Tire

Abstract

To provide a tire with excellent durability.SOLUTION: In a tire with two or more belt layers, the belt layer includes a belt ply having a steel monofilament and a coated rubber. In a tire radial cross section, when a tire width direction outer end position of the belt ply that is the widest in a tire axial direction among the belt ply is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of the arranged steel monofilament per 10 mm in the tire width direction in a region from a tire equatorial plane of the belt ply having the widest width in the tire axial direction to a point Q that is 80% of a tire axial distance L to the point P, to the number E2 (pieces / 10 mm) of the arranged steel monofilament per 10 mm in the tire width direction from the point Q to the point P, is less than 0.90. A tire radial distance S between an outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a tire. [Background technology]

[0002] 2. Description of the Related Art Various methods for improving various tire performances have been studied, and in recent years, there has been a particular demand for improved durability. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to solve the above problems and to provide a tire having excellent durability. [Means for solving the problem]

[0004] The present invention relates to a tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q that is 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 50 mm in the tire width direction from the point Q to the point P is less than 0.90; The tire has a radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction of the tire, of 0.80 mm or more. Effect of the Invention

[0005] According to the present invention, a tire having two or more belt layers, the belt layers having a belt ply including steel monofilaments and coated rubber, the E2 / E1 being less than 0.90, and the S being 0.80 mm or more, can be provided, thereby providing a tire having excellent durability. [Brief description of the drawings]

[0006] [Figure 1] 1 is a tire meridian cross-sectional view of a pneumatic tire of the present invention. FIG. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a belt layer and a band layer of the tire of FIG. 1. [Diagram 3] FIG. 2 is an enlarged cross-sectional view of the tire shown in FIG. 1 between a belt layer and a band layer PQ. [Figure 4] 2 is an enlarged cross-sectional view of a belt layer and a band layer of the tire in FIG. 1 near the tire equatorial plane. [Diagram 5] FIG. 2 is an enlarged cross-sectional view showing the vicinity of the tread portion of the tire shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention relates to a tire having two or more belt layers, the belt layer having a belt ply having steel monofilaments and a coating rubber, in which, in a radial cross section of the tire, when a point P is defined as an outer end position in the tire width direction of the belt plies having the widest width in the tire axial direction among the belt plies, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the widest belt ply to a point Q that is 80% of the tire axial distance L to point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from point Q to point P is less than 0.90, and a radial distance S of the tire between an outermost steel filament in the tire width direction of a belt ply adjacent to the widest belt ply in the tire axial direction and a steel filament of the widest belt ply in the tire axial direction is 0.80 mm or more.

[0008] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that they are due to the following mechanism. It has been proposed to use single-wire steel cords (steel monofilaments) in the belt layer to reduce the weight of tires, among other things. However, because single-wire steel cords are not twisted, the rigidity of the belt layer increases, and there are concerns that the tread will be less likely to deform when in contact with the ground, resulting in increased localized distortion and reduced durability. On the other hand, it is believed that the single filament becomes rigid and is less likely to deform when it comes into contact with the ground. Therefore, for the widest belt ply that forms the belt layer, the ratio of the number of filaments arranged in the shoulder portion E2 to the number of filaments arranged in the crown portion E1 is set to less than 0.90, and the steel cord density in the vicinity of the end portion of the belt layer is reduced, so that the shoulder portion of the tread is more likely to come into contact with the ground when rolling, and the entire tread is more likely to come into contact with the road surface. It is therefore believed that it is possible to easily suppress the occurrence of localized distortion. Furthermore, by setting the tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply that is widest in the tire axial direction and the steel filament of the belt ply that is widest in the tire axial direction to 0.80 mm or more and setting the tire radial distance of the steel filaments to a predetermined distance or more, it is considered that the spacing between the belt plies in the vicinity of the shoulder portion, which will be significantly deformed when the belt plies come into contact with the ground, will be increased, making it possible to suppress stress concentration in the vicinity of the belt end portion. As a result of the above, it is believed that the ground contact of the tread portion is improved, the occurrence of localized distortion is suppressed, and stress concentration near the shoulder portions, where deformation is large, is also easily suppressed, resulting in improved durability.

[0009] In this way, the problem (purpose) of improving durability is solved by using a configuration with belt plies that satisfy "E2 / E1 less than 0.90" and "S equal to or greater than 0.80 mm." In other words, the parameters "E2 / E1 less than 0.90" and "S equal to or greater than 0.80 mm" do not define the problem (purpose); the problem of this application is to improve durability, and a configuration that satisfies these parameters is used as a means to achieve this.

[0010] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. However, this is merely one embodiment, and the tire of the present invention is not limited to the following embodiment.

[0011] FIG. 1 is a tire meridian cross-sectional view including a tire rotation axis of a pneumatic tire 2 (pneumatic tire) according to this embodiment in a normal state.

[0012] In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured under normal conditions. In this specification, the term "normal condition" refers to a condition in which the tire is mounted on a normal rim (not shown), inflated to normal internal pressure, and no load is applied.

[0013] When it is not possible to measure with the tire mounted on a regular rim, the dimensions and angles of each part in the meridian section of the tire are measured by cutting the tire along a plane including the axis of rotation, and the distance between the left and right beads in the cross section is measured so that it corresponds to the distance between the beads of the tire mounted on a regular rim.

[0014] "Genuine rim" refers to the rim that is specified for each tire by the standard system that includes the standard on which the tire is based, for example, "Standard rim" in the applicable size listed in the "JATMA YEAR BOOK" for JATMA (Japan Automobile Tire Manufacturers Association), "Measuring Rim" in the "STANDARDS MANUAL" for ETRTO (The European Tire and Rim Technical Organisation), and "Design Rim" in the "YEAR BOOK" for TRA (The Tire and Rim Association, Inc.). Refer to JATMA, ETRTO, and TRA in that order, and follow the standard if there is an applicable size at the time of reference. In the case of a tire not specified in the standard, it refers to the rim that can be assembled to the rim and can hold internal pressure, that is, the rim with the smallest rim diameter and the next narrowest rim width among the rims that do not leak air from between the rim and tire.

[0015] "Regular internal pressure" refers to the air pressure specified for each tire by each standard in the standard system including the standard on which the tire is based. For JATMA, it refers to the "Maximum Air Pressure", for ETRTO, it refers to the "INFLATION PRESSURE", and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with "regular rims", it refers to JATMA, ETRTO, TRA in that order and follows those standards. For tires not specified in the standard, it refers to the regular internal pressure (250kPa or more) of another tire size (specified in the standard) that is specified with the regular rim as the standard rim. Note that if multiple regular internal pressures of 250kPa or more are specified, it refers to the smallest value among them.

[0016] In this specification, the term "normal load" refers to the load that is determined for each tire by each standard in the standard system including the standard on which the tire is based, and is the maximum load capacity in the case of JATMA, the "LOAD CAPACITY" in the case of ETRTO, and the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA. As in the case of the "normal rim" and "normal internal pressure" mentioned above, JATMA, ETRTO, and TRA are referred to in that order and their standards are followed. In the case of a tire not determined by a standard, the normal load W is calculated as follows: L Request. V = {(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt W L =0.000011×V+175 W L :Normal load (kg) V: Virtual volume of the tire (mm 3 ) Dt: Tire outer diameter (mm) Ht: Section height of the tire (mm) Wt: tire section width (mm)

[0017] The "section width Wt (mm)" of a tire is the maximum width between the outer surfaces of the sidewalls when the tire is in its normal condition, excluding any patterns or lettering on the sidewalls.

[0018] The "outer diameter Dt (mm)" of a tire refers to the outer diameter of the tire under normal conditions.

[0019] The "section height Ht (mm)" of a tire refers to the radial height of the tire at its radial cross section, and corresponds to half the difference between the tire's outer diameter Dt and the rim diameter R, where R is the tire's rim diameter (mm). In other words, the section height Ht can be calculated by (Dt-R) / 2.

[0020] 1, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tread portion 4 includes a cap layer 30 and a base layer .

[0021] Although FIG. 1 shows an example of a two-layer tread portion 4 consisting of a cap layer 30 and a base layer 28, the tread portion 4 may be a single-layer tread or a tread having a structure of three or more layers.

[0022] In the tire 2, each sidewall 6 extends substantially radially inward from an end of the tread portion 4. A radially outer portion of each sidewall 6 is joined to the tread portion 4. A radially inner portion of each sidewall 6 is joined to a clinch 10. The sidewalls 6 can prevent damage to the carcass 14.

[0023] 1 is located between the tread portion 4 and the sidewall 6. The wing 8 is joined to each of the tread portion 4 and the sidewall 6.

[0024] Each clinch 10 is located approximately radially inward of the sidewall 6 and has at least one or more portions that come into contact with the rim.

[0025] The carcass 14 includes a carcass ply 36. In the tire 2, the carcass 14 is made up of one carcass ply 36, but may be made up of two or more carcass plies.

[0026] In the tire 2, the carcass ply 36 is laid between the bead cores 32 on both sides and extends along the tread portion 4 and the sidewall 6. The carcass ply 36 is folded back from the inside to the outside in the axial direction around each bead core 32. By this folding back, the carcass ply 36 is formed with a main portion 36a and a pair of folded back portions 36b. That is, the carcass ply 36 has the main portion 36a and a pair of folded back portions 36b.

[0027] Each bead core 32 includes a bead apex 34 extending radially outward from the bead core 32. The bead core 32 is preferably ring-shaped and includes a wound non-stretchable wire. The bead apex 34 tapers radially outward.

[0028] Although not shown, the carcass ply 36 is preferably made of a number of parallel cords and a topping rubber. The absolute value of the angle that each cord makes with respect to the equatorial plane CL is preferably 75° to 90°. In other words, the carcass 14 preferably has a radial structure.

[0029] The belt layer 16 in FIG. 1 is located radially inward of the tread portion 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. The belt layer 16 is formed of two or more layers, and in the tire 2 in FIG. 1, the belt layer 16 is composed of two layers, an inner layer 38 and an outer layer 40. As is clear from FIG. 1, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40 in the axial direction. In this tire 2, the axial width of the belt layer 16 is preferably 0.6 times or more and 0.9 times or less of the cross-sectional width of the tire 2.

[0030] In the belt layer 16, each of the layers constituting the inner layer 38, the outer layer 40, and other belt layers arranged as required is preferably made of a large number of parallel single-wire steel cords (steel monofilaments) and a topping rubber (coating rubber). In other words, each layer constituting the belt layer 16 includes a large number of parallel steel monofilaments.

