tire

Abstract

To provide a tire excellent in overall performance of crack growth resistance and pinch cut resistance.SOLUTION: A tire comprising a support member comprising a polyamide polyether elastomer, where polyamide polyether elastomer content (PA (mass%)) in the support member and sulfur content (TSp (mass%)) of ply topping rubber satisfy the following formula (1): PA-TSp<15.0.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a tire. [Background technology]

[0002] A tire is composed of various components each having various performance characteristics, and components that support the tire, such as sidewalls, are required to have physical properties such as crack growth resistance, external damage resistance, etc. For example, Patent Document 1 discloses a tire that contains a polyamide polyether elastomer or the like and has excellent external damage resistance and flex fatigue resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-77809 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a great demand for improvements in tire performance, and further improvements in performance such as crack growth resistance and pinch cut resistance are desired.

[0005] An object of the present invention is to solve the above problems and to provide a tire that is excellent in overall performance such as crack growth resistance and pinch cut resistance. [Means for solving the problem]

[0006] The present invention provides a tire having a support member comprising a polyamide polyether elastomer, The tire relates to a polyamide polyether elastomer content (PA (mass %)) in the support member and a sulfur content (TSp (mass %)) in the bright topping rubber that satisfy the following (Equation 1). (Formula 1) PA-TSp<15.0

[0007] It is preferable that the PA (mass %) and the TSp (mass %) satisfy the following formula. PA-TSp≦12.0

[0008] The PA (mass %) preferably satisfies the following formula: 6.0≦PA≦11.0

[0009] It is preferable that the TSp (mass %) satisfies the following formula: 1.7≦TSp≦2.6

[0010] The support member preferably contains 5 to 30 parts by mass of the polyamide polyether elastomer per 100 parts by mass of the rubber component.

[0011] The support member preferably contains 3 to 20 parts by mass of acid-modified polyolefin per 100 parts by mass of the rubber component.

[0012] It is preferable that the support member contains 20 to 60% by mass of isoprene-based rubber and 40 to 80% by mass of butadiene rubber in 100% by mass of the rubber component, and that the bright topping rubber contains 50 to 85% by mass of isoprene-based rubber and 15 to 50% by mass of styrene-butadiene rubber in 100% by mass of the rubber component.

[0013] The support member has a nitrogen adsorption specific surface area of ​​55 m per 100 parts by mass of the rubber component. 2 The carbon black content of 10 to 60 parts by mass / g or less is preferably 10 to 60 parts by mass.

[0014] The bright topping rubber preferably contains 0.5 to 5.0 parts by mass of hardened resin per 100 parts by mass of the rubber component.

[0015] It is preferable that the sulfur content (TSs (mass %)) of the support member and the sulfur content (TSp (mass %)) of the bright topping rubber satisfy the following (Equation 2). (Equation 2) TSp-TSs<2.0 [Effects of the Invention]

[0016] The present invention provides a tire having a support member containing a polyamide polyether elastomer, in which the polyamide polyether elastomer content (PA (mass%)) in the support member and the sulfur content (TSp (mass%)) of the bright topping rubber satisfy the following (Equation 1), thereby providing a tire with excellent overall performance in terms of crack growth resistance and pinch cut resistance. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a partial cross-sectional view of a tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention relates to a tire having a support member containing a polyamide polyether elastomer, in which the polyamide polyether elastomer content (PA (% by mass)) in the support member and the sulfur content (TSp (% by mass)) of the bright topping rubber satisfy the above-mentioned (Equation 1). Such a tire has excellent overall performance in terms of crack growth resistance and pinch cut resistance.

[0019] When a tire passes over a bump such as a pothole in the road surface, a large impact force is applied to the tire, and the tire is pinched between the road surface and the rim flange, causing significant deformation in the portion from the sidewall to the clinch, and large tension is applied to the cords contained in the carcass. Depending on the level of tension, the cords may break; this damage accompanied by cord breakage is called pinch cut. The tire of the present invention has excellent overall performance in terms of pinch cut resistance, which suppresses such pinch cuts, and crack growth resistance. By configuring at least one of the sidewall, side reinforcing layer (side reinforcing layer in a run-flat tire), clinch, base tread, and support members other than the ply, such as cord topping rubber, to contain a polyamide polyether elastomer and satisfy the above (Equation 1), deformation of the portion from the sidewall to the clinch is prevented, cord breakage is suppressed, and pinch cuts can be suppressed.

[0020] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is responsible. While incorporating polyamide polyether elastomer into tire support components such as sidewalls can achieve both high hardness and crack growth resistance, there is a concern that the amount of double bonds at the interface between the support component and the bright topping rubber of the ply may be reduced, resulting in potential delamination at the interface. In response to this issue, adjusting the polyamide polyether elastomer content (PA) in the support component and the sulfur content (TSp) of the bright topping rubber to satisfy the formula (1) "PA-TSp<15.0" facilitates bonding of the sulfur in the bright topping rubber to the double bonds at the interface reduced by the polyamide polyether elastomer, thereby improving the reinforcement at the interface between the support component and the ply. This improves the reinforcement at the interface while suppressing deformation of the support component, thereby improving pinch cut resistance against large deformations such as when driving over a curb or hitting a pothole. This is expected to significantly improve the overall crack growth resistance and pinch cut resistance of the tire.

[0021] In this way, the problem (objective) of improving the overall performance of crack growth resistance and pinch cut resistance is solved by configuring a tire that has a support member containing a polyamide polyether elastomer and in which the polyamide polyether elastomer content (PA (% by mass)) in the support member and the sulfur content (TSp (% by mass)) of the bright topping rubber satisfy (Equation 1) "PA-TSp<15.0." In other words, the configuration of "PA-TSp<15.0" does not define the problem (objective); the object of the present application is to improve the overall performance of crack growth resistance and pinch cut resistance, and a configuration that satisfies the parameter is used as a means to achieve this.

[0022] The support member is a member that supports a tire, and examples thereof include a sidewall, a side reinforcing layer (a side reinforcing layer in a run-flat tire), a clinch, a base tread, a cord topping rubber other than a ply, etc. Among these, the support member is preferably applied to a sidewall, a side reinforcing layer, and a clinch from the viewpoint of excellent overall performance in terms of crack growth resistance and pinch cut resistance.

