JPH11180110A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure superior driving performance while improving resistance to edge separation of the belt layers and controlling the increase in weight as much as possible. SOLUTION: Two belt layers, one internal and one external, 7A, 7B, respectively, that are located at the periphery of a carcass 4 of a tread 1 are in an extending spiral structure with a reinforcement cord folded back from one direction to the other at the edge of the belt layers 7A, 7B. Located between the belt layers 7A, 7B is a belt reinforcement layer 8. The belt reinforcement layer 8 is composed of thermoplastic olefin elastomer composition that is a blend of a thermoplastic resin or thermoplastic resin components and elastomer components where Young's modulus is 10-1500 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of improving exercise performance while suppressing tire weight.

[0002]

2. Description of the Related Art Conventionally, in order to improve the edge separation of a belt layer, two inner and outer belt layers are formed into a spiral winding structure in which a reinforcing cord is folded back from one side to the other belt layer at the edge thereof. There are pneumatic tire proposals. In this way, by using the spirally wound structure while sharing the reinforcing cords of the inner and outer belt layers, the cut end of the reinforcing cord that causes edge separation is not located at the edge of the belt layer. Thus, the edge separation resistance of the belt layer is enhanced.

[0003] However, for example, when organic fibers are used for the reinforcing cord to reduce the weight, the central portion of the tread portion tends to swell, and the cornering force is reduced due to insufficient rigidity of the belt layer. There was a problem that it was difficult to obtain performance. Further, in a conventional heavy-duty pneumatic tire used for a light truck or a bus, for example, when the belt layer has a three-layer structure, there is a problem that it cannot be dealt with.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire capable of always improving the edge separation resistance of a belt layer and ensuring good exercise performance while minimizing an increase in weight. Is to provide.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an inner and outer belt layer embedded on the outer peripheral side of a carcass layer of a tread portion. And a belt reinforcing layer is disposed between the inner and outer belt layers, and the belt reinforcing layer has a Young's modulus of 10 to 1500.
It is characterized by comprising a thermoplastic resin of MPa or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component.

[0006] As described above, the inner and outer belt layers are formed into a spiral wound structure in which the reinforcing cords are folded back from one side to the other side so that the cut ends of the reinforcing cords do not protrude to the edge of the belt layer. Therefore, the occurrence of edge separation of the belt layer due to the cut end of the reinforcing cord can be suppressed, and the weight increases because the belt reinforcing layer made of a lightweight thermoplastic resin or a thermoplastic elastomer composition is disposed. Can be suppressed as much as possible.

In addition, since the Young's modulus of the thermoplastic resin or the thermoplastic elastomer composition constituting the belt reinforcing layer interposed between the belt layers is set as described above to increase the rigidity, the reinforcing cord of the belt layer can be used. Even if organic fibers are used, the central part of the tread is unlikely to swell,
Insufficient rigidity of the belt layer can be compensated. Therefore, it is possible to improve the cornering force and improve the exercise performance.

Further, by adjusting the thickness of the belt reinforcing layer, it is possible to improve the edge separation resistance of the belt layer and to suppress the increase in weight as much as possible while maintaining the belt layer having the conventional three-layer structure for heavy loads. Good exercise performance close to a pneumatic tire can also be secured. In the case where the inner and outer belt layers have a spiral wound structure in which the reinforcing cords are folded back from one side to the other side as described above, a plurality of reinforcing cords are arranged in a matrix during green tire molding. The unvulcanized deep strip material condensed by the above is continuously formed into a spiral shape with a width corresponding to the belt layer width, but in the present invention, the belt reinforcing layer itself becomes a core, so that the belt It can be formed while winding the strip material around the reinforcing layer. As a result, the belt layer can be easily formed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an example 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 sidewalls 3 are extended outwardly in the tire radial direction in connection with the left and right bead portions 2, and a tread portion 1 extending in the tire circumferential direction is provided between the left and right sidewall portions 3.

One carcass layer 4 is provided inside the tire. Beat cores 5 are respectively arranged on the left and right bead portions 2, and bead fillers 6 are provided on the outer periphery of the beat cores 5. Both ends 4 a of the carcass layer 4 are folded from the inside of the tire to the outside around the beat core 5 so as to surround the bead filler 6. A plurality (two layers in the figure) of belt layers 7 in which reinforcing cords are arranged are embedded on the outer peripheral side of the carcass layer of the tread portion 1.

