JP2020104606A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which enables increase of a success rate of flat tire sealing while keeping road noise reduction effect.SOLUTION: A sound control body 12 formed by a sponge material is adhered to an inner peripheral surface 11s of a sealant layer 11 disposed on an inner peripheral surface 2s of a tread part 2. In the sound control body 12, an area S1 of a radial outer surface Fo adhered to the sealant layer 11 is smaller than an area S2 of a radial inner surface Fi.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire having both puncture sealing performance and road noise reduction performance.

The following Patent Document 1 proposes a pneumatic tire having both puncture sealing performance and road noise reduction performance. The proposed tire has a puncture-preventing sealant layer on the inner peripheral surface of the tread portion, and a sound damper made of a sponge material is adhered to the inner peripheral surface of the sealant layer.

However, it has been found that the success rate of the puncture seal is reduced in the above-mentioned tire in the following cases.

As shown in FIGS. 7A and 7B, when a foreign object a such as a nail penetrates the noise suppressor b, a part of the noise suppressor b is torn off by the foreign object a with the sealant c, and the sponge is sponged. It tends to be piece b1. Then, when the foreign matter a comes out of the tire, the sponge piece b1 is clogged in the puncture hole d. At this time, the sponge piece b1 blocks the inflow of the sealant c into the puncture hole d, while allowing the air e in the tire to permeate to the outside. This causes the puncture success rate to decrease.

JP, 2017-65673, A

Therefore, the present invention can suppress that the puncture hole cannot be sealed due to a sponge piece generated when a foreign object such as a nail penetrates the noise suppressor, and the success rate of the puncture seal while maintaining the road noise reduction performance. It is an object to provide a pneumatic tire that improves

The present invention has a sealant layer for puncture prevention on the inner peripheral surface of the tread portion,
And a pneumatic tire in which a noise suppressor made of a sponge material is bonded to the inner peripheral surface of the sealant layer,
The area S1 of the outer surface in the radial direction adhered to the sealant layer of the sound damper is smaller than the area S2 of the inner surface in the radial direction of the sound damper.

In the pneumatic tire according to the present invention, it is preferable that a tire axial width W1 of the radial outer surface of the noise damper is smaller than a tire axial width W2 of the radial inner surface of the noise damper.

In the pneumatic tire according to the present invention, the radial outer surface and the radial inner surface of the noise damper are flat surfaces, and the thickness T between the radial outer surface and the radial inner surface is 20 mm or more. preferable.

In the pneumatic tire according to the present invention, it is preferable that a tire axial width W1 of the radial outer surface of the noise damper is 50% or less of a tire axial width W0 of the sealant layer.

In the pneumatic tire according to the present invention, the sponge material preferably has a tensile strength of 100 kPa or more.

As described above, in the sound damping body adhered to the inner peripheral surface of the sealant layer, the area S1 of the outer surface in the radial direction of the sound damping body is smaller than the area S2 of the inner surface in the radial direction as described above.

Therefore, it is difficult for the nail to penetrate the noise suppressor outside and around the outer surface in the radial direction of the noise suppressor. As a result, when the nail penetrates the noise suppressor, a part of the noise suppressor is torn off and becomes a sponge piece. This can prevent the sponge piece from entering the puncture hole and failing to seal the puncture hole when the nail is pulled out. That is, the success rate of the puncture seal can be improved while maintaining the road noise reduction performance of the noise suppressor.

It is a meridian sectional view which shows one Example of the pneumatic tire of this invention. It is a circumferential direction sectional view of a pneumatic tire along a tire equatorial plane. It is a partial perspective view which shows a sound damper. It is sectional drawing which shows the effect by a sound damper. (A), (B) is sectional drawing which shows the other effect in a noise suppressor. It is a circumferential direction sectional view of a pneumatic tire which shows other examples of a sound control body. (A), (B) is sectional drawing explaining the problem in a prior art.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment is a tubeless tire, and includes a sealant layer 11 for puncture prevention disposed on the inner peripheral surface 2s of the tread portion 2 and the sealant layer 11 The sound damping body 12 adhered to the circumferential surface 11s.

In the inside of the pneumatic tire 1, in this example, a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a carcass 6 radially outside of the carcass 6 and inside the tread portion 2 are provided. The belt layer 7 located there is arranged.

The carcass 6 is formed from one or more (one in this example) carcass plies 6A having carcass cords arranged at an angle of, for example, 75 to 90° with respect to the tire circumferential direction. The carcass ply 6A includes a ply folded portion 6b formed by folding the bead core 5 from the inner side to the outer side in the tire axial direction at both ends of the ply body 6a extending between the bead cores 5 and 5. A bead apex rubber 8 for bead reinforcement extending from the bead core 5 outward in the tire radial direction is provided between the ply body 6a and the ply folded-back portion 6b.