[0023] The tire component covered with the ply topping rubber (carcass topping rubber) is the ply (carcass).

[0024] In the tire, the content of polyamide polyether elastomer (PA (mass %)) in the support member and the amount of sulfur (TSp (mass %)) in the bright topping rubber satisfy the following (Equation 1). (Formula 1) PA-TSp<15.0

[0025] From the viewpoint of overall performance of crack growth resistance and pinch cut resistance, PA-TSp is preferably 12.0 or less, more preferably 9.0 or less, even more preferably 7.0 or less, and particularly preferably 6.0 or less. There is no particular restriction on the lower limit, but it is preferably 0.5 or more, more preferably 2.5 or more, even more preferably 3.0 or more, and particularly preferably 3.5 or more.

[0026] The PA content is preferably 4.5% by mass or more, more preferably 6.0% by mass or more, even more preferably 6.5% by mass or more, and particularly preferably 7.0% by mass or more. The upper limit is preferably 16.0% by mass or less, more preferably 13.0% by mass or less, even more preferably 11.0% by mass or less, particularly preferably 9.0% by mass or less, and most preferably 8.5% by mass or less. By keeping the PA content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0027] TSp is preferably 1.5% by mass or more, more preferably 1.7% by mass or more, even more preferably 1.8% by mass or more, and particularly preferably 1.9% by mass or more. The upper limit is preferably 3.0% by mass or less, more preferably 2.6% by mass or less, even more preferably 2.4% by mass or less, and particularly preferably 2.3% by mass or less. By keeping it within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0028] PA (polyamide polyether elastomer content in the support member) is the amount (% by mass) of polyamide polyether elastomer in the total amount (100% by mass) of all components blended into the rubber composition (unvulcanized rubber composition) constituting the support member. TSp (sulfur content in the ply topping rubber) is the sulfur content in the rubber composition for ply topping (rubber composition after vulcanization) constituting the ply. TSs (sulfur content in the support member) described below is the sulfur content in the rubber composition for support member (rubber composition after vulcanization) constituting the support member, and can be measured by the method described in the Examples below.

[0029] The method for adjusting TSp and TSs (described later) is not particularly limited, but the values ​​tend to increase, for example, by increasing the blending ratio of chemicals containing sulfur atoms, such as sulfur, vulcanization accelerators, and silane coupling agents.

[0030] <Supporting member> The tire includes a support member including a polyamide polyether elastomer. The support member is made of, for example, a rubber composition containing a polyamide polyether elastomer (rubber composition for support member).

[0031] (Polyamide polyether elastomer) In the rubber composition for a support member, the content of the polyamide polyether elastomer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 12 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of overall performance such as crack growth resistance and pinch cut resistance. The upper limit of the content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 22 parts by mass or less. By keeping the content within the above range, it tends to be possible to achieve both high hardness and crack growth resistance. Although the reason for such an effect is not entirely clear, it is presumed that by blending a predetermined amount of polyamide polyether elastomer, high hardness can be achieved, thereby improving pinch cut resistance during large deformation, without impairing adhesion performance with adjacent members.

[0032] The melting point of the polyamide polyether elastomer is preferably 70 to 160° C. The lower limit is more preferably 90° C. or higher, and the upper limit is more preferably 150° C. or lower. The melting point can be measured under a nitrogen atmosphere using, for example, a differential scanning calorimeter "DSC-50" manufactured by Shimadzu Corporation. Specifically, the temperature was raised from room temperature to 230°C at a rate of 10°C / min (first temperature rise run), held at 230°C for 10 minutes, then lowered to -100°C at a rate of 10°C / min (first temperature fall run), and then raised to 230°C at a rate of 10°C / min (second temperature rise run). From the obtained DSC chart, the exothermic peak temperature in the first temperature fall run can be measured as the crystallization temperature (Tc), and the endothermic peak temperature in the second temperature rise run can be measured as the melting point (Tm).

[0033] Examples of the polyamide polyether elastomer used in the rubber composition for a support member include copolymers having a hard segment containing polyamide and a soft segment containing polyether. Among them, from the viewpoint of overall performance such as crack growth resistance and pinch cut resistance, a block copolymer having a polyamide block (hard segment) and a polyether block (soft segment) is preferred, and a block copolymer having an aliphatic polyamide block (hard segment) and an aliphatic polyether block (soft segment) is more preferred.

[0034] Specific examples of polyamide polyether elastomers include compounds having a structure represented by the following formula (I). -[A k -XB m ] n - (I) (In the formula, A k represents a polyamide block, and B m represents a polyether block, X represents a linking group that links the polyamide block and the polyether block, and n represents an integer of 1 or more.

[0035] In the above formula, the repeating unit [A k -XB m ] between the polyamide blocks (A k ), polyether block (B m ) may be the same or different. Each bonding group X may be the same or different and is preferably —CO—NH— or —CO—O—.

[0036] The weight average molecular weight (Mw) of polyamide polyether elastomer is 1.0 x 10 4 ~2.0×10 5 In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​calculated in terms of standard polystyrene based on values ​​measured by gel permeation chromatography (GPC).

[0037] Polyamide block (Ak ) may be, for example, those derived from the polymerization of one or more polyamide-forming monomers such as lactams, aminocarboxylic acids, and salts of diamines and dicarboxylic acids.

[0038] Examples of lactams include aliphatic lactams having 5 to 20 carbon atoms, such as ε-caprolactam, ω-heptalactam, ω-capryllactam, ω-undecalactam, and ω-dodecalactam, and among these, aliphatic lactams having 5 to 12 carbon atoms are preferred. Examples of aminocarboxylic acids include ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminocaprylic acid, ω-aminoperconic acid, ω-aminocapric acid, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid, and among these, aminocarboxylic acids having 5 to 11 carbon atoms are preferred. Examples of diamines in the salts of diamines and dicarboxylic acids include diamines having 2 to 20 carbon atoms, such as ethylenediamine, triethylenediamine, tetraethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, phenylenediamine, and meta-xylylenediamine. Examples of dicarboxylic acids in the salts of diamines and dicarboxylic acids include dicarboxylic acids having 2 to 36 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, terephthalic acid, isophthalic acid, suberic acid, azelaic acid, nonanedicarboxylic acid, decanedicarboxylic acid, tetradecanedicarboxylic acid, octadecanedicarboxylic acid, fumaric acid, phthalic acid, xylylenedicarboxylic acid, and dimer acid (an unsaturated dicarboxylic acid having 36 carbon atoms synthesized from unsaturated fatty acids mainly composed of linoleic acid or oleic acid). Among the salts of diamines and dicarboxylic acids, the salts of diamines and dicarboxylic acids exemplified above are preferred, and a salt of one selected from the group consisting of ethylenediamine, triethylenediamine, tetraethylenediamine, and hexamethylenediamine with one selected from the group consisting of oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, terephthalic acid, and isophthalic acid is more preferred.

