JP3568322B2 - Pneumatic tire - Google Patents

Description

【００３２】
表１から明らかなように、本発明範囲外のヤング率の５０ＭＰａ未満、もしくは超５００ＭＰａの樹脂からなる樹脂フィルムを用いた場合には、耐久性がわるい（比較例１、２）。また、ビードフィラーを配置した従来タイヤ２に比して、ビードフィラーを配置することのない本発明タイヤ１〜３は、タイヤ幅方向剛性にも優れている。
【００３３】
【発明の効果】
以上説明したように本発明によれば、ビード部に、ビードフィラーを配置することなしに、カーカス層の巻き上げ端部にヤング率５０〜５００ＭＰａの熱可塑性樹脂からなる樹脂フィルムを積層したので、耐久性を低下させることなく軽量化が可能となる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一例の子午線方向半断面図である。
【図２】本発明の空気入りタイヤのビード部構造の他の一例を示す子午線方向断面図である。
【符号の説明】
１ ビード部 ２ カーカス層 ３ ビードコア ４ トレッド
５ｄ 下側ベルト層 ５ｕ 上側ベルト層 ６ 樹脂フィルム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire capable of reducing weight without reducing durability.
[0002]
[Prior art]
In recent years, bead filler structures have been proposed in which bead fillers are reduced in size or filler-free to satisfy the demand for tire weight reduction. However, in such a bead portion structure, the durability is reduced unless the thickness of the side tread is set to a conventional value or is not increased, so that a sufficient weight reduction cannot be achieved. Further, in this bead portion structure, a reinforcing layer made of a reinforcing cord such as a steel cord or a nylon cord is also arranged on the side portion to ensure durability, but it is arranged when the reinforcing layer is arranged in this way. There was a problem that the weight increased by the amount.
Therefore, the reduction in tire weight and the durability due to the reduction in the weight of the bead portion are in a trade-off relationship, and it is difficult to achieve both.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire that can be reduced in weight without reducing durability.
[0004]
[Means for Solving the Invention]
The present invention includes mounting a carcass layer between a pair of left and right bead portions, folding the end portion of the carcass layer outward from the tire inside without arranging a bead filler around a bead core, and winding up the carcass layer. and wherein the laminated resin film comprising a thermoplastic resin Young's modulus 50~500MPa so as to straddle the radially inner and outer side.
[0005]
In order to arrange a resin film made of a thermoplastic resin having a Young's modulus of 50 to 500 MPa, which is significantly higher than that of rubber in place of the conventional bead filler, in the bead portion, while increasing the tire width direction rigidity of the bead portion, This resin film can play the role of a bead filler to make the bead portion sit well on the rim. Further, in addition to omitting the bead filler, this resin film is made of a thermoplastic resin whose Young's modulus is much higher than that of rubber, so that the entire bead portion can be made thinner, and the tire can be reduced in weight.
[0006]
Furthermore, since this resin film is arranged so as to straddle the inside and outside in the tire radial direction at the winding end of the carcass layer, it is possible to prevent stress from being concentrated on the winding end, so that Separation can be prevented, and durability can be improved.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In the pneumatic tire of the present invention, as shown in FIG. 1, a carcass layer 2 is mounted between a pair of left and right bead portions 1, 1, and an end of the carcass layer 2 is formed around the bead core 3 in the bead portion 1. It is folded up from inside to outside. Outside the carcass layer 2 in the tread 4, two belt layers, a lower belt layer 5d and an upper belt layer 5u having a width smaller than the lower belt layer 5d, are arranged around the tire in the tire circumferential direction. Have been.
[0008]
In the bead portion 1, a bead filler having a hardness higher than that of a peripheral rubber having a triangular cross section which is usually arranged on the tire radial direction outer side of the bead core 3 is not arranged, and the carcass layer 2 has a carcass layer 2 in which the winding portion 2a is not wound up. It extends in the direction of the tread 4 along the layer 2. In the bead part 1, the resin film 6 is disposed so as to cover the winding terminal 2b of the carcass layer 2. The arrangement of the resin film 6 may be outside the winding terminal 2b as shown in FIG. 1 or between the winding terminal 2b and the unwound carcass layer 2 as shown in FIG. This is because the resin film 6 only needs to be disposed so as to straddle the winding end of the carcass layer inward and outward in the tire radial direction.
[0009]
The resin film 6 may have one end extending to the vicinity of the bead core 3 and the other end extending to the vicinity of the lower belt layer 5d. The length a of the resin film 6 in the direction of the bead core from the position of the winding terminal 2b of the carcass layer 2 and the length b of the resin film 6 in the direction of the tread 4 from the position of the winding terminal 2b of the carcass layer 2 are respectively a ≧ It is preferable that 10 mm and b ≧ 10 mm. The thickness of the resin film 6 is preferably from 0.1 to 3.0 mm, and more preferably from 0.1 to 1.0 mm.
