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 improve ride comfort without deteriorating rolling resistance.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 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 Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer 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, and more particularly to a pneumatic tire that enables improved ride comfort without deteriorating rolling resistance, 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] Furthermore, in order to improve ride comfort in pneumatic tires, the thickness of the tread portion is increased to attenuate tire vibrations, but increasing the thickness of the tread portion poses the problem of increased rolling resistance. [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 enables improved ride comfort without deteriorating rolling resistance, 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 Sin on the vehicle inside is larger than the cross-sectional area Sout on the vehicle outside.

[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 Sin on the vehicle inside is larger than the cross-sectional area Sout on the vehicle outside. [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 Sin on the vehicle inner side being larger than the cross-sectional area Sout on the vehicle outer side. By disposing a larger amount of sealant on the vehicle inner side in this way, tire vibrations can be damped, thereby improving ride comfort. In particular, when a negative camber angle is set when the tire is mounted on a vehicle, the contact length of the shoulder portion on the vehicle inner side becomes longer and the contact pressure increases, resulting in a significant improvement in ride comfort. Furthermore, by disposing a larger amount of sealant on the vehicle inner side to suppress heat dissipation during driving, the deterioration of rolling resistance in the entire tread portion can be minimized. In this way, ride comfort can be improved without worsening rolling resistance.

[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 1.4≦Sin / Sout≦3.5. This effectively improves ride comfort without deteriorating rolling resistance. 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 groove area Gin [mm 2 ] is the groove area on the outside of the vehicle Gout [mm 2 In a pneumatic tire having an asymmetric tread pattern, rolling resistance can be improved by placing a larger amount of sealant on the inner side of the vehicle where the groove area is relatively large, thereby suppressing heat dissipation during driving.

[0011] The average thickness tin of the sealant layer disposed on the inside of the vehicle is preferably in the range of 5 mm to 7 mm, which can effectively improve ride comfort without worsening rolling resistance.

[0012] The tire tread has at least two circumferential grooves extending in the tire circumferential direction and multiple rows of land portions defined by these circumferential grooves on the vehicle-outer side, and the sealant layer disposed on the tire inner surface 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 3 mm to 4 mm. This allows ride comfort to be effectively improved without deteriorating rolling resistance while ensuring sufficient puncture sealing by the sealant layer.

[0013] The tread portion has at least two circumferential grooves extending in the tire circumferential direction and multiple rows of land portions defined by these circumferential grooves on the vehicle-outer side, and these multiple rows of land portions include 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 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 4 mm to 5 mm. This makes it possible to effectively improve ride comfort without deteriorating rolling resistance while ensuring sufficient puncture sealing performance of the sealant layer.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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]

[0019] [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 outer 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

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 Sin of the sealant layer 20 on the vehicle inner side (inner portion Pin) is larger than the cross-sectional area Sout of the vehicle outer side (outer portion Pout) of the sealant layer 20. When the cross-sectional area Sin of the sealant layer 20 on the vehicle inner side is made larger than the cross-sectional area Sout of the sealant layer 20 on the vehicle outer side, the thickness of the sealant layer 20 on the vehicle inner side can be made thicker than the thickness on the vehicle outer side, or the width of the sealant layer 20 on the vehicle inner side can be made wider than the width on the vehicle outer 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 of the sealant layer 20 may be gradually thinner from the innermost end of the vehicle to the outermost end of the vehicle.

[0029] In the above-described pneumatic tire, 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 Sin on the vehicle inner side being larger than the cross-sectional area Sout on the vehicle outer side, with the tire centerline CL as the boundary. By placing a larger amount of sealant on the vehicle inner side, tire vibrations can be damped, thereby improving ride comfort. In particular, when a negative camber angle is set when the tire is mounted on a vehicle, the contact length of the shoulder portion on the vehicle inner side is longer and the contact pressure is higher, resulting in a significant improvement in ride comfort. Furthermore, by placing a larger amount of sealant on the vehicle inner side to suppress heat dissipation during driving, the deterioration of rolling resistance in the tread portion 1 as a whole can be minimized. In this way, ride comfort can be improved without worsening rolling resistance.

