JP6880985B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire. More specifically, the present invention relates to a pneumatic tire that retroreflects the light when it is irradiated.

In the technical field related to automobiles, a collision avoidance system that detects the distance between a preceding vehicle and a following vehicle to avoid a collision between vehicles has been put into practical use, and precedes using an image acquired by a camera. A technique for estimating the distance between a vehicle to be driven and a vehicle following the vehicle is disclosed (Patent Document 1 and Patent Document 2).

Further, when estimating the distance between vehicles using an image acquired by a camera, a tire technology that can suppress a decrease in the vehicle recognition rate by the camera and suppress a collision between vehicles is disclosed (patented). Document 3).

U.S. Pat. No. 8,164,628 Japanese Unexamined Patent Publication No. 2013-101040 Japanese Unexamined Patent Publication No. 2016-94039

However, when the illuminance is low at night or in a tunnel, there is a problem that the contrast between the surroundings and the tire is low and the tire does not function as a feature point of image recognition.
Therefore, the present invention provides a pneumatic tire that can function as a feature point of image recognition even when the illuminance is low at night or in a tunnel.

The present inventions have found that the above problems can be solved by arranging an elastomer composition containing a transparent elastomer and a retroreflective optical element dispersed in the transparent elastomer on the surface of a pneumatic tire, and the present invention has been made. completed.
That is, the present invention is a pneumatic tire in which an elastomer composition containing a transparent elastomer and a retroreflective optical element dispersed in the transparent elastomer is arranged on the surface.

The present invention includes the following embodiments.
[1] A pneumatic tire having a layer of an elastomer composition containing a transparent elastomer and a retroreflective optical element dispersed in the transparent elastomer on at least a part of an outer surface.
[2] The retroreflective optical element is composed of a sphere having a diameter of 10 to 200 μm made of a transparent material and a reflective layer made of a continuous metal-deposited layer covering 30 to 70% of the surface of the sphere. The pneumatic tire according to [1].
[3] The elastomer composition contains a plurality of retroreflective optical elements having different coverage of the reflective layer on the surface of the sphere, and the coverage is distributed in the range of 30 to 50% [2]. ] The pneumatic tire described in.
[4] The air according to [2] or [3], wherein the elastomer composition contains a plurality of retroreflective optical elements having different diameters of the spheres, and the diameters are distributed in the range of 30 to 150 μm. Entering tire.
[5] The pneumatic tire according to any one of [1] to [4], wherein the retroreflective element is irregularly dispersed in the transparent elastomer.
[6] The pneumatic tire according to any one of [1] to [5], wherein the volume fraction of the retroreflective optical element in the elastomer composition is less than 50%.
[7] The transparent elastomer is at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, nitrile rubber, ethylene propylene rubber, urethane rubber and silicone rubber, [1] to [6]. ] The pneumatic tire described in any of.
[8] The pneumatic tire according to any one of [1] to [7], wherein the elastomer composition is crosslinked with a peroxide cross-linking agent.
[9] The pneumatic tire according to any one of [1] to [8], wherein the elastomer composition contains a silane coupling agent.
[10] The pneumatic tire according to any one of [1] to [9], wherein the concealment rate of the elastomer composition according to the method B (concealment rate test paper) of JIS K 5600-4-1 is 70% or less. ..
[11] The pneumatic tire according to any one of [1] to [10], wherein the elastomer composition contains an acid-modified polymer.
[12] The pneumatic tire according to any one of [1] to [11], wherein the elastomer composition contains a phenolic antioxidant.
[13] The pneumatic tire according to any one of [1] to [12], wherein the layer of the elastomer composition is arranged in a non-grounded portion.

The pneumatic tire of the present invention can function as a feature point of image recognition even when the illuminance is low at night or in a tunnel.

FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a retroreflective optical element.

