JP5265221B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire, and more particularly to a motorcycle tire capable of improving handling properties without impairing workability and grip performance during manufacture.

  With regard to the motor performance of motorcycle tires, improvement in handling properties has been demanded. Regarding handling properties, (1) the steering operation is light and (2) the vehicle responsiveness to the steering operation is good. In order to achieve the above performances (1) and (2), various ideas have been made such as adopting a tread pattern having a specific shape for the tread portion of the tire or applying a tread rubber having specific physical properties. ing. For example, in Japanese Patent Application Laid-Open No. 11-315167 (Patent Document 1), it is considered that if the hardness and the elastic modulus at 300% strain of the rubber composition are large, the handleability is good. On the other hand, JP-A-7-90124 (Patent Document 2) discloses a method in which a rubber composition highly filled with a resin and a softening agent is applied to a tread portion and the adhesive effect of the resin is utilized in a grip. However, the handling property has not been studied.

JP-A-11-315167 JP-A-7-90124

  However, when the present inventors examined, it turned out that the above linear relationship does not exist between handling property and an elasticity modulus. Further, when the handling property was further examined, it was found that the responsiveness of the vehicle to the steering operation tends to deteriorate the handling property whether it is too low or too high. Therefore, as described in JP-A-11-315167, the technique of improving the handleability by increasing the hardness of the rubber composition and the elastic modulus at 300% strain is a means for improving the handleability. It was not clear.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motorcycle tire capable of reliably improving handling properties without impairing workability and grip performance during production.

  As a result of intensive studies to achieve the above object, the present inventors have arranged a tread rubber having a shear storage elastic modulus (G ′) within a predetermined range in the tread portion, so that workability at the time of manufacturing a tire is improved. And it discovered that handling property could be improved reliably, without impairing grip performance, and came to complete this invention.

That is, in the motorcycle tire of the present invention, a tread rubber having a shear storage modulus (G ′) of 7.0 to 8.0 MPa is disposed in the tread portion, and the tread rubber is 1 to 10 parts per 100 parts by mass of the rubber component. It is characterized by using a rubber composition formed by blending part by mass of an alkylphenol acetylene resin.

  The rubber composition used for the tread rubber of the motorcycle tire of the present invention preferably contains a low molecular weight polymer having a rubber component having a weight average molecular weight of 150,000 to 3,000,000 and a weight average molecular weight of 2,000 to 50,000. .

  The rubber composition used for the tread rubber of the motorcycle tire of the present invention preferably further contains 110 parts by mass or less of carbon black with respect to 100 parts by mass of the rubber component.

  According to the present invention, a tread rubber having a shear storage elastic modulus (G ′) within a predetermined range is disposed in the tread portion, and handling properties are reliably improved without impairing workability and grip performance at the time of manufacture. It is possible to provide a motorcycle tire that can be used.

  The present invention is described in detail below. The motorcycle tire of the present invention is characterized in that a tread rubber having a shear storage elastic modulus (G ′) of 6.5 to 8.5 MPa is arranged in the tread portion. If the shear storage modulus (G ′) of the tread rubber disposed in the tread portion is 6.5 to 8.5 MPa, the vehicle response to steering operation regardless of the type of polymer and other compounds used in the tread rubber It is possible to improve the handleability significantly. Moreover, the shear storage elastic modulus (G ′) of the tread rubber is maintained in a low range, and the workability and grip performance at the time of manufacture are not deteriorated. When the shear storage modulus (G ′) of the tread rubber is less than 6.5 MPa, the vehicle response to the steering operation is too slow, and when it exceeds 8.5 MPa, the vehicle response to the steering operation is too fast. In this case, the handleability is lowered. The shear storage modulus (G ′) of the tread rubber is preferably 7.0 to 8.0 MPa from the viewpoint of improving handling properties.

  Moreover, it is preferable to use the rubber composition formed by mix | blending 1-10 mass parts resin with respect to 100 mass parts of rubber components in the tread rubber arrange | positioned at the said tread part. In the rubber composition used for the tread rubber, the shear storage elastic modulus (G ′) of the tread rubber is within the specified range by setting the compounding amount of the resin to 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. It becomes easy to adjust to. If the amount of the resin is less than 1 part by mass with respect to 100 parts by mass of the rubber component, grip performance may be insufficient. On the other hand, if it exceeds 10 parts by mass, workability during production may be reduced. Further, the amount of the resin is preferably 4 to 7 parts by mass, more preferably 5 to 6 parts by mass with respect to 100 parts by mass of the rubber component.

  The resin that can be used in the rubber composition is generally a thermoplastic resin having a molecular weight of several hundred to several thousand, and is a resin that imparts tackiness by blending with natural rubber or synthetic rubber. And synthetic resins. Specific examples of the natural resin include terpene resins such as α-pinene-based, β-pinene-based, and dipentene-based terpene resins, aromatic modified terpene resins, terpene phenolic resins, hydrogenated terpene resins, and the like. It is done. On the other hand, examples of the synthetic resin include petroleum resins, phenol resins, coal resins, xylene resins, and the like. These resins may be used alone or in combination of two or more.

