JP2023145319A - Motor cycle tire - Google Patents

Abstract

To provide a motor cycle tire capable of exhibiting excellent steering stability even while a steel cord is used as a belt layer material.SOLUTION: This motor cycle tire comprises a steel cord having a belt layer helically wound in a tire circumferential direction. The steel cord has an m×n structure in which n (2-6) strands twining m (1-3) steel filaments are twined in the same direction as that of the steel filaments. The diameter of each of the steel filaments is 0.15-0.25 mm. The temperature of a rubber composition constituting a tread is 70°C, initial strain is 5%, dynamic strain is ±1%, a frequency is 10 Hz, and a deformation mode: a complex elastic modulus E*(MPa) measured under an elongation condition is 5.0 MPa. A product (S×E*) of a total sectional area S (mm2) and the complex elastic modulus E*(MPa) of the steel filaments in the steel cord is 2.00 or smaller.SELECTED DRAWING: None

Description

The present invention relates to a motorcycle tire, and more particularly to a motorcycle tire in which a steel cord is used in the belt layer.

As the performance of motorcycles improves, there is an increasing demand for motorcycle tires (hereinafter also simply referred to as "tires") to improve performance such as handling stability. In order to meet such demands, in recent years, higher strength aramid cords have been used as belt layers in place of the conventionally used nylon 66 (registered trademark) cords.

However, aramid cord is very expensive, and during its production, chemicals such as concentrated sulfuric acid are used that have a negative impact on the environment. For this reason, together with the recent rise in environmental awareness, cheaper and more environmentally friendly materials are desired, and the use of steel cord is being considered as such a material.

In other words, steel cord is a material that is cheaper than aramid cord, has a relatively small impact on environmental pollution, and has a high modulus similar to aramid cord, so if it can be used as a belt layer material, preferable.

Therefore, various techniques have been proposed in which steel cord is used as the belt layer material (for example, Patent Documents 1 and 2).

Japanese Patent Application Publication No. 2014-172548 Patent No. 6863000

However, steel cords have higher bending rigidity and compression rigidity than aramid cords, and have the property of buckling when compressed forcibly. Among these, high bending rigidity may deform the ground contact shape of a motorcycle tire having a curved tread surface, leading to deterioration of handling stability. Furthermore, the high compression stiffness may lead to the occurrence of a buckling phenomenon in which a portion of the tire lifts off the ground contact surface and waves, particularly during high-speed turns, which may deteriorate steering stability. Therefore, there is room for improvement in improving steering stability during high-speed turns when steel cord is used as a belt layer material for motorcycle tires.

The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a motorcycle tire that uses steel cord as a belt layer material and yet provides excellent handling stability during high-speed turns. .

The inventors of the present invention have conducted intensive studies to solve the above problems, and have found that the above problems can be solved by the invention described below.

The present invention
A motorcycle tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer disposed outside the carcass in the tire radial direction and inside the tread portion,
The belt layer is a steel belt layer having a steel cord,
The steel cord is a steel cord having an m×n configuration in which n strands of m steel filaments are twisted together in the same direction as the steel filaments, and m is 1 or more and 3 or less, The n is 2 or more and 6 or less,
The diameter of the steel filament is 0.15 mm or more and 0.25 mm or less,
The rubber composition constituting the tread portion has a complex modulus of elasticity E ^* (MPa ) is a rubber composition with a pressure of 5.0 MPa or more,
The product (S×E ^* ) of the total cross-sectional area S (mm ² ) of the steel filament in the cross section of the steel cord and the complex modulus of elasticity E ^* (MPa) is 2.00 or less. This is a motorcycle tire.

According to the present invention, it is possible to provide a motorcycle tire that provides excellent handling stability even though steel cord is used as the belt layer material.

1 is a partial schematic sectional view of a motorcycle tire according to the present invention. FIG. 1 is a schematic perspective view showing an example of the structure of a belt layer in the present invention. 1 is a schematic cross-sectional view showing an example of the structure of a steel cord in the present invention. It is a figure explaining the sample for measurement of the compressive rigidity value of a steel cord, and the sample for correction. FIG. 2 is a schematic side view illustrating a method for measuring the compressive stiffness value of a steel cord. It is a figure explaining the calculation method of the compression rigidity value of a steel cord. It is a figure explaining the determination method of the presence or absence of a buckling point of a steel cord. It is a figure explaining the measuring method of the bending rigidity value of a steel cord.

[1] Tire according to the present invention First, a motorcycle tire according to the present invention (hereinafter also simply referred to as "tire") will be described.

1. Overall Configuration FIG. 1 is a partial schematic sectional view of a tire according to the present invention. In FIG. 1, 1 is a tire, 2 is a tread portion, 3 is a sidewall portion, 4 is a bead portion, 5 is a bead core, 6 is a carcass, 7 is a belt layer, and 8 is bead apex rubber.

As shown in FIG. 1, a tire 1 according to the present invention includes a carcass 6 extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, and a carcass 6 that is outside the carcass 6 in the tire radial direction and inside the tread portion 2. A belt layer 7 disposed on the belt layer 7 is provided. In addition, in FIG. 1, 1/4 of the tire radial cross section is shown, and it is symmetrical with respect to the equatorial plane and the tire rotation axis.

2. Component (1) Belt Layer At least one (two in FIG. 1) belt layer 7 is arranged.

FIG. 2 is a schematic perspective view showing an example (in the case of one belt layer) of the structure of the belt layer in the present invention, where 10 is a steel cord and G is a covering rubber. As shown in FIG. 2, the belt layer 7 is formed by covering a cord array in which steel cords 10 are aligned with a covering rubber G.

The number of steel cords 10 arranged in the cord array body is determined appropriately taking into consideration the rigidity and thickness of the steel cords used, but the number (ends) per 50 mm width is usually 30. It is preferable that the number is at least 50 books and no more than 50 books.

In the present invention, a steel belt layer having a steel cord is used as the belt layer, and the steel cord is made by twisting n strands each having m steel filaments twisted together in the same direction as the steel filaments. It has an m×n configuration, where m is 1 or more and 3 or less, and n is 2 or more and 6 or less. Note that the diameter of the steel filament is 0.15 mm or more and 0.25 mm or less.

FIG. 3 is a schematic cross-sectional view showing an example of the structure of the steel cord in the present invention. In addition, in FIG. 3, a steel cord with a 3×3 configuration (m=3, n=3) is shown, and a strand 12 in which three steel filaments f are twisted together is a steel cord. 10 are formed.

In the present invention, the steel filament f is, for example, "SWRH72A" specified in JIS G3506-2017 (C: 0.69 to 0.75%, Mn: 0.30 to 0.60%, Si: 0. 15 to 0.35%, P: 0.030% or less, S: 0.030% or less).

(2) Tread Portion The tread portion 2 has a tread surface that curves and extends in a convex arc shape from the tire equator C toward the tread end Te. The tread width Tw has a maximum width between Te on both sides of the tire equator C. This makes it possible to turn with a large bank angle. Note that, as described later, the tread portion 2 may be divided into an outer region OUT and an inner region IN in the tire width direction, but the dividing position at that time is determined by the friction force generation function of the tread portion 2. It may be set as appropriate, taking into consideration the balance between the function and the reaction force generation function.

In the present invention, the rubber composition (tread rubber composition) constituting the tread portion is prepared under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: elongation. A rubber composition having a complex modulus of elasticity E ^* (MPa) of 5.0 MPa or more is used.

The complex modulus of elasticity E ^* can be measured, for example, using a viscoelasticity measuring device such as "Iprexor (registered trademark)" manufactured by GABO.

Further, the product (S× ^E *) of the total cross-sectional area S (mm ² ) of the steel filaments in the cross-section of the steel cord and the complex modulus of elasticity E ^* (MPa) of the tread rubber composition is 2.00 or less. It is.

Note that the tread portion is not limited to being formed of a single rubber layer, and may be formed of multiple layers of rubber composition such as a base layer and a cap layer. In this case, the above-mentioned complex elastic modulus E ^* refers to the complex modulus of elasticity E ^* in the cap layer, which is the outermost layer.

Further, the complex modulus E ^* (MPa) of the tread rubber composition can be adjusted as appropriate by using the compounding materials described below. For example, by increasing the content of fillers such as silica and carbon black, decreasing the content of plasticizer components such as oil and resin, increasing the content ^of sulfur and accelerators, etc. ) can be increased. Conversely, by reducing the content of fillers such as silica and carbon black, increasing the content of plasticizer components such as oil and resin, and reducing the content of sulfur and accelerators, the complex modulus E ^* (MPa ) can be lowered.

(3) Others The carcass 6 has ply folded parts 6b that are folded back from the inside to the outside in the axial direction of the tire around the bead cores 5 at both ends of a toroidal ply body part 6a spanning between the bead cores 5. , at least one (one in FIG. 1) is arranged. A bead apex rubber 8 is disposed between the ply main body portion 6a and the ply folded portion 6b, and extends from the bead core 5 toward the outside in the tire radial direction in a tapered shape. Further, a belt reinforcing layer 9 is wound in the tire circumferential direction on the outside of the belt layer in the tire radial direction.

In one form of the invention, the tire carcass 6 and belt reinforcing layer 9 include organic fiber cords formed from organic fibers. Examples of organic fibers include polyester, polyamide, and cellulose. These may be synthetic fibers or biomass-derived fibers. In addition, these fibers may be formed from a single component of synthetic fibers, biomass fibers, recycled/regenerated fibers, and can be used as hybrid cords made by twisting these fibers together, cords using multifilaments made by combining filaments of each type, etc. It may be any code having a chemical structure in which the components of the code are chemically bonded.