[0031] FIG. 2 is an enlarged cross-sectional view of the belt layer 16 (the inner layer 38 and the outer layer 40) and the band layer 18. As shown in Fig. 2, the belt ply 17 includes a belt cord 17A and a topping rubber 17B (coating rubber) that covers the belt cord 17A. The belt cord 17A is a single-wire steel cord (steel monofilament). In this embodiment, the belt cord 17A is a single wire with a circular cross section, but the present invention is not limited to this, and the cross section may be of another shape, such as an elliptical or polygonal shape. In addition, these filaments may be pre-formed from the viewpoint of durability and the like.

[0032] 2, the belt ply 17 includes, for example, a first belt ply (inner layer 38) and a second belt ply (outer layer 40) adjacent to the first belt ply (inner layer 38) in the tire radial direction. The second belt ply (outer layer 40) is located outside the first belt ply (inner layer 38) in the tire radial direction.

[0033] In this embodiment, the belt cord 17A is formed of a steel monofilament, and such a belt cord 17A suppresses deformation during running of the belt ply 17. The belt cord 17A of the first belt ply (inner layer 38) and the belt cord 17A of the second belt ply (outer layer 40) may have the same shape or different shapes.

[0034] The diameter D of the steel monofilament (single-wire steel cord) is preferably 0.25 mm or more, more preferably 0.30 mm or more, even more preferably 0.35 mm or more, and is preferably 0.45 mm or less, more preferably 0.42 mm or less, even more preferably 0.40 mm or less. Within the above ranges, the effects can be suitably obtained. The diameter of a steel monofilament (single-wire steel cord) refers to the outer diameter of the filament, and is the outer diameter of the steel monofilament measured on a cross section perpendicular to the length direction of the steel monofilament. In cases where it is difficult to determine the outer diameter uniquely, such as when the cross section of the steel monofilament perpendicular to the length direction is flat, the average value of the long diameter of the filament and the maximum diameter perpendicular to the long diameter is treated as the outer diameter of the filament.

[0035] The mechanism by which greater effects are obtained by adjusting the filament diameter within the above range, particularly 0.25 to 0.42 mm, is not clear; however, it is believed that by setting the cord diameter to a specified value or less, the rigidity of the belt layer is prevented from becoming too high, improving ground contact, while by setting the cord diameter to a specified value or more, it becomes easier to prevent the cord from breaking, which is presumably why durability is improved.

[0036] The belt cord 17A is preferably inclined at an angle of, for example, 15 to 45 degrees with respect to the tire circumferential direction. The angle between the belt cord 17A and the tire circumferential direction is the angle between the belt cord 17A and the tire circumferential direction on the tire equatorial plane. The angle between the belt cord 17A and the tire circumferential direction can be measured by peeling off the tread portion of the tire and exposing the belt cord 17A on the tire surface.

[0037] Although not particularly limited, it is desirable that the belt cord 17A of the first belt ply (inner layer 38) and the belt cord 17A of the second belt ply (outer layer 40) are arranged with inclinations in opposite directions relative to the tire circumferential direction so as to intersect with each other.

[0038] From the viewpoint of adhesion to the rubber composition that covers the periphery of the belt cord 17A, the surface of the belt cord 17A is preferably plated with copper and zinc. In addition to the copper and zinc, it is more preferable that the belt cord 17A is plated with a metal element whose ionization tendency is between that of copper and zinc, such as cobalt, nickel, bismuth, or antimony.

[0039] In addition, the belt cord 17A preferably has a layer of a polybenzoxazine compound on the surface thereof from the viewpoint of adhesion to the surrounding rubber composition.

[0040] The topping rubber 17B (coating rubber) that covers the belt cord 17A desirably contains, in addition to well-known rubber materials, phenolic thermosetting resins, silica, salts of organic fatty acids with metals whose ionization tendency is between copper and zinc, such as the above-mentioned cobalt, nickel, bismuth, and antimony, and polybenzoxazine compounds.

[0041] In the tire 2, the belt layer 16 has a belt ply including a belt cord 17A made of a steel monofilament and a topping rubber 17B (coating rubber), In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, The ratio (E2 / E1) of the number E1 (pieces / 10 mm) of steel monofilaments arranged per 10 mm in the tire width direction in a region from the tire equatorial plane CL of the belt ply that is widest in the tire axial direction to point Q, which is 80% of the tire axial distance L to point P, to the number E2 (pieces / 10 mm) of steel monofilaments arranged per 10 mm in the tire width direction from point Q to point P, is less than 0.90.

[0042] E2 / E1 is preferably 0.85 or less, more preferably 0.82 or less, and even more preferably 0.80 or less. There is no particular lower limit, but it is preferably 0.50 or more, more preferably 0.60 or more, and even more preferably 0.65 or more. Within the above range, the effect can be suitably obtained.

[0043] E1 and E2 can be adjusted as appropriate by adjusting the number of belt cords arranged in the belt layer when manufacturing a tire. Also, the ratio of E1 to E2 (E2 / E1) can be adjusted by making the outer diameter of the belt layer end side smaller than the outer diameter of the mold in the tire before vulcanization.

[0044] In the present invention, the "point P at the outer end position in the tire width direction" refers to the outermost location (end) in the tire width direction of the belt ply having the widest axial width among the belt plies forming the belt layer. In the case of the belt layer 16 consisting of the inner layer 38 and the outer layer 40 in Fig. 1, the outer end of the inner layer 38 extending from the outer layer 40 to the outside in the tire axial direction is the position P of the outer end of the belt layer 16 in the tire axial direction.

[0045] "The tire axial distance L from the tire equatorial plane of the belt ply having the widest axial width to the point P" refers to the linear distance in the tire axial direction from the tire equatorial plane CL to the position P. In the case of the belt layer 16 consisting of the inner layer 38 and the outer layer 40 in FIG. 1, it is the linear distance in the tire axial direction from the tire equatorial plane CL to the outer end P of the inner layer 38.

[0046] "Point Q at 80% of the tire axial distance L from the tire equatorial plane of the belt ply having the widest axial width to point P" refers to a position at a distance of 80% of L from the tire equatorial plane toward the tire axially outer side of the straight-line distance L in the tire axial direction from the tire equatorial plane CL to the position P. In the case of the belt layer 16 consisting of the inner layer 38 and the outer layer 40 in Fig. 1, it is a position at a distance of 80% of the straight-line distance L from the tire equatorial plane CL toward the tire axially outer side.

[0047] In the tire radial cross section shown in Fig. 1 etc., the number of steel monofilaments arranged per 10 mm in the tire width direction (ends) E1 (ends / 10 mm) in the region L1 from the tire equatorial plane CL to point Q of the belt ply having the widest tire axial width is preferably 7.0 ends / 10 mm or more, more preferably 8.5 ends / 10 mm or more, even more preferably 11.2 ends / 10 mm or more, particularly preferably 12.0 ends / 10 mm or more, and preferably 15.5 ends / 10 mm or less, more preferably 14.5 ends / 10 mm or less, and even more preferably 14.0 ends / 10 mm or less. Within the above ranges, the effect can be preferably obtained.

[0048] The mechanism by which greater effectiveness can be achieved by adjusting E1 within the above range is not clear, but is presumed to be as follows. It is assumed that this high-end specification allows the board to absorb protruding objects such as nails in a manner similar to that of a steel plate, thereby improving durability.

[0049] In the tire radial cross section shown in Fig. 1 etc., the number of steel monofilaments arranged (ends) E2 (ends / 10mm) per 10mm in the tire width direction in the region L2 from point Q to point P of the belt ply which is the widest in the tire axial direction is preferably 5.0 ends / 10mm or more, more preferably 6.8 ends / 10mm or more, even more preferably 7.5 ends / 10mm or more, and preferably 10.2 ends / 10mm or less, more preferably 9.5 ends / 10mm or less, even more preferably 9.0 ends / 10mm or less. Within the above ranges, the effects can be preferably obtained.

[0050] It should be noted that E1 and E2 are the numbers of steel monofilaments arranged per 10 mm width in the belt ply that is the widest in the axial direction of the tire and that provides the point P described above. E1 and E2 can be measured, for example, by the following method. First, the tire is cut out in the radial direction, and fixed so that the distance between the bead cores 32 in this cross section is the same as when mounted on a regular rim. Then, the distance L between the outermost point P of the belt layer in the width direction and the tire equatorial plane CL is calculated. Next, the 80% position Q of the distance L is calculated, and the intersection point Q' between a straight line parallel to the tire radial direction passing through point Q and the belt ply with the widest width in the tire axial direction is obtained. Then, the number of arranged steel monofilaments per 10 mm in the tire width direction E1 is calculated from the number of arranged steel monofilaments in the belt ply between the tire equatorial plane CL and point Q' and the actual length of the belt ply. Similarly, E2 can be calculated from the number of steel monofilaments arranged in the belt ply that is the widest in the axial direction of the tire between point Q' and point P, and the actual length of the belt ply. In addition, when the belt ply having the widest axial width draws an arc as shown in FIG. 1, the actual length of the belt ply is not the straight-line distance from the tire equatorial plane CL to point Q', but the length of the arc that the belt ply draws in the section from the tire equatorial plane CL to point Q'.

[0051] FIG. 3 is an enlarged cross-sectional view of the belt layer 16 (the inner layer 38 and the outer layer 40) and the band layer 18 between PQ. 3, the belt cord 17A2 in the second belt ply (outer layer 40) is the outermost belt cord in the tire width direction among the belt cords 17A in the second belt ply. The distance S in the tire radial direction between the belt cord 17A2 and the belt cord 17A1 in the first belt ply (inner layer 38) is 0.80 mm or more.

[0052] In the tire 2, each of the belt plies constituting the two or more belt layers 16 includes a belt cord 17A made of a steel monofilament and a topping rubber 17B (coating rubber), and the tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more.

[0053] FIG. 3 shows a tire in which no other rubber sheets or the like are provided between the adjacent inner layer 38 and outer layer 40, but the tire may further include a rubber sheet or the like between the adjacent belt plies.

[0054] S is preferably 0.85 mm or more, more preferably 0.95 mm or more, and even more preferably 1.00 mm or more. The upper limit is not particularly limited, but is preferably 1.70 mm or less, more preferably 1.50 mm or less, even more preferably 1.30 mm or less, and particularly preferably 1.20 mm or less. The lower limit is not particularly limited, but within the above range, the effect can be preferably obtained.

[0055] Here, in the tire 2 of the present invention, at least one of the belt plies adjacent to the belt ply that provides the position P of the outer end of the belt ply in the tire width direction may satisfy "S is 0.80 mm or more". For example, in the case of a two-layer belt ply, the belt ply adjacent to the belt ply that provides the position P may satisfy "S is 0.80 mm or more", and in the case of a three-layer belt ply, at least one of the two belt plies adjacent to the belt ply that provides the position P may satisfy "S is 0.80 mm or more", but it is preferable that both layers satisfy it.