According to the present invention, in the pneumatic tire having the above-described structure, the inner and outer belt layers 7A and 7B are formed in an endless integrated structure in which both ends of the left and right belt layers 7A and 7B are connected to each other. I have. The reinforcing cords f of the belt layers 7A and 7B are arranged so as to be inclined with respect to the tire circumferential direction T, and are arranged so as to cross each other. The reinforcing cord f has a spiral wound structure that is folded back from one side to the other (and one from the other side) at the edge portions of the belt layers 7A and 7B, and the cut end of the reinforcing cord f is a belt. The layers 7A and 7B are not located at the edges.

Between the inner and outer belt layers 7A and 7B, a belt reinforcing layer 8 extending between the left and right belt layer edges is provided.
Are arranged along the tire circumferential direction. The belt reinforcing layer 8 is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, and has a Young's modulus of 10 to 1500 MPa.
It has become.

Since the cut end of the reinforcing cord f is not exposed to the edges of the belt layers 7A and 7B as described above, the belt layer has an edge resistant edge generated due to the cut end of the reinforcing cord. The separation property can be improved, and a lightweight thermoplastic resin or thermoplastic elastomer composition is used as the belt reinforcing layer 8 disposed between the belt layers 7A and 7B without using a reinforcing layer in which a reinforcing cord is embedded. Since a product is used, an increase in weight can be suppressed as much as possible.

Since the rigidity of the thermoplastic resin or the thermoplastic elastomer composition constituting the belt reinforcing layer 8 interposed between the belt layers 7A and 7B is increased within the above-mentioned range, the rigidity of the belt layer 7A is increased. , 7B reinforcement cord f
Even when organic fibers are used, the central portion of the tread portion is unlikely to swell, and the insufficient rigidity of the belt layer can be sufficiently compensated for, so that a decrease in cornering force can be improved and good exercise performance can be secured. Becomes possible.

Further, by adjusting the thickness of the belt reinforcing layer 8, a belt layer having a conventional three-layer structure is arranged while improving the edge separation resistance of the belt layer and minimizing an increase in weight. Good exercise performance close to that of a heavy-duty pneumatic tire can also be secured. Further, the belt layers 7A and 7B in which the cut ends of the above-described reinforcing cords f are not positioned at the edge portions of the belt layer are formed by unifying a plurality of reinforcing cords f and gathering them by a matrix during green tire molding. The vulcanized, tape-shaped strip material is continuously spirally formed with a width corresponding to the belt layer width. In the present invention, however, the belt reinforcing layer 8 is disposed so as to be a core as described above. In addition, the strip material can be formed while being wound around the belt reinforcing layer 8, so that the forming of the belt layer can be facilitated and the productivity can be increased.

When the Young's modulus is less than 10 MPa,
If the rigidity of the belt reinforcing layer 8 becomes too low, it is difficult to secure good exercise performance. Conversely, if it exceeds 1500 MPa, the rigidity of the belt reinforcing layer 8 becomes too high, so that the belt becomes fragile and tire failure occurs. Cause. Although the belt reinforcing layer 8 is shown as an example in which one layer is disposed in the figure, a plurality of layers may be provided. In the present invention, at least one layer may be disposed. The total thickness is 0.5
~ 6 mm. If the thickness is less than 0.5 mm, the rigidity of the belt reinforcing layer 8 becomes too low, and good exercise performance cannot be ensured. Conversely, if it exceeds 6 mm, the weight increases greatly and the weight is reduced. It is difficult to contribute to the development. The thickness of one layer of the belt reinforcing layer 8 is set to 0.
It is good to set it to 5 to 3.0 mm.

The annular belt reinforcing layer 8 disposed between the belt layers 7A and 7B may be formed in an annular shape in which a sheet-like thin film is seamlessly formed by extrusion molding.
A tape-shaped thin film made of a thin film may be continuously wound spirally without any gap to form an annular shape, and furthermore, the front and rear ends of the film formed into a wide sheet may be joined.