Examples of the polyester cord include polyethylene terephthalate (PET) cord, polyethylene naphthalate (PEN) cord, polyethylene furanoate (PEF), and the like. PEF may be used because it has excellent air permeation resistance compared to other polyester cords and can easily maintain the air pressure inside the tire. Further, a part of the polyester cord may be a hybrid cord with a cord made of other organic fibers instead of a cord made of other organic fibers such as polyamide fibers.

When the polyester cord is a biomass-derived polyester cord, a biomass PET cord using biomass-derived terephthalic acid or ethylene glycol, a biomass PEF using biomass-derived furandicarboxylic acid, etc. can be suitably used.

The biomass polyester cord is obtained from biomass terephthalic acid, biomass ethylene glycol, etc. converted from bioethanol, furfurals, carenes, cymenes, terpenes, etc., converted from compounds derived from various animals and plants, or directly fermented from microorganisms, etc. Is possible.

Examples of the polyamide cord include aliphatic polyamide, semi-aromatic polyamide, and fully aromatic polyamide.

Aliphatic polyamide is a polyamide with a skeleton in which straight carbon chains are connected by amide bonds, and includes nylon 4 (PA4), nylon 410 (PA410), nylon 6 (PA6), nylon 66 (PA66), and nylon 610 (PA610). ), nylon 1010 (PA1010), nylon 1012 (PA1012), nylon 11 (PA11), and the like. Among them, nylon 4, nylon 410, nylon 610, nylon 10, nylon 1010, nylon 11, etc. are cited as materials that are partially or completely derived from biomass and are easily obtained.

Nylon 6 and nylon 66 include those obtained by ring-opening polymerization of caprolactam derived from conventional chemical synthesis, those obtained by condensation polymerization of hexamethylene diamine and adipic acid, and biocaprolactam or nylon 66 made from bio-derived cyclohexane as a starting material. Nylon 6 or nylon 66 made by producing bioadipic acid or biohexamethylene diamine may also be used. Further, the above-mentioned biomaterial may be obtained from sugar such as glucose. These nylon 6 and nylon 66 are considered to have the same strength as those conventionally used.

A representative example of nylon 4 is one made from 2-pyrrolidone obtained by converting glutamic acid derived from biofermentation into γ-aminobutyric acid, but is not limited thereto. Nylon 4 has good thermal and mechanical stability and is easy to design a polymer structure, so it can be suitably used because it contributes to improving tire performance and strength. .

Nylon 410, nylon 610, nylon 1010, nylon 1012, nylon 11, and the like can be obtained using ricinoleic acid obtained from castor oil as a raw material. Specifically, nylon 410, nylon 610, and nylon 1010 can be obtained by condensation polymerization of sebacic acid, dodecanedioic acid obtained from castor oil, and any diamine compound, and 11-aminoundecanoic acid obtained from castor oil. Nylon 11 can be obtained by condensation polymerization.

Semi-aromatic polyamide is a polyamide having an aromatic ring structure as part of its molecular chain, and includes, for example, nylon 4T (PA4T), nylon 6T (PA6T), and nylon 10T (PA10T).

Nylon 4T, nylon 6T, and nylon 10T can be obtained by performing condensation polymerization with a diamine compound having an arbitrary number of carbon atoms using terephthalic acid as a dicarboxylic acid. At that time, it is also possible to obtain these nylon materials using the aforementioned biomass-derived terephthalic acid. Since these have a rigid cyclic structure within their molecular chains, they are excellent in terms of heat resistance.

In addition, as the above-mentioned aliphatic polyamide and semi-aromatic polyamide, polyamide 5X (X is the number of carbon atoms derived from dicarboxylic acid, and T represents an integer or terephthalic acid) is produced by polymerizing lysine-derived 1,5-pentanediamine with dicarboxylic acids. ) can be mentioned.

The wholly aromatic polyamide is a polyamide having a skeleton in which aromatic rings are connected by amide bonds, and includes polyparaphenylene terephthalamide and the like. Like the aliphatic polyamide and semi-aromatic polyamide described above, the wholly aromatic polyamide may also be obtained by combining biomass-derived terephthalic acid and phenylene diamine.

Examples of cellulose fibers include rayon, polynosic, cupro, acetate, lyocell, and modal, which are manufactured from plant materials such as wood pulp. These cellulose fibers are preferable because they are not only carbon neutral raw materials, but also have excellent environmental performance such as being biodegradable and producing no harmful gases even when incinerated after use. Among the above, rayon, polynosic, and lyocell are particularly preferred from the standpoint of process efficiency, environmental friendliness, and mechanical strength.

Moreover, the above-mentioned cord may be a recycled cord obtained by re-spinning the cord recovered and purified from used items such as beverage bottles and clothing, regardless of whether it is synthetic or derived from biomass.

The cords described above may be formed by twisting one or more filaments together. For example, after combining two 1100 decitex multifilaments (in other words, 1100/2 decitex) and applying a first twist of 48 times/10 cm, combine the two first twisted cords and twist the first twist in the opposite direction or the same way as the first twist. Combine two 1670 decitex multifilaments with the same number of twists in the same direction (in other words, 1670/2 decitex), twist them 40 times/10cm, and then combine these two twisted cords. In addition, it is possible to use ply-twisted materials.

The tire according to the present invention has the above-described structure, thereby providing a motorcycle tire that can obtain excellent handling stability even though steel cord is used as the belt layer material, as described later. I can do it.

3. Mechanism of effect expression in the tire according to the present invention The mechanism of effect expression in the tire according to the present invention is presumed as follows.

(1) Structure of steel cord As mentioned above, when steel cord is used as a belt layer material, there is a concern that its high compression rigidity and high bending rigidity will lead to deterioration of steering stability during high-speed turns. be done.

Therefore, the present inventor first conducted intensive studies on the structure of a steel cord having a low compressive stiffness value and an appropriate bending stiffness value.

As a result, m steel filaments with a diameter of 0.15 mm or more and 0.25 mm or less are twisted together to form a strand, and then this strand is twisted into 2 or more and 6 or less steel filaments. When n pieces of steel cord are twisted together in the same direction as the steel filaments to form a steel cord with an m×n configuration, the compressive stiffness value is low and the bending stiffness value is appropriate, so it is preferable as a belt layer material. I found out that it can be adopted.

That is, first, when the number m of steel filaments forming a strand exceeds 3, a thick strand is formed even if the diameter of the steel filament is small, leading to an increase in the compressive rigidity value of the steel cord. Furthermore, when the steel cord and the rubber composition are combined, the degree of penetration of the rubber into the gaps within the strands decreases rapidly, allowing moisture to penetrate into the strands, causing rust and deterioration of adhesive performance. I'll be there. On the other hand, if the number m of steel filaments forming the strand is 3 or less, a thick strand will not be formed and the above-mentioned problems will not occur.

Next, when n exceeds 6 in a steel cord with an m×n configuration, the actual cross-sectional structure of the steel cord becomes a layered structure such as an m×1+m×(n-1) configuration, and an m×1 configuration. Since the strands become the core strands, the compression rigidity increases. On the other hand, if n is 2 or more and 6 or less, no core strand will be formed, so such problems will not occur.

Next, if the diameter of the steel filament is less than 0.15 mm, the rigidity of the steel filament will be low, so there is a concern that the reaction force generated during turning will be reduced. On the other hand, if it exceeds 0.25 mm, the compression rigidity will increase. On the other hand, if the diameter of the steel filament is 0.15 mm or more and 0.25 mm, such problems will not occur.

As described above, in the present invention, by employing steel cord with a low compression stiffness value as the belt layer material, it is possible to appropriately prevent deformation of the tread surface during tire running, especially deformation at high speeds and high loads. can be followed. As a result, it is thought that the occurrence of the buckling phenomenon described above is prevented, stable handling is obtained even during high-speed turns, and handling stability is improved.

(2) Complex modulus of elasticity of the rubber composition constituting the tread portion The present inventor believes that in order to stably exhibit excellent handling stability, it is sufficient to simply employ the steel cord described above as the belt layer material. However, we believe that it is necessary to consider the physical properties of the tread rubber that comes into direct contact with the road surface, and conducted further experiments and studies on the rubber composition that makes up the tread (tread rubber composition).

As a result, the complex modulus of elasticity E ^* (MPa) of the tread rubber composition measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: extension. When a rubber composition with a pressure of 5.0 MPa or more is used, the belt layer deforms flexibly when the tire is running, making it easier to obtain a large reaction force, and since sufficient force is applied from the tread rubber to the road surface, it is possible to drive at high speeds. It was found that the steering stability during turns was further improved. In addition, it is more preferable that it is 6.5 MPa or more, and as an upper limit, although it is not specifically limited, it is preferable that it is 20 MPa or less, and it is more preferable that it is 10.0 MPa or less.

At this time, in order to increase the reaction force generated in the entire tread part and improve steering stability during high-speed turns, it is necessary to increase the area occupied by the steel filaments in the belt layer, that is, It is necessary to control the product (S×E ^* ) of the total cross-sectional area S (mm ² ) of the steel filaments in the cross section of the cord and the complex modulus of elasticity E ^* (MPa) of the tread rubber composition to an appropriate range. After understanding this, we conducted further experiments and studies. As a result, it was found that (S×E ^* ) should be 2.00 or less. In addition, it is more preferable that it is less than 1.70, and the lower limit is not particularly limited, but it is preferably 0.60 or more.

As a result, the compressive rigidity of the belt layer is reduced, making it easier to follow the road surface, and also making it easier to generate reaction force in the tread and belt layer during turns, improving steering stability during high-speed turns. It is thought that this will become possible.