[0056] In the present invention, the "outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply with the widest axial width in the tire" refers to the belt cord (steel monofilament) in the belt ply adjacent to the belt ply that provides the position (end) P that is the outermost in the tire width direction in a belt layer composed of two or more belt plies, and the belt cord that is the outermost in the tire width direction. In the case of the belt layer 16 composed of two belt plies, the inner layer 38 and the outer layer 40 in Fig. 3, it means the belt cord 17A2 that is the outermost in the tire width direction among the belt cords (steel monofilament) in the outer layer 40 adjacent to the inner layer 38 that provides the position P. The "distance S in the tire radial direction between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply that is widest in the tire axial direction and the steel filament in the belt ply that is widest in the tire axial direction" is the straight-line distance in the tire radial direction between the outermost steel filament in the tire width direction in the belt ply adjacent to the belt ply that gives the position P of the outer end of the belt layer in the tire width direction and the steel filament in the belt ply that gives the position P. Here, when a straight line extending in the tire radial direction from the inner surface in the tire radial direction of the outermost steel filament in the tire width direction in the adjacent belt ply intersects with the outermost surface of the steel filament in the belt ply that gives the position P, the straight line distance in the tire radial direction from the inner surface in the tire radial direction to the outermost surface is S. In the case where a straight line extended in the tire radial direction from the inner surface in the tire radial direction of the outermost steel filament in the tire width direction in an adjacent belt ply does not intersect with the outermost surface of the steel filament in the belt ply that gives position P (such as when there is no cord on the straight line), the linear distance in the tire radial direction between the intersection point of the straight line extended in the tire radial direction from the inner surface in the tire radial direction and the straight line connecting the outer surfaces in the tire radial direction of two steel filaments close to that straight line in the steel filament in the belt ply that gives position P, and the inner surface in the tire radial direction is S. In the case of a tire further including a rubber sheet or the like between adjacent belt plies, the distance S is measured in the same manner for the tire including the adjacent belt plies disposed with the rubber sheet or the like therebetween. In the case of the belt layer 16 consisting of two belt plies, the inner layer 38 and the outer layer 40 in Fig. 3, a straight line extending in the tire radial direction from the inner surface in the tire radial direction of the outermost belt cord 17A2 in the outer layer 40 in the tire width direction does not intersect with the outermost surface of the belt cord 17A1 in the inner layer 38 that gives the position P, so the tire radial linear distance between the intersection point of the straight line extending in the tire radial direction from the inner surface in the tire radial direction of the belt cord 17A2 and the straight line connecting the outer surfaces in the tire radial direction of the two belt cords 17A close to the straight line, and the inner surface in the tire radial direction of the belt cord 17A2 is S. In addition, in the case of a tire further provided with a rubber sheet or the like between the inner layer 38 and the outer layer 40, the distance S is measured in the same manner in the state of the tire including the rubber sheet or the like.

[0057] FIG. 4 is an enlarged cross-sectional view of the belt layer 16 (the inner layer 38 and the outer layer 40) and the band layer 18 in the vicinity of the tire equatorial plane CL. 4, the belt cord 17A5 in the first belt ply (inner layer 38) is one of the belt cords 17A in the first belt ply that is disposed on the tire equatorial plane CL. The belt cord 17A6 in the second belt ply (outer layer 40) is one of the belt cords 17A in the second belt ply that is disposed on the tire equatorial plane CL.

[0058] In the tire 2, from the viewpoint of obtaining a better effect, the distance Sc between the steel monofilaments (single steel cords) at the tire equatorial plane in adjacent belt plies is desirably 0.15 to 0.50 mm. Sc is preferably 0.25 mm or more, more preferably 0.30 mm or more, even more preferably 0.36 mm or more, and is preferably 0.45 mm or less, more preferably 0.42 mm or less, even more preferably 0.40 mm or less. Within the above ranges, the effect can be suitably obtained.

[0059] In the present invention, "the distance Sc between steel monofilaments at the tire equatorial plane in adjacent belt layers" refers to the linear distance in the tire radial direction between the respective steel monofilaments present at the tire equatorial plane in the adjacent belt layers. In the case of a tire having two belt layers, an inner layer 38 and an outer layer 40 as shown in Fig. 4, it means the linear distance Sc in the tire radial direction between the belt cord 17A5 provided at the tire equatorial plane CL in the first belt ply (inner layer 38) and the belt cord 17A6 provided at the tire equatorial plane CL in the second belt ply (outer layer 40). When no steel monofilament is present at the tire equatorial plane, the distance means the linear distance in the tire radial direction between the steel monofilaments that are closest to the tire equatorial plane in the tire width direction.

[0060] The mechanism by which greater effects can be obtained by adjusting the distance Sc to the above range, particularly 0.25 to 0.45 mm, is not clear, but is presumed to be as follows. The shoulder portions are subject to a large amount of deformation when rolling, but by ensuring a sufficient distance between the cords of adjacent belt plies, stress concentration can be suppressed. On the other hand, the central portion is not subject to such a large amount of deformation, so by setting the thickness of the covering rubber layer of the belt layer to a specified value or less, the amount of rubber between the belt plies is reduced, making it easier to suppress heat accumulation. Furthermore, if the thickness of the covering rubber layer of the belt layer is too thin, the cords may come into contact with each other and break due to friction, but by making the thickness at least a certain level, breakage can be prevented. Therefore, it is presumed that durability is significantly improved.

[0061] Here, in the tire 2 of the present invention, it is preferable that at least one of the distances Sc between the steel monofilaments (single-wire steel cords) at the tire equatorial plane in the adjacent belt layers satisfies the above range. For example, in the case of a belt layer having a two-layer structure, it is preferable that the adjacent belt layers satisfy the above range. In the case of a belt layer having a three-layer structure, it is preferable that at least one of the adjacent belt layers satisfies the above range, and it is more preferable that all of the adjacent belt layers satisfy the above range.

[0062] From the viewpoint of obtaining a greater effect, it is desirable that the tire 2 has a product S×D of S (mm) and D (mm) of 0.22 or greater and 0.58 or less. The lower limit of S×D is preferably 0.24 or more, more preferably 0.28 or more, even more preferably 0.32 or more, particularly preferably 0.35 or more, and is preferably 0.54 or less, more preferably 0.50 or less, even more preferably 0.46 or less. Within the above ranges, the effect can be suitably obtained.

[0063] The mechanism by which greater effects are obtained by adjusting S×D within the above range is not clear, but is presumed to be as follows. When S / D is within the above range, the ground pressure applied to the shoulder and crown parts is uniform, and it is believed that the tire is less susceptible to damage. In other words, when S×D is small, the shoulder parts are thin, and the ground pressure is concentrated in the crown part, which leads to peeling in the crown part, and it is also believed that the tire always slips during driving, which leads to uneven wear. Conversely, when S×D is large, the shoulder parts are thick, so the ground pressure is biased to the shoulder parts, which is believed to easily develop into peeling at the ends of the belt layers. Therefore, it is presumed that the tire is less susceptible to damage as described above, and durability is improved.

[0064] From the standpoint of obtaining a greater effect, it is desirable that the tire 2 has a ratio S / Sc of the S (mm) and the Sc (mm) of 2.2 or greater and 4.0 or less. S / Sc is preferably 2.4 or more, more preferably 2.6 or more, and even more preferably 2.7 or more, and is preferably 3.8 or less, more preferably 3.6 or less, and even more preferably 3.4 or less. Within the above ranges, the effects can be suitably obtained.

[0065] The mechanism by which better effects are obtained by adjusting S / Sc to the above range is not clear, but is presumed to be as follows. When S / Sc is in the above range, the ground pressure applied to the shoulder and crown parts is uniform, and it is considered that the tire is less susceptible to damage. In other words, when S / Sc is small, the shoulder parts are thin, and the ground pressure is concentrated in the crown part, which leads to the occurrence of peeling in the crown part, and also leads to uneven wear because the tire always slips during driving. Conversely, when S / Sc is large, the shoulder parts are thick, so the ground pressure is biased to the shoulder parts, which is considered to easily develop into peeling at the ends of the belt layers. Therefore, it is presumed that the tire is less susceptible to damage as described above, and the durability is improved.

[0066] From the standpoint of obtaining a greater effect, it is desirable that the product (E2 / E1) of the ratio E2 (piece / 10 mm) to E1 (piece / 10 mm) and D (mm), that is, E2 / E1×D, of tire 2 is 0.18 or more and 0.36 or less. E2 / E1×D is preferably 0.20 or more, more preferably 0.24 or more, even more preferably 0.26 or more, particularly preferably 0.30 or more, and is preferably 0.35 or less, more preferably 0.34 or less, even more preferably 0.33 or less. Within the above range, the effect can be suitably obtained.

[0067] The mechanism by which greater effectiveness is obtained by adjusting E2 / E1×D within the above range is not clear, but is presumed to be as follows. When E2 / E1×D is in the above range, the ends of the shoulder portion are appropriately sparse and the bending rigidity of the filament is appropriate, so that the strain generated during running is dispersed and heat generation is suppressed, improving durability. In other words, if E2 / E1×D is small, the shoulder portion moves too much and the amount of heat generated increases, while if it is too large, the shoulder portion cannot move well and strain is concentrated in the rubber. Therefore, it is presumed that heat generation is suppressed as described above and durability is improved.

[0068] From the viewpoint of obtaining a greater effect, it is desirable that the product (E2 / E1×Sc) of the ratio (E2 / E1) of E2 (piece / 10 mm) to E1 (piece / 10 mm) and Sc (mm) of tire 2 is 0.16 or more and 0.40 or less. E2 / E1×Sc is preferably 0.20 or more, more preferably 0.24 or more, even more preferably 0.28 or more, particularly preferably 0.31 or more, and is preferably 0.38 or less, more preferably 0.36 or less, even more preferably 0.34 or less. Within the above ranges, the effect can be suitably obtained.

[0069] The mechanism by which greater effectiveness can be obtained by adjusting E2 / E1×Sc within the above range is not clear, but is presumed to be as follows. When E2 / E1×Sc is within the above range, it is believed that the stress difference between the E1 region and the E2 region is small, and durability can be improved. Specifically, when the end difference between E1 and E2 is large (E1 is extremely dense or E2 is extremely sparse) and Sc (BB gauge) is small, when the shear stress generated in the E1 region is transmitted to the E2 region, it is believed that the E2 region cannot absorb it, leading to cord breakage and destruction of the rubber layer. Conversely, when the end difference between E1 and E2 is small and the BB gauge is large, the radial bending rigidity of the two breaker packages as a whole increases, leading to deterioration of the ground contact shape, the whole does not contact the ground flexibly, and the ground contact of the shoulder part deteriorates. And, it is believed that the deterioration of the ground contact of the shoulder part causes bending distortion to concentrate on the steel cord, leading to cord breakage. Therefore, it is presumed that the stress difference is small as described above, and durability is improved.