The pneumatic tire of the present invention has a layer of an elastomer composition on at least a part of its outer surface.
FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention. The pneumatic tire 1 has a layer 2 of an elastomer composition on at least a part of its outer surface 3. In FIG. 1, the layer 2 of the elastomer composition is arranged at the bottom 6, the shoulder portion 7 and the sidewall portion 8 of the groove 5 of the tread portion 4, but the present invention is not limited to that embodiment. The layer 2 of the elastomer composition is preferably arranged in the non-grounded portion. The non-grounded portion is the portion of the outer surface of the pneumatic tire that does not come into contact with the road surface. Examples of the non-grounded portion include the outer surfaces of the bottom 6 of the groove 5 of the tread portion 4, the shoulder portion 7, the sidewall portion 8, and the bead portion 9, but the layer 2 of the elastomer composition is more preferable. Arranged on at least one outer surface of the tread groove bottom 6, shoulder 7 and sidewall 8, more preferably all outside of the tread groove bottom 6, shoulder 7 and sidewall 8. Placed on the surface.

The elastomer composition comprises a transparent elastomer and a retroreflective optical element.

The transparent elastomer means a transparent elastomer. Transparency means that when light is incident, it passes at least a part of the light. The elastomer is not limited as long as it is transparent, but is preferably at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, nitrile rubber, ethylene propylene rubber, urethane rubber and silicone rubber. More preferably, it is styrene-butadiene rubber, butadiene rubber, or isoprene rubber.

The hiding ratio of the transparent elastomer is not limited as long as it is transparent, but is preferably 70% or less, more preferably 0 to 50%, and further preferably 0 to 30%. The concealment rate is measured by Method B (concealment rate test paper) of JIS K 5600-4-1. If the hiding ratio of the transparent elastomer is too high, when light is incident on the layer of the elastomer composition, the light is absorbed by the transparent elastomer, so that the reflected light is weakened.

The retroreflective optical element refers to a member having a function of reflecting incident light and returning it to the direction of a light source (retroreflective function). The retroreflective optical element is not limited as long as it has a retroreflective function, but preferably has a reflective layer on a part of the surface of a sphere made of a transparent material, and more preferably has a diameter of 10 made of a transparent material. It is composed of a sphere having a size of about 200 μm and a reflective layer composed of a continuous metal-deposited layer covering 30 to 70% of the surface of the sphere.

FIG. 2 is a diagram showing an example of a retroreflective optical element. The retroreflective optical element 11 is composed of a sphere 12 and a reflective layer 13. When the retroreflective optical element 11 is irradiated with light from a light source, the incident light 14 is refracted when passing through the surface of the sphere, reflected by the reflecting surface 15 on the back side, and refracted when passing through the surface of the sphere again. Then, the reflected light 16 returns to the light source.

The transparent material is not limited as long as it allows at least a part of the light to pass through when irradiated with light, but preferably glass, acrylic resin, polycarbonate and the like can be exemplified, and glass is more preferable. When the transparent material contains glass, acrylic resin, polycarbonate or the like as the main component, additives other than the main component may be contained as long as the effects of the present invention are not impaired.

The hiding rate of the transparent material is not limited as long as it has a retroreflective function, but is preferably 70% or less, more preferably 0 to 50%, and further preferably 0 to 30%. The concealment rate is measured by Method B (concealment rate test paper) of JIS K 5600-4-1. If the hiding rate of the transparent material is too high, when the light is incident on the sphere, the light is absorbed by the transparent material, so that the reflected light is weakened.

The refractive index of the transparent material is not limited as long as it has a retroreflective function, but is preferably 1.2 to 2.5, more preferably 1.5 to 2.4, and even more preferably 1.8 to 2.4. It is 2.3. If the refractive index is too low, the reflected light does not return in the same direction as the incident light and the retroreflective performance deteriorates. Conversely, if the refractive index is too high, the reflected light does not return in the same direction as the incident light and the retroreflective performance deteriorates. ..

The sphere does not have to be a true sphere as long as it has a retroreflective function, but it is preferably a true sphere.
The diameter of the sphere is not limited as long as it has a retroreflective function, but is preferably 10 to 200 μm, more preferably 30 to 150 μm, and even more preferably 30 to 100 μm. If the diameter is too small, the retroreflective performance may decrease, and if it is too large, the fatigue durability of the elastomer composition may decrease.
The diameter of the spheres of the retroreflective optical elements contained in the elastomer composition does not have to be uniform, but rather a mixture of retroreflective optical elements of various diameters is preferable. More preferably, the diameter is distributed in the range of 30 to 150 μm. When retroreflective optical elements of various diameters are mixed, there is an advantage that the filling rate of the retroreflective optical elements contained in the elastomer composition can be increased.