The belt layer 7 is formed from a plurality of (for example, two) belt plies 7A and 7B having belt cords arranged at an angle of, for example, 10 to 40° with respect to the tire circumferential direction. The belt plies 7A and 7B are laminated with different inclination directions so that the belt cords intersect between the plies. For the purpose of improving the high-speed durability of the tire, a band layer (not shown) in which a band cord is spirally wound can be provided on the outer side in the radial direction of the belt layer 7.

An inner liner rubber layer 10 is arranged inside the carcass 6. The inner liner rubber layer 10 is made of air impermeable rubber such as butyl rubber and keeps the tire internal pressure airtight.

A sealant layer 11 is provided on the inner peripheral surface 2s of the tread portion 2. As the sealant material forming the sealant layer 11, the one described in Patent Document 1 is preferably adopted. Specifically, the sealant material of this example contains a rubber component, a liquid polymer, a crosslinking agent, and the like. The hardness (viscosity) is controlled by the rubber component and the amount of crosslinking. Further, as the control of the rubber component, the kinds and amounts of the liquid polymer, the plasticizer and the carbon black are adjusted. On the other hand, the type and amount of the crosslinking agent are adjusted to control the amount of crosslinking.

Butyl rubber such as butyl rubber and halogenated butyl rubber is adopted as the rubber component. As the rubber component, the butyl rubber and the diene rubber may be mixed, but from the viewpoint of fluidity and the like, the content of the butyl rubber in 100% by mass of the rubber component is 90% by mass or more. Is preferred.

As the liquid polymer, liquid polybutene, liquid polyisobutene, liquid polyisoprene, liquid polybutadiene, liquid poly α-olefin, liquid isobutylene, liquid ethylene α-olefin copolymer, liquid ethylene propylene copolymer, liquid ethylene butylene copolymer, etc. Can be mentioned. Among them, liquid polybutene is preferable from the viewpoint of imparting tackiness and the like.

The content of the liquid polymer is preferably 50 parts by mass or more, and more preferably 100 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 50 parts by mass, the tackiness may decrease. The upper limit of the content is preferably 400 parts by mass or less, more preferably 300 parts by mass or less. If it exceeds 400 parts by mass, the sealant material may flow during running.

Well-known compounds can be used as the crosslinking agent, but organic peroxides are preferable. By using butyl rubber or liquid polymer in the organic peroxide cross-linking system, the tackiness, sealing property, fluidity and processability are improved.

Examples of organic peroxides include acyl peroxides such as benzoyl peroxide, dibenzoyl peroxide, p-chlorobenzoyl peroxide, 1-butylperoxyacetate, t-butylperoxybenzoate, and t-butylperoxy. Peroxyesters such as phthalate, ketone peroxides such as methylethylketone peroxide, di-t-butylperoxybenzoate, alkyl peroxides such as 1,3-bis(1-butylperoxyisopropyl)benzene, t- Examples thereof include hydroperoxides such as butyl hydroperoxide, dicumyl peroxide, t-butyl cumyl peroxide and the like. Among them, acyl peroxides are preferable, and dibenzoyl peroxide is particularly preferable, from the viewpoint of tackiness and fluidity.

The content of the organic peroxide (crosslinking agent) is preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 0.5 parts by mass, the crosslink density will be low, and the sealant material may flow. The upper limit of the content is preferably 40 parts by mass or less, more preferably 20 parts by mass or less. If it exceeds 40 parts by mass, the crosslink density becomes high and the sealing property may be deteriorated.

A crosslinking aid (vulcanization accelerator), an inorganic filler, a plasticizer and the like can be appropriately added to the sealant material.

As the crosslinking aid (vulcanization accelerator), sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamine-based, aldehyde-amine-based, aldehyde-ammonia-based, imidazoline-based, xanthogenic acid-based, And a quinone dioxime compound (quinoid compound) or the like. The compounding amount of the crosslinking aid (vulcanization accelerator) is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the rubber component.

The inorganic filler can be selected from the group consisting of carbon black, silica, calcium carbonate, calcium silicate, magnesium oxide, aluminum oxide, barium sulfate, talc, mica and the like. The compounding amount of the inorganic filler is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The plasticizer can be selected from the group consisting of aromatic process oil, naphthene process oil, paraffin process oil and the like. The compounding amount of the plasticizer is preferably 1 to 40 parts by mass with respect to 100 parts by mass of the rubber component.

