Pneumatic tires

Abstract

To achieve sufficient air seal performance even if a foreign object penetrates through a tread part in a pneumatic tire in which a sealant layer and a sound suppressor are disposed on a tire inner cavity surface.SOLUTION: A pneumatic tire includes: a tread part 2; a sealant layer 10 disposed on a tire inner cavity surface 1i of the tread part 2; a porous sound suppressor 11 disposed at the inner side of the sealant layer 10 as seen in a tire radial direction; and a barrier part 12 which is disposed between the sealant layer 10 and the sound suppressor 11 and prevents a sealant liquid from penetrating through the sound suppressor 11. Strength of the barrier part 12 is 2 to 25 (N).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a pneumatic tire. [Background technology]

[0002] The following Patent Document 1 proposes a pneumatic tire having a puncture-preventing sealant layer on the inner peripheral surface of the tread portion, and a noise-damping body made of a sponge material attached to the inner peripheral surface of the sealant layer. This pneumatic tire exhibits puncture sealing performance and road noise reduction performance due to the sealant layer and the noise-damping body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-104606 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned pneumatic tire, the sealant liquid may penetrate into the sound-damping body over time, causing the sound-damping body itself to become sticky. In such a case, if a foreign object such as a nail penetrates the tread portion and reaches the sound-damping body, the sound-damping body tends to break easily. When the foreign object is pulled out of the tread portion, the broken pieces of the sound-damping body enter the through-holes of the tread portion together with the sealant liquid, causing a problem of reducing the air-sealing performance of the sealant liquid.

[0005] The present invention has been devised in consideration of the above-mentioned circumstances, and has as its main objective to provide a pneumatic tire having a sealant layer and a noise-damping body on the tire inner cavity surface that exhibits sufficient air sealing performance even when a foreign object penetrates the tread portion. [Means for solving the problem]

[0006] The present invention is a pneumatic tire including a tread portion, comprising: a sealant layer containing an adhesive sealant liquid disposed on the tire cavity surface of the tread portion; a porous noise-damping body disposed radially inward of the sealant layer; and a barrier portion disposed between the sealant layer and the noise-damping body and preventing the sealant liquid from penetrating into the noise-damping body, the strength of the barrier portion being 2 to 25 (N).

[0007] In the pneumatic tire of the present invention, it is preferable that the barrier portion is a surface of the noise damper that has been made non-porous.

[0008] In the pneumatic tire of the present invention, the surface is preferably a surface to be heat treated.

[0009] In the pneumatic tire of the present invention, it is preferable that the barrier portion is an adhesive tape.

[0010] In the pneumatic tire of the present invention, the barrier portion is preferably a resin film.

[0011] In the pneumatic tire of the present invention, it is preferable that the noise damper is in close contact with the barrier portion via an adhesive.

[0012] In the pneumatic tire of the present invention, the specific gravity of the sound damper is 20 to 8 0 It is desirable to have one.

[0013] In the pneumatic tire of the present invention, the noise damper desirably has a thickness of 25 to 40 mm.

[0014] In the pneumatic tire of the present invention, the length of the noise damper in the axial direction of the tire is desirably 60% or more of the length of the sealant layer in the axial direction of the tire.

[0015] In the pneumatic tire of the present invention, it is desirable that the length of the noise damper in the axial direction of the tire is less than 100% of the length of the sealant layer in the axial direction of the tire.

[0016] In the pneumatic tire of the present invention, the barrier portion preferably has a thickness of 0.05 to 0.20 mm.

[0017] In the pneumatic tire of the present invention, it is preferable that the barrier portion covers a side surface of the noise damper in the tire axial direction.

[0018] In the pneumatic tire of the present invention, it is preferable that the barrier portion does not cover an inner circumferential surface of the noise damper in the tire radial direction.

