aromatic ring is modified with a hydroxy group include, for example, compounds having the following structures.

Chemical formula

[0080] As compound B, a phenol compound is preferable, an aromatic polyphenol or an aromatic monophenol is more preferable, and an aromatic polyphenol is even more preferable. The aromatic ring of the above aromatic polyphenol preferably has three hydroxy groups in the meta positions with respect to each other. Also, it is preferable that the two ortho positions with respect to each hydroxy group are unsubstituted. That is, it is more preferable to have three hydroxy groups in the meta positions with respect to each other and the two ortho positions with respect to each hydroxy group being unsubstituted. Here, the above aromatic polyphenol preferably has one aromatic ring, and it is more preferable that the aromatic ring is a benzene ring. In addition, the aromatic polyphenol is preferably a simple molecule having no repeating unit. That is, as compound B, the compound (phloroglucinol) represented by the above formula (B2) is most preferable.

[0081] A resin having compound A having a structure in which an aromatic ring is modified with a hydroxymethyl group and compound B having a structure in which an aromatic ring is modified with a hydroxy group as monomers may be any resin having compound A and compound B as monomers. Such a resin can be polymerized by reacting compound A and compound B according to a known method. And the above resin may be polymerized before being compounded into the rubber composition. That is, the above resin may first be synthesized according to a known method, and the synthesized resin may be compounded into the rubber composition. Also, the above resin may be polymerized after being compounded into the rubber composition. That is, the synthesis of the above resin may be carried out during the kneading and vulcanization of the rubber composition. Specifically, Compound A and Compound B may be added to the rubber composition, and when the rubber composition is kneaded and vulcanized, the resin may be produced, and a rubber composition containing the above resin may be prepared.

[0082] The content of the unit derived from Compound A in 100% by mass of the above resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, particularly preferably 60% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0083] The content of the unit derived from Compound B in 100% by mass of the above resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, particularly preferably 60% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0084] The total content of the unit derived from Compound A and the unit derived from Compound B in 100% by mass of the above resin is preferably 20% by mass or more, more preferably 40% by mass or more, still more preferably 60% by mass or more, particularly preferably 80% by mass or more, most preferably 90% by mass or more, even most preferably 95% by mass or more, still most preferably 98% by mass or more, and may be 100% by mass. When within the above range, the effect tends to be obtained more favorably. In this specification, the content of the unit derived from Compound A and the unit derived from Compound B is a value measured by NMR.

[0085] The content of the above resin (when compounded as compound A and compound B, it means the total compounding amount of compound A and compound B) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 8 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0086] It is preferable that the content of the above resin (parts by mass) / the content of the isoprene-based rubber (parts by mass) ≤ 0.5. The content of the above resin (parts by mass) / the content of the isoprene-based rubber (parts by mass) is preferably 0.4 or less, more preferably 0.3 or less, still more preferably 0.26 or less, and preferably 0.05 or more, more preferably 0.1 or more, still more preferably 0.15 or more. When within the above range, the effect tends to be obtained more favorably. This is presumably because when the amount of the above resin relative to the isoprene-based rubber is too large, the hardness difference between the sea-island tends to increase. In this relationship, the content of the above resin and the content of the isoprene-based rubber are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component. Also, the content of the above resin means the total compounding amount of compound A and compound B when compounded as compound A and compound B.

[0087] The above rubber composition may contain a resin other than the above resin. Examples of the resin include cyclopentadiene-based resins, terpene-based resins, rosin resins, coumarone-indene-based resins (including coumarone and indene monomer resins), olefin-based resins, polyurethane resins, acrylic resins, etc. These may be used alone or in combination of two or more. Also, they may be hydrogenated products (hydrogenated resins).

[0088] Examples of commercially available products of the above resin include products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Nippon Paint Co., Ltd., Nippon Catalyst Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc.

[0089] <Filler> The above rubber composition contains a filler (reinforcing filler). Examples of the filler include carbon black, silica, talc, clay, aluminum hydroxide, titanium oxide, etc. These may be used alone or in combination of two or more. Among them, carbon black and silica are preferred, and carbon black is more preferred.

[0090] The content of the filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 80 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 50 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0091] The carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nippon Carbon Co., Ltd., Columbia Carbon Co., etc. can be used. These may be used alone or in combination of two or more.

