Pneumatic tire and method of manufacturing the same

Abstract

A pneumatic tire with a sealant layer on the inner surface of the tread portion that improves ride comfort is provided, and a method for manufacturing the same. In a pneumatic tire having a tread portion (1) extending in a ring shape along the tire circumference, 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 radially inner side of these sidewall portions (2), a sealant layer (20) is formed on the inner surface (10) of the tread portion (1). The sealant layer (20) has a structure in which sealant strips (21) are spirally arranged along the tire circumference. The starting point (P1) and the ending point (P2) of the strips (21) are spaced apart from each other in the tire circumference. The angle β formed by the starting point (P1) and the ending point (P2) of the strips (21) around the tire central axis (O) is greater than the angle α formed by the two endpoints (X1, X2) of the contact area around the tire central axis in the tire circumference.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire tread and a method for manufacturing the same, and more specifically, to a pneumatic tire capable of improving ride comfort and a method for manufacturing the same. 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, according to the inventors' understanding, in a sealant layer with a structure in which the sealant strip is arranged in a spiral along the tire circumference, if the start and end points of the strip are both located within the contact area, this can become a major cause of deterioration in ride comfort.

[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 that improves ride comfort when a sealant layer is provided on the inner surface of the tire at the tread area, and a method for manufacturing the same.

[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 an annular 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] A sealant layer is formed on the inner surface of the tire at the tread area. The sealant layer has a structure in which sealant strips are arranged in a spiral along the tire circumference. The start and end points of the strips are spaced apart from each other in the tire circumference. When the pneumatic tire is assembled on a regular rim and filled with a regular internal pressure, the angle β formed by the start and end points of the strips around the tire's central axis is greater than the angle α formed by the two ends of the tire's circumference around the tire's central axis when the pneumatic tire is placed vertically on a plane and a regular load is applied, as measured when the tire is assembled on a regular rim, filled with a regular internal pressure, and the tire is in contact with the ground.

[0016] The method for manufacturing a pneumatic tire according to the present invention for achieving the above-mentioned objectives is characterized in that, after manufacturing a pneumatic tire having a tread portion that extends in an annular 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 these sidewall portions,

[0017] A sealant layer is formed by applying a sealant strip in a spiral pattern along the tire circumference on the inner surface of the tire at the tread area, such that the start and end points of the strip are spaced apart in the tire circumference. The angle β between the start and end points of the strip around the tire's central axis is greater than the angle α between the two ends of the tire's circumference around the tire's central axis when the pneumatic tire is assembled on a rim and inflated to a standard internal pressure, and is placed vertically on a plane with a standard load applied.

[0018] Invention Effects

[0019] In this invention, in an inflatable tire with a sealant layer having a sealant strip arranged spirally along the tire circumference on the inner surface of the tire at the tread area, the start and end points of the sealant strip are spaced apart from each other in the tire circumference. The angle β of the narrow angle formed by the start and end points of the strip around the tire's central axis is set to be larger than the angle α of the narrow angle formed by the two ends of the tire's circumference in the contact area around the tire's central axis. As a result, the start and end points of the strip will not exist simultaneously in the contact area, thus improving ride comfort.

[0020] In this invention, it is preferable that the angle β is in the range of 60° to 180°. By setting the angle β within the above range, riding comfort can be effectively improved.

[0021] In this invention, it is preferable that, when a belt layer comprising belt cords inclined relative to the tire circumference is embedded in the tread portion, the width of the sealant layer is at least 90% of the width of the outermost belt layer in the tire's radial direction. By increasing the width of the sealant layer in this way and positioning the start and end points of the sealant strip further outward in the tire width direction, ride comfort can be effectively improved. Furthermore, by making the sealant layer sufficiently wide, good sealing performance can be ensured.

[0022] In this invention, it is preferable that the storage modulus G' of the sealant at 100°C is 20 kPa or less. Because the storage modulus G' of the sealant at 100°C is small, vibration of the sealant layer is suppressed, thus improving ride comfort.

[0023] In this invention, it is preferable that the loss modulus G” of the sealant at 100°C is 5 kPa or less. Since the loss modulus G” of the sealant at 100°C is small, the heating of the sealant layer is suppressed, thus reducing the impact on durability.

[0024] In this invention, it is preferred that the thickness of the sealant layer be in the range of 2.0 mm to 5.0 mm. This ensures puncture seal performance.