[0019] In the pneumatic tire of the present invention, the barrier portion may cover a part of an inner circumferential surface of the noise damper in a radial direction of the tire. Effect of the Invention

[0020] By employing the above-described configuration, the pneumatic tire of the present invention can exhibit sufficient air sealing performance even if a foreign object penetrates the tread portion. [Brief description of the drawings]

[0021] [Figure 1] 1 is a tire meridian cross-sectional view showing one embodiment of a pneumatic tire of the present invention. [Diagram 2] FIG. 2 is an enlarged view of the tread portion of FIG. [Diagram 3] FIG. 11 is an enlarged cross-sectional view of a sound damper and a barrier portion according to another embodiment of the present invention. [Figure 4] FIG. 11 is an enlarged cross-sectional view of a sound damper and a barrier portion according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a tire meridian cross-sectional view of a pneumatic tire (hereinafter, sometimes simply referred to as "tire") 1 in a normal state, showing one embodiment of the present invention. In this embodiment, a pneumatic tire 1 for passenger cars is shown as a preferred embodiment. However, the present invention may also be adopted as a pneumatic tire 1 for motorcycles or heavy loads, for example.

[0023] In the case of a pneumatic tire for which various standards are established, the "normal state" refers to a state in which the tire is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established, the normal state refers to a standard use state according to the intended use of the tire, in which the tire is not mounted on a vehicle and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal state.

[0024] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "Design Rim," and in the case of ETRTO, it is called a "Measuring Rim."

[0025] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system on which the tire is based. In the case of JATMA, it is the "maximum air pressure." In the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." In the case of ETRTO, it is the "INFLATION PRESSURE."

[0026] As shown in Fig. 1, conventional tire components such as a carcass 6 and a belt layer 7 are arranged inside a tire 1 of this embodiment. Known embodiments can be appropriately adopted for these tire components.

[0027] The carcass 6 extends from the bead portion 4 on one side through the sidewall portion 3 on one side, the tread portion 2, and the sidewall portion 3 on the other side to the bead portion 4 on the other side. The carcass 6 has at least one carcass ply 6A, two in this embodiment. The carcass ply 6A is formed, for example, by covering an array of carcass cords with a topping rubber. The carcass cords are arranged, for example, at an angle of 75 to 90° with respect to the tire circumferential direction. For the carcass cords, organic fibers such as polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers are used.

[0028] The carcass ply 6A includes, for example, a main body portion 6a and a turned-up portion 6b. The main body portion extends from the tread portion 2 through the sidewall portion 3 to the bead core. The turned-up portion 6b is connected to the main body portion 6a and is turned around the bead core from the axially inner side to the outer side to extend radially outward.

[0029] The belt layer 7 is disposed on the tire radial direction outer side of the carcass 6 in the tread portion 2. The belt layer 7 includes at least one belt ply, and the belt layer 7 in this embodiment is composed of two belt plies 7A and 7B. The belt plies 7A and 7B are formed, for example, by covering an arrangement of belt cords with a topping rubber.

[0030] Fig. 2 shows an enlarged view of the tread portion 2. As shown in Fig. 2, the tire 1 of the present invention has a self-repairing sealant layer 10 disposed on the tire inner cavity surface 1i of the tread portion 2. The sealant layer 10 contains an adhesive sealant liquid. For example, when a foreign object such as a nail penetrates the tread portion 2 to cause a through hole, the sealant layer 10 hardens to seal the hole and prevents air from escaping from the tire.

[0031] In the tire 1 of the present invention, a porous noise-damping body 11 is disposed on the radially inner side of the sealant layer 10. This noise-damping body 11 can absorb air vibrations inside the tire while it is running, and is useful for reducing noise generated by the tire.

[0032] The tire 1 of the present invention includes a barrier portion 12 that is disposed between the sealant layer 10 and the noise damping body 11 and prevents the sealant liquid from penetrating into the noise damping body 11. The strength of the barrier portion 12 is 2 to 25 (N).