[0030] 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 1.4≦Sin / Sout≦3.5, and more preferably 1.5≦Sin / Sout≦2.3. By appropriately setting the ratio Sin / Sout in this manner, ride comfort can be effectively improved without deteriorating rolling resistance. Furthermore, while ensuring puncture sealing performance 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.

[0031] 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.

[0032] 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.

[0033] 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 Sin of the sealant layer 20 on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer 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 inner side so that the cross-sectional area Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer side, but the thickness of the strips 21 applied to the vehicle inner side may be made thicker than the strips 21 applied to the vehicle outer side so that the cross-sectional area Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer side.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In the pneumatic tire, the groove area Gin [mm 2 ] is the groove area Gout [mm 2 In a pneumatic tire having an asymmetric tread pattern, rolling resistance can be improved by placing a larger amount of sealant on the inner side of the vehicle where the groove area is relatively large, thereby suppressing heat dissipation during driving.

[0038] In the pneumatic tire, the average thickness tin of the sealant layer 20 (inner portion Pin) disposed on the vehicle inner side is preferably in the range of 5 mm to 7 mm. The average thickness tin is the value (Sin / Win) obtained by dividing the cross-sectional area Sin of the sealant layer 20 disposed on the vehicle inner side by the width Win of the sealant layer 20. By appropriately setting the thickness tin of the sealant layer 20 in this manner, it is possible to effectively improve ride comfort without deteriorating rolling resistance. Here, if the thickness tin of the sealant layer 20 is less than 5 mm, 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.

[0039] The average thickness t1 of the sealant layer 20 (see FIG. 2) is preferably in the range of 3 mm to 4 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-outer shoulder land portion 14. 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-outer shoulder land portion 14.

[0040] By appropriately setting the average thickness t1 in this way, it is possible to effectively improve ride comfort without worsening rolling resistance while ensuring sufficient puncture sealing performance by the sealant layer 20. If the average thickness t1 of the sealant layer 20 is less than 3 mm, the puncture sealing performance will decrease, and conversely, if it exceeds 4 mm, the rolling resistance will tend to worsen due to the increased weight.

[0041] The average thickness t2 of the sealant layer 20 (see FIG. 2) is preferably in the range of 4 mm to 5 mm. The average thickness t2 is the value (S2 / W2) obtained by dividing the cross-sectional area S2 of the sealant layer 20 arranged on the tire inner surface Ts corresponding to the vehicle-outer intermediate land portion 12 and the circumferential groove 10 adjacent thereto on the outer side in the tire width direction by the width W2 of the sealant layer 20. 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-outer intermediate land portion 12 and a normal to the tire inner surface Ts passing through the tire width direction end of the vehicle-outer shoulder land portion 14.

[0042] By appropriately setting the average thickness t2 in this way, ride comfort can be effectively improved without worsening rolling resistance while ensuring sufficient puncture sealing by the sealant layer. If the average thickness t2 of the sealant layer 20 is less than 4 mm, puncture sealing performance will be reduced, and conversely, if it is more than 5 mm, rolling resistance will tend to be worsened due to increased weight.

[0043] 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]

[0044] In a pneumatic tire having a tire size of 255 / 40R21 and including 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 the conventional example, comparative examples 1 and 2, and examples 1 to 7 were manufactured with the sealant layer cross-sectional area relationship, cross-sectional area ratio Sin / Sout, groove area relationship, average sealant layer thickness tin, average sealant layer thickness t1, average sealant layer thickness t2, sealant type, and sealant layer tan δ (100°C) set as shown in Table 1.

[0045] These test tires were evaluated for ride comfort, rolling resistance and flow resistance by the following test methods, and the results are shown in Table 1.

[0046] Ride comfort: 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 ride comfort when 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 50km / h. The evaluation results were expressed as an index, with the conventional example being set at 100. The higher the index value, the better the ride comfort.

