JP2001001715A - Pneumatic tire for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance pneumatic tire for a two-wheeled vehicle that is excellent in maneuverability and turnability with a good balance between them. SOLUTION: This tire is at least provided with a spiral belt layer made of a cord arranged inside a tread in the circumferential direction of the tire and a carcass cord to be combined with the spiral belt layer. This carcass cord is substantially made of polyethylene-2,6-naphthalate. Modes such as a carcass cord having a tensile elastic modulus of 7012 to 11670 MPa at 50±5 deg.C, a carcass cord formed of yarn twisted with raw yarn substantially made of polyethylene-2, 6-naphtalate, and a carcass cord having a total index of decitex 2200 to 5010 are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for a motorcycle, and more particularly, to a high-performance pneumatic tire for a motorcycle having excellent maneuverability and turning performance and a good balance between them.

[0002]

2. Description of the Related Art As a carcass cord for a pneumatic tire for a motorcycle, maneuverability (reaction of turning in a state close to a driver's will), that is, followability (linearity) with respect to handling at the time of turning and turning (at the time of turning). The shape of the ground contact surface is unlikely to change due to the undulation of the road surface or the reaction force from the road surface, and there is little sudden behavior contrary to the driver's will and little blurring of the cornering force), that is, the ability to follow the contact surface when turning. Excellent is required. The maneuverability and the turning property are contradictory in terms of elasticity of the fiber material of the carcass cord, and a high elasticity fiber is preferable in terms of improving the maneuverability, and a low elasticity fiber is preferable in terms of improving the turning property. Fibers are preferred. Therefore, in order to improve the maneuverability and the turning performance, it is extremely important to select a fiber material of the carcass cord.

Conventionally, organic fibers such as nylon, polyester, rayon, and aramid are generally used as the material of the carcass cord. Among them, rayon has been particularly preferably used. In the case of the carcass cord made of rayon, the maneuverability is good due to its high elasticity, and the turning property is also good. The reason why the turning property is good is that the rayon is good at the constant stress repeated input from the road surface at the time of ordinary running at about 50 ° C. which is the average temperature of the carcass cord in the tire at the time of ordinary running. This is because it has an excellent hysteresis loss characteristic. Regarding the hysteresis loss characteristics, a crown portion with a small tension load (near the center in the tire width direction)
, The hysteresis loss characteristic of the carcass cord is highly correlated with the grounding property to the road surface, and the better the hysteresis loss characteristic, the better the grounding property to the road surface and the better the turning property.

However, in the case of a carcass cord made of rayon, there is a problem that waste liquid generated in the manufacturing process pollutes the environment. In addition, since rayon has high hygroscopicity, strict water management is required in the carcass cord manufacturing process, and the handling in production is inferior,
If the moisture management is not sufficient, there is a problem that the adhesion between the carcass cord and the rubber covering the carcass cord is deteriorated. As a result, there are problems such as a decrease in durability, a decrease in modulus strength, and a decrease in the maneuverability of a pneumatic tire for a motorcycle.

Therefore, there has been a demand for the development of a pneumatic motorcycle tire which solves the above-mentioned problems in the carcass cord of rayon without impairing the maneuverability of the pneumatic tire for motorcycle using a carcass cord made of rayon. At present, such pneumatic tires for motorcycles have not been provided yet.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems, to meet the above-mentioned demands, and to achieve the following objects. That is, an object of the present invention is to provide a high-performance pneumatic tire for motorcycles that is excellent in maneuverability and turning performance and that has a good balance between them.