The reinforcing cords f of the belt layers 7A and 7B can be composed of organic fiber cords. As the organic fiber cord, conventionally known ones can be used, for example, polyarylate fiber, polyparaphenylene benzobisoxazole fiber, polyvinyl alcohol fiber, rayon fiber, polyethylene terephthalate fiber,
A twisted yarn obtained by twisting one or more kinds of fibers selected from polyethylene 2,6-naphthalate fiber, nylon fiber, aromatic polyamide fiber and the like can be used. Preferably, an aromatic polyamide fiber cord having substantially the same strength as a steel cord and having a high flexibility is preferred.

Further, a steel cord may be used as the reinforcing cord f. In this case, it is preferable that the thickness of the belt reinforcing layer 8 serving as the core be 1.0 mm or more in order to facilitate the winding formability of the strip material constituting the belt layer. Further, in a heavy-duty pneumatic tire having a three-layered belt layer using a conventional steel cord as a reinforcing cord, belt layers 7A and 7B having the above-described configuration are disposed instead of the three-layered belt layer. When the belt reinforcing layer 8 is interposed therebetween, it is preferable that the thickness of the belt reinforcing layer 8 be 0.8 mm or more, thereby improving the edge separation resistance of the belt layer and reducing the weight. In this way, it is possible to ensure good exercise performance in the heavy-duty pneumatic tire.

The reinforcing cord f can be oriented at an inclination angle of 15 to 75 ° with respect to the tire circumferential direction. For example, as shown in FIG. 3, the inner and outer belt layers 7A and 7B with the belt reinforcing layer 8 interposed therebetween are arranged in a matrix (rubber) by arranging a plurality of reinforcing cords around a belt reinforcing layer 8 previously formed by heating. The unvulcanized belt layer 7 with the belt reinforcing layer 8 shown in FIG. 4 interposed therebetween is formed by continuously turning the unvulcanized deep strip material 9 converged with plastic and wrapping it without any gap. 'Can be formed. By arranging this on an unvulcanized carcass layer wound on a forming drum, it is possible to assemble a green tire.

In this method, the width of the strip material 9, the angle with respect to the tire circumferential direction, and the like are uniquely determined by the outer diameter of the belt layer and the width of the belt layer. The relational expression is shown below (see FIG. 3). Assuming that the radius of the belt layer is r, its outer peripheral length L
Is L = 2πr. When the outer peripheral length L is divided into N, the span length m per division is as follows.

M = 2πr / N When the uncured strip material 9 is wound around the tire one round, it returns to the same position. Therefore, as shown in FIG. 3, the belt is reinforced by shifting the strip material circumferential width d. Layer 8
Wrap around. Therefore, L = (N-1) m + (m ± d) ∴ (L ± d) / N = m ··· Next, the inclination angle θ with respect to the tire circumferential direction of the belt layer width W _B and the strip member 9, span Looking at the relationship between the length _{m, tanθ = W B / m} / 2 from m = 2W _B / tanθ ··· also, since the span length m is an integer multiple of the strip material circumferential width d, m = nd · · When the equation is substituted into the equation, (L ± d) / N = m = nd∴L = nNd− (± d) where n and N are integers. Strip material circumference d is
d = W _T / sin θ (W _T is the width of the strip material 9).

The belt layers 7A and 7B with the belt reinforcing layer 8 interposed therebetween can be manufactured as described above, but it goes without saying that other methods may be used. . In the present invention, the thermoplastic resin is not particularly limited as long as it can make the Young's modulus 10 to 1500 MPa. For example, a polyolefin resin [for example, low density polyethylene (LDPE), linear Low density polyethylene (LLDP
E), high density polyethylene (HDPE), homopolypropylene, block polypropylene, random polypropylene, and modified products thereof, for example, maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene,
Epoxy-modified polypropylene], styrene-based resin [for example, general-purpose polystyrene (PS), impact-resistant polystyrene (HIPS), acrylonitrile / styrene copolymer (AS), acrylonitrile / retine / butadiene copolymer (ABS), methyl methacrylate / Styrene copolymer (MS)], polyamide resin [eg, nylon 6 (N6), nylon 66 (N66), nylon 46]
(N46), nylon 11 (N11), nylon 12
(N12), nylon 610 (N610), nylon 6
12 (N612), nylon 6/66 copolymer (N6 /
66), nylon 6/66/610 copolymer (N6 / 6
6/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / P
P copolymer, nylon 66 / PPS copolymer] and N-alkoxyalkylated products thereof, for example, methoxymethylated 6-nylon, methoxymethylated 6-610-nylon, methoxymethylated 612-nylon, Polyester resin [for example, polybutylene terephthalate (PBT), polyethylene terephthalate (P
ET), polyethylene isophthalate (PEI), PE
T / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester,
Aromatic polyesters such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymers), polyether resins [eg, polyacetal (POM),
Polyphenylene oxide (PPO), polyethersulfone (PES), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide (PEI), polynitrile resin [for example, polyacrylonitrile (PAN), polymethacryloyl Nitrile], polymethacrylate-based resin [eg, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl-based resin [eg, vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), Polyvinylidene chloride (PDV
C), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate] , Fluororesin [for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PV
F), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETF
E)], imide-based resin [for example, aromatic polyimide (P
I)] and the like can be preferably used.

