JP2010125890A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having increased tire rigidity with no increased mass while imparting an air permeation preventing function to a carcass layer. <P>SOLUTION: The pneumatic tire is mounted with the carcass layer 4 including a plurality of carcass cords C aligned to one another between a pair of bead parts. The pneumatic tire includes a resin-containing coat layer 14a formed of a thermoplastic elastomer composition of a thermoplastic resin or the thermoplastic resin and elastomer blended, and provided on at least the inner face side of the carcass layer 4 in contact with the carcass cords C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a carcass layer is mounted between a pair of bead portions. More specifically, the tire rigidity is increased without causing an increase in mass, and further, an air permeation preventing function is imparted to the carcass layer. The present invention relates to a pneumatic tire.

  A pneumatic tire usually includes a casing structure in which a carcass layer is mounted between a pair of bead portions, and a belt layer is disposed on the outer peripheral side of the carcass layer. In such a pneumatic tire, the carcass layer includes a plurality of aligned carcass cords, and the carcass cords are covered with a coat rubber (see, for example, Patent Document 1).

  By the way, in order to improve traveling performance such as steering stability of a pneumatic tire, it is necessary to increase tire rigidity. In order to increase the tire rigidity, it is effective to increase the number of carcass layers or to add a reinforcing layer to the sidewall portion or the like. However, when the number of carcass layers is increased or a reinforcing layer is added, there is a drawback that the mass of the tire increases.

In order to improve the air permeation prevention function of the pneumatic tire, it is effective to increase the thickness of the inner liner layer. However, increasing the thickness of the inner liner layer also increases the mass of the tire.
JP 2007-30636 A

  An object of the present invention is to provide a pneumatic tire capable of increasing tire rigidity without causing an increase in mass and further providing an air permeation preventing function to a carcass layer.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire including a carcass layer including a plurality of carcass cords arranged between a pair of bead portions, and at least an inner surface side of the carcass layer. And a resin-containing coating layer made of a thermoplastic elastomer composition obtained by blending a thermoplastic resin or a thermoplastic resin and an elastomer so as to be in contact with the carcass cord.

  In the present invention, since the resin-containing coating layer made of a thermoplastic resin or a thermoplastic elastomer composition is provided on at least the inner surface side of the carcass layer so as to be in contact with the carcass cord, the coating layer of the carcass layer is made of the rubber composition. Compared to a conventional tire, the tire rigidity can be increased without increasing the mass. In addition, since the resin-containing coating layer has a low air permeability, by disposing the resin-containing coating layer on at least the inner surface side of the carcass layer, an air permeation preventing function can be imparted to the carcass layer.

  In the present invention, it is preferable to provide a resin coating layer on the inner surface side of the carcass layer, while providing a rubber coating layer on the outer surface side of the carcass layer. Thereby, generation | occurrence | production of a flat spot can be suppressed. In addition, it is possible to prevent the carcass layer from becoming excessively rigid and prevent a so-called splice open failure due to the opening of the splice when the unvulcanized tire is expanded.

  The resin-containing coating layer has anisotropy, and the elastic modulus in the carcass cord extending direction of the resin-containing coating layer is preferably 1.2 to 5.0 times the elastic modulus in the direction perpendicular thereto. By adopting the resin-containing coating layer having such anisotropy, it is possible to reduce the driving density and thickness of the carcass cord, and as a result, it is possible to reduce the manufacturing cost and reduce the weight of the tire. .

  It is preferable to arrange an inner liner layer made of a thermoplastic elastomer composition obtained by blending a thermoplastic resin or a thermoplastic resin and an elastomer on the inner surface side of the resin-containing coating layer. In this case, since the adhesiveness between the resin-containing coating layer and the inner liner layer is good, the conventionally used tie rubber layer can be eliminated and the tire can be reduced in weight. Since the carcass layer has an air permeation preventing function, the resin-containing coating layer may be disposed so as to be exposed on the tire inner surface, and the carcass layer may be used as an inner liner layer. In this case, it is possible to reduce the weight of the tire by eliminating the inner liner layer and the tie rubber layer made of a low gas-permeable rubber such as butyl rubber. The carcass layer is preferably composed of a seamless cylindrical body. Thereby, the uniformity of a tire can be improved.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIG. 2 shows an enlarged main part of the pneumatic tire. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 including a plurality of carcass cords extending in the tire radial direction is mounted between the pair of left and right bead portions 3, 3, and the carcass layer 4 is wound around the bead core 5 from the inside of the tire to the outside. Yes. As the reinforcing cord for the carcass layer 4, an organic fiber cord such as a nylon cord or a polyester cord is generally used. An inner liner layer 6 is disposed along the carcass layer 4 on the tire inner surface. On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 are arranged such that the reinforcing cords are inclined with respect to the tire circumferential direction and the reinforcing cords cross each other between the layers.

