pneumatic tires

Abstract

A pneumatic tire is provided that can ensure sealing performance in low-temperature environments. In a pneumatic tire having a tread (1) that extends in a ring shape along the tire circumference, a pair of sidewall portions (2) disposed on both sides of the tread (1), and a pair of bead portions (4) disposed on the radially inner side of these sidewall portions (2), a sealant layer (20) is formed on the inner surface of the tire at the tread (1), such that the glass transition temperature of the sealant constituting the sealant layer (20) is below the glass transition temperature of the crown rubber material constituting the tread (1).

Description

Technical Field

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire at the tread area, and more specifically, to a pneumatic tire capable of ensuring sealing performance in low-temperature environments. 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, sealants constituting the sealant layer are typically rubber compositions 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). Furthermore, 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), requiring the mixing of a large amount of liquid polymer.

[0004] However, sealants containing a large amount of liquid polymer, as mentioned above, tend to have a high glass transition temperature (Tg), which may result in insufficient sealing performance at low temperatures. Furthermore, the sealant may crack during driving, making it difficult to ensure tire durability.

[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 can ensure sealing performance in low-temperature environments.

[0013] Methods for solving problems

[0014] The pneumatic tire of the present invention, which achieves the above-mentioned objective, comprises: a tread portion extending in a ring shape along the tire circumference; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed radially inside the sidewall portions of the tire. The tire is characterized in that a sealant layer is formed on the inner surface of the tire at the tread portion, and the glass transition temperature of the sealant constituting the sealant layer is below the glass transition temperature of the cap compound constituting the tread portion.

[0015] Invention Effects

[0016] Regarding the pneumatic tire of the present invention, since the glass transition temperature of the sealant constituting the sealant layer is below the glass transition temperature of the crown rubber constituting the tread layer, as described above, it is possible to prevent sealant peeling at low temperatures and ensure sealing performance. Furthermore, in the present invention, the "glass transition temperature" of each material (sealant, crown rubber, and inner liner rubber, described later) is defined as the peak temperature of the graph (tanδ temperature curve) plotted for each material relative to temperature (tanδ can be measured using a viscoelastic spectrometer at an initial strain of 10%, amplitude ±2%, and frequency of 20 Hz).

[0017] In this invention, it is preferable that, at the tread portion, the outer periphery of the inner liner layer and the sealant layer are adjacent, and the glass transition temperature of the sealant is lower than that of the inner liner rubber compound constituting the inner liner layer. By setting not only the glass transition temperature of the sealant constituting the sealant layer lower than that of the crown rubber compound constituting the tread portion, as described above, but also setting the glass transition temperature of the sealant constituting the sealant layer to a temperature lower than that of the inner liner rubber compound, a good balance of physical properties between the inner liner layer and the sealant layer is achieved, which is beneficial for preventing sealant peeling at low temperatures.

[0018] In this invention, it is preferable that the glass transition temperature of the sealant is below -60°C. By setting the glass transition temperature of the sealant to a sufficiently low temperature in this way, it is beneficial to prevent the sealant from peeling off at low temperatures and to ensure sealing performance.

[0019] In this invention, it is preferred that the sealant is composed of an organosilicon-based composition. Furthermore, it is preferred that the organosilicon-based composition is a two-component curable organosilicon. Regarding sealants composed of organosilicon-based compositions, due to their low glass transition temperature, excellent weather resistance, and low temperature dependence of physical properties, they are advantageous in preventing sealant peeling at low temperatures and ensuring sealing performance. In particular, two-component curable organosilicones have low viscosity immediately after mixing, allowing for application even at low temperatures.

[0020] In this invention, it is preferable that the tanδ of the sealant at 100°C is 0.5 or less. This prevents the sealant from deforming during driving and affecting tire balance.

[0021] In this invention, it is preferable that the tread portion is configured to have a belt layer containing belt cords inclined relative to the tire circumference. Preferably, the distance L from the belt layer to the sealant layer is 10 mm or less at all locations of the belt layer located radially innermost on the tire. This allows the sealant to flow easily into the belt layer when a foreign object such as a nail penetrates the tread portion, thus ensuring good puncture seal.

[0022] In this invention, it is preferable that a sound-absorbing element is provided along the tire circumference on the radially inner side of the sealant layer. In this case, the sound-absorbing element can be provided on the sealant layer after it has been applied at low temperatures, thus avoiding damage to the sound-absorbing element and maintaining its sound absorption effect well.

