Pneumatic tire and method of manufacturing the same

Abstract

Provided is a pneumatic tire capable of maintaining the sealability achieved by a sealant layer well and further capable of suppressing peeling of the sealant layer, and a manufacturing method therefor. A plurality of belt layers (7) including belt cords inclined with respect to the tire circumferential direction and arranged so as to cross each other in the layer direction are embedded in a tread portion (1), the belt layers (7) include a first belt layer (7A) located on the radially innermost side and a second belt layer (7B) located on the outer side thereof, a sealant layer (20) in which a sealant tape (21) in which a sealant composed of a silicone-based composition is arranged in a spiral along the tire circumferential direction is formed on the inner surface (10) of the tire at the tread portion (1), in the case where an angle (θ) formed by the belt cords of the first belt layer (7A) and the second belt layer (7B) is 110° or less, the inclined direction of the sealant tape (21) is the same direction as the inclined direction of the belt cords of the first belt layer (7A), and in the case where the angle (θ) exceeds 110°, the inclined direction of the sealant tape (21) is the opposite direction to the inclined direction of the belt cords of the first belt layer (7A).

Description

Technical Field

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire at the tread portion and a method for manufacturing the same, and more specifically, to a pneumatic tire and a method for manufacturing the same, which are capable of maintaining the sealing performance achieved by the sealant layer and thus inhibiting the peeling of the sealant layer. Background Technology

[0002] In pneumatic tires, a solution has been proposed to place a sealant layer on the radially inner side of the inner liner at the tread level. In such a pneumatic tire, when a foreign object such as a nail pierces the tread, the sealant flows into the penetration hole, thereby suppressing the decrease in air pressure and maintaining driving stability.

[0003] Conventionally, the sealant constituting the sealant layer is typically a rubber composition primarily composed of butyl rubber (see, for example, Patent Documents 1-3). Examples of butyl rubbers include, in addition to butyl rubber (IIR), halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR). Such sealants are applied to the inner surface of the tire in a softened state after being heated to a high temperature (see, for example, Patent Document 4). More specifically, a sealant layer is formed by spirally arranging a strip of sealant in a softened state along the tire circumference on the inner surface of the tire.

[0004] However, in a sealant layer formed as described above, the sealant cools before the surrounding portions of the sealant strip fuse together. Therefore, the integrity of the surrounding portions of the sealant strip is poor, resulting in insufficient sealing performance. Furthermore, if the surrounding portions of the sealant strip are not sufficiently integrated, the sealant layer tends to flow towards the center of the tread due to the centrifugal force generated during tire rotation, which is also a major cause of reduced sealing performance.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 6583456

[0008] Patent Document 2: Japanese Patent No. 6620851

[0009] Patent Document 3: Japanese Patent No. 7319533

[0010] Patent Document 4: Japanese Patent No. 6124967 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The purpose of this invention is to provide a pneumatic tire and a method for manufacturing the same, which can effectively maintain the sealing performance achieved by the sealant layer and thus inhibit the peeling of the sealant layer.

[0013] Methods for solving problems

[0014] The pneumatic tire of the present invention for achieving the above-mentioned objective comprises: a tread portion extending in a ring shape along the tire circumference; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed radially inside the sidewall portions, characterized in that...

[0015] The tread portion has multiple belt layers embedded therein, each belt layer comprising belt cords inclined relative to the tire circumference and arranged such that the belt cords intersect each other between the layers. The multiple belt layers include a first belt layer located radially innermost on the tire and a second belt layer located outermost on the first belt layer.

[0016] A sealant layer is formed on the inner surface of the tire at the tread area. This sealant layer has a structure in which sealant strips are arranged in a spiral along the tire circumference. The sealant is composed of an organosilicon-based composition.

[0017] When the angle between the belt cords of the first belt layer and the belt cords of the second belt layer is less than 110°, the inclination direction of the sealant strip relative to the tire circumference is the same as the inclination direction of the belt cords of the first belt layer relative to the tire circumference. When the angle between the belt cords of the first belt layer and the belt cords of the second belt layer exceeds 110°, the inclination direction of the sealant strip relative to the tire circumference is opposite to the inclination direction of the belt cords of the first belt layer relative to the tire circumference.

[0018] The method for manufacturing a pneumatic tire according to the present invention for achieving the above-mentioned objective is characterized in that,

[0019] After manufacturing the pneumatic tire, excluding the sealant layer...