The sealant layer 11 is formed by applying a sealant material prepared by adjusting and mixing the above-mentioned materials to the inner peripheral surface 2s of the tread portion 2 of the tire which has been vulcanized and molded in advance. Preferably, as described in Patent Document 1, for example, a sealant material continuously extruded from a twin-screw kneading extruder is helically adhered to the inner peripheral surface 2s of the tread portion 2 of the rotating tire. By heating the tire to which the sealant material has been applied and vulcanizing the sealant material, the sealant layer 11 having excellent sealing properties is formed.

It is preferable that the formation range of the sealant layer 11 includes at least a region between the reference lines X in the tire radial direction passing through the tread ground contact edge Te.

The thickness of the sealant layer 11 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and the upper limit is preferably 10.0 mm or less, more preferably 8.0 mm or less, further preferably 5.0 mm or less. If the thickness is less than 1.0 mm, it becomes difficult to reliably close the puncture hole. On the other hand, even if it exceeds 10.0 mm, the effect of closing the puncture hole does not change so much, and rather causes a disadvantage of increasing the tire mass.

Further, a sound damper 12 made of a sponge material is bonded to the inner peripheral surface 11s of the sealant layer 11. In this example, the noise suppressor 12 is adhered by the adhesive force of the sealant material.

The area S1 of the radially outer surface Fo of the noise damper 12 is set smaller than the area S2 of the radially inner surface Fi. The radial outer surface Fo is a surface to which the noise suppressor 12 is bonded to the sealant layer 11. The radial inner surface Fi is a surface on which the noise damper 12 faces the inner side of the tire inner cavity H, and is substantially parallel to the radial outer surface Fo.

The areas S1 and S2 are defined as the areas of the surfaces when the irregularities are flattened when the surfaces of the radially outer surface Fo and the radially inner surface Fi have irregularities. That is, the areas S1 and S2 correspond to the areas on the assumption that the surface is not uneven. The irregularities include minute irregularities due to open cells and closed cells in the sponge material, and irregularities due to grooves, ribs, undulations, and the like.

In the present specification, a substantially flat surface having only minute irregularities due to open cells or closed cells of the sponge material is defined as a “flat surface”. In the present example, the radially outer surface Fo and the radially inner surface Fi are formed by “flat surfaces”.

As shown in FIG. 2, the noise suppressor 12 of the present example extends continuously in the tire circumferential direction, and both ends E in the tire circumferential direction abut each other. As a result, the noise damper 12 is formed as an annular body that is continuous in the tire circumferential direction. It should be noted that both ends E of the sound damper 12 may be separated from each other. In this case, the distance between the ends E in the tire circumferential direction is preferably 80 mm or less from the viewpoint of mass balance.

As the sponge material forming the sound damping body 12, a foamed body obtained by foaming rubber and synthetic resin is preferably adopted. Examples of the rubber foam include chloroprene rubber sponge, ethylene propylene rubber sponge, and nitrile rubber sponge. Examples of synthetic resin foams include polyurethane sponges (eg, ether polyurethane sponges, ester polyurethane sponges, ether/ester polyurethane sponges, etc.), polyethylene sponges (eg, polyethylene sponges, etc.), and the like. Above all, an ether/ester polyurethane sponge is suitable from the viewpoint of durability and quality stability.

In such a noise suppressor 12, bubbles on the surface or inside convert the vibration energy of air vibrating in the tire inner cavity into heat energy and consume it. Thereby, the cavity resonance energy can be reduced, that is, the cavity resonance sound can be absorbed to reduce the road noise.

The sponge material preferably has a density of 10 to 60 kg/m ³ . When the density is less than 10 kg/m ³ , the sound absorbing effect inside the sponge is lowered, while when it is more than 60 kg/m ³ , the sound is easily reflected on the sponge surface and the sound absorbing effect on the sponge surface is lowered. Both reduce the road noise reduction effect. Therefore, the lower limit of the density is preferably 20 kg/m ³ or more, and the upper limit is preferably 40 kg/m ³ or less.

As shown in FIG. 3, in the noise damper 12, the tire axial width W1 of the radial outer surface Fo is set to be smaller than the tire axial width W2 of the radial inner surface Fi in this example. As a result, the noise suppressor 12 has a cross section in a direction orthogonal to the length direction formed in a trapezoidal shape with the short side on the outer surface Fo side in the radial direction, particularly an isosceles trapezoidal shape.

Since W1<W2, the noise suppressor 12 is formed with an overhanging portion 12A that overhangs in the tire axial direction outside of the radial outer surface Fo.

