JP2010167985A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving riding comfort while keeping the durability of run-flat traveling at an equivalent level to a conventional one or higher in the pneumatic tire of which the side reinforcement member enabling run-flat traveling is configured of thermoplastic resin or a thermoplastic elastomer composition. <P>SOLUTION: A side reinforcement member 10 with a crescent shape enabling run-flat traveling is disposed at a side wall 2, and the side reinforcement member 10 is composed of the thermoplastic resin or the thermoplastic elastomer composition formed by mixing the thermoplastic resin composition with an elastomer element to configure the pneumatic tire. A storage modulus of the side reinforcement member 10 at the outer side 10A and/or the inner side 10B in the tire diametrical direction is lower than that at the center side 10C in the tire diametrical direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire provided with a side reinforcing member that enables run-flat running and that improves riding comfort.

  Conventionally, as a pneumatic tire with run-flat running performance that allows the vehicle to run even after the air in the tire has escaped due to puncture etc., it has a crescent-shaped cross section that allows run-flat running on the sidewall part There is known a tire in which a side reinforcing member is arranged and the side reinforcing member is made of a thermoplastic elastomer or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component (for example, see Patent Document 1).

  As described above, by forming the side reinforcing member from the thermoplastic resin or the thermoplastic elastomer composition instead of the high-hardness rubber, there is an advantage that the run-flat durability can be enhanced by increasing the rigidity of the sidewall portion. On the other hand, however, there is a problem that the ride comfort during normal driving is greatly reduced due to the increased rigidity of the sidewall portion.

JP 10-35232 A

  An object of the present invention is to maintain a durability at the time of run-flat running at a level equal to or higher than that of a conventional tire in which a side reinforcing member that enables run-flat running is composed of a thermoplastic resin or a thermoplastic elastomer composition. An object of the present invention is to provide a pneumatic tire capable of improving ride comfort.

  In the pneumatic tire of the present invention that achieves the above object, a side reinforcing member having a crescent-shaped cross section that enables run-flat running is disposed in a sidewall portion, and the side reinforcing member is made of a thermoplastic resin or a thermoplastic resin component and an elastomer. In a pneumatic tire composed of a thermoplastic elastomer composition blended with components, the storage elastic modulus of the side reinforcing member is lower in the tire radial direction outer side and / or the inner side than the tire radial direction central side.

  According to the above-described present invention, the side wall portion can be easily bent by partially reducing the storage elastic modulus of the side reinforcing member, so that riding comfort during normal traveling can be improved. On the other hand, in a side reinforcing member having a crescent-shaped cross section made of a thermoplastic resin or a thermoplastic elastomer composition, the outer side in the tire radial direction located on the end side that is gradually thinned and easily broken by repeated deformation during run-flat running and By reducing the inner storage elastic modulus, the occurrence of the breakage can be suppressed, so that the durability during run-flat running can be maintained at the same level or higher.

It is a fragmentary sectional view showing one embodiment of the pneumatic tire of the present invention. It is an expanded sectional view showing other examples of a side reinforcement member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an embodiment of the pneumatic tire of the present invention, wherein 1 is a tread portion, 2 is a bead portion, and 3 is a sidewall portion. Left and right sidewall portions 2 extend from the left and right bead portions 3 outward in the tire radial direction, and a tread portion 1 is provided between the left and right sidewall portions 2.

  Two carcass layers 4 are extended between the right and left bead portions 3 on the tire inner side, and both end portions thereof are inserted from the inner side in the tire axial direction so as to sandwich the bead filler 6 around the bead core 5 embedded in the bead portion 3. It is folded outside. Two belt layers 7 are provided on the outer peripheral side of the carcass layer 4 of the tread portion 1. A plurality of belt cover layers 8 for protecting the belt layer 7 are disposed on the outer peripheral side of the belt layer 7.