[0020] When a sealant composed of an organosilicon composition is applied to the inner surface of the tire at the tread area to form the sealant layer, the temperature of the sealant applied to the inner surface of the tire is kept below 70°C.

[0021] Invention Effects

[0022] In this invention, a sealant layer is formed on the inner surface of the tire at the tread level. This sealant layer has a structure in which the sealant strips are arranged in a spiral along the tire circumference. The sealant is composed of an organosilicon composition. Therefore, during the curing reaction of the organosilicon composition, the surrounding portions of the sealant strips easily fuse together, resulting in good integration between the surrounding portions and thus improving the sealing performance achieved by the sealant layer. Furthermore, because the surrounding portions of the sealant strips are well integrated, the sealant layer is less likely to flow towards the center of the tire width due to centrifugal force generated during tire rotation, which also contributes to improved sealing performance. Moreover, the sealant composed of an organosilicon composition can be applied at low temperatures; for example, the temperature of the sealant applied to the inner surface of the tire can be below 70°C. Therefore, it also has the advantage of reducing the impact of heat on the tire and preventing deterioration of tire performance.

[0023] Furthermore, when the angle between the belt cords of the first belt layer and the belt cords of the second belt layer is 110° or less, the inclination direction of the sealant strip relative to the tire circumference is the same as the inclination direction of the belt cords of the first belt layer relative to the tire circumference. When the angle between the belt cords of the first belt layer and the belt cords of the second belt layer exceeds 110°, the inclination direction of the sealant strip relative to the tire circumference is opposite to the inclination direction of the belt cords of the first belt layer relative to the tire circumference. Therefore, the shear force applied to the sealant layer due to the angle change of the belt cords at ground contact can be reduced. As a result, sealant layer peeling can be suppressed.

[0024] In this invention, it is preferred that the organosilicon composition is a two-component curable organosilicon. Two-component curable organosilicon has a low viscosity immediately after mixing, thus allowing for coating even at low temperatures.

[0025] In this invention, it is preferred that the glass transition temperature of the sealant is in the range of -120°C to -40°C. By using a sealant with a low glass transition temperature, puncture seal performance can be well ensured in low-temperature environments.

[0026] In this invention, it is preferred that the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm. This ensures puncture resistance while suppressing the deterioration of rolling resistance caused by increased tire weight, and also suppresses unevenness of the sealant layer caused by sealant flow.

[0027] In this invention, it is preferable that the width of the sealant layer is 90% or more of the width of the first belt layer. Particularly preferably, the end of the sealant layer is positioned further outward in the tire width direction than the end of the first belt layer. By sufficiently increasing the width of the sealant layer, punctures in the pneumatic tire can be effectively prevented.

[0028] In this invention, it is preferable that, when a belt cover layer comprising organic fiber cords oriented circumferentially along the tire circumferential direction is embedded on the outer periphery of the belt layer at the tread portion, the end of the sealant layer is positioned further outward in the tire width direction than the end of the belt cover layer. By sufficiently increasing the width of the sealant layer, punctures to the pneumatic tire can be effectively prevented.

[0029] In this invention, it is preferable that the distance L from the first belt layer to the sealant layer is less than 10 mm at all locations of the first belt layer. This allows the sealant to flow easily into the belt layer when a foreign object such as a nail penetrates the tread, thus ensuring good puncture seal.

[0030] In this invention, it is preferable that the ratio of the thickness S of the sealant layer to the distance L from the first belt layer to the sealant layer satisfies the relationship S / L≥0.3. By making the thickness S of the sealant layer sufficiently large relative to the distance L, good puncture seal performance can be ensured.

[0031] In this invention, it is preferable that a sound-absorbing element is provided along the tire circumference on the radially inner side of the sealant layer. In this case, the sound-absorbing element can be provided on the sealant layer after it has been applied at low temperatures, thus avoiding damage to the sound-absorbing element and maintaining its sound absorption effect well. Attached Figure Description

[0032] Figure 1 This is a meridional sectional view showing an inflatable tire constructed according to an embodiment of the present invention.

[0033] Figure 2 It means Figure 1 A cross-sectional view of the main parts of an inflatable tire.

[0034] Figure 3 It means Figure 1 A plan view of the belt layer, belt cover layer, and sealant layer of an inflatable tire.

