JP7230498B2 - pneumatic tire - Google Patents

Description

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

Patent Literature 1 below 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 damping body made of a sponge material is adhered to the inner peripheral surface of the sealant layer.

JP 2017-65673 A

However, it has been found that the puncture sealing success rate of the above tire decreases in the following cases. As shown in FIGS. 7A and 7B, when a foreign object a such as a nail penetrates the noise damper b, the noise damper b is partly torn off by the foreign object a with the sealant c attached to the sponge. It tends to be the piece b1. When the foreign matter a is removed from the tire, the sponge piece b1 clogs 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. This causes a reduction in the puncture sealing success rate.
Therefore, the present invention can suppress the inability to seal a puncture hole due to sponge pieces generated when a foreign object such as a nail penetrates a noise damper, and the success rate of puncture sealing while maintaining road noise reduction performance. An object of the present invention is 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,
A pneumatic tire in which a sound damping body made of a sponge material is adhered to the inner peripheral surface of the sealant layer,
The damping body has an area S1 of a radially outer surface adhered to the sealant layer, which is smaller than an area S2 of a radially inner surface of the damping body.

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

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

In the pneumatic tire according to the present invention, it is preferable that the axial width W1 of the radial outer surface of the noise damper is 50% or less of the 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, according to the present invention, in the noise damper adhered to the inner peripheral surface of the sealant layer, the area S1 of the radially outer surface of the noise damper is smaller than the area S2 of the radially inner surface.

Therefore, it is difficult for the nail to penetrate the noise damper outside and around the radially outer surface of the noise damper. As a result, when the nail penetrates the noise damper, it is possible to prevent a part of the noise damper from being torn off and turned into sponge pieces. As a result, when the nail is pulled out, it is possible to prevent the sponge piece from entering the puncture hole and making it impossible to seal the puncture hole. That is, the puncture sealing success rate can be improved while maintaining the road noise reduction performance of the sound damper.

1 is a meridional sectional view showing an embodiment of a pneumatic tire of the present invention; FIG. 1 is a circumferential cross-sectional view of a pneumatic tire along the tire equatorial plane; FIG. It is a partial perspective view showing a sound damping body. FIG. 4 is a cross-sectional view showing an effect of a sound damping body; (A) and (B) are sectional views showing other effects of the noise damper. FIG. 3 is a circumferential cross-sectional view of a pneumatic tire showing another example of a noise damper; (A) and (B) are cross-sectional views for explaining the problem to be solved by the present invention .

BEST MODE FOR CARRYING OUT THE INVENTION 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 puncture-preventing sealant layer 11 disposed on the inner peripheral surface 2s of the tread portion 2, and a sealant layer 11 inside the sealant layer 11. and a sound damping body 12 adhered to the peripheral surface 11s.

In this example, the pneumatic tire 1 includes 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 radially outside the carcass 6 and inside the tread portion 2. A positioned belt layer 7 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 has ply turn-up portions 6b at both ends of a ply main body portion 6a that straddles between the bead cores 5, 5 by turning the bead cores 5 from the inner side to the outer side in the axial direction of the tire. Between the ply main body portion 6a and the ply turnup portion 6b, a bead apex rubber 8 for bead reinforcement is provided, tapering outward from the bead core 5 in the tire radial direction.

The belt layer 7 is formed of 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. Each of the belt plies 7A, 7B is 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) formed by spirally winding a band cord may be provided radially outward 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 internal pressure of the tire airtight.

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

As the rubber component, butyl-based rubbers such as butyl rubber and halogenated butyl rubber are employed. As the rubber component, the butyl rubber and the diene rubber can be mixed, but from the viewpoint of fluidity, etc., the content of the butyl rubber in 100% by mass of the rubber component is set to 90% by mass or more. is preferred.

Liquid polymers include 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, and the like. 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, more preferably 100 parts by mass or more, relative to 100 parts by mass of the rubber component. If the content is less than 50 parts by mass, the adhesiveness 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 may flow during running.