  An inner liner layer 9 that functions as an air permeation preventive layer is disposed inside the carcass 4. Both side wall portions 2 are provided with side reinforcing members 10 between the inner carcass layer 4 and the inner liner layer 9 in which a tire meridian cross-sectional shape for enabling run-flat running is formed in a substantially crescent shape. It has been. The side reinforcing member 10 is annularly extended along the tire circumferential direction, the outer peripheral end thereof extends to the inner peripheral side of the belt layer 7, and the inner peripheral end is the inner peripheral side of the bead filler 6 in a side view. It extends to the position that overlaps the part.

  The side reinforcing member 10 is made of a thermoplastic elastomer or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, and is located on the tire radial direction outer side portion 10A located on the outer peripheral end side and on the inner peripheral end side. The storage elastic modulus of the tire radial inner portion 10B is different from the storage elastic modulus of the tire radial central side portion 10C located therebetween, and the storage elastic modulus of the tire radial outer portion 10A and the inner portion 10B is set to the tire radial central side. It is lower than the part 10C.

  The side reinforcing member 10 having such a configuration is configured by winding the strip material S in the tire circumferential direction. For example, when the side reinforcing member 10 is made of a thermoplastic elastomer composition, a strip material S made of two types of thermoplastic elastomer compositions having different storage elastic moduli is used. The storage elastic modulus can be adjusted by adjusting the amount of the elastomer component when the same thermoplastic resin component is contained, and the storage elastic modulus can be lowered and increased by increasing the amount. A strip material having a higher storage elastic modulus (lower elastomer component) is wound in the tire circumferential direction to form a tire radial direction central side portion 10C, and a strip having a lower storage elastic modulus (one having a higher elastomer component) is formed. The material S is wound in the tire circumferential direction to constitute a tire radial direction outer portion 10A and an inner portion 10B.

  Alternatively, three strip materials S made of a thermoplastic elastomer composition having the same storage elastic modulus are used, and one strip material S is wound in the tire circumferential direction to form the tire radial center side portion 10C, and the rest Each of the strip materials S may be wound in the tire circumferential direction with a rubber layer interposed therebetween to constitute the tire radial direction outer portion 10A and the inner portion 10B. The remaining one strip material S is made of a thermoplastic resin instead of the thermoplastic elastomer composition, and is wound around the tire circumferential direction with a rubber layer interposed therebetween. You may form the tire radial direction outer side part 10A and the inner side part 10B in which a storage elastic modulus becomes low.

  As the rubber of the rubber layer to be interposed, rubber having a storage elastic modulus at 20 ° C. of 0.03 to 0.90 MPa is particularly preferable from the viewpoint of ride comfort. As a blending of such a rubber composition, a diene rubber compound in which 20 parts by weight or more of epoxidized natural rubber (epoxidation rate 50 mol%) is blended with 100 parts by weight of the raw rubber can be preferably exemplified. When importance is attached to heat resistance, a rubber having a tan δ at 60 ° C. of 0.03 to 0.20 is preferable.

  When the side reinforcing member 10 is made of a thermoplastic resin, a strip material S made of two types of thermoplastic resins having different storage elastic moduli is used, and the strip material made of a thermoplastic resin having a higher storage elastic modulus is used for the tire circumference. 10C of the tire radial direction center side part is wound by winding in the direction, and a strip material made of a thermoplastic resin having a lower storage elastic modulus is wound in the tire circumferential direction so that the tire radial direction outer part 10A and the inner part 10B are respectively Constitute.

  Alternatively, a strip material S made of a thermoplastic resin and a strip material S made of a thermoplastic elastomer composition having a lower storage elastic modulus are used, and the strip material made of a thermoplastic resin is wound around the tire in the tire circumferential direction. The direction center side portion 10C may be configured, and a strip material made of a thermoplastic elastomer composition may be wound in the tire circumferential direction to configure the tire radial direction outer portion 10A and the inner portion 10B, respectively.

