Tire and method for manufacturing tire

Abstract

To make reduction of noise and puncture sealing performance compatible and to secure high speed durability.SOLUTION: The pneumatic tire includes a tread part 2 extending in a tire circumferential direction and forming an annular shape, a sealant layer 50 arranged on a tire inner surface 18 in the tread part 2, and a plurality of chip-like sound absorbing materials 60 arranged on a tire inner cavity side in the sealant layer 50 and partially embedded in the sealant layer 50. As a result, the sealant layer 50 ensures the puncture sealing property, and the plurality of chipped sound absorbing members 60 suppress an increase in the volume of the member disposed on the tire cavity side to suppress heat generation, thereby ensuring high-speed durability and reducing noise.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tire and a method for manufacturing a tire. [Background technology]

[0002] One of the causes of tire noise is cavity resonance, which is caused by the vibration of the air filled in the tire cavity. This cavity resonance occurs when the tire tread, which comes into contact with the road surface while the vehicle is running, vibrates due to unevenness in the road surface, and this vibration vibrates the air inside the tire cavity. Within this cavity resonance, sounds in a specific frequency range are perceived as noise, so reducing the sound pressure level (noise level) in that frequency range is important in reducing cavity resonance.

[0003] One method for reducing noise caused by cavity resonance is to directly adhere a sound-absorbing material made of a porous material such as sponge to the inner surface of the tire. For example, Patent Document 1 describes a pneumatic tire in which a strip of sound-absorbing material is adhered to the inner surface of the tire along the circumferential direction of the tire, thereby reducing noise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 076380 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, pneumatic tires have been proposed that are provided with a sealant layer on the inner surface of the tire, allowing the tire to continue running even if a foreign object such as a nail penetrates the tread. That is, in such pneumatic tires with a sealant layer on the inner surface, when a foreign object such as a nail penetrates the tread, the sealant flows into the through hole where the foreign object has penetrated, thereby suppressing a decrease in air pressure and allowing the tire to continue running.

[0006] However, if a sound-absorbing material is placed on the inner surface of the tire to reduce cavity resonance, it may be difficult to provide a sealant layer, which may make it difficult to suppress a decrease in air pressure when a foreign object penetrates the tread. Alternatively, if a sealant layer is placed on the inner surface of the tire to suppress a decrease in air pressure when a foreign object penetrates the tread, it may be difficult to provide a sound-absorbing material, which may make it difficult to reduce noise with the sound-absorbing material.

[0007] Furthermore, when a strip-shaped sound-absorbing material is placed on the inner surface of the tire, the volume of the components placed on the tire cavity side increases, making the components, including the sound-absorbing material, placed on the tire cavity side more likely to generate heat when the vehicle is traveling at high speeds. In this case, the tire's durability is likely to decrease due to the heat generated, which could lead to a decrease in high-speed durability. For these reasons, it has been very difficult to achieve both noise reduction by the sound-absorbing material and puncture sealing properties by the sealant layer while also ensuring high-speed durability.

[0008] The present invention has been made in consideration of the above, and aims to provide a tire and a method for manufacturing the tire that can achieve both noise reduction and puncture sealing properties while ensuring high-speed durability. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the tire of the present invention is characterized by comprising a tread portion extending circumferentially in a ring shape in the tire circumferential direction, a sealant layer disposed on the tire inner surface in the tread portion, and a plurality of chip-shaped sound-absorbing materials disposed on the tire cavity side of the sealant layer, each of which has a portion embedded in the sealant layer.

[0010] In the tire, it is preferable that the chip-shaped sound absorbing material has an average particle size in the range of 1 mm to 10 mm.

[0011] In the tire, the sealant layer preferably has an average thickness in the range of 2 mm to 5 mm.

[0012] In the tire, it is preferable that the amount of the chip-shaped sound-absorbing material embedded in the sealant layer is within a range of 30% to 50% of the particle size of the chip-shaped sound-absorbing material.

[0013] In the tire, the chip-shaped sound-absorbing material preferably has a polyhedral shape.

[0014] In the tire, the chip-shaped sound absorbing material is preferably a porous material.

[0015] In the tire, the chip-shaped sound absorbing material is preferably a porous body made of soft polyurethane foam.

[0016] In the tire, the chip-shaped sound-absorbing material preferably has a packing rate of 50% or more per unit projected area on the sealant layer.

[0017] In the above tire, it is preferable that a belt layer is arranged in the tread portion, and that an outer end portion of the sealant layer in the tire width direction is located at a position that is within a range of 0% to 10% of the width of the belt layer in the tire width direction, from a point of intersection between the tire inner surface and a perpendicular line drawn from the end portion of the belt layer in the tire width direction toward the tire inner surface.

[0018] In the tire, it is preferable that a belt layer is disposed in the tread portion, and that an outer end portion of the sealant layer in the tire width direction is located at a position that is within a range of 0 mm to 10 mm outward in the tire width direction from an intersection of a perpendicular line drawn from the end portion of the belt layer in the tire width direction toward the tire inner surface and the tire inner surface.

[0019] In the tire, the sealant layer preferably has a glass transition temperature in the range of -120°C or higher and -40°C or lower.

[0020] In addition, in the above tire, it is preferable that the glass transition temperature of the sealant layer is lower than or equal to the glass transition temperature of the chip-shaped sound-absorbing material, and that the glass transition temperature of the chip-shaped sound-absorbing material is in the range of -60°C or higher and -40°C or lower.

[0021] In the tire, the sealant layer preferably contains a silyl group.

[0022] In the tire, the silicone composition constituting the sealant layer is preferably a two-component curing silicone.

[0023] In addition, in order to solve the above-mentioned problems and achieve the object, the tire manufacturing method of the present invention is characterized by including the steps of forming a sealant layer by applying sealant from a sealant nozzle to the inner surface of the tire in the tread portion of the tire, spraying chip-shaped sound-absorbing material from a sound-absorbing material nozzle onto the sealant layer, and rolling the roller while applying pressure to the sprayed chip-shaped sound-absorbing material to adhere the chip-shaped sound-absorbing material to the sealant layer.

[0024] In the tire manufacturing method, the sealant is preferably applied to the inner surface of the tire at a temperature of 70° C. or lower. [Effects of the Invention]

[0025] The tire and the tire manufacturing method according to the present invention have the effect of achieving both noise reduction and puncture sealing properties, and also ensuring high-speed durability. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic tire according to an embodiment. [Figure 2] FIG. 2 is a detailed view of part A in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of the shape of a chip-shaped sound absorbing material. [Figure 4] FIG. 4 is a schematic diagram of the sealant layer and the chip-shaped sound absorbing material as viewed in the direction of the arrow BB in FIG. [Figure 5] FIG. 5 is an explanatory diagram of a process for forming a sealant layer on the inner surface of a pneumatic tire. [Figure 6] FIG. 6 is a view taken along the arrow CC in FIG. 5, and is a plan view of a sealant layer formed on the inner surface of the tire. [Figure 7] FIG. 7 is an explanatory diagram of the step of scattering chip-shaped sound absorbing material. [Figure 8] FIG. 8 is an explanatory diagram of the process of adhering the chip-shaped sound absorbing material to the sealant layer. [Figure 9A] FIG. 9A is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 9B] FIG. 9B is a chart showing the results of a performance evaluation test of a pneumatic tire. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of a pneumatic tire and a method for manufacturing a pneumatic tire according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0028] [Embodiment] In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis (not shown), which is the rotational axis of the pneumatic tire 1. The tire radially inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radially outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. The tire width direction refers to the direction parallel to the tire rotational axis. The tire width inner side refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is perpendicular to the tire rotational axis and passes through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline, which is the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between the outermost portions in the tire width direction, i.e., the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line refers to a line that is on the tire equatorial plane CL and that runs along the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridian section refers to a cross section of the tire cut by a plane that includes the tire rotation axis.

[0029] FIG. 1 is a tire meridian cross-section showing a main portion of a pneumatic tire 1 according to this embodiment. When viewed in a tire meridian cross-section, the pneumatic tire 1 according to this embodiment has a tread portion 2 extending in the tire circumferential direction and forming an annular shape, disposed at the outermost portion in the tire radial direction. The tread portion 2 has a tread rubber 4 made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is traveling, is formed as a tread contact surface 3, and the tread contact surface 3 constitutes part of the contour of the pneumatic tire 1. The tread portion 2 has a plurality of circumferential grooves 30 formed in the tread contact surface 3 and extending in the tire circumferential direction. In this embodiment, four circumferential grooves 30 are arranged side by side in the tire width direction. The surface of the tread portion 2 is partitioned by the plurality of circumferential grooves 30 into a plurality of land portions 20 arranged side by side in the tire width direction.