[0039] Examples of polyamide units constituting polyamide blocks include ring-opening polymers of lactams such as polycaprolactam (nylon 6), polyheptolactam (nylon 7), polycapryllactam (nylon 8), polynonanolactam (nylon 9), polyundecanolactam (nylon 11), and polylauryllactam (nylon 12); ring-opening copolymers of lactams such as caprolactam / lauryllactam copolymer (nylon 6 / 12) and caprolactam / nonanolactam copolymer (nylon 6 / 9); polyethylenediamineadipamide (nylon 26), polytetramethyleneadipamide (nylon 46), polyhexamethyleneadipamide (nylon 66), polyhexamethylenesebacamide (nylon 610), polyhexamethylenedodecamide (nylon 612), and polyoctamethicone. Polycondensates of diamines and dicarboxylic acids such as ethylenediamine adipamide (nylon 86), polydecamethylene adipamide (nylon 106), polydecamethylene sebacamide (nylon 108), and ethylenediamine adipamide / hexamethylene adipamide copolymer (nylon 26 / 66); copolymers of lactams / diamines / dicarboxylic acids such as caprolactam / hexamethylene adipamide copolymer (nylon 6 / 66), lauryllactam / hexamethylene adipamide copolymer (nylon 12 / 66), caprolactam / hexamethylene adipamide / hexamethylene diammonium sebacate copolymer (nylon 66 / 610), and ethyleneammonium adipate / hexamethylene adipamide / hexamethylene diammonium sebacate copolymer (nylon 6 / 66 / 610). Among these, ring-opening polymers and copolymers of lactams are preferred, and polylauryllactam (nylon 12) is more preferred.

[0040] Polyether block (B mExamples of the polyoxyalkylene polyol include polyoxyalkylene polyols (polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, polyoxytetramethylene diol, polyoxypropylene diol, polyoxytetramethylene oxypropylene diol, etc.), ABA triblock polyethers represented by the following formula (II), and polyether diamines, which are derived by polymerizing one or more polyethers. The polyethers may be those whose terminals are modified with amines.

[0041] [ka] (In the formula, x is an integer of 1 to 20, y is an integer of 4 to 50, and z is an integer of 1 to 20.)

[0042] x is preferably an integer of 2 to 6. y is preferably an integer of 6 to 12. z is preferably an integer of 1 to 5.

[0043] The number average molecular weight (Mn) of the hard segment is preferably 300 or more, with the upper limit being preferably 15,000 or less, more preferably 600 or less. The number average molecular weight (Mn) of the soft segment is preferably 200 or more, more preferably 650 or more, with the upper limit being preferably 6,000 or less, more preferably 2,000 or less. The mass ratio of the hard segment to the soft segment (hard segment:soft segment) is preferably 20:80 to 95:5, more preferably 30:70 to 80:20.

[0044] The combination of the hard segment and the soft segment may be any of the combinations of the hard segment and the soft segment mentioned above, but among them, the combination of the ring-opening polycondensation product of lauryllactam and polyethylene glycol, the combination of the ring-opening polycondensation product of lauryllactam and polypropylene glycol, the combination of the ring-opening polycondensation product of lauryllactam and polytetramethylene ether glycol, the combination of the ring-opening polycondensation product of lauryllactam and the ABA triblock polyether of the above formula (II) is preferred, and the combination of the ring-opening polycondensation product of lauryllactam and the ABA triblock polyether of the above formula (II) is more preferred. An example of a commercially available polyamide polyether elastomer having a combination of the ring-opening polycondensation product of lauryllactam and the ABA triblock polyether of the above formula (II) is UBESTA XPA 9040X1.

[0045] Commercially available polyamide polyether elastomers include the UBESTA XPA series manufactured by Ube Industries, Ltd. (UBESTA XPA 9040X1, 9040F1, 9048X1, 9048F1, 9055X1, 9055F1, 9063X1, 9063F1, 9068X1, 9068F1, 9040X2, 9048X2, 9040F2, 9048F2, 9035X, etc.). The polyamide polyether elastomers may be used alone or in combination of two or more.

[0046] (acid-modified polyolefin) From the viewpoint of overall performance such as crack growth resistance and pinch cut resistance, the rubber composition for a support member preferably contains an acid-modified polyolefin.

[0047] In the rubber composition for a support member, the content of the acid-modified polyolefin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of overall performance such as crack growth resistance and pinch cut resistance. The upper limit of the content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. By keeping the content within the above range, it tends to be possible to achieve both high hardness and crack growth resistance. Although the reason for such effects is not necessarily clear, it is presumed that the incorporation of a predetermined amount of acid-modified polyolefin improves the dispersion of the polyamide polyether elastomer in the system, effectively forms a network, and improves crack growth resistance and pinch cut resistance.

[0048] The acid-modified polyolefin is preferably solid at 23° C. The melting point of the acid-modified polyolefin is preferably 105 to 146° C., more preferably 110 to 145° C. The melting point of the acid-modified polyolefin can be measured in accordance with ASTM D2117.

[0049] Examples of acid-modified polyolefins include polyolefins modified with carboxylic acid. The skeleton of the acid-modified polyolefin may be either a homopolymer or a copolymer. The main chain of the acid-modified polyolefin is preferably, for example, a polyolefin having a repeating unit formed from an olefin. Examples of olefins include ethylene; α-olefins such as propylene, 1-butene, and 1-octene; and the like.

[0050] Examples of polyolefins constituting the skeleton (main chain) of the acid-modified polyolefin include homopolymers such as polyethylene, polypropylene, polybutene, and polyoctene; copolymers formed from at least two types of olefins; etc. Among these, homopolymers are preferred, and polypropylene and polyethylene are more preferred.