[0092] The nitrogen adsorption specific surface area (N 2 SA) of the carbon black is preferably 50 m 2 / g or more, more preferably 70 m 2 / g or more, still more preferably 90 m 2 / g or more. Also, the above N 2 SA is 200 m 2Preferably below / g, 150m 2 More preferably below / g, 130m 2 Even more preferably below / g. When within the above range, the effect tends to be better obtained. The nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

[0093] The content of carbon black is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, most preferably 35 parts by mass or more, and preferably 80 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be better obtained.

[0094] The content of carbon black in 100% by mass of the filler is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, most preferably 98% by mass or more, and may be 100% by mass. When within the above range, the effect tends to be better obtained. It is presumed that the higher the carbon ratio, the smaller the hardness difference between the sea-island phases and the less likely stress concentration is.

[0095] Examples of silica include dry-process silica (anhydrous silica), wet-process silica (hydrous silica), etc. Among them, wet-process silica is preferred because of its many silanol groups. As commercial products, products of Degussa, Rhodia, Tosoh Silica Corporation, Solvay Japan, Tokuyama Corporation, etc. can be used. These may be used alone or in combination of two or more.

[0096] As for silica, the nitrogen adsorption specific surface area (N 2 SA) is preferably 50m 2 / g or more, more preferably 100m 2 / g or more, even more preferably 150m 2 / g or more. Also, the N of silica 2The upper limit of SA is not particularly limited, but is preferably 350 m 2 / g or less, more preferably 250 m 2 / g or less, still more preferably 200 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. In addition, the N of silica 2 SA is a value measured by the BET method in accordance with ASTM D3037-93.

[0097] The content of silica is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less, and most preferably 15 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0098] <Compounding agents other than rubber component, resin, and filler> When containing silica, it is preferable to use silica in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide and other sulfide-based ones, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and other mercapto-based ones, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl-based ones, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and other amino-based ones, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and other glycidoxy-based ones, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane and other nitro-based ones, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and other chloro-based ones can be mentioned. As commercially available products, for example, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., Toray Dow Corning Co., Ltd. etc. can be used. These may be used alone or in combination of two or more kinds.

[0099] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of silica. When it is within the above range, the effect tends to be obtained more favorably.

[0100] The above rubber composition preferably contains a liquid plasticizer (a plasticizer in a liquid state at normal temperature (25 °C)). The liquid plasticizer (a plasticizer in a liquid state at normal temperature (25 °C)) is not particularly limited, and examples thereof include oils and liquid polymers (such as liquid diene-based polymers). These may be used alone or in combination of two or more. Among them, oil is preferable.

[0101] The content of the liquid plasticizer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and particularly preferably 25 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0102] Examples of the oil include process oil, vegetable oil, or a mixture thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Examples of the vegetable oil include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, etc. As commercial products, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Corporation, Oleo GmbH, H&R AG, Toyokuni Oil Co., Ltd., Showa Shell Sekiyu KK, Fuji Kogyo Co., Ltd., Nisshin Oillio Group Ltd., etc. can be used. These can be used alone or in combination of two or more. Among them, process oil (such as paraffinic process oil, aromatic process oil, naphthenic process oil, etc.) and vegetable oil are preferred, and aromatic process oil is more preferred.

[0103] The content of the oil is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and particularly preferably 25 parts by mass or less. When within the above range, the effect tends to be obtained more favorably. Note that the content of the oil also includes the oil contained in the extender oil.

[0104] Examples of the liquid diene polymers include liquid styrene-butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene-isoprene copolymers (liquid SIR), liquid styrene-butadiene-styrene block copolymers (liquid SBS block polymers), liquid styrene-isoprene-styrene block copolymers (liquid SIS block polymers), liquid farnesene polymers, liquid farnesene-butadiene copolymers, etc., which are in a liquid state at 25°C. These may have polar groups modifying the terminals or the main chain. Also, hydrogenated products thereof can be used. These may be used alone or in combination of two or more.

[0105] The content of the liquid diene polymer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and particularly preferably 25 parts by mass or less. When within the above range, the effects tend to be obtained more favorably.

[0106] The above rubber composition may contain an antioxidant. Examples of the anti-aging agent include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, etc. As commercially available products, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. These may be used alone or in combination of two or more. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and p-phenylenediamine-based anti-aging agents are more preferred.

