Pneumatic tire and method for manufacturing the same

Abstract

Provided are a pneumatic tire and a method for manufacturing the same that enable good retention of the sealing property by a sealant layer. In a pneumatic tire including a tread portion 1 that extends in the tire circumferential direction and forms 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 the tire radial direction inner side of these sidewall portions 2, a sealant layer 20 having a structure in which a strip material 21 of a sealant is spirally disposed along the tire circumferential direction on the tire inner surface 10 in the tread portion 1 is formed, and the sealant is composed of a silicone-based composition.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire provided with a sealant layer on the inner surface of the tire in the tread portion and a method for manufacturing the same, and more particularly, to a pneumatic tire and a method for manufacturing the same that enable good retention of the sealing property by the sealant layer.

Background Art

[0002] In a pneumatic tire, it has been proposed to provide a sealant layer on the inner side in the tire radial direction of the inner liner layer in the tread portion. In such a pneumatic tire, when a foreign object such as a nail pierces the tread portion, the sealant flows into the through-hole, thereby suppressing a decrease in air pressure and enabling driving to be maintained.

[0003] Conventionally, as the sealant constituting the sealant layer, a rubber composition mainly composed of butyl rubber is generally used (see, for example, Patent Documents 1 to 3). Examples of butyl rubber include halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) in addition to butyl rubber (IIR). Such a sealant is applied to the inner surface of the tire in a state of being heated to a high temperature and softened (see, for example, Patent Document 4). More specifically, the sealant layer is formed by arranging a strip material of the sealant in a softened state by heating to a high temperature in a spiral shape along the tire circumferential direction on the inner surface of the tire.

[0004] However, in the sealant layer formed as described above, since the sealant cools down before the circumferential portions of the sealant strip material fit together, the integrality of the circumferential portions of the sealant strip material is not good, and as a result, there is a problem that the sealing property by the sealant layer becomes insufficient. In addition, if the integrality of the circumferential portions of the sealant strip material is insufficient, the sealant layer easily flows toward the center side of the tread portion due to the centrifugal force generated during tire rotation, which also causes a decrease in the sealing property.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 6583456 [Patent Document 2] Japanese Patent Publication No. 6620851 [Patent Document 3] Japanese Patent Publication No. 7319533 [Patent Document 4] Japanese Patent Publication No. 6124967 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] An object of the present invention is to provide a pneumatic tire capable of favorably maintaining the sealing performance by a sealant layer and a method for manufacturing the same. [Means for Solving the Problems]

[0007] The pneumatic tire of the present invention for achieving the above object is a pneumatic tire including 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 inner side in the tire radial direction of these sidewall portions. A sealant layer having a structure in which a belt-like material of a sealant is spirally disposed along the tire circumferential direction is formed on the inner surface of the tire in the tread portion, and the sealant is composed of a silicone-based composition.

[0008] The method for manufacturing a pneumatic tire of the present invention for achieving the above object is a method for manufacturing the above-described pneumatic tire. After manufacturing a pneumatic tire excluding the sealant layer, When forming the sealant layer by applying a sealant composed of a silicone-based composition to the inner surface of the tire in the tread portion, the temperature of the sealant applied to the inner surface of the tire is made lower than 70°C.

Advantages of the Invention

[0009] In the present invention, a sealant layer having a structure in which a sealant strip is spirally arranged along the tire circumferential direction on the inner surface of the tire in the tread portion is formed. Since the sealant is composed of a silicone-based composition, in the curing reaction process of the silicone-based composition, the circumferential portions of the sealant strip are easily adapted to each other, and the integrity of the circumferential portions of the sealant strip becomes good. Therefore, the sealing performance of the sealant layer can be improved. Further, since the integrity of the circumferential portions of the sealant strip is good, it becomes difficult for the sealant layer to flow toward the center side in the tire width direction due to the centrifugal force generated during tire rotation, and this also contributes to the improvement of the sealing performance. Furthermore, the sealant composed of the silicone-based composition can be applied at a low temperature. For example, since the temperature of the sealant applied to the inner surface of the tire can be lower than 70°C, there is also an advantage that the influence of heat on the tire can be reduced and the deterioration of tire performance can be avoided.

[0010] In the present invention, the silicone-based composition is preferably a two-component curable silicone. Since the two-component curable silicone has a low viscosity immediately after the two components are mixed, it can be applied even at a low temperature.

