Pneumatic tire and method for manufacturing the same

Abstract

To provide a pneumatic tire and a method for manufacturing the same that make it possible to reduce low-frequency road noise without deteriorating high-speed durability.SOLUTION: A pneumatic tire includes a tread portion 1 extending in a tire circumferential direction to form an annular shape, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed on inner sides of the sidewall portions 2 in a tire radial direction. The pneumatic tire has a specified mounting direction with respect to a vehicle. A sealant layer 20 is formed on a tire inner surface Ts of the tread portion 1. With a tire center line CL as a boundary, a cross-sectional area Sin [mm2] on a vehicle inner side and a cross-sectional area Sout [mm2] on a vehicle outer side in the sealant layer 20 are different from each other, and the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire in the tread portion, and a manufacturing method thereof. More specifically, the present invention relates to a pneumatic tire that can reduce low-frequency road noise without deteriorating high-speed durability, and a manufacturing method thereof. [Background technology]

[0002] Pneumatic tires with puncture sealing properties have been proposed that have a sealant layer made of an adhesive sealant on the inner surface of the tire tread (for example, Patent Document 1). In pneumatic tires with such a sealant layer, when a foreign object such as a nail penetrates the tread, the adhesive sealant clings to the foreign object and, as the foreign object falls off, is guided to the puncture hole, thereby providing a sealing effect.

[0003] In pneumatic tires equipped with such a sealant layer, the mass of the tread can be increased, which contributes to reducing low-frequency road noise. However, because the sealant is usually applied uniformly across the entire inner surface of the tread, heat dissipation tends to be poor across the entire inner surface of the tread. Furthermore, when a negative camber angle is set when the tire is mounted on a vehicle, the contact length of the shoulder on the inside of the vehicle increases and the contact pressure increases, resulting in poor high-speed durability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-080909 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a pneumatic tire that can reduce low-frequency road noise without deteriorating high-speed durability, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to achieve the above object, a pneumatic tire of the present invention includes a tread portion extending in a circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the radially inner side of the sidewall portions, and the tire is mounted in a specified direction relative to a vehicle. In the pneumatic tire, a sealant layer is formed on the inner surface of the tire in the tread portion, and a cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 ] are different, and the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side.

[0007] Further, a method for manufacturing a pneumatic tire according to the present invention is a method for manufacturing the above-described pneumatic tire, in which, after manufacturing the pneumatic tire excluding the sealant layer, a sealant is applied to the inner surface of the tire in the tread portion to form the sealant layer, and a cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 ] are different, and the sealant is applied so that the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side. [Effects of the Invention]

[0008] In the present invention, the cross-sectional area Sin of the sealant layer on the vehicle inner side and the cross-sectional area Sout on the vehicle outer side are different across the tire centerline, with the cross-sectional area Sout on the vehicle outer side being larger than the cross-sectional area Sin on the vehicle inner side. By disposing more sealant on the vehicle outer side in this way, the mass of the tread portion increases, contributing to the reduction of low-frequency road noise. Furthermore, even if a negative camber angle is set when mounted on the vehicle, the heat dissipation performance is not deteriorated across the entire inner surface of the tread portion, as is the case with pneumatic tires equipped with conventional sealant layers, and therefore high-speed durability is not impaired. In this way, low-frequency road noise can be reduced without deteriorating high-speed durability.

[0009] In the pneumatic tire of the present invention, the cross-sectional area Sin on the vehicle inner side and the cross-sectional area Sout on the vehicle outer side preferably satisfy the relationship 1.05≦Sout / Sin≦3.50. This effectively improves low-frequency road noise without deteriorating high-speed durability. Furthermore, while ensuring puncture sealing properties by the sealant layer, the sealant layer is less likely to flow during high-speed driving, allowing the tire to maintain its as-manufactured shape.

[0010] The tire has at least two circumferential grooves extending in the tire circumferential direction on the vehicle-inward side of the tread portion and multiple rows of land portions defined by these circumferential grooves, and the sealant layer disposed on the inner surface of the tire corresponding to the shoulder land portions located on the outermost sides in the tire width direction among the multiple rows of land portions preferably has an average thickness t1 in the range of 2 mm to 3 mm. This allows the sealant layer to effectively improve low-frequency road noise without compromising high-speed durability while ensuring sufficient puncture sealing.