[0025] In this invention, it is preferable that the sealant is composed of an organosilicon-based composition. When the sealant is composed of a rubber composition primarily based on butyl rubber, the sealant cools before the surrounding portions of the sealant strip fuse together, resulting in poor integration between the surrounding portions of the sealant strip. Consequently, the sealant layer provides insufficient sealing. Furthermore, if the surrounding portions of the sealant strip lack sufficient integration, the sealant layer tends to flow towards the center of the tread due to centrifugal force generated during tire rotation, which is also a major cause of reduced sealing performance. In contrast, when the sealant is composed of an organosilicon-based composition, the surrounding portions of the sealant strip fuse easily during the curing reaction process, resulting in good integration between the surrounding portions of the sealant strip, thus improving the sealing performance achieved by the sealant layer. Additionally, because the surrounding portions of the sealant strip have good integration, the sealant layer 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. Furthermore, sealants composed of organosilicon-based compositions can be applied at low temperatures. For example, the temperature of a sealant applied to the inner surface of a tire can be below 70°C. Therefore, they also have the advantage of reducing the impact of heat on the tire and preventing the deterioration of tire performance.

[0026] 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.

[0027] In this invention, angle α is the angle measured when a pneumatic tire, assembled on a standard rim and inflated to the standard internal pressure, is placed vertically on a plane and subjected to a standard load. The angle α is the angle formed by the two endpoints of the tire's circumferential direction around the tire's central axis, representing the narrow angle. Angle β is the angle formed by the start and end points of the strip around the tire's central axis, representing the narrow angle, representing the narrow angle between the start and end points of the strip, also inflated on a standard rim and inflated to the standard internal pressure. "Standard rim" refers to a rim defined per tire within a standard system that includes the standard on which the tire is based; for example, if it is JATMA, then it is... "(Standard Rim)" refers to the tire pressure specified by each standard within a standard system that includes the standard on which the tire is based. If it's JATMA, it's "(Standard Rim)". "(Maximum tire pressure)" refers to the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if it is TRA, and "INFLATION PRESSURE" if it is ETRTO. "Regular load" refers to the load specified for each tire within the standard system that includes the standard on which the tire is based. If it is JATMA, it is... (Maximum load capacity) If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES (Tire load limits under various cold inflation pressures)"; if it is ETRTO, it is "LOAD CAPACITY (Load Capacity)".

[0028] In this invention, the storage modulus G' and loss modulus G” of the sealant were measured according to JIS-K6394 using a viscoelastic spectrometer (manufactured by Toyo Seiki Co., Ltd.) under the conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 100°C. Attached Figure Description

[0029] Figure 1 This is a meridional sectional view showing an inflatable tire constructed according to an embodiment of the present invention.

[0030] Figure 2 It means Figure 1 A cross-sectional view of the main parts of an inflatable tire.

[0031] Figure 3 It means Figure 1 A cross-sectional view of the manufacturing method of a pneumatic tire.

[0032] Figure 4 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.

[0033] Figure 5 (a) and (b) respectively represent Figure 1 pneumatic tires Figure 5 (a) is a side view under load conditions. Figure 5 (b) is a side view under no-load conditions.

[0034] Figure 6 This is a meridional sectional view showing an inflatable tire constructed according to other embodiments of the present invention. Detailed Implementation

[0035] The structure of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 as well as Figure 2 This is a diagram showing an inflatable tire constructed according to an embodiment of the present invention.

[0036] 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.

[0037] 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.

[0038] 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 radially innermost on the tire and a second belt layer 7B located outer 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, for example, set in the range of 10° to 40°. Steel cords are preferably used as the belt cords of the belt layers 7.

[0039] 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.

[0040] 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.

[0041] In the aforementioned pneumatic tire, a sealant layer 20 is formed continuously in the tire circumferential direction on the inner surface 10 of the tread portion 1. Preferably, the center position of the sealant layer 20 in the tire width direction coincides with the tire equator CL, but its center position can also be offset from the tire equator CL to either side in the tire width direction. The distance between the center position of the sealant layer 20 in the tire width direction and the tire equator CL 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. The sealant layer 20 has a structure in which the sealant strips 21 are arranged in a spiral shape along the tire circumferential direction (see reference). Figure 4 The sealant of the sealant layer 20 may be composed of a rubber composition based on butyl rubber, but is preferably composed of an organosilicon composition. The organosilicon composition comprises a synthetic polymer compound having a main skeleton realized by siloxane bonds.

[0042] 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 applying a sealant, for example, a silicone-based composition, to the inner surface 10 of the tire at the tread portion 1.

[0043] Figure 3 express Figure 1 The specific manufacturing method of pneumatic tires, Figure 4 This refers to the sealant layer formed on the inner surface of the tire at the tread area. Figure 3 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 4 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.