[0033] The strength of the barrier section 12 means the strength measured by a piercing strength test specified in JIS 1707. That is, the strength is the maximum force (N) required for a needle to penetrate a test piece fixed in a jig and pierced with a semicircular needle having a diameter of 1.0 mm and a tip radius of 0.5 mm at a test speed of 50±5 mm / min.

[0034] By adopting the above-mentioned configuration, the tire 1 of the present invention can exhibit sufficient air sealing performance even if a foreign object penetrates the tread portion 2. The following mechanism is presumed to be the reason for this.

[0035] In general, a tire having a sealant layer and a sound-damping body on the tire cavity surface can reduce noise during normal driving and can provide air-sealing performance when a foreign object is stuck in the tread portion 2. However, in the past, there was a problem that the sealant liquid penetrated into the sound-damping body, which was prone to partial breakage. In addition, when the sound-damping body breaks, when a through hole occurs in the tread portion, pieces of the sound-damping body enter the through hole, which reduces the air-sealing performance.

[0036] The tire 1 of the present invention includes the above-mentioned barrier portion 12, and therefore can effectively prevent the sealant liquid from penetrating into the sound-damping body 11, thereby suppressing the above-mentioned problems. In addition, since the strength of the barrier portion 12 is specified to be 2N or more, the barrier portion 12 has sufficient durability and can maintain air-sealing performance for a long period of time. In addition, since the strength of the barrier portion 12 is specified to be 25N or less, the barrier portion 12 has appropriate flexibility. Therefore, even if the tire inner cavity surface 1i is deformed, the barrier portion 12 easily conforms to the sound-damping body 11, and peeling of the barrier portion 12 is suppressed, and the sealant liquid can be reliably suppressed from penetrating into the sound-damping body 11. In addition, the flexible barrier portion 12 has excellent processability during tire manufacturing, and can also contribute to reducing the defective rate during production.

[0037] A more detailed configuration of this embodiment will be described below. Each configuration described below shows a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-mentioned effects even if it does not have the configuration described below. In addition, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-mentioned characteristics, an improvement in performance corresponding to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a composite improvement in performance corresponding to each configuration can be expected. In addition, the dimensions of each part described below refer to the dimensions when the tire is not mounted on a rim, the distance between the two bead cores is the same as the normal state, and no load is applied.

[0038] The sealant layer 10 is disposed, for example, on the inner surface of the tread portion 2, but a part of it may be disposed on the inner surface of the sidewall portion 3 (shown in FIG. 1), thereby further improving the air sealing performance.

[0039] The thickness of the sealant layer 10 is, for example, 1.0 to 5.0 mm, and preferably 2.0 to 4.0 mm, although the thickness of the sealant layer 10 is not limited to such a range.

[0040] As the main component of the rubber composition constituting the sealant liquid, for example, a butyl-based rubber is used. As the liquid polymer in the sealant liquid, liquid polybutene, liquid polyisobutene, etc. are used. As the curing agent in the sealant liquid, for example, an organic peroxide is used. However, the present invention is not limited to such an embodiment, and known materials can be appropriately adopted for the sealant liquid contained in the sealant layer 10.

[0041] The noise damper 11 is disposed, for example, in the center of the tread portion 2 in the tire axial direction. The noise damper 11 in this embodiment has a rectangular cross-sectional shape, and extends around the entire tire circumference with a constant cross-sectional shape. However, the noise damper 11 is not limited to this form. In the present invention, for example, a plurality of noise dampers 11 may be disposed on the tire cavity surface 1i, spaced apart in the tire circumferential direction or the tire axial direction. Also, various forms may be adopted for the cross-sectional shape of the noise damper 11.

[0042] The length L2 of the noise damper 11 in the tire axial direction is, for example, 60 to 100 mm, and preferably 70 to 90 mm. In a preferred embodiment, the length L2 of the noise damper 11 is less than 100% of the length L1 of the sealant layer 10 in the tire axial direction, and the length L2 of the noise damper 11 is preferably 60% or more of the length L1 of the sealant layer 10. This improves noise performance and air sealing performance in a well-balanced manner.