[0011] The tire has at least two circumferential grooves extending in the tire circumferential direction on the vehicle-inward side of the tread portion and multiple rows of land portions defined by these circumferential grooves, the multiple rows of land portions including shoulder land portions located on the outermost sides in the tire width direction and intermediate land portions adjacent thereto, and the average thickness t2 of a sealant layer disposed on the tire inner surface corresponding to the intermediate land portions and the circumferential groove adjacent thereto on the outer side in the tire width direction is preferably in the range of 3 mm to 4 mm. This makes it possible to effectively improve low-frequency road noise while ensuring sufficient puncture sealing performance of the sealant layer without deteriorating high-speed durability.

[0012] The average thickness (tout) of the sealant layer disposed on the vehicle exterior is preferably in the range of 5 mm to 7 mm, which allows the sealant layer to effectively improve low-frequency road noise without impairing high-speed durability while still ensuring sufficient puncture sealing.

[0013] The sealant in the sealant layer is preferably composed of a silicone-based composition, which makes the sealant layer less likely to flow during high-speed driving and allows it to maintain its original shape as manufactured, effectively improving the flow resistance of the sealant layer.

[0014] The silicone composition is preferably a two-component curing silicone, which has low viscosity immediately after mixing the two components, allowing application even at low temperatures.

[0015] It is preferable that the tread portion has a plurality of belt layers, and the sealant layer extends to the end of the narrowest belt layer in the tire width direction, thereby ensuring sufficient puncture sealing by the sealant layer in the ground contact region of the tread portion.

[0016] The tan δ of the sealant layer at 100° C. is preferably in the range of 0.2 to 0.6, which optimizes the flow characteristics of the sealant layer during driving and allows good puncture sealing properties and flow resistance to be maintained.

[0017] In the present invention, the loss tangent tanδ is measured in accordance with JIS K6394 using a viscoelasticity spectrometer in a tensile deformation mode under the conditions of a specified temperature, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2%. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] 2 is an enlarged cross-sectional view showing the vehicle inner side region of the pneumatic tire of FIG. 1. FIG. [Figure 3] 1 is a cross-sectional view illustrating an example of a method for manufacturing a pneumatic tire according to an embodiment of the present invention. [Figure 4] 4 is a plan view showing a part of a sealant layer formed on the inner surface of the tire in the tread portion of the pneumatic tire of FIG. 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Figures 1 and 2 show a pneumatic tire according to an embodiment of the present invention. In Figures 1 and 2, CL denotes the tire center line.

[0020] 1, the mounting direction of a pneumatic tire according to an embodiment of the present invention relative to a vehicle is specified, with IN indicating the area inside the tire center line CL relative to the vehicle when the tire is mounted on the vehicle (hereinafter referred to as the vehicle inner side), and OUT indicating the area outside the tire center line CL relative to the vehicle when the tire is mounted on the vehicle (hereinafter referred to as the vehicle outer side). This pneumatic tire has a tread portion 1 extending in the circumferential direction of the tire to form an annular shape, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged radially inward of the sidewall portions 2.

[0021] At least one carcass layer 4 (one layer in FIG. 1) made up of a plurality of carcass cords arranged in the radial direction is mounted between a pair of bead portions 3. Organic fiber cords such as nylon or polyester are preferably used as the carcass cords that make up the carcass layer 4. An annular bead core 5 is embedded in each bead portion 3, and a bead filler 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0022] Meanwhile, multiple belt layers 7 (two layers in FIG. 1 ) are embedded on the tire outer circumferential side of the carcass layer 4 in the tread portion 1. The belt layer 7 includes multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. The multiple belt layers 7 include a first belt layer 7A located on the innermost side in the tire radial direction and a second belt layer 7B located on the outer side of the first belt layer 7A, and the width of the first belt layer 7A is wider than the width of the second belt layer 7B. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set in the range of 10° to 40°, for example. Steel cords are preferably used as the reinforcing cords of the belt layers 7.