[0010]
A plurality of the resin films 6 may be arranged. For example, the resin film 6 may be arranged outside the winding terminal 2b as shown in FIG. 1 and between the winding terminal 2b and the unwound carcass layer 2 as shown in FIG. May be arranged.
Further, the resin film 6 is made of a thermoplastic resin Young's modulus 50～500MPa. If the Young's modulus is less than 50 MPa, the rigidity in the tire width direction decreases. If the Young's modulus is more than 500 MPa, the rigidity becomes too high, the material is easily broken, the durability is reduced, and the tire is broken.
[0011]
The thermoplastic resin may have a Young's modulus of 50 to 500 MPa. For example, 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 N-alkoxyalkylated products thereof, for example, methoxymethyl of 6-nylon Methoxymethylated 6-610-nylon, methoxymethylated 612-nylon, Ester-based resins (for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PE10), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, Aromatic polyesters such as polyoxyalkylenediimidic acid / polybutylate terephthalate copolymer), polynitrile resins (for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / Styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resins (eg, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl alcohol Resin (eg, vinyl acetate, 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), cellulosic resin (eg, cellulose acetate, cellulose acetate butyrate), fluororesin (eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF)) , Polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer), and imide-based resin (for example, aromatic polyimide (PI)).
[0012]
Further, as the resin film 6 used in the present invention, a film obtained by blending an elastomer with the above-mentioned thermoplastic resin may be used.
As the elastomer component that can be blended with the thermoplastic resin, the type and amount of the elastomer component may be used as long as the composition is formed in a state of being blended with the thermoplastic resin component, and as a result, the film has a Young's modulus of 50 to 500 MPa. Is not particularly limited.
[0013]
Examples of elastomers to be blended with the thermoplastic resin include diene rubbers and hydrogenated products thereof (for example, NR, IR, epoxidized natural rubber, SBR, BR (high-dis BR and low-cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubber (eg, ethylene propylene rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer), Acrylic rubber (ACM), ionomer, halogen-containing rubber (for example, bromide of Br-IIR, CI-IIR, isobutylene paramethylstyrene copolymer (Br-IPMS), CR, hydrin rubber (CHR.CHC), chlorosulfonation Polyethylene (CSM), chlorinated polyethylene (CM), Murray Acid-modified chlorinated polyethylene (M-CM)), silicone rubber (eg, methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg, polysulfide rubber), fluorine rubber (eg, vinylidene fluoride) Rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (for example, styrene-based elastomer, olefin-based elastomer, ester-based elastomer, urethane-based rubber) Elastomer, polyamide-based elastomer) and the like, and two or more kinds may be used.
[0014]
When the compatibility between the thermoplastic resin and the elastomer component is different, it is preferable to add an appropriate compatibilizer as the third component. By mixing the compatibilizer into the system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the rubber particles forming the dispersion layer become finer, so that the properties of both components are more improved. It will be effectively expressed. Such a compatibilizer is 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, an amino group capable of reacting with the thermoplastic resin or the elastomer component. It can have a copolymerized structure having a group, an oxazoline group, a hydroxyl group and the like. These may be selected depending on the types 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: EPDM / Examples include 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 with respect to 100 parts by weight of the polymer component (total of the thermoplastic resin and the elastomer component).
[0015]
When blending the thermoplastic resin and the elastomer, the composition ratio of the thermoplastic resin (A) and the elastomer component (B) is not particularly limited, and is appropriately determined depending on the balance between the thickness of the film, air permeability, and flexibility. The preferred range is 10/90 to 90/10, more preferably 15/85 to 90/10, by weight ratio (A) / (B).
[0016]
The polymer composition (resin film 6) according to the present invention comprises, in addition to the above essential polymer components, other polymers such as the above-mentioned compatibilizer polymer within a range not to impair the necessary properties of the tire polymer composition of the present invention. Can be mixed. The purpose of mixing the other polymer is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the film formability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material used include polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, SBS, and polycarbonate (PC). In addition, olefin copolymers such as polyethylene and polypropylene, maleic acid-modified products thereof, and glycidyl group-introduced products thereof can also be mentioned. The polymer composition according to the present invention may further include a filler (calcium carbonate, titanium oxide, alumina, etc.), a reinforcing agent such as carbon black and white carbon, a softener, a plasticizer, Processing aids, pigments, dyes, antioxidants and the like can be arbitrarily compounded as long as the requirements for the air permeability coefficient and Young's modulus are not impaired.
[0017]
Further, 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, and for example, 0.5 to 4 phr. [Parts by weight per 100 parts by weight of rubber component (polymer)] can be used.