[0023] The pneumatic tire of the present invention can form a sealant layer by coating the inner surface of the tire at the tread area with a sealant composed of an organosilicon-based composition after manufacturing the pneumatic tire (excluding the sealant layer). Preferably, the temperature of the sealant applied to the inner surface of the tire is below 70°C. By lowering the temperature of the sealant applied to the inner surface of the tire in this way, thermal shrinkage of the belt cover layer caused by heating during the formation of the sealant layer can be suppressed, thereby reducing deformation in the pneumatic tire and improving its durability. Attached Figure Description

[0024] Figure 1 This is a meridional sectional view showing an inflatable tire constructed according to an embodiment of the present invention.

[0025] Figure 2 It is shown Figure 1 A cross-sectional view of the main parts of an inflatable tire.

[0026] Figure 3 It is shown Figure 1 A cross-sectional view of the manufacturing method of a pneumatic tire.

[0027] Figure 4 It is shown 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.

[0028] Figure 5 This is a meridional sectional view showing an inflatable tire constructed according to other embodiments of the present invention. Detailed Implementation

[0029] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the pneumatic tire of this embodiment includes: 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. Because... Figure 1 This is a radial sectional view, so it is not depicted, but the tread portion 1, sidewall portion 2, and bead portion 3 extend circumferentially along the tire and form a ring, thus constituting the basic ring-shaped structure of a pneumatic tire. The following uses... Figure 1 The description is basically based on the meridian cross-sectional shape shown in the figure, but each tire component extends in a ring shape along the tire circumference.

[0031] A carcass layer 4 is provided between a pair of bead portions 3. The carcass layer 4 includes multiple carcass cords extending radially along the tire and folding back from the inside to the outside in the tire width direction 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.

[0032] 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. In the belt layer 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 layer 7.

[0033] At least one belt reinforcement layer 8 is provided on the outer periphery of the belt layer 7 to improve high-speed durability. The belt reinforcement layer 8 can be, for example, a full-coverage layer covering the entire width of the belt layer 7 and an edge-coverage layer partially covering the ends of the belt layer 7, as shown in the figure. The belt reinforcement layer 8 includes reinforcing cords oriented along the tire circumferential direction. In the belt reinforcement layer 8, the angle of the reinforcing cords relative to the tire circumferential direction is set to, for example, 0° to 5°. The belt reinforcement layer 8 is preferably a seamless structure obtained by continuously winding a belt, formed by straightening and rubber-coating at approximately 0° relative to the tire circumferential direction. The reinforcing cords of the belt reinforcement layer 8 are preferably organic fiber cords such as nylon or polyethylene terephthalate (PET).

[0034] An inner liner 9 is provided along the tire carcass layer 4 on the inner surface of the tire. This inner liner 9 is a layer used to prevent air filled inside the tire from permeating to the outside of the tire. The inner liner 9 is, for example, composed of a rubber composition mainly composed of butyl rubber with air-permeability properties. Alternatively, it may be composed of a resin layer with a thermoplastic resin as the matrix. In the case of a resin layer, the elastomer component may also be dispersed in the thermoplastic resin matrix.

[0035] At the tread portion 1, a tread rubber layer 11 is disposed on the outer periphery of the aforementioned carcass layer 4, belt layer 7, and belt reinforcement layer 8. The tread rubber layer 11 may be a structure formed by stacking two types of rubber layers with different physical properties (a cap tread layer constituting the tread surface of the tread portion 1 and an under tread layer disposed on the inner periphery of the cap tread layer) in the radial direction of the tire. A sidewall rubber layer 12 is disposed on the outer periphery (outer side in the tire width direction) of the carcass layer 4 at the sidewall portion 2, and a rim cushion rubber layer 13 is disposed on the outer periphery (outer side in the tire width direction) of the carcass layer 4 at the bead portion 3.

[0036] The above-described internal tire structure illustrates a representative example of a pneumatic tire, but the tire of the present invention is not limited thereto. Various grooves, such as multiple main grooves extending in the tire circumferential direction and transverse grooves extending in the tire width direction, can be formed in the tread portion 1.