[0023] At least one belt cover layer 8 (two layers in FIG. 1 ) is arranged on the outer periphery of the belt layer 7, with the aim of improving high-speed durability. The belt cover layer 8 has at least one reinforcing cord arranged at an angle of, for example, 5° or less relative to the tire circumferential direction. The belt cover layer 8 preferably has a jointless structure in which a strip material made of at least one reinforcing cord aligned and rubber-coated is continuously wound at an angle of substantially 0° relative to the tire circumferential direction. The reinforcing cord of the belt cover layer 8 is preferably an organic fiber cord such as nylon or aramid.

[0024] The tire internal structure described above is a typical example of a pneumatic tire, but is not limited thereto. As a component constituting the tire inner surface Ts, an inner liner layer 9 is disposed along the carcass layer 4.

[0025] In the pneumatic tire, a plurality of circumferential grooves 10 extending in the tire circumferential direction are formed in the tread portion 1, and a plurality of rows of land portions extending in the tire circumferential direction are defined by these circumferential grooves 10. In this embodiment, the tread portion 1 includes a central land portion 11 located on the tire center line CL, a pair of intermediate land portions 12, 13 adjacent to the central land portion 11, and a pair of shoulder land portions 14, 15 located on the outermost sides in the tire width direction. The tread portion 1 also has an asymmetric tread pattern on the vehicle inner side and the vehicle outer side with the tire center line CL as the boundary.

[0026] A sealant layer 20 is formed continuously in the tire circumferential direction on the tire inner surface Ts of the tread portion 1. The sealant of the sealant layer 20 may be composed of a rubber composition mainly containing butyl rubber, but is preferably composed of a silicone composition. The silicone composition includes a synthetic polymer compound having a main skeleton formed by siloxane bonds.

[0027] Furthermore, the cross-sectional area Sin of the portion of the sealant layer 20 located on the vehicle inner side with respect to the tire center line CL (inner portion Pin in this embodiment) is different from the cross-sectional area Sout of the portion of the sealant layer 20 located on the vehicle outer side with respect to the tire center line CL (outer portion Pout in this embodiment), and the cross-sectional area Sout of the sealant layer 20 on the vehicle outer side (outer portion Pout) is configured to be larger than the cross-sectional area Sin of the vehicle inner side (inner portion Pin). When the cross-sectional area Sout of the sealant layer 20 on the vehicle outer side is made larger than the cross-sectional area Sin of the sealant layer 20 on the vehicle inner side, the thickness of the sealant layer 20 on the vehicle outer side can be made thicker than the thickness of the vehicle inner side, or the width of the sealant layer 20 on the vehicle outer side can be made wider than the width of the sealant layer 20 on the vehicle inner side. When the thickness of the sealant layer 20 is made different on the inside and outside of the vehicle, it may be configured so that there are locally thicker or thinner portions on each side of the inside and outside of the vehicle (see, for example, Figures 1 and 2), or it may be configured so that there is a uniform thickness on each side of the inside and outside of the vehicle, or the thickness may be gradually reduced from the outermost end of the sealant layer 20 to the innermost end of the vehicle.

[0028] In the pneumatic tire described above, the cross-sectional area Sin of the sealant layer 20 on the vehicle inner side differs from the cross-sectional area Sout on the vehicle outer side, with the cross-sectional area Sout on the vehicle outer side being larger than the cross-sectional area Sin on the vehicle inner side, with the tire centerline CL as the boundary. Placing a larger amount of sealant on the vehicle outer side in this manner increases the mass of the tread portion 1, thereby contributing to reducing low-frequency road noise. Furthermore, even if a negative camber angle is set when mounted on a vehicle, the heat dissipation performance is not impaired across the entire inner surface of the tread portion, as is the case with pneumatic tires equipped with conventional sealant layers, and high-speed durability is not impaired. In this way, low-frequency road noise can be reduced without impairing high-speed durability.