Further, a polymer alloy obtained by mixing two or more kinds of the above-mentioned polymers can be used in the same manner. For example,
Alloyed product of polyphenylene oxide / polystyrene, alloyed product of ABS / polycarbonate, alloyed product of nylon 6 / polyphenylene oxide, PET /
An alloy of PBT may be mentioned. The thermoplastic elastomer composition can be constituted by mixing an elastomer component with the above-described thermoplastic resin component, and if this is also blended so that the Young's modulus becomes 10 to 1500 MPa, the material of the material can be used. The type and the mixing ratio are not particularly limited.

Examples of the elastomer include diene rubbers and hydrogenated products thereof (eg, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis B).
R), NBR, hydrogenated NBR, hydrogenated SBR], olefin-based rubber [for example, ethylene propylene rubber (EPD)
M, EPM), maleic acid-modified ethylene propylene rubber (M-EPM), IIR, copolymer of isobutylene and aromatic vinyl or diene monomer, acrylic rubber (AC
M), ionomers], halogen-containing rubbers (for example, Br
-IIR, CI-IIR, bromide of isobutylene paramethylstyrene copolymer (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 [for example, methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber], sulfur-containing rubber [for example, polysulfide rubber], fluorine rubber [for example, Vinylidene fluoride rubber, fluorine-containing vinyl ether rubber,
Tetrafluoroethylene-propylene-based rubber, fluorine-containing silicon-based rubber, fluorine-containing phosphazene-based rubber], thermoplastic elastomer [for example, styrene-based elastomer,
Olefin elastomer, ester elastomer,
Urethane-based elastomer, polyamide-based elastomer)
Etc. can be preferably used.

When the compatibility between the specific thermoplastic resin component and the elastomer component is different, the two components can be made compatible with each other 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 decreases, and as a result, the rubber particle diameter forming the dispersion layer becomes fine, so that the properties of both components are reduced. It will be more effectively expressed. As such a compatibilizer, generally, a copolymer having a structure of both or one of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen group, which can react with the thermoplastic resin or the elastomer component, The copolymer may have a structure having an amino group, an oxazoline group, a hydroxyl group, or the like. These may be selected according to the type of the thermoplastic resin and the elastomer component to be mixed, and those usually used include styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid-modified product, EPDM, EPM And EPDM / styrene or EPDM / acrylonitrile graft copolymers and their maleic acid-modified products, styrene / maleic acid copolymers, and reactive phenoxines.
The amount of the compatibilizer is not particularly limited, but is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer component).

When the thermoplastic resin and the elastomer are blended, the composition ratio of the specific thermoplastic resin component (A) to the elastomer component (B) is not particularly limited, and includes a Young's modulus and a film constituting the belt reinforcing layer. May be appropriately determined depending on the thickness of the resin, but a preferable range is 90/10 to 3 by weight.
0/70. In the polymer composition according to the present invention, in addition to the essential polymer component, other polymers such as the above-described compatibilizer polymer may be mixed as long as the necessary properties of the polymer composition for a tire of the present invention are not impaired. it can. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the film forming processability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the materials used include polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, SBS, and polycarbonate (PC). The polymer composition according to the present invention further includes a filler (calcium carbonate, titanium oxide, alumina, etc.), a reinforcing agent such as carbon black and white carbon, a softener, a plasticizer, which are generally added to the polymer compound. Processing aids, pigments, dyes, antioxidants, and the like can be arbitrarily compounded as long as the requirements for the Young's modulus are not impaired.