[0051] Examples of polyethylene include low-density to high-density polyethylene. Among them, high-density polyethylene is preferred. When the main chain of the acid-modified polyolefin is high-density polyethylene, the density of such acid-modified polyolefin is 940 to 980 kg / m 3 The density of the acid-modified polyolefin can be measured in accordance with ASTM D1505.

[0052] Examples of carboxylic acids that modify polyolefins include unsaturated carboxylic acids. Specific examples include monocarboxylic acids such as acrylic acid and methacrylic acid; dicarboxylic acids such as maleic acid, fumaric acid, crotonic acid, and itaconic acid; and acid anhydrides. Examples of acid anhydrides include anhydrides of dicarboxylic acids. Of these, maleic anhydride, maleic acid, and acrylic acid are preferred.

[0053] Among the above-mentioned acid-modified polyolefins, polyolefins modified with acid anhydrides are preferred, and polyolefins modified with maleic anhydride are more preferred.

[0054] In the acid-modified polyolefin, the position of the carboxylic acid bonded to the main chain is not particularly limited, and examples thereof include the terminal and the side chain. In particular, it is preferable that the carboxylic acid be bonded to the main chain as a side chain. The carboxylic acid and the main chain can be bonded directly or via an organic group. The organic group is not particularly limited.

[0055] The method for producing the acid-modified polyolefin is not particularly limited, and includes conventionally known methods, such as a production method by graft polymerization.

[0056] Commercially available acid-modified polyolefins include maleic anhydride-modified polypropylenes such as Admer QE060 (manufactured by Mitsui Chemicals, Inc.) and maleic anhydride-modified high-density polyethylenes such as Admer HE810 (manufactured by Mitsui Chemicals, Inc.) The acid-modified polyolefins can be used alone or in combination of two or more.

[0057] (rubber component) Examples of rubber components that can be used in the rubber composition for a support member include diene rubbers. Examples of diene rubbers include isoprene rubbers, butadiene rubbers (BR), styrene butadiene rubbers (SBR), styrene isoprene butadiene rubbers (SIBR), ethylene propylene diene rubbers (EPDM), chloroprene rubbers (CR), and acrylonitrile butadiene rubbers (NBR). Other examples include butyl rubbers and fluororubbers. These may be used alone or in combination of two or more. Among these, from the viewpoint of overall performance such as crack growth resistance and pinch cut resistance, isoprene rubbers, BR, and SBR are preferred, and isoprene rubbers and BR are more preferred.

[0058] The diene rubber may be an unmodified diene rubber or a modified diene rubber. The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. Examples include terminal-modified diene rubbers (terminal-modified diene rubbers having the functional group at the terminal) in which at least one terminal of the diene rubber has been modified with a compound (modifier) ​​having the functional group, main-chain-modified diene rubbers having the functional group at the main chain, main-chain-terminal-modified diene rubbers having the functional group at the main chain and at the terminals (for example, main-chain-terminal-modified diene rubbers having the functional group at the main chain and at least one terminal modified with the modifier), and terminal-modified diene rubbers modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0059] 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 imido 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, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0060] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, and TSR20, which are commonly used in the rubber industry. Examples of IR include IR2200 and other commonly used rubber products. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0061] In the rubber composition for a support member, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The upper limit is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0062] The BR is not particularly limited, and examples thereof include high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). These may be used alone or in combination of two or more. Of these, the BR preferably contains high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0063] The BR may be unmodified or modified. The modified BR may be a modified BR into which the same functional group as that of the modified diene rubber has been introduced.

[0064] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0065] In the rubber composition for a support member, the BR content in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. By keeping the BR content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0066] In the rubber composition for a support member, the total content of the isoprene-based rubber and BR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. There is no particular upper limit and it may be 100% by mass. By keeping it within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0067] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. These may be used alone or in combination of two or more.

[0068] The SBR may be unmodified or modified, and the modified SBR may be modified SBR into which the same functional groups as those in modified diene rubbers have been introduced.

[0069] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0070] In the rubber composition for a support member, the content of SBR in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, and may be 0% by mass. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0071] (filling material) The rubber composition for a support member preferably contains a filler from the viewpoint of overall performance such as crack growth resistance and pinch cut resistance.

[0072] The filler is not particularly limited, and materials known in the rubber field can be used, including, for example, inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. Of these, carbon black and silica are preferred, and carbon black is more preferred.

[0073] In the rubber composition for a support member, the content of the filler (total content of the fillers) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0074] Carbon black that can be used in the rubber composition for a support member is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products that can be used include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone, or two or more types may be used in combination.

[0075] The nitrogen adsorption specific surface area (N2SA) of carbon black is 200m 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 / g or less is more preferable. 2 / g or more is preferable, and 10m 2 By setting the value within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0076] In the rubber composition for a support member, the carbon black content (total amount of carbon black) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 45 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 55 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0077] In the rubber composition for the support member, from the viewpoint of the overall performance of crack growth resistance and pinch cut resistance, it is particularly preferable that the nitrogen adsorption specific surface area (N2SA) is 55m 2 It is preferable that the carbon black content is 50 m / g or less. 2 / g or less, more preferably 45m 2 / g or less. The lower limit is not particularly limited, but is 5m 2 / g or more is preferable, and 10m 2 / g or more is more preferable.

[0078] In the rubber composition for the support member, N2SA55m 2 From the viewpoint of overall performance such as crack growth resistance and pinch cut resistance, the carbon black content of 0.1 to 1.0 g / g or less is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less. By keeping the content within the above range, it tends to be possible to achieve both low heat buildup and crack growth resistance. The reason why such an effect is obtained is not necessarily clear, but N2SA55m 2 It is presumed that compounding carbon black at a concentration of 0.15 or less per 1000g improves the balance between reinforcement and flexibility within the rubber system, and also improves crack growth resistance.

[0079] (silica) Examples of silica that can be used in the rubber composition for a support member include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred because it contains a large number of silanol groups. Commercially available products include those from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation. These may be used alone or in combination of two or more.

[0080] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 300 m 2 / g or less, more preferably 250m 2 / g or less, more preferably 200m 2By setting the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0081] When the rubber composition for a support member contains silica, the content thereof is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0082] (Silane coupling agent) When the rubber composition for a support member contains silica, it preferably contains a silane coupling agent. The silane coupling agents may be used alone or in combination of two or more.