[0037] In the aforementioned pneumatic tire, a sealant layer 20 is formed on the inner surface of the tire (the inner circumferential side of the inner liner 9) at the tread portion 1 in a continuous manner along the tire circumference. The sealant in the sealant layer 20 can be composed of a rubber composition primarily based on butyl rubber or an organosilicon composition, with an organosilicon composition being particularly preferred. As the butyl rubber, for example, in addition to butyl rubber (IIR), halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) can also be used. The organosilicon composition comprises a synthetic polymer compound having a main framework realized by siloxane bonds.

[0038] When the sealant constituting the sealant layer 20 is composed of either the aforementioned rubber composition or a silicone-based composition, its glass transition temperature is set below, and preferably below, the glass transition temperature of the crown rubber compound constituting the tread 1. Furthermore, the crown rubber compound refers to the rubber (vulcanized rubber) constituting the tread 1 (particularly the crown tread layer) (in the case where the tread 1 does not have a laminated structure of a crown tread layer and a bottom tread layer, the rubber (vulcanized rubber) constituting the tread rubber layer 11 is the crown rubber compound). Because the sealant has a low glass transition temperature, delamination of the sealant in low-temperature environments can be prevented, and sealing performance can be ensured.

[0039] Preferably, the glass transition temperature of the sealant is not only lower than that of the crown rubber material, but also lower than that of the inner lining rubber material constituting the inner lining layer 9. This results in a good balance of properties between the adjacent inner lining layers and the sealant layer, which helps prevent sealant peeling at low temperatures. Furthermore, the inner lining rubber material refers to the rubber (vulcanized rubber) or resin constituting the inner lining layer 9.

[0040] The glass transition temperature of the sealant should satisfy the above-mentioned relationship, but preferably below -60°C, more preferably below -90°C, and even more preferably between -90°C and -120°C. By setting the glass transition temperature of the sealant to a sufficiently low temperature, it is beneficial to prevent the sealant from peeling off at low temperatures and to ensure sealing performance. If the glass transition temperature of the sealant exceeds -60°C, the effect of preventing the sealant from peeling off at low temperatures and ensuring sealing performance is limited. Furthermore, the glass transition temperature of the sealant can be set by adjusting the type and amount of liquid polymer (e.g., paraffin oil, aromatic oil) mixed into the rubber composition or silicone-based composition constituting the sealant.

[0041] In addition, the glass transition temperatures of the crown rubber and the inner lining rubber should satisfy the above relationship, without any particular limitation. However, it is advisable to set the glass transition temperature of the crown rubber to -20℃ to -60℃, and the glass transition temperature of the inner lining rubber to -30℃ to -60℃.

[0042] Regarding the sealant of the present invention, not only does the glass transition temperature satisfy the above-mentioned relationship, but the tanδ at 100°C is preferably 0.5 or less, more preferably 0.5 to 0.3. This prevents deformation of the sealant layer 20 during driving, thus avoiding any impact on tire balance. If the tanδ of the sealant at 100°C exceeds 0.5, handling stability decreases.

[0043] 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, with a belt layer 7 and a belt cover layer 8 embedded in the tread portion 1. Next, a sealant is applied to the inner surface of the tire (the inner circumferential side of the inner liner 9) at the tread portion 1 to form a sealant layer 20. At this time, the sealant satisfies the aforementioned physical properties and has good fluidity even at low temperatures, thus allowing the temperature of the sealant applied to the inner surface of the tire to be below 70°C. This suppresses thermal shrinkage of the belt cover layer 8 caused by heating during the formation of the sealant layer 20. If the temperature is above 70°C, the deformation of the pneumatic tire increases, and durability deteriorates. It is particularly preferable that the temperature of the sealant applied to the inner surface of the tire is below 40°C. From the viewpoint of fluidity at low temperatures, the sealant is preferably composed of an organosilicon-based composition. Furthermore, from the viewpoint of fluidity of the organosilicon-based composition, a lower limit of the temperature of the sealant applied to the inner surface of the tire is preferably 20°C.

[0044] Figure 3 Show Figure 1 The specific manufacturing method of pneumatic tires, Figure 4 A sealant layer 20 formed on the inner surface of the tire at the tread area is shown. Figure 3In 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 of the tire, the sealant strip 21 can be arranged in a spiral shape on the inner surface 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.

[0045] 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-curable silicones. Two-component curable silicones consist of a first component and a second component; the curing reaction begins by mixing these first and second 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.

[0046] 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.