  According to the above-described present invention, the side wall portion 2 can be easily bent by partially lowering the storage elastic modulus of the side reinforcing member 10 having a crescent-shaped cross section, so that the riding comfort during normal driving is improved. Is possible. On the other hand, in the side reinforcing member 10 made of a thermoplastic resin or a thermoplastic elastomer composition, the tire radial outer side portion 10A and the inner side portion are located on the end side that is gradually thinned and easily broken by repeated deformation during run flat running. By reducing the storage elastic modulus of 10B, the fragile end side becomes easier to follow the deformation than before, so that the breakage can be suppressed, and the durability during run-flat running can also be improved.

  In the present invention, the ratio of the storage elastic modulus of the tire radial direction outer side portion 10A and the tire radial direction central side portion 10C (storage elastic modulus of the tire radial direction outer side portion 10A / storage elastic modulus of the tire radial direction central side portion 10C) and the tire The ratio of the storage elastic modulus of the radially inner portion 10B and the tire radial center side portion 10C (the storage elastic modulus of the tire radial inner portion 10B / the storage elastic modulus of the tire radial center side portion 10C) is 0.25 respectively. It is good to be in the range of ~ 0.75. If the storage modulus ratio is less than 0.25, sufficient run-flat durability cannot be ensured. When the ratio of storage elastic modulus is larger than 0.75, a sufficient effect of suppressing fracture cannot be obtained.

  The storage elastic modulus of the thermoplastic resin or thermoplastic elastomer composition used for the side reinforcing member 10 can be in the range of 5 to 1200 MPa. If the storage elastic modulus is lower than 5 MPa, sufficient run-flat durability cannot be ensured. When the storage elastic modulus is higher than 1200 MPa, the rigidity of the side reinforcing member 10 becomes excessively high, so that it is easily broken and causes a tire failure. Preferably, the range is 15 to 500 MPa.

  The tan δ at 60 ° C. of the thermoplastic resin and the thermoplastic elastomer composition constituting the side reinforcing member 10 is preferably in the range of 0.04 to 0.3 from the viewpoint of heat resistance.

  The range of the tire radial direction center side portion 10C is the total length of the side reinforcing member 10 (straight line SA) from the midpoint C1 of the straight line SA connecting the outer peripheral end 10x and the inner peripheral end 10y of the side reinforcing member 10 to both sides in the linear extending direction. The total length can be within a range sandwiched by perpendicular lines X1 and X2 drawn from the points C2 and C3 of at least 15% of the EL to the straight line SA. At most, in the range sandwiched by perpendicular lines X3 and X4 drawn from the points C4 and C5 to the straight line SA at 35% of the total length (the total length of the straight line SA) EL of the side reinforcing member 10 on both sides in the straight line extending direction from the middle point C1. can do. The range of the tire radial direction outer portion 10A can be a range from the outer peripheral end 10x to the point C4 that is at least 15% of the total length EL of the side reinforcing member 10. The range from the outer peripheral end 10x to the point C2 that is 35% of the total length EL of the side reinforcing member 10 can be set at the maximum. The range of the tire radial direction inner portion 10B can be a range from the inner peripheral end 10y to the point C5 that is at least 15% of the total length EL of the side reinforcing member 10. The range from the inner peripheral end 10y to the point C3 that is 35% of the total length EL of the side reinforcing member 10 can be maximized. The region sandwiched between the perpendicular lines X1 and X3 may have a configuration in which the storage elastic modulus of the tire radial direction center side portion 10C and the tire radial direction outer side portion 10A are mixed. Further, the region sandwiched between the perpendicular lines X2 and X4 may have a configuration in which the storage elastic modulus of the tire radial direction center side portion 10C and the tire radial direction inner side portion 10B are mixed.