[2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can obtain even greater effects by adopting the following embodiments.

1. Compression rigidity value of steel cord As mentioned above, in the present invention, the compression rigidity value of the steel cord is made low, but if it is 65 N/mm or less, the flexibility will increase and the tread portion will be less susceptible to deformation. This is preferable because it allows more sufficient tracking. Note that the lower limit is not particularly limited, but is preferably 40 N/mm or more.

Note that the compressive stiffness value of the steel cord described above can be measured according to the following procedure. First, a vulcanized rubber molded body (vulcanization conditions: 165°C x 18 minutes) in which one steel cord with a length of 25 mm was embedded in the center of a cylindrical rubber cylinder with a diameter of 25 mm and a height of 25 mm was used as a measurement sample with one specification. Create three for each. Next, one correction sample is created in the same manner except that the steel cord is not embedded.

Next, each obtained sample is compressed in the height direction at a speed of 2.0 mm/min using a tensile tester, and the compression load and amount of compression are measured. Thereafter, from the measurement data obtained from the measurement samples, the maximum value of the slope is calculated from a graph with the amount of compression on the X axis and the compression load on the Y axis, and a simple average of the three measurement samples is calculated. Next, for the correction sample, the maximum value of the slope of the compressive load with respect to the amount of compression is calculated in the same way, and by subtracting it from the slope of the measurement sample, the compressive rigidity of the steel cord is calculated.

The specific measurement of this compression stiffness value will be explained using FIGS. 4 to 6. FIG. 4 is a diagram illustrating a measurement sample and a correction sample. In FIG. 4, K0 is a correction sample in which no steel cord is embedded. K1 to K3 are three measurement samples in which steel cords are embedded.

FIG. 5 is a schematic side view illustrating a method for measuring the compression stiffness value of a steel cord. It is compressed at the above-mentioned speed, and the SS curve is plotted with the horizontal axis as the compression distance (compression amount) and the vertical axis as the compression load. obtain.

FIG. 6 is a diagram illustrating a method for calculating the compression stiffness value, and shows SS curves obtained from each sample of K0 to K3. From Figure 6, the slope of the SS curve of K0 is constant, while the slope of the SS curves of K1 to K3 becomes larger due to force being applied to the steel cord from the middle, and after the steel cord buckles, You can see that it has returned to its original slope. This change in slope is caused by the compressive stiffness of the steel cord, so the compressive stiffness of the steel cord can be found by subtracting the maximum slope at K0 from the maximum slope at K1 to K3. , K1 to K3 is the compressive stiffness of the target steel cord (1133 N/mm in FIG. 6).

2. Buckling Point of Steel Cord In the present invention, it is preferable that the steel cord has no buckling point. This is because there is no buckling point, so even if the steel cord is subjected to large stress during high-speed turning, the steel cord will not break. Further, it is possible to suppress the progress of strength reduction due to compression fatigue.

Generally speaking, the buckling point of the steel cord mentioned above is determined by the value of the slope from increasing to decreasing in the graph shown in Figure 7, which shows the relationship between the slope (N/mm) and the amount of compression (mm) during compression stiffness measurement. It can be determined from the bending point at which the bending point changes to , that is, the point that indicates the compressive stiffness, but if the difference between the maximum slope and the minimum slope is small, it cannot be clearly determined as the bending point. . Therefore, in the present invention, the difference (CSmax-CSmin) between the maximum slope value (CSmax) and the subsequent minimum slope value (CSmin: the slope near the right end in FIG. 7) is calculated, and if this difference is 200 N/mm or less, is determined to be "no buckling point", and when it exceeds 200 N/mm, it is determined to be "buckling point present".

3. Bending rigidity value of steel cord As mentioned above, in the present invention, the bending rigidity value of the steel cord is made low, but if the bending rigidity value is 2.5 × 10 ^-3 N m or less, the belt layer will not bend over the curved surface of the tire. This is preferable because it can be easily followed by the tread and the ground contact shape can be finished in the desired shape. It is more preferably 2.0×10 ⁻³ N·m or less, and even more preferably 1.5×10 ⁻³ N·m or less. On the other hand, the lower limit is not particularly limited, but is preferably 0.5×10 ⁻³ N·m or more.

The bending stiffness value of the steel cord described above can be measured, for example, using a stiffness tester (for example, Model 150-D) manufactured by TABER (USA) according to the following procedure. First, both ends of a steel cord having a length of 145 mm were attached to the clamps of a rigidity testing machine, and as shown in FIG. 8, bending angles of +15 degrees and -15 degrees were given to the steel cord 10. Then, the average value of the bending moment at +15 degrees and the bending moment at -15 degrees is defined as the bending stiffness value (N·m).

In addition, if the steel ^cord and tread rubber are too hard, the stiffness of the tire will become strong and the ride comfort will worsen. Therefore, the product (FR ×E ^* ) is preferably 25×10 ⁻³ (MPa·N·m) or less. It is more preferably 15×10 ⁻³ (MPa·N·m) or less, and even more preferably 10×10 ⁻³ (MPa·N·m) or less. The lower limit is not particularly limited, but it is preferably 5×10 ⁻³ (MPa·N·m) or more, and more preferably 7×10 ⁻³ (MPa·N·m) or more.

4. Coating Rubber for Belt Layer The belt layer can be obtained by coating the above-mentioned steel cord with a rubber composition of a predetermined composition, but in the present invention, organic acid cobalt is blended in this rubber composition. is preferred. As a result, the adhesive strength to the steel cord is significantly improved, and good steel cord coverage can be ensured.

Specific examples of cobalt organic acids include cobalt stearate, cobalt boron neodecanoate, cobalt naphthenate, cobalt neodecanoate, etc. Cobalt stearate is preferable because it has a viscosity reducing effect, and after oxidative deterioration. Cobalt boron neodecanoate is preferred in that it has good elongation at break and good adhesion to steel cord after moist heat aging.

The content of the organic acid cobalt is preferably 0.05 parts by mass or more, and more preferably 0.08 parts by mass or more in terms of cobalt, based on 100 parts by weight of the rubber component. If it is less than 0.05 part by mass, there is a possibility that sufficient steel cord adhesion may not be ensured. On the other hand, it is preferably 0.20 parts by mass or less, more preferably 0.17 parts by mass or less. If it exceeds 0.20 parts by mass, the elongation at break after oxidative deterioration tends to decrease.

5. Multilayer Belt Layer In the present invention, the belt layer may be one layer, but is preferably multilayered with two or more layers. At this time, the average distance D (mm) between the steel cords in at least one set of belt layers adjacent to each other in the radial direction of the tire is preferably 0.6 mm or less, and preferably 0.5 mm or less. More preferably, it is 0.45 mm or less.

As a result, one set of belt layers cooperates with each other to appropriately restrain the tread portion and suppress the amount of deformation of the tread portion during rolling, further improving steering stability during high-speed running. You can improve your performance.

Note that the average distance D between the steel cord layers referred to here is the distance between the inner surface of the steel cord of the front belt layer and the outer surface of the steel cord of the inner belt layer on the equatorial plane of two overlapping belt layers. It is distance.

In the case of multi-layered belt layers, in at least one set of belt layers adjacent in the radial direction of the tire, the angle formed by the steel cords in each belt layer in the tread portion in the tire circumferential direction is The angle is preferably 65° or less, more preferably 60° or less, and even more preferably 58° or less.

By arranging belt layers that are inclined to each other at appropriate angles, a restraining effect can be obtained, and almost the entire width of the tread section can be firmly restrained, thereby suppressing the amount of deformation of the tread section during rolling. Therefore, it is possible to further improve steering stability during high-speed driving.

Note that the angle is the angle of the steel cord with respect to the circumferential direction of the tire when the tire is not filled with air, and can be confirmed by peeling off the tread portion of the tire from the outside in the radial direction.

In addition, when there are two belt layers, the ratio (L2 /L1) is preferably greater than 1.00. It is thought that by relatively increasing the length of the belt layer on the outside in the radial direction of the tire in the width direction of the tire, it is possible to make it easier to obtain a protection effect and also to make it easier to generate a larger reaction force in the tread portion. .

The ratio (L2/L1) of the tire width direction length L1 (mm) of the tire radially outer belt layer to the tire width direction length L1 (mm) of the tire radially inner belt layer is as described above. , is preferably over 1.00, more preferably over 1.05, even more preferably over 1.10. On the other hand, the upper limit is not particularly limited, but is preferably less than 1.30, more preferably less than 1.25, and even more preferably less than 1.20.

The length of the belt layer in the tire width direction here refers to the length of the circular arc drawn by the belt layer in the cross section in the tire width direction. It can be determined by measuring in the same condition.

In addition, when three or more belt layers are provided, it is preferable that the above-mentioned L2/L1 relationship is established between mutually adjacent belt layers, and the belt layers in the tire width direction gradually move from the outermost layer to the innermost layer. Preferably, the width is short.

6. Division of Tread Portion In the present invention, the tread portion is preferably divided in the width direction of the tire. That is, when the tire is traveling straight, the inner portion of the tread portion in the width direction mainly contacts the road surface with high ground pressure. On the other hand, when turning, the outer part of the tread in the width direction tends to become the contact surface due to the lateral force, and this tendency becomes more pronounced when driving at high speeds, and there is a risk of skidding due to centrifugal force.