[0070] The band layer (belt reinforcing layer) 18 in Fig. 1 is located radially outward of the belt layer 16. In the tire 2 in Fig. 1, the band layer 18 has a width equal to that of the belt layer 16 in the axial direction. The band layer 18 may have a width larger than that of the belt layer 16.

[0071] The band layer 18 is preferably made of a cord and a topping rubber (coating rubber). The cord is wound in a spiral shape. This band layer 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is preferably 5° or less, more preferably 2° or less. Since the belt layer 16 is restrained by the cord, lifting of the belt layer 16 is suppressed.

[0072] In the tire 2, the band layer 18 can increase the restraining property of each belt ply 17, and can increase the durability performance during high-speed running, and can also impart good ride comfort performance.

[0073] One embodiment of the band layer 18 includes an organic fiber cord 18A and a reinforcing rubber 18B (a band layer coating rubber composition) that coats the organic fiber cord 18A. Generally, the organic fiber cord is subjected to a dipping treatment to improve adhesion to the rubber.

[0074] Examples of organic fibers constituting the organic fiber cord 18A include polyester, polyamide, and cellulose. These may be synthetic fibers or fibers derived from biomass. From the viewpoint of life cycle assessment, it is preferable that the fibers are derived from recycled or regenerated materials. These fibers may be formed from a single component of synthetic fiber, biomass fiber, or recycled / regenerated fiber, or may be a hybrid cord twisted together with these fibers, a cord using a multifilament made up of each filament, or a cord having a chemical structure in which each component is chemically bonded.

[0075] Examples of polyester cords include polyethylene terephthalate (PET) cords, polyethylene naphthalate (PEN) cords, and polyethylene furanoate (PEF) cords. Compared with other polyester cords, PEF cords may be used because they have excellent air permeability resistance and are easy to maintain air pressure inside the tire. In addition, a hybrid cord may be used in which a part of the polyester cord is replaced with a cord made of other organic fiber such as polyamide fiber.

[0076] When the polyester cord is a biomass-derived polyester cord, for example, a biomass PET cord using terephthalic acid or ethylene glycol derived from biomass, or a biomass PEF cord using furandicarboxylic acid derived from biomass can be suitably used.

[0077] Biomass polyester cord can be obtained, for example, from bioethanol, furfurals, carenes, cymenes, terpenes, etc., or from compounds derived from various animals and plants, or from biomass terephthalic acid or biomass ethylene glycol produced by direct fermentation from microorganisms, etc.

[0078] Examples of the polyamide cord include aliphatic polyamides, semi-aromatic polyamides, and fully aromatic polyamides.

[0079] Aliphatic polyamides are polyamides having a skeleton in which linear carbon chains are linked by amide bonds, and examples thereof include nylon 4 (PA4), nylon 410 (PA410), nylon 6 (PA6), nylon 66 (PA66), nylon 610 (PA610), nylon 1010 (PA1010), nylon 1012 (PA1012), nylon 11 (PA11), etc. Among these, nylon 4, nylon 410, nylon 610, nylon 10, nylon 1010, nylon 11, etc. can be mentioned from the viewpoint of being easily obtainable partially or completely from biomass-derived materials.

[0080] Nylon 6 and nylon 66 may be produced by ring-opening polymerization of caprolactam derived from conventional chemical synthesis, or by condensation polymerization of hexamethylenediamine and adipic acid, or may be produced by using biocaprolactam, bioadipic acid, or biohexamethylenediamine produced from bio-derived cyclohexane as a starting material, and used to produce nylon 6 or nylon 66. The bio-based materials may also be obtained from sugars such as glucose. These nylon 6 and nylon 66 are considered to have the same strength as those that have been used conventionally.

[0081] A representative example of nylon 4 is one made from 2-pyrrolidone, which is obtained by converting glutamic acid derived from biofermentation into γ-aminobutyric acid, but this is not limited to this. Nylon 4 has good thermal and mechanical stability and is easy to design the polymer structure, so it can be used favorably as it contributes to improving the performance and strength of tires.

[0082] Nylon 410, nylon 610, nylon 1010, nylon 1012, nylon 11, etc. can be obtained from raw materials such as ricinoleic acid obtained from castor oil (castor bean). Specifically, nylon 410, nylon 610, and nylon 1010 can be obtained by condensation polymerization of sebacic acid and dodecanedioic acid obtained from castor oil with any diamine compound, and nylon 11 can be obtained by condensation polymerization of 11-aminoundecanoic acid obtained from castor oil.

[0083] Semi-aromatic polyamides are polyamides having an aromatic ring structure in part of the molecular chain, and examples thereof include nylon 4T (PA4T), nylon 6T (PA6T), and nylon 10T (PA10T).

[0084] Nylon 4T, Nylon 6T, and Nylon 10T can be obtained by using terephthalic acid as a dicarboxylic acid and carrying out condensation polymerization with a diamine compound having an arbitrary number of carbon atoms. In this case, it is also possible to obtain these nylon materials using the above-mentioned terephthalic acid derived from biomass. These nylons have a rigid cyclic structure in the molecular chain, and therefore excel in terms of heat resistance, etc.

[0085] Further, examples of the aliphatic polyamides and semi-aromatic polyamides mentioned above include polyamide 5X (X is the number of carbon atoms derived from a dicarboxylic acid, and T represents an integer or terephthalic acid) obtained by polymerizing 1,5-pentanediamine derived from lysine with dicarboxylic acids.

[0086] The fully aromatic polyamide is a polyamide having a skeleton in which aromatic rings are linked by amide bonds, and examples thereof include polyparaphenylene terephthalamide, etc. As with the above-mentioned aliphatic polyamides and semi-aromatic polyamides, the fully aromatic polyamide may also be obtained by bonding terephthalic acid derived from biomass with phenylenediamine.

[0087] Examples of cellulose fibers include rayon, polynosic, cupra, acetate, lyocell, modal, etc., which are produced from plant materials such as wood pulp. These cellulose fibers are preferred because they are not only made from carbon-neutral raw materials, but also have excellent environmental performance, such as being biodegradable and not emitting harmful gases even when incinerated after use. Among the above, rayon, polynosic, and lyocell are particularly preferred in terms of the balance between process efficiency, environmental friendliness, and mechanical strength.

[0088] Furthermore, the cord may be a recycled cord, whether synthetic or derived from biomass, obtained by collecting and refining used items such as beverage bottles and clothing, and then re-spinning the resulting material.

[0089] The cord may be formed by twisting one or more filaments together. For example, two 1100 dtex multifilaments (in other words, 1100 / 2 dtex) are twisted 48 times / 10 cm, and then two of these first twisted cords are twisted together and twisted the same number of times in the opposite or same direction as the first twist, or two 1670 dtex multifilaments (in other words, 1670 / 2 dtex) are twisted 40 times / 10 cm, and then two of these first twisted cords are twisted together and twisted.

[0090] In order to ensure good adhesion to the coating layer, the cord is preferably treated in advance with an adhesive layer. Any known adhesive layer can be used, including, for example, a treatment with resorcinol-formalin-rubber latex (RFL), an epoxy treatment with an adhesive composition containing sorbitol polyglycidyl ether and blocked isocyanate, and then an RFL treatment, or an adhesive composition containing a halohydrin compound, a blocked isocyanate compound, and rubber latex.

[0091] Resorcinol-formaldehyde-rubber latex (RFL) is, for example, an adhesive composition containing natural rubber and / or synthetic rubber latex and a co-condensation product of phenol-formaldehyde and resorcinol, as described in JP-A-48-11335. Such an adhesive composition can be produced, for example, by a production method including a step of condensing phenol and formaldehyde in the presence of an alkaline catalyst, a step of copolymerizing an aqueous phenol-formaldehyde resin solution with resorcinol, and a step of mixing the resulting phenol-formaldehyde-resorcinol resin solution with latex rubber.

[0092] Examples of the synthetic rubber latex include butadiene polymer latex, styrene / butadiene copolymer latex, isoprene polymer latex, butadiene / acrylonitrile copolymer latex, butadiene / vinylpyridine polymer latex, and butadiene / vinylpyridine / styrene copolymer latex.

[0093] The adhesive layer made of resorcinol-formaldehyde-rubber latex (RFL) can be formed by applying an RFL adhesive (such as by immersing the cord in an RFL liquid (DIP: dipping)). The RFL adhesive is usually applied after the fiber cord is obtained by twisting, but it may be applied before or during the twisting.

[0094] The composition of the RFL adhesive is not particularly limited and may be appropriately selected. Among them, a composition containing 0.1 to 10 mass % of resorcinol, 0.1 to 10 mass % of formalin, and 1 to 28 mass % of latex is preferable, and a composition containing 0.5 to 3 mass % of resorcinol, 0.5 to 3 mass % of formalin, and 10 to 25 mass % of latex is more preferable.

[0095] An example of a heating method for the heat treatment is a method in which the cord to which the RFL adhesive composition is attached is dried at 100 to 250° C. for 1 to 5 minutes, and then further heat-treated at 150 to 250° C. for 1 to 5 minutes. The heat treatment conditions after the drying treatment are preferably 180 to 240° C. for 1 to 2 minutes.

[0096] The adhesive composition containing the sorbitol polyglycidyl ether and the blocked isocyanate is not particularly limited as long as it is a composition containing a sorbitol polyglycidyl ether and a blocked isocyanate. Among them, a composition containing an epoxy compound which is a sorbitol polyglycidyl ether and has a chlorine content of 9.6 mass% or less, and a blocked isocyanate is preferable.

[0097] Examples of sorbitol polyglycidyl ether include sorbitol diglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, sorbitol pentaglycidyl ether, sorbitol hexaglycidyl ether, and mixtures thereof, and may include sorbitol monoglycidyl ether. Sorbitol polyglycidyl ether has many epoxy groups in one molecule and can form a highly crosslinked structure.

[0098] The chlorine content of the sorbitol polyglycidyl ether is preferably 9.6% by mass or less, more preferably 9.5% by mass or less, further preferably 9.4% by mass or less, and particularly preferably 9.3% by mass or less. The lower limit of the chlorine content is not particularly limited, and is, for example, 1% by mass or more. In the present invention, the chlorine content of the sorbitol polyglycidyl ether can be determined by the method described in JIS K 7243-3, for example.

[0099] The chlorine content of the sorbitol polyglycidyl ether can be reduced by, for example, reducing the amount of epichlorohydrin used in synthesizing the epoxy compound.