As shown in FIG. 4, when the nail 20 is stabbed in a region Yo in which the radially inner surface Fi projects outward in the tire axial direction from the radially outer surface Fo, the noise suppressor 12 functions as follows. That is, the sound damping body 12 is deformed so that the projecting portion 12</b>A is flipped up by the nail 20 and prevents the nail 20 from penetrating the sound damping body 12. Therefore, it is possible to prevent a part of the noise suppressor 12 from being torn off and becoming a sponge piece. This can prevent the sponge piece from entering the puncture hole 21 and preventing the puncture hole 21 from being sealed when the nail 20 comes off.

The difference (W2-W1) between the axial width W1 in the tire axial direction and the axial width W2 in the tire axial direction is preferably 10 to 45 mm, and if it is less than 10 mm, the above-mentioned effect tends not to be sufficiently achieved. On the other hand, if it exceeds 45 mm, the fixing becomes unstable, and the noise damper 12 may fall over or the adhesive may come off.

The tensile strength of the sponge material (sound absorber 12) is preferably 100 kPa or more. As a result, it is possible to prevent the protruding portion 12A from breaking into pieces and becoming a sponge piece when it is flipped up. Further, it is possible to prevent the nail 20 from penetrating the overhanging portion 12A. The tensile strength of the sponge material was measured on a dumbbell-shaped test piece of No. 1 in conformity with "tensile strength and elongation" of item 10 defined in "Test method for flexible urethane foam" of JISK6400. The value.

The function is exhibited when the nail 20 is stuck in the area Yo.

Therefore, in order to reduce the chance that the nail 20 penetrates the noise damper 12, as shown in FIG. 1, the tire axial width W1 of the radial outer surface Fo of the noise damper 12 is set to the tire axial width W1 of the sealant layer 11. It is preferably reduced to 50% or less of W0. As described above, by setting the width W1 to be small, it is possible to reduce the chance that the nail 20 is stabbed in the region Yi that is the inner side in the tire axial direction with respect to the region Yo and penetrates the noise suppressor 12, and the success rate of puncture sealing is improved. It can be raised further. Further, it is also useful for suppressing the mass increase of the noise damper 12 and improving the rolling resistance performance.

In the noise suppressor 12, the thickness T between the radially outer surface Fo and the radially inner surface Fi is preferably 20 mm or more.

The average length of nails (foreign matter) confirmed in the market survey is 15 mm, and the maximum length is 30 mm. Considering the thickness of the tread portion 2, if the thickness T of the noise damper 12 is 20 mm or more, it is possible to prevent the noise damper 12 from penetrating even when the nail 20 is stuck in the area Yi. it can. Even if the nail 20 is stuck in the area Yi, it is possible to prevent the sound damper 12 from penetrating. As shown in FIGS. 5(A) and 5(B), when the nail 20 does not penetrate the noise damper 12, it is possible to prevent the nail 20 from tearing a part of the noise damper 12 to form a sponge piece. it can. This can prevent the sponge piece from entering the puncture hole 21 and preventing the puncture hole 21 from being sealed when the nail 20 comes off.

In consideration of the worn state of the tread portion 2 and the variation in the length of the nail 20 (foreign matter), the thickness T is preferably 25 mm or more. However, if the thickness T is too large, the mass increases, which is disadvantageous in terms of rolling resistance performance and cost. Therefore, the upper limit of the thickness T is preferably 60 mm or less, more preferably 40 mm or less.

FIG. 6 shows another embodiment of the pneumatic tire 1. In the present example, the plurality of noise dampers 12 are arranged side by side in the tire circumferential direction on the inner peripheral surface 11s of the sealant layer 11. In each of the sound dampers 12, the tire circumferential width Wc1 of the radially outer surface Fo is smaller than the tire circumferential width Wc2 of the radially inner surface Fi. As a result, the area S1 of the radially outer surface Fo is set smaller than the area S2 of the radially inner surface Fi. The tire axial width W1 and the tire circumferential width Wc1 of the radial outer surface Fo can be set smaller than the tire axial width W2 and the tire circumferential width Wc2 of the radial inner surface Fi, respectively.

Although the particularly preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the illustrated embodiments and can be modified into various modes.

A pneumatic tire (tire size: 215/55R17) having the basic structure shown in FIG. 1 and having a sound absorber having the specifications shown in Table 1 attached was prototyped, and the puncture success rate of each prototype tire (puncture seal Performance) and road noise reduction performance were evaluated.

An ether/ester polyurethane sponge (density 31 kg/m3) was used as each of the noise dampers. Except for the sound damper, each prototype tire has substantially the same specifications.