[0011] In the present invention, the glass transition temperature of the sealant preferably ranges from -120°C to -40°C. By using a sealant with a low glass transition temperature, it is possible to ensure good puncture sealing performance in a low-temperature environment.

[0012] In the present invention, the thickness of the sealant layer preferably ranges from 2.0 mm to 5.0 mm. Thereby, while ensuring the puncture sealing performance, it is possible to suppress the deterioration of the rolling resistance due to the increase in tire weight and to suppress the uneven distribution of the sealant layer caused by the flow of the sealant.

[0013] In the present invention, when a belt layer including a belt cord inclined with respect to the tire circumferential direction is embedded in the tread portion, it is preferable that the inclination direction of the sealant strip with respect to the tire circumferential direction is out of phase with the inclination direction of the belt cord of the belt layer located on the innermost side in the tire radial direction. In a pneumatic tire, ply steer occurs due to the orientation of the belt cords in the belt layer, and the orientation of the sealant strip also contributes to ply steer. Therefore, by setting the inclination direction of the sealant strip with respect to the tire circumferential direction to be out of phase with the inclination direction of the belt cord of the belt layer located on the innermost side in the tire radial direction, it becomes possible to reduce ply steer.

[0014] In the present invention, when a belt layer including a belt cord inclined with respect to the tire circumferential direction is embedded in the tread portion, it is preferable that the width of the sealant layer is 90% or more of the width of the belt layer located on the innermost side in the tire radial direction. In particular, it is preferable that the end portion of the sealant layer is disposed on the outer side in the tire width direction than the end portion of the belt layer located on the innermost side in the tire radial direction. By making the width of the sealant layer sufficiently large, it is possible to effectively prevent a puncture of a pneumatic tire.

[0015] In the present invention, when a belt cover layer including an organic fiber cord oriented in the tire circumferential direction is embedded on the outer peripheral side of the belt layer in the tread portion, it is preferable that the end portion of the sealant layer is disposed on the outer side in the tire width direction than the end portion of the belt cover layer. By making the width of the sealant layer sufficiently large, it is possible to effectively prevent a puncture of a pneumatic tire.

[0016] In the present invention, at all locations of the belt layer located on the innermost side in the tire radial direction, it is preferable that the distance L from the belt layer to the sealant layer is 10 mm or less. As a result, when a foreign object such as a nail penetrates the tread portion, the sealant easily flows into the belt layer, so that good puncture sealing performance can be ensured.

[0017] In the present invention, it is preferable that the ratio of the thickness S of the sealant layer to the distance L from the belt layer located at the innermost side in the tire radial direction to the sealant layer satisfies the relationship of S / L ≥ 0.3. By making the thickness S of the sealant layer sufficiently larger than the distance L, good puncture sealing performance can be ensured.

[0018] In the present invention, it is preferable that a sound-absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer. In this case, since the sound-absorbing material can be installed with respect to the sealant layer applied at a low temperature, damage to the sound-absorbing material can be avoided and its sound-absorbing effect can be maintained well.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 to 3 show a pneumatic tire according to an embodiment of the present invention.

[0021] As shown in Fig. 1, the pneumatic tire of the present embodiment includes a tread portion 1 extending in the tire circumferential direction and forming an annular shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed on the inner side in the tire radial direction of these sidewall portions 2.

[0022] A carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded back from the inner side to the outer side of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer circumference of the bead core 5.

[0023] On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of belt cords inclined with respect to the tire circumferential direction, and are arranged such that the belt cords cross each other between the layers. In the belt layer 7, the inclination angle of the belt cord with respect to the tire circumferential direction is set, for example, in the range of 10° to 40°. As the belt cord of the belt layer 7, a steel cord is preferably used.

[0024] On the outer peripheral side of the belt layer 7, at least one belt cover layer 8 is disposed in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction for the purpose of improving high-speed durability. It is desirable that this belt cover layer 8 has a jointless structure in which a strip material formed by rubber-coating at least one reinforcing cord aligned is continuously wound at substantially 0° with respect to the tire circumferential direction. As the reinforcing cord of the belt cover layer 8, organic fiber cords such as nylon and polyethylene terephthalate (PET) are preferably used.

[0025] Note that the above-described tire internal structure shows a typical example in a pneumatic tire, but is not limited thereto. In the tread portion 1, various grooves including a plurality of main grooves 11 extending in the tire circumferential direction are formed.