[0100] A blocked isocyanate is a compound that is produced by the reaction of an isocyanate compound with a blocking agent and is temporarily inactivated by a group derived from the blocking agent. When heated at a predetermined temperature, the group derived from the blocking agent dissociates to produce an isocyanate group.

[0101] The isocyanate compound may, for example, have two or more isocyanate groups in the molecule. Examples of diisocyanates having two isocyanate groups include hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, tolylene diisocyanate, trimethylhexamethylene diisocyanate, metaphenylene diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, diphenylpropane diisocyanate, biphenyl diisocyanate, and their isomers, alkyl substitution products, halides, and hydrogenated products of benzene rings. In addition, triisocyanates having three isocyanate groups, tetraisocyanates having four isocyanate groups, and polymethylene polyphenyl polyisocyanate can be used. These isocyanate compounds can be used alone or in combination of two or more. Among these, tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and polymethylene polyphenyl polyisocyanate are preferred.

[0102] Examples of blocking agents include lactam-based agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; phenol-based agents such as phenol, cresol, resorcinol, and xylenol; alcohol-based agents such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; oxime-based agents such as formamidoxime, acetaldoxime, acetoxime, methylethylketoxime, diacetylmonoxime, benzophenoneoxime, and cyclohexanoneoxime; and active methylene-based agents such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone. Among these, lactam-based, phenol-based, and oxime-based blocking agents are preferred.

[0103] In the adhesive composition containing the sorbitol polyglycidyl ether and the blocked isocyanate, the content of the blocked isocyanate is preferably 50 parts by mass or more, more preferably 200 parts by mass or more, relative to 100 parts by mass of the sorbitol polyglycidyl ether. The upper limit is preferably 500 parts by mass or less, more preferably 400 parts by mass or less.

[0104] The adhesive composition containing sorbitol polyglycidyl ether and blocked isocyanate may contain the following optional components as necessary, such as an epoxy compound other than sorbitol polyglycidyl ether, a resin copolymerizable with sorbitol polyglycidyl ether, a curing agent other than blocked isocyanate, an organic thickener, an antioxidant, a light stabilizer, an adhesion improver, a reinforcing agent, a softener, a colorant, a leveling agent, a flame retardant, and an antistatic agent.

[0105] Examples of epoxy compounds other than sorbitol polyglycidyl ether include glycidyl ethers such as ethylene glycol glycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, and brominated bisphenol A diglycidyl ether; glycidyl esters such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; triglycidyl ethers such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; Examples of suitable glycidyl amines include glycidyl isocyanurate, glycidyl hindantoin, tetraglycidyl diaminodiphenylmethane, triglycidyl para-aminophenol, triglycidyl meta-aminophenol, diglycidyl aniline, diglycidyl toluidine, tetraglycidyl meta-xylylenediamine, diglycidyl tribromoaniline, and tetraglycidyl bisaminomethylcyclohexane; and alicyclic or aliphatic epoxides such as 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil.

[0106] The treatment with the adhesive composition containing the above-mentioned sorbitol polyglycidyl ether and blocked isocyanate includes a treatment carried out for adhering various components contained in the RFL to the cord, and a treatment including a subsequent heat treatment if necessary.

[0107] The adhesion method may be any method such as application using a roller, spraying from a nozzle, immersion in a bath liquid (adhesive composition), etc. From the viewpoints of uniform adhesion and removal of excess adhesive, adhesion by immersion is preferred.

[0108] In order to adjust the amount of adhesion to the cord, further means such as squeezing with a pressure roller, scraping with a scraper or the like, blowing off with air blowing, suction, beating with a beater, etc. may be employed.

[0109] The amount of adhesion to the cord is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and is preferably 3.0% by mass or less, more preferably 2.5% by mass or less. The amount of the RFL adhesive applied to the cord is the amount of solid content in the RFL adhesive applied per 100 parts by mass of the cord.

[0110] The total solids concentration of the adhesive composition containing the above-mentioned sorbitol polyglycidyl ether and blocked isocyanate is preferably 0.9 mass% or more, more preferably 14 mass% or more, and is preferably 29 mass% or less, more preferably 23 mass% or less.

[0111] The adhesive composition containing the sorbitol polyglycidyl ether and the blocked isocyanate may contain, in addition to resorcin, formalin, and rubber latex, vulcanization regulators, zinc oxide, antioxidants, defoamers, and the like.

[0112] An example of a heating method for the heat treatment is to dry the reinforcing material 16 to which the RFL adhesive composition is attached at 100 to 250° C. for 1 to 5 minutes, and then to further heat treat it at 150 to 250° C. for 1 to 5 minutes. The conditions for the heat treatment after the drying treatment are desirably 180 to 240° C. for 1 to 2 minutes.

[0113] The adhesive composition containing the above-mentioned halohydrin compound, blocked isocyanate compound, and rubber latex is not particularly limited as long as it contains these components, but an adhesive composition containing a halohydrin compound, a blocked isocyanate compound, and rubber latex, but not containing resorcinol and formaldehyde, is preferable.

[0114] Examples of the halohydrin compound include compounds obtained by reacting a polyol compound with an epihalohydrin compound (halohydrin ether). A polyol compound is a compound having two or more hydroxyl groups in the molecule, and examples thereof include glycols such as ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol, hydroxyl acids such as erythritol, xylitol, sorbitol, and tartaric acid, glyceric acid, glycerin, diglycerin, polyglycerin, trimethylolpropane, trimethylolethane, and pentaerythritol. Examples of the epihalohydrin compound include epichlorohydrin and epibromohydrin.

[0115] Examples of the halohydrin compound include a fluoroalcohol compound, a chlorohydrin compound, a bromohydrin compound, an iodohydrin compound, etc. Among these, halogenated sorbitol and halogenated glycerol are preferred.

[0116] The halogen content in 100% by mass of the halohydrin compound is preferably from 5.0 to 15.0% by mass, more preferably from 7.0 to 13.0% by mass, and even more preferably from 9.0 to 12.0% by mass.

[0117] Examples of the blocked isocyanate compound include the same compounds as the blocked isocyanate described above. Examples of the rubber latex include the same rubber latex as the rubber latex described above.

[0118] The adhesive composition containing the halohydrin compound, the blocked isocyanate compound, and the rubber latex preferably contains 10.0 to 30.0 parts by mass of the halohydrin compound, 10.0 to 30.0 parts by mass of the blocked isocyanate compound, and 80.0 to 240.0 parts by mass of the rubber latex, and does not contain resorcinol or formaldehyde.

[0119] An adhesive layer made of an adhesive composition containing the halohydrin compound, a blocked isocyanate compound, and a rubber latex is formed on the surface of the cord using the adhesive composition. The adhesive layer is formed by, for example, dipping, brushing, casting, spraying, roll coating, knife coating, etc., but is not limited thereto.

[0120] FIG. 5 is an enlarged cross-sectional view showing the vicinity of the tread portion 4 of the tire 2 in FIG. 1, in which Tt indicates the thickness of the tread portion 4, and Tb indicates the thickness Tb of each belt layer 16 of the inner layer 38 and the outer layer 40.

[0121] From the viewpoint of obtaining a greater effect, it is preferable that the tire 2 further includes a tread portion 4, and that the product Tt×E1 of the thickness Tt (mm) of the tread portion 4 and the above-mentioned E1 is 100 or more and 120 or less. Tt×E1 is preferably 90 or more, more preferably 95 or more, and even more preferably 100 or more, and is preferably 117 or less, more preferably 115 or less, and even more preferably 112 or less.

[0122] The mechanism by which adjusting Tt×E1 to the above range, particularly to 100 to 120, provides a greater effect is not clear; however, it is believed that adjusting the value of Tt×E1 to a predetermined value or more suppresses deformation of the tread crown portion, making it easier to prevent damage originating from the crown portion. On the other hand, if E1 is large, the tread rubber is compressed between the belt layer and the road surface and becomes easily deformed, which increases heat generation, and if Tt is large, it is thought that heat accumulation is easily generated in the tread portion. Therefore, it is thought that by adjusting Tt×E1 to a specified value or less, heat accumulation and heat generation can be suppressed, which makes it easier to improve durability performance. Therefore, it is presumed that durability is improved by adjusting Tt×E1 to the above range.

[0123] The thickness Tt of the tread portion 4 is preferably 7.6 mm or more, more preferably 9.0 mm or more, and even more preferably 10.0 mm or more, and is preferably 15.0 mm or less, more preferably 14.0 mm or less, and even more preferably 13.0 mm or less. Within the above ranges, the effect tends to be better obtained.

[0124] In the present invention, the "thickness of the tread portion" means the thickness of the tread portion on the tire equatorial plane in the radial cross section of the tire. The thickness Tt of the tread portion is a value measured along the normal of the tread surface on the tire equatorial plane, and is the distance from the tread surface to the interface of the reinforcement layer containing steel, textile, or other fiber material such as a belt layer, a carcass layer, or a belt reinforcing layer on the tire's outermost surface side. In addition, when a groove is present on the tire equatorial plane, it is a straight-line distance from a plane formed by a straight line connecting the ends of the groove on the tire's radial outermost surface side. In the case of the tire 2 of FIG. 4, the thickness Tt of the tread portion is a straight-line distance from a plane formed by a straight line connecting the ends of the groove 26 corresponding to the tread surface on the tire equatorial plane L on the tire's outermost surface side in the radial direction to the tire's outer surface in the radial direction.

[0125] FIG. 5 is an enlarged cross-sectional view showing the vicinity of the tread portion 4 of the tire 2, and Tb indicates the thickness of each belt ply constituting the belt layer 16. Tb indicates the thickness of each of the inner and outer belt layers 38 and 40. The thickness Tb of each belt ply is preferably 0.50 mm or more, more preferably 0.70 mm or more, and even more preferably 0.72 mm or more, and is preferably 1.50 mm or less, more preferably 1.20 mm or less, and even more preferably 1.00 mm or less. Within the above ranges, the effect tends to be better obtained.

[0126] In the present invention, the "belt ply thickness" refers to the thickness of each belt ply layer including the steel monofilament and its covering rubber in a cross section cut along a plane including the tire rotation axis, and refers to the average value of the belt ply thickness in the normal direction at each point on the surface of each belt ply layer. In the case of the belt layer 16 consisting of two layers, the inner layer 38 and the outer layer 40 in Fig. 2, the thickness of the inner layer 38 is the average value of the thickness in the normal direction at each point on the inner layer surface, and the thickness of the outer layer 40 is the average value of the thickness in the normal direction at each point on the outer layer surface.

[0127] The belt layer 16 in FIG. 1 is located radially inward of the tread portion 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. In the tire 2 in FIG. 1, the belt layer 16 is composed of an inner layer 38 and an outer layer 40. As is clear from FIG. 1, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40 in the axial direction. In this tire 2, the axial width of the belt layer 16 is preferably 0.6 times or more and 0.9 times or less of the cross-sectional width of the tire 2.