The reflective layer is not limited as long as it has a retroreflective function, but is preferably composed of a metal vapor deposition layer. The metal constituting the vapor-deposited layer is not limited as long as it has a reflective function, but is preferably aluminum, silver, chromium, nickel, zinc, gold, platinum or the like, and more preferably aluminum.

The reflective layer is preferably continuous. When the reflective layer is continuous, it means that the reflective layer is not divided or missing.

The coverage of the reflective layer on the surface of the sphere is not limited as long as it has a retroreflective function, but is preferably 30 to 70%, more preferably 30 to 50%, and even more preferably 40 to 50%. , Most preferably 50%. If the coverage is too small, the area of the reflective layer is small and the retroreflective performance is deteriorated. On the contrary, if it is too large, the opening surface through which the incident light enters is small and the retroreflective performance is deteriorated. The coverage of the reflective layer is the ratio of the area of the reflective layer to the total surface area of the sphere.
The coverage of the reflective layer of the retroreflective optical element contained in the elastomer composition does not have to be uniform, but rather it is preferable that the retroreflective optical elements having the coverage of various reflective layers are mixed. More preferably, the coverage is distributed in the range of 30 to 50%. When retroreflective optical elements with various reflective layer coverages are mixed, deterioration of retroreflective performance can be suppressed when the retroreflective optical elements are irregularly dispersed in the elastomer composition. There are advantages.

Retroreflective optical elements are commercially available, and commercially available products can be used in the present invention. Examples of commercially available retroreflective optical elements include "Unibeads" metal vapor deposition products (UB-24MSJ) manufactured by Unitika Ltd.

Retroreflective optics are dispersed in a transparent elastomer. The retroreflective optical elements are preferably irregularly dispersed. Irregularity means that the orientation of the retroreflective optical element (the direction in which the surface of the sphere without the reflective layer faces) is not constant, and the distance between the retroreflective optical element and the retroreflective optical element is not constant. Say. The retroreflective sheet, which is formed by arranging the retroreflective optical elements in the same direction, has poor reflectance when the incident angle of light is large, but the retroreflective optical elements are dispersed in the transparent elastomer without being aligned. By doing so, retroreflective can be performed even if the incident angle of light is large.

The volume fraction of the retroreflective optical element in the elastomer composition is not limited as long as it has a retroreflective function, but is preferably less than 50%, more preferably 1% or more and less than 50%, and further preferably 15. ~ 30%. If the volume fraction of the retroreflective optical element is too small, the retroreflective performance may be insufficient, and conversely, if it is too large, the elastomer component may be reduced and the fatigue durability may be lowered.

The elastomer composition is preferably crosslinked. The cross-linking agent is not limited as long as it does not inhibit the effect of the present invention, but is preferably a peroxide cross-linking agent. Cross-linking with a peroxide cross-linking agent has an advantage that a decrease in transparency of the elastomer composition can be suppressed. Examples of peroxide cross-linking agents include ketone peroxide-based cross-linking agents, peroxyketal-based cross-linking agents, hydroperoxide-based cross-linking agents, dialkyl peroxide-based cross-linking agents, diacyl peroxide-based cross-linking agents, and peroxy ester-based cross-linking agents. Examples thereof include peroxydicarbonate-based cross-linking agents, among which 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexin-3, 2,5-Dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide and dicumyl peroxide are preferred. When the peroxide cross-linking agent is blended, the blending amount of the peroxide cross-linking agent is preferably 0.1 to 10.0 parts by mass, more preferably 0.1 to 10 parts by mass based on 100 parts by mass of the transparent elastomer. It is 5.0 parts by mass, more preferably 0.2 to 3.0 parts by mass.

The elastomer composition preferably comprises a silane coupling agent. The inclusion of the silane coupling agent has an advantage that the affinity between the retroreflective optical element and the elastomer component is improved and the fatigue durability is improved. Examples of the silane coupling agent include vinylsilane-based coupling agents, epoxysilane-based coupling agents, methacrylsilane-based coupling agents, mercaptosilane-based coupling agents, sulfasilane-based coupling agents, and the like. 3-Triethoxysilylpropyl) tetrasulfide, 3-mercaptopropyl (trimethoxysilane), 3-mercaptopropyl (triethoxysilane) are preferred. When the silane coupling agent is blended, the blending amount of the silane coupling agent is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, based on 100 parts by mass of the retroreflective optical element. , More preferably 5 to 20 parts by mass.