[0026] In the above pneumatic tire, a sealant layer 20 is formed on the inner surface 10 of the tread portion 1 so as to be continuous in the tire circumferential direction. It is preferable that the center position of the sealant layer 20 in the tire width direction coincides with the tire equator, but the center position may be shifted toward either one side in the tire width direction from the tire equator. The distance in the tire width direction between the center position of the sealant layer 20 in the tire width direction and the tire equator is preferably 10 mm or less, and more preferably 5 mm or less. Thereby, the sealant layer 20 does not adversely affect the tire balance. As shown in FIG. 3, the sealant layer 20 has a structure in which the sealant strip 21 is spirally arranged along the tire circumferential direction. The sealant of the sealant layer 20 is composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound having a main skeleton formed by a siloxane bond.

[0027] The above-described pneumatic tire can be manufactured by the following method. First, a pneumatic tire is manufactured which includes the tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3 as described above, and in which the belt layer 7 and the belt cover layer 8 are embedded in the tread 1 portion. Next, a sealant made of a silicone-based composition is applied to the inner surface 10 of the tread portion 1 to form the sealant layer 20.

[0028] FIG. 4 shows a specific manufacturing method of the pneumatic tire of FIG. 1, and FIG. 5 shows a sealant layer formed on the inner surface of the tire in the tread portion. In FIG. 4, the sealant extruding device 31 mixes the sealant supplied from the pumps 32 and 33, and continuously discharges the mixed sealant from the nozzle 34 as a strip material 21. The sealant extruding device 31 is configured such that the position of the nozzle 34 is displaceable. Therefore, by moving the nozzle 34 in the tire axial direction while rotating the tire from a state where the nozzle 34 is close to the inner surface 10 of the tire, the strip material 21 of the sealant can be spirally arranged on the inner surface 10 of the tire while being inclined with respect to the tire circumferential direction Tc (see FIG. 5). The circumferential portions of the strip material 21 of the sealant arranged in a spiral shape are in close contact with each other. The strip material 21 of the sealant arranged in this spiral shape is integrated to form the sealant layer 20.

[0029] In the above-described pneumatic tire, a sealant layer 20 having a structure in which a strip material 21 of the sealant is spirally arranged along the tire circumferential direction on the inner surface 10 of the tire in the tread portion 1 is formed. Since the sealant is composed of a silicone-based composition, the circumferential portions of the sealant strip material 21 are easily adapted to each other in the curing reaction process of the silicone-based composition, and the integrality of the circumferential portions of the sealant strip material 21 becomes good. Therefore, the sealing performance of the sealant layer 20 can be improved. Further, since the integrality of the circumferential portions of the sealant strip material 21 is good, it becomes difficult for the sealant layer 20 to flow toward the center side in the tire width direction due to the centrifugal force generated during tire rotation, and this also contributes to the improvement of the sealing performance. Furthermore, when a silicone-based composition is used as the sealant of the sealant layer 20, there are also advantages of excellent weather resistance and low temperature dependence of physical properties.

[0030] Since the silicone-based composition has good fluidity even at low temperatures, it is preferable to keep the temperature of the sealant applied to the inner surface 10 of the tire below 70°C. This can reduce the influence of heat on the tire and avoid deterioration of tire performance. If this temperature is 70°C or higher, the influence of heat on the tire becomes significant and becomes a factor in deteriorating tire performance. In particular, it is desirable that the temperature of the sealant applied to the inner surface 10 of the tire be 35°C or lower. Also, from the viewpoint of the fluidity of the silicone-based composition, the lower limit of the temperature of the sealant applied to the inner surface 10 of the tire is preferably 20°C.

[0031] As the silicone-based composition constituting the sealant of the sealant layer 20, one-component curable silicone or two-component curable silicone can be used, but it is particularly preferable to use two-component curable silicone. Examples of one-component curable silicone include moisture-curable silicone. Two-component curable silicone is composed of a first liquid and a second liquid. By mixing these first and second liquids, the curing reaction starts, and stability as the sealant layer 20 is ensured after curing. In the above-described apparatus, the first liquid and the second liquid of the two-component curable silicone are supplied from pumps 32 and 33, respectively. Since the two-component curable silicone has a low viscosity immediately after the two liquids are mixed, it can be applied even at low temperatures. In particular, it is preferable that the two-component curable silicone has a period of 5 days or more until complete curing.