[0128] In the tire 2 of FIG. 1, the inner liner 20 is located inside the carcass 14. The inner liner 20 is bonded to the inner surface of the carcass 14. A typical base rubber of the inner liner 20 is butyl rubber or halogenated butyl rubber. The inner liner 20 holds the internal pressure of the tire 2.

[0129] Each chafer 22 is located adjacent to a bead 12. In this embodiment, the chafer 22 is preferably made of fabric with rubber impregnated into the fabric. The chafer 22 may be integral with the clinch 10.

[0130] In this tire 2, the tread portion 4 has main grooves 42 as the grooves 26. As shown in FIG. 1, a plurality of main grooves 42, specifically three main grooves 42, are formed in the tread portion 4. These main grooves 42 are arranged at intervals in the axial direction. In the tread portion 4, four ribs 44 extending in the circumferential direction are formed by forming the three main grooves 42. In other words, the main grooves 42 are formed between the ribs 44.

[0131] Each of the main grooves 42 extends in the circumferential direction. The main grooves 42 are continuous in the circumferential direction without interruption. The main grooves 42 facilitate the drainage of water present between the road surface and the tire 2, for example, in rainy weather. Therefore, even if the road surface is wet, the tire 2 can make sufficient contact with the road surface.

[0132] In the tire 2, each rubber layer (such as the cap layer 30 and the base layer 28 in FIG. 1) constituting the tread portion 4 (such as a single-layer tread, a two-layer tread, or a tread portion having a structure of three or more layers) is made of a rubber composition for the tread. Also, the belt layer 16 (such as the inner layer 38 and the outer layer 40) includes a belt cord 17A and a topping rubber 17B (coating rubber) that coats the belt cord 17A, and the coating rubber is made of a coating rubber composition for the belt layer.

[0133] Unless otherwise specified, the materials that can be used in the following rubber composition are common to both the tread portion (rubber composition for tread) and the covering rubber of the belt layer (covering rubber composition for belt layer).

[0134] The rubber composition for the tread and the coating rubber composition for the belt layer each contain a rubber component. The rubber component is a component that contributes to crosslinking, and is generally a polymer with a weight average molecular weight (Mw) of 10,000 or more that is not extracted with acetone. The rubber component is in a solid state at room temperature (25°C).

[0135] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be better obtained.

[0136] In this specification, the weight average molecular weight (Mw) can be determined by converting it into standard polystyrene based on the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0137] As the rubber component usable in the rubber composition for tread and the rubber composition for covering the belt layer, for example, diene rubber can be used. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Examples also include butyl rubber and fluororubber. These may be used alone or in combination of two or more. Among them, in the rubber composition for tread, isoprene rubber, BR, and SBR are preferred from the viewpoint of obtaining a better effect, and BR and SBR are more preferred. In addition, in the rubber composition for covering the belt layer, isoprene rubber, BR, and SBR are preferred from the viewpoint of obtaining a better effect, and isoprene rubber is more preferred. These rubber components may be modified or hydrogenated as described below, and extended rubbers extended with oil, resin, liquid rubber components, etc. may also be used.

[0138] The diene rubber may be a non-modified diene rubber or a modified diene rubber. The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. Examples of the modified diene rubber include terminal-modified diene rubber (terminal-modified diene rubber having the functional group at the terminal) in which at least one terminal of the diene rubber has been modified with a compound (modifier) ​​having the functional group, main-chain modified diene rubber having the functional group in the main chain, main-chain terminal-modified diene rubber having the functional group in the main chain and at least one terminal (for example, main-chain terminal-modified diene rubber having the functional group in the main chain and at least one terminal modified with the modifier), and terminal-modified diene rubber modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0139] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of an amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0140] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS♯3, TSR20, and other rubber industry-standard rubbers. Examples of IR include IR2200 and other rubber industry-standard rubbers. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of 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.

[0141] When the rubber composition for tread contains an isoprene-based rubber, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less. When it is within the above range, the effect tends to be better obtained.

[0142] In the coating rubber composition for the belt layer, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, further preferably 75% by mass or more, particularly preferably 85% by mass or more, and may be 100% by mass. When it is within the above range, the effect tends to be better obtained.

[0143] The BR is not particularly limited, and for example, high cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more. In particular, the BR preferably contains high cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0144] In addition, either unmodified or modified BR can be used as the BR. Modified BR includes modified BR into which functional groups similar to those of modified diene rubbers have been introduced. In addition, hydrogenated butadiene polymer (hydrogenated BR) can also be used as the BR.

[0145] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0146] In the rubber composition for treads, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

[0147] When the belt layer coating rubber composition contains BR, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

[0148] 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. These may be used alone or in combination of two or more kinds.

[0149] The styrene content of the SBR is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. The styrene content is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. By keeping the styrene content within the above range, the handling stability during high-speed driving tends to be improved. In this specification, the styrene content is 1 It can be measured by H-NMR measurement.

[0150] The vinyl bond content of SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The vinyl bond content is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. By keeping it within the above range, the handling stability during high-speed driving tends to be improved. In this specification, the vinyl bond amount (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopy.

[0151] Both unmodified and modified SBR can be used. Modified SBR includes modified SBR with the same functional groups as modified diene rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0152] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., and the like can be used.

[0153] In the rubber composition for treads, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more. The upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. Within the above range, the effect tends to be better obtained.

[0154] When the belt layer coating rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

[0155] The rubber composition for the tread and the covering rubber composition for the belt layer may contain a filler. The filler is not particularly limited, and any material known in the rubber field can be used. Examples of the filler include inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, biochar, and poorly dispersible fillers.

[0156] In the rubber composition for treads, the total content of the filler (total amount of fillers such as silica, carbon black, etc.) is preferably 30 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 65 parts by mass or more, and particularly preferably 80 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0157] In the coating rubber composition for the belt layer, the total content of the filler (total amount of fillers such as silica, carbon black, etc.) is preferably 10 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 55 parts by mass or more, and particularly preferably 60 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0158] Among the fillers, carbon-derived fillers (carbon-containing fillers) such as carbon black and silica are preferred.

[0159] Carbon black usable in the rubber composition for tread and the coating rubber composition for belt layer is not particularly limited, but may be N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. These may be used alone or in combination of two or more. In addition to conventional carbon black made from mineral oils, etc., carbon black made from biomass materials such as lignin may be used. Recycled carbon black obtained by decomposing rubber products containing carbon black, such as tires, plastic products, etc., may be appropriately substituted for the above carbon black in an equal amount.

[0160] In the rubber composition for tread, the nitrogen adsorption specific surface area (N2SA) of carbon black is 50m 2 / g or more is preferable, and 70m 2 / g or more is more preferable, and 90m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 120m 2 Within the above range, there is a tendency that the effect is better obtained. The nitrogen adsorption specific surface area of ​​carbon black is determined in accordance with JIS K6217-2:2001.

[0161] In the belt layer coating rubber composition, the nitrogen adsorption specific surface area (N2SA) of carbon black is 10 m 2 / g or more is preferable, and 20m 2 / g or more is more preferable, and 25m 2 / g or more is more preferable. 2 / g or less is preferable, and 60m 2 / g or less is more preferable, and 45m 2 / g or less is more preferable, and 35m 2Within the above range, there is a tendency that the effect is more favorable.

[0162] In the rubber composition for treads, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0163] In the coating rubber composition for the belt layer, the carbon black content is preferably 10 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 55 parts by mass or more, and particularly preferably 60 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0164] In particular, the belt layer coating rubber composition has a nitrogen adsorption specific surface area of ​​45 m 2 The carbon black content of 0.1 to 1.0 parts by mass / g or less is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0165] In the coating rubber composition for the belt layer, a predetermined amount of carbon black having an N2SA in the above range is blended, particularly N2SA45m 2The mechanism by which greater effects are obtained by blending 5 to 60 parts by mass of carbon black with a particle size of 0.1 to 1.0 μm / g or less is not clear; however, it is presumed that the use of large particle size carbon black in the belt coating layer makes it easier to reduce the heat generation in the belt layer and to improve the responsiveness of the belt layer, thereby improving the handling stability during high-speed driving.

[0166] Examples of silica that can be used in the rubber composition for tread and the coating rubber composition for belt layer include dry process silica (anhydrous silica) and wet process silica (hydrated silica). Among them, wet process silica is preferred because it has a large number of silanol groups. Commercially available products include products from Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama. These may be used alone or in combination of two or more. In addition to these silicas, silica made from biomass materials such as rice husks may also be used.

[0167] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 180m 2 / g or more, most preferably 190m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 Within the above range, there is a tendency for the effect to be better obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0168] In the rubber composition for treads, the content of silica is preferably 20 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 65 parts by mass or more, and particularly preferably 75 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0169] The mechanism by which a greater effect is obtained by adjusting the amount of silica to the above range, particularly 50 to 100 parts by mass, is not clear; however, it is presumed that the use of a predetermined amount of silica makes it easier to lower tan δ and improves responsiveness, thereby improving steering stability during high-speed driving.

[0170] When the coating rubber composition for the belt reinforcing layer contains silica, the content of silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0171] When the rubber composition for the tread and the coating rubber composition for the belt layer contain silica, it is preferable that they further contain a silane coupling agent. The silane coupling agent is not particularly limited, and those known in the rubber field can be used. For example, 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, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N, Examples of such silylsilanes include sulfide-based silylsilanes such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silylsilanes such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based silylsilanes such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silylsilanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silylsilanes such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silylsilanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silylsilanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those manufactured by Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0172] In the rubber composition for tread and the rubber composition for belt layer, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, based on 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0173] Examples of the poorly dispersible filler include microfibrillated vegetable fibers, short fiber cellulose, gel compounds, etc. Among these, microfibrillated vegetable fibers are preferred.

[0174] The microfibrillated plant fiber is preferably cellulose microfibril, since it has good reinforcing properties. The cellulose microfibril is not particularly limited as long as it is derived from a natural product, and examples thereof include those derived from resource biomass such as fruits, grains, and root vegetables, wood, bamboo, hemp, jute, and kenaf, and pulp, paper, cloth, agricultural waste, waste biomass such as food waste and sewage sludge obtained from these as raw materials, unused biomass such as rice straw, wheat straw, and thinned wood, as well as cellulose produced by sea squirts, acetic acid bacteria, etc. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0175] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, more typically cellulose fibers having a microstructure formed by the aggregation of cellulose molecules and an average fiber diameter of 500 nm or less. Typical cellulose microfibrils are formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

[0176] In the rubber composition for tread and the coating rubber composition for belt layer, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0177] A plasticizer may be blended into the tread rubber composition and the belt layer covering rubber composition. A plasticizer is a material that imparts plasticity to a rubber component. Examples of the plasticizer include liquid plasticizers (plasticizers that are in a liquid state at room temperature (25°C)) and resins (resins that are in a solid state at room temperature (25°C)).