[0044] When a sealant strip 21 is applied in a spiral pattern along the tire circumference to form a sealant layer 20 on the inner surface 10 of the tire at the tread 1, such as Figure 4As shown, the starting point P1 and ending point P2 of the strip 21 are spaced apart on the tire circumferential direction Tc, and the angle β formed by the starting point P1 and ending point P2 of the strip 21 around the tire central axis O is larger than the angle α formed by the two endpoints X1 and X2 of the tire's contact area around the tire central axis O. Figure 5 As shown in (a), angle α is the angle formed by the two endpoints X1 and X2 of the tire's circumferential direction around the tire's central axis O when the pneumatic tire is placed vertically on a plane with a normal internal pressure, assembled on a normal rim, and subjected to a normal load. Figure 5 As shown in (b), angle β is the angle formed by the start point P1 and end point P2 of strip 21 around the tire's central axis O when the pneumatic tire is assembled on a regular rim and filled with regular internal pressure.

[0045] In the aforementioned pneumatic tire, in a pneumatic tire where the inner surface 10 of the tire at the tread 1 has a sealant layer 20 with a sealant strip 21 arranged in a spiral along the tire circumference, the starting point P1 and the ending point P2 of the sealant strip 21 are spaced apart from each other in the tire circumference. The angle β of the narrow angle formed by the starting point P1 and the ending point P2 of the strip 21 around the tire central axis O is set to be larger than the angle α of the narrow angle formed by the two endpoints X1 and X2 of the tire circumference in the contact area around the tire central axis O. As a result, the starting point P1 and the ending point P2 of the strip 21 will not exist in the contact area at the same time, thus improving ride comfort.

[0046] In the aforementioned pneumatic tires, the angle β is preferably in the range of 60° to 180°, and more preferably in the range of 90° to 180°. By setting the angle β within this range, ride comfort can be effectively improved. If the angle β is too small, the improvement in ride comfort is reduced. On the other hand, the angle α is typically in the range of 20° to 50°. Furthermore, it is preferable that the difference between angle β and angle α satisfies the relationship β - α ≥ 60°.

[0047] In the aforementioned pneumatic tire, if a multi-layered belt layer 7, comprising belt cords inclined relative to the tire circumference and arranged in a manner where the belt cords intersect each other, is embedded in the tread portion 1, and these belt layers 7 include a first belt layer 7A located at the innermost radial side of the tire and a second belt layer 7B located at the outermost radial side of the tire, then, Figure 1As shown, the width Ws of the sealant layer 20 is preferably at least 90% of the width Wb of the outermost belt layer 7B in the tire's radial direction. In particular, the end of the sealant layer 20 is preferably positioned further outward in the tire width direction than the end of the innermost belt layer 7A in the tire's radial direction. By making the width Ws of the sealant layer 20 sufficiently large relative to the width Wb of the belt layer 7B, and by positioning the start point P1 and end point P2 of the sealant strip 21 further outward in the tire width direction, ride comfort can be effectively improved. Furthermore, by sufficiently increasing the width Ws of the sealant layer 20, good sealing performance can be ensured. Here, if the width Ws of the sealant layer 20 is less than 90% of the width Wb of the belt layer 7B, the improvement in ride comfort is reduced, and puncture resistance is also reduced.

[0048] In the aforementioned pneumatic tire, the sealant is preferably composed of an organosilicon-based composition. By forming a sealant layer 20 on the inner surface 10 of the tire at the tread portion 1, the sealant layer 20 has a structure in which sealant strips 21 are arranged in a spiral along the tire circumference. Since the sealant is composed of an organosilicon-based composition, during the curing reaction process of the organosilicon 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, thus improving 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In the aforementioned pneumatic tire, the storage modulus G' of the sealant at 100°C is preferably below 20 kPa. Because the storage modulus G' of the sealant at 100°C is small, vibration of the sealant layer 20 is suppressed, thus improving ride comfort. If the storage modulus G' of the sealant at 100°C is greater than 20 kPa, the improvement in ride comfort is reduced. Particularly preferred is that the storage modulus G' of the sealant at 100°C is in the range of 5 kPa to 15 kPa.

[0053] In the aforementioned pneumatic tire, the loss modulus G” of the sealant at 100°C is preferably below 5 kPa. Because the loss modulus G” of the sealant at 100°C is small, the heating of the sealant layer 20 is suppressed, thus reducing the impact on durability. If the loss modulus G” of the sealant at 100°C is greater than 5 kPa, the improvement in durability is reduced. Particularly preferred is that the loss modulus G” of the sealant at 100°C is in the range of 1 kPa to 3 kPa.

[0054] In the aforementioned pneumatic tires, such as Figure 2 As 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 2 As shown, at all locations on the innermost radial side of the tire, the distance (minimum distance) L from the belt layer 7A to the sealant layer 20 should preferably be less than 10 mm. This allows the sealant to flow easily into the 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 belt layer 7A to the sealant layer 20 is greater than 10 mm, the puncture seal at those portions may be insufficient.