[0032] Two-component curable silicone is composed of, for example, a condensation curable silyl-terminated polymer, a silane crosslinking agent, a condensation catalyst, a filler, etc. Examples of the condensation curable silyl-terminated polymer include polydialkylsiloxane, alkylphenylsiloxane, an organic polymer having a silyl group (e.g., silyl polyether, silyl acrylate), polyisobutylene having a silyl group, etc. Examples of the silane crosslinking agent include alkoxy-functional silane, oximosilane, acetoxysilane, enoxysilane, etc. Examples of the filler include iron oxide, titanium dioxide, carbon black, talc, etc. Examples of the condensation catalyst include titanate, zirconate, etc. These condensation curable silyl-terminated polymer, silane crosslinking agent, condensation catalyst, and filler are stored in a state divided into a first liquid and a second liquid in a combination where the curing reaction does not proceed, and are mixed at the time of use. Examples of the two-component curable silicone include those described in Japanese Patent Application Laid-Open No. 2018-503725 and Japanese Patent Application Laid-Open No. 2022-550962. As a commercially available product of the two-component curable silicone, for example, SST-2650 manufactured by Dow can be used.

[0033] In the above pneumatic tire, it is preferable that the glass transition temperature of the sealant in the sealant layer 20 is in the range of -120°C to -40°C. By using a sealant with a low glass transition temperature, it is possible to ensure good puncture sealing performance in a low-temperature environment. If the glass transition temperature of the sealant is higher than -40°C, the puncture sealing performance in a low-temperature environment will deteriorate.

[0034] In the pneumatic tire described above, as shown in FIG. 2, it is preferable that the thickness S of the sealant layer 20 is in the range of 2.0 mm to 5.0 mm. Thereby, while ensuring puncture sealing performance, it is possible to suppress deterioration of rolling resistance due to an increase in tire weight, and to suppress uneven distribution of the sealant layer 20 caused by the flow of the sealant. Here, if the thickness S of the sealant layer 20 is less than 2.0 mm, the puncture sealing performance will deteriorate. Conversely, if it is greater than 5.0 mm, the rolling resistance will deteriorate due to an increase in tire weight, and uneven distribution of the sealant layer 20 may occur due to the flow of the sealant. The thickness S of the sealant layer 20 is the overall average thickness. Such an average thickness of the sealant layer 20 can be calculated, for example, by taking CT scans of the tire meridian cross-section at 8 locations on the tire circumference, and measuring the thickness of the sealant layer 20 at 5 points in each of the captured images, namely, the tire equator position, the outer edge positions (both sides) 10 mm inward in the tire width direction from the edge of the sealant layer 20, and the intermediate positions (both sides) between the tire equator position and the outer edge positions, and then calculating from the measured values at a total of 40 points.

[0035] In the pneumatic tire described above, as shown in FIG. 3, when a belt layer 7 (7A, 7B) including belt cords inclined in the tire circumferential direction is embedded in the tread portion 1, it is preferable that the inclination direction of the sealant strip 21 in the tire circumferential direction is opposite to the inclination direction of the belt cords of the belt layer 7A located at the innermost side in the tire radial direction in the tire circumferential direction. In a pneumatic tire, ply steer occurs due to the orientation of the belt cords of the belt layer 7, and the orientation of the sealant strip 21 also becomes a factor in ply steer. Therefore, by making the inclination direction of the sealant strip 21 in the tire circumferential direction opposite to the inclination direction of the belt cords of the belt layer 7A located at the innermost side in the tire radial direction in the tire circumferential direction, it is possible to reduce ply steer.

[0036] In the above pneumatic tire, as shown in Fig. 1, it is preferable that the width Ws of the sealant layer 20 is 90% or more of the width Wb of the belt layer 7A located at the innermost side in the tire radial direction. In particular, it is preferable that the end portion of the sealant layer 20 is disposed outside the end portion of the belt layer 7A located at the innermost side in the tire radial direction in the tire width direction. By making the width Ws of the sealant layer 20 sufficiently larger than the width Wb of the belt layer 7A, it is possible to effectively prevent a puncture of the pneumatic tire. Here, if the width Ws of the sealant layer 20 is smaller than 90% of the width Wb of the belt layer 7A, the puncture sealing property deteriorates.

[0037] For the same reason, when a belt cover layer 8 including an organic fiber cord oriented in the tire circumferential direction is embedded on the outer peripheral side of the belt layer 7 in the tread portion 1, it is preferable that the end portion of the sealant layer 20 is disposed outside the end portion of the belt cover layer 8 in the tire width direction. By making the width of the sealant layer 20 sufficiently large, it is possible to effectively prevent a puncture of the pneumatic tire.