[0107] The content of the anti-aging agent is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, and preferably 12 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0108] The above rubber composition may contain wax. The wax is not particularly limited, and examples include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers of ethylene, propylene, etc. As commercially available products, products of Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0109] The wax content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0110] The above rubber composition may contain zinc oxide. As the zinc oxide, conventionally known ones can be used. As commercially available products, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Sho-Doh Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0111] The content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0112] The above rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used. As commercially available products, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0113] The content of stearic acid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0114] The above rubber composition contains sulfur. In the rubber composition after vulcanization, most of the sulfur is bonded to the rubber component. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are commonly used as crosslinking agents in the rubber industry. As commercially available products, products of companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys, Nippon Retorting Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0115] The sulfur content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 1 part by mass or more, and preferably 3.5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 2.5 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0116] The above rubber composition may contain a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyldisulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazole sulfenamide, and N,N′-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolylbiguanidine. As commercially available products, products of companies such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Industry Co., Ltd. can be used. These may be used alone or in combination of two or more. Among them, sulfenamide-based vulcanization accelerators are preferred.

[0117] The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 3 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0118] In addition to the above components, the rubber composition may further contain additives generally used in the tire industry, such as organic peroxides. The content of these additives is preferably 0.1 to 200 parts by mass based on 100 parts by mass of the rubber component.

[0119] The rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

[0120] As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120°C or lower, preferably 80 to 110°C. Further, the composition kneaded with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0121] The rubber composition can be used, for example, for tire members such as tread (cap tread), sidewall, base tread, undertread, shoulder, clinch, bead apex, breaker cushion rubber, carcass cord coating rubber, insulation, chafing, inner liner, etc., and side reinforcement rubber and bead reinforcement rubber of a run-flat tire (as a rubber composition for tires). Among them, it is preferably used for sidewalls, clinches, side reinforcement rubber, and bead reinforcement rubber, and more preferably used for sidewalls.

[0122] The tire (pneumatic tire, etc.) of the present invention is manufactured by a normal method using the above rubber composition. That is, a rubber composition blended with various additives as required is extruded in an unvulcanized state according to the shape of each member of the tire (especially the sidewall), molded by a normal method on a tire molding machine, bonded together with other tire members to form an unvulcanized tire, and then heated and pressurized in a vulcanizer to manufacture the tire.

[0123] Note that at least a part of the tire member of the above tire may be composed of the above rubber composition, or all of it may be composed of the above rubber composition.

[0124] The above tire is preferably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a motorcycle tire, a racing tire, a winter tire (studless tire, snow tire, stud tire), an all-season tire, a run-flat tire, an aircraft tire, a mine tire, etc.

Examples

[0125] Based on the examples, the present invention will be specifically described, but the present invention is not limited to these only.

[0126] The various chemicals used in the examples and comparative examples will be described below. NR: TSR20 (NR) BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass) SBR: Nipol 1502 manufactured by Nippon Zeon Co., Ltd. (E-SBR, styrene content: 23.5% by mass) Carbon black: Diablack N220 (N manufactured by Mitsubishi Chemical Corporation) 2 SA: 111m 2 / g) Silica: Ultrasil VN3 (N manufactured by Evonik Degussa GmbH) 2 SA: 175m 2 / g) Wax: Oz Ace 0355 manufactured by Nippon Seiro Co., Ltd. Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Oil: Diana Process AH-24 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Resin: 5-(hydroxymethyl)furfural (manufactured by Aldrich, corresponding to Compound A) and phloroglucinol (manufactured by Alfa Aesar, corresponding to Compound B) were blended at a mass ratio of 1:1. Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powder sulfur containing 5% by mass of oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0127] (Examples and Comparative Examples) According to the formulation contents shown in Tables 1 and 2, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur, vulcanization accelerator, and resin (Compound A and Compound B) were kneaded at 150 °C for 5 minutes to obtain a kneaded product. Next, sulfur, vulcanization accelerator, and resin (Compound A and Compound B) were added to the obtained kneaded product, and it was kneaded at 80 °C for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-vulcanized at 150 °C for 12 minutes to obtain a vulcanized rubber composition. The following evaluations were performed using the obtained vulcanized rubber composition, and the results are shown in Tables 1 and 2. The reference comparative example in Table 1 was designated as Comparative Example 1-1, and the reference comparative example in Table 2 was designated as Comparative Example 2-1.