[0007]

Means for solving the above problems are as follows. That is, <1> at least a spiral belt layer formed of a cord arranged inside the tread and in the tire circumferential direction, and a carcass cord combined with the spiral belt layer, wherein the carcass cord is And a pneumatic tire for motorcycles, which is substantially formed of polyethylene-2,6-naphthalate. <2> The above <1>, wherein the tensile modulus of the carcass cord at 50 ± 5 ° C. is 6660 to 11770 MPa.
2. The pneumatic tire for a motorcycle according to item 1. <3> The pneumatic tire for a motorcycle according to <1> or <2>, wherein the carcass cord is formed of a twisted yarn of a raw yarn substantially formed of polyethylene-2,6-naphthalate. <4> The pneumatic tire for a motorcycle according to <3>, wherein a twist coefficient (R) of the twisted yarn represented by the following formula is 1440 to 2660. Twist coefficient (R) = N × √ (0.9D) where N is the number of twists (twice / 10c
m), and D represents the total display decitex of the carcass code. <5> The total display decitex of the carcass cord is 22
The pneumatic tire for a motorcycle according to any one of <1> to <4>, wherein the tire is 00 to 5010. <6> The rubber coated on the carcass cord has a tensile stress at 50% elongation of from 0.98 to 1.96, from <1> to <5>.
The pneumatic tire for a motorcycle according to any one of the above.

[0008] In the pneumatic tire for a motorcycle according to <1>, the carcass cord is substantially formed of polyethylene-2,6-naphthalate (hereinafter sometimes referred to as "PEN"). Due to its high elasticity,
The maneuverability (followability during handling) is good,
Since the hysteresis loss characteristic of the carcass cord with respect to the repeated input of constant stress is good, the turning property (following property of the ground contact surface) is good. Further, when manufacturing the carcass cord, there is no environmental pollution due to waste liquid and there is no need for strict water management.

In the pneumatic tire for a motorcycle according to the item <2>, since the carcass cord has a tensile modulus at 50 ± 5 ° C. of 6660-11770 MPa, the maneuverability (followability during handling) is particularly high. Good.

[0010] In the pneumatic tire for a motorcycle according to <3>, the carcass cord may be made of polyethylene-2,6-
Since it is formed of a twisted yarn of a raw yarn substantially formed of naphthalate, it is excellent in the tensile modulus and in the maneuverability.

[0011] The pneumatic tire for a motorcycle according to <4>, wherein the twisting coefficient (R) of the twisted yarn is 14%.
Since it is 40 to 2660, the carcass cord is given an appropriate convergence, and a high level of the tagging effect is obtained. As a result, the adhesion between the carcass cord and the coated rubber is good.

In the pneumatic tire for a motorcycle according to the above <5>, since the total display decitex of the carcass cord is 2200 to 5010, the carcass cord is given an appropriate convergence, and a high-level tagging effect is obtained. Obtained
As a result, the adhesion between the carcass cord and the coated rubber is good.

[0013] In the pneumatic tire for a motorcycle according to the above <6>, the rubber covered with the carcass cord may be made of
Since the tensile stress at the time of 0% elongation is 0.98 to 1.96, the response is excellent.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A pneumatic tire for a motorcycle according to the present invention includes a spiral belt layer formed of a cord disposed inside a tread and in a tire circumferential direction, and a carcass cord combined with the spiral belt layer. The other structure is the same as that of a known pneumatic tire for motorcycles. Note that the pneumatic tire for a motorcycle according to the present invention may be a radial tire or a bias tire.

(Carcass cord) It is necessary that the carcass cord is substantially formed of polyethylene-2,6-naphthalate. In this case, the two-wheeled pneumatic tire including the carcass cord is excellent in the maneuverability and the turning performance, and also has a good balance. The content of polyethylene-2,6-naphthalate in the carcass cord is 85 to 10
It is preferably 0 mol%, more preferably 95 to 100 mol%.

The polyethylene-2,6-naphthalate can be produced according to a known polymerization method such as melt polymerization or solid state polymerization.

The carcass cord is made of polyethylene-
It is formed of 2,6-naphthalate fiber, and the method for producing the fiber is not particularly limited, and a melt spinning method,
A method of fiberizing the polyethylene-2,6-naphthalate by a solution spinning method or the like can be mentioned. Specifically, for example, polyethylene-2,6-naphthalate is produced according to the method described in Example 1 of JP-A-10-88422. Naphthalate fiber (raw yarn) can be produced.