  The side reinforcing member 10 preferably has a storage elastic modulus that gradually decreases toward the outer side and the inner side in the tire radial direction. A preferred example is shown in FIG. The side reinforcing member 10 in FIG. 2 includes a center portion 10C in the tire radial direction and a center portion 10C1 and side portions 10C2 that are less elastic than the center portion 10C1 on both sides in the tire radial direction. The portion 10B is composed of a first portion 10A1, 10B1, a second portion 10A2, 10B2, and a third portion 10A3, 10B3, each of which is divided into three in the tire radial direction. The first portions 10A1 and 10B1 adjacent to the central portion 10C in the tire radial direction have a lower storage elastic modulus than the side portions 10C2 but have a higher storage elastic modulus than the adjacent second portions 10A2 and 10B2, and are located at the end. The storage elastic modulus of the three portions 10A3 and 10B3 is the lowest, and the side reinforcing member 10 has the storage elastic modulus of the center portion 10C1, the side portion 10C2, the first portions 10A1, 10B1, the second portions 10A2, 10B2, and the third portion. It becomes lower gradually in order of 10A3 and 10B3. By gradually lowering the storage elastic modulus in this way, stress concentration at the boundary portion where the storage elastic modulus changes can be relaxed, and durability during run-flat running can be further increased.

  In the side reinforcing member 10, the boundary line between the tire radial direction center side part 10C and the tire radial direction outer side part 10A and the boundary line between the tire radial direction center side part 10C and the tire radial direction inner side part 10B are shown in FIG. Instead of the state, it may extend obliquely (oblique with respect to the straight boundary line shown in FIG. 2). In the illustrated side reinforcing member 10, the position where the thickness is maximum is located at the center in the longitudinal direction, but the side reinforcing member 10 may have the maximum thickness at a position shifted vertically from there.

  In the pneumatic tire having the side reinforcing member 10 as described above, it is preferable that the side reinforcing member 10 is formed in advance by the thin-film strip material S and is attached when the green tire is formed. Preferably, the side reinforcing member 10 that is preliminarily formed by winding the strip material S is placed in a mold that can be molded so as to have a final member shape, and is further heated to further stabilize the shape. .

  When winding the strip material S, it is preferable to appropriately select the winding tension (reducing the winding tension toward the outer side in the radial direction), and bonding between the wound strip materials S can be performed by vulcanization bonding or strip material in advance. An adhesive may be applied to the surface of S and adhered by the adhesive.

  The strip material S described above can have a width of 5 to 30 mm and a thickness of 0.5 to 3.0 mm.

  In the present invention, the thermoplastic resin used for the side reinforcing member 10 is, for example, a polyamide resin [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 ( MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer] and their N-alkoxyalkylated products, for example, methoxymethylated products of nylon 6, nylon 6 / 610 copolymer methoxymethylated product, nylon 612 methoxymethylated product, polyester Resin (for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, Aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) Acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resins [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl Resin (for example, vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDVC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, chloride) Vinylidene / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer (ETFE)], cellulosic resin [for example, cellulose acetate, cellulose acetate butyrate], fluorine resin [for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer], an imide resin [for example, aromatic polyimide (PI)] and the like can be preferably used.

  The thermoplastic elastomer composition can be constituted by mixing an elastomer component with the above-described thermoplastic resin component. Examples of the elastomer used include diene rubbers and hydrogenated products thereof [for example, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene bradiene rubber (SBR), bradiene rubber (BR, high Cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubber [eg, ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), Butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [for example, Br-IIR, CI-IIR, bromine of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydride Rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid-modified chlorinated polyethylene rubber (M-CM)], silicone rubber [eg, methyl vinyl silicone rubber, dimethyl silicone rubber, Methyl phenyl vinyl silicon rubber], sulfur-containing rubber (for example, polysulfide rubber), fluorine rubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene) Rubbers], thermoplastic elastomers (for example, styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, polyamide elastomers) and the like can be preferably used.

  When the above-mentioned specific thermoplastic resin component and the elastomer component are different in compatibility, they can be made compatible by using a suitable compatibilizer as the third component. By mixing the compatibilizer with the blend system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the particle size of the rubber forming the dispersion layer becomes fine. It will be expressed more effectively. As such a compatibilizing agent, generally a copolymer having a structure of both or one of the thermoplastic resin and the elastomer component, or an epoxy group, a carbonyl group, a halogen group, which can react with the thermoplastic resin or the elastomer component, The structure of a copolymer having an amino group, an oxazoline group, a hydroxyl group and the like can be taken. These may be selected according to the kind of the thermoplastic resin and the elastomer component to be mixed, but those usually used include styrene / ethylene butylene block copolymer (SEBS) and its maleic acid modified product, EPDM, EPM. EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid modified product, styrene / maleic acid copolymer, reactive phenoxin and the like. The amount of the compatibilizing agent is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer component).