[0083] The silane coupling agent is not particularly limited, and examples thereof include 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-dimethylthiocalcium nitrate, Examples include sulfide-based compounds such as bamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those from Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0084] In the rubber composition for a support member, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, relative to 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0085] (plasticizer) A plasticizer may be blended into the rubber composition for a support member. A plasticizer is a material that imparts plasticity to a rubber component, and examples thereof include liquid plasticizers (plasticizers that are liquid at room temperature (25°C)) and resins (resins that are solid at room temperature (25°C)). These may be used alone or in combination of two or more.

[0086] In the rubber composition for a support member, the content of the plasticizer (total amount of plasticizer) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0087] Liquid plasticizers (plasticizers that are liquid at room temperature (25°C)) that can be used in the rubber composition for a support member are not particularly limited, and examples include oils, liquid polymers (liquid resins, liquid diene-based polymers, etc.), etc. These may be used alone or in combination of two or more.

[0088] In the rubber composition for a support member, the content of the liquid plasticizer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved. The oil content is also preferably in a similar range.

[0089] Examples of oils include process oils, vegetable oils, and mixtures thereof. Examples of process oils that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils that can be used 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, and tung oil. Commercially available products include those from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Corporation, Oriso Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group, Ltd. Among these, process oils (paraffin-based process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

[0090] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, acrylic resins, etc. Hydrogenated products of these resins can also be used.

[0091] Examples of 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, and liquid farnesene butadiene copolymers, all of which are liquid at 25°C. The terminals or main chains of these polymers may be modified with polar groups. Hydrogenated versions of these polymers can also be used.

[0092] Examples of the resins (resins in a solid state at room temperature (25°C)) that can be used in the rubber composition for the support member include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are solid at room temperature (25°C). The resins may also be hydrogenated. These may be used alone or in combination of two or more. Of these, aromatic vinyl polymers, petroleum resins, and terpene resins are preferred.

[0093] When the rubber composition for a support member contains the resin, the content of the resin is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0094] The softening point of the resin is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher. The upper limit is preferably 160° C. or lower, more preferably 130° C. or lower, and even more preferably 115° C. or lower. By keeping the softening point within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point tester.

[0095] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, it may be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically may be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, or a copolymer of styrene and another monomer.

[0096] The coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0097] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0098] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0099] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Of these, those obtained by reacting with an acid catalyst (such as novolac phenolic resin) are preferred.

[0100] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0101] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, and hydrogenated versions of these resins. Of these, DCPD resin and hydrogenated DCPD resin are preferred.

[0102] The terpene resin is a polymer containing terpene as a structural unit. Examples include polyterpene resins obtained by polymerizing terpene compounds, and aromatic-modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. Hydrogenated products of these resins can also be used.

[0103] The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0104] Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, and pinene / limonene resin, which are made from the above-mentioned terpene compounds. Among these, pinene resin is preferred. Pinene resin usually contains both α-pinene and β-pinene, which are isomers, but based on the components contained, they are classified into β-pinene resins containing β-pinene as the main component and α-pinene resins containing α-pinene as the main component.

[0105] Examples of the aromatic modified terpene resin include terpene phenol resins made from the above terpene compounds and phenolic compounds, and terpene styrene resins made from the above terpene compounds and styrene compounds. Terpene phenol styrene resins made from the above terpene compounds, phenolic compounds, and styrene compounds can also be used. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of styrene compounds include styrene and α-methylstyrene.

[0106] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component can be used. Among them, a solvent-free carboxyl-containing styrene-acrylic resin can be preferably used.

[0107] The solvent-free carboxyl group-containing styrene-acrylic resin is a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (methods described in U.S. Pat. No. 4,414,370, JP-A Nos. 59-6207, JP-B Nos. 5-58005, 1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho Annual Report TREND 2000, Vol. 3, pp. 42-45, etc.), with minimal use of auxiliary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In this specification, (meth)acrylic refers to both methacrylic and acrylic.

[0108] Examples of acrylic monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), (meth)acrylamide, (meth)acrylic acid derivatives such as (meth)acrylamide derivatives, etc. (Meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

[0109] Examples of aromatic vinyl monomer components constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0110] As the monomer component constituting the acrylic resin, other monomer components may be used in addition to (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

[0111] Examples of the plasticizer that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industry Co., Ltd.

[0112] (Other materials) The rubber composition for a support member preferably contains an antioxidant from the viewpoints of crack resistance, ozone resistance, and the like.

[0113] The antioxidant is not particularly limited, but examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and the like. Examples of suitable antioxidants include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0114] In the rubber composition for a support member, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

[0115] The rubber composition for a support member preferably contains stearic acid. The content of stearic acid in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0116] As the stearic acid, conventionally known products can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0117] The rubber composition for a support member preferably contains zinc oxide. The content of zinc oxide in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0118] As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0119] The rubber composition for a support member may contain wax. The content of the wax in the rubber composition for a support member is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0120] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically treating multiple waxes can also be used. These waxes may be used alone or in combination of two or more types.

[0121] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources, and include, for example, plant-based waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and spermaceti; mineral-based waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0122] It is preferable to compound sulfur into the rubber composition for the support member in order to form an appropriate amount of crosslinked chains in the polymer chains and to impart good performance.

[0123] In the rubber composition for a support member, the sulfur content (pure sulfur content) is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, even more preferably 1.0 parts by mass or more, and particularly preferably 1.2 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 3.0 parts by mass or less, more preferably 2.3 parts by mass or less, even more preferably 2.0 parts by mass or less, and particularly preferably 1.8 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0124] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0125] The rubber composition for the support member preferably contains a vulcanization accelerator. In the rubber composition for a support member, the content of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.7 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 3.0 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1.3 parts by mass or less, and particularly preferably 1.2 parts by mass or less. By keeping the content within the above range, the overall performance of crack growth resistance and pinch cut resistance tends to be improved.

[0126] The type of vulcanization accelerator is not particularly limited, and any commonly used accelerator can be used. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based, guanidine-based and benzothiazole-based vulcanization accelerators are preferred.

[0127] In addition to the above components, the rubber composition may contain compounding agents generally used in the tire industry, such as materials such as a mold release agent, as appropriate.