The polyethylene-2,6-naphthalate fiber can be produced, for example, according to the following melt spinning method. That is, a resin chip of the polyethylene-2,6-naphthalate (intrinsic viscosity 0.84) was added to 310
After melting at ℃, the mixture is discharged from a spinneret (diameter 0.6 mm) and spun. The fineness after spinning and drawing was 1111.
Adjust to 1dtex. After passing through the area heated and maintained at 370 ° C. over a length of 400 mm, the discharged yarn is blown at 25 ° C. with a cooling air velocity of 0.3 m / sec and sprayed over a length of 330 mm, and cooled and solidified. Then, after applying the oil agent with an oiling roller, the oil agent is taken up at a speed of 700 m / min. As described above, the polyethylene-2,6-naphthalate is converted into a fiber to obtain a raw yarn.

It is preferable to add an antioxidant to the polyethylene-2,6-naphthalate fiber for the purpose of imparting sufficient durability to heat, oxygen and the like, and if necessary, a matting agent. A known additive such as a pigment, an antistatic agent and the like may be added.

The polyethylene obtained above
2,6-naphthalate fiber (polymer filament)
The tensile strength is usually at least 40 mN / dtex, preferably at least 48 mN / dtex. If the tensile strength is less than 40 mN / dtex, cord breakage during running may occur.

The carcass cord may be formed from one or a bundle of the original yarns of the polyethylene-2,6-naphthalate fiber. In the latter case, For example, the polyethylene-2,6
Priming the naphthalate fiber which is then
A total of three or three strands can be twisted in the opposite direction to obtain a twisted cord.

The above-mentioned twisted cord is, for example,
It is preferable to carry out an adhesive heat treatment using a resorcinol-formalin-based latex adhesive described in Example 1 of JP-A-12503. As the cord physical properties of the twisted cord after the heat treatment for bonding, the elongation (%) under a load of 19.4 mN / dtex (by the method of J1S L1017) is preferably about 2.0 to 3.8%. .

In the case of the above-mentioned twisted cord, the twist coefficient (R) represented by the following formula is preferably from 1440 to 2660, and more preferably from 2020 to 2430. Twist coefficient (R) = N × √ (0.9D) where N is the number of twists (twice / 10c
m), and D represents the total display decitex of the carcass code.

The twist coefficient (R) is 1440 to 266
When it is 0, the carcass cord can be given an appropriate convergence property, a high level tagging effect can be obtained, and the manufacturing handleability is improved. When the twist coefficient (R) is less than 1440, the adhesion between the carcass cord and the coated rubber may be deteriorated. When the twist coefficient (R) exceeds 2660, the elongation of the carcass cord increases and the initial modulus decreases. , The tag effect may be reduced.

The total display decitex (dtex) of the carcass code is preferably 2200 to 5010. If the total display decitex is less than 2200, the rigidity of the motorcycle pneumatic tire is not sufficient, and the total balance as the tire may not be sufficient.If it exceeds 5010, the gauge of the carcass cord increases, The pneumatic tire for a motorcycle may become unnecessarily heavy. Even if the total display decitex is less than 2200, the rigidity of the two-wheeled pneumatic tire can be supplemented to some extent by controlling the number of cords in the carcass cord and the number of layers.

50 ± 5 ° C. of the carcass cord (average temperature of the carcass cord in the tire during normal running)
As the tensile modulus of elasticity is 6660-11770M
Pa is more preferable, and 7012 to 11670 MPa is more preferable. If the tensile modulus is less than 6660 MPa, the turning property may not be sufficient, and 1177
If it exceeds 0 MPa, the rigidity of the pneumatic tire for a motorcycle becomes too high, and the maneuverability, that is, the followability (linearity) to handling during turning may not be sufficient. On the other hand, if the value is within the above-mentioned numerical range, such a case does not occur, which is preferable in that a pneumatic tire for a motorcycle excellent in balance between the maneuverability and the turning performance can be obtained.