[0030] The circumferential grooves 30 referred to here are grooves that are required to display a wear indicator as defined by JATMA. The circumferential grooves 30 may extend linearly along the tire circumferential direction, or may be formed in a zigzag shape by repeatedly bending or curving in the tire width direction while extending in the tire circumferential direction. The number of circumferential grooves 30 may be any number other than four.

[0031] In addition to the circumferential grooves 30 extending in the tire circumferential direction, lug grooves (not shown) extending in the tire width direction are provided in the tread contact surface 3. The tread contact surface 3 may also be provided with circumferential narrow grooves (not shown) extending in the tire circumferential direction with a groove width narrower than the circumferential grooves 30, sipes (not shown) formed in the tread contact surface 3 in the form of cuts, and the like.

[0032] Shoulder portions 5 are located at both outer ends of the tread portion 2 in the tire width direction, and sidewall portions 8 are arranged on the tire radially inward side of the shoulder portions 5. That is, the sidewall portions 8 are arranged on both sides of the tread portion 2 in the tire width direction. In other words, the sidewall portions 8 are arranged in two locations on both sides of the pneumatic tire 1 in the tire width direction, and form the outermost exposed portions of the pneumatic tire 1 in the tire width direction.

[0033] A bead portion 40 is located on the tire radially inner side of each sidewall portion 8 located on both sides in the tire width direction. Similar to the sidewall portions 8, the bead portions 40 are located at two positions on both sides of the tire equatorial plane CL; that is, a pair of bead portions 40 are located on both sides of the tire equatorial plane CL in the tire width direction. A bead core 41 is located in each bead portion 40, and a bead filler 45 is located on the tire radially outer side of the bead core 41. The bead core 41 is an annular member formed by bundling bead wires (not shown), which are steel wires, and the bead filler 45 is a rubber member located on the tire radially outer side of the bead core 41.

[0034] A belt layer 14 is also disposed in the tread portion 2. The belt layer 14 has a multi-layer structure in which a plurality of belts 141, 142 and a belt cover 143 are laminated. In this embodiment, two layers of belts 141, 142 are laminated. The belts 141, 142 constituting the belt layer 14 are formed by coating a plurality of belt cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the coated belt cords. The belt angle, defined as the inclination angle of the belt cords with respect to the tire circumferential direction, is within a predetermined range (for example, 20° to 55°). The two-layer belts 141, 142 have different belt angles. Therefore, the belt layer 14 has a so-called cross-ply structure in which the two-layer belts 141, 142 are laminated with the inclination directions of the belt cords crossing each other. In other words, the two-layer belts 141, 142 are provided as so-called cross belts in which the belt cords of the respective belts 141, 142 are arranged in a direction in which they cross each other.

[0035] The belt cover 143 is formed by covering a plurality of belt cover cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the covered cords, and the belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, is within a predetermined range (for example, 0° to 10°). The belt cover 143 is, for example, a strip material formed by covering one or more belt cover cords with coating rubber, and is formed by winding this strip material spirally around the tire rotation axis from the outer side in the tire radial direction of the two-layered belts 141 and 142.

[0036] A carcass layer 10 containing radial ply cords is provided continuously on the tire radially inward side of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 8. For this reason, the pneumatic tire 1 according to this embodiment is configured as a so-called radial tire. The carcass layer 10 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of a plurality of carcass plies stacked together, and is toroidally spanned between a pair of bead portions 40 arranged on both sides in the tire width direction to form the framework of the tire.

[0037] More specifically, the carcass layer 10 is disposed from one bead portion 40 to the other of a pair of bead portions 40 located on both sides in the tire width direction, and is wound back along the bead core 41 toward the outside in the tire width direction at the bead portion 40 so as to enclose the bead core 41 and the bead filler 45. Therefore, the carcass layer 10 has a carcass main body portion 10a disposed between the pair of bead portions 40, and a turn-up portion 10b formed continuously from the carcass main body portion 10a and folded back from the inside in the tire width direction of the bead core 41 toward the outside in the tire width direction.

[0038] The carcass main body 10a here is a portion formed across the inner sides of a pair of bead cores 41 in the carcass layer 10 in the tire width direction, and the turnup portion 10b is formed continuously from the carcass main body 10a on the inner side of the bead core 41 in the tire width direction, passing through the inner side of the bead core 41 in the tire radial direction and folded back to the outer side in the tire width direction. The bead filler 45 is arranged on the inner side in the tire width direction of the turnup portion 10b, which is the portion folded back to the outer side in the tire width direction of the bead core 41, and on the outer side in the tire radial direction of the bead core 41.

[0039] The bead filler 45 is made of a rubber material and is placed in a space formed radially outward of the bead core 41 by folding back the carcass layer 10 at the bead portions 40. The belt layer 14 is placed radially outward of the portion of the carcass layer 10 that is positioned in the tread portion 2 and that is stretched between the pair of bead portions 40. The carcass ply of the carcass layer 10 is formed by covering a plurality of carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with a coating rubber and rolling the covered cords. The carcass cords that make up the carcass ply are arranged in parallel at an angle relative to the tire circumferential direction, with the angle being aligned along the tire meridian direction.

[0040] In the bead portion 40, a rim cushion rubber 17 that forms the contact surface of the bead portion 40 with the rim flange is arranged on the tire radially inner side and tire widthwise outer side of the bead core 41 and the turned-up portion of the carcass layer 10. Furthermore, an inner liner 16 is formed along the carcass layer 10 on the inner side of the carcass layer 10 or on the inner side of the carcass layer 10 in the pneumatic tire 1. The inner liner 16 forms a tire inner surface 18, which is the inner surface of the pneumatic tire 1.

[0041] A sealant layer 50 is disposed on the tire inner surface 18 in the tread portion 2. The sealant layer 50 is formed by applying a sealant to the tire inner surface 18 in the tread portion 2, and is formed continuously in the tire circumferential direction.

[0042] In the sealant layer 50 provided on the tire inner surface 18 in the tread portion 2, a plurality of chip-shaped sound-absorbing materials 60 are arranged on the tire cavity side of the sealant layer 50. The chip-shaped sound-absorbing materials 60 are sound-absorbing materials that have sound-absorbing functions and are in the form of relatively small chips. A portion of each of the plurality of chip-shaped sound-absorbing materials 60 is embedded in the sealant layer 50. Therefore, the plurality of chip-shaped sound-absorbing materials 60 are adhered to the tire inner surface 18 by the sealant layer 50.

[0043] The chip-shaped sound absorbing material 60 referred to here refers to a "sound absorbing material (material used for the purpose of absorbing sound)" described in JIS A 6301 that has been made into chip form.

[0044] The sealant of the sealant layer 50 is preferably composed of a silicone-based composition. Silicone-based compositions include synthetic polymer compounds with a main skeleton formed by siloxane bonds. The use of such a sealant has low temperature dependency and can maintain its physical properties over a wide range of temperatures, from low to high, so it tends to be less likely to flow at high temperatures and less likely to crack at low temperatures. Furthermore, it is possible to achieve both puncture sealing properties and durability. Furthermore, the adhesion to the chip-shaped sound-absorbing material 60 also has low temperature dependency, allowing good adhesion to be maintained over a wide range of temperatures.

[0045] Fig. 2 is a detailed view of part A in Fig. 1. In the tire meridian cross section, the sealant layer 50 arranged on the tire inner surface 18 of the tread portion 2 is located such that an outer end 51 of the sealant layer 50 in the tire width direction is in a range of 0% to 10% of the width WB (see Fig. 1) of the belt layer 14 in the tire width direction in a direction along the periphery of the tire inner surface 18 toward the outside in the tire width direction from an intersection P between the tire inner surface 18 and a perpendicular line L drawn from an end 145 of the belt layer 14 in the tire width direction toward the tire inner surface 18. In this case, the width WB of the belt layer 14 is the maximum width of the belt layer 14 in the tire width direction.

[0046] It is preferable that the sealant layer 50 is positioned such that its outer end 51 in the tire width direction is within a range of 0 mm or more and 10 mm or less in a direction along the periphery of the tire inner surface 18 toward the outside in the tire width direction from an intersection P between the tire inner surface 18 and a perpendicular line L drawn from the end 145 of the belt layer 14 toward the tire inner surface 18.