[0038] In the above pneumatic tire, as shown in Fig. 2, at all locations of the belt layer 7A located at the innermost side in the tire radial direction, it is preferable that the distance (shortest distance) L from the belt layer 7A to the sealant layer 20 is 10 mm or less. Thereby, when a foreign object such as a nail penetrates the tread portion 1, the sealant easily flows to the belt layer 7A, so that good puncture sealing property can be ensured. If there is a portion where the distance L from the belt layer 7A to the sealant layer 20 is larger than 10 mm, the puncture sealing property in that portion may become insufficient.

[0039] In the above pneumatic tire, it is preferable that the ratio of the thickness S of the sealant layer 20 to the distance L from the belt layer 7A located at the innermost side in the tire radial direction to the sealant layer 20 satisfies the relationship of S / L ≧ 0.3. By making the thickness S of the sealant layer 20 sufficiently larger than the distance L, good puncture sealing property can be ensured. If the ratio S / L is smaller than 0.3, the puncture sealing property deteriorates.

[0040] FIG. 6 shows a pneumatic tire according to another embodiment of the present invention. In FIG. 6, a sound-absorbing material 40 is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer 20. The sound-absorbing material 40 is composed of a porous material having continuous bubbles and has predetermined sound-absorbing characteristics based on the porous structure. It is preferable to use foamed polyurethane as the porous material of the sound-absorbing material 40. The sound-absorbing material 40 is adhered onto the sealant layer 20 based on the adhesiveness of the sealant layer 20 after the formation of the sealant layer 20. In this case, since the sound-absorbing material 40 is installed with respect to the sealant layer 20 applied at a low temperature, damage to the sound-absorbing material 40 can be avoided and its sound-absorbing effect can be maintained well.

Example

[0041] In a pneumatic tire having a tire size of 255 / 45R19 and including a tread portion, a pair of sidewall portions, and a pair of bead portions, a sealant layer having a structure in which a sealant strip is spirally arranged along the tire circumferential direction on the inner surface of the tire in the tread portion is formed, and the constituent material of the sealant layer, the thickness S of the sealant layer, the ratio of the width of the sealant layer to the width of the belt layer, the inclination direction of the sealant strip, the distance L from the belt layer located at the innermost side in the tire radial direction to the sealant layer, and S / L were varied as shown in Table 1 to produce tires of Comparative Example 1 and Examples 1 to 6. Also, a tire of a conventional example having no sealant layer on the inner surface of the tire in the tread portion was prepared.

[0042] Regarding the inclination direction of the sealant strip, when the inclination direction of the sealant strip with respect to the tire circumferential direction is in the same phase as the inclination direction of the belt cord of the belt layer located at the innermost side in the tire radial direction with respect to the tire circumferential direction, it is indicated as "same", and when the inclination direction of the sealant strip with respect to the tire circumferential direction is in the opposite phase to the inclination direction of the belt cord of the belt layer located at the innermost side in the tire radial direction with respect to the tire circumferential direction, it is indicated as "reverse".

[0043] For these test tires, the rolling resistance, ply steer, and puncture sealing performance were evaluated by the following test methods, and the results are shown together in Table 1.

[0044] Rolling resistance: Each test tire was assembled onto a wheel with a rim size of 19×8.5J, mounted on a rolling resistance tester, and the rolling resistance was measured in accordance with JIS-D4234 with an air pressure of 210 kPa. The evaluation results were shown as an index with the reciprocal of the measured value and the conventional example set as 100. The larger this index value, the smaller the rolling resistance.

[0045] Pull-steer: Each test tire was assembled onto a wheel with a rim size of 19×8.5J, mounted on a uniformity tester, and the pull-steer was measured in accordance with JIS-D4233 with an air pressure of 200 kPa. The evaluation results were shown as an index with the reciprocal of the measured value and the conventional example set as 100. The larger this index value, the smaller the pull-steer.

[0046] Puncture sealability: Each test tire was assembled onto a wheel with a rim size of 19×8.5J, with an initial air pressure of 250 kPa. A nail with a diameter of 4.0 mm was driven into the tread part, and after leaving the tire for 1 hour with the nail pulled out, the air pressure was measured again, and the pressure drop rate relative to the initial air pressure was determined. The evaluation results were indicated as "◎" when the pressure drop rate was 2% or less, "○" when the pressure drop rate was more than 2% and 7% or less, "△" when the pressure drop rate was more than 7% and 20% or less, and "×" when the pressure drop rate was more than 20%.