[0029] In particular, the cross-sectional area Sin on the vehicle inner side and the cross-sectional area Sout on the vehicle outer side of the sealant layer 20 preferably satisfy the relationship 1.05≦Sout / Sin≦3.50, more preferably 1.20≦Sout / Sin≦2.30, and most preferably 1.30≦Sout / Sin≦2.30. By appropriately setting the ratio Sout / Sin in this way, low-frequency road noise can be effectively improved without deteriorating high-speed durability. Furthermore, while ensuring puncture sealing properties by the sealant layer 20, the sealant layer 20 is less likely to flow during high-speed driving, allowing it to maintain its as-manufactured shape.

[0030] In the above pneumatic tire, the tan δ of the sealant layer 20 at 100°C is preferably in the range of 0.2 to 0.6, and more preferably in the range of 0.3 to 0.5. By appropriately setting the tan δ(100°C) of the sealant layer 20 in this way, the flow characteristics of the sealant layer 20 during driving can be optimized, and good puncture sealing ability and flow resistance can be maintained. If the tan δ(100°C) of the sealant layer 20 is less than 0.2, the puncture sealing ability will decrease, and conversely, if it is greater than 0.6, the flow resistance will decrease.

[0031] The above-described pneumatic tire can be manufactured by the following method. First, as described above, a pneumatic tire is manufactured that includes the tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3. Next, a sealant is applied to the tire inner surface Ts of the tread portion 1 to form a sealant layer 20.

[0032] FIG. 3 shows a specific method for manufacturing a pneumatic tire according to an embodiment of the present invention, and FIG. 4 shows a portion of a sealant layer formed on the tire inner surface in the tread portion. In FIG. 3, a sealant extrusion device 31 mixes sealants supplied from pumps 32 and 33 and continuously discharges the mixed sealant as a strip 21 from a nozzle 34. The sealant extrusion device 31 is configured so that the position of the nozzle 34 can be freely changed. Therefore, by moving the nozzle 34 axially while rotating the tire from a state in which the nozzle 34 is close to the tire inner surface Ts, the sealant strip 21 can be arranged spirally on the tire inner surface Ts while being inclined with respect to the tire circumferential direction Tc (see FIG. 4). The spirally arranged sealant strips 21 are in close contact with each other at their circumferential portions. The spirally arranged sealant strips 21 are integrated to form the sealant layer 20. When applying the sealant to the tire inner surface Ts, the sealant is applied so that the cross-sectional area Sout of the sealant layer 20 on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side, with the tire center line CL as the boundary. In Fig. 3, strips 21 of the same thickness are used and stacked in two layers on the vehicle outer side so that the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side, but the cross-sectional area Sout on the vehicle outer side may be larger than the cross-sectional area Sin on the vehicle inner side by making the thickness of the strips 21 applied to the vehicle outer side thicker than the strips 21 applied to the vehicle inner side.

[0033] The sealant applied to the tire inner surface Ts is preferably composed of a silicone-based composition. This makes the sealant layer 20 less likely to flow during high-speed driving and allows it to maintain its shape as manufactured, which is effective in improving the flow resistance of the sealant layer 20. Furthermore, since silicone-based compositions have good fluidity even at low temperatures, it is preferable to lower the temperature of the sealant applied to the tire inner surface Ts to below 70°C. This reduces the impact of heat on the tire and prevents deterioration of tire performance. If this temperature is 70°C or higher, the impact of heat on the tire will be greater, which will cause deterioration of tire performance. In particular, it is desirable for the temperature of the sealant applied to the tire inner surface Ts to be 40°C or lower. Furthermore, from the perspective of the fluidity of the silicone-based composition, the lower limit of the temperature of the sealant applied to the tire inner surface Ts is preferably 20°C.

[0034] As the silicone-based composition constituting the sealant of the sealant layer 20, one-component curing silicone or two-component curing silicone can be used, but it is particularly preferable to use two-component curing silicone. An example of one-component curing silicone is moisture-curing silicone. Two-component curing silicone is composed of a first component and a second component, and mixing these two components initiates a curing reaction, ensuring the stability of the sealant layer 20 after curing. In the above-mentioned device, the first component and the second component of the two-component curing silicone are supplied from pumps 32 and 33, respectively. Two-component curing silicone has low viscosity immediately after mixing the two components, so it can be applied even at low temperatures.