[0047] The sealant layer 50 disposed on the tire inner surface 18 has an average thickness Ga of 2 mm or more and 5 mm or less. The average thickness Ga of the sealant layer 50 is the average thickness of the entire sealant layer 50.

[0048] The average thickness Ga of the sealant layer 50 is calculated, for example, by taking images of a meridian cross section of the tire at eight points around the circumference of the tire using a CT scan, measuring the thickness of the sealant layer 50 at five points in each of the images taken: the position of the tire equatorial plane CL, outer edge positions (on both sides) 10 mm inward in the tire width direction from the end 51 of the sealant layer 50, and intermediate positions (on both sides) between the position of the tire equatorial plane CL and the outer edge positions, and then averaging the measured values ​​at a total of 40 points to calculate the average thickness Ga of the sealant layer 50.

[0049] The multiple chip-like sound-absorbing materials 60 arranged on the tire cavity side of the sealant layer 50 are made of a porous material with many tiny holes formed therein. The chip-like sound-absorbing materials 60 are porous because they are made of soft polyurethane foam, for example; that is, the chip-like sound-absorbing materials 60 are porous because they are made of sponge.

[0050] When the chip-shaped sound-absorbing material 60 is made of soft polyurethane foam, it is preferable that the foaming ratio of the soft polyurethane foam that makes up the chip-shaped sound-absorbing material 60 is in the range of 20 times or more and 50 times or less.

[0051] The chip-shaped sound-absorbing material 60 formed as a porous body has a spherical or polyhedral shape, with a polyhedral shape being preferable. Fig. 3 is a schematic diagram showing an example of the shape of the chip-shaped sound-absorbing material 60. When the chip-shaped sound-absorbing material 60 is formed in a polyhedral shape, it may be, for example, a regular octahedron as shown in Fig. 3(a), a regular dodecahedron as shown in Fig. 3(b), or a regular tetrahedron as shown in Fig. 3(c).

[0052] The chip-shaped sound-absorbing material 60 formed in this manner in a polyhedral or spherical shape preferably has an average particle size in the range of 1 mm to 10 mm. In this case, the average particle size is the average size of the particle sizes D of all the chip-shaped sound-absorbing materials 60 arranged in the sealant layer 50. It is preferable that the maximum particle size D of the chip-shaped sound-absorbing material 60 is 5 mm or less.

[0053] The chip-shaped sound-absorbing material 60 is embedded in the sealant layer 50 so that the embedding amount E is within the range of 30% to 50% of the particle size D of the chip-shaped sound-absorbing material 60. Therefore, each of the multiple chip-shaped sound-absorbing materials 60 arranged in the sealant layer 50 is partially embedded in the sealant layer 50, while the other portions are exposed to the tire cavity side.

[0054] Fig. 4 is a schematic diagram of the sealant layer 50 and the chip-shaped sound-absorbing materials 60 as seen in the direction of the arrow BB in Fig. 2. The plurality of chip-shaped sound-absorbing materials 60, each partially embedded in the sealant layer 50 and arranged on the sealant layer 50, have a packing rate of 50% or more per unit projected area on the sealant layer 50. In this case, the packing rate is the ratio of the size of the projected area of ​​the plurality of chip-shaped sound-absorbing materials 60 included in an arbitrary range to the area of ​​the sealant layer 50 when the sealant layer 50 on which the plurality of chip-shaped sound-absorbing materials 60 are arranged is viewed in the thickness direction of the sealant layer 50.

[0055] The sealant layer 50 disposed on the tire inner surface 18 together with the chip-shaped sound-absorbing material 60 preferably has a glass transition temperature in the range of −120° C. or higher and −40° C. or lower. Furthermore, the sealant layer 50 and the chip-shaped sound-absorbing material 60 preferably have a glass transition temperature in the range of −60° C. or higher and −40° C. or lower.

[0056] Next, a method for manufacturing a pneumatic tire 1 according to an embodiment will be described. FIG. 5 is an explanatory diagram illustrating a step of forming a sealant layer 50 on the tire inner surface 18 of the pneumatic tire 1. FIG. 6 is a view taken along the arrow CC in FIG. 5, and is a plan view of the sealant layer 50 formed on the tire inner surface 18. When forming the sealant layer 50 on the tire inner surface 18 in the tread portion 2 of the pneumatic tire 1, a sealant is applied to the tire inner surface 18 from a sealant nozzle 74. The sealant nozzle 74 is capable of discharging the sealant extruded from a sealant extrusion device 71 as a strip-shaped strip 52. The sealant extrusion device 71 mixes the sealants supplied from pumps 72 and 73, and extrudes the mixed sealant toward the sealant nozzle 74.

[0057] In the process of forming the sealant layer 50 on the tire inner surface 18, the sealant nozzle 74 is arranged in the tire cavity together with the sealant extrusion device 71 so as to be movable in the tire width direction and the tire radial direction. In the process of forming the sealant layer 50 on the tire inner surface 18, the sealant nozzle 74 is moved in the tire width direction while the pneumatic tire 1 is rotated and the sealant nozzle 74 is moved in the tire width direction, with the sealant nozzle 74 being brought close to the tire inner surface 18 and the sealant is discharged as a strip 52 from the sealant nozzle 74. This allows the sealant strip 52 to be arranged on the tire inner surface 18 in a spiral shape that is inclined toward the tire width direction with respect to the tire circumferential direction (see FIG. 6 ).

[0058] When the sealant strip 52 is arranged in a spiral shape, the moving speed of the sealant nozzle 74 in the tire width direction and the rotational speed of the pneumatic tire 1 are adjusted to bring the wound portions of the strip 52 into close contact with each other. This allows the spirally arranged sealant strip 52 to be integrated, and the sealant strip 52 can form the sealant layer 50 on the tire inner surface 18.

[0059] The sealant of the sealant layer 50 is composed of, for example, a silicone-based composition. When a silicone-based composition is used for the sealant of the sealant layer 50, the silicone-based composition has good fluidity even at low temperatures, and therefore, when the sealant is applied to the tire inner surface 18, the sealant is applied to the tire inner surface 18 with its temperature set to 70°C or less.

[0060] The temperature of the sealant when applied to the tire inner surface 18 is preferably in the range of 5°C or higher and 40°C or lower, more preferably in the range of 10°C or higher and 35°C or lower, and most preferably in the range of 15°C or higher and 30°C or lower.

[0061] As the silicone-based composition constituting the sealant of the sealant layer 50, one-component curing silicone or two-component curing silicone can be used, but it is particularly preferable to use two-component curing silicone. An example of one-component curing silicone is moisture-curing silicone. Two-component curing silicone is composed of a first component and a second component, and mixing these first and second components initiates a curing reaction, ensuring the stability of the sealant layer 50 after curing. In this embodiment, the first component and second component of the two-component curing silicone are supplied from pumps 72 and 73, respectively. Two-component curing silicone has low viscosity immediately after mixing the two components, allowing it to be applied even at low temperatures.

[0062] Two-component curing silicones are composed of, for example, a condensation-curable silyl-terminated polymer, a silane crosslinker, a condensation catalyst, a filler, and the like. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers having silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylenes having silyl groups. Examples of silane crosslinkers include alkoxy-functional silanes, oximosilanes, acetoxysilanes, and enoxysilanes. Examples of fillers include iron oxide, titanium dioxide, carbon black, and talc. Examples of condensation catalysts include titanates and zirconates. These condensation-curable silyl-terminated polymers, silane crosslinkers, condensation catalysts, and fillers are stored in a first and second liquid form in a combination that does not promote a curing reaction, and are mixed when used.

[0063] After the sealant layer 50 has been formed on the tire inner surface 18, chip-like sound-absorbing material 60 is then sprayed onto the sealant layer 50. FIG. 7 is an explanatory diagram of the process of spraying chip-like sound-absorbing material 60. The chip-like sound-absorbing material 60 is sprayed onto the sealant layer 50 formed on the tire inner surface 18 by spraying the chip-like sound-absorbing material 60 onto the sealant layer 50 from a sound-absorbing material nozzle 83. The sound-absorbing material nozzle 83 is capable of spraying the chip-like sound-absorbing material 60 sent from a sound-absorbing material spraying device 81. The sound-absorbing material spraying device 81 uses air pressure to send the chip-like sound-absorbing material 60 supplied from a sound-absorbing material supply unit 82 toward the sound-absorbing material nozzle 83.