[0178] In the rubber composition for treads, the content of the plasticizer (total amount of the plasticizer) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. Within the above range, the effect tends to be better obtained. In addition, when the above-mentioned extension rubber is used, the amount of the extension component used in the extension rubber is included in the content of the plasticizer.

[0179] In the belt layer coating rubber composition, the content of the plasticizer (total amount of the plasticizer) is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and may be 0 parts by mass, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better. In addition, when the above-mentioned extension rubber is used, the amount of the extension component used in the extension rubber is included in the content of the plasticizer.

[0180] Liquid plasticizers (plasticizers in a liquid state at room temperature (25°C)) that can be used in the rubber composition for the tread and the coating rubber composition for the belt layer are not particularly limited, and examples thereof include oils, liquid polymers (liquid resins, liquid diene-based polymers, etc.), etc. These may be used alone or in combination of two or more kinds.

[0181] In the rubber composition for tread, the content of the liquid plasticizer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above range, the effect tends to be better obtained. The content of the oil is also preferably within the same range.

[0182] In the coating rubber composition for the belt layer, the content of the liquid plasticizer is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and may be 0 parts by mass, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better. When the content is within the above range, the effect tends to be better. The content of the oil is also preferably within the same range.

[0183] Examples of the oil include process oil, vegetable oil, and mixtures thereof. Examples of the process oil include paraffin-based process oil, aroma-based process oil, naphthene-based process oil, and the like, such as MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (treated Distillate Aromatic Extract), TRAE (treated Residual Aromatic Extract), and RAE (residual aromatic extract). Examples of the vegetable oil 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. As commercially available products, products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used. Among them, process oils (paraffin-based process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred. From the viewpoint of life cycle assessment, the above-mentioned oils may be lubricating oils used in rubber mixers and engines, or oils refined from waste edible oils used in restaurants.

[0184] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, acrylic resins, etc. Hydrogenated products of these resins can also be used.

[0185] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), liquid farnesene polymers, and liquid farnesene butadiene copolymers that are in a liquid state at 25°C. The ends or main chains of these may be modified with polar groups. Hydrogenated versions of these may also be used.

[0186] Examples of the resins (resins in a solid state at room temperature (25°C)) that can be used in the rubber composition for the tread and the coating rubber composition for the belt layer include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are in a solid state at room temperature (25°C). The resins may be hydrogenated. These may be used alone or in combination of two or more. Of these, aromatic vinyl polymers, petroleum resins, and terpene resins are preferred.

[0187] When the rubber composition for tread contains the above resin, the amount is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and may be 0 parts by mass, per 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be better. When the amount is within the above range, the effect tends to be better.

[0188] When the belt layer coating rubber composition contains the above resin, the amount is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and may be 0 parts by mass, based on 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be better. When the amount is within the above range, the effect tends to be better.

[0189] The softening point of the resin is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher. The upper limit is preferably 160° C. or lower, more preferably 130° C. or lower, and even more preferably 115° C. or lower. By keeping the softening point within the above range, the handling stability during high-speed driving tends to be improved. The softening point of the resin is the temperature at which the ball drops when the softening point is measured using a ring and ball softening point tester as specified in JIS K6220-1: 2001. The softening point of the resin is usually 50°C ± 5°C higher than the glass transition temperature of the resin.

[0190] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a structural unit. For example, it can be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically, it can be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, a copolymer of styrene and another monomer, etc.

[0191] The coumarone-indene resin is a resin containing coumarone and indene as main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0192] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0193] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0194] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Among these, those obtained by reacting with an acid catalyst (such as novolac-type phenolic resin) are preferred.

[0195] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0196] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, and hydrogenated versions of these resins. Of these, DCPD resin and hydrogenated DCPD resin are preferred.

[0197] The terpene resin is a polymer containing terpene as a structural unit. For example, polyterpene resin obtained by polymerizing a terpene compound, aromatic modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, etc. can be mentioned. Hydrogenated products of these can also be used.

[0198] The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives represented by the composition 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0199] Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, pinene / limonene resin, etc., which are made from the above-mentioned terpene compounds. Among them, pinene resin is preferable. Pinene resin usually contains both α-pinene and β-pinene, which are isomers, but depending on the components contained, it is classified into β-pinene resin mainly composed of β-pinene and α-pinene resin mainly composed of α-pinene.

[0200] Examples of the aromatic modified terpene resin include terpene phenol resins made from the above terpene compounds and phenolic compounds, and terpene styrene resins made from the above terpene compounds and styrene compounds. Terpene phenol styrene resins made from the above terpene compounds, phenolic compounds, and styrene compounds can also be used. Examples of the phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of the styrene compounds include styrene and α-methylstyrene.

[0201] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, such as a styrene-acrylic resin, can be used. Among them, a solventless carboxyl group-containing styrene-acrylic resin can be preferably used.

[0202] The solvent-free carboxyl group-containing styrene-acrylic resin is a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (methods described in U.S. Pat. No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, Toa Gosei Kenkyuu Nenpo TREND 2000 Vol. 3, p. 42-45, etc.) with minimal use of auxiliary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In this specification, (meth)acrylic means methacryl and acrylic.

[0203] Examples of the acrylic monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), (meth)acrylamide, (meth)acrylic acid derivatives such as (meth)acrylamide derivatives, etc. (Meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

[0204] Examples of the aromatic vinyl monomer component constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0205] As the monomer components constituting the acrylic resin, other monomer components may be used in addition to the (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

[0206] Examples of the plasticizer that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0207] The rubber composition for the tread and the rubber composition for covering the belt layer preferably contain an antioxidant from the viewpoints of crack resistance, ozone resistance, and the like.

[0208] The antiaging agent is not particularly limited, and examples thereof include naphthylamine-based antiaging agents such as phenyl-α-naphthylamine; diphenylamine-based antiaging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, Examples of the antioxidant include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymerized 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis, tris, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include, for example, products from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd.

[0209] In the rubber composition for tread and the coating rubber composition for belt layer, the content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0210] The rubber composition for the tread and the coating rubber composition for the belt layer preferably contain stearic acid. In the rubber composition for tread and the coating rubber composition for belt layer, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0211] As the stearic acid, any conventionally known product can be used, for example, products available from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0212] The rubber composition for the tread and the coating rubber composition for the belt layer preferably contain zinc oxide. In the rubber composition for tread and the coating rubber composition for belt layer, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 12.0 parts by mass or less, more preferably 11.0 parts by mass or less, and even more preferably 10.0 parts by mass or less.

[0213] As the zinc oxide, any known zinc oxide can be used, for example, products available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0214] Wax may be blended into the rubber composition for the tread and the rubber composition for covering the belt layer. In the rubber composition for tread and the coating rubber composition for belt layer, the wax content is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, and even more preferably 5.0 parts by mass or less.

[0215] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Also, synthetic waxes obtained by refining or chemically treating multiple waxes can be used. These waxes may be used alone or in combination of two or more kinds.

[0216] Examples of petroleum waxes include paraffin wax and microcrystalline wax. Examples of natural waxes are not particularly limited as long as they are derived from resources other than petroleum, and include, for example, vegetable waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal waxes such as beeswax, lanolin, and spermaceti; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Examples of commercially available products include products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0217] It is preferable to compound sulfur into the rubber composition for the tread and the rubber composition for covering the belt layer in order to form an appropriate amount of crosslinked chains in the polymer chains and to impart good performance.

[0218] In the rubber composition for tread and the coating rubber composition for belt layer, the content of sulfur is preferably 0.1 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.7 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 4.0 parts by mass or less.

[0219] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

[0220] The rubber composition for the tread and the coating rubber composition for the belt layer preferably contain a vulcanization accelerator. In the rubber composition for tread and the rubber composition for covering belt layer, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization speed and crosslink density, but is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.5 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 4.0 parts by mass or less.

[0221] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among them, sulfenamide-based, guanidine-based and benzothiazole-based vulcanization accelerators are preferred.

[0222] In addition to the above-mentioned components, the rubber composition for the tread and the rubber composition for the covering of the belt layer may contain compounding agents generally used in the tire industry, such as materials such as a mold release agent.

[0223] It is desirable that the above-mentioned rubber composition be used for at least one rubber layer constituting the tread portion 4, and it is desirable that the outermost rubber layer in the tire radial direction of the tread portion 4 (cap layer 30 in the example of Figure 1) be composed of the above-mentioned suitable rubber composition.

[0224] The belt layer coating rubber composition may also contain an organic acid cobalt, a thermosetting resin, and the like. Here, the thermosetting resin is a resin that undergoes a curing reaction when heated, and is a component that cannot be extracted with a solvent, unlike the resin contained in a plasticizer, so the two are distinguished from each other.

[0225] Examples of organic acid cobalt include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, boron 3 cobalt neodecanoate, and cobalt abithienate. Commercially available products include those from Dai-Nippon Ink and Chemicals, Inc. These may be used alone or in combination of two or more. Among these, cobalt stearate is preferred.

[0226] In the coating rubber composition for the belt layer, the content of the organic acid cobalt is preferably 0.1 parts by mass or more, and preferably 1.2 parts by mass or less, more preferably 0.8 parts by mass or less, and further preferably 0.5 parts by mass or less, calculated as elemental cobalt, per 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0227] As the thermosetting resin, a resorcinol condensate (resorcinol resin) or a phenolic resin can be suitably used. These may be used alone or in combination of two or more kinds.

[0228] As the resorcinol condensate, for example, a compound (resin) represented by the following formula can be used. [ka] (In the formula, n is an integer of 1 or more.)

[0229] The resorcinol condensate may be a modified resorcinol condensate. As the modified resorcinol condensate, for example, a compound (resin) represented by the following formula can be used. [ka] (In the formula, n is an integer of 1 or more, and R is an alkyl group.)

[0230] As commercially available resorcinol condensates, products from Taoka Chemical Co., Ltd., Indospec, etc. can be used.

[0231] The phenolic resin is obtained by reacting phenol with an aldehyde such as formaldehyde in the presence of an acid or alkali catalyst.

[0232] The phenolic resin may be modified with cashew oil, tall oil, rosin, etc. The modified phenolic resin is preferably a cashew oil modified phenolic resin. For example, the compound (resin) represented by the following formula can be used as the cashew oil modified phenolic resin. [ka] (In the formula, p is an integer of 1 to 9, and preferably 5 to 6.)

[0233] As commercially available phenolic resins, products from Sumitomo Bakelite Co., Ltd. and the like can be used.