  The composition ratio between the specific thermoplastic resin component (A) and the elastomer component (B) in the case of blending the thermoplastic resin and the elastomer is not particularly limited, and may be determined appropriately depending on the storage elastic modulus and the cross-sectional area of the strip material. A preferred range is a weight ratio of 90/10 to 30/70.

  In addition to the above essential polymer component, the polymer composition according to the present invention may be mixed with other polymers such as the above-described compatibilizer polymer within a range that does not impair the necessary characteristics of the tire polymer composition of the present invention. it can. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the molding processability of the material, to improve heat resistance, to reduce costs, etc. Examples of the material used include polyethylene (PE) polypropylene (PP), polystyrene (PS), ABS, SBS, polycarbonate (PC) and the like. In the polymer composition according to the present invention, fillers (calcium carbonate, titanium oxide, alumina, etc.), carbon black, white carbon and other reinforcing agents generally blended in polymer blends, softeners, plasticizers, Processing aids, pigments, dyes, anti-aging agents, and the like can be optionally added as long as the above Young's modulus requirements are not impaired.

  The elastomer component can also be dynamically vulcanized when mixed with a thermoplastic resin. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time), etc. when dynamically vulcanizing may be appropriately determined according to the composition of the elastomer component to be added, and are not particularly limited. .

  A general rubber vulcanizing agent (crosslinking agent) can be used as the vulcanizing agent. Specific examples of the sulfur vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide, and the like. About 4 phr [phr: parts by weight per 100 parts by weight of rubber component (polymer)] can be used.

  Organic peroxide vulcanizing agents include benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxide). Oxy) hexane, 2,5-dimethylhexane-2,5-di (peroxylbenzoate), etc. are exemplified, and for example, about 1 to 20 phr can be used.

  Furthermore, examples of the phenol resin-based vulcanizing agent include bromides of alkyl phenol resins, mixed crosslinking systems containing halogen donors such as tin chloride and chloroprene, and alkyl phenol resins. For example, about 1 to 20 phr is used. Can do. In addition, zinc white (about 5 phr), magnesium oxide (about 4 phr), risurge (about 10-20 phr), p-quinonedioxime, p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone, poly-p- Examples thereof include dinitrosobenzene (about 2 to 10 phr) and methylenedianiline (about 0.2 to 10 phr).

  Moreover, you may add a vulcanization accelerator as needed. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate, thiourea, etc. About 2 phr can be used. Specifically, as the aldehyde / ammonia vulcanization accelerator, hexamethylenetetramine and the like, as the guanidinium vulcanization accelerator, diphenyl guanidine, etc., as the thiazole vulcanization accelerator, dibenzothiazyl disulfide ( DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt and the like, sulfenamide vulcanization accelerators include cyclohexylbenzothiazylsulfenamide (CBS), N-oxydiethylenebenzothiazyl-2- As thiuram vulcanization accelerators such as sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, 2- (thymolpolynyldithio) benzothiazole, tetramethylthiuram disulfide (TMTD), tetraethyl Thiuram disulfide, tetrame Examples of dithioate-based vulcanization accelerators such as lutiuram monosulfide (TMTM) and dipentamethylene thiuram tetrasulfide include Zn-dimethyldithiocarbamate, Zn-diethyldithiocarbamate, Zn-di-n-butyldithiocarbamate, Zn -Ethyl phenyl dithiocarbamate, Te-diethyl dithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, pipecoline pipecolyldithiocarbamate, etc. Examples of thiourea vulcanization accelerators include ethylenethiourea, diethylthiourea be able to.