[0064] In the process of spraying chip-like sound-absorbing material 60 onto the sealant layer 50 on the tire inner surface 18, the sound-absorbing material nozzle 83 is placed in the tire cavity together with the sound-absorbing material spraying device 81 so that it can move in the tire width direction and the tire radial direction. In the process of spraying chip-like sound-absorbing material 60 onto the sealant layer 50, the sound-absorbing material nozzle 83 is moved in the tire width direction while the pneumatic tire 1 is rotated and the sound-absorbing material nozzle 83 is moved in the tire width direction while the sound-absorbing material nozzle 83 is brought close to the sealant layer 50 on the tire inner surface 18 and sprays multiple chip-like sound-absorbing material 60 from the sound-absorbing material nozzle 83. In this way, the chip-like sound-absorbing material 60 is sprayed evenly onto the sealant layer 50 on the tire inner surface 18.

[0065] Because the sealant layer 50 formed on the tire inner surface 18 is viscous and adhesive, the chip-like sound-absorbing material 60 scattered on the sealant layer 50 is adhered to the sealant layer 50 by the adhesiveness of the sealant layer 50. As a result, in the process of scattering the chip-like sound-absorbing material 60 on the sealant layer 50, multiple chip-like sound-absorbing materials 60 can be scattered evenly and adhered to the sealant layer 50 formed on the tire inner surface 18.

[0066] After the chip-like sound-absorbing material 60 has been scattered on the sealant layer 50, the chip-like sound-absorbing material 60 is then brought into close contact with the sealant layer 50. FIG. 8 is an explanatory diagram of the process of bringing the chip-like sound-absorbing material 60 into close contact with the sealant layer 50. The chip-like sound-absorbing material 60 is brought into close contact with the sealant layer 50 by rolling the roller 90 while applying pressure to the chip-like sound-absorbing material 60 scattered toward the sealant layer 50. The roller 90 is formed in a substantially cylindrical shape, and support members 91 are connected to both ends of the cylinder in the axial direction, and the roller 90 is rotatably supported by the support members 91.

[0067] In the process of adhering the chip-shaped sound-absorbing material 60 to the sealant layer 50, the roller 90 is placed in the tire cavity together with the support member 91 so that it can move in the tire width direction and the tire radial direction. The roller 90 is also placed in the tire cavity with its axial direction oriented approximately in the tire width direction. In the process of adhering the chip-shaped sound-absorbing material 60 to the sealant layer 50, the roller 90 is brought into contact with the chip-shaped sound-absorbing material 60 from the inside in the tire radial direction in the tire cavity, and pressure is applied to the chip-shaped sound-absorbing material 60 in the outward direction in the tire radial direction. In other words, the roller 90 applies pressure to the chip-shaped sound-absorbing material 60 on the sealant layer 50 toward the side where the sealant layer 50 is located.

[0068] In this manner, the pneumatic tire 1 is rotated while pressure is being applied to the chip-like sound-absorbing material 60 by the roller 90, and the roller 90 is moved in the tire width direction. This causes the chip-like sound-absorbing material 60 to be roll-pressed against the sealant layer 50 by the roller 90 so that the chip-like sound-absorbing material 60 on the sealant layer 50 is in even contact with the sealant layer 50.

[0069] More specifically, when pressure is applied from the roller 90 to the chip-shaped sound-absorbing material 60 toward the side where the sealant layer 50 is located, the sealant layer 50 is viscous, so the pressure from the roller 90 causes the chip-shaped sound-absorbing material 60 to push the sealant layer 50 aside and move outward in the radial direction of the tire. As a result, the chip-shaped sound-absorbing material 60 penetrates the sealant layer 50 and becomes partially embedded in the sealant layer 50. When the chip-shaped sound-absorbing material 60 is embedded in the sealant layer 50, the contact area between the chip-shaped sound-absorbing material 60 and the sealant layer 50 increases, so the chip-shaped sound-absorbing material 60, which is adhered to the sealant layer 50 due to the adhesiveness of the sealant layer 50, is more firmly adhered to the sealant layer 50.

[0070] In the process of adhering the chip-shaped sound-absorbing material 60 to the sealant layer 50, pressure is applied to the chip-shaped sound-absorbing material 60 with the roller 90 in this manner, causing part of the chip-shaped sound-absorbing material 60 to become embedded in the sealant layer 50, thereby firmly adhering the chip-shaped sound-absorbing material 60 to the sealant layer 50. In this way, the adhesiveness of the sealant layer 50 allows the multiple chip-shaped sound-absorbing materials 60 to be positioned on the tire inner surface 18.

[0071] When mounting the pneumatic tire 1 according to this embodiment on a vehicle, the pneumatic tire 1 is mounted on the rim wheel by fitting the bead portion 40 onto the rim wheel, and the tire is mounted on the vehicle in an inflated state with air filled inside. When a vehicle mounted with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the lower portion of the tread contact surface 3 comes into contact with the road surface. The vehicle runs by transmitting driving force and braking force to the road surface and generating turning force due to the frictional force between the tread contact surface 3 and the road surface.

[0072] For example, when a vehicle equipped with the pneumatic tire 1 travels on a dry road surface, the vehicle travels by transmitting driving force and braking force to the road surface and generating turning force mainly through the frictional force between the tread contact surface 3 and the road surface. When traveling on a wet road surface, water between the tread contact surface 3 and the road surface enters grooves such as the circumferential grooves 30 and lug grooves, and these grooves drain the water between the tread contact surface 3 and the road surface while traveling. This makes it easier for the tread contact surface 3 to contact the road surface, and the frictional force between the tread contact surface 3 and the road surface enables the vehicle to travel as desired.

[0073] When a vehicle is traveling, the tread contact surface 3 of the pneumatic tire 1 comes into contact with the road surface, but there may be foreign objects such as nails on the road surface on which the vehicle is traveling. For this reason, when the vehicle travels over a foreign object on the road surface, the tread portion 2 of the pneumatic tire 1 may run over the foreign object, causing the foreign object to pierce the tread portion 2. If a foreign object such as a nail pierces the tread portion 2 and penetrates the tread portion 2 in the thickness direction of the tread portion 2, the air filled in the pneumatic tire 1 may leak from the hole in the tread portion 2 where the foreign object pierced, causing a so-called puncture.

[0074] In contrast, in the pneumatic tire 1 according to this embodiment, the sealant layer 50 is disposed on the tire inner surface 18 in the tread portion 2, so that even if a foreign object such as a nail pierces the tread portion 2 and penetrates through the tread portion 2, the foreign object protruding onto the tire inner surface 18 can be covered by the sealant layer 50.

[0075] Furthermore, if a foreign object that has penetrated the tread portion 2 escapes from the tread portion 2, the sealant in the sealant layer 50 flows into the through hole in the tread portion 2 where the foreign object has penetrated, thereby sealing the through hole. As a result, even if a foreign object has penetrated the tread portion 2, the sealant layer 50 can prevent the outside of the pneumatic tire 1 from communicating with the tire cavity through a through hole formed by the foreign object. Therefore, even if a foreign object has penetrated the tread portion 2, it is possible to prevent the air filled in the pneumatic tire 1 from leaking through the through hole, and the sealant layer 50 can ensure puncture sealing properties against punctures, thereby maintaining a state in which the tire can be driven.

[0076] Furthermore, when the vehicle is traveling, the pneumatic tire 1 is subjected to a large load in the tire radial direction due to the weight of the vehicle body and loads associated with acceleration, deceleration, and cornering. This load is primarily borne by the air filled inside the pneumatic tire 1, but is also borne by the tread portion 2 and the sidewall portions 8 in addition to the air inside the pneumatic tire 1. That is, the sidewall portions 8 transmit the load between the tread portion 2 and the bead portions 40, into which the rim wheel is fitted, and the tread portion 2 transmits the load between the sidewall portions 8 and the road surface. For this reason, a large load is exerted on the sidewall portions 8 and the tread portion 2 when the vehicle is traveling, and the sidewall portions 8 and the tread portion 2 receive this load while deflecting mainly in the tire radial direction.