[0043] If the thickness t1 of the noise damper 11 is small, the noise damper 11 may be easily damaged and the air sealing performance may be reduced. If the thickness of the noise damper 11 is excessively large, the improvement in noise performance may saturate, but the tire weight may increase. From this viewpoint, the thickness t1 of the noise damper 11 is, for example, 25 to 50 mm, and preferably 30 to 40 mm.

[0044] If the specific gravity of the noise damper 11 is too low, the durability of the noise damper 11 may decrease. If the specific gravity of the noise damper 11 is too high, the tire weight may increase. From this viewpoint, the specific gravity of the noise damper 11 is set to, for example, 20 to 8 0 Yes, preferably 30-5 0 However, the noise damper 11 is not limited to this embodiment.

[0045] The barrier section 12 may be configured in various ways. In this embodiment, the barrier section 12 is configured, for example, of a resin film. Examples of materials for the resin film include polyethylene, polypropylene, PET, and polystyrene. As another material for the barrier section 12, a nonwoven fabric may be used.

[0046] In this embodiment, the sound damper 11 is in close contact with the barrier portion 12 made of a resin film via an adhesive. As the adhesive, a rubber-based, urethane resin-based, or modified silicone resin-based adhesive is preferably used. In another embodiment, the sound damper 11 may be in close contact with the barrier portion 12 via a rubber-based, acrylic-based, or silicone-based pressure-sensitive adhesive.

[0047] In another embodiment, an adhesive tape may be used as the barrier portion 12. That is, the sound-damping body 11 may be attached to the sealant layer 10 via an adhesive tape. In such an embodiment, the core material (resin film or nonwoven fabric) of the adhesive tape can suppress the above-mentioned penetration, and the same effect can be obtained.

[0048] The barrier portion 12 may be the surface of the noise damper 11 that has been made non-porous. In this embodiment, the noise damper 11 can be used as the material for the barrier portion 12, thereby reducing the manufacturing cost of the tire. Methods for making the surface of the noise damper 11 non-porous include heat treatment and chemical treatment. That is, the surface of the noise damper 11 may be made non-porous by being subjected to heat treatment or chemical treatment.

[0049] From the viewpoint of reliably suppressing the above-mentioned penetration, it is desirable that the length L3 of the barrier portion 12 in the tire axial direction is greater than the length of the outer circumferential surface of the noise damping body 11 in the tire axial direction. This makes it possible to prevent the noise damping body 11 from coming into contact with the sealant layer 10 even if the noise damping body 11 is deformed by the centrifugal force of the tire rotation. Furthermore, as described later, the barrier portion 12 may be disposed in other portions, such as the side surface of the noise damping body 11.

[0050] The strength of the barrier section 12 is preferably 5 N or more, more preferably 10 N or more, and is preferably 20 N or less, more preferably 15 N or less. The thickness t2 of the barrier section 12 is, for example, 0.05 to 0.20 mm, and preferably 0.10 to 0.15 mm. This can further improve the air sealing performance.

[0051] Fig. 3 shows an enlarged view of a noise damper 11 and a barrier portion 12 according to another embodiment of the present invention. As shown in Fig. 3, the barrier portion 12 according to this embodiment is disposed so as to cover not only between the sealant layer 10 and the noise damper 11, but also the entire side surface of the noise damper 11 in the tire axial direction and a part of the inner peripheral surface 11i of the noise damper 11. Such a barrier portion 12 suppresses damage to the side surface of the noise damper 11 and improves air sealing performance.

[0052] In order to achieve the above-mentioned effects while ensuring the vibration absorption performance of the noise damper 11, the area of ​​the barrier portion 12 arranged on the inner surface 11i of the noise damper 11 is 50% or less of the entire area of ​​the inner surface 11i of the noise damper 11 (including the portion covered by the barrier portion 12), and is preferably 5% to 25%.