For this reason, a strong reaction force is required in the inner part of the tread part, and a strong frictional force is required in the outer part, and the tread part is divided into an inner region and an outer region sandwiching it, depending on the required function. is preferred. In this case, both the inner region and the outer region satisfy the above-described complex modulus of elasticity E ^* (MPa) of 5.0 MPa or more and (S×E ^* ) of 2.00 or less. It is preferable that

At this time, as the rubber composition constituting the outer region of the tread portion, it is preferable to use a rubber composition containing 25% by mass or less of styrene in the rubber component and having a Tg of -18° C. or higher. In other words, by containing 25% by mass or less of styrene in the rubber component, the interaction and aggregation effect between styrene parts is weakened, allowing the polymer molecules to move flexibly and increasing the contact area between the road surface and the polymer. This improves grip performance during high-speed turns and improves steering stability. Since a certain amount of styrene is contained in the rubber component, the styrene parts in the polymer that move flexibly can easily generate heat due to mutual friction, which further promotes the movement of the polymer molecules and allows them to rotate at high speed. The inner grip performance is further improved, and better handling stability can be obtained. In addition, since a rubber composition with a high Tg of -18°C or higher easily generates heat, it is necessary to further promote the movement of polymer molecules, improve grip performance during high-speed turns, and obtain better steering stability. I can do it.

For the above reasons, even when the tread part is not divided, the rubber composition of the tread part is a rubber composition that contains 25% by mass or less of styrene in the rubber component and has a Tg of -18°C or higher. It is preferable.

The above-mentioned glass transition temperature (Tg) of the rubber composition can be determined from the tan δ temperature distribution curve measured using a viscoelasticity measuring device such as the "Iprexor (registered trademark)" series manufactured by GABO. . Specifically, the temperature corresponding to the largest tan δ value (tan δ peak temperature) in the obtained tan δ temperature distribution curve is defined as the glass transition temperature (Tg). The temperature is more preferably -16°C or higher, and even more preferably -15°C or higher. On the other hand, the upper limit is not particularly limited, but is preferably 0°C or lower, more preferably -8°C or lower, and even more preferably -10°C or lower.

In the present invention, it is preferable that the content ratio of carbon black in the outer region of the tread portion is higher than the content ratio of carbon black in the inner region of the tread portion.

By making the content ratio of carbon black in the outer region higher than the content ratio of carbon black in the inner region, when a load is applied to the outer region during high-speed turning, the temperature tends to rise due to friction between the carbon black and the polymer. Since the motion of the polymer can be further promoted, grip performance during high-speed turns can be improved, and steering stability can be improved.

On the other hand, in the inner region, since the amount of carbon black is small, heat generation is suppressed, and the rigidity of the inner region, which is likely to touch the ground at the beginning of a turn, is ensured, making it easier to apply a load to the outer region during turning. As a result, the temperature of the outer region increases more easily, the movement of the polymer is further promoted, the grip performance during high-speed turns is improved, and the steering stability can be improved.

Note that the specific difference between the content ratio of carbon black in the outer region and the content ratio of carbon black in the inner region is preferably 20% by mass or more, and more preferably 30% by mass or more. On the other hand, the upper limit is not particularly limited, but is preferably 40% by mass or less, more preferably 38% by mass or less.

7. Relationship between Tread Width and Belt Layer Width In the present invention, the ratio (Lm/Tw) of the maximum length Lm (mm) of the belt layer in the tire width direction to the tread width Tw (mm) is preferably 1.00 or more. By satisfying this relationship, that is, by making the maximum length Lm of the belt layer in the tire width direction equal to or greater than the tread width Tw, the belt layer forms an arc inside the tread portion in the tire radial direction, which further improves the protection effect. This makes it possible to easily maintain the shape of the tread surface in a round shape. Therefore, when the motorcycle turns, it becomes easier to tilt the vehicle body, and it is possible to improve the steering stability when traveling at high speed. Furthermore, even when the vehicle body is tilted, a belt layer exists on the radially inner side of the tire on the ground contact surface, making it easier to exert shearing force, making it easier to further improve handling stability. .

The maximum length Lm of the belt layer in the tire width direction referred to here refers to the maximum length of the belt layer in the tire width direction. That is, when there is one belt layer, the length of the belt layer in the tire width direction is Lm, and when there are two or more layers, the longest one among them is Lm.

Further, the tread width Tw refers to the length of the tread portion parallel to the tire width direction, and can be measured in a cross section cut out of the tire in the width direction, with the bead portion aligned with the regular rim width.

As mentioned above, the ratio (Lm/Tw) of the maximum length Lm (mm) of the belt layer in the tire width direction to the tread width Tw (mm) is preferably 1.00 or more, and 1.05 or more. More preferably, it is 1.10 or more. On the other hand, the upper limit is not particularly limited, but is preferably 1.50 or less, more preferably 1.45 or less, and even more preferably 1.40 or less.

[3] Embodiments Hereinafter, the present invention will be specifically described based on embodiments.

1. Tread Rubber Composition In this embodiment, the tread rubber composition can be obtained from various compounding materials such as rubber components, fillers, softeners, vulcanizing agents, and vulcanization accelerators described below.

(1) Compounded materials (a) Rubber component In this embodiment, the rubber component is not particularly limited, and diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR) are used. Rubbers (polymers) commonly used in tire manufacturing, such as butyl rubber, butyl rubber such as butyl rubber, thermoplastic elastomers such as styrene butadiene styrene block copolymer (SBS), and styrene butadiene copolymer (SB). However, as mentioned above, considering that the styrene content in the rubber component is preferably 25% by mass or less, any one of styrene polymers such as SBR, SBS, and SB may be used. and preferably SBR. These styrene polymers may be used in combination with other rubber components. For example, combinations of SBR and BR, and combinations of SBR, BR, and isoprene rubber are preferred.

(b) SBR
The weight average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The vinyl bond amount (1,2-bonded butadiene unit amount) of SBR is, for example, more than 5 mol% and less than 70 mol%. Note that the structural identification of SBR (measurement of styrene content and vinyl bond amount) can be performed using, for example, a JNM-ECA series device manufactured by JEOL Ltd.

The content of SBR in 100 parts by mass of the rubber component is preferably 55 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more.

The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used. SBR may be either non-denatured SBR or modified SBR. Further, hydrogenated SBR obtained by hydrogenating the butadiene part in SBR may be used, and hydrogenated SBR may be obtained by subsequently hydrogenating the BR part in SBR, and styrene, ethylene, and butadiene can be hydrogenated. A similar structure may be obtained by copolymerization. It may also be oil-extended SBR.

The modified SBR may be any SBR that has a functional group that interacts with a filler such as silica; for example, an end-modified SBR in which at least one end of the SBR is modified with a compound (modifier) having the above-mentioned functional group. SBR (terminally modified SBR having the above functional group at the end), main chain modified SBR having the above functional group in the main chain, main chain terminal modified SBR having the above functional group in the main chain and the end (e.g. The main chain end-modified SBR which has the above-mentioned functional group and has at least one end modified with the above-mentioned modifier, or is modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and has a hydroxyl group. and terminal-modified SBR into which an epoxy group has been introduced.

Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, and disulfide groups. group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. . Note that these functional groups may have a substituent.

Furthermore, as the modified SBR, for example, SBR modified with a compound (modifier) represented by the following formula can be used.

In the formula, R ¹ , R ² and R ³ are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH) or a derivative thereof. represent. R ⁴ and R ⁵ are the same or different and represent a hydrogen atom or an alkyl group. R ⁴ and R ⁵ may be combined to form a ring structure together with the nitrogen atom. n represents an integer.

The modified SBR modified with the compound (modifier) represented by the above formula includes a solution polymerized styrene butadiene rubber (S-SBR) whose polymerized end (active end) is modified with the compound represented by the above formula. SBR (modified SBR described in JP-A No. 2010-111753, etc.) can be used.

An alkoxy group is suitable as R ¹ , R ² and R ³ (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Furthermore, when R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltriethoxysilane, Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used alone or in combination of two or more.

Furthermore, as the modified SBR, modified SBR modified with the following compound (modifier) can also be used. Examples of modifiers include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; two or more of diglycidylated bisphenol A, etc. Polyglycidyl ethers of aromatic compounds having phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylene diamine , diglycidylamino compounds such as tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; bis-(1-methylpropyl)carbamic acid chloride; Amino group-containing acid chlorides such as 4-morpholine carbonyl chloride, 1-pyrrolidine carbonyl chloride, N,N-dimethylcarbamate acid chloride, N,N-diethylcarbamate acid chloride; 1,3-bis-(glycidyloxypropyl)-tetra Epoxy group-containing silane compounds such as methyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane; (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(methyldimethoxysilyl) propyl] sulfide, ( Sulfide groups such as (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide, etc. Containing silane compounds; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3- Alkoxysilanes such as aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; 4-N,N-dimethylaminobenzophenone, 4- N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'- (thio)benzophenone compounds having an amino group and/or substituted amino group such as bis(diphenylamino)benzophenone, N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N-dimethylamino Benzaldehyde compounds having an amino group and/or substituted amino group such as benzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2- N-substituted pyrrolidone such as pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-vinyl-2 - N-substituted piperidones such as piperidone, N-phenyl-2-piperidone; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurirolactam, N-vinyl-ω-lau N-substituted lactams such as lilolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethyl Acetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl- 2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino) -4-heptanone and the like can be mentioned. Note that modification with the above compound (modifier) can be carried out by a known method.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used. Note that SBR may be used alone or in combination of two or more types.

(b) BR
In this embodiment, the tread rubber composition may further contain BR, if necessary. In this case, the content of BR in 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 35 parts by mass or more. On the other hand, it is preferably 45 parts by mass or less, more preferably 40 parts by mass or less.