[0047]

Table 1

[0048] As can be seen from Table 1, the tires of Examples 1 to 6 all had good puncture sealing performance. In contrast, for the tire of Comparative Example 1, when forming a sealant layer having a structure in which the strip material of the sealant is arranged spirally along the tire circumferential direction, a sealant mainly composed of butyl rubber is used. Therefore, the integrity between the circumferential portions of the sealant strip material is not good, and as a result, the sealing performance by the sealant layer is insufficient.

Explanation of Reference Numerals

[0049] 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 10 Inner surface of tire 20 Sealant layer 21 Strip material of sealant 40 Sound absorbing material

Claims

1. In a pneumatic tire having a tread portion that extends in the tire circumferential direction and forms 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 inner side in the tire radial direction of these sidewall portions, a sealant layer having a structure in which a sealant strip is spirally disposed along the tire circumferential direction on the inner surface of the tire in the tread portion is formed, and the sealant is composed of a silicone-based composition, a belt layer including a belt cord inclined with respect to the tire circumferential direction is embedded in the tread portion, and the inclination direction of the sealant strip with respect to the tire circumferential direction is opposite in phase to the inclination direction of the belt cord of the belt layer located at the innermost side in the tire radial direction. The pneumatic tire is characterized by this.

2. The pneumatic tire according to claim 1, wherein the silicone-based composition is a two-component curable silicone.

3. The pneumatic tire according to claim 1 or 2, wherein the glass transition temperature of the sealant is in the range of -120°C to -40°C.

4. The pneumatic tire according to claim 1 or 2, wherein the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm.

5. A belt layer including a belt cord inclined with respect to the tire circumferential direction is embedded in the tread portion, and the width of the sealant layer is 90% or more of the width of the belt layer located at the innermost side in the tire radial direction. The pneumatic tire according to claim 1 or 2 is characterized by this.

6. The pneumatic tire according to claim 5, wherein the end portion of the sealant layer is disposed outside the end portion of the belt layer located at the innermost side in the tire radial direction in the tire width direction.

7. A belt cover layer including an organic fiber cord oriented in the tire circumferential direction on the outer peripheral side of the belt layer is embedded in the tread portion, and the end portion of the sealant layer is disposed outside the end portion of the belt cover layer in the tire width direction. The pneumatic tire according to claim 6 is characterized by this.

8. The pneumatic tire according to claim 1 or 2, wherein at all locations of the belt layer located at the innermost side in the tire radial direction, the distance L from the belt layer to the sealant layer is 10 mm or less.

9. The pneumatic tire according to claim 8, characterized in that the ratio of the thickness S of the sealant layer to the distance L from the belt layer located at the innermost side in the tire radial direction to the sealant layer satisfies the relationship S / L≥0.

3.

10. The pneumatic tire according to claim 1 or 2, characterized in that a sound-absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer.

11. In a pneumatic tire including a tread portion that extends in the tire circumferential direction and forms 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 inner side in the tire radial direction of these sidewall portions, a sealant layer having a structure in which a strip material of a sealant is spirally disposed along the tire circumferential direction on the inner surface of the tire in the tread portion is formed, and the sealant is composed of a silicone-based composition, a belt layer including a belt cord inclined with respect to the tire circumferential direction is embedded in the tread portion, the width of the sealant layer is 90% or more of the width of the belt layer located at the innermost side in the tire radial direction, and the end portion of the sealant layer is disposed on the outer side in the tire width direction than the end portion of the belt layer located at the innermost side in the tire radial direction, a belt cover layer including an organic fiber cord oriented in the tire circumferential direction is embedded on the outer peripheral side of the belt layer in the tread portion, and the end portion of the sealant layer is disposed on the outer side in the tire width direction than the end portion of the belt cover layer. The pneumatic tire is characterized by this.

12. A method for manufacturing a pneumatic tire according to claim 1 or 11, after manufacturing a pneumatic tire excluding the sealant layer, when forming the sealant layer by applying a sealant composed of a silicone-based composition to the inner surface of the tire in the tread portion, the temperature of the sealant applied to the inner surface of the tire is made lower than 70°C. The method for manufacturing a pneumatic tire is characterized by this.

13. The method for manufacturing a pneumatic tire according to claim 12, characterized in that a sound-absorbing material is installed along the tire circumferential direction on the inner side in the tire radial direction of the sealant layer.

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