  In the pneumatic tire, as shown in FIG. 2, the carcass layer 4 has a structure in which a plurality of aligned carcass cords C are covered with covering layers 14a and 14b. More specifically, a resin-containing coating layer 14 a made of a thermoplastic resin or a thermoplastic elastomer composition is disposed on the inner surface side of the carcass layer 4 so as to be in contact with the carcass cord C, and on the outer surface side of the carcass layer 4 A rubber coating layer 14b made of a rubber composition is disposed in contact with the cord C. As a constituent material of the rubber coating layer 14b, a rubber composition mainly composed of natural rubber or the like conventionally used for the carcass layer can be used.

  As described above, since the resin-containing coating layer 14a made of a thermoplastic resin or a thermoplastic elastomer composition is provided on at least the inner surface side of the carcass layer 4 so as to be in contact with the carcass cord C, the carcass layer 4 does not increase in mass. Thus, the tire rigidity can be increased. In addition, since the resin-containing coating layer 14a has a low air permeability, the carcass layer 4 can be provided with an air permeation prevention function by disposing the resin-containing coating layer 14a on at least the inner surface side of the carcass layer 4.

  In order to increase the rigidity of the tire, the thickness of the resin-containing coating layer 14a is preferably 50% or more of the carcass cord diameter. In order to increase the rigidity of the tire, it is effective to increase the volume ratio of the thermoplastic resin in the resin-containing coating layer 14a. For example, when the volume ratio of the thermoplastic resin is 40% or more, Even if the thickness of the resin-containing coating layer 14a is about 30% of the carcass cord diameter, the effect of increasing the rigidity of the tire can be obtained.

  When the resin-containing coating layer 14a is disposed not only on the inner surface side but also on the outer surface side of the carcass layer 4, that is, when all the coating layers of the carcass layer 4 are made of a thermoplastic resin or a thermoplastic elastomer composition, The effect of increasing the rigidity becomes remarkable. However, in this case, the rigidity of the carcass layer 4 at the time of tire molding is increased, and when the unvulcanized tire is expanded, the splice portion of the carcass layer 4 is likely to open and a splice open failure is likely to occur. It is preferable to join the butted ends of the splice portions of the carcass layer 4 to each other by thermal fusion before expanding the diameter.

  On the other hand, when the resin-containing coating layer 14a is disposed on the inner surface side of the carcass layer 4 and the rubber coating layer 14b is disposed on the outer surface side of the carcass layer 4, a splice open failure hardly occurs when the unvulcanized tire is expanded. Therefore, it is possible to employ a splice structure in which the end portions of the carcass layer 4 are overlapped without performing heat fusion treatment. Further, if necessary, a tape having a thickness of 50 μm to 200 μm made of a thermoplastic resin or a thermoplastic elastomer composition may be used, and the tape may be bonded so as to straddle the butted end portion of the resin-containing coating layer 14a. . When the resin-containing coating layer 14 a is disposed on the inner surface side of the carcass layer 4 and the rubber coating layer 14 b is disposed on the outer surface side of the carcass layer 4, there is an advantage that a flat spot is hardly generated.

  The carcass cord C in the carcass layer 4 may be a conventional one, but in consideration of the elastic modulus of the constituent material of the resin-containing coating layer 14a, the one having a lower elastic modulus than the conventional one is used. Also good. The constituent material of the resin-containing coating layer 14a has a storage elastic modulus at 20 ° C. of 150 MPa or less, and more preferably 5 MPa to 120 MPa. If the elastic modulus of the constituent material of the resin-containing coating layer 14a exceeds 150 MPa, the material is too rigid and it becomes difficult to manufacture the tire. The storage elastic modulus is measured using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho under the conditions of a temperature of 20 ° C., a static strain of 10%, a dynamic strain of ± 2%, and a frequency of 20 Hz.