[0035] Two-component curing silicones are composed of, for example, a condensation-curable silyl-terminated polymer, a silane crosslinker, a condensation catalyst, a filler, and the like. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers having silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylenes having silyl groups. Examples of silane crosslinkers include alkoxy-functional silanes, oximosilanes, acetoxysilanes, and enoxysilanes. Examples of fillers include iron oxide, titanium dioxide, carbon black, and talc. Examples of condensation catalysts include titanates and zirconates. These condensation-curable silyl-terminated polymers, silane crosslinkers, condensation catalysts, and fillers are stored in a first and second liquid form in a combination that does not promote a curing reaction, and are mixed when used.

[0036] In the above-described pneumatic tire, the thickness tout of the sealant layer 20 (outer portion Pout) disposed on the vehicle outer side is preferably in the range of 5 mm to 7 mm. The average thickness tout is the value (Sout / Wout) obtained by dividing the cross-sectional area Sout of the sealant layer 20 by the width Wout of the sealant layer 20 disposed on the vehicle outer side. By appropriately setting the thickness tout of the sealant layer 20 in this manner, it is possible to effectively improve low-frequency road noise without deteriorating high-speed durability while ensuring sufficient puncture sealing performance of the sealant layer. Here, if the thickness tout of the sealant layer 20 is less than 5 mm, the puncture sealing performance will be reduced, and conversely, if it exceeds 7 mm, the sealant layer 20 will be more likely to flow during high-speed driving, tending to deteriorate flow resistance.

[0037] The average thickness t1 of the sealant layer 20 (see FIG. 2) is preferably in the range of 2 mm to 3 mm. The average thickness t1 is the value (S1 / W1) obtained by dividing the cross-sectional area S1 of the sealant layer 20 by the width W1 of the sealant layer 20 disposed on the tire inner surface Ts corresponding to the vehicle-inner shoulder land portion 15. The measurement target for the average thickness t1 is a portion of the entire sealant layer 20 that is on the outer side in the tire width direction of a normal to the tire inner surface Ts that passes through the tire width direction end of the vehicle-inner shoulder land portion 15.

[0038] By appropriately setting the average thickness t1 in this manner, it is possible to effectively improve low-frequency road noise without deteriorating high-speed durability while ensuring sufficient puncture sealing performance by the sealant layer 20. If the average thickness t1 of the sealant layer 20 is less than 2 mm, the puncture sealing performance tends to decrease, and conversely, if it exceeds 3 mm, the high-speed durability tends to decrease.

[0039] The average thickness t2 of the sealant layer 20 (see FIG. 2) is preferably in the range of 3 mm to 4 mm. The average thickness t2 is the value (S2 / W2) obtained by dividing the cross-sectional area S2 of the sealant layer 20 by the width W2 of the sealant layer 20 disposed on the tire inner surface Ts corresponding to the vehicle-inner intermediate land portion 13 and the circumferential groove 10 adjacent thereto on the tire width direction outer side. The measurement target for the average thickness t2 is a portion of the entire sealant layer 20 between a normal to the tire inner surface Ts passing through the tire width direction inner end of the vehicle-inner intermediate land portion 13 and a normal to the tire inner surface Ts passing through the tire width direction end of the vehicle-inner shoulder land portion 15.

[0040] By appropriately setting the average thickness t2 in this way, it is possible to effectively improve low-frequency road noise while ensuring sufficient puncture sealing performance of the sealant layer without compromising high-speed durability. If the average thickness t2 of the sealant layer 20 is less than 3 mm, the puncture sealing performance will be reduced, and if it is more than 4 mm, the high-speed durability will tend to be reduced.