  In particular, when a phenolic resin is blended in the rubber component as a resin, an excellent improvement in handling properties can be obtained without impairing workability and grip performance during production. Examples of the phenolic resin include alkylphenol formaldehyde resins and rosin-modified products thereof, alkylphenol acetylene resins, alkylphenol resins such as modified alkylphenol resins, terpene phenol resins, and the like, alkylphenol resins are preferred, alkylphenol acetylene resins Resins are more preferred, and pt-butylphenol acetylene resins are particularly preferred. The pt-butylphenol acetylene resin is a resin obtained by polymerizing pt-butylphenol acetylene, and specific examples thereof include trade name Cholecin (manufactured by BASF).

  The rubber component of the rubber composition for tread rubber includes natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), ethylene-propylene-diene rubber. (EPDM), chloroprene rubber (CR), butyl rubber (IIR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), and other synthetic rubbers. These rubber components may be used singly or Two or more kinds may be blended and used.

  The rubber component of the rubber composition for tread rubber preferably has a weight average molecular weight of 150,000 to 3 million. If the weight average molecular weight of the rubber component is less than 150,000, the unvulcanized viscosity is too low, the torque during kneading is not applied, and the kneading may be insufficient. On the other hand, when the weight average molecular weight of the rubber component exceeds 3 million, the viscosity becomes too high and the workability during production tends to be lowered. In addition, a weight average molecular weight can be calculated | required as a value of polystyrene conversion, for example using gel permeation chromatography.

  The rubber composition for tread rubber preferably further contains a low molecular weight polymer having a weight average molecular weight of 2,000 to 50,000. In the rubber composition for tread rubber, when a low molecular weight polymer is further blended, the low molecular weight polymer and the rubber component are entangled with each other, thereby improving the grip performance. Further, the blending amount of the low molecular weight polymer is preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. When the blending amount of the low molecular weight polymer exceeds 20 parts by mass with respect to 100 parts by mass of the rubber component, the Mooney viscosity of the rubber composition tends to be too low, and the workability during production tends to decrease.

  The low molecular weight polymer preferably has a weight average molecular weight of 2,000 to 50,000. If the weight average molecular weight of the low molecular weight polymer is less than 2,000, the grip performance may be lowered. On the other hand, if it exceeds 50,000, the workability of the rubber composition tends to be lowered. In addition, a weight average molecular weight can be calculated | required as a value of polystyrene conversion, for example using gel permeation chromatography.

  The low molecular weight polymer is produced, for example, by copolymerizing an aromatic vinyl compound and a conjugated diene compound or polymerizing a conjugated diene compound. Here, examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene and 2,4,6-trimethylstyrene. These aromatic vinyl compounds may be used alone or in combination of two or more. On the other hand, examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. These conjugated diene compounds may be used alone or in combination of two or more.

  The low molecular weight polymer is obtained, for example, by polymerizing the aromatic vinyl compound and the conjugated diene compound by anionic polymerization using a lithium-based polymerization initiator in the presence of an ether or a tertiary amine in a hydrocarbon solvent. can get. Here, the hydrocarbon solvent is not particularly limited, but cycloaliphatic hydrocarbons such as cyclohexane, methylcyclopentane, cyclooctane, propane, butane, pentane, hexane, heptane, octane, decane, etc. Aliphatic hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and ethylbenzene can be used. These hydrocarbons may be used alone or in combination of two or more. The lithium-based polymerization initiator is preferably an organic lithium compound, and the organic lithium compound is preferably n-butyl lithium, sec-butyl lithium, t-butyl lithium or tetramethylene dilithium, and n-butyl lithium. Is particularly preferred. The polymerization reaction for obtaining the low molecular weight polymer can be performed by either a batch polymerization method or a continuous polymerization method. The polymerization temperature in the polymerization reaction is preferably in the range of 0 to 130 ° C. The polymerization reaction can be carried out by any polymerization method such as isothermal polymerization, temperature rising polymerization and adiabatic polymerization. Furthermore, when performing the polymerization, an allene compound such as 1,2-butadiene may be added in order to prevent the formation of a gel in the reaction vessel.

  The rubber composition for tread rubber preferably further contains 110 parts by mass or less of carbon black with respect to 100 parts by mass of the rubber component in addition to the resin and the low molecular weight polymer. When the compounding amount of the carbon black exceeds 110 parts by mass with respect to 100 parts by mass of the rubber component, the shear storage elastic modulus (G ′) of the rubber composition is increased, and sufficient handling properties cannot be ensured. Here, the carbon black is not particularly limited, and examples thereof include FEF, SRF, HAF, ISAF, and SAF grades. The carbon black is preferably carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or more. By blending carbon black, various physical properties of the rubber composition can be improved, but those of HAF, ISAF, and SAF grades are more preferable from the viewpoint of improving the wear resistance.