  The resin-containing coating layer 14a has anisotropy, and the elastic modulus in the carcass cord extending direction of the resin-containing coating layer 14a is 1.2 to 5.0 times the elastic modulus in the direction perpendicular thereto, more preferably 1 .5 times to 2.5 times is good. By adopting the resin-containing coating layer 14a having such anisotropy, it is possible to reduce the driving density and thickness of the carcass cord C. As a result, it is possible to reduce the manufacturing cost and the weight of the tire. become. In order to give anisotropy to the resin-containing coating layer 14a, short fibers may be blended in the constituent material, and the short fibers may be oriented in the carcass cord extending direction. Alternatively, the constituent material of the resin-containing coating layer 14a may be stretched.

  In FIG. 2, the inner liner layer 6 is disposed on the inner surface side of the resin-containing coating layer 14a so as to be exposed on the inner surface of the tire, and the tire constituent members such as the sidewall rubber layer 8 are disposed on the outer surface side of the rubber coating layer 14b. However, the inner liner layer 6 is made of a thermoplastic resin or a thermoplastic elastomer composition. In this case, since both the resin-containing coating layer 14a and the inner liner layer 6 contain a thermoplastic resin, they can be bonded without an adhesive layer or through a thin adhesive layer having a thickness of 30 μm or less. . Therefore, the conventionally used tie rubber layer can be eliminated and the tire can be reduced in weight.

  Since the carcass layer 4 has an air permeation prevention function, as shown in FIG. 3, the resin-containing coating layer 14a may be disposed so as to be exposed on the tire inner surface, and the carcass layer 4 may be used as an inner liner layer. In this case, it is possible to reduce the weight of the tire by eliminating the inner liner layer and the tie rubber layer made of a low gas-permeable rubber such as butyl rubber. Of course, as shown in FIG. 4, an inner liner layer 16 or a tie rubber layer 17 made of a low gas-permeable rubber such as butyl rubber may be provided on the inner surface side of the resin-containing coating layer 14a.

  The carcass layer 4 is preferably composed of a seamless cylindrical body. For example, as the carcass layer 4, a cylindrical resin-containing coating layer 14 a made of a thermoplastic resin or a thermoplastic elastomer composition is formed by a known cylindrical inflation molding method, and the carcass layer 4 is formed with respect to the cylindrical resin-containing coating layer 14 a. What crimped | bonded the composite_body | complex of the code | cord | chord C and the rubber coating layer 14b can be used. Alternatively, a composite of the carcass cord C, the resin-containing coating layer 14a, and the rubber coating layer 14b is formed into a sheet shape, the sheet-shaped composite is rounded into a cylindrical shape, and the ends of the splice portion do not overlap each other. After butting, the butted ends can be joined to each other by thermal fusion and have a substantially seamless structure. Thus, by using the carcass layer 4 made of a seamless cylindrical body, the uniformity of the tire can be improved.

  Hereinafter, the constituent materials of the resin-containing coating layer and inner liner layer used in the present invention will be described. The resin-containing coating layer and the inner liner layer can be composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin and an elastomer.

  Examples of the thermoplastic resin used in the present invention include polyamide resins [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 copolymers Methoxymethylated product of nylon 612, methoxymethylated product of nylon 612, polyester resin [for example, poly Tylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimide diacid / Aromatic polyesters such as polybutylene terephthalate copolymer], polynitrile resins [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) acrylonitrile / styrene copolymer, (Meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resin [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl resin [for example, acetic acid Nyl, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDVC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer , Vinylidene chloride / acrylonitrile copolymer (ETFE)], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate], fluorine resin [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoro Ethylene (PCTFE), tetrafluoroethylene / ethylene copolymer], an imide resin [for example, aromatic polyimide (PI)] and the like can be preferably used.

  Examples of the elastomer used in the present invention include diene rubber and hydrogenated products thereof [for example, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene rubber ( BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubber [for example, 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, isobutylene paramethylstyrene copolymer Combined bromide (Br-IPMS), chloroprene rubber (CR Hydrin 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 rubber) Phosphazene rubbers], thermoplastic elastomers (for example, styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, polyamido elastomers) can be preferably used. .