[0018]
Organic peroxide-based vulcanizing agents include benzoyl peroxide, t-butyl hydroperoxide, 2,4-bichlorobenzoyl peroxide, 2, Te-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, and Fe-dimethyl. Examples of thiourea-based vulcanization accelerators such as dithiocarbamate and pipecoline pipecolyl dithiocarbamate include ethylenethiourea and diethylthiourea.
[0019]
As the vulcanization accelerating auxiliary, a general rubber auxiliary may be used in combination, for example, zinc white (about 5 phr), stearic acid, oleic acid and Zn salt thereof (about 2 to 4 phr). Etc. can be used.
In a method for producing a thermoplastic elastomer composition, a thermoplastic resin component and an elastomer component (unvulcanized product in the case of rubber) are melt-kneaded in advance by a twin-screw kneading extruder or the like to form a continuous phase (matrix phase). By dispersing an elastomer component in a thermoplastic resin as a dispersed phase (domain). 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 it is preferable to mix them 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 twin-screw kneading extruder or the like can be used. Among them, for kneading the thermoplastic resin and the elastomer component and for dynamic vulcanization of the elastomer component, it is preferable to use a twin-screw kneading extruder. Further, two or more kinds of kneaders may be used to knead sequentially. As the conditions for the melt-kneading, the temperature may be at least the temperature at which the thermoplastic resin melts. Further, the shear rate at the time of kneading is preferably 1000 to 7500 sec ^-1 . The total kneading time is preferably from 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after the addition is preferably from 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.
[0020]
The 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, rubber elasticity can be maintained and thermoplastic processing can be performed, and sufficient rigidity is obtained by the flexibility of the film as the belt reinforcing layer and the effect of the resin layer as the continuous phase. In addition to being able to be given together, regardless of the amount of the elastomer component, at the time of molding, it is possible to obtain molding workability equivalent to that of a thermoplastic resin, and therefore, a usual resin molding machine, that is, extrusion molding, or calender molding It becomes possible to form a film.
[0021]
Adhesion between these films and the rubber layer opposite to each other is performed by applying an adhesive obtained by dissolving a polymer such as a normal rubber-based, phenolic resin-based, acrylic copolymer-based, or isocyanate-based polymer and a crosslinking agent to a solvent, and vulcanizing and molding Bonding by heat and pressure at the time, or by bonding an adhesive resin such as styrene butadiene styrene copolymer (SBS), ethylene ethyl acrylate (EEA), and styrene ethylene butylene block copolymer (SEBS) together with a thermoplastic film. There is a method in which a multilayer film is prepared by extrusion or lamination and then adhered to a rubber layer during vulcanization. Examples of the solvent-based adhesive include a phenol resin-based resin (Chemrock 220, Road Co., Ltd.), a chlorinated rubber-based resin (Chemrock 205, Chemlock 234B), and an isocyanate-based resin (Chemrock 402).
[0022]
【Example】
With respect to the following tires (the present tires 1 to 3, the comparative tires 1 and 2, and the conventional tires 1 and 2), the bead weight, durability, and tire width direction rigidity were measured as follows. Table 1 shows the results.
Inventive tire 1
Tire size 175/70 R13 82S. The bead part structure shown in FIG. The resin film 6 is made of a thermoplastic elastomer having a Young's modulus of 50 MPa. The thickness of the resin film 6 is 0.3 mm and the width is 60 mm (a = 30 mm, b = 30 mm). The thermoplastic elastomer of this example is prepared by previously mixing nylon 11 (Atochem Rilsan BMNO) and Br-IPMS (Exxon 89 Expro 89-4) with a 50/50 ratio using a twin-screw kneader. After the elastomer component is sufficiently dispersed in the components, zinc white, zinc stearate, and stearic acid are added as vulcanizing agents to 0.4 parts by weight, 2 parts by weight, and 1 part by weight, respectively, based on 100 parts by weight of the elastomer. In addition, it was prepared by dynamically vulcanizing and pelletizing.
[0023]
Further, the pellets were formed into a film using a conventional thermoplastic resin T-die extruder.
Invention tire 2
Tire size 175/70 R13 82S. The bead part structure shown in FIG. The resin film 6 is made of a nylon 6,66 copolymer (Toray Amilan CM 6021) having a Young's modulus of 250 MPa. The thickness of the resin film 6 is 0.3 mm and the width is 60 mm (a = 30 mm, b = 30 mm).
[0024]
The material was formed into a film by T-die extrusion of a usual thermoplastic resin.
Invention tire 3
Tire size 175/70 R13 82S. The bead part structure shown in FIG. The resin film 6 is made of a nylon 12 (Atochem Rilsan AMNO) resin having a Young's modulus of 500 MPa. The thickness of the resin film 6 is 0.3 mm and the width is 60 mm (a = 30 mm, b = 30 mm).
[0025]
The material was formed into a film by T-die extrusion of a usual thermoplastic resin.