[0128] <Ply> The tire includes plies. The ply is made of, for example, a rubber composition (rubber composition for ply topping) having a sulfur content that satisfies the above (Equation 1).

[0129] (rubber component) The rubber component usable in the rubber composition for bright toppings may be, for example, the diene rubber described above. Among them, isoprene rubber, BR, and SBR are preferred, with isoprene rubber and SBR being more preferred, from the viewpoint of overall performance such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance. As the isoprene rubber, BR, and SBR, for example, those described above may be used.

[0130] In the rubber composition for bright topping, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The upper limit is preferably 95% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0131] In the rubber composition for bright topping, the BR content in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, and may be 0% by mass. By keeping the BR content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0132] The styrene content of the SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The styrene content is preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. By keeping the styrene content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved. In this specification, the styrene content is 1 It can be measured by H-NMR measurement.

[0133] The vinyl bond content of the SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The vinyl bond content is preferably 60% by mass or less, more preferably 45% by mass or less, even more preferably 25% by mass or less, particularly preferably 15% by mass or less, and most preferably 13% by mass or less. By keeping the content within the above ranges, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved. In this specification, the vinyl bond amount (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0134] In the rubber composition for glitter topping, the SBR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The upper limit is preferably 80% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. By keeping the SBR content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0135] In the rubber composition for bright topping, the total content of the isoprene-based rubber and SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. There is no particular upper limit and it may be 100% by mass. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0136] (filling material) The rubber composition for bright topping preferably contains a filler from the viewpoint of overall performance, such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance. Examples of fillers that can be used include those described above. Of these, carbon black and silica are preferred, with carbon black being more preferred.

[0137] In the rubber composition for bright topping, the content of the filler (total content of the fillers) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 65 parts by mass or less, and particularly preferably 55 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0138] The carbon black that can be used in the rubber composition for bright topping includes, for example, those mentioned above. The carbon black may be used alone or in combination of two or more kinds.

[0139] The nitrogen adsorption specific surface area (N2SA) of carbon black is 30m 2 / g or more is preferable, and 50m 2 / g or more is more preferable, and 70m 2 / g or more is more preferable. The upper limit is 200m 2 / g or less is preferable, and 100m 2 / g or less is more preferable, and 85m 2 By keeping the molecular weight within the above range, there is a tendency for the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance to be improved.

[0140] In the rubber composition for bright topping, the carbon black content is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 55 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0141] (silica) Examples of silica that can be used in the rubber composition for bright topping include those mentioned above. Silica may be used alone or in combination of two or more kinds.

[0142] When the rubber composition for glitter topping contains silica, the content thereof is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0143] (Silane coupling agent) When the rubber composition for bright topping contains silica, it is preferable to contain a silane coupling agent. Examples of the silane coupling agent that can be used include those described above. The silane coupling agent may be used alone or in combination of two or more.

[0144] In the rubber composition for glitter topping, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, per 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0145] (plasticizer) A plasticizer may be blended into the rubber composition for bright topping. Examples of the plasticizer that can be used include those described above. These may be used alone or in combination of two or more.

[0146] In the rubber composition for glitter topping, the content of the plasticizer (total amount of plasticizer) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0147] The liquid plasticizer (a plasticizer that is in a liquid state at room temperature (25°C)) that can be used in the rubber composition for bright topping is not particularly limited, and for example, the aforementioned ones can be used. These may be used alone or in combination of two or more kinds.

[0148] In the rubber composition for glitter topping, the content of the liquid plasticizer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved. The oil content is also preferably in a similar range.

[0149] As the resin (resin in a solid state at room temperature (25°C)) that can be used in the rubber composition for bright topping, for example, the above-mentioned ones can be used. These may be used alone or in combination of two or more kinds.

[0150] When the rubber composition for bright topping contains the resin, the content of the resin is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. The lower limit of the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0151] (hardened resin) From the viewpoint of overall performance such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance, the rubber composition for bright topping preferably contains a cured resin. The cured resin is a resin that has curing (crosslinking) properties, and examples thereof include resorcinol resin (condensation product), modified resorcinol resin (condensation product), cresol resin, modified cresol resin, phenol resin, and modified phenol resin. Among these, modified resorcinol resin and modified phenol resin are preferred.

[0152] Examples of resorcinol resins include resorcinol-formaldehyde condensates. Examples of modified resorcinol resins include resorcinol resins in which some of the repeating units have been alkylated. Examples of cresol resins include cresol-formaldehyde condensates. Examples of modified cresol resins include cresol resins in which the terminal methyl groups have been modified with hydroxyl groups, and cresol resins in which some of the repeating units have been alkylated. Examples of phenolic resins include phenol-formaldehyde condensates. Examples of modified phenolic resins include resins modified with cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, melamine, etc.

[0153] In the rubber composition for ply topping, the content of the cured resin is preferably at least 0.5 parts by mass, more preferably at least 0.8 parts by mass, and even more preferably at least 1.0 part by mass per 100 parts by mass of the rubber component, from the viewpoint of overall performance, such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance. The upper limit of the content is preferably at most 5.0 parts by mass, more preferably at most 3.0 parts by mass, and even more preferably at most 2.0 parts by mass. By keeping the content within the above range, improved durability is likely achieved by reducing the hardness difference. While the reason for this effect is not entirely clear, it is presumed that reducing the hardness difference between the ply and the support member reduces local stress concentration at the interface, improving the reinforcement at the interface against large deformation. The total content of the resorcinol resin (condensate), modified resorcinol resin (condensate), cresol resin, modified cresol resin, phenolic resin, and modified phenolic resin, as well as the content of the resorcinol resin (condensate), are also preferably within the same range.

[0154] (hardening agent) The rubber composition for bright topping preferably contains, in addition to the cured resin, at least one methylene donor selected from the group consisting of a partial condensate of hexamethoxymethylolmelamine (HMMM) and a partial condensate of hexamethylolmelamine pentamethyl ether (HMMPME). Such a methylene donor functions as a curing agent. Note that the cured resin and the curing agent are materials that have curing and crosslinking properties and do not fall under the category of the plasticizers described above.

[0155] In the rubber composition for glitter topping, the content of the methylene donor (total amount of HMMM partial condensate and HMMPME partial condensate) is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. By setting the lower limit of the content within the above range, overall performance tends to be improved in vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance.