[0035] Figure 4 It means Figure 1 Plan view of other forms of belt layer, belt cover layer and sealant layer of pneumatic tire.

[0036] Figure 5 It means Figure 1 A cross-sectional view of the manufacturing method of a pneumatic tire.

[0037] Figure 6 It means in Figure 1 A plan view of the sealant layer formed on the inner surface of the tire at the tread area of ​​an inflatable tire.

[0038] Figure 7 This is a meridional sectional view showing an inflatable tire constructed according to other embodiments of the present invention. Detailed Implementation

[0039] The structure of the present invention will now be described in detail with reference to the accompanying drawings. Figures 1-4 This refers to an inflatable tire constructed according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the pneumatic tire of this embodiment includes a tread portion 1 that extends in the circumferential direction of the tire and is in the shape of 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 radially inner side of these sidewall portions 2.

[0041] A carcass layer 4 is provided between a pair of bead portions 3, 3. The carcass layer 4 includes multiple carcass cords extending radially along the tire and folding back from the inside to the outside of the tire around the bead core 5 disposed in each bead portion 3. A bead filler 6 with a triangular cross-section and made of rubber composition is disposed on the outer periphery of the bead core 5.

[0042] On the other hand, multiple belt layers 7 are embedded on the outer periphery of the carcass layer 4 at the tread portion 1. These belt layers 7 contain multiple belt cords inclined relative to the tire circumference and are arranged in a manner where the belt cords intersect each other between layers. The multiple belt layers 7 include a first belt layer 7A located on the innermost radial side of the tire and a second belt layer 7B located on the outer side of the first belt layer 7A, wherein 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 belt cords relative to the tire circumference is set, for example, in the range of 10° to 70°. Particularly in the case of passenger car tires, the inclination angle of the belt cords relative to the tire circumference is set, for example, in the range of 10° to 40°. Steel cords are preferably used as the belt cords of the belt layers 7.

[0043] On the outer periphery of the belt layer 7, for the purpose of improving high-speed durability, at least one belt cover layer 8 is provided, in which reinforcing cords are arranged at an angle of, for example, 5° or less relative to the tire circumference. This belt cover layer 8 is preferably a seamless structure obtained by continuously winding a strip, formed by straightening at least one reinforcing cord and coating it with rubber, at a substantially 0° angle relative to the tire circumference. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon or polyethylene terephthalate (PET) are preferably used.

[0044] Furthermore, the above-described internal tire structure illustrates a representative example of a pneumatic tire, but is not limited thereto. Various grooves, including multiple main grooves 11 extending along the tire circumference, are formed in the tread portion 1.

[0045] In the aforementioned pneumatic tire, a sealant layer 20 is formed continuously along the tire circumference on the inner surface 10 of the tread portion 1. Preferably, the center of the sealant layer 20 in the tire width direction coincides with the tire equator, but its center position can also be offset from the tire equator towards either side in the tire width direction. The distance between the center of the sealant layer 20 in the tire width direction and the tire equator in the tire width direction is preferably 10 mm or less, more preferably 5 mm or less. Therefore, the sealant layer 20 will not adversely affect tire balance. Figure 3 or Figure 4 As shown, the sealant layer 20 has a structure in which the sealant strip 21 is arranged in a spiral along the circumference of the tire. The sealant of the sealant layer 20 is composed of an organosilicon-based composition. The organosilicon-based composition comprises a synthetic polymer compound having a main framework realized by siloxane bonds.

[0046] In the aforementioned pneumatic tire, when the angle θ between the belt cords of the first belt layer 7A and the belt cords of the second belt layer 7B is 110° or less, such as Figure 3 As shown, the inclination direction of the sealant strip 21 relative to the tire circumference is set to the same direction as the inclination direction of the belt cords of the first belt layer 7A relative to the tire circumference. Furthermore, when the angle θ between the belt cords of the first belt layer 7A and the belt cords of the second belt layer 7B exceeds 110°, as... Figure 4 As shown, the inclination direction of the sealant strip 21 relative to the tire circumference is set to be opposite to the inclination direction of the belt cords of the first belt layer 7A relative to the tire circumference. That is, according to the inventors' understanding, when the angle θ is less than 110°, an angle change occurs during ground contact, such that the cord angle of the first belt layer 7A decreases; on the other hand, when the angle θ exceeds 110°, an angle change occurs during ground contact, such that the cord angle of the first belt layer 7A increases. Therefore, by adapting the inclination direction of the sealant strip 21 relative to the tire circumference according to the angular change conceived during ground contact, the shear force applied to the sealant layer 20 during ground contact can be reduced. This, in turn, suppresses peeling of the sealant layer 20.