The weight average molecular weight of BR is, for example, more than 100,000 and less than 2,000,000. The amount of vinyl bonds in BR is, for example, more than 1% by mass and less than 30% by mass. The cis amount of BR is, for example, more than 1% by mass and less than 98% by mass. The amount of trans in BR is, for example, more than 1% by mass and less than 60% by mass.

The BR is not particularly limited, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. The BR may be either unmodified BR or modified BR, and examples of the modified BR include modified BR into which the above-mentioned functional groups have been introduced. These may be used alone or in combination of two or more. Note that the cis content can be measured by infrared absorption spectroscopy.

As the BR, for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

(iii) Isoprene-based rubber In the present embodiment, the tread rubber composition may further contain isoprene-based rubber, if necessary. In this case, the content of isoprene rubber in 100 parts by mass of the rubber component is preferably more than 20 parts by mass and less than 35 parts by mass.

Isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like.

As the NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example, one commonly used in the tire industry, such as IR2200, can be used. Modified NR includes deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc.; modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

(d) Other rubber components In addition, other rubber components may include rubbers (polymers) commonly used in tire manufacturing such as nitrile rubber (NBR).

(b) Compounding materials other than rubber components (a) Filler In the present embodiment, the rubber composition preferably contains a filler. Specific examples of fillers include carbon black, silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

(i) Carbon Black In this embodiment, the tread rubber composition preferably contains carbon black. The content of carbon black based on 100 parts by mass of the rubber component is preferably 65 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 75 parts by mass or more. On the other hand, the amount is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less.

Carbon black is not particularly limited, and includes furnace black (furnace carbon black) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF and ECF; acetylene black (acetylene carbon black) ; thermal blacks (thermal carbon blacks) such as FT and MT; channel blacks (channel carbon blacks) such as EPC, MPC and CC. These may be used alone or in combination of two or more.

The CTAB (Cetyl Tri-methyl Ammonium Bromide) specific surface area of carbon black is preferably 130 m ² /g or more, more preferably 160 m ² /g or more, and even more preferably 170 m ² /g or more. On the other hand, it is preferably 250 m ² /g or less, more preferably 200 m ² /g or less. Note that the CTAB specific surface area is a value measured in accordance with ASTM D3765-92.

Specific carbon blacks are not particularly limited, and include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. Commercially available products include, for example, products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kaya Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can be used. These may be used alone or in combination of two or more.

(ii-1) Silica In the present embodiment, the tread rubber composition preferably contains silica together with a silane coupling agent, if necessary.

The BET specific surface area of silica is preferably more than 140 m ² /g, more preferably more than 160 m ² /g, from the viewpoint of obtaining good durability performance. On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed running, it is preferably less than 250 m ² /g, more preferably less than 220 m ² /g. Note that the BET specific surface area described above is the value of N ₂ SA measured by the BET method according to ASTM D3037-93.

The content of silica per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 45 parts by mass or more, and even more preferably 60 parts by mass or more. On the other hand, the amount is preferably 170 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 80 parts by mass or less.

Examples of the silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and the like. Among these, wet process silica is preferred because it has a large number of silanol groups. Furthermore, silica made from hydrous glass or the like, silica made from biomass materials such as rice husks, etc. may be used.

As the silica, for example, products manufactured by Evonik Industries, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

In addition, in the case of silica-based tread rubber compositions containing a large amount of silica, conductive fillers such as graphite and fine metal fibers are added in order to efficiently release static electricity accumulated in the tire to the road surface. It is preferable to do so.

Further, a rubber layer for conducting electricity with a high content ratio of carbon black may be provided in the center of the tread portion. However, since such a current-carrying rubber layer has a small contribution to steering stability during high-speed turns, it is not necessary to satisfy the relationships in terms of physical properties and the like.

(ii-2) Silane coupling agent When using silica as a filling reinforcing agent, the rubber composition preferably contains a silane coupling agent together with the silica. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, Bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis( 3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) ) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide types such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto types such as NXT and NXT-Z manufactured by Momentive, vinyltriethoxysilane, and vinyl triethoxysilane. Vinyl types such as methoxysilane, amino types such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, and glycidoxy types such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. , 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and other nitro types, and 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, and other chloro types. These may be used alone or in combination of two or more.

As the silane coupling agent, for example, products manufactured by Evonik Industries, Momentive, Shin-Etsu Silicone, Tokyo Kasei Kogyo, Azumax, Dow Corning Toray, etc. can be used.

The content of the silane coupling agent is, for example, more than 3 parts by mass and less than 25 parts by mass based on 100 parts by mass of silica.

(iii) Other fillers In addition to the above-mentioned carbon black and silica, the rubber composition may optionally include fillers such as graphite, calcium carbonate, talc, alumina, etc., which are commonly used in the tire industry. It may further contain fillers such as clay, aluminum hydroxide, and mica. The content of these is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component.

(B) Plasticizer component The tread rubber composition may contain oil (including extender oil), liquid rubber, and resin as a plasticizer, as a component that softens the rubber. Note that the plasticizer component is a component that can be extracted from the vulcanized rubber with acetone. The total content of the plasticizer component is preferably, for example, 10 parts by mass or more, and more preferably 30 parts by mass or more, based on 100 parts by mass of the rubber component. On the other hand, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. Note that the oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

In addition, the amount of acetone extracted is determined according to JIS K 6229 by immersing a vulcanized rubber test piece in acetone for 72 hours to extract the soluble components, measuring the mass of each test piece before and after extraction, and using the following formula. be able to.
Acetone extraction amount (%) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction)
/(mass of rubber test piece before extraction)}×100

(i) Oil Oils include, for example, mineral oils (generally referred to as process oils), vegetable oils, or mixtures thereof. As the mineral oil (process oil), for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Furthermore, from the viewpoint of life cycle assessment, waste oil that has been used as a lubricating oil for rubber mixing mixers, automobile engines, etc., waste cooking oil, etc. may be used as appropriate.

Specific process oils (mineral oils) include, for example, Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., and Showa Shell Sekiyu Co., Ltd. ), Fuji Kosan Co., Ltd., etc. can be used.

(ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer that is in a liquid state at room temperature (25° C.), and is a rubber component that can be extracted from a vulcanized tire by acetone extraction. Examples of the liquid rubber include farnesene polymers, liquid diene polymers, and hydrogenated products thereof.

A farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a constituent unit based on farnesene. Farnesene includes α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1 , 6,10-dodecatriene).

The farnesene-based polymer may be a farnesene homopolymer (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

Examples of liquid diene-based polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), etc. It will be done.

The weight average molecular weight (Mw) of the liquid diene polymer measured by gel permeation chromatography (GPC) in terms of polystyrene is, for example, more than 1.0×10 ³ and less than 2.0×10 ⁵ . In this specification, the Mw of the liquid diene polymer is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

The content of liquid rubber (total content of liquid farnesene polymer, liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass based on 100 parts by mass of the rubber component.

As the liquid rubber, for example, products manufactured by Kuraray Co., Ltd., Clay Valley Co., Ltd., etc. can be used.

(iii) Resin component The resin component also functions as a tackifying component and may be solid or liquid at room temperature. Specific resin components include rosin resin, styrene resin, etc. , coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, acrylic resin, etc., and two or more types may be used in combination. The content of the resin component is preferably more than 2 parts by mass and less than 45 parts by mass, and more preferably less than 30 parts by mass, based on 100 parts by mass of the rubber component. Note that these resin components may be provided with a modifying group capable of reacting with silica or the like, if necessary.

Rosin resin is a resin whose main component is rosin acid obtained by processing pine resin. This rosin-based resin (rosin) can be classified according to the presence or absence of modification, and can be classified into unmodified rosin (unmodified rosin) and modified rosin (rosin derivative). Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. The modified rosin is a modified version of unmodified rosin, and includes rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, amide compounds of rosin, and amine salts of rosin.

The styrene resin is a polymer using a styrene monomer as a constituent monomer, and includes polymers polymerized with a styrene monomer as a main component (50% by mass or more). Specifically, styrenic monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, Homopolymers of o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), copolymers of two or more styrene monomers, and styrene monomers. and copolymers of other monomers that can be copolymerized therewith.

Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, acrylics, unsaturated carboxylic acids such as methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, chloroprene, and butadiene. Examples include dienes such as isoprene, olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride, or acid anhydrides thereof.

Among coumaron-based resins, coumaron indene resin is preferred. Coumarone indene resin is a resin containing coumaron and indene as monomer components constituting the skeleton (main chain) of the resin. In addition to coumaron and indene, monomer components contained in the skeleton include styrene, α-methylstyrene, methylindene, and vinyltoluene.

The content of the coumaron indene resin is, for example, more than 1.0 parts by mass and less than 50.0 parts by mass based on 100 parts by mass of the rubber component.

The hydroxyl value (OH value) of the coumaron indene resin is, for example, more than 15 mgKOH/g and less than 150 mgKOH/g. The OH value is the amount of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of resin, expressed in milligrams, and is determined by potentiometric titration method (JIS K 0070: (1992).

The softening point of the coumaron indene resin is, for example, higher than 30°C and lower than 160°C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point measuring device.

Examples of terpene resins include polyterpenes, terpene phenols, aromatic modified terpene resins, and the like. Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons and their oxygen-containing derivatives represented by the composition (C ₅ H ₈ ) _n , including monoterpenes (C ₁₀ H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), and diterpenes (C ₂₀ H _{32 )} . ) and other compounds whose basic skeletons are terpenes, such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, and terpinolene. , 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, and the like.

Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene/limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogen obtained by hydrogenating the terpene resin. Also included are added terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Examples include resin. Note that examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol, and the like. Examples of aromatic modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the resins. The aromatic compound is not particularly limited as long as it has an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Naphthol compounds such as unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumaron, indene, and the like.

"C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of the C5 fraction include petroleum fractions having 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, and isoprene. As the C5 petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

"C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified resin. Examples of the C9 fraction include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, for example, coumaron indene resin, coumaron resin, indene resin, and aromatic vinyl resin are preferably used. As the aromatic vinyl resin, α-methylstyrene, a styrene homopolymer, or a copolymer of α-methylstyrene and styrene is preferred because it is economical, easy to process, and has excellent heat generation properties. , a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl resin, for example, those commercially available from Clayton Co., Eastman Chemical Co., etc. can be used.

"C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of the C5 fraction and C9 fraction include the petroleum fractions described above. As the C5C9 resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

Although the acrylic resin is not particularly limited, for example, a solvent-free acrylic resin can be used.

Solvent-free acrylic resins are produced using a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (U.S. Patent No. 4,414,370), which uses as little as possible the use of auxiliary materials such as polymerization initiators, chain transfer agents, and organic solvents. specification, JP-A-59-6207, JP-A-5-58005, JP-A-1-313522, US Patent No. 5,010,166, Toagosei Research Annual Report TREND 2000 No. 3 p42 Examples include (meth)acrylic resins (polymers) synthesized by the method described in -45, etc. Note that in the present invention, (meth)acrylic means methacryl and acrylic.

Examples of monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives. Examples include (meth)acrylic acid derivatives such as.

In addition, as monomer components constituting the above acrylic resin, in addition to (meth)acrylic acid and (meth)acrylic acid derivatives, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc. aromatic vinyl may be used.

The acrylic resin may be a resin composed only of a (meth)acrylic component, or a resin containing components other than the (meth)acrylic component. Further, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

Examples of resin components include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nichiro Kagaku Co., Ltd. ) Products from Nippon Shokubai, ENEOS Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

(c) Stearic acid In this embodiment, the tread rubber composition preferably contains stearic acid. The content of stearic acid is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass based on 100 parts by mass of the rubber component. As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

(d) Anti-aging agent In this embodiment, the tread rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component.

Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; -isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, etc. p-phenylenediamine-based anti-aging agents; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methylphenol; Monophenolic anti-aging agents such as styrenated phenol; bis-, tris-, and polyphenol-based aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Examples include inhibitors. These may be used alone or in combination of two or more.

As the anti-aging agent, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis Co., Ltd., etc. can be used.

(e) Wax In the present invention, the rubber composition preferably contains wax. The content of wax is, for example, 0.5 to 20 parts by weight, preferably 1.0 to 15 parts by weight, and more preferably 1.5 to 10 parts by weight, based on 100 parts by weight of the rubber component.

The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable waxes and animal waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more.

As the wax, for example, products manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used.

(f) Zinc oxide The tread rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 10 parts by mass based on 100 parts by mass of the rubber component. As zinc oxide, conventionally known ones can be used, such as products from Mitsui Kinzoku Kogyo Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

(g) Crosslinking agent and vulcanization accelerator The tread rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass based on 100 parts by mass of the rubber component.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products manufactured by Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Karidome Kogyo Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. .

Examples of cross-linking agents other than sulfur include sulfur atoms such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd. and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess. and organic peroxides such as dicumyl peroxide.

Preferably, the tread rubber composition includes a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass based on 100 parts by mass of the rubber component.

Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- Sulfenamide vulcanization accelerators such as 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide; diphenylguanidine; Examples include guanidine-based vulcanization accelerators such as di-ortho-tolyl guanidine and ortho-tolyl biguanidine. These may be used alone or in combination of two or more.

(h) Others In addition to the above-mentioned components, the tread rubber composition contains additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, reversion (vulcanized If necessary, an anti-reversion agent or the like may be further added. The content of these additives is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component.

(2) Preparation of tread rubber composition The tread rubber composition is prepared by adjusting the above-mentioned various compounding materials as appropriate and using a general method, for example, a base kneading step of kneading the rubber component and filler such as carbon black. , is produced by a manufacturing method including a final kneading step of kneading the kneaded material obtained in the base kneading step and a crosslinking agent.

Kneading can be performed using a known (closed type) kneader such as a Banbury mixer, kneader, or open roll.

The kneading temperature in the base kneading step is, for example, more than 50° C. and less than 200° C., and the kneading time is, for example, more than 30 seconds and less than 30 minutes. In the base kneading process, in addition to the above ingredients, compounding agents conventionally used in the rubber industry, such as softeners such as oil, zinc oxide, anti-aging agents, wax, and vulcanization accelerators, are added as necessary. , may be kneaded.

In the final kneading step, the kneaded material obtained in the base kneading step and a crosslinking agent are kneaded. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80° C., and the kneading time is, for example, higher than 1 minute and shorter than 15 minutes. In the finishing kneading step, in addition to the above-mentioned components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

2. Belt Layer (1) Coating Rubber Composition In this embodiment, the coating rubber composition on which the steel cord is coated can basically be obtained from the same compounding materials as the tread rubber composition described above.

(a) Rubber component In the coating rubber composition, the rubber components include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and nitrile rubber (NBR), and butyl rubbers such as butyl rubber. Rubbers (polymers) commonly used in tire manufacturing, such as rubber, can be used, but among these, isoprene-based rubbers are preferred, as the cis structure of polyisoprene is close to 100%, and the tensile strength is higher than that of other rubbers. It is preferable to use NR because it is superior to the rubber component of NR. Note that SBR and BR may be used together if necessary.

(a) Isoprene rubber In the coating rubber composition, the content of isoprene rubber in 100 parts by mass of the rubber component is preferably 60 parts by mass or more, more preferably 80 parts by mass or more, and 90 parts by mass. It is more preferable that it is above.

(b) SBR
In the coating rubber composition, 5 parts by mass or more and 25 parts by mass or less of SBR may be used in the rubber component together with NR, if necessary.

(c) BR
In the coating rubber composition, 5 parts by mass or more and 25 parts by mass or less of BR may be used in combination with the above-described NR and SBR in the rubber component, if necessary.

(d) Other rubber components Further, as other rubber components, rubbers (polymers) commonly used in tire manufacturing such as nitrile rubber (NBR) may be included as needed.

(b) Compounding materials other than the rubber component (a) Filler (i) Carbon black In the coated rubber composition, the content of carbon black is, for example, 10 parts by mass or more, 100 parts by mass, based on 100 parts by mass of the rubber component. The amount is preferably 40 parts by mass or more and 70 parts by mass or less, and even more preferably 50 parts by mass or more and 60 parts by mass or less.

(ii) Silica It is preferable that the coated rubber composition further contains silica, if necessary, and a silane coupling agent may be used in combination. The content of silica relative to 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more when not used in combination with a silane coupling agent. On the other hand, it is preferably 25 parts by mass or less, more preferably 15 parts by mass or less. Furthermore, when used in combination with a silane coupling agent, the amount is preferably 25 parts by mass or more. On the other hand, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

(iii) Silane coupling agent In the coated rubber composition, the content of the silane coupling agent is, for example, more than 3 parts by mass and less than 15 parts by mass, based on 100 parts by mass of silica.

(iv) Other fillers The coated rubber composition may further contain fillers such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, and the like. The content of these is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component.

(b) Curable resin component The coating rubber composition preferably contains a curable resin component such as a modified resorcinol resin or a modified phenol resin. As a result, the adhesiveness with the steel cord can be improved without greatly deteriorating the heat generation property and the elongation at break, and it is possible to easily generate a large reaction force with the rubber and steel cord.

Specific examples of modified resorcinol resins include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd., and examples of modified phenol resins include PR12686 (cashew oil) manufactured by Sumitomo Bakelite Co., Ltd. Examples include modified phenolic resins).

The content of the curable resin component is preferably 1 part by mass or more, and 2 parts by mass, for example, from the viewpoint of sufficiently improving the complex modulus of elasticity and obtaining a large reaction force during deformation, based on 100 parts by mass of the rubber component. The above is more preferable. On the other hand, from the viewpoint of maintaining breaking strength, the content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

When using a modified resorcinol resin, it is preferable to also contain a methylene donor as a curing agent. Examples of the methylene donor include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), hexamethylolmelamine pentamethyl ether (HMMPME), etc. It is preferably contained in an amount of 5 parts by mass or more, and about 15 parts by mass. If it is too small, a sufficient complex modulus may not be obtained. On the other hand, if the amount is too large, the viscosity of the rubber may increase and processability may deteriorate.

As a specific methylene donor, for example, Sumikanol 507 manufactured by Taoka Chemical Industry Co., Ltd. can be used.

(c) Resin component In the coating rubber composition, from the viewpoint of processability (imparting tackiness), it is preferable to contain a resin component as necessary. The content of the resin component is preferably more than 2 parts by mass and less than 45 parts by mass, and more preferably less than 30 parts by mass, based on 100 parts by mass of the rubber component.

(d) Organic acid cobalt The coating rubber composition preferably contains organic acid cobalt. Since cobalt organic acid plays the role of crosslinking the cord and the rubber, by blending this component, it is possible to improve the adhesion between the cord and the rubber.

Examples of the organic acid cobalt include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, and cobalt boron-3 neodecanoate.