The elastomer component can be dynamically vulcanized when mixed with a thermoplastic resin. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time) and the like for dynamically vulcanizing may be appropriately determined according to the composition of the elastomer component to be added, and are not particularly limited. . As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specifically, examples of the ionic vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, and alkylphenol disulfide. About 4 phr [parts by weight per 100 parts by weight of the rubber component (polymer)] can be used.

The organic peroxide-based vulcanizing agents include:
Benzoyl peroxide, t-butyl hydroperoxide, 2,4-bichlorobenzoyl peroxide,
Examples thereof include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethylhexane-2,5-di (peroxylbenzoate).
About 1 to 20 phr can be used.

Further, as a phenol resin-based vulcanizing agent, bromide of alkylphenol resin, tin chloride,
A mixed crosslinking system containing a halogen donor such as chloroprene and an alkylphenol resin can be exemplified.
About 20 phr can be used. In addition, zinc white (about 5 phr), magnesium oxide (about 4 phr)
Lisage (about 10 to 20 phr), p-quinone dioxime, p-dibenzoylquinone dioxime, tetrachloro-p-benzoquinone, poly-p-dinitrosobenzene (about 2 to 10 phr), methylene dianiline (0. 2
About 10 to 10 phr).

[0031] If necessary, a vulcanization accelerator may be added. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate, and thiourea, for example, About 2 phr can be used. Specifically, hexamethylenetetramine or the like is used as the aldehyde / ammonia vulcanization accelerator, diphenylguanidine is used as the guanidine vulcanization accelerator, and dibenzothiazyl disulfide is used as the thiazole vulcanization accelerator. DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt, etc., as sulfenamide-based vulcanization accelerators, cyclohexylbenzothiazylsulfenamide (CBS), N-oxydiethylenebenzothiazyl-2- Examples of thiuram-based vulcanization accelerators such as sulfenamide, Nt-butyl-2-benzothiazolesulfenamide, 2- (thymopolynyldithio) benzothiazole and the like include tetramethylthiuram disulfide (TMTD), tetraethyl Thiuram disulfide, tetrame Le monosulfide (TMTM), dipentamethylenethiuram tetrasulfide and the like, as the dithio acid salt-based vulcanization accelerator,
Zn-dimethyldithiocarbamate, Zn-diethyldithiocarbamate, Zn-di-n-butyldithiocarbamate, Zn-ethylphenyldithiocarbamate, T
e-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate,
Examples of thiourea-based vulcanization accelerators such as pipecoline pipecolyl dithiocarbamate include ethylene thiourea and diethyl thiourea.

As the vulcanization accelerating auxiliary, a general rubber auxiliary can be used in combination, for example, zinc white (about 5 phr), stearic acid, oleic acid and Zn salts thereof (2 to 2 phr). About 4 phr) can be used. The method for producing a thermoplastic elastomer composition is as follows: a thermoplastic resin component and an elastomer component (an unvulcanized product in the case of rubber) are used in advance.
By melt-kneading with a shaft kneading extruder or the like, and dispersing an elastomer component in a dispersed phase (domain) in a thermoplastic resin forming a continuous phase (matrix phase). When vulcanizing the elastomer component, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer component. The various additives (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading, but it is preferable to mix them before kneading. The kneader used for kneading the thermoplastic resin and the elastomer component is not particularly limited, and a screw extruder, a kneader, a Banbury mixer, a twin-screw kneader or the like can be used. Above all, 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 kinds of kneaders may be used and the kneading may be performed sequentially. As the conditions for the melt-kneading, the temperature may be at least the temperature at which the thermoplastic resin melts. The shear rate during kneading is preferably from 1,000 to 7,500 Sec ^-1 . The total kneading time is preferably 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after the addition is preferably 15 seconds to 5 minutes. The polymer composition produced by the above method is then formed into a sheet-like film by extrusion or calendering. The method of forming a film may be a method of forming a normal thermoplastic resin or thermoplastic elastomer into a film.