[0056] In the aforementioned pneumatic tire, the ratio of the thickness S of the sealant layer 20 to the distance L from the innermost radially innermost belt layer 7A to the sealant layer 20 should preferably be 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.

[0057] Figure 6 This diagram illustrates a pneumatic tire constructed according to other embodiments of the present invention. Figure 6In 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 particular, when the sealant of the sealant layer 20 is composed of an organosilicon-based composition, 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.

[0058] Example

[0059] Tires were manufactured as follows: Comparative Examples 1-2 and Examples 1-8. In an inflatable tire with a tire size of 255 / 45R19 and having a tread portion, a pair of sidewall portions and a pair of bead portions, a sealant layer with a sealant tape arranged in a spiral along the tire circumference was formed on the inner surface of the tire at the tread portion. The constituent material of the sealant layer, the angle α of the narrow angle formed by the two ends of the tire circumference of the contact area around the tire central axis, the angle β of the narrow angle formed by the start and end points of the tape around the tire central axis, the ratio of the width of the sealant layer to the width of the belt layer (Ws / Wb×100%), the storage modulus G' of the sealant at 100°C, the loss modulus G” of the sealant at 100°C, and the thickness S of the sealant layer were varied as shown in Table 1.

[0060] For these test tires, ride comfort and puncture seal were evaluated using the following test methods, and the results are shown in Table 1.

[0061] Ride comfort:

[0062] Each test tire was assembled onto a 19×8.5J rim size wheel and mounted on a 2400cc test vehicle (SUV). The tire pressure was set to 210 kPa, and the load was set to 100% of the maximum load capacity. A driving test based on the test driver was conducted, and sensory evaluation of ride comfort was performed. The evaluation results are expressed as an index with Comparative Example 1 set to 100. A higher index value indicates better ride comfort.

[0063] Puncture seal:

[0064] 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%."

[0065] [Table 1]

[0066]

[0067] As shown in Table 1, the tires of Examples 1 to 8 have good puncture resistance and, in addition, excellent ride comfort compared to Comparative Examples 1 and 2.

[0068] Explanation of reference numerals in the attached figures

[0069] 1. Fetal face

[0070] 2. Side of the tire

[0071] 3. Bead area

[0072] 4. Fetal body layers

[0073] 5. Bead core

[0074] 6. Bead filling

[0075] 7. Belt layer

[0076] 8. Belt Covering Layer

[0077] 10. Inner surface of the tire

[0078] 20. Sealant layer

[0079] 21. Sealant strips

[0080] 40 sound absorbing parts

[0081] P1 Starting point of strip

[0082] P2 End point of the strip

[0083] The two ends of the tire circumferential direction of the X1 and X2 ground contact areas

Claims

1. A pneumatic tire, the pneumatic tire comprising a tread portion extending in an annular 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 inward of the sidewall portions, characterized in that, A sealant layer is formed on the inner surface of the tire at the tread area. The sealant layer has a structure in which sealant strips are arranged in a spiral along the tire circumference. The start and end points of the strips are spaced apart from each other in the tire circumference. When the pneumatic tire is assembled on a regular rim and filled with a regular internal pressure, the angle β formed by the start and end points of the strips around the tire's central axis is greater than the angle α formed by the two ends of the tire's circumference around the tire's central axis when the pneumatic tire is placed vertically on a plane and a regular load is applied, as measured when the tire is assembled on a regular rim, filled with a regular internal pressure, and the tire is in contact with the ground.

2. The pneumatic tire according to claim 1, characterized in that, The angle β is in the range of 60° to 180°.

3. The pneumatic tire according to claim 1 or 2, characterized in that, A belt layer comprising belt cords inclined relative to the tire circumference is embedded in the tread portion, and the width of the sealant layer is more than 90% of the width of the belt layer located on the outermost radial side of the tire.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that, The energy storage modulus G' of the sealant at 100°C is below 20 kPa.

5. The pneumatic tire according to any one of claims 1 to 4, characterized in that, The loss modulus G” of the sealant at 100°C is below 5 kPa.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that, The thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that, The sealant is composed of an organosilicon-based composition.

8. The pneumatic tire according to claim 7, characterized in that, The organosilicon composition is a two-component cured organosilicon.

9. A method for manufacturing a pneumatic tire, characterized in that, After manufacturing an inflatable tire having a tread portion that extends 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 these sidewall portions, A sealant layer is formed by applying a sealant strip in a spiral pattern along the tire circumference on the inner surface of the tire at the tread area, such that the start and end points of the strip are spaced apart in the tire circumference. The angle β between the start and end points of the strip around the tire's central axis is greater than the angle α between the two ends of the tire's circumference around the tire's central axis when the pneumatic tire is assembled on a rim and inflated to a standard internal pressure, and is placed vertically on a plane with a standard load applied.

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