  In the rubber composition for tread rubber, in addition to the rubber component, a resin, a low molecular weight polymer, carbon black, and other fillers commonly used in the rubber industry, such as softeners, silica and other fillers Antiaging agents, vulcanization accelerators, vulcanizing agents, and the like can be appropriately blended depending on the purpose. As these compounding agents, commercially available products can be suitably used. The rubber composition for a tread rubber can be produced by blending various compounding agents appropriately selected as necessary with a rubber component, kneading, heating, extruding and the like.

  Next, the motorcycle tire of the present invention will be described in detail with reference to the drawings. The motorcycle tire shown in FIG. 1 extends in a toroidal shape between a pair of left and right bead portions 1 and a pair of sidewall portions 2, a tread portion 3, and a bead core 4 embedded in the bead portion 1. A radial carcass 5 and a belt 6 composed of a plurality of belt layers disposed on the outer side in the tire radial direction at the crown portion of the radial carcass 5, wherein the tread portion 3 has a shear storage modulus (G ′). The tread rubber 7 of 6.5 to 8.5 MPa is disposed, and handling properties are greatly improved without impairing workability and grip performance at the time of manufacture.

  The members other than the tread rubber 7 of the motorcycle tire of the present invention are not particularly limited, and known members can be used. Moreover, as gas with which the motorcycle tire of the present invention is filled, an inert gas such as nitrogen, argon, helium, etc. can be used in addition to air having normal or oxygen partial pressure adjusted.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  A rubber composition for a tread rubber having a formulation shown in Table 1 was prepared according to a conventional method. Moreover, about the obtained rubber composition, the shear storage elastic modulus (G ') was measured with the following method, and also workability | operativity at the time of manufacture, grip performance, and handling property were evaluated. The results are shown in Table 1.

(1) Shear storage elastic modulus (G ′)
For the vulcanized rubber obtained by vulcanizing the above rubber composition at 145 ° C. for 30 minutes, using the Ares viscoelasticity testing device manufactured by Rheometrics, the condition of 20 ° C., 10 Hz, and strain 1% is applied. The shear storage modulus (G ′) was measured.

(2) Workability at the time of manufacture The workability at the time of tire manufacture was evaluated in an actual factory line. In Table 1, ◯ indicates that there was no problem in the work during tire production, particularly the kneading of the rubber composition for tread rubber, and x indicates that there was a problem in the work during tire production.

(3) Grip performance and handling properties Using the rubber composition described above as a tread rubber, a motorcycle tire having the structure shown in Fig. 1 and having a size of 120 / 70ZR17 was produced. The obtained tires were assembled on the front wheels of the actual vehicle, traveled on a test course, and the superiority or inferiority was judged by feeling evaluation of a specialized driver. The grip performance and handling performance of the tire of Comparative Example 1 were each indicated as 100 and indicated as an index. It shows that grip performance and handling property are so favorable that an index value is large.

* 1 Styrene-butadiene copolymer rubber, SBR1500 from JSR, weight average molecular weight in terms of polystyrene = 450,000.
* 2 Polybutadiene rubber, BR01 made by JSR, weight average molecular weight in terms of polystyrene = 550,000.
* 3 Colesin, manufactured by BASF.
* 4 Styrene-butadiene copolymer, polystyrene equivalent weight average molecular weight = 10000.
* 5 Noxeller CZ manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
* 6 Sunseller DG manufactured by Sanshin Chemical Industry Co., Ltd.

  From Table 1, the tire of the example in which the rubber composition having a shear storage elastic modulus (G ′) of 6.5 to 8.5 MPa is disposed in the tread portion is excellent in workability and grip performance at the time of manufacture, and has handling properties. It turns out that it can improve significantly.

1 is a cross-sectional view of an example of a motorcycle tire of the present invention.

Explanation of symbols

1 Bead part 2 Side part 3 Tread part 4 Bead core 5 Radial carcass 6 Belt 7 Tread rubber

Claims (3)

A tread rubber having a shear storage modulus (G ′) of 7.0 to 8.0 MPa is disposed in the tread portion, and 1 to 10 parts by mass of an alkylphenol acetylene resin is blended with the tread rubber with respect to 100 parts by mass of the rubber component. A tire for a motorcycle characterized by using the rubber composition . The rubber composition is that 150,000 to 3,000,000 weight average molecular weight of the rubber component, for a motorcycle according to claim 1, further weight-average molecular weight is characterized in that it comprises a low molecular weight polymer of 2,000 to 50,000 tire. The motorcycle tire according to claim 1 or 2 , wherein the rubber composition further includes 110 parts by mass or less of carbon black with respect to 100 parts by mass of a rubber component.

Images