As cross-linking agents, well-known compounds can be used, but organic peroxides are preferred. By using a butyl rubber or a liquid polymer in an organic peroxide cross-linking system, adhesiveness, sealability, fluidity, and workability are improved.

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

The content of the organic peroxide (crosslinking agent) is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more with respect to 100 parts by mass of the rubber component. If the content is less than 0.5 parts by mass, the crosslink density may be low and the sealant 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 cross-linking density may increase and the sealing performance may deteriorate.

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

Crosslinking aids (vulcanization accelerators) include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamine, aldehyde-amine, aldehyde-ammonia, imidazoline, xanthate, and quinonedioxime compounds (quinoid compounds). The amount of the cross-linking aid (vulcanization accelerator) to be blended 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 amount of the inorganic filler compounded 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 oils, naphthenic process oils, paraffinic process oils, and the like. The blending 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 coating the inner peripheral surface 2s of the tread portion 2 of the pre-vulcanized tire with a sealant material prepared by adjusting and mixing the above materials. Preferably, as described in Patent Document 1, for example, a sealant material continuously extruded from a twin-screw kneading extruder is spirally adhered to the inner peripheral surface 2s of the tread portion 2 of the rotating tire. By heating the tire coated with the sealant material and vulcanizing the sealant material, a sealant layer 11 having excellent sealing properties is formed.

The formation range of the sealant layer 11 preferably includes at least a region between reference lines X in the tire radial direction passing through the tread 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, more preferably 5.0 mm or less. If the thickness is less than 1.0 mm, it becomes difficult to reliably seal the puncture hole. Conversely, even if it exceeds 10.0 mm, the effect of plugging the punctured hole does not change much, and rather the weight of the tire increases, which is a disadvantage.

A noise damper 12 made of a sponge material is adhered to the inner peripheral surface 11s of the sealant layer 11. As shown in FIG. In this example, the sound damping body 12 is adhered by the adhesive force of the sealant material.

The area S1 of the radially outer surface Fo of the sound damping body 12 is set smaller than the area S2 of the radially inner surface Fi. Note that the radially outer surface Fo is a surface where the sound damping body 12 is adhered to the sealant layer 11 . The radially inner surface Fi is the surface on which the sound damping body 12 faces the inside of the tire lumen H, and is substantially parallel to the radially outer surface Fo.

The areas S1 and S2 are defined as the areas of surfaces obtained by flattening the unevenness, if the radially outer surface Fo and the radially inner surface Fi have unevenness. That is, the areas S1 and S2 correspond to areas when it is assumed that the surface has no unevenness. The unevenness includes microscopic unevenness caused by open cells or closed cells in the sponge material, and unevenness caused by grooves, ribs, undulations, and the like.

In this specification, a “flat surface” is defined as a substantially flat surface having only minute unevenness caused by continuous cells or independent cells of the sponge material. In this example, the radially outer surface Fo and the radially inner surface Fi are formed by "flat surfaces".

As shown in FIG. 2, the noise damper 12 of this example extends continuously in the tire circumferential direction, and both ends E in the tire circumferential direction are butted against each other. As a result, the noise damper 12 is formed as an annular body continuous in the tire circumferential direction. Note that both ends E of the sound damping body 12 may be separated from each other. In this case, the distance between the two 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 material obtained by foaming rubber or synthetic resin is preferably employed. Examples of rubber foams include chloroprene rubber sponge, ethylene propylene rubber sponge, nitrile rubber sponge and the like. Examples of synthetic resin foams include polyurethane sponges (eg, ether polyurethane sponges, ester polyurethane sponges, ether/ester polyurethane sponges, etc.) and polyethylene sponges (eg, polyethylene sponges, etc.). In particular, ether/ester polyurethane sponges are suitable from the viewpoint of durability and quality stability.