The carcass cord may be covered with a rubber. In this case, the covering rubber is not particularly limited, but the tensile stress E at the time of 50% elongation is not limited.
(MPa) is preferably from 0.98 to 1.96. When the tensile stress E (MPa) is less than 0.98, the response tends to be slightly poor, and 1.96.
If it exceeds, the rubber becomes too hard for the tire rigidity,
In some cases, separation may occur.

The carcass cord is combined with a spiral layer. In the pneumatic tire for a motorcycle according to the present invention, for other configurations except the carcass cord,
There is no particular limitation, and it can be designed in the same manner as a known one. The number of layers of the carcass cord is not particularly limited, but is preferably one or two in terms of balance between the weight and rigidity of the two-wheeled pneumatic tire. The spiral layer may be formed of a spiral cord, and the spiral cord may be formed of a twisted original yarn. It is preferable that the raw yarn is formed of a twist yarn of a raw yarn of polyethylene-2,6-naphthalate fiber.

The pneumatic tire for a motorcycle according to the present invention comprising the carcass cord is excellent in the maneuverability and the turning performance and has a good balance.

[0030]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these Examples.

(Examples 1 to 12 and Comparative Examples 1 to 3) One layer of polyethylene-2,6-naphthalate (PEN) carcass cord extending at an angle of 90 ° to the circumferential direction of the tread was formed. Each side edge of the cord was folded from inside to outside around the bead core. Then, one organic fiber (nylon) cord was spirally wound to form a single spiral belt layer having a width substantially equal to the tread width. Therefore, the cord of the spiral belt layer substantially extended in the circumferential direction of the tread. A motorcycle pneumatic tire (tire size: 170 / 60R17) having the above configuration was manufactured.

The carcass cord was formed as follows. That is, first, a polymer comprising 85 mol% or more of polyethylene-2,6-naphthalate was obtained by polymerization. Next, the polymer chips were melt spun. The conditions at this time were a spinning speed of 600 m / min, and a heating cylinder having an atmospheric temperature of 340 ° C. and a length of 44 cm immediately below the spinneret. An oil agent was applied to the spun undrawn yarn with an oiling roller, and the yarn was wound. Next, the obtained undrawn yarn is 1%
After applying the pretension, a shrink heat setting was performed at a relaxation rate of 2.2% between a heated roll and a non-heated roll at 227 ° C., and the roll was wound at 300 m / min.

The temperature of the spinning machine was 300 to 315 ° C. in the latter half of the extruder in which the polymer was melted, and the temperature until discharging from the die was 318 ° C. After passing through the heating tube, the mixture was cooled and solidified at a relative humidity of 65% and a temperature of 25 ° C. over a length of 35 cm. From the above,
A raw yarn of polyethylene-2,6-naphthalate was obtained. Next, this raw yarn was made to have a twist coefficient R of 1440 to 2660 and the number of twists (number of lower twists, number of upper twists) to the values shown in Tables 1 and 2 to obtain a twisted yarn. The carcass cord using the twisted yarn was subjected to an adhesive application and a heat treatment under the following conditions.

First, this twisted cord is referred to as JP-B-63-1.
After dipping in a resorcinol-formalin-based latex adhesive described in Example 1 of JP-A-2503, the treatment temperature in the drying zone was 170 ° C., the treatment time was 60 to 160 seconds, the heat setting zone and the normalizing zone. The processing temperature of 250 to 270 ° C. and the processing time of 60
~ 160 seconds, and both the heat set zone cord tension and the normalizing zone cord tension are 0.2
It was set to 6 to 4.41 mN / dtex. From the above,
A twisted cord was obtained.