The elastomeric composition preferably comprises an acid-modified polymer. The inclusion of the acid-modified polymer has an advantage that the affinity between the retroreflective optical element and the elastomer component is improved and the fatigue durability is improved. Examples of the acid-modified polymer include acid-modified diene rubber and acid-modified polyolefin. Among them, maleic acid-modified ethylene-butene copolymer, maleic acid-modified ethylene-propylene copolymer, maleic acid-modified ethylene-octene copolymer and the like. , Maleic acid-modified ethylene-ethyl acrylate copolymer is preferable. When the acid-modified polymer is blended, the blending amount of the acid-modified polymer is preferably 1 to 100 parts by mass, more preferably 5 to 70 parts by mass, and further preferably 5 based on 100 parts by mass of the transparent elastomer. ~ 50 parts by mass.

The elastomer composition preferably contains a phenolic anti-aging agent. By containing a phenolic anti-aging agent, there is an advantage that an anti-aging effect can be obtained without lowering the transparency of the elastomer composition. Examples of the phenol-based anti-aging agent include monophenol-based anti-aging agent, bisphenol-based anti-aging agent, and polyphenol-based anti-aging agent. Among them, 2,2'-methylene-bis (4-methyl-6-tert-). Butylphenol), 2,2'-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 2,5-di-tert-butyl Hydroquinone, 2,5-di-tert-amyl hydroquinone, 2,6-di-tert-butyl-4-methylphenol, mono (or di or tri) (α-methylbenzyl) phenol are preferred. When the phenol-based anti-aging agent is blended, the blending amount of the phenol-based anti-aging agent is preferably 0.2 to 5.0 parts by mass, more preferably 0.5 to 5.0 parts by mass based on 100 parts by mass of the transparent elastomer. It is 4.0 parts by mass, more preferably 0.5 to 3.0 parts by mass.

The elastomer composition may contain additives such as oils and processing aids in addition to the above components as long as the effects of the present invention are not impaired.

The hiding ratio of the elastomer composition is not limited as long as it is transparent, but is preferably 70% or less, more preferably 0 to 50%, and further preferably 0 to 30%. The concealment rate is measured by Method B (concealment rate test paper) of JIS K 5600-4-1. If the hiding ratio of the elastomer composition is too high, when light is incident on the layer of the elastomer composition, the light is absorbed by the elastomer composition, so that the reflected light is weakened.

The layer thickness of the elastomer composition is not limited as long as the effects of the present invention are exhibited, but is preferably 0.05 to 2.0 mm, more preferably 0.05 to 1.0 mm, and even more preferably 0. .1 to 0.5 mm. If the layer is too thin, the retroreflective performance may be insufficient, and conversely, if the layer is too thick, it may affect the running performance of the tire when placed on the tire.

The method for producing a pneumatic tire of the present invention is not limited as long as the effect of the present invention is obtained, but can be produced, for example, as follows.
Transparent elastomers, retrocatoptric elements, peroxide cross-linking agents, silane coupling agents, acid-modified polymers, phenolic antioxidants and other additives, if necessary, are mixed and kneaded by conventional methods. To prepare an elastomer composition. The elastomer composition is formed into a sheet by a conventional method to prepare an elastomer composition sheet. Tire members such as inner liners, carcass, and treads are placed on a molding drum and laminated by a conventional method to produce a green tire. An elastomer composition sheet is attached to the non-grounded portion of the green tire and vulcanized by a conventional method to manufacture a pneumatic tire.