[0041] It is also preferable that the sealant layer 20 extends to the end portion in the tire width direction of the narrowest second belt layer 7B, thereby ensuring sufficient puncture sealing performance by the sealant layer 20 in the ground contact region of the tread portion 1. [Example]

[0042] In a pneumatic tire having a tire size of 255 / 40R21 and equipped with a tread portion, a pair of sidewall portions, and a pair of bead portions, and having a specified mounting direction on a vehicle, a sealant layer was formed on the inner surface of the tire in the tread portion, and tires of a conventional example, a comparative example, and examples 1 to 8 were manufactured with the cross-sectional area relationship of the sealant layer, the cross-sectional area ratio Sout / Sin, the average thickness t1 of the sealant layer, the average thickness t2 of the sealant layer, the average thickness tout of the sealant layer, the type of sealant, and the tan δ (100°C) of the sealant layer set as shown in Table 1.

[0043] These test tires were evaluated for road noise, high-speed durability and flow resistance by the following test methods, and the results are shown in Table 1.

[0044] Road noise: Each test tire was mounted on a 21x9.0J rim wheel and fitted to a 2000cc class test vehicle, and a test driver conducted a sensory evaluation of road noise while driving on a paved road surface at an air pressure of 270kPa, a load of 70% of the maximum load capacity, and a speed of 60km / h. The evaluation results were expressed as an index, with the conventional example being set at 100. The higher the index value, the lower the road noise.

[0045] Fast durability: Each test tire was mounted on a wheel with a rim size of 21 x 9.0J, inflated to 340 kPa, and mounted on an indoor drum testing machine (drum diameter 1707 mm). With a camber angle of -3.0° and a load of 6.02 kN, the running speed was increased in 10 km / h increments from 250 km / h, and the tire was run for 10 minutes at each speed, and the speed reached until the tire broke was measured. The evaluation results were expressed as an index, with the conventional example being 100. A higher index value indicates better high-speed durability.

[0046] Flow Resistance: Each test tire was mounted on a 21x9.0J rim wheel and mounted on an indoor drum testing machine (drum diameter 1707mm). The tire was air-pressurized to 230kPa, the load was 80% of the maximum load capacity, and the speed was 200km / h. After a one-hour running test, the degree of sealant flow was checked. The evaluation results were indicated as follows: no flow was indicated by "◎", flow (less than 1 / 8 of the total) was indicated by "〇", flow (1 / 8 to 1 / 4 of the total) was indicated by "△", and flow (1 / 4 or more of the total) was indicated by "×".

[0047] [Table 1]

[0048] As can be seen from Table 1, the pneumatic tires of Examples 1 to 8 were able to reduce road noise without deteriorating high-speed durability compared to the conventional tire.

[0049] In the comparative example, the sealant was positioned so that the cross-sectional area Sin of the sealant layer on the inside of the vehicle was larger than the cross-sectional area Sout of the sealant layer on the outside of the vehicle, which reduced road noise but significantly deteriorated high-speed durability.

[0050] The present disclosure includes the following inventions [1] to

[10] . Invention [1] is a pneumatic tire having a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radially inner side of the sidewall portions, and the tire mounting direction relative to a vehicle is specified. In this tire, a sealant layer is formed on the tire inner surface in the tread portion, and a cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 ] are different, and the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side. Invention [2] is the pneumatic tire according to invention [1], characterized in that the cross-sectional area Sin on the vehicle inner side and the cross-sectional area Sout on the vehicle outer side satisfy the relationship 1.05≦Sout / Sin≦3.50. Invention [3] is a pneumatic tire according to invention [1] or [2], characterized in that the tread portion has at least two circumferential grooves extending in the tire circumferential direction on the vehicle inner side, and multiple rows of land portions separated by these circumferential grooves, and the average thickness t1 of the sealant layer arranged on the inner surface of the tire corresponding to the shoulder land portions located on the outermost sides in the tire width direction among the multiple rows of land portions is in the range of 2 mm to 3 mm. Invention [4] is a pneumatic tire according to any one of inventions [1] to [3], characterized in that the tread portion has at least two circumferential grooves extending in the tire circumferential direction on the vehicle inner side, and multiple rows of land portions separated by these circumferential grooves, the multiple rows of land portions including shoulder land portions located on the outermost sides in the tire width direction and intermediate land portions adjacent thereto, and the average thickness t2 of the sealant layer arranged on the tire inner surface corresponding to the intermediate land portions and the circumferential groove adjacent thereto on the outer side in the tire width direction is in the range of 3 mm to 4 mm. Invention [5] is a pneumatic tire according to any one of inventions [1] to [4], characterized in that the average thickness tout of the sealant layer arranged on the outer side of the vehicle is in the range of 5 mm to 7 mm. Invention [6] is the pneumatic tire according to any one of inventions [1] to [5], characterized in that the sealant of the sealant layer is composed of a silicone-based composition. Invention [7] is the pneumatic tire according to invention [6], characterized in that the silicone composition is a two-component curing silicone. Invention [8] is a pneumatic tire according to any one of inventions [1] to [7], characterized in that the tread portion has a plurality of belt layers, and the sealant layer extends to the end of the narrowest belt layer in the tire width direction among the plurality of belt layers. Invention [9] is the pneumatic tire according to any one of inventions [1] to [8], characterized in that the tan δ at 100° C. of the sealant layer is in the range of 0.2 to 0.6. Invention