The pneumatic tires for motorcycles of the respective Examples and Comparative Examples obtained (tire size: 170 / 60R17)
Was evaluated as follows. The results are shown in Tables 1 and 2. The difference between the tires is only in that the carcass cords shown in Tables 1 and 2 were used. The carcass cord in the first embodiment is
Total display decitex is 1670 dtex / 2, bottom twist is 39 times / 10 cm, top twist is 39 times / 10 cm [twist number is indicated as lower × upper (times / 10 cm) 39 × 39], twist coefficient R is 2254, 50 ± Tensile modulus M at 5 ° C is 6
It was 669 MPa.

<Evaluation>-Tensile modulus-After removing the extra rubber adhering to the cord of the spiral belt layer carefully taken out from the new tire without running without damaging the cord, carefully scraping off the cord with scissors. According to JIS L 1017-1983, a tensile load-elongation curve was drawn at room temperature (25 ± 2 ° C.) using an autograph (manufactured by Shimadzu Corporation). The load axis of this curve was converted to a value obtained by dividing by the total decitex (dtex) number before tension, and rewritten as a stress-elongation curve.
A tangent was drawn at the / dtex load point, and the slope of this tangent was determined. The value obtained by multiplying this value by [9.81 × specific gravity of fiber] was defined as the tensile modulus (MPa).

-Maneuverability and turning performance- Each of the two tires was mounted on the rear wheels of a two-wheeled vehicle with a displacement of 750 cc, and two specialized drivers ran the actual vehicle on a steering stability evaluation test course. The properties were evaluated organoleptically.
Each item was evaluated at 1 to 10 points, and the average score of the evaluations of the two drivers was obtained. In addition, it means that it is excellent, so that a numerical value is large.

[0038]

[Table 1]

[0039]

[Table 2]

From the results in Tables 1 and 2, the following is clear. It is clear that the two-wheeled pneumatic tires of Examples 1 to 12 are excellent in maneuverability and turning performance, have a good balance between them, and have high performance. Also,
In the case of the motorcycle pneumatic tires of Examples 1, 6 and 10 that do not satisfy the conditions defined in claim 2, Examples 2 to 5,
The balance between maneuverability and turning performance was slightly inferior to 7 to 9 and 11 to 12.

On the other hand, when the cord of polyethylene-2,6-naphthalate fiber was not used as the organic fiber cord as in Comparative Examples 1 to 3, the balance between the maneuverability and the turning property was poor. Moreover, these values were at low levels.

[0042]

According to the present invention, it is possible to provide a high-performance pneumatic tire for a two-wheeled vehicle which is excellent in maneuverability and turning performance and has a good balance between them.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) D02G 3/48 D02G 3/48

Claims (6)

[Claims] 1. A carcass cord comprising at least a spiral belt layer formed of a cord disposed inside a tread and in a tire circumferential direction, and a carcass cord combined with the spiral belt layer. ,
A pneumatic tire for a motorcycle, which is substantially formed of polyethylene-2,6-naphthalate. 2. The pneumatic tire for a motorcycle according to claim 1, wherein the carcass cord has a tensile modulus at 50 ± 5 ° C. of 6660 to 11770 MPa. 3. A carcass cord comprising polyethylene-2,
The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the pneumatic tire is formed of a twisted yarn of a raw yarn substantially formed of 6-naphthalate. 4. The pneumatic tire for a motorcycle according to claim 3, wherein a twist coefficient (R) of the twisted yarn represented by the following formula is from 1440 to 2660. Twist coefficient (R) = N × √ (0.9D) where N is the number of twists (twice / 10c
m), and D represents the total display decitex of the carcass code. 5. The pneumatic tire for a motorcycle according to claim 1, wherein the total display decitex of the carcass cord is 2200 to 5010. 6. The rubber coated on the carcass cord,
The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein a tensile stress at 0% elongation is 0.98 to 1.96.