(1) Raw materials The raw materials used in the examples are as follows.
SBR (Styrene-butadiene rubber): "Nipol" (registered trademark) 1502 manufactured by Zeon Corporation, specific gravity 0.94 g / cm ³
BR (butadiene rubber): "Nipol" (registered trademark) BR1220 manufactured by Zeon Corporation, specific density 0.94 g / cm ³
IR (isoprene rubber): "Nipol" (registered trademark) IR2200 manufactured by Zeon Corporation, specific density 0.91 g / cm ³
Retroreflective optical element: Metal vapor deposition beads "UB-24MSJ" manufactured by Unitika Co., Ltd., diameter 45-63 μm, metal vapor deposition layer coverage 50%, specific density 4.2 g / cm ³
Glass beads: "Uni beads" manufactured by Unitika Ltd. UB-46M, diameter 63-90 μm, specific density 4.2 g / cm ³
Peroxide cross-linking agent A: "Percadox 14" manufactured by Kayaku Akzo Corporation, 1,3-bis (t-butylperoxyisopropyl) benzene, specific gravity 1.08 g / cm ³
Peroxide cross-linking agent B: "Kayahexa YD-E85" manufactured by Kayaku Akzo Corporation, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, specific gravity 0.89 g / cm ³
Sulfur: "Oil-treated sulfur" manufactured by Hosoi Chemical Industry Co., Ltd., specific density 1.57 g / cm ³
Vulcanization accelerator: "Noxeller DM" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., specific density 1.50 g / cm ³
Zinc oxide: "Zinc Oxide No. 3" manufactured by Shodo Chemical Industry Co., Ltd., specific density 5.60 g / cm ³
Stearic acid: "Industrial stearic acid" manufactured by Chiba Fatty Acid Co., Ltd., specific density 0.92 g / cm ³
Silane coupling agent: "KBE-846" manufactured by Shin-Etsu Chemical Co., Ltd., bis (3-triethoxysilylpropyl) tetrasulfide, specific density 1.07 g / cm ³
Acid-modified polymer: Maleic acid-modified ethylene-butene copolymer "Toughmer" (registered trademark) MH7010 manufactured by Mitsui Chemicals Co., Ltd., specific density 0.87 g / cm ³
Oil: Paraffin-based oil "Process Oil 123" manufactured by Showa Shell Sekiyu Co., Ltd., specific density 0.87 g / cm ³
Anti-aging agent: "Antage W-400" manufactured by Kawaguchi Chemical Industry Co., Ltd., 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), specific density 1.06 g / cm ³

(2) Preparation of Elastomer Composition Of the raw materials shown in Table 1, the raw materials excluding peroxide cross-linking agent, sulfur, and vulcanization accelerator were used with a B-type Banbury mixer (1.8L) manufactured by Kobe Steel Co., Ltd. After mixing for 5 minutes, the peroxide cross-linking agent, sulfur, and vulcanization accelerator were kneaded with an 8-inch test kneading roll machine (manufactured by Kansai Roll Co., Ltd.) for 4 minutes to obtain an elastomer composition.

(3) Preparation of Elastomer Composition Sheet A sheet was prepared from the prepared elastomer composition using an 8-inch test kneading roll machine (manufactured by Kansai Roll Co., Ltd.). The thickness of the elastomer composition sheet was 1 mm.

(4) Tire molding Tire members such as an inner liner, carcass, side tread, and cap tread were placed on a molding drum and laminated by a conventional method to prepare a green tire. The elastomer composition sheet prepared in (2) above is attached to the outer surface of the green tire at the portion from the sidewall of the tire to the shoulder and the bottom of the cap tread groove, vulcanized by a normal vulcanization molding method, and the shoulder from the sidewall. A 195 / 65R15 size pneumatic tire was manufactured in which the elastomer composition was arranged in the portion and the bottom of the cap tread groove.

(5) Evaluation of hiding rate The hiding rate was evaluated for the elastomer composition. The concealment rate test method was in accordance with JIS K 5600-4-1 Method B (concealment rate test paper). The prepared elastomer composition sheet was placed on a concealment rate test paper, and the tristimulus value Y according to JIS Z 8722 was measured at each of the four white and black test pieces of the test piece, and the average value YW (white ground) of each was measured. ) And YB (black ground) were calculated. Next, the hiding rate YB / YW of the test piece was calculated as a percentage from the average values YW and YB at each of the four locations, and used as the hiding rate. The results are shown in Table 1.