Moreover, as a vulcanization | cure acceleration | stimulation adjuvant, the general rubber adjuvant can be used together, for example, zinc white (about 5 phr), stearic acid, oleic acid, and these Zn salts (about 2-4 phr) Etc. can be used. A method for producing a thermoplastic elastomer composition is a method in which a thermoplastic resin component and an elastomer component (unvulcanized product in the case of rubber) are previously melt-kneaded with a twin-screw kneading extruder or the like to form a continuous phase (matrix). By dispersing the elastomer component as a dispersed phase (domain) in the plastic resin. When vulcanizing the elastomer component, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer component. Further, various compounding agents (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading, but are preferably mixed in advance before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer component is not particularly limited, and a screw extruder, a kneader, a Banbury mixer, a biaxial kneading extruder, or the like can be used. Among them, it is preferable to use a twin-screw kneading extruder for kneading the thermoplastic resin and the elastomer component and for dynamic vulcanization of the elastomer component. Further, two or more types of kneaders may be used and kneaded sequentially. As conditions for melt-kneading, the temperature may be equal to or higher than the temperature at which the thermoplastic resin melts. Moreover, it is preferable that the shear rate at the time of kneading | mixing is 1000-7500Sec < ^-1 >. The entire kneading time is from 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after addition is preferably from 15 seconds to 5 minutes. The polymer composition produced by the above method may be formed into a desired strip shape by a general thermoplastic resin molding method such as injection molding or extrusion molding.

  The strip material S thus obtained has a structure in which the elastomer component (B) is dispersed as a discontinuous phase in the matrix of the thermoplastic resin (A). By taking such a structure, the side reinforcing member 10 can be provided with sufficient flexibility and sufficient rigidity due to the effect of the resin layer as a continuous phase, and at the time of molding, regardless of the amount of the elastomer component, Molding processability equivalent to that of a plastic resin can be obtained.

  Adhesion with the tire component adjacent to the side reinforcing member 10 is performed by applying an adhesive in which a polymer such as a normal rubber, phenol resin, acrylic copolymer, isocyanate, or the like and a crosslinking agent are dissolved in a solvent to the bead filler. , Adhesion by heat and pressure during vulcanization molding, or stripping adhesive resin such as styrene butadiene styrene copolymer (SBS), ethylene ethyl acrylate (EEA), styrene ethylene butylene block copolymer (SEBS) There is a method in which a multilayer laminate is prepared by co-extrusion or laminating with a material and bonded to an adjacent tire constituent member during vulcanization. Examples of the solvent-based adhesive include phenol resin (Chemlock 220, Rhode), chlorinated rubber (Chemlock 205, Chemlock 234B), isocyanate (Chemlock 402), and the like.

  In the present invention, it is preferable to lower the storage elastic modulus of the tire radial direction outer side portion 10A and the inner side portion 10B of the side reinforcing member 10 as in the above-described embodiment. Either one may have a lower storage elastic modulus as described above, thereby improving ride comfort while maintaining durability during run-flat running at the same level or higher.

  The storage modulus referred to in the present invention is measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under conditions of a temperature of 20 ° C., a frequency of 20 Hz, a static strain of 10%, and a dynamic strain of ± 2%. The tan δ of 60 ° C. referred to in the present invention is measured using the same viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of temperature 60 ° C., frequency 20 Hz, static strain 10%, and dynamic strain ± 2%. To do.

  The tires of the present invention 1 to 3 and the conventional tire were manufactured with a tire size of 255 / 40R17, a common tire structure in FIG. 1, and different side reinforcement members.

  The side reinforcing member in the tire 1 of the present invention is a thermoplastic elastomer composition (using nylon 11 [Atchem Corp./Rilsan BMNO TL] as a thermoplastic resin component and Br-IPMS [EXXON Corp./EXXPRO 89-4] as an elastomer component) The ratio of the thermoplastic resin component and the elastomer component in the tire radial center side portion is 55:45 (storage elastic modulus 100 MPa), and the thermoplastic resin component and the elastomer component in the tire radial outer portion and the inner portion The ratio is 40:60 (storage elastic modulus 50 MPa).