[0077] Furthermore, when the vehicle is running, the pneumatic tire 1 rotates, so the position of the tread contact surface 3 that comes into contact with the road surface continuously moves in the circumferential direction of the tire, and accordingly, the positions in the sidewall portion 8 and the tread portion 2 that are deflected by the load when the vehicle is running also move in the circumferential direction of the tire. Therefore, when the vehicle is running, the pneumatic tire 1 rotates while the sidewall portion 8 and the tread portion 2 repeatedly deflect sequentially at each position in the circumferential direction of the tire.

[0078] When the vehicle is running, the rotation of the pneumatic tire 1 causes the circumferential position of the flexed portion to move in the circumferential direction of the tire, causing vibrations in the air filled inside the pneumatic tire 1. When the air filled in the tire cavity vibrates, the air vibrations can generate cavity resonance noise, and cavity resonance noise in a specific frequency band is easily perceived as noise by vehicle occupants.

[0079] In contrast, in the pneumatic tire 1 according to this embodiment, a plurality of chip-shaped sound-absorbing materials 60, each partially embedded in the sealant layer 50, are arranged on the tire cavity side of the sealant layer 50 arranged on the tire inner surface 18. In other words, when a sealant layer 50 for ensuring puncture sealing is provided on the tire inner surface 18 of the pneumatic tire 1, it becomes difficult to arrange sound-absorbing material on the tire inner surface 18. However, in this embodiment, a plurality of chip-shaped sound-absorbing materials 60, which are relatively small chip-shaped sound-absorbing materials, are arranged in the sealant layer 50.

[0080] Therefore, while the sealant layer 50 ensures puncture sealing performance, the plurality of chip-shaped sound-absorbing materials 60 arranged in the sealant layer 50 can absorb cavity resonance generated in the tire cavity of the pneumatic tire 1 when the vehicle is running. Furthermore, because the chip-shaped sound-absorbing materials 60 are arranged in multiple small chip-shaped sound-absorbing materials, the overall surface area of ​​the sound-absorbing material relative to the overall volume of the sound-absorbing material can be increased. This allows the plurality of chip-shaped sound-absorbing materials 60 to efficiently absorb cavity resonance generated in the tire cavity. Therefore, the plurality of chip-shaped sound-absorbing materials 60 can reduce noise caused by cavity resonance generated in the tire cavity when the vehicle is running.

[0081] Furthermore, if, for example, a strip-shaped sound-absorbing material extending in the tire circumferential direction and having a width in the tire width direction approximately equal to the width of the tread portion 2 is disposed as the sound-absorbing material disposed on the tire inner surface 18, the volume of the components disposed on the tire cavity side increases. When the pneumatic tire 1 is driven at high speeds, the components constituting the pneumatic tire 1 generate heat due to elastic deformation. If the volume of the components disposed on the tire cavity side increases, the volume of the components that generate heat when the vehicle is driven at high speeds increases, making the tire more susceptible to heat generation. In this case, the durability of the pneumatic tire 1 is likely to decrease as a result of heat generation, i.e., there is a risk that high-speed durability may be easily reduced.

[0082] In contrast, in this embodiment, the sound-absorbing material placed on the tire inner surface 18 is chip-like sound-absorbing material 60, which is relatively small in size, so that when sound-absorbing material is placed on the tire inner surface 18, it is possible to suppress an increase in the volume of the components placed on the tire cavity side. This makes it possible to suppress the volume of the components that generate heat when the vehicle is traveling at high speeds, and to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds, thereby suppressing a decrease in high-speed durability due to heat generation. As a result, it is possible to achieve both noise reduction and puncture sealing performance, while ensuring high-speed durability.

[0083] Furthermore, because the chip-shaped sound-absorbing material 60 has an average particle size within the range of 1 mm to 10 mm, the chip-shaped sound-absorbing material 60 can absorb cavity resonance noise generated in the tire cavity while suppressing heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds. In other words, if the average particle size of the chip-shaped sound-absorbing material 60 is less than 1 mm, the average particle size of the chip-shaped sound-absorbing material 60 is too small, making it difficult to ensure the sound absorption performance of the chip-shaped sound-absorbing material 60 and potentially making it difficult for the chip-shaped sound-absorbing material 60 to absorb cavity resonance noise generated in the tire cavity. If the average particle size of the chip-shaped sound-absorbing material 60 is greater than 10 mm, the average particle size of the chip-shaped sound-absorbing material 60 is too large, making it difficult to suppress an increase in the volume of the component disposed on the tire cavity side and potentially making it difficult to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds.

[0084] In contrast, when the average particle size of the chip-shaped sound-absorbing material 60 is within the range of 1 mm or more and 10 mm or less, it is possible to ensure the sound-absorbing performance of the chip-shaped sound-absorbing material 60 while suppressing an increase in the volume of the component placed on the tire cavity side. This allows the chip-shaped sound-absorbing material 60 to absorb cavity resonance noise generated in the tire cavity while suppressing heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds. As a result, it is possible to more reliably reduce the noise of the pneumatic tire 1 when the vehicle is traveling and ensure high-speed durability.

[0085] Furthermore, because the sealant layer 50 has an average thickness Ga within the range of 2 mm to 5 mm, it is possible to suppress an increase in the volume of components disposed on the tire cavity side while suppressing air leakage when a foreign object penetrates the tread portion 2. In other words, if the average thickness Ga of the sealant layer 50 is less than 2 mm, the average thickness Ga of the sealant layer 50 is too thin, making it difficult for the sealant layer 50 to suppress air leakage when a foreign object such as a nail penetrates the tread portion 2, and there is a risk that it will be difficult to ensure puncture sealing performance. If the average thickness Ga of the sealant layer 50 is greater than 5 mm, the average thickness Ga of the sealant layer 50 is too thick, making it easy for the volume of components disposed on the tire cavity side to increase, and there is a risk that it will be difficult to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds.

[0086] In contrast, when the average thickness Ga of the sealant layer 50 is within the range of 2 mm or more and 5 mm or less, it is possible to ensure a thickness of the sealant layer 50 that can effectively prevent air leakage when a foreign object penetrates the tread portion 2, while suppressing an increase in the volume of components disposed on the tire cavity side that would result from an increase in the thickness of the sealant layer 50. This makes it possible to ensure puncture sealing performance while suppressing heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds. As a result, it is possible to more reliably ensure the puncture sealing performance of the pneumatic tire 1 and ensure high-speed durability.

[0087] Furthermore, because the embedding amount E of the chip-shaped sound-absorbing material 60 in the sealant layer 50 is within a range of 30% to 50% of the particle size D of the chip-shaped sound-absorbing material 60, it is possible to ensure the amount of exposed chip-shaped sound-absorbing material 60 from the sealant layer 50 while ensuring adhesion between the sealant layer 50 and the chip-shaped sound-absorbing material 60. In other words, if the embedding amount E of the chip-shaped sound-absorbing material 60 is less than 30% of the particle size D of the chip-shaped sound-absorbing material 60, the embedding amount E in the sealant layer 50 is too small, which may make it difficult to ensure adhesion between the sealant layer 50 and the chip-shaped sound-absorbing material 60. In this case, the chip-shaped sound-absorbing material 60 is less likely to fall off the sealant layer 50, which may reduce the number of chip-shaped sound-absorbing materials 60 arranged in the sealant layer 50, making it difficult to effectively ensure the sound absorption performance of the chip-shaped sound-absorbing material 60. Furthermore, if the embedded amount E of the chip-shaped sound-absorbing material 60 is greater than 50% of the particle size D of the chip-shaped sound-absorbing material 60, the embedded amount E in the sealant layer 50 will be too large, and there is a risk that too little of the chip-shaped sound-absorbing material 60 will be exposed from the sealant layer 50. In this case, the surface area of ​​the part of the chip-shaped sound-absorbing material 60 that absorbs cavity resonance noise generated in the tire cavity will be reduced, and there is a risk that it will be difficult to effectively ensure the sound-absorbing performance of the chip-shaped sound-absorbing material 60.

[0088] In contrast, when the embedded amount E of the chip-shaped sound-absorbing material 60 is within the range of 30% to 50% of the particle size D of the chip-shaped sound-absorbing material 60, it is possible to ensure the amount of exposed chip-shaped sound-absorbing material 60 from the sealant layer 50 while ensuring adhesion between the sealant layer 50 and the chip-shaped sound-absorbing material 60. This makes it possible to prevent the chip-shaped sound-absorbing material 60 from falling off the sealant layer 50, while allowing the chip-shaped sound-absorbing material 60 to absorb cavity resonance noise generated in the tire cavity. As a result, it is possible to more reliably reduce noise from the pneumatic tire 1 when the vehicle is running.