[0047] Rolling resistance: Each test tire was mounted on a 21x9.0J rim wheel and attached to a rolling resistance tester, and rolling resistance was measured at an air pressure of 250kPa, a load of 6.67kN, and a speed of 80km / h. The evaluation results were expressed as an index using the reciprocal of the measured value, with the conventional example being set at 100. The higher the index value, the lower the rolling resistance.

[0048] 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 "×".

[0049] [Table 1]

[0050] As can be seen from Table 1, the pneumatic tires of Examples 1 to 7 were able to improve the ride comfort without worsening the rolling resistance compared to the conventional tire.

[0051] In the pneumatic tire of Comparative Example 1, the sealant was arranged so that the cross-sectional area Sin of the sealant layer on the inside of the vehicle was the same as the cross-sectional area Sout of the sealant layer on the outside of the vehicle, and the thickness of the sealant layer was made thicker than in the conventional tire, which resulted in a significant improvement in ride comfort but a deterioration in rolling resistance.In the pneumatic tire of Comparative Example 2, the sealant was arranged so that the cross-sectional area Sout of the sealant layer on the outside of the vehicle was larger than the cross-sectional area Sin of the sealant layer on the inside of the vehicle, which resulted in an improvement in ride comfort but a deterioration in rolling resistance.

[0052] The present disclosure includes the following inventions [1] to

[11] . 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 Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer 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 1.4≦Sin / Sout≦3.5. The invention [3] is a groove area Gin [mm 2 ] is the groove area Gout [mm 2 ] is a pneumatic tire according to invention [1] or [2], characterized in that Invention [4] is a pneumatic tire according to any one of inventions [1] to [3], characterized in that the average thickness tin of the sealant layer arranged on the inside of the vehicle is in the range of 5 mm to 7 mm. Invention [5] is a pneumatic tire according to any one of inventions [1] to [4], characterized in that the tread portion has at least two circumferential grooves extending in the tire circumferential direction on the vehicle-outer side thereof and multiple rows of land portions partitioned 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 3 mm to 4 mm. Invention [6] is a pneumatic tire according to any one of inventions [1] to [5], characterized in that the tread portion has at least two circumferential grooves extending in the tire circumferential direction and multiple rows of land portions partitioned by these circumferential grooves on the vehicle-outer side, 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 inner surface of the tire 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 4 mm to 5 mm. Invention [7] is a pneumatic tire according to any one of inventions [1] to [6], 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 [8] is the pneumatic tire according to any one of inventions [1] to [7], characterized in that the sealant of the sealant layer is made of a silicone-based composition. Invention [9] is the pneumatic tire according to invention [8], characterized in that the silicone composition is a two-component curing silicone. Invention

[10] is the pneumatic tire according to any one of inventions [1] to [9], characterized in that the tan δ at 100° C. of the sealant layer is in the range of 0.2 to 0.6. Invention

[11] is a method for manufacturing a pneumatic tire according to any one of Inventions [1] to

[10] , 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 Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer side. [Explanation of symbols]

[0053] 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 Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer 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 1.4≦Sin / Sout≦3.

5.

3. The groove area Gin [mm 2 ] is the groove area Gout [mm 2 3. The pneumatic tire according to claim 1, wherein the axial length of the pneumatic tire is greater than 1 / 2.

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

5. 3. The pneumatic tire according to claim 1, wherein the tread portion has at least two circumferential grooves extending in the tire circumferential direction and a plurality of rows of land portions partitioned by these circumferential grooves on the vehicle-outer side, 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 3 mm to 4 mm.

6. 3. The pneumatic tire according to claim 1, wherein the tread portion has at least two circumferential grooves extending in the tire circumferential direction and a plurality of rows of land portions partitioned by these circumferential grooves on the vehicle-outer side, 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 4 mm to 5 mm.

7. 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.

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

9. 9. The pneumatic tire according to claim 8, wherein the silicone-based composition is a two-component curing silicone.

10. 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.

11. 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 Sin on the vehicle inner side is larger than the cross-sectional area Sout on the vehicle outer side.

Images