[0047] In the aforementioned pneumatic tire, the width Ws of the sealant layer 20 is preferably 90% or more of the width Wb of the belt layer 7. By making the width Ws of the sealant layer 20 sufficiently larger than the width Wb of the belt layer 7, punctures in the pneumatic tire can be effectively prevented. Conversely, if the width Ws of the sealant layer 20 is less than 90% of the width Wb of the belt layer 7, the puncture resistance is reduced.

[0048] 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 preventing durability degradation due to increased tire weight. If the thickness S of the sealant layer 20 is less than 2.0 mm, puncture resistance decreases; conversely, if it is greater than 5.0 mm, durability may deteriorate due to increased tire weight. The thickness S of the sealant layer 20 is the overall average thickness. This average thickness of the sealant layer 20 can be determined, 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.

[0049] In the aforementioned pneumatic tires, such as Figure 2 As shown, in all parts of the belt layer 7 located on the innermost radial side of the tire, the distance (shortest distance) L from the belt layer 7 to the sealant layer 20 should preferably be less than 10 mm. This allows the sealant to flow easily into the belt layer 7 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 7 to the sealant layer 20 is greater than 10 mm, the puncture seal at those portions may become insufficient.

[0050] Figure 5 A pneumatic tire constructed according to other embodiments of the present invention is shown. Figure 5 In this embodiment, a sound-absorbing element 40 is provided along the tire circumference on the radially inner side of the sealant layer 20. The sound-absorbing element 40 is made of a porous material with continuous air bubbles and has predetermined sound-absorbing characteristics based on this porous structure. Foamed polyurethane is preferably used as the porous material for the sound-absorbing element 40. After the sealant layer 20 is formed, the sound-absorbing element 40 is adhered to the sealant layer 20 based on its adhesiveness. In this case, since the sound-absorbing element 40 is provided on the sealant layer 20 after it has been coated at low temperatures, damage to the sound-absorbing element 40 can be avoided, and its sound-absorbing effect can be well maintained.

[0051] The present invention will be further illustrated below by way of examples, but the scope of the present invention is not limited by these examples.

[0052] Example

[0053] Tires were manufactured for Comparative Examples 1-3 and Examples 1-5 as follows: the tire size was 255 / 45R19, and the sealant mixture, crown compound type, and inner liner compound type were different as shown in Table 1. Furthermore, the mixtures of the crown and inner liner compounds are shown in Tables 2 and 3, and their numbers are recorded in the material type column of Table 1. The sealant layer thickness S of all tires was set to 3 mm, and the distance L from the belt layer to the sealant layer was set to 8 mm.

[0054] Table 1 lists the glass transition temperatures (Tg) of the sealant, crown compound, and lining compound (unit: °C). The glass transition temperature (Tg) of each material is defined as the peak temperature at which the tanδ graph of each material relative to temperature is plotted (tanδ temperature curve). Regarding tanδ, it was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Co., Ltd.) at an initial strain of 10%, amplitude ±2%, and frequency of 20 Hz.

[0055] Furthermore, Table 1 records the tire failure temperature (the test temperature used in the evaluation of low-temperature sealing performance described later) determined by the following method.

[0056] Tire failure temperature

[0057] Each test tire was assembled onto a wheel with a rim size of 8.5J, and the air pressure was set to 230 kPa. The tire was then mounted on the test vehicle. Under test conditions of 0°C, the vehicle was driven at 60 km / h on a test surface with three φ9.5 mm cleats for 30 minutes. Then, the test temperature was decreased by 5°C every 30 minutes until the tire failed. The temperature at which the tire failed was recorded as the "tire failure temperature".

[0058] The low-temperature sealing performance of these test tires was evaluated using the following test methods, and the results are shown in Table 1.

[0059] Low temperature sealing

[0060] Each test tire was assembled onto a wheel with an 8.5J rim, and the tire pressure was set to 230 kPa. A φ5mm nail was driven into the main groove of the tire tread under the condition of the tire's "tire failure temperature". The tire was driven at 60 km / h for 1 hour with the nail inserted. Afterward, the nail was removed, and the tire pressure was measured after 24 hours of resting at the "tire failure temperature". The evaluation results are expressed in three levels.

[0061] 3: The air pressure after settling is above 200 kPa.

[0062] 2: The air pressure after settling is above 150 kPa and below 200 kPa.

[0063] 1: The air pressure after settling is less than 150 kPa

[0064] [Table 1]

[0065]

[0066] The types of raw materials used in Table 1 are shown below.