The content of the organic acid cobalt is preferably 500 ppm or more, more preferably 700 ppm or more, and even more preferably 900 ppm or more as the cobalt concentration in the coating rubber. On the other hand, it is preferably 1500 ppm or less, more preferably 1300 ppm or less. If it is too small, there is a risk that sufficient adhesion between the plating layer of the steel cord and the rubber may not be ensured. On the other hand, if the amount is too large, the oxidative deterioration of the rubber will become significant and there is a risk that the rupture properties will deteriorate.

(e) Reversion (reversion) inhibitor It is preferable that the coating rubber composition contains a reversion (reversion) inhibitor, if necessary. This suppresses reversion and improves durability. The content of the reversion inhibitor is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.2 parts by mass or more and 2.5 parts by mass or less, based on 100 parts by mass of the rubber component. , more preferably 0.3 parts by mass or more and 2 parts by mass or less. Note that, as a specific reversion inhibitor, Parkalink 900 (1,3-bis(citraconimidomethyl)benzene) manufactured by Flexis Co., Ltd. can be used, for example.

(f) Anti-aging agent In the coated rubber composition, the content of the anti-aging agent is, for example, more than 1 part by mass and less than 10 parts by mass, based on 100 parts by mass of the rubber component.

(g) Stearic acid In the coated rubber composition, the content of stearic acid is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass, based on 100 parts by mass of the rubber component.

(H) Zinc oxide In the coated rubber composition, the content of zinc oxide is, for example, more than 0.5 parts by mass and less than 15 parts by mass, based on 100 parts by mass of the rubber component.

(li) Crosslinking agent and vulcanization accelerator In the coated rubber composition, the content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass, based on 100 parts by mass of the rubber component.

In the coated rubber composition, the content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass, based on 100 parts by mass of the rubber component.

(v) Others In addition to the above-mentioned components, the coating rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, etc. Good too. The content of these additives is, for example, more than 0.1 part by mass and less than 200 parts by mass based on 100 parts by mass of the rubber component.

(2) Production of belt layer (a) Production of coated rubber composition The coated rubber composition can be produced through a base kneading process and a finishing kneading process in the same manner as in the production of the tread rubber composition described above.

(b) Manufacture of belt layer A belt layer is manufactured by coating and molding the obtained coated rubber composition onto both sides of steel cords arranged in predetermined ends using a calendar roll or the like.

3. Manufacture of Tire Members such as the belt layer and tread portion are molded using known methods. Then, an unvulcanized tire can be produced by molding the molded belt layer and tread portion together with other tire members on a tire molding machine using a conventional method.

Specifically, an inner liner, a carcass, a belt layer, etc., which are members for ensuring airtightness of the tire, are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and the tire is After arranging the bead part as a member to be fixed to the rim and forming it into a toroid shape, the tread is attached to the center of the outer periphery and the side wall is attached to the radially outer side to form the side part. Make a sulfur tire.

Thereafter, a tire is obtained by heating and pressurizing the produced unvulcanized tire in a vulcanizer. The vulcanization process can be carried out by applying known vulcanization means. The vulcanization temperature is, for example, more than 120°C and less than 200°C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the following, a motorcycle tire (for rear wheel) having a tire size of 190/50ZR17 having the structure shown in FIG. 1 was manufactured, and the steering stability during high-speed turning was evaluated.

1. Preparation of Belt Layer First, a belt layer was prepared according to the following procedure.

(1) Production of coated rubber composition First, a coated rubber composition was produced.

Specifically, 100 parts by mass of NR (RSS3), 55 parts by mass of carbon black (Show Black N550 manufactured by Cabot Japan Co., Ltd.: N ₂ SA = 42 m ² /g), a curable resin component (Taoka Chemical Co., Ltd. ) 5 parts by mass of Sumikanol 620: modified resorcinol resin), 3 parts by mass of curing agent (Sumikanol 507: methylene donor, manufactured by Taoka Chemical Co., Ltd.), organic acid cobalt (DICNATE NBC-2, manufactured by DIC Corporation) : Boron cobalt neodecanoate, cobalt content 22.5% by mass) 1 part by mass, zinc oxide (zinc white No. 1 manufactured by Mitsui Mining & Mining Co., Ltd.) 11 parts by mass, anti-aging agent -1 (Ouchi Shinko Chemical Industry Co., Ltd.) 1 part by mass of Nocrack 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Co., Ltd., Antioxidant-2 (Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd.): (2,2,4-trimethyl-1,2-dihydroquinoline) 0.5 parts by mass, stearic acid (stearic acid "Tsubaki" manufactured by NOF Corporation) 1 part by mass, sulfur (Tsurumi Chemical Industry Co., Ltd.) 7 parts by mass of powdered sulfur manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., and 1.2 parts by mass of a vulcanization accelerator (Noxela DZ: N,N-dicyclohexyl-2-benzothiazolylsulfenamide manufactured by Ouchi Shinko Chemical Co., Ltd.). The materials other than sulfur and the vulcanization accelerator were kneaded for 5 minutes at 150° C. using a Banbury mixer to obtain a kneaded product.

Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes at 80° C. using open rolls to obtain a coated rubber composition.

(2) Preparation of belt layer Steel cords having the cord configurations shown in Tables 2 to 5 are arranged in 25 ends/5 cm, and the coated rubber composition obtained above is applied to the top and bottom of the steel cords. Each belt layer was obtained by coating to a total thickness of 1.15 mm.

In addition, the presence or absence of buckling points, compressive rigidity value, and bending rigidity value of each steel cord were measured in advance according to the method described above. The measurement results are shown in Tables 2 to 5.

2. Manufacture of Tread Rubber Composition Next, a tread rubber composition was manufactured according to the following procedure, and then molded into tread rubber.

(1) Compounding materials First, each compounding material shown below was prepared.

(a) Rubber component (a) SBR: Tuffden 3830 manufactured by Asahi Kasei Corporation (S-SBR: styrene content: 33% by mass, vinyl bond amount: 31% by mass, 37.5% oil extended product)
(b) BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (Hi-cis BR synthesized using a Co-based catalyst: cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

(b) Compounding materials other than rubber components (a) Carbon black: Showblack N110 manufactured by Cabot Japan Co., Ltd.
(BET value 142m ² /g)
(b) Silica: Ultrasil VN3 manufactured by Evonik Industries
(BET specific surface area: 175m ² /g)
(c) Silane coupling agent: Silane coupling agent Si69 manufactured by Evonik Industries
(d) Oil: Diana Process NH-70 manufactured by Idemitsu Kosan Co., Ltd.
(e) Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
(F) Resin: Syltraxx4401 manufactured by Arizona Chemical Company
(α-methylstyrene resin, softening point 85°C)
(g) Liquid SBR: RICON100 manufactured by Cray Valley (random copolymer, styrene content: 25% by mass, vinyl content: 70%, Mn: 4500)
(h) Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.
(N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine)
(li) Stearic acid: Beaded stearic acid “Tsubaki” manufactured by NOF Corporation
(n) Zinc oxide: “Ginrei R” manufactured by Toho Zinc Co., Ltd.
(Le) Sulfur: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (powdered sulfur containing 5% oil)
(w) Vulcanization accelerator: Noxel-NS manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(N-tert-monobutyl-2-benzothiazolylsulfenamide)

(2) Production of tread rubber composition According to each of the formulations A to E shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a Banbury mixer. A kneaded product was obtained. Note that each blending amount is in parts by mass.

Thereafter, using each of the obtained tread rubber compositions, vulcanized rubber pieces with a length of 40 mm and a width of 4 mm were produced as rubber test pieces for measuring viscoelasticity. Then, each of the obtained rubber test pieces for measuring viscoelasticity was tested using a GABO Iplexer at temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, deformation mode: extension. The complex modulus of elasticity E ^* (MPa) was measured under the following conditions. The measurement results are shown in Table 1 and Tables 2 to 5.

(3) Production of tread rubber Next, each of the obtained tread rubber compositions was extrusion molded into a predetermined shape to produce tread rubber.

3. Manufacture of Tire The belt layer and tread rubber obtained above were bonded together with other tire members to form an unvulcanized tire, and press vulcanized for 10 minutes at 170°C. The test tires of Examples 1 to 12 shown in Table 4 and the test tires of Comparative Examples 1 to 10 shown in Tables 4 and 5 were manufactured.

4. Calculation of Parameters In addition to manufacturing the tires described above, as a parameter for evaluation, the product of the total cross-sectional area S (mm ² ) of the steel filaments in the cross section of each steel cord and each complex modulus of elasticity E ^* (MPa) (S×E ^* ) and the product (FR×E*) of the bending stiffness value FR of each steel cord and each complex modulus of elasticity E ^* (MPa ⁾ were determined. Furthermore, the ratio (L2/L1) of the length L2 (mm) of the belt layer on the outside in the tire width direction to the length L1 (mm) in the tire width direction of the belt layer on the inside in the tire radial direction was determined. Furthermore, the ratio (Lm/Tw) of the maximum length Lm (mm) of the belt layer in the tire width direction to the tread width Tw (mm) was determined. The results are shown in Tables 2 to 5.

5. Performance evaluation test (evaluation of maneuvering stability during high-speed turns)
Each test tire was mounted on a rim (MT 6.00 x 17), mounted on the rear wheel of a large motorcycle (1000 cc) at an internal pressure of 200 kPa, and run on a dry asphalt tire test course. Drivers sensuously evaluated the change in handling when changing lanes while driving at 120 km/h on a 5-point scale from 1 (feel a significant change) to 5 (feel almost no change). did. Then, the total score of the evaluations by 20 drivers was calculated.

Next, the result in Example 1 was set as 100, and the result was expressed as an index based on the formula below to evaluate the steering stability during high-speed turns. The larger the value, the better the steering stability during high-speed turns.
Steering stability = [(results of test tires)/(results of example 1)] x 100

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. Various changes can be made to the above embodiments within the same and equivalent scope as the present invention.