The thin film thus obtained has a structure in which the elastomer component (B) is dispersed as a dispersed phase (domain) in a matrix of the thermoplastic resin (A). By taking such a dispersed structure, thermoplastic processing becomes possible, and sufficient rigidity can be imparted to the film as the belt reinforcing layer by the effect of the resin layer as the continuous phase and the sufficient flexibility. Also, regardless of the amount of the elastomer component, at the time of molding, it is possible to obtain molding processability equivalent to that of a thermoplastic resin.
That is, a film can be formed by extrusion molding or calendar molding.

Adhesion between these films and the rubber layer opposite to each other is performed by applying an adhesive obtained by dissolving a general rubber-based, phenolic resin-based, acrylic copolymer-based, or isocyanate-based polymer and a crosslinking agent to a solvent, Bonding by heat and pressure at the time of vulcanization molding, or bonding resin such as styrene butadiene styrene copolymer (SBS), ethylene ethyl acrylate (EEA), styrene ethylene butylene block copolymer (SEBS) to thermoplastic There is a method in which a multilayer film is prepared by co-extrusion or lamination with a film, and is adhered to a rubber layer during vulcanization. Examples of the solvent-based adhesive include a phenol resin-based resin (Chemlock 220, Road Co., Ltd.), a chlorinated rubber-based resin (Chemrock 205, Chemlock 234B), and an isocyanate-based resin (Chemrock 402).

The present invention is particularly applicable to the two inner and outer belt layers 7.
Pneumatic tires for passenger cars in which an organic fiber cord is used for the reinforcement cords f of A and 7B and the belt reinforcement layer 8 is disposed between the belt layers 7A and 7B, and a steel cord is used for the reinforcement cord f of the belt layers 7A and 7B. And the belt layer 7
It can be suitably used for a heavy-duty pneumatic tire having a belt reinforcing layer 8 disposed between A and 7B.

[0036]

Example 1 A tire 1 of the present invention in which the tire size is common to 195 / 70R14 and the above-described belt reinforcing layer is disposed between the inner and outer belt layers having the structure shown in FIG. Comparative tire 1 in which a nylon cord reinforcing layer was disposed, and conventional tire 1 in which a belt reinforcing layer was not provided in tire 1 of the present invention were manufactured.

In each of the test tires, an aramid fiber cord (1500 d / 250 cords / 5 cm) was used as a reinforcing cord for the belt layer, and its inclination angle was 22 °. Inventive tire 1
Nylon 11 (trade name: Rilsan BESN OTL / Atochem) and Br-
A material obtained by blending IPMS (trade name: EXXPRO89-4 / Exxon Chemical Co., Ltd.) at a ratio of 50/50 was used. This material is mixed with a twin-screw kneader to disperse the elastomer in the resin component, then zinc white, stearic acid,
Zinc stearate was added as a 0.4 v, 2 phr, and 1 phr dynamic vulcanizing system, respectively, and mixed by a twin-screw kneader. This was further subjected to extrusion molding of a normal thermoplastic resin to produce a belt reinforcing layer. Its Young's modulus is 50 MPa and its wall thickness is 1.0 mm.

As for the adhesive between the belt reinforcing layer and the rubber part material, Chemlock 234B (Road Far East) was previously applied to the belt reinforcing layer. Each of the test tires was evaluated for exercise performance and tire weight under the following measurement conditions, and the results shown in Table 1 were obtained. Athletic performance Each test tire was mounted on a rim with a rim size of 13 × 5.0 J, the air pressure was set to 200 kPa, and the tire was mounted on a vehicle with a displacement of 2500 cc. The result was evaluated by an index value with the conventional tire 1 being 100.
The higher the value, the better the exercise performance. Tire weight The weight of each test tire was measured, and the results were compared with those of the conventional tire 1.
Was evaluated with an index value of 100. The larger the value,
Heavy weight.

[0039]

[Table 1]

From Table 1, it can be seen that the tire 1 of the present invention has substantially the same level of kinetic performance as the comparative tire 1, but is lighter in weight than the comparative tire 1 and can ensure good kinetic performance. I understand.

It should be noted that the tire 1 of the present invention is structurally evident, without conducting an evaluation test, in that the edge separation resistance of the belt layer can be made equivalent to that of the conventional tire. Example 2 Tire 2 of the present invention in which the tire size was made common to 195 / 70R14 and the above-mentioned belt reinforcing layer was disposed between the inner and outer belt layers
And a comparative tire 2 in which the belt reinforcing layer was not provided in the tire 2 of the present invention, and a conventional tire 2 in which three belt layers in which the cut ends of the reinforcing cords were located at the belt layer edge were provided.