(6) Evaluation of retroreflective performance The retroreflective performance of pneumatic tires was evaluated. The evaluation method is as follows.
The produced pneumatic tire was assembled on a 15 × 6JJ rim and filled with air so that the internal pressure was 200 kPa. The pneumatic tire is erected upright in a dark place, a floodlight is installed so that the distance from the pneumatic tire is 10 m and the incident angle is 40 degrees, and the retroreflected light of the sidewall is visually observed at an observation angle of 1 degree. It was confirmed. When sufficient retroreflective light was observed, it was evaluated as ◯, when retroreflective light was observed but the reflected light was weak, it was evaluated as Δ, and when retroreflective light was not exhibited, it was evaluated as ×.
The results are shown in Table 1.

(7) Evaluation of fatigue durability Fatigue durability was evaluated for pneumatic tires. The evaluation method is as follows.
The manufactured pneumatic tire was mounted on an FF passenger car with a rim of 15 x 6JJ and an internal pressure of 200 kPa, and the displacement was 1800 cc. Those having a large amount of bead dropouts or cracks in the sex reflective member were evaluated as x, those with bead dropouts but few cracks were evaluated as Δ, and those with less bead dropouts and no cracks were evaluated as ◯.
The results are shown in Table 1.

From the above results, the tires in which the metal-deposited beads of Examples 1 to 6 were blended and the elastomer composition crosslinked with the peroxide cross-linking agent was arranged showed good retroreflective performance, and the metal-deposited beads of Example 7 were exhibited. However, the tire on which the sulfur-based vulcanized elastomer composition was arranged showed slightly inferior retroreflective performance. The tire on which the elastomer composition containing the usual glass beads of Comparative Example 1 was placed did not show retroreflective.
In addition, Examples 2 to 5 in which a silane coupling agent and an acid-modified polymer were blended and an appropriate amount of metal-deposited glass beads were blended had good durability, and more preferable results were obtained.

The pneumatic tire of the present invention can be suitably used for mounting on an automobile or the like.

1 Pneumatic tire 2 Layer of elastomer composition 3 Outer surface 4 Tread part 5 Groove 6 Groove bottom 7 Shoulder part 8 Side wall part 9 Bead part 11 Retroreflective optical element 12 Sphere 13 Reflective layer 14 Incident light 15 Reflective surface 16 reflected light

Claims (12)

A pneumatic tire having a layer of an elastomer composition on at least a portion of the outer surface that includes a transparent elastomer and retrocatoptric elements irregularly dispersed in the transparent elastomer. The retroreflective optical element is composed of a sphere having a diameter of 10 to 200 μm made of a transparent material and a reflective layer made of a continuous metal-deposited layer covering 30 to 70% of the surface of the sphere. Pneumatic tires described in. The second aspect of the present invention, wherein the elastomer composition contains a plurality of retroreflective optical elements having different coverage of the reflective layer on the surface of the sphere, and the coverage is distributed in the range of 30 to 50%. Pneumatic tires. The pneumatic tire according to claim 2 or 3, wherein the elastomer composition comprises a plurality of retroreflective optical elements having different diameters of the spheres, the diameters of which are distributed in the range of 30 to 150 μm. The pneumatic tire according to any one of claims 1 to 4 , wherein the volume fraction of the retroreflective optical element in the elastomer composition is less than 50%. Any one of claims 1 to 5 , wherein the transparent elastomer is at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, nitrile rubber, ethylene propylene rubber, urethane rubber and silicone rubber. Pneumatic tires as described in the section. The pneumatic tire according to any one of claims 1 to 6 , wherein the elastomer composition is crosslinked with a peroxide cross-linking agent. The pneumatic tire according to any one of claims 1 to 7 , wherein the elastomer composition contains a silane coupling agent. The pneumatic tire according to any one of claims 1 to 8 , wherein the concealment rate of the elastomer composition according to the method B (concealment rate test paper) of JIS K 5600-4-1 is 70% or less. The pneumatic tire according to any one of claims 1 to 9 , wherein the elastomer composition contains an acid-modified polymer. The pneumatic tire according to any one of claims 1 to 10 , wherein the elastomer composition contains a phenolic antioxidant. The pneumatic tire according to any one of claims 1 to 11 , wherein the layer of the elastomer composition is arranged in a non-grounded portion.

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