The present invention (1) is
A motorcycle tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer disposed outside the carcass in the tire radial direction and inside the tread portion,
The belt layer is a steel belt layer having a steel cord,
The steel cord is a steel cord having an m×n configuration in which n strands of m steel filaments are twisted together in the same direction as the steel filaments, and m is 1 or more and 3 or less, The n is 2 or more and 6 or less,
The diameter of the steel filament is 0.15 mm or more and 0.25 mm or less,
The rubber composition constituting the tread portion has a complex modulus of elasticity E ^* (MPa ) is a rubber composition with a pressure of 5.0 MPa or more,
The product (S×E ^* ) of the total cross-sectional area S (mm ² ) of the steel filament in the cross section of the steel cord and the complex modulus of elasticity E ^* (MPa) is 2.00 or less. This is a motorcycle tire.

The present invention (2) is
The motorcycle tire according to the present invention (1), wherein the complex elastic modulus E ^* (MPa) is 6.5 MPa or more.

The present invention (3) is
The motorcycle tire according to the present invention (1) or (2), wherein the above (S×E ^* ) is less than 1.70.

The present invention (4) is
The steel cord has a compression rigidity value of 65 N/mm or less, and is a motorcycle tire in any combination with any one of the present inventions (1) to (3).

The present invention (5) is
The steel cord is characterized in that it is a steel cord without a buckling point, and is a motorcycle tire in any combination with any one of the present inventions (1) to (4).

The present invention (6) is
A motorcycle tire in any combination with any one of the present invention (1) to (5), characterized in that the bending rigidity value of the steel cord is 2.5 × 10 ^-3 N m or less. .

The present invention (7) is
The motorcycle tire according to the present invention (6), wherein the steel cord has a bending rigidity value of 2.0×10 ⁻³ N·m or less.

The present invention (8) is
The motorcycle tire according to the present invention (7), wherein the steel cord has a bending rigidity value of 1.5×10 ⁻³ N·m or less.

The present invention (9) is
The present invention is characterized in that the product (FR×E ^* ) of the bending stiffness value FR and the complex modulus of elasticity E ^* (MPa) of the steel cord is 25×10 ⁻³ (MPa・N・m) or less, This is a motorcycle tire in any combination with any one of (1) to (8).

The present invention (10) is
The motorcycle tire according to the present invention (9), wherein the (FR×E ^* ) is 15×10 ⁻³ (MPa·N·m) or less.

The present invention (11) is
The motorcycle tire according to the present invention (10), wherein the (FR×E ^* ) is 10×10 ⁻³ (MPa·N·m) or less.

The present invention (12) is
The motorcycle tire is characterized in that organic acid cobalt is blended in the coating rubber of the belt layer, and is any combination of the present invention (1) to (11).

The present invention (13) is
In the motorcycle tire according to the present invention (12), the content of the organic acid cobalt is 0.05 parts by mass or more in terms of cobalt based on 100 parts by weight of the rubber component. be.

The present invention (14) is
The belt layer is multilayered,
In at least one set of radially adjacent belt layers of the multilayered belt layer tire, an average distance D (mm) between steel cords is 0.6 mm or less. A motorcycle tire in any combination with any one of inventions (1) to (13).

The present invention (15) is
The belt layer is multilayered,
In at least one set of radially adjacent sets of belt layers of the multilayered belt layer tire, the angle between the steel cords in each belt layer in the tread portion in the tire circumferential direction is 65° or less This is a motorcycle tire in any combination with any one of the present inventions (1) to (13).

The present invention (16) is
The motorcycle tire according to the present invention (15), wherein the angle between the steel cords in each belt layer in the tire circumferential direction is 60° or less.

The present invention (17)
The belt layer is multilayered,
In mutually adjacent belt layers, the ratio (L2/L1) of the tire width direction length L2 (mm) of the tire radially outer belt layer to the tire width direction length L1 (mm) of the tire radially inner belt layer. is more than 1.00, and is a motorcycle tire in any combination with any one of the present inventions (1) to (16).

The present invention (18)
According to the present invention (1) to (17), the rubber composition of the tread portion is a rubber composition containing 25% by mass or less of styrene in the rubber component and having a Tg of -18°C or higher. It is a motorcycle tire in any combination with either.

The present invention (19)
The tread portion is characterized in that it is divided into an inner region and an outer region sandwiching the inner region in the tire width direction. It is a motorcycle tire.

The present invention (20)
The present invention (19) characterized in that the rubber composition constituting the outer region of the tread portion is a rubber composition containing 25% by mass or less of styrene in the rubber component and having a Tg of -18°C or higher. This is a motorcycle tire described in .

The present invention (21)
The present invention (1) to (20) is characterized in that the ratio (Lm/Tw) of the maximum length Lm (mm) of the belt layer in the tire width direction to the tread width Tw (mm) is 1.00 or more. A motorcycle tire in any combination with any of the above.

1 Tire 2 Tread portion 3 Sidewall portion 4 Bead portion 5 Bead core 6 Carcass 6a Ply body portion 6b Ply folded portion 7 Belt layer 8 Bead apex rubber 9 Belt reinforcement layer 10 Steel cord 12 Strand C Tire equator f Steel filament G Covered rubber IN Inner region K0 Correction samples K1 to K3 Measurement sample OUT Outer region Te Tread end Tw Tread width

Claims (21)

A motorcycle tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer disposed outside the carcass in the tire radial direction and inside the tread portion,
The belt layer is a steel belt layer having a steel cord,
The steel cord is a steel cord having an m×n configuration in which n strands of m steel filaments are twisted together in the same direction as the steel filaments, and m is 1 or more and 3 or less, The n is 2 or more and 6 or less,
The diameter of the steel filament is 0.15 mm or more and 0.25 mm or less,
The rubber composition constituting the tread portion has a complex modulus of elasticity E ^* (MPa ) is a rubber composition with a pressure of 5.0 MPa or more,
The product (S×E ^* ) of the total cross-sectional area S (mm ² ) of the steel filament in the cross section of the steel cord and the complex modulus of elasticity E ^* (MPa) is 2.00 or less. Motorcycle tires. The motorcycle tire according to claim 1, wherein the complex modulus of elasticity E ^* (MPa) is 6.5 MPa or more. The motorcycle tire according to claim 1 or 2, wherein the (S×E ^* ) is less than 1.70. The motorcycle tire according to any one of claims 1 to 3, wherein the steel cord has a compression rigidity value of 65 N/mm or less. The motorcycle tire according to any one of claims 1 to 4, wherein the steel cord is a steel cord without a buckling point. The motorcycle tire according to any one of claims 1 to 5, wherein the steel cord has a bending rigidity value of 2.5×10 ⁻³ N·m or less. The motorcycle tire according to claim 6, wherein the steel cord has a bending rigidity value of 2.0×10 ⁻³ N·m or less. The motorcycle tire according to claim 7, wherein the steel cord has a bending rigidity value of 1.5×10 ⁻³ N·m or less. Claim characterized in that the product (FR×E ^* ) of the bending stiffness value FR and the complex modulus of elasticity E ^* (MPa) of the steel cord is 25×10 ⁻³ (MPa·N·m) or less. The motorcycle tire according to any one of claims 1 to 8. The motorcycle tire according to claim 9, wherein the (FR×E ^* ) is 15×10 ⁻³ (MPa·N·m) or less. The motorcycle tire according to claim 10, wherein the (FR×E ^* ) is 10×10 ⁻³ (MPa·N·m) or less. The motorcycle tire according to any one of claims 1 to 11, wherein the coating rubber of the belt layer contains organic acid cobalt. The motorcycle tire according to claim 12, wherein the content of the organic acid cobalt is 0.05 parts by mass or more in terms of cobalt based on 100 parts by weight of the rubber component. The belt layer is multilayered,
A claim characterized in that in at least one set of radially adjacent belt layers of the multilayered belt layer tire, an average distance D (mm) between steel cords is 0.6 mm or less. The motorcycle tire according to any one of claims 1 to 13. The belt layer is multilayered,
In at least one set of radially adjacent sets of belt layers of the multilayered belt layer tire, the angle between the steel cords in each belt layer in the tread portion in the tire circumferential direction is 65° or less The motorcycle tire according to any one of claims 1 to 13, characterized in that: The motorcycle tire according to claim 15, wherein the angle between the steel cords in each belt layer in the tire circumferential direction is 60° or less. The belt layer is multilayered,
In mutually adjacent belt layers, the ratio (L2/L1) of the tire width direction length L2 (mm) of the tire radially outer belt layer to the tire width direction length L1 (mm) of the tire radially inner belt layer. 17. The motorcycle tire according to any one of claims 1 to 16, wherein: is greater than 1.00. Any one of claims 1 to 17, wherein the rubber composition of the tread portion contains 25% by mass or less of styrene in the rubber component and has a Tg of -18°C or higher. The motorcycle tire according to item 1. The motorcycle according to any one of claims 1 to 18, wherein the tread portion is divided in the tire width direction into an inner region and an outer region sandwiching the inner region. tire. 20. The rubber composition constituting the outer region of the tread portion is a rubber composition containing 25% by mass or less of styrene in the rubber component and having a Tg of -18°C or higher. motorcycle tires. Any one of claims 1 to 20, characterized in that the ratio (Lm/Tw) of the maximum length Lm (mm) of the belt layer in the tire width direction to the tread width Tw (mm) is 1.00 or more. The motorcycle tire according to item 1.

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