[0234] In the coating rubber composition for the belt layer, the content of the thermosetting resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0235] In addition, the rubber composition constituting the other members than the tread portion 4 and the belt layer 16 may also use the above-mentioned materials by appropriately changing the compounding amount.

[0236] The rubber composition for the tread, the coating rubber composition for the belt layer, etc. can be produced by a known method. For example, the components are kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized.

[0237] As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step in which the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°C. Furthermore, the composition kneaded with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

[0238] Examples of tires to which the present invention can be applied include pneumatic tires and non-pneumatic tires, among which pneumatic tires are preferred. In particular, the present invention can be suitably used as summer tires (summer tires) and winter tires (studless tires, snow tires, studded tires, etc.). The tires can be used as passenger car tires, large passenger car tires, large SUV tires, heavy load tires such as trucks and buses, light truck tires, two-wheeled vehicle tires, racing tires (high performance tires), etc.

[0239] The tire can be manufactured by a normal method. For example, in the unvulcanized stage, a rubber composition for tread containing various materials is extruded to fit the shape of the tread portion, and a steel cord (steel monofilament) and a rubber composition for belt layer containing various materials for covering the steel cord are combined and extruded to fit the shape of the belt layer, and molded together with other tire components in a normal method on a tire building machine to form an unvulcanized tire. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

[0240] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified in various ways. EXAMPLES

[0241] Below, examples (embodiments) that are considered to be preferable for carrying out the present disclosure will be shown, but the scope of the present disclosure is not limited to the embodiments.

[0242] A pneumatic tire (test tire) for passenger cars having a size of 195 / 65R15 and having the basic structure shown in FIG. 1 is prototyped based on the specifications in Table 1. The common specifications of the test tires are as follows: Belt plies: 2 (2-layer belt layer) Angle of belt cord in each belt layer to tire circumferential direction: 20 degrees (cross) Belt cord in each belt layer: Single wire (steel monofilament)

[0243] The covering rubber of the inner layer and the covering rubber of the outer layer constituting the belt layer are both made of the rubber composition having the compounding shown in Table 1. Both the inner and outer layers have a thickness Tb as set forth in Table 1.

[0244] Assuming that the test tires had specifications changed according to Table 1, the results were calculated based on the following evaluation method, and are shown in Table 1. The reference comparative example is Comparative Example 2.

[0245] [Table 1]

[0246] <Durability> The test tire is measured using a drum testing machine under conditions of standard rim (6.0J), internal pressure (260kPa), load (4.56kN), and road temperature of 80°C, at a speed of 230km / h on the drum, and the running time until peeling damage occurs in the tread rubber is measured. The results are expressed as an index, with the standard comparative example being 100. The higher the index, the better the durability performance.

[0247] The materials for the tread compound (rubber composition for tread) in Table 1 are as follows. SBR: HPR840 manufactured by JSR Corporation (Tg: -65°C, styrene content: 10% by mass, vinyl content: 42% by mass) BR: BR150B (cis content 98% by mass) manufactured by Ube Industries, Ltd. Silica: Ultrasil VN3 (Evonik, N2SA175m 2 / g) Carbon black N220: Diablack N220 (manufactured by Mitsubishi Chemical Corporation, N2SA114m 2 / g) Oil: Diana Process Oil AH-24 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Silane coupling agent: Si69 (Evonik, bis(3-triethoxysilylpropyl)tetrasulfide) Antioxidant 6C: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant RD: Nocrac 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Wax: Ozoace 0355 (manufactured by Nippon Seiro Co., Ltd.) Stearic acid: NOF Corporation Zinc oxide: Three types of zinc oxide (manufactured by Hakusui Tech Co., Ltd.) Sulfur: Powdered sulfur (Tsurumi Chemical Co., Ltd.) Vulcanization accelerator CZ: Noccela CZ-G (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DZ: Noccela DZ (N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, DCBS) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0248] The materials of the coating rubber compounding for the belt layer (rubber composition for the coating rubber for the belt layer) in Table 1 are as follows. NR:TSR20 Carbon black N326: Diablack N326 (N2SA:80m) manufactured by Mitsubishi Chemical Corporation 2 / g) Oil: Diana Process Oil AH-24 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Thermosetting resin: Sumikanol 620 (modified resorcinol condensate, softening point: 100°C) manufactured by Taoka Chemical Co., Ltd. Stearic acid: NOF Corporation Cobalt stearate: Cost-F (cobalt content: 9.5% by mass) manufactured by Dainippon Ink and Chemicals, Inc. Antioxidant RD: Nocrac 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Zinc oxide: Three types of zinc oxide (manufactured by Hakusui Tech Co., Ltd.) Sulfur: Powdered sulfur (Tsurumi Chemical Co., Ltd.) Vulcanization accelerator DZ: Noccela DZ (N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, DCBS) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0249] The present invention (1) is a tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q that is 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90; In the tire, the tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more.

[0250] The present invention (2) is the tire according to the present invention (1), in which the diameter D of the steel monofilament is 0.25 to 0.42 mm.

[0251] The present invention (3) is the tire according to the present invention (1) or (2), wherein the distance Sc between the steel monofilaments at the tire equatorial plane in adjacent belt plies is 0.25 to 0.45 mm.

[0252] The present invention (4) further comprises a tread portion, The tire is any combination with any of the present inventions (1) to (3), in which the product Tt×E1 of the thickness Tt (mm) of the tread portion and E1 is 100 or more and 120 or less.

[0253] The present invention (5) is a tire in any combination with any of the present inventions (2) to (4), in which the product S×D of S (mm) and D (mm) is 0.22 or more and 0.58 or less.

[0254] The present invention (6) is a tire in any combination with any of the present inventions (3) to (5), in which the ratio S / Sc of S (mm) and Sc (mm) is 2.2 or more and 4.0 or less.

[0255] The present invention (7) is a tire in any combination with any of the present inventions (1) to (6), in which E1 (pieces / 10 mm) of the belt layer is 8.5 or more and 15.5 or less.

[0256] The present invention (8) is a tire in any combination with any of the present inventions (2) to (7), in which the product (E2 / E1×D) of the ratio (E2 / E1) of E2 (piece / 10 mm) to E1 (piece / 10 mm) and D (mm) is 0.18 or more and 0.36 or less.

[0257] The present invention (9) is a tire in any combination with any of the present inventions (3) to (7), in which the product (E2 / E1×Sc) of the ratio (E2 / E1) of E2 (pieces / 10 mm) to E1 (pieces / 10 mm) and Sc (mm) is 0.16 or more and 0.40 or less. [Explanation of symbols]

[0258] 2 Tires 4 Tread section 6 Sidewall 8 Wing 10. Clinch 12 Beads 14 Carcass 16 Belt Layer 17 Belt ply 17A Belt Cord 17A1 Outermost belt cord in the tire width direction in the first belt ply 17A2 The outermost belt cord in the second belt ply in the tire width direction 17A5 Belt cord installed on the tire equatorial plane in the first belt ply 17A6 Belt cord installed on the tire equatorial plane in the second belt ply 17B Topping rubber (coated rubber) 18 Band Layer 18A Organic Fiber Cord 18B Reinforcement rubber covering organic fiber cord 20 Inner Liner 22 Chafer 26 Groove 28 Base Layer 30 Cap Layer 32 Bead core 34 Bead Apex 36 Carcass ply 36a Main part 36b Folded part 38 Inner layer (first belt ply) 40 Outer layer (second belt ply) 42 Main groove 44 Ribs Tt Tread thickness Tb Thickness of each belt layer

Claims

1. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q that is 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90, A tire in which the tire radial distance S between the outermost steel filament in the tire width direction of a belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more.

2. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q that is 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is 0.85 or less, A tire in which the tire radial distance S between the outermost steel filament in the tire width direction of a belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more.

3. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q at a position corresponding to 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90, A tire in which the tire radial distance S between the outermost steel filament in the tire width direction of a belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.95 mm or more.

4. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q at a position corresponding to 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90, The tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more, The tire further comprises a tread portion, wherein a product Tt×E1 of a thickness Tt (mm) of the tread portion and E1 is 117 or less.

5. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q at a position corresponding to 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90, The tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more, The tire has a product S×D of S (mm) and the diameter D (mm) of the steel monofilament, which is 0.32 or more.

6. A tire having two or more belt layers, The belt layer includes a belt ply having steel monofilaments and a coated rubber, In the tire radial cross section, when the tire width direction outer end position of the belt ply having the widest tire axial width among the belt plies is defined as point P, a ratio (E2 / E1) of the number E1 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction in a region from the tire equatorial plane of the belt ply having the widest axial width in the tire to a point Q at a position corresponding to 80% of the tire axial distance L to the point P to the number E2 (pieces / 10 mm) of arranged steel monofilaments per 10 mm in the tire width direction from the point Q to the point P is less than 0.90, The tire radial distance S between the outermost steel filament in the tire width direction of the belt ply adjacent to the belt ply having the widest width in the tire axial direction and the steel filament of the belt ply having the widest width in the tire axial direction is 0.80 mm or more, A tire in which E1 (pieces / 10 mm) of a belt layer is 15.5 or less.

7. 7. The tire according to claim 1, 2, 3, 4, 5 or 6, wherein the diameter D of the steel monofilament is 0.25 to 0.42 mm.

8. 7. The tire according to claim 1, wherein the distance Sc between the steel monofilaments at the tire equatorial plane in adjacent belt plies is 0.25 to 0.45 mm.

9. It also has a tread section, 7. The tire according to claim 1, 2, 3, 5 or 6, wherein a product Tt×E1 of the thickness Tt (mm) of the tread portion and the thickness E1 is 100 or greater and 120 or less.

10. A tire as described in claim 1, 2, 3, 4 or 6, wherein the diameter D of the steel monofilament is 0.25 to 0.42 mm, and the product S x D of S (mm) and D (mm) is 0.22 or more and 0.58 or less.

11. The tire according to claim 8, wherein a ratio S / Sc of the S (mm) and the Sc (mm) is equal to or greater than 2.2 and is equal to or less than 4.

0.

12. 6. The tire according to claim 1, 2, 3, 4 or 5, wherein E1 (pieces / 10 mm) of the belt layer is 8.5 or more and 15.5 or less.

13. The tire according to claim 7, wherein a product (E2 / E1×D) of a ratio (E2 / E1) of E2 (piece / 10 mm) to E1 (piece / 10 mm) and D (mm) is 0.18 or more and 0.36 or less.

14. The tire according to claim 8, wherein a product (E2 / E1×Sc) of a ratio (E2 / E1) of E2 (piece / 10 mm) to E1 (piece / 10 mm) and Sc (mm) is 0.16 or more and 0.40 or less.

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