In each of the test tires, a steel cord (1 × 3 (0.25 mm), 40 cords / 5
cm) and the angle of inclination is 24 °. For the belt reinforcing layer in the tire 2 of the present invention, amorphous nylon (trade name: Novamid × 21 / manufactured by Mitsubishi Chemical Corporation) was used. In this case, a belt reinforcing layer was prepared by extrusion molding of a usual thermoplastic resin. The Young's modulus of this reinforcing layer material is 2
00MPa and thickness is 1.8mm.

The adhesive between the belt reinforcing layer and the rubber material was prepared by applying Chemlock 234B (manufactured by Lord Far East) to the belt reinforcing layer in advance. Each of the test tires was evaluated for exercise performance and tire weight in the same manner as described above, and was also evaluated for belt durability. The results shown in Table 2 were obtained. However, the numerical values in Table 2 are index values based on the conventional tire 2. Belt durability Each test tire was mounted on a rim with a rim size of 13 x 5.0 J, the air pressure was set to 200 kPa, a single drum test was performed at high speed, and the durability until separation occurred at the edge of the belt layer was measured. The result was compared with the conventional tire 2 by 10
The evaluation was made with an index value of 0. The larger the value, the better the edge separation resistance of the belt layer.

[0044]

[Table 2]

As is clear from Table 2, the tire 2 of the present invention
It can be seen from the above that a good kinetic performance can be secured while improving the edge separation resistance of the belt layer and minimizing the increase in weight. The exercise performance is good if it is 95 or more.

[0046]

As described above, according to the present invention, the inner and outer belt layers embedded on the outer peripheral side of the carcass layer of the tread portion are extended by bending the reinforcing cord from one side to the other at the edge of the belt layer. And a belt reinforcing layer disposed between the inner and outer belt layers, and the belt reinforcing layer is formed by blending a thermoplastic resin having a Young's modulus of 10 to 1500 MPa or a thermoplastic resin component and an elastomer component. Because it is composed of a thermoplastic elastomer composition,
It is always possible to ensure good exercise performance while improving the edge separation resistance of the belt layer and minimizing the increase in weight.

[Brief description of the drawings]

FIG. 1 is a tire meridian sectional view showing an example of a pneumatic tire of the present invention.

FIG. 2 is an enlarged cutaway plan view showing a main part of FIG. 1;

FIG. 3 is an explanatory view showing an example of a method for forming a belt layer in which the belt reinforcing layer of FIG. 1 is provided.

FIG. 4 is a perspective view of an essential part showing an example of a belt layer interposed with a belt reinforcing layer obtained by the molding method of FIG. 3;

[Explanation of symbols]

Reference Signs List 1 tread portion 2 bead portion 3 sidewall portion 4 carcass layer 5 bead core 6 bead filler 7 belt layer 7A inner belt layer 7B outer belt layer 8 belt reinforcing layer T tire circumferential direction f reinforcing cord

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Morikawa 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Factory

Claims (6)

[Claims] An inner and outer belt layer embedded on the outer side of a carcass layer of a tread portion has a helical winding structure in which a reinforcing cord is folded back from one side to the other at an edge portion of the belt layer and extends. A belt reinforcement layer is disposed between the inner and outer belt layers, and the belt reinforcement layer has a Young's modulus of 10 to 10.
A pneumatic tire comprising a thermoplastic resin of 1500 MPa or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component. 2. The pneumatic tire according to claim 1, wherein at least one belt reinforcing layer is disposed, and a total thickness of the belt reinforcing layer is 0.5 to 6 mm. 3. The pneumatic tire according to claim 1, wherein the reinforcing cords of the inner and outer belt layers are formed of organic fiber cords. 4. The pneumatic tire according to claim 1, wherein the reinforcing cords of the inner and outer belt layers are formed of steel cords. 5. The pneumatic tire according to claim 4, wherein the thickness of the belt reinforcing layer is 1.0 mm or more. 6. The reinforcing cord is attached to the tire in a circumferential direction of the tire.
The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is oriented at an angle of 5 to 75 °.