[0047] The pneumatic tire described above can be manufactured by the following method. First, a pneumatic tire is manufactured as described above, having a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3, and having a belt layer 7 and a belt cover layer 8 embedded in the tread portion 1. Next, a sealant layer 20 is formed by coating the inner surface 10 of the tire at the tread portion 1 with a sealant composed of an organosilicon-based composition.

[0048] Figure 5 express Figure 1 The specific manufacturing method of pneumatic tires, Figure 6 This refers to the sealant layer formed on the inner surface of the tire at the tread area. Figure 5 In this process, the sealant extrusion device 31 mixes the sealant supplied from pumps 32 and 33, and continuously discharges the mixed sealant as a strip 21 from nozzle 34. The sealant extrusion device 31 is configured to allow the nozzle 34 to be freely repositioned. Therefore, by rotating the tire while moving the nozzle 34 axially from a position where the nozzle 34 is close to the inner surface 10 of the tire, the sealant strip 21 can be arranged in a spiral shape on the inner surface 10 of the tire while being inclined relative to the tire circumferential direction Tc (see reference). Figure 6 The spirally arranged strips 21 of sealant are tightly adhered to each other (closely sealed). In this way, the spirally arranged strips 21 of sealant are integrated to form a sealant layer 20.

[0049] In the aforementioned pneumatic tire, a sealant layer 20 is formed on the inner surface 10 of the tire at the tread portion 1. This sealant layer 20 has a structure in which sealant strips 21 are arranged in a spiral along the tire circumference. The sealant is composed of an organosilicon-based composition. Therefore, during the curing reaction process of the organosilicon-based composition, the surrounding portions of the sealant strips 21 easily fuse together, resulting in good integration between the surrounding portions of the sealant strips 21. This improves the sealing performance achieved by the sealant layer 20. Furthermore, because the surrounding portions of the sealant strips 21 are well integrated, the sealant layer 20 is less likely to flow towards the center of the tire width direction due to centrifugal force generated during tire rotation, which also contributes to improved sealing performance. Moreover, using an organosilicon-based composition as the sealant for the sealant layer 20 also offers advantages such as excellent weather resistance and low temperature dependence of physical properties.

[0050] The silicone-based composition exhibits good flowability even at low temperatures, therefore, it is preferable to keep the temperature of the sealant applied to the inner surface 10 of the tire below 70°C. This reduces the impact of heat on the tire and prevents deterioration of tire performance. If the temperature is above 70°C, the impact of heat on the tire increases, becoming a major cause of tire performance deterioration. It is particularly preferable that the temperature of the sealant applied to the inner surface 10 of the tire is below 35°C. Furthermore, from the viewpoint of the flowability of the silicone-based composition, a lower limit of 20°C for the temperature of the sealant applied to the inner surface 10 of the tire is preferable.

[0051] The silicone-based composition used as the sealant constituting the sealant layer 20 can be a one-component curable silicone or a two-component curable silicone, but a two-component curable silicone is particularly preferred. Examples of one-component curable silicones include moisture-curing silicones. Two-component curable silicones consist of a first component and a second component; the curing reaction begins by mixing these components, ensuring the stability of the sealant layer 20 after curing. In the above apparatus, the first and second components of the two-component curable silicone are supplied from pumps 32 and 33, respectively. Because the two-component curable silicone has a low viscosity immediately after mixing, it can be applied even at low temperatures. It is particularly preferred that the two-component curable silicone has a curing period of 5 days or more until complete curing.

[0052] Two-component curable silicones are, for example, composed of a condensation-curable silyl-terminated polymer, a silane crosslinking agent, a condensation catalyst, and a filler. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers containing silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylene containing silyl groups. Examples of silane crosslinking agents include alkoxy-functionalized silanes, oxime silanes, 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 crosslinking agents, condensation catalysts, and fillers are stored separately as component 1 and component 2 in a combination that does not undergo a curing reaction, and are mixed before use. Examples of two-component curable silicones include those described in Japanese Patent Publication No. 2018-503725 and Japanese Patent Publication No. 2022-550962. Commercially available two-component curable silicones include, for example, SST-2650 manufactured by Dow Chemical Company.