  When the above-mentioned specific thermoplastic resin and elastomer are different in compatibility, they can be made compatible by using an appropriate compatibilizing agent as the third component. By mixing the compatibilizer with the blend system, the interfacial tension between the thermoplastic resin and the elastomer decreases, and as a result, the rubber particle size forming the dispersion layer becomes finer, so the characteristics of both components are more It will be expressed effectively. Such a compatibilizing agent generally includes a copolymer having a structure of both or one of a thermoplastic resin and an elastomer, or an epoxy group, a carbonyl group, a halogen group, and an amino group that can react with the thermoplastic resin or elastomer. In addition, a copolymer having a oxazoline group, a hydroxyl group and the like can be taken. These may be selected according to the type of thermoplastic resin and elastomer to be mixed, but those commonly 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 modified maleic acid, styrene / maleic acid copolymer, reactive phenoxin and the like can be mentioned. The amount of the compatibilizing agent is not particularly limited, but 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).

  In the thermoplastic elastomer composition, the composition ratio between the specific thermoplastic resin and the elastomer is not particularly limited, and is appropriately determined so as to have a structure in which the elastomer is dispersed as a discontinuous phase in the thermoplastic resin matrix. The preferred range is 90/10 to 30/70 by weight.

  In the present invention, the thermoplastic resin and the thermoplastic elastomer composition constituting the resin-containing coating layer and the inner liner layer are mixed with other polymers such as the above-described compatibilizer within a range not damaging the necessary characteristics as a tire member. can do. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer, to improve the molding processability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material that can be used include polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, SBS, and polycarbonate (PC). In addition, fillers (calcium carbonate, titanium oxide, alumina, etc.) generally incorporated into polymer blends, reinforcing agents such as carbon black and white carbon, softeners, plasticizers, processing aids, pigments, dyes, and aging An inhibitor or the like can be arbitrarily blended as long as necessary characteristics as a tire member are not impaired.

  The elastomer can also be dynamically vulcanized when mixed with the thermoplastic resin. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time), and the like in the case of dynamic vulcanization may be appropriately determined according to the composition of the elastomer 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. 4 phr [In the present specification, “phr” refers to parts by weight per 100 parts by weight of the elastomer component. same as below. ] 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) and the like 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 to 20 phr), p-quinonedioxime, p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone, poly-p- Examples include dinitrosobenzene (about 2 to 10 phr) and methylene dianiline (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 includes a thermoplastic resin in which a thermoplastic resin and an elastomer (unvulcanized in the case of rubber) are melt-kneaded in advance using a twin-screw kneading extruder or the like to form a continuous phase (matrix). By dispersing the elastomer as a dispersed phase (domain) in it. When the elastomer is vulcanized, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer. Further, various compounding agents (excluding the vulcanizing agent) for the thermoplastic resin or elastomer may be added during the kneading, but it is preferable to mix them in advance before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer is not particularly limited, and a screw extruder, a kneader, a Banbury mixer, a biaxial kneading extruder, or the like can be used. Among these, it is preferable to use a twin-screw kneading extruder for kneading the thermoplastic resin and the elastomer and for dynamic vulcanization of the elastomer. 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. The shear rate during kneading is preferably 1000 to 7500 sec ⁻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. What is necessary is just to make the polymer composition manufactured by the said method into a desired shape with the shaping | molding methods of normal thermoplastic resin, such as injection molding and extrusion molding.

  The thermoplastic elastomer composition thus obtained has a structure in which an elastomer is dispersed as a discontinuous phase in a matrix of a thermoplastic resin. By taking such a structure, the resin-containing coating layer and inner liner layer can be provided with sufficient flexibility and sufficient rigidity by the effect of the resin layer as a continuous phase, and can be molded regardless of the amount of elastomer. In this case, molding processability equivalent to that of the thermoplastic resin can be obtained.

  The thermoplastic resin or thermoplastic elastomer composition can be formed into a sheet or film and used alone, but an adhesive layer may be laminated to improve the adhesion to the adjacent rubber. Specific examples of the adhesive polymer constituting the adhesive layer include ultrahigh molecular weight polyethylene (UHMWPE), ethylene ethyl acrylate copolymer (EEA), ethylene methyl acrylate resin (EMA) having a molecular weight of 1 million or more, preferably 3 million or more. ), Acrylate copolymers such as ethylene acrylic acid copolymer (EAA) and their maleic anhydride adducts, polypropylene (PP) and its maleic acid modification, ethylene propylene copolymer and its maleic acid modification, Polybutadiene resin and its modified maleic anhydride, styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), fluorine thermoplastic resin, polyester thermoplastic resin, etc. Can be mentioned. These can be extruded into a sheet shape or a film shape by a conventional method, for example, by a resin extruder. The thickness of the adhesive layer is not particularly limited, but it is preferable that the thickness is small in order to reduce the weight of the tire, and 5 μm to 150 μm is preferable.