[0089] Furthermore, because the chip-shaped sound-absorbing material 60 has a polyhedral shape, the surface area relative to the volume of the chip-shaped sound-absorbing material 60 can be made larger than if the chip-shaped sound-absorbing material 60 were spherical. This increases the contact area of ​​the chip-shaped sound-absorbing material 60 with the sealant layer 50, ensuring adhesion between the two and also ensuring the area of ​​the portion of the chip-shaped sound-absorbing material 60 that absorbs cavity resonance generated in the tire cavity. This prevents the chip-shaped sound-absorbing material 60 from falling off the sealant layer 50, while allowing the chip-shaped sound-absorbing material 60 to effectively absorb cavity resonance generated in the tire cavity. As a result, noise from the pneumatic tire 1 when the vehicle is running can be more reliably reduced.

[0090] Furthermore, because the chip-shaped sound-absorbing material 60 is porous, it is possible to increase the number of holes that absorb sound in the chip-shaped sound-absorbing material 60. This allows the cavity resonance sound generated in the tire cavity of the pneumatic tire 1 to be absorbed by the many holes in the chip-shaped sound-absorbing material 60, and the cavity resonance sound can be effectively absorbed by the chip-shaped sound-absorbing material 60. As a result, it is possible to more reliably reduce the noise of the pneumatic tire 1 when the vehicle is running.

[0091] Furthermore, because the chip-shaped sound-absorbing material 60 is made of soft polyurethane foam, it is easy to obtain porous chip-shaped sound-absorbing material 60. As a result, it is possible to reduce noise from the pneumatic tire 1 when the vehicle is running while suppressing increases in manufacturing costs.

[0092] Furthermore, because the packing rate of the chip-shaped sound-absorbing material 60 per unit projected area on the sealant layer 50 is 50% or more, it is possible to suppress the reduction in sealant in the sealant layer 50 and ensure the thickness of the sealant layer 50. In other words, if the packing rate of the chip-shaped sound-absorbing material 60 per unit projected area on the sealant layer 50 is less than 50%, the packing rate of the chip-shaped sound-absorbing material 60 is too low, and there is a risk that the area of ​​the sealant layer 50 where the chip-shaped sound-absorbing material 60 is not disposed will become too large. In this case, during the manufacturing process of the pneumatic tire 1, when the roller 90 is used to bring the chip-shaped sound-absorbing material 60 into close contact with the sealant layer 50, more sealant comes into contact with the roller 90, and more sealant adheres to the roller 90, which may make it easier for the sealant in the sealant layer 50 to be reduced.

[0093] In contrast, when the filling rate of the chip-shaped sound-absorbing material 60 per unit projected area on the sealant layer 50 is 50% or more, it is possible to prevent the area of ​​the sealant layer 50 where the chip-shaped sound-absorbing material 60 is not disposed from becoming too large. As a result, when the roller 90 is used to bring the chip-shaped sound-absorbing material 60 into close contact with the sealant layer 50 during the manufacturing process of the pneumatic tire 1, it is possible to prevent the sealant from adhering to the roller 90, and it is possible to prevent the sealant from being reduced in the sealant layer 50, thereby ensuring the thickness of the sealant layer 50. As a result, it is possible to more reliably ensure puncture sealing performance.

[0094] Furthermore, the sealant layer 50 has an end 51 in the tire width direction that is located within a range of 0% to 10% of the width WB of the belt layer 14 in the tire width direction from the intersection P of the tire inner surface 18 and the perpendicular line L drawn from the end 145 of the belt layer 14 toward the tire inner surface 18, toward the outside in the tire width direction. This makes it possible to suppress an increase in the volume of the components arranged on the tire cavity side, while also preventing air leakage when a foreign object pierces the tread portion 2, by the sealant layer 50.

[0095] In other words, if the end 51 of the sealant layer 50 is located at a position that is less than 0% of the width WB of the belt layer 14 toward the outside in the tire width direction from the intersection P of the perpendicular line L and the tire inner surface 18, there is a risk that the width of the sealant layer 50 in the tire width direction will be too narrow. In this case, if a foreign object such as a nail penetrates into a position in the tread portion 2 near the shoulder portion 5 while the vehicle is running, the foreign object will penetrate into a position on the tire inner surface 18 that is further outward in the tire width direction than the portion where the sealant layer 50 is located, and there is a risk that it will become difficult for the sealant layer 50 to suppress air leakage from a through hole created by the foreign object.

[0096] Furthermore, if the end 51 of the sealant layer 50 is located at a position greater than 10% of the width WB of the belt layer 14 from the intersection P of the perpendicular line L and the tire inner surface 18 toward the outside in the tire width direction, the width of the sealant layer 50 in the tire width direction may become too wide. In this case, the volume of the sealant layer 50 tends to increase, which tends to increase the volume of the components disposed on the tire cavity side, making it difficult to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds.

[0097] In contrast, when the end 51 of the sealant layer 50 is positioned within a range of 0% to 10% of the width WB of the belt layer 14 from the intersection P of the perpendicular line L and the tire inner surface 18 toward the outside in the tire width direction, the sealant layer 50 can be positioned in a position in the tread portion 2 where a foreign object may penetrate, while preventing the sealant layer 50 from becoming too wide. This prevents an increase in the volume of components positioned on the tire cavity side and allows the sealant layer 50 to suppress air leakage when a foreign object penetrates the tread portion 2, thereby suppressing heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds and ensuring puncture sealing. As a result, the puncture sealing ability of the pneumatic tire 1 can be more reliably ensured, while also ensuring high-speed durability.

[0098] Furthermore, the sealant layer 50 is positioned such that its outer end 51 in the tire width direction is within a range of 0 mm to 10 mm outward in the tire width direction from the intersection P between the tire inner surface 18 and a perpendicular line L drawn from the end 145 of the belt layer 14 toward the tire inner surface 18, and the tire inner surface 18. This makes it possible to suppress an increase in the volume of the components arranged on the tire cavity side, while also preventing air leakage when a foreign object penetrates the tread portion 2, by the sealant layer 50.

[0099] In other words, if the end 51 of the sealant layer 50 is located less than 0 mm outward in the tire width direction from the intersection P of the perpendicular line L and the tire inner surface 18, the width of the sealant layer 50 in the tire width direction may be too narrow. In this case, if a foreign object such as a nail penetrates the tread portion 2 in a position closer to the shoulder portion 5 while the vehicle is running, the foreign object may penetrate into a position on the tire inner surface 18 that is further outward in the tire width direction than the portion where the sealant layer 50 is located, making it difficult for the sealant layer 50 to prevent air leakage from through holes created by the foreign object. Furthermore, if the end 51 of the sealant layer 50 is located more than 10 mm outward in the tire width direction from the intersection P of the perpendicular line L and the tire inner surface 18, the width of the sealant layer 50 in the tire width direction may be too wide. In this case, the volume of the sealant layer 50 tends to increase, which tends to increase the volume of the components disposed on the tire cavity side, which may make it difficult to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds.

[0100] In contrast, when the end 51 of the sealant layer 50 is located within a range of 0 mm to 10 mm outward in the tire width direction from the intersection P of the perpendicular line L and the tire inner surface 18, the sealant layer 50 can be positioned in a position in the tread portion 2 where a foreign object may penetrate, while preventing the sealant layer 50 from becoming too wide. This prevents an increase in the volume of components located on the tire cavity side, and allows the sealant layer 50 to suppress air leakage when a foreign object penetrates the tread portion 2. This makes it possible to suppress heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds, while ensuring puncture sealing performance. As a result, the puncture sealing performance of the pneumatic tire 1 can be more reliably ensured, while also ensuring high-speed durability.

[0101] Furthermore, because the glass transition temperature of the sealant layer 50 is in the range of -120°C to -40°C, the viscosity of the sealant layer 50 can be maintained even in low-temperature environments. As a result, puncture sealing performance can be ensured even in low-temperature environments.

[0102] Furthermore, because the glass transition temperature of the sealant layer 50 is lower than the glass transition temperature of the chip-shaped sound-absorbing material 60, the sealant layer 50 can be prevented from brittle fracture in extremely low temperature environments. Furthermore, because the glass transition temperature of the chip-shaped sound-absorbing material 60 is in the range of -60°C or higher and -40°C or lower, breakage of the chip-shaped sound-absorbing material 60 in low temperature environments can be prevented. As a result, the durability of the sealant layer 50 and the chip-shaped sound-absorbing material 60 in low temperature environments can be ensured.