[0053] In the aforementioned pneumatic tire, the glass transition temperature of the sealant in the sealant layer 20 is preferably in the range of -120°C to -40°C. By using a sealant with a low glass transition temperature, puncture sealing performance in low-temperature environments can be well ensured. If the glass transition temperature of the sealant is higher than -40°C, the puncture sealing performance in low-temperature environments will decrease.

[0054] In the aforementioned pneumatic tires, such as Figure 2As shown, the thickness S of the sealant layer 20 is preferably in the range of 2.0 mm to 5.0 mm. This ensures puncture resistance while suppressing the deterioration of rolling resistance caused by increased tire weight and suppressing non-uniformity of the sealant layer 20 caused by sealant flow. If the thickness S of the sealant layer 20 is less than 2.0 mm, the puncture resistance decreases; conversely, if it is greater than 5.0 mm, the increased tire weight leads to worsened rolling resistance, and non-uniformity of the sealant layer 20 may occur due to sealant flow. The thickness S of the sealant layer 20 is the overall average thickness. This average thickness of the sealant layer 20 can be measured, for example, by taking CT scans of the tire's radial cross-section at eight locations on the tire circumference. In each image, the thickness of the sealant layer 20 is measured at five points: the tire equator, the outer edge (10 mm inward from the edge of the sealant layer 20 in the tire width direction) on both sides, and the midpoint between the tire equator and the outer edge (on both sides). The thickness is calculated based on the measurements taken at a total of 40 points.

[0055] In the aforementioned pneumatic tires, such as Figure 1 As shown, the width Ws of the sealant layer 20 is preferably 90% or more of the width Wb of the first belt layer 7A located at the innermost radial side of the tire. In particular, the end of the sealant layer 20 is preferably positioned further outward in the tire width direction than the end of the first belt layer 7A located at the innermost radial side of the tire. By making the width Ws of the sealant layer 20 sufficiently large relative to the width Wb of the belt layer 7A, punctures to the pneumatic tire can be effectively prevented. Here, if the width Ws of the sealant layer 20 is less than 90% of the width Wb of the first belt layer 7A, the puncture resistance is reduced.

[0056] For the same reason, when a belt cover layer 8 containing organic fiber cords oriented circumferentially along the tire circumferential direction is embedded on the outer periphery of the belt cover layer 7 at the tread 1, the end of the sealant layer 20 is preferably positioned further outward in the tire width direction than the end of the belt cover layer 8. By making the width of the sealant layer 20 sufficiently large, punctures to the pneumatic tire can be effectively prevented.

[0057] In the aforementioned pneumatic tires, such as Figure 2 As shown, in all locations of the first belt layer 7A located on the innermost radial side of the tire, the shortest distance L from the first belt layer 7A to the sealant layer 20 should preferably be less than 10 mm. This allows the sealant to flow easily into the first belt layer 7A when a foreign object such as a nail penetrates the tread portion 1, thus ensuring good puncture seal. If there are portions where the distance L from the first belt layer 7A to the sealant layer 20 is greater than 10 mm, the puncture seal at those portions may be insufficient.

[0058] In the aforementioned pneumatic tire, the ratio of the thickness S of the sealant layer 20 to the distance L from the first belt layer 7A located at the innermost radial side of the tire to the sealant layer 20 should preferably satisfy a relationship of S / L ≥ 0.3. By making the thickness S of the sealant layer 20 sufficiently large relative to the distance L, good puncture seal performance can be ensured. If the ratio S / L is less than 0.3, the puncture seal performance is reduced.

[0059] Figure 7 This refers to a pneumatic tire constructed according to other embodiments of the present invention. Figure 7 In this embodiment, a sound-absorbing element 40 is provided along the tire circumference on the radially inner side of the sealant layer 20. The sound-absorbing element 40 is made of a porous material with continuous air bubbles and has predetermined sound-absorbing characteristics based on this porous structure. Foamed polyurethane is preferably used as the porous material for the sound-absorbing element 40. After the sealant layer 20 is formed, the sound-absorbing element 40 is adhered to the sealant layer 20 based on its adhesiveness. In this case, since the sound-absorbing element 40 is provided on the sealant layer 20 after it has been coated at low temperatures, damage to the sound-absorbing element 40 can be avoided, and its sound-absorbing effect can be well maintained.