Comparative tire 1
Tire size 175/70 R13 82S. The bead part structure shown in FIG. The resin film 6 is made of a thermoplastic elastomer having a Young's modulus of 40 MPa. The thickness of the resin film 6 is 0.3 mm and the width is 60 mm (a = 30 mm, b = 30 mm).
[0026]
The thermoplastic elastomer of this comparative example is the one in which the ratio of nylon 11 and Br-IPMS described in the tire 1 of the present invention is 40/60, and the thermoplastic elastomer production method and film forming method are completely the same as the tire 1 of the present invention. Performed similarly.
Comparative tire 2
Tire size 175/70 R13 82S. The bead part structure shown in FIG. The resin film 6 is made of PBT (polyplastics duranex 600 FP) having a Young's modulus of 600 MPa. The thickness of the resin film 6 is 0.3 mm and the width is 60 mm (a = 30 mm, b = 30 mm).
[0027]
The film was formed by T-die extrusion of a usual thermoplastic resin.
Conventional tire 1
Tire size 175/70 R13 82S. A bead filler having a triangular cross section (bead filler having a base of 6.5 mm and a height of 25 mm) is disposed outside the bead core in the tire radial direction (the position of the resin film 6 in FIG. 1). A nylon reinforcing layer having a length of 1.05 mm, a width of 50 mm, and 38 ends is arranged.
[0028]
Conventional tire 2
Tire size 175/70 R13 82S. A bead filler having a triangular cross section is disposed outside the bead core in the tire radial direction (position of the resin film 6 in FIG. 1) (bead filler having a base of 6.5 mm and a height of 40 mm).
Method of measuring bead weight :
The weight of the reinforcing layer and bead filler before molding of each test tire was measured. The result is shown as an index with the conventional tire 1 being 100. The smaller the value, the lighter.
[0029]
Durability measurement method :
According to JIS D 4230, the vehicle was driven under the conditions of 180 kPa and 81 km / h, and the state of the bead portion at 2754 km was observed. "Passed" means that the vehicle traveled 2754 km without tire failure. "Fail" means that a tire failure occurred less than 2754 km, and the mileage at the time of occurrence of the failure is added.
[0030]
Method of measuring tire width direction rigidity :
Each test tire was mounted on a JATMA standard rim, the air pressure was set to 200 kPa, the amount of lateral deflection of the tire at a load of 3.43 KN was measured, and calculated from a load-deflection curve. The result is shown by an index with the conventional tire 2 being 100. Larger values indicate higher rigidity.
[0031]

[0032]
As is clear from Table 1, when a resin film made of a resin having a Young's modulus less than 50 MPa or exceeding 500 MPa outside the range of the present invention is used, the durability is poor (Comparative Examples 1 and 2). In addition, the tires 1 to 3 of the present invention in which no bead filler is disposed are superior to the conventional tire 2 in which the bead filler is disposed in the tire width direction rigidity.
[0033]
【The invention's effect】
According to the present invention described above, the bead portion, without placing a bead filler, since the laminated resin film comprising a thermoplastic resin Young's modulus 50~500MPa the winding end portion of the carcass layer, It is possible to reduce the weight without reducing the durability.
[Brief description of the drawings]
FIG. 1 is a half sectional view in the meridian direction of an example of a pneumatic tire of the present invention.
FIG. 2 is a meridional section view showing another example of the bead portion structure of the pneumatic tire of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bead part 2 Carcass layer 3 Bead core 4 Tread 5d Lower belt layer 5u Upper belt layer 6 Resin film

Claims (5)

A carcass layer is mounted between a pair of left and right bead portions, and the end of the carcass layer is turned from the inside of the tire to the outside without arranging a bead filler around a bead core. inside and a pneumatic tire of the resin film is laminated to become an outer astride a thermoplastic resin Young's modulus 50～500MPa. Wherein a thickness of the resin film is 0.1 ~3.0mm, and the extension length b from the terminal of the winding end portion of the carcass layer to extend the length a and the outer side in the tire radial direction from the terminal to the tire radial direction inside each 2. The pneumatic tire according to claim 1, wherein a ≧ 10 mm and b ≧ 10 mm. The thermoplastic resin is at least one selected from the group consisting of a polyamide resin, a polyester resin, a polynitrile resin, a polymethacrylate resin, a polyvinyl resin, a cellulose resin, a fluorine resin and an imide resin. 3. The pneumatic tire according to 1 or 2. The pneumatic tire according to claim 1, 2 or 3, wherein the resin film contains an elastomer. The pneumatic tire according to claim 4, wherein the elastomer is at least one selected from the group consisting of a diene rubber and a hydrogenated product thereof, an olefin rubber, a halogen-containing rubber, a sulfur-containing rubber, a fluororubber, and a thermoplastic elastomer.

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