In such a noise damper 12, the air bubbles on the surface and inside convert the vibration energy of the air vibrating inside the tire lumen into heat energy and consume it. This may reduce cavity resonance energy, ie absorb cavity resonance sound and reduce road noise.

The sponge material preferably has a density of 10 to 60 kg/m ³ . If the density is less than 10 kg/m ³ , the sound absorbing effect inside the sponge is reduced, and if it exceeds 60 kg/m ³ , the sound is easily reflected on the sponge surface and the sound absorbing effect on the sponge surface is reduced. Both reduce the road noise reduction effect. Therefore, the lower limit of 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 this example, the noise damper 12 has the axial width W1 of the radially outer surface Fo set smaller than the axial width W2 of the radially inner surface Fi. As a result, the cross section perpendicular to the length direction of the sound damping body 12 is formed in a trapezoidal shape, particularly an isosceles trapezoidal shape, with short sides on the radial outer surface Fo side.

Since W1<W2, the sound damping body 12 is formed with an overhanging portion 12A that overhangs the outer surface Fo in the axial direction of the tire.

As shown in FIG. 4, when a nail 20 is stuck in a region Yo where the radial inner surface Fi protrudes axially outward from the radial outer surface Fo, the noise damper 12 functions as follows. That is, the noise damper 12 is deformed such that the overhanging portion 12A is flipped up by the nail 20, preventing the nail 20 from penetrating the noise damper 12. As shown in FIG. Therefore, it is possible to prevent a part of the sound damping body 12 from being torn off and becoming sponge pieces. As a result, when the nail 20 is pulled out, it is possible to prevent the sponge piece from entering the puncture hole 21 and making it impossible to seal the puncture hole 21.例文帳に追加

The difference (W2-W1) between the tire axial width W1 and the tire axial width W2 is preferably 10 to 45 mm. Conversely, if the length exceeds 45 mm, the fixation becomes unstable, and the sound damping body 12 may fall down or come off the adhesive.

The sponge material (sound damping body 12) preferably has a tensile strength of 100 kPa or more. As a result, when the overhanging portion 12A is flipped up, it is possible to prevent the projecting portion 12A from tearing off and forming sponge pieces. In addition, it is possible to prevent the nail 20 from penetrating the projecting portion 12A. The tensile strength of the sponge material conforms to Section 10 "Tensile strength and elongation" specified in JISK6400 "Flexible urethane foam test method", and was measured on a No. 1 dumbbell-shaped test piece. value.

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

Therefore, in order to reduce the chance of the nail 20 penetrating through the noise damper 12, as shown in FIG. Preferably, it is reduced to 50% or less of W0. By setting the width W1 to be small in this manner, the nail 20 is less likely to penetrate the sound damping body 12 in the region Yi axially inner than the region Yo, thereby increasing the puncture sealing success rate. can be raised further. Moreover, it helps to suppress the increase in the mass of the noise damper 12 and improve the rolling resistance performance.

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

The nails (foreign matter) that could be confirmed in the market research are 15 mm in average and 30 mm in maximum length. Considering the thickness of the tread portion 2, if the thickness T of the noise damper 12 is 20 mm or more, even if the nail 20 is stuck in the region Yi, it can be prevented from penetrating through the noise damper 12. can. Even if the nail 20 sticks in the area Yi, it can be prevented from penetrating the noise damper 12 . As shown in FIGS. 5A and 5B, when the nail 20 does not penetrate the noise damper 12, the nail 20 prevents part of the noise damper 12 from being torn off and turned into sponge pieces. can. As a result, when the nail 20 is pulled out, it is possible to prevent the sponge piece from entering the puncture hole 21 and making it impossible to seal the puncture hole 21.例文帳に追加

Considering the state of wear of the tread portion 2 and variations 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.