[0060] Example

[0061] Tires for Comparative Examples 1-2 and Examples 1-5 were manufactured as follows: In a pneumatic tire with a tire size of 255 / 45R19 and having a tread, a pair of sidewalls, and a pair of bead portions, a sealant layer with a sealant strip arranged in a spiral along the tire circumference was formed on the inner surface of the tire at the tread. 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 radial side of the tire to the sealant layer, and the ratio S / L were varied as shown in Table 1. Additionally, a conventional tire of Example 1, which did not have a sealant layer on the inner surface of the tire at the tread, was prepared. The angle θ (crossing angle of the belt cords) between the belt cords of the first belt layer and the belt cords of the second belt layer is shown in Table 1.

[0062] Regarding the tilt direction of the sealant strip, the case where the tilt direction of the sealant strip relative to the tire circumference is in the same phase as the tilt direction of the belt cord of the innermost belt layer relative to the tire circumference is described as "same"; the case where the tilt direction of the sealant strip relative to the tire circumference is in the opposite phase to the tilt direction of the belt cord of the innermost belt layer relative to the tire circumference is described as "opposite".

[0063] For these test tires, rolling resistance, peel strength, and puncture seal were evaluated using the following test methods, and the results are shown in Table 1.

[0064] Rolling resistance:

[0065] Each test tire was assembled onto a wheel with a rim size of 19×8.5J and mounted on a rolling resistance testing machine. The air pressure was set to 210 kPa, and the rolling resistance was measured according to JIS-D4234. The evaluation results were expressed as the reciprocal of the measured value, with the previous example 1 set to 100. The larger the index value, the smaller the rolling resistance.

[0066] Peelability:

[0067] Each test tire was assembled onto a 19×8.5J rim and mounted on an indoor drum testing machine (drum diameter 1707mm). Under conditions of ambient temperature controlled at 38±3℃, air pressure set at 120kPa, load set at 120% of maximum load capacity, and speed set at 80km / h, the tires were driven for 6000km. The sealant layer on the inner surface of the tires was then observed. The evaluation results are expressed as "". "Indicates that the sealant layer has not floated or shifted, use " "This indicates that the sealant layer has not lifted and the offset is less than 5cm, indicated by " This indicates that the sealant layer has floated or shifted by more than 5cm.

[0068] Puncture seal:

[0069] Each test tire was assembled onto a wheel with a rim size of 19×8.5J, and the initial air pressure was set to 250 kPa. A 4.0 mm diameter nail was driven into the tire tread. After removing the nail, the tire was left to stand for 1 hour, and the air pressure was measured again. The pressure drop rate relative to the initial air pressure was calculated. The evaluation results are expressed as "". "" indicates a pressure drop rate of less than 2%, indicated by " "" indicates a pressure drop rate exceeding 2% but below 7%, indicated by " "" indicates a pressure drop rate exceeding 7% but below 20%, indicated by " "This indicates a situation where the rate of pressure reduction exceeds 20%."

[0070] [Table 1]

[0071]

[0072] As shown in Table 1, the tires of Examples 1-5 all exhibited good puncture resistance. In contrast, in the tire of Comparative Example 1, because a butyl rubber-based sealant was used when forming the sealant layer with the sealant strip arranged spirally along the tire circumference, the integrality of the surrounding portions of the sealant strip was poor, resulting in insufficient sealing performance achieved by the sealant layer. In the tire of Comparative Example 2, when the angle θ between the belt cords of the first belt layer and the belt cords of the second belt layer was 110° or less, the inclination direction of the sealant strip relative to the tire circumference was opposite to the inclination direction of the belt cords of the first belt layer relative to the tire circumference. Therefore, compared to Examples 1-5, the peelability of the sealant layer was slightly reduced.

[0073] Next, tires of Comparative Examples 11-12 and Examples 11-15 were manufactured: In a pneumatic tire with a tire size of 255 / 45R19 and having a tread, a pair of sidewalls, and a pair of bead portions, a sealant layer with a sealant strip arranged in a spiral along the tire circumference was formed on the inner surface of the tire at the tread. 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 radial side of the tire to the sealant layer, and the ratio S / L were varied as shown in Table 2. Additionally, a tire of Conventional Example 11, which did not have a sealant layer on the inner surface of the tire at the tread, was prepared. The angle θ (crossing angle of the belt cords) between the belt cords of the first belt layer and the belt cords of the second belt layer is shown in Table 2.