[0103] Furthermore, because the sealant layer 50 contains silyl groups, the temperature dependency of the physical properties of the sealant layer 50 can be reduced, allowing the physical properties to be maintained over a wide temperature range. As a result, the sealant layer 50 is temperature independent from low to high temperatures and can maintain its self-sealant function, making the sealant layer 50 less likely to flow even at high temperatures and less likely to crack even at low temperatures. Furthermore, by reducing the temperature dependency of the physical properties of the sealant layer 50, the temperature dependency of the adhesiveness to the chip-shaped sound-absorbing material 60 can also be reduced, allowing the adhesiveness to the chip-shaped sound-absorbing material 60 to be maintained over a wide temperature range. As a result, both puncture sealing ability and durability can be achieved.

[0104] Furthermore, because the silicone-based composition that constitutes the sealant layer 50 is a two-component curing silicone, the viscosity of the silicone-based composition is low immediately after mixing the two components in the process of forming the sealant layer 50 on the tire inner surface 18. This makes it possible to apply the silicone-based composition at room temperature in the process of forming the sealant layer 50 on the tire inner surface 18, making it easy to form the sealant layer 50. As a result, manufacturing costs can be reduced.

[0105] Furthermore, in the manufacturing method of the pneumatic tire 1 according to this embodiment, the sealant layer 50 is formed by applying sealant from a sealant nozzle 74 to the tire inner surface 18 in the tread portion 2 of the pneumatic tire 1, so that a sealant layer 50 capable of ensuring puncture sealing properties can be formed.

[0106] Furthermore, in the manufacturing method of the pneumatic tire 1 according to this embodiment, chip-shaped sound-absorbing material 60 is dispersed on the sealant layer 50, and the dispersed chip-shaped sound-absorbing material 60 is rolled while applying pressure with a roller 90, thereby adhering the chip-shaped sound-absorbing material 60 to the sealant layer 50. This allows multiple chip-shaped sound-absorbing materials 60 to be arranged with a portion of each embedded in the tire cavity side of the sealant layer 50. This allows a sealant layer 50 that ensures puncture sealing to be formed on the tire inner surface 18, while multiple chip-shaped sound-absorbing materials 60 that can absorb cavity resonance generated in the tire cavity to be arranged. This allows the multiple chip-shaped sound-absorbing materials 60 to reduce noise caused by cavity resonance generated in the tire cavity during vehicle travel, while ensuring puncture sealing.

[0107] Furthermore, because the chip-shaped sound-absorbing material 60, which absorbs cavity resonance noise generated in the tire cavity, is relatively small in size, it is possible to suppress an increase in the volume of components placed on the tire cavity side when placing the sound-absorbing material on the tire inner surface 18. This makes it possible to suppress the volume of components that generate heat when the vehicle is traveling at high speeds, thereby suppressing heat generation in the pneumatic tire 1 when the vehicle is traveling at high speeds, and therefore suppressing a decrease in high-speed durability due to heat generation. As a result, it is possible to achieve both noise reduction and puncture sealing performance, while ensuring high-speed durability.

[0108] Furthermore, because the sealant of the sealant layer 50 is applied to the tire inner surface 18 at 70°C or below, it can be applied without increasing the sealant application temperature. This allows the sealant layer 50 to be disposed on the tire inner surface 18 without causing any thermal effects on the pneumatic tire 1, thereby preventing the rubber member from being over-vulcanized by heating during the formation of the sealant layer 50. As a result, the sealant layer 50 can be provided without affecting the characteristics of the pneumatic tire 1.

[0109] [Variations] In the above-described embodiment, a two-component curing silicone is used as an example of the silicone-based composition constituting the sealant of the sealant layer 50, but other silicone-based compositions may also be used as the sealant of the sealant layer 50. The type of sealant layer 50 is not important as long as it can exhibit puncture sealing properties when placed on the tire inner surface 18 in the tread portion 2.

[0110] In the above-described embodiment, a regular octahedron ( FIG. 3( a) ), a regular dodecahedron ( FIG. 3( b) ), and a regular tetrahedron ( FIG. 3( c) ) are given in FIG. 3 as examples of the shape of the chip-shaped sound-absorbing material 60, but the chip-shaped sound-absorbing material 60 may have other shapes. The chip-shaped sound-absorbing material 60 may have a shape other than a regular polyhedron, for example, a polyhedron with irregular faces, i.e., a messy polyhedron, or a polyhedron with recesses formed in the surface of the chip-shaped sound-absorbing material 60, resulting in unevenness. Regardless of the polyhedral shape, forming the chip-shaped sound-absorbing material 60 as a polyhedron can increase the contact area with the sealant layer 50 and the area of ​​the portion that absorbs cavity resonance noise, thereby effectively reducing noise from the pneumatic tire 1 when the vehicle is running.

[0111] [Example] 9A and 9B are tables showing the results of performance evaluation tests of pneumatic tires. Performance evaluation tests conducted on the above-described pneumatic tire 1 for a conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and a comparative pneumatic tire for comparison with the pneumatic tire 1 according to the present invention will be described below. The performance evaluation tests were conducted on sound absorption performance, puncture sealing performance, and high-speed durability.

[0112] For the performance evaluation tests, pneumatic tires with a tire nominal size of 265 / 45R21 108Y as specified by JATMA were used as test tires, and the tires were mounted on rim wheels with a rim size of 21 x 9 inches, and each evaluation test was carried out.

[0113] The evaluation method for each test item was as follows: for sound absorption performance, the air pressure of each test tire was adjusted to 230 kPa and it was mounted on a test vehicle, a passenger car with an engine displacement of 2500 cc, and the vehicle was driven on an asphalt test course at an average speed of 100 km / h. The sound pressure level of the noise collected by a microphone attached near the driver's window was measured, and the reciprocal of this measurement value was expressed as an index, with the conventional example described below being set at 100. For sound absorption performance, the higher the value, the greater the reduction in cavity resonance noise, indicating better sound absorption performance.

[0114] Regarding puncture sealing, the air pressure of each test tire was adjusted to 250 kPa and the tire was mounted on a test vehicle (a passenger car with an engine displacement of 2500 cc). A nail with a diameter of 5 mm was driven into the center of the tread in the tire width direction, and after driving 1000 km, the nail was removed and the tire was left for 24 hours, and the air pressure was measured again. The evaluation results of puncture sealing were evaluated by expressing the measured air pressure as an index, with the conventional example described below being set at 100. The higher the index, the less the air pressure loss and the better the puncture sealing.

[0115] For high-speed durability, the air pressure of each test tire was adjusted to 360 kPa, and an indoor drum testing machine (drum diameter: 1707 mm) was used to measure the speed at which failure occurred by increasing the tire speed at regular intervals under a load of 6.68 kN. The measured speed was expressed as an index, with the conventional example described below being set at 100. The higher the numerical value for high-speed durability, the less likely failure occurs, indicating superior high-speed durability.

[0116] The performance evaluation test was conducted on 22 types of pneumatic tires, including a conventional pneumatic tire which is an example of a conventional pneumatic tire, Examples 1 to 20 which are pneumatic tire 1 according to the present invention, and a comparative example which is a pneumatic tire compared to pneumatic tire 1 according to the present invention. Of these, the conventional example does not have a sealant layer disposed on the inner surface of the tire, and the sound-absorbing material is formed in a strip shape and extends in the circumferential direction of the tire. Meanwhile, the comparative example has a sealant layer disposed on the inner surface of the tire, but the sound-absorbing material is formed in a strip shape and extends in the circumferential direction of the tire, just like the conventional example.

[0117] In contrast, in all of Examples 1 to 20, which are examples of the pneumatic tire 1 according to the present invention, a sealant layer 50 is disposed on the tire inner surface 18, and the sound-absorbing material is a chip-shaped sound-absorbing material 60 formed in chip form. Furthermore, the pneumatic tires 1 according to Examples 1 to 20 are different from one another in the average particle size of the chip-shaped sound-absorbing material 60, the average thickness of the sealant layer 50, the amount of chip-shaped sound-absorbing material 60 embedded in the sealant layer 50 relative to the particle size of the chip-shaped sound-absorbing material 60, the shape of the chip-shaped sound-absorbing material 60, the filling rate of the chip-shaped sound-absorbing material 60 per unit projected area on the sealant layer 50, and the position of the end 51 of the sealant layer 50 relative to the width WB of the belt layer 14, which is measured outward in the tire width direction from the intersection P between the tire inner surface 18 and a perpendicular line L drawn from an end 145 of the belt layer 14 toward the tire inner surface 18.