Another embodiment of the pneumatic tire 1 is shown in FIG. In this example, a plurality of noise dampers 12 are arranged side by side in the tire circumferential direction on the inner peripheral surface 11 s of the sealant layer 11 . Each noise damper 12 has a radially outer surface Fo with a tire circumferential width Wc1 smaller than a radially inner surface Fi with a tire circumferential width Wc2. Thereby, the area S1 of the radially outer surface Fo is set smaller than the area S2 of the radially inner surface Fi. The axial width W1 and the circumferential width Wc1 of the radially outer surface Fo can be set smaller than the axial width W2 and the circumferential width Wc2 of the radially inner surface Fi.

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

Pneumatic tires (tire size: 215/55R17) having the basic structure shown in FIG. performance) and road noise reduction performance were evaluated.

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

<Puncture seal success rate>
Fifty nails (diameter 5.2 mm, length 40 mm) were evenly distributed and driven into the following width regions of the tread portion of the rim-mounted trial tire filled with internal pressure (250 kPa). The width region has a width of 108 mm in the axial direction of the tire centering on the tire equator, and corresponds to the region where the noise damper of Comparative Example 1 is adhered. Then, after leaving it for 1 hour at room temperature of 25° C., the nail was pulled out, and the puncture hole was dipped in soapy water to check for air leakage. The puncture sealing success rate was calculated and evaluated from the number of puncture holes without air leakage. The higher the value, the better.

<Road noise reduction performance>
A test tire filled with internal pressure (240 kPa) is mounted on all wheels of a vehicle (2000 cc, FF car), and the road noise measurement road (rough asphalt road) is run at 60 km/h. The in-vehicle sound at the ear position (air column resonance sound in the vicinity of a narrow band of 240 Hz) was evaluated by the sensory evaluation of the driver with an index based on Comparative Example 1 being 100. The higher the value, the better.

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

Table 2 shows the composition of the sealant material used in the sealant layer. Various chemicals shown in Table 2 are as follows.
・Butyl rubber: IIR065, manufactured by JSR Corporation ・Polybutene: HV-1900, manufactured by JX Nippon 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: Nyper NS (BPO40%, DBP48%), manufactured by NOF Corporation ・Crosslinking aid : QO (quinone dioxime), manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

1 pneumatic tire 2 tread portion 2 s inner peripheral surface 11 sealant layer 11 s inner peripheral surface 12 sound damper Fo radial outer surface Fi radial inner surface

Claims (5)

It has a sealant layer for puncture prevention on the inner peripheral surface of the tread part,
A pneumatic tire in which a sound damping body made of a sponge material is adhered to the inner peripheral surface of the sealant layer,
The noise damper has an area S1 of a radially outer surface adhered to the sealant layer that is smaller than an area S2 of a radially inner surface of the noise damper,
When the surface of the radially outer surface or the radially inner surface has only minute unevenness due to open cells or closed cells, the surface when the radially outer surface or the radially inner surface is a flat surface The area S1 or the area S2 is defined as the area,
When the surface of the radially outer surface or the radially inner surface has unevenness due to grooves, ribs, undulations, etc., the area of the surface when the radially outer surface or the radially inner surface is flattened The area S1 or the area S2 is defined,
A pair of projecting portions are formed on both sides of the noise damper in the axial direction of the tire,
Each of the pair of overhanging portions includes a side surface that slopes toward the tire equator from the inner side to the outer side in the tire radial direction,
pneumatic tires. 2. The pneumatic tire according to claim 1, wherein an axial width W1 of said radially outer surface of said noise damper is smaller than an axial width W2 of said radially inner surface of said noise damper. 3. The pneumatic tire according to claim 1, wherein the radially outer surface and the radially inner surface of the noise damper are flat surfaces, and the thickness T between the radially outer surface and the radially inner surface is 20 mm or more. The pneumatic tire according to any one of claims 1 to 3, wherein the tire axial width W1 of the radially outer surface of the noise damper is 50% or less of the tire axial width W0 of the sealant layer. The pneumatic tire according to any one of claims 1 to 4, wherein the sponge material has a tensile strength of 100 kPa or more.

Images