[0074] For these test tires, rolling resistance, peel strength, and puncture seal were evaluated using the test methods described above, and the results are shown in Table 2. The evaluation standard for rolling resistance is the same as that of Example 11.

[0075] [Table 2]

[0076]

[0077] As shown in Table 2, the tires of Examples 11-15 all exhibited good puncture resistance. In contrast, in the tire of Comparative Example 11, because a butyl rubber-based sealant was used when forming the sealant layer with the sealant strip arranged spirally along the tire circumference, the integrality of the surrounding portions of the sealant strip was poor, resulting in insufficient sealing performance achieved by the sealant layer. In the tire of Comparative Example 12, when the angle θ between the belt cords of the first belt layer and the belt cords of the second belt layer exceeded 110°, the inclination direction of the sealant strip relative to the tire circumference was the same as the inclination direction of the belt cords of the first belt layer relative to the tire circumference. Therefore, compared to Examples 11-15, the peelability of the sealant layer was slightly reduced.

[0078] Explanation of reference numerals in the attached figures

[0079] 1. Fetal face

[0080] 2. Side of the tire

[0081] 3. Bead area

[0082] 4. Fetal body layers

[0083] 5. Bead core

[0084] 6. Bead filling

[0085] 7. Belt layer

[0086] 8. Belt Covering Layer

[0087] 10. Inner surface of the tire

[0088] 20. Sealant layer

[0089] 21. Sealant strips

[0090] 40 sound absorbing parts

Claims

1. A pneumatic tire, comprising: a tread portion extending in a ring shape along the tire circumference; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed radially inside the sidewall portions, characterized in that, The tread portion has multiple belt layers embedded therein, each belt layer comprising belt cords inclined relative to the tire circumference and arranged such that the belt cords intersect each other between the layers. The multiple belt layers include a first belt layer located radially innermost on the tire and a second belt layer located outermost on the first belt layer. A sealant layer is formed on the inner surface of the tire at the tread area. This sealant layer has a structure in which sealant strips are arranged in a spiral along the tire circumference. The sealant is composed of an organosilicon-based composition. When the angle between the belt cords of the first belt layer and the belt cords of the second belt layer is less than 110°, the inclination direction of the sealant strip relative to the tire circumference is the same as the inclination direction of the belt cords of the first belt layer relative to the tire circumference. When the angle between the belt cords of the first belt layer and the belt cords of the second belt layer exceeds 110°, the inclination direction of the sealant strip relative to the tire circumference is opposite to the inclination direction of the belt cords of the first belt layer relative to the tire circumference.

2. The pneumatic tire according to claim 1, characterized in that, The organosilicon composition is a two-component cured organosilicon.

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

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

5. The pneumatic tire according to claim 1 or 2, characterized in that, The width of the sealant layer is more than 90% of the width of the first belt layer.

6. The pneumatic tire according to claim 5, characterized in that, The end of the sealant layer is positioned further outward in the tire width direction than the end of the first belt layer.

7. The pneumatic tire according to claim 6, characterized in that, A belt cover layer comprising organic fiber cords oriented in the tire circumferential direction is embedded on the outer periphery of the belt layer at the tread area, and the end of the sealant layer is positioned outside the tire width direction than the end of the belt cover layer.

8. The pneumatic tire according to claim 1 or 2, characterized in that, At all locations of the first belt layer, the distance L from the first belt layer to the sealant layer is less than 10 mm.

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 first belt layer 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 element is provided along the tire circumference on the radial inner side of the sealant layer.

11. A method for manufacturing a pneumatic tire, wherein the method for manufacturing a pneumatic tire is a method for manufacturing the pneumatic tire according to any one of claims 1 to 9, characterized in that, After manufacturing the pneumatic tire, excluding the sealant layer... When a sealant composed of an organosilicon composition is applied to the inner surface of the tire at the tread area to form the sealant layer, the temperature of the sealant applied to the inner surface of the tire is kept below 70°C.

12. The method for manufacturing a pneumatic tire according to claim 11, characterized in that, A sound-absorbing element is provided along the tire circumference on the radially inner side of the sealant layer of the tire.

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