[0156] (Other materials) The rubber composition for bright toppings may contain other materials such as the antioxidant, stearic acid, zinc oxide, wax, and release agent. For example, the materials listed above can be used as these materials. The content of these materials can also be within the same range.

[0157] The rubber composition for bright topping preferably contains sulfur. As the sulfur, the above-mentioned sulfur compounds can be used.

[0158] In the rubber composition for bright topping, the sulfur content (pure sulfur amount) is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, even more preferably 3.5 parts by mass or more, and particularly preferably 3.7 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 8.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.5 parts by mass or less, and particularly preferably 4.2 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0159] The rubber composition for bright topping preferably contains a vulcanization accelerator, and the vulcanization accelerators described above can be used.

[0160] In the rubber composition for glitter topping, the content of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.7 parts by mass or more, even more preferably 0.8 parts by mass or more, and particularly preferably 0.9 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 3.0 parts by mass or less, more preferably 1.6 parts by mass or less, even more preferably 1.4 parts by mass or less, and particularly preferably 1.3 parts by mass or less. By keeping the content within the above range, the overall performance of vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance tends to be improved.

[0161] From the viewpoint of the overall performance of the tire, such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance, it is preferable that the sulfur content of the support member (TSs (mass%)) and the sulfur content of the bright topping rubber (TSp (mass%)) satisfy the following (Equation 2): (Equation 2) TSp-TSs<2.0 By satisfying formula 2, the hardness difference is reduced, resulting in improved durability. The reason for this effect is not entirely clear, but it is presumed that by reducing the difference in sulfur concentration between the support member and the ply, co-vulcanization at the interface is strengthened, improving the reinforcement at the interface as well.

[0162] From the viewpoint of overall performance such as vulcanization adhesion to the support member, adhesion to the textile cord, and pinch cut resistance, TSp-TSs is preferably 1.7% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.3% by mass or less, and particularly preferably 1.2% by mass or less. There is no particular lower limit, but 0.1% by mass or more is preferred, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 0.7% by mass or more is preferred.

[0163] The ply (carcass) can be produced by a conventionally known method, for example, by stretching a plurality of ply cords (carcass cords) and arranging them in parallel, and then topping (covering) the top and bottom of the ply cords with an unvulcanized ply topping rubber composition (carcass topping rubber composition). Note that conventionally known ply cords can be used, such as textile cords (fiber cords) made of organic fibers such as polyester, steel cords made of steel, etc.

[0164] The rubber composition for support members and the rubber composition for bright toppings can be produced by known methods, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0165] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

[0166] A tire is manufactured by a conventional method using the rubber composition. That is, the rubber composition for the support member and the rubber composition for the ply topping, which contain the above-mentioned components, are extruded in the unvulcanized state to match the shapes of the support member and the ply, and then molded together with other tire components 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.

[0167] Examples of the tire include pneumatic tires and non-pneumatic tires. Among these, pneumatic tires are preferred. The tire can be used for passenger car tires, large passenger car tires, large SUV tires, heavy-duty tires for trucks, buses, etc., light truck tires, motorcycle tires, racing tires (high-performance tires), etc. Furthermore, each tire may be a run-flat tire equipped with a side reinforcing layer. Among these, the tire can be suitably used for passenger car tires, large passenger car tires, large SUV tires, and light truck tires.

[0168] 1 shows a partial cross-sectional view of a tire according to one embodiment of the present invention, although the present invention is not limited to this embodiment.

[0169] The pneumatic tire shown in FIG. 1 includes a tread portion 1, sidewalls 4, clinches 5, bead portions 6, a ply 3 that passes radially inward of the tire between the tread portion 1 and the sidewalls 4 and is disposed along the bead portions 6, and a breaker layer 2 that is disposed between the tread portion 1 and the ply 3. Both ends of the ply 3 are folded back and secured along a pair of bead cores 7 disposed in the bead portions 6, and chafers 8 are disposed at the locations of the ply 3 that contact the rim R. The rim R abuts against the clinches 5, which are connected to the ply 3 and the sidewalls 4. For example, one embodiment of the tire may include a tire in which the sidewalls 4 are used as support members. [Example]

[0170] The various chemicals used in the examples and comparative examples will be collectively described below. NR:TSR20 BR: BR150B (cis content 97% by mass) manufactured by Ube Industries, Ltd. SBR: JSR1502 (styrene content 25.2% by mass) manufactured by JSR Corporation Carbon black N220: Diablack N220 (N2SA114m) manufactured by Mitsubishi Chemical Corporation 2 / g) Carbon black N330: Show Black N330 (N2SA78m) manufactured by Cabot Japan Co., Ltd. 2 / g) Carbon black N550: Diablack N550 (N2SA40m) manufactured by Mitsubishi Chemical Corporation 2 / g) Polyamide polyether elastomer: UBESTA XPA 9040X1 (melting point 130°C) manufactured by Ube Industries, Ltd. Acid-modified polyolefin: Admer HE810 (maleic anhydride-modified polyethylene, the main chain of which is an ethylene homopolymer and is modified with maleic anhydride. Maleic anhydride is bonded to the main chain as a side chain. Melting point: 130°C, density: 960 kg / m 3 ) Oil: Idemitsu Kosan Co., Ltd. Diana Process NH-70S (aromatic process oil) Antioxidant 6C: Nocrac 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant RD: Nocrac 224 (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Curing resin: Sumikanol 620 (modified resorcinol resin (modified resorcinol-formaldehyde condensate)) manufactured by Taoka Chemical Co., Ltd. Hardener: Sumikanol 507A manufactured by Sumitomo Chemical Co., Ltd. (modified etherified methylol melamine resin (partial condensate of hexamethylol melamine pentamethyl ether (HMMPME)), containing 35% by mass of silica and oil) Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Ginrei R manufactured by Toho Zinc Co., Ltd. Sulfur 1: Seimisulfur manufactured by Nippon Kanretsu Kogyo Co., Ltd. (Insoluble sulfur containing 60% or more insoluble matter due to carbon disulfide, 10% oil by mass; the values ​​in the table are pure sulfur amounts) Sulfur 2: Crystex HSOT20 manufactured by Flexis Co., Ltd. (insoluble sulfur containing 80% by mass of sulfur and 20% by mass of oil; the values ​​in the table are pure sulfur amounts) Vulcanization accelerator DM: Noccela DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator NS: Noccela NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0171] <Examples and Comparative Examples> (Rubber composition for support member) According to the formulation shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7 L Banbury mixer to obtain a kneaded product (base kneading step). Next, sulfur and vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 3 minutes at 105°C using an open roll to obtain an unvulcanized rubber composition for a support member (final kneading step). The obtained unvulcanized rubber composition for a support member was press-vulcanized at 170°C for 12 minutes to obtain a vulcanized rubber composition for a support member.