<Punk seal success rate>
Fifty nails (diameter: 5.2 mm, length: 40 mm) were uniformly dispersed and hammered into the following width region in the tread portion of the trial tire with the rim assembled and filled with the internal pressure (250 kPa). The width region is a width region in which the width in the tire axial direction centering on the tire equator is 108 mm, and corresponds to a region to which the noise suppressor of Comparative Example 1 is bonded. Then, after leaving it for 1 hour in an environment of room temperature of 25° C., the nail was pulled out and soap water was attached to the puncture hole to confirm the presence or absence of air leakage. The success rate of puncture seal was evaluated from the number of puncture holes without air leakage. The higher the number, the better.

<Road noise reduction performance>
The driver's window side when the prototype tires filled with the internal pressure (240 kPa) were mounted on all wheels of the vehicle (2000 cc, FF vehicle) and the road noise measurement road (asphalt rough road) was driven at a speed of 60 km/h. The in-vehicle sound at the ear position (air column resonance sound near the narrow band of 240 Hz) was evaluated by a sensory evaluation of the driver by an index with Comparative Example 1 being 100. The higher the number, the better.

As shown in the table, it can be confirmed that the example products can increase the success rate of puncture sealing while maintaining the road noise reduction effect.

The composition of the sealant material used for the sealant layer is shown in Table 2. The various chemicals shown in Table 2 are as follows.
-Butyl rubber: IIR065, manufactured by JSR Co., Ltd.-Polybutene: HV-1900, manufactured by JX Nikko Nikko Energy Co., Ltd., number average molecular weight 2900.
・Carbon black: N330, manufactured by Cabot Japan Co., Ltd. ・Oil: DOS (dioctyl sebacate), manufactured by Taoka Chemical Co., Ltd. ・Crosslinking agent: Niper NS (40% of BPO, 48% of DBP), manufactured by NOF CORPORATION ・Crosslinking aid : QO (quinone dioxime), manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

1 Pneumatic Tire 2 Tread 2s Inner Surface 11 Sealant Layer 11s Inner Surface 12 Noise Suppressor Fo Radial Outer Surface Fi Radial Inner Surface

However, it has been found that the success rate of the puncture seal is reduced in the above-mentioned tire in the following cases. As shown in FIGS. 7A and 7B, when a foreign object a such as a nail penetrates the noise suppressor b, a part of the noise suppressor b is torn off by the foreign object a with the sealant c, and the sponge is sponged. It tends to be piece b1. Then, when the foreign matter a comes out of the tire, the sponge piece b1 is clogged in the puncture hole d. At this time, the sponge piece b1 prevents the sealant c from flowing into the puncture hole d, while allowing the air e in the tire to permeate to the outside. And this causes the success rate of the puncture seal to decrease.
Therefore, the present invention can suppress that the puncture hole cannot be sealed due to the sponge piece generated when a foreign object such as a nail penetrates the noise suppressor, and the success rate of the puncture seal while maintaining the road noise reduction performance. It is an object to provide a pneumatic tire that improves

It is a meridian sectional view which shows one Example of the pneumatic tire of this invention. It is a circumferential direction sectional view of a pneumatic tire along a tire equatorial plane. It is a partial perspective view which shows a sound damper. It is sectional drawing which shows the effect by a sound damper. (A), (B) is sectional drawing which shows the other effect in a noise suppressor. It is a circumferential direction sectional view of a pneumatic tire which shows other examples of a sound control body. (A), (B) is sectional drawing explaining the subject which this invention tends to solve .

Claims (5)

Having a sealant layer for puncture prevention on the inner peripheral surface of the tread part,
And a pneumatic tire in which a noise suppressor made of a sponge material is bonded to the inner peripheral surface of the sealant layer,
The pneumatic tire in which the area S1 of the radial outer surface of the sound damper bonded to the sealant layer is smaller than the area S2 of the radial inner surface of the sound damper. The pneumatic tire according to claim 1, wherein a tire axial width W1 of the radial outer surface of the noise damper is smaller than a tire axial width W2 of the radial inner surface of the noise damper. The pneumatic tire according to claim 1 or 2, wherein a radial outer surface and a radial inner surface of the noise damper are flat surfaces, and a thickness T between the radial outer surface and the radial inner surface is 20 mm or more. The pneumatic tire according to any one of claims 1 to 3, wherein a tire axial width W1 of the radial outer surface of the noise damper is 50% or less of a tire axial width W0 of the sealant layer. The pneumatic tire according to claim 1, wherein the sponge material has a tensile strength of 100 kPa or more.

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