[0128] (Fracture properties) In accordance with "Vulcanized Rubber and Thermoplastic Rubber - Method for Determining Tensile Properties" of JIS K 6251, the tensile strength and elongation at break of a rubber slab sheet (2 mm × 130 mm × 130 mm) made of the above vulcanized rubber composition were measured. Then, using the obtained measurement results, the fracture energy was calculated by tensile strength × elongation at break / 2, and taking the fracture energy index (fracture property index) of the reference comparative example as 100, the measurement results of each formulation were expressed as an index according to the following calculation formula. The larger the index, the better the fracture property. (Fracture energy index) = (Fracture energy of each formulation) / (Fracture energy of the reference comparative example) × 100

[0129] (Crack resistance flexure property) Using the vulcanized rubber composition, samples were prepared based on JIS-K-6260 "Vulcanized Rubber and Thermoplastic Rubber - Demattia Flexure Crack Test Method", and a flexure crack growth test was conducted. After repeating the 70% elongation 1,000,000 times to bend the rubber sheet, the length of the generated cracks was measured. Taking the reciprocal of the measured value (length) of the reference comparative example as 100, it was expressed as an index. The larger the index, the more the crack growth is suppressed, indicating excellent crack resistance flexure property.

[0130] (Fracture properties after heat deterioration) The vulcanized rubber composition (new sample) was heat-deteriorated in an oven at 100 °C for 7 days to obtain a vulcanized rubber composition after heat deterioration (deteriorated sample). Using the obtained vulcanized rubber composition after heat deterioration, the fracture energy was calculated according to the above method, and taking the fracture energy index (fracture property index) of the reference comparative example as 100, it was expressed as an index. The larger the index, the better the fracture properties after heat deterioration.

[0131] [Table 1]

[0132] [Table 2]

[0133] From Tables 1 and 2, it was found that an example containing a rubber component comprising at least an isoprene-based rubber and a styrene-butadiene rubber and / or a butadiene rubber and a filler, and a resin having as monomers Compound A with a structure in which an aromatic ring is modified with a hydroxymethyl group and Compound B with a structure in which an aromatic ring is modified with a hydroxy group, and having a content of the isoprene-based rubber of 35% by mass or more in 100% by mass of the rubber component can improve the comprehensive performance of fracture properties, crack resistance to flexure, and fracture properties after heat deterioration (represented by the sum of three indices of fracture properties, crack resistance to flexure, and fracture properties after heat deterioration).

[0134] From the comparison between Example 1-1 and Comparative Examples 1-1 to 1-3, and the comparison between Example 2-1 and Comparative Examples 2-1 to 2-3, it was found that by using in combination a specific rubber component and the above resin, the comprehensive performance of fracture properties, crack resistance to flexure, and fracture properties after heat deterioration can be synergistically improved.

Claims

1. A rubber composition for tires comprising a rubber component containing at least an isoprene rubber and a styrene-butadiene rubber and / or a butadiene rubber, and a filler, comprising a resin having as monomers a compound A having a structure in which an aromatic ring is modified with a hydroxymethyl group and a compound B having a structure in which an aromatic ring is modified with a hydroxy group, wherein the compound A is an aromatic compound containing at least one aromatic ring having at least two functional groups, one of these functional groups being a hydroxymethyl group and the other being an aldehyde group or a hydroxymethyl group, the compound B is a phenol compound, the content of the isoprene rubber in 100% by mass of the rubber component is 35% by mass or more and 80% by mass or less, the content (parts by mass) of the butadiene rubber or styrene-butadiene rubber / the content (parts by mass) of the isoprene rubber is 1.10 or more and 2.50 or less, A rubber composition for tires used for sidewalls.

2. The rubber composition for tires according to claim 1, wherein the content of carbon black in 100% by mass of the filler is 80% by mass or more.

3. The rubber composition for tires according to claim 1 or 2, wherein the content (parts by mass) of the resin / the content (parts by mass) of the isoprene rubber ≦ 0.

5.

4. A tire having a sidewall using the rubber composition according to any one of claims 1 to 3.

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