[0053] Fig. 4 shows an enlarged view of a noise damping body 11 and a barrier portion 12 in still another embodiment of the present invention. As shown in Fig. 4, the barrier portion 12 in this embodiment is disposed between the sealant layer 10 and the noise damping body 11, and so as to cover the entire side surface of the noise damping body 11 in the tire axial direction. On the other hand, the barrier portion 12 in this embodiment does not cover the inner circumferential surface 11i of the noise damping body 11. In this embodiment, it is possible to ensure a large vibration absorbing surface of the noise damping body 11 while suppressing damage to the side surface of the noise damping body 11.

[0054] Although the pneumatic tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment and can be modified and implemented in various aspects. EXAMPLES

[0055] A pneumatic tire having a size of 215 / 55R17 and having the basic structure shown in FIG. 1 and based on the specifications in Tables 1 and 2 was manufactured. In addition, a pneumatic tire having no barrier portion was manufactured as a comparative example. The comparative tire was substantially the same as the tire of the embodiment, except for the above-mentioned points. The thickness of the sealant layer was 3.0 mm in all the test tires. The length of the sealant layer in the tire axial direction was 186 mm in all the test tires. The air sealing performance of these test tires was tested. The common specifications and test methods of each test tire are as follows. Rim: 17×7.5J Tire pressure: 250kPa

[0056] <Air seal performance> The test tire was loaded with a vertical load of 4.6 kN on a drum tester and run at a speed of 200 km / h for 1 hour. After that, 50 nails (diameter 5.0 mm) were driven into the tread. After these nails were removed, the number of places where the air seal effect of the sealant layer was exerted (places where air leakage had stopped) was counted. The results show that the higher the number, the better the air seal performance. The test results are shown in Tables 1-2.

[0057] [Table 1]

[0058] [Table 2]

[0059] As shown in Tables 1 and 2, it was confirmed that the tires of the examples exhibited sufficient air sealing performance even when a foreign object penetrated the tread portion. [Explanation of symbols]

[0060] 2 Tread section 1i Tire inner cavity surface 10 Sealant Layer 11 Sound damping body 12 Barrier section

Claims

1. A pneumatic tire including a tread portion, a sealant layer including a sealant liquid having adhesive and disposed on a tire cavity surface of the tread portion; a porous noise-damping body disposed on the inner side of the sealant layer in the tire radial direction; a barrier portion disposed between the sealant layer and the sound-damping body and preventing the sealant liquid from penetrating into the sound-damping body, The barrier portion has a strength of 2 to 25 (N) as measured by a puncture strength test specified in JIS 1707, The barrier portion covers a side surface of the noise damper in the tire axial direction and covers a part of an inner peripheral surface of the noise damper in the tire radial direction. Pneumatic tires.

2. The pneumatic tire according to claim 1 , wherein the barrier portion is a surface of the noise damper that has been made non-porous.

3. The pneumatic tire according to claim 2 , wherein the surface is a surface to be heat treated.

4. The pneumatic tire according to claim 1 , wherein the barrier portion is an adhesive tape.

5. The pneumatic tire according to claim 1 , wherein the barrier portion is a resin film.

6. The pneumatic tire according to claim 5 , wherein the noise damper is in close contact with the barrier portion via an adhesive.

7. 7. The pneumatic tire according to claim 1, wherein the specific gravity of the sound damper is 20 to 80.

8. 8. The pneumatic tire according to claim 1, wherein the noise damper has a thickness of 25 to 40 mm.

9. 9. The pneumatic tire according to claim 1, wherein a length of the noise damper in the tire axial direction is 60% or more of a length of the sealant layer in the tire axial direction.

10. The pneumatic tire according to claim 1 , wherein a length of the noise damper in the tire axial direction is less than 100% of a length of the sealant layer in the tire axial direction.

11. 11. The pneumatic tire according to claim 1, wherein the barrier portion has a thickness of 0.05 to 0.20 mm.

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