[10] is a method for manufacturing a pneumatic tire according to any one of Inventions [1] to [9], wherein after manufacturing a pneumatic tire excluding the sealant layer, a sealant is applied to the inner surface of the tire in the tread portion to form the sealant layer, and a cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 and applying the sealant so that the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side. [Explanation of symbols]

[0051] 1 Tread section 2 Sidewall 3 Bead section 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 10 Circumferential groove 11~15 Rikubu 20 Sealant Layer CL Tire centerline Ts tire inner surface

Claims

1. A pneumatic tire having a tread portion extending in a circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the radially inner side of the sidewall portions, the tire being mounted in a specified direction relative to a vehicle, A sealant layer is formed on the inner surface of the tire in the tread portion, and a cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 ] are different, and the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side.

2. 2. The pneumatic tire according to claim 1, wherein the cross-sectional area Sin on the vehicle inner side and the cross-sectional area Sout on the vehicle outer side satisfy the relationship 1.05≦Sout / Sin≦3.

50.

3. 3. The pneumatic tire according to claim 1, wherein the tread portion has, on a vehicle-inward side thereof, at least two circumferential grooves extending in the tire circumferential direction and a plurality of rows of land portions partitioned by these circumferential grooves, and the sealant layer disposed on the inner surface of the tire corresponding to the shoulder land portions located on the outermost sides in the tire width direction among the plurality of rows of land portions has an average thickness t1 in the range of 2 mm to 3 mm.

4. 3. The pneumatic tire according to claim 1, wherein the tread portion has, on a vehicle inner side thereof, at least two circumferential grooves extending in the tire circumferential direction and a plurality of rows of land portions partitioned by these circumferential grooves, the plurality of rows of land portions including shoulder land portions located on the outermost sides in the tire width direction and intermediate land portions adjacent thereto, and the average thickness t2 of the sealant layer arranged on the inner surface of the tire corresponding to the intermediate land portion and the circumferential groove adjacent thereto on the outer side in the tire width direction is in the range of 3 mm to 4 mm.

5. 3. The pneumatic tire according to claim 1, wherein the sealant layer disposed on the outer side of the vehicle has an average thickness tout in the range of 5 mm to 7 mm.

6. 3. The pneumatic tire according to claim 1, wherein the sealant in the sealant layer is made of a silicone-based composition.

7. 7. The pneumatic tire according to claim 6, wherein the silicone composition is a two-component curing silicone.

8. 3. The pneumatic tire according to claim 1, wherein the tread portion includes a plurality of belt layers, and the sealant layer extends to an end portion in the tire width direction of a belt layer having a narrowest width among the plurality of belt layers.

9. 3. The pneumatic tire according to claim 1, wherein the sealant layer has a tan δ at 100° C. in the range of 0.2 to 0.

6.

10. A method for manufacturing the pneumatic tire according to claim 1 or 2, After manufacturing a pneumatic tire excluding the sealant layer, When forming the sealant layer by applying the sealant to the inner surface of the tire in the tread portion, the cross-sectional area Sin [mm 2 ] and the cross-sectional area Sout [mm 2 and the sealant is applied so that the cross-sectional area Sout on the vehicle outer side is larger than the cross-sectional area Sin on the vehicle inner side.

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