  In a pneumatic tire having a tire size of 205 / 55R16, in which a carcass layer including a plurality of carcass cords arranged between a pair of bead portions is mounted, and a belt layer is disposed on the outer peripheral side of the carcass layer, Conventional tires and tires of Examples 1 to 3 having different structures of the carcass layer and the inner liner layer were manufactured.

  The tire of the conventional example uses a rubber composition mainly composed of natural rubber as a constituent material of the covering layer of the carcass layer, and has a thickness of 0.5 mm made of a rubber composition mainly composed of butyl rubber along the inner surface of the carcass layer. This inner liner layer is disposed together with a tie rubber layer. The tire of Example 1 uses a thermoplastic elastomer composition in which a thermoplastic resin (nylon 6,66) and an elastomer (brominated butyl rubber) are blended as a constituent material of the coating layer on the inner surface side of the carcass layer. A rubber composition mainly composed of natural rubber is used as a constituent material of the outer surface side coating layer, and an inner liner layer having a thickness of 0.05 mm made of the same thermoplastic elastomer composition is disposed along the inner surface of the carcass layer. It is a thing. The tire of Example 2 has the same configuration as Example 1 except that the inner liner layer is removed. The tire of Example 3 has the same configuration as Example 1 except that a 0.5 mm thick inner liner layer made of a rubber composition mainly composed of butyl rubber is disposed along with the tie rubber layer along the inner surface of the carcass layer. Is.

  About the tire of the above-described conventional example and Examples 1 to 3, mass, longitudinal rigidity, and lateral rigidity were measured, and air leakage resistance was evaluated by the following evaluation method. The results are shown in Table 1.

Air leakage resistance:
Each test tire was assembled on a standard rim, and was left for 3 months at an initial internal pressure of 220 kPa and a room temperature of 21 ° under no load conditions, and the internal pressure was measured every day. Then, as the initial internal pressure Po, the measured internal pressure Pt, and the elapsed days t, the function Pt / Po = exp (−αt) was regressed to obtain the α value. Using the obtained α value, t = 30 was substituted into the following equation to obtain a β value corresponding to the pressure drop rate per month (% / month).

β = [1-exp (−αt)] × 100
The evaluation results are shown as a difference (%) with respect to the standard based on the pressure drop rate of the conventional example. A negative value means that the pressure drop rate is lower than that of the conventional example and the air leakage resistance is excellent.

  As is apparent from Table 1, the tires of Examples 1 to 3 were able to increase the tire rigidity without causing an increase in mass compared to the conventional example. In the tires of Examples 1 to 3, it was clear that the carcass layer had an air permeation prevention function.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is sectional drawing which expands and shows the principal part of the pneumatic tire which consists of embodiment of this invention. It is sectional drawing which shows the modification of the principal part of the pneumatic tire of this invention. It is sectional drawing which shows the other modification of the principal part of the pneumatic tire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Inner liner layer 7 Belt layer 8 Side wall rubber layer 14a Resin-containing coating layer 14b Rubber coating layer C Carcass cord

Claims (6)

  In a pneumatic tire in which a carcass layer including a plurality of carcass cords arranged between a pair of bead portions is mounted, a thermoplastic resin or a thermoplastic resin so as to be in contact with the carcass cord at least on the inner surface side of the carcass layer A pneumatic tire comprising a resin-containing coating layer made of a thermoplastic elastomer composition obtained by blending an elastomer and an elastomer.   The pneumatic tire according to claim 1, wherein the resin-containing coating layer is provided on the inner surface side of the carcass layer, and the rubber coating layer is provided on the outer surface side of the carcass layer.   The resin-containing coating layer has anisotropy, and the elastic modulus in the carcass cord extending direction of the resin-containing coating layer is 1.2 to 5.0 times the elastic modulus in the direction perpendicular thereto. The pneumatic tire according to claim 1 or claim 2.   The inner liner layer which consists of a thermoplastic elastomer composition which blended the thermoplastic resin or a thermoplastic resin, and an elastomer on the inner surface side of the said resin containing coating layer has been arrange | positioned, The any one of Claims 1-3 characterized by the above-mentioned. Pneumatic tires.   The pneumatic tire according to claim 1, wherein the resin-containing coating layer is disposed so as to be exposed on an inner surface of the tire.   The pneumatic tire according to claim 1, wherein the carcass layer provided with the resin-containing coating layer is formed of a seamless cylindrical body.

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