[0172] (Rubber composition for bright topping) According to the formulation shown in Table 2, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7 L Banbury mixer to obtain a kneaded product (base kneading step). Next, sulfur and vulcanization accelerator were added to the kneaded product, and the mixture was kneaded for 3 minutes at 105°C using an open roll to obtain an unvulcanized rubber composition for bright topping (finish kneading step).

[0173] (Production of test tires) Using the unvulcanized rubber compositions for each support member and each unvulcanized rubber composition for each ply obtained according to the specifications in Table 3, the unvulcanized rubber compositions for support members (unvulcanized rubber compositions for sidewalls) were extruded into the shape of a sidewall, which was then bonded together with other tire components in a tire building machine and vulcanized for 12 minutes at 170°C to obtain test tires (size: 195 / 65R15) (crosslinking step). During molding, the unvulcanized rubber compositions for plies obtained were formed into a sheet, which was then coated with fiber cord (1670 dtex / 2-PET) and molded into the shape of the ply.

[0174] The vulcanized rubber compositions for support members and test tires thus prepared were used to carry out the following evaluations. The results of the physical properties and evaluations are shown in Tables 1 to 3. Note that Comparative Example 3 was used as the reference comparative example in Table 3.

[0175] (sulfur content) Test specimens were prepared by taking sidewall rubber and ply-topping rubber from the sidewall and ply of each test tire, and the sulfur content (mass%) in the test specimens was calculated using the oxygen combustion flask method in accordance with JIS-K6233:2016 (TSs, TSp).

[0176] (Crack growth resistance (supporting member)) Using each vulcanized rubber composition for support members, a rubber slab sheet measuring 1 mm x 50 mm x 20 mm was prepared. The sample was cut with a razor to a width of 2 mm to create an initial crack, and repeated strain was applied in the long side direction (perpendicular to the cutting direction). The strain rate was 5%, the frequency was 5 Hz, and the sample temperature was 70°C. The initial crack growth rate dc / dn (m / cycle) was measured from the time of repeated strain application until the crack growth length reached approximately 1 mm. The data was an average of N=4. The initial crack growth rate of the reference comparative example was set to 100 and indexed. A larger index indicates more suppressed crack growth and better crack growth resistance.

[0177] (Pinch cut resistance) Each test tire was mounted on a testing machine, a load was applied to the tire, and the buttress region and bead region of the tire were clamped together, and the load-strain curve was measured. This measurement ended when the cord contained in the ply (carcass) broke. Based on the obtained curve, the integrated value of the load per unit strain (tire fracture energy) was calculated. The results were indexed, with the reference comparative example being set at 100. The higher the value, the better the pinch cut resistance.

[0178] [Table 1]

[0179] [Table 2]

[0180] [Table 3]

[0181] As can be seen from the table, the tires of the examples in which the support member contained polyamide polyether elastomer and the polyamide polyether elastomer content (PA (mass%)) in the support member and the sulfur content (TSp (mass%)) of the bright topping rubber satisfied the above (Equation 1) were excellent in overall crack growth resistance and pinch cut resistance (expressed as the sum of two indices: crack growth resistance (support member) and pinch cut resistance). [Explanation of symbols]

[0182] 1 Tread section 2 Breaker layer 3 ply 4 Sidewall 5 Clinch 6 Bead section 7 Bead Core 8 Chafer R rim

Claims

1. A tire having a support member comprising a polyamide polyether elastomer, the polyamide polyether elastomer content (PA (mass%)) in the support member and the sulfur content (TSp (mass%)) of the bright topping rubber satisfy the following (Equation 1), (Formula 1) PA-TSp<15.0 The PA is 4.5% by mass or more and 16.0% by mass or less, The TSp is 1.5% by mass or more and 3.0% by mass or less, The rubber composition for bright topping has a sulfur content (pure sulfur amount) of 3.7 parts by mass or more per 100 parts by mass of the rubber component, The rubber composition for a support member of a tire has a silica content of 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component.

2. The tire according to claim 1, wherein the PA (mass%) and the TSp (mass%) satisfy the following formula: PA-TSp≦12.0

3. The tire according to claim 1 or 2, wherein the PA (mass %) satisfies the following formula: 6.0≦PA≦11.0

4. The tire according to any one of claims 1 to 3, wherein the TSp (mass%) satisfies the following formula: 1.7≦TSp≦2.6

5. 5. The tire according to claim 1, wherein the support member contains 5 to 30 parts by mass of the polyamide polyether elastomer per 100 parts by mass of a rubber component.

6. 6. The tire according to claim 1, wherein the support member contains 3 to 20 parts by mass of acid-modified polyolefin per 100 parts by mass of the rubber component.

7. The support member has an isoprene-based rubber content of 20 to 60% by mass and a butadiene rubber content of 40 to 80% by mass relative to 100% by mass of the rubber component, The tire according to any one of claims 1 to 6, wherein the bright topping rubber has an isoprene-based rubber content of 50 to 85 mass% and a styrene-butadiene rubber content of 15 to 50 mass% based on 100 mass% of the rubber component.

8. The support member has a nitrogen adsorption specific surface area of ​​55 m per 100 parts by mass of the rubber component. ２ The tire according to any one of claims 1 to 7, wherein the content of carbon black is 10 to 60 parts by mass / g or less.

9. 9. The tire according to claim 1, wherein the bright topping rubber contains 0.5 to 5.0 parts by mass of cured resin per 100 parts by mass of the rubber component.

10. The tire according to any one of claims 1 to 9, wherein the sulfur content (TSs (mass%)) of the support member and the sulfur content (TSp (mass%)) of the bright topping rubber satisfy the following (Equation 2): (Formula 2) TSp−TSs<2.0

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