[0067] • Silicone rubber 1: Shin-Etsu Chemical Co., Ltd., KE-551-U

[0068] • Silicone rubber 2: Two-component cured silicone, DOWSIL SE930 manufactured by DOW Company

[0069] Butyl rubber: JSR Corporation, CHLOROBUTY L1066

[0070] ·Paraffin oil: Hakko K-350 manufactured by Kino Corporation

[0071] • Aromatic oil: Diana Process Oil (AH-58) manufactured by Idemitsu Kosan Co., Ltd.

[0072] [Table 2]

[0073]

[0074] [Table 3]

[0075]

[0076] The types of raw materials used in Tables 2 and 3 are shown below.

[0077] NR: Natural rubber, SIR20

[0078] •SBR1: Styrene-butadiene rubber, Nipol 1502 manufactured by Zen Corporation of Japan

[0079] •SBR2: Styrene-butadiene rubber, manufactured by Zion Corporation of Japan, Nipol 9548

[0080] •CB: Carbon black, Degussa-Huels carbon black N772

[0081] • Adhesive: YS resin PX1000 manufactured by Yasuharake Mikael Co., Ltd.

[0082] Butyl rubber: JSR Corporation, CHLOROBUTY L1066

[0083] • Processing oil: Diana Process Oil NP250 manufactured by Idemitsu Kosan Co., Ltd.

[0084] ・Paraffin oil: Hakko K-350 manufactured by Kino Co., Ltd.

[0085] • Sulfur: Micronized sulfur from Kinka printing ink manufactured by Tsurumi Chemical Industry Co., Ltd.

[0086] As shown in Table 1, Examples 1-5 exhibited excellent low-temperature sealing performance while preventing sealant peeling at low temperatures. On the other hand, regarding Comparative Examples 1-3, since the glass transition temperature of the sealant was higher than that of the crown adhesive, it could not achieve sufficient sealing performance at low temperatures.

[0087] Explanation of reference numerals in the attached figures

[0088] 1. Fetal face

[0089] 2. Side of the tire

[0090] 3. Bead area

[0091] 4. Fetal body layers

[0092] 5. Tire bead core

[0093] 6. Bead filling

[0094] 7. Belt layer

[0095] 8. Belt Covering Layer

[0096] 9. Inner Lining

[0097] 11. Tread rubber layer

[0098] 12 Sidewall rubber layers

[0099] 13. Rim buffer rubber layer

[0100] 20. Sealant layer

[0101] 40 sound absorbing parts

Claims

1. A pneumatic tire, comprising: a tread portion extending in a tire circumferential direction in a ring shape; a pair of side portions disposed on both sides of the tread portion; and a pair of bead portions disposed on a tire radial direction inner side of the side portions, characterized in that, a sealant layer is formed on a tire inner surface at the tread portion, and a glass transition temperature of a sealant constituting the sealant layer is lower than a glass transition temperature of a cap compound constituting the tread portion.

2. The pneumatic tire according to claim 1, characterized in that, at the tread portion, an inner liner layer is adjacent to an outer peripheral side of the sealant layer, and the glass transition temperature of the sealant is lower than a glass transition temperature of an inner liner compound constituting the inner liner layer.

3. The pneumatic tire according to claim 1 or 2, characterized in that, the glass transition temperature of the sealant is -60°C or lower.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that, the sealant is constituted by a silicone-based composition.

5. The pneumatic tire according to claim 4, characterized in that, the silicone-based composition is a two-component curable silicone.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that, a tan δ at 100°C of the sealant is 0.5 or lower.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that, a belt layer including belt cords inclined with respect to the tire circumferential direction is embedded at the tread portion, and a distance L from the belt layer to the sealant layer is 10 mm or lower at all portions of the belt layer located on a tire radial direction innermost side.

8. The pneumatic tire according to any one of claims 1 to 7, characterized in that, an acoustic member is provided along the tire circumferential direction on a tire radial direction inner side of the sealant layer.

9. A method of manufacturing a pneumatic tire, the method of manufacturing a pneumatic tire being a method of manufacturing the pneumatic tire according to any one of claims 1 to 8, characterized in that, after the pneumatic tire is manufactured except for the sealant layer, the sealant layer is formed by applying a sealant constituted by a silicone-based composition to a tire inner surface at the tread portion, and a temperature of the sealant applied to the tire inner surface is lower than 70°C. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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