  The side reinforcing member in the tire 2 of the present invention has a thermoplastic elastomer composition (nylon 11 [Atchem Corp./Rilsan BMNO TL] as the thermoplastic resin component) and Br-IPMS [Exxon Corp./EXXPRO as the elastomer component in the tire radial direction center side portion. 89-4], and the ratio is 55:45 (storage elastic modulus 100 MPa)), and the rubber radial layer (60 ° C. tan δ is 0.20) (storage elastic modulus 4.9 MPa).

  The side reinforcing member in the tire 3 of the present invention is formed of a thermoplastic resin (nylon 11 [Atchem Corp./Rilsan BMNO TL] (storage elastic modulus 200 MPa)) at the tire radial direction center side portion, and the tire radial direction outer side portion and inner side portion. Was composed of a thermoplastic elastomer composition (nylon 11 / Br-IPMS = 40: 60 (storage modulus 50 MPa)).

  The side reinforcing member in the conventional tire uses a thermoplastic elastomer composition (nylon 11 [Atchem Corp./Rilsan BMNO TL] as a thermoplastic resin component, and Br-IPMS [Exxon Corp./EXXPRO 89-4] as an elastomer component. The ratio was 55:45 (storage elastic modulus 100 MPa).

  When each of these test tires was subjected to an evaluation test of riding comfort during normal running and durability during run flat running under the measurement conditions shown below, the results shown in Table 1 were obtained.

Riding comfort Each test tire is mounted on a rim with a rim size of 17 × 9-JJ, mounted on a vehicle with a displacement of 3000 cc with an air pressure of 230 kPa, and a sensory evaluation test is conducted by a test driver on the test course. The conventional tire is indicated by an index value of 100. The larger this value, the better the riding comfort during normal driving.

Durability Each test tire is mounted on a rim with a rim size of 17x9-JJ, mounted on the right side of the front wheel of a 3000cc vehicle with air pressure set to 0, and the distance traveled until the vehicle becomes unable to travel on the test course is measured. The results are shown as index values with the conventional tire as 100. The larger this value, the better the durability during run-flat running.

  From Table 1, it can be seen that the tire of the present invention can improve the ride comfort while maintaining the durability at the time of run-flat running at or above the conventional level.

2 Side wall portion 10 Side reinforcing member 10A Tire radial direction outer side portion 10B Tire radial direction inner side portion 10C Tire radial direction central side portion S Strip material

Claims (7)

  A side reinforcing member having a crescent-shaped cross section that enables run-flat running is disposed on the sidewall portion, and the side reinforcing member is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component. The pneumatic tire according to the pneumatic tire, wherein the storage elastic modulus of the side reinforcing member is lower in the tire radial direction outer side and / or the inner side than the tire radial direction central side.   2. The pneumatic tire according to claim 1, wherein the side reinforcing member is made of a thermoplastic elastomer composition, and the elastomer component is increased on the outer side and / or the inner side in the tire radial direction from the center side in the tire radial direction of the side reinforcing member.   The side reinforcing member is configured such that the center side in the tire radial direction is made of a thermoplastic elastomer composition, and the outer side and / or the inner side in the tire radial direction is formed with a rubber layer interposed between layers made of a thermoplastic resin or a thermoplastic elastomer composition. The pneumatic tire according to claim 1.   2. The pneumatic tire according to claim 1, wherein the side reinforcing member is formed of a thermoplastic resin at a tire radial direction center side and a tire radial direction outer side and / or inner side is formed of a thermoplastic elastomer composition.   The pneumatic tire according to any one of claims 1 to 4, wherein the storage elastic modulus of the side reinforcing member is gradually lowered toward the outer side and / or the inner side in the tire radial direction.   The pneumatic tire according to any one of claims 1 to 5, wherein tan δ at 60 ° C of the thermoplastic resin and the thermoplastic elastomer composition is 0.04 to 0.3, respectively.   The pneumatic tire according to any one of claims 1 to 6, wherein the side reinforcing member is configured by winding a strip material in a tire circumferential direction.

Images