[0118] In addition, in the examples where the value of the position of the end 51 of the sealant layer 50 relative to the width WB of the belt layer 14, measured from the intersection P of the perpendicular line L drawn from the end 145 of the belt layer 14 toward the tire inner surface 18 and the tire inner surface 18 to the outside in the tire width direction, is shown as a negative (-) value, this indicates that the position of the end 51 of the sealant layer 50 is located more inward in the tire width direction than the intersection P.

[0119] 9A and 9B, performance evaluation tests were conducted using these pneumatic tires 1. As a result, it was found that the pneumatic tires 1 according to Examples 1 to 20 were able to improve at least two or more of the performances of sound absorption performance, puncture sealing performance, and high-speed durability compared to the conventional tire. In other words, the pneumatic tires 1 according to Examples 1 to 20 were able to achieve both noise reduction and puncture sealing performance while also ensuring high-speed durability.

[0120] The present disclosure includes the following inventions. Invention[1] a tread portion extending in the tire circumferential direction and forming an annular shape; a sealant layer disposed on the tire inner surface in the tread portion; a plurality of chip-shaped sound absorbing materials disposed on the tire cavity side of the sealant layer, each of which is partially embedded in the sealant layer; A tire characterized by comprising: Invention[2] The tire according to invention [1], wherein the chip-shaped sound-absorbing material has an average particle size in the range of 1 mm or more and 10 mm or less. Invention[3] The tire according to the invention [1] or [2], wherein the sealant layer has an average thickness in the range of 2 mm to 5 mm. Invention[4] A tire according to any one of Inventions [1] to [3], wherein the amount of the chip-shaped sound-absorbing material embedded in the sealant layer is within the range of 30% to 50% of the particle size of the chip-shaped sound-absorbing material. Invention[5] The tire according to any one of the inventions [1] to [4], wherein the chip-shaped sound-absorbing material has a polyhedral shape. Invention[6] The tire according to any one of the inventions [1] to [5], wherein the chip-shaped sound-absorbing material is a porous body. Invention[7] The tire according to invention [6], wherein the chip-shaped sound-absorbing material is a porous body made of soft polyurethane foam. Invention[8] A tire according to any one of inventions [1] to [7], wherein the chip-shaped sound-absorbing material has a filling rate of 50% or more per projected unit area on the sealant layer. Invention[9] A belt layer is disposed in the tread portion, The tire according to any one of inventions [1] to [8], wherein an outer end portion in the tire width direction of the sealant layer is located at a position within a range of 0% to 10% of the width of the belt layer in the tire width direction, from a point of intersection of the tire inner surface and a perpendicular line drawn from the end portion of the belt layer in the tire width direction toward the tire inner surface, toward the outside in the tire width direction. Invention

[10] A belt layer is disposed in the tread portion, The tire according to any one of inventions [1] to [8], wherein the sealant layer has an outer end in the tire width direction that is located at a position within a range of 0 mm to 10 mm outward in the tire width direction from an intersection of a perpendicular line drawn from the end of the belt layer in the tire width direction toward the tire inner surface and the tire inner surface. Invention

[11] The tire according to any one of the inventions [1] to

[10] , wherein the sealant layer has a glass transition temperature in the range of -120°C or higher and -40°C or lower. Invention

[12] A tire according to any one of inventions [1] to

[11] , wherein the glass transition temperature of the sealant layer is equal to or lower than the glass transition temperature of the chip-shaped sound-absorbing material, and the glass transition temperature of the chip-shaped sound-absorbing material is in the range of -60°C or higher and -40°C or lower. Invention

[13] The tire according to any one of the inventions [1] to

[12] , wherein the sealant layer has a silyl group. Invention

[14] The tire according to any one of inventions [1] to

[13] , wherein the silicone composition constituting the sealant layer is a two-component curing silicone. Invention

[15] a step of applying a sealant from a sealant nozzle to an inner surface of a tire in a tread portion of the tire to form a sealant layer; a step of spraying chip-shaped sound-absorbing material onto the sealant layer from a sound-absorbing material nozzle; a step of applying pressure to the scattered chip-shaped sound-absorbing material with a roller and rolling the roller to adhere the chip-shaped sound-absorbing material to the sealant layer; A method for manufacturing a tire, comprising: Invention

[16] The method for manufacturing a tire according to the invention

[15] , wherein the sealant is applied to the inner surface of the tire at a temperature of 70°C or less. [Explanation of symbols]

[0121] 1 pneumatic tire 2 Tread section 3 Tread contact surface 4 Tread rubber 5 Shoulder section 8 Sidewall 10 Carcass layer 10a Carcass main body 10b Turn-up section 14 Belt Layer 16 Inner liner 17 Rim cushion rubber 18 Tire inner surface 20 Land 30 Circumferential groove 40 Bead section 41 Bead core 45 Bead Filler 50 sealant layer 51 End 52 Belt material 60 Chip sound absorbing material 71 Sealant extrusion device 72 Pump 73 Pump 74 Sealant Nozzle 81 Sound absorbing material spreading device 82 Sound-absorbing material supply section 83 Sound absorbing nozzle 90 Roller 91 Support member

Claims

1. a tread portion extending in the tire circumferential direction and forming an annular shape; a sealant layer disposed on the tire inner surface in the tread portion; a plurality of chip-shaped sound absorbing materials disposed on the tire cavity side of the sealant layer, each of which is partially embedded in the sealant layer; A tire characterized by comprising:

2. The tire according to claim 1, wherein the chip-shaped sound absorbing material has an average particle size in the range of 1 mm to 10 mm.

3. The tire according to claim 1, wherein the sealant layer has an average thickness in the range of 2 mm to 5 mm.

4. The tire according to claim 1 , wherein the amount of the chip-shaped sound-absorbing material embedded in the sealant layer is within a range of 30% to 50% of the particle size of the chip-shaped sound-absorbing material.

5. The tire according to claim 1 , wherein the chip-shaped sound absorbing material has a polyhedral shape.

6. The tire according to claim 1 , wherein the chip-shaped sound absorbing material is a porous material.

7. The tire according to claim 6, wherein the chip-shaped sound absorbing material is the porous body made of soft polyurethane foam.

8. The tire according to claim 1 , wherein the packing rate of the chip-shaped sound-absorbing material per unit projected area on the sealant layer is 50% or more.

9. A belt layer is disposed in the tread portion, 2. The tire according to claim 1, wherein an outer end portion in the tire width direction of the sealant layer is located at a position within a range of 0% to 10% of a width of the belt layer in the tire width direction, from an intersection of the tire inner surface and a perpendicular line drawn from an end portion of the belt layer in the tire width direction toward the tire inner surface, toward the outer side in the tire width direction.

10. A belt layer is disposed in the tread portion, 2. The tire according to claim 1, wherein an outer end portion in the tire width direction of the sealant layer is located at a position within a range of 0 mm to 10 mm outward in the tire width direction from an intersection of a perpendicular line drawn from an end portion of the belt layer in the tire width direction toward the tire inner surface and the tire inner surface.

11. 2. The tire according to claim 1, wherein the sealant layer has a glass transition temperature in the range of −120° C. or higher and −40° C. or lower.

12. 2. The tire according to claim 1, wherein the glass transition temperature of the sealant layer is equal to or lower than the glass transition temperature of the chip-shaped sound-absorbing material, and the glass transition temperature of the chip-shaped sound-absorbing material is in the range of −60°C or higher and −40°C or lower.

13. The tire of claim 1 , wherein the sealant layer comprises a silyl group.

14. The tire according to claim 1 , wherein the silicone composition constituting the sealant layer is a two-component curing silicone.

15. a step of applying a sealant from a sealant nozzle to an inner surface of a tire in a tread portion of the tire to form a sealant layer; a step of spraying chip-shaped sound-absorbing material onto the sealant layer from a sound-absorbing material nozzle; a step of applying pressure to the scattered chip-shaped sound-absorbing material with a roller and rolling the roller to adhere the chip-shaped sound-absorbing material to the sealant layer; A method for manufacturing a tire, comprising:

16. The method for manufacturing a tire according to claim 15, wherein the sealant is applied to the inner surface of the tire at a temperature of 70°C or less.

Images