JP2001287509A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of improving wettability while maintaining abrasion resistance. SOLUTION: Since tread rubber 12A and water repellent rubber 13 are exposed on a groove wall of a circumferential directional groove 14 and a peripheral groove 16 so as to extend in the lengthwise direction of the groove and to be alternately arranged in the direction for crossing the lengthwise direction of the groove, a regular vertical vortex can be made in water flowing in the groove, and since resistance of a flow is reduced by restraining generation of a random vortex, the wettability is improved. Since the water repellent rubber 13 is arranged only in the vicinity of the groove wall, the volume of the tread rubber 12A excellent in abrasion resistance is secured, and the abrasion resistance can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire, and more particularly to a tire having improved wet performance.

[0002]

2. Description of the Related Art A plurality of grooves are formed in a tread of a tire to obtain wet performance.

In order to improve tire performance on wet road surfaces, such as hydroplaning performance or wet braking performance, it is necessary to improve the drainage of grooves.

In order to improve drainage, it is necessary to reduce the resistance of the fluid flowing in the groove between the fluid at the wall of the groove and the wall.

As a prior art, a fine circumferential groove is provided on a groove wall to improve drainage of the groove (Japanese Patent Laid-Open No. 4-20 / 1990).
No. 1606, JP-A-7-037708), dimples are provided on the groove wall (JP-A-3-57704), and rubber having high water repellency is provided on the entire surface of the groove wall (JP-A No. 1-37704).
1-078413) and the like.

[0006]

However, as a result of various experiments and examinations of the above-mentioned proposals, there is a problem that the resistance increases due to an increase in the surface area of the groove wall if only the groove wall is provided with irregularities.

Further, in the method of providing the water-repellent rubber on the entire surface of the groove wall, a large amount of expensive and special water-repellent rubber is used near the groove wall, so that the cost is increased and the wear resistance is lowered. . The present invention has been made in consideration of the above-described circumstances, and has as its object to provide a tire that can surely reduce fluid resistance in a groove while suppressing a decrease in wear resistance and improve wet performance.

[0008]

Means for Solving the Problems If only the groove walls are provided with irregularities, the surface area of the groove walls increases, so that the resistance also increases.

As a result of repeated experiments and studies by the inventor, random flow is generated in the groove of the tread due to turbulence, and the vortex generates resistance to the flow, hindering improvement in hydroplaning performance. It has been found.

In order to arrange the random flow, the inventor paid attention to the affinity of water on the groove surface and conducted various experimental studies. As a result, it was found that a stripe composed of a high water-repellent portion and a low water-repellent portion was formed. It has been found that when provided on a wall, a vertical vortex is generated in the groove, and the resistance of water can be reduced.

Further, it has been found that when water in the groove is separated from the groove wall, the resistance increases and the wet performance is reduced. Therefore, as a result of further experimental studies, it has been found that a vortex generating means for generating a turbulent flow is provided upstream of the separation point, and separation can be suppressed by applying energy to the turbulent flow. In particular, in the case of a block pattern, it has been found that it is effective to provide many minute depressions and projections near the corners of the block.

In order to improve the hydroplaning performance at the time of a new article, a large number of minute depressions and projections are provided on the groove wall near the tire surface, that is, on the groove wall near the tread irrespective of the straight or blob pattern. It has been found that it is effective to suppress the peeling occurring on the groove wall near the tread surface.

The invention according to claim 1 is a tire having a groove in a tread, wherein a groove wall of the groove has a tread rubber serving as a main body of the tread, and extends along a longitudinal direction of the groove. Along with the water-repellent rubber having a higher water repellency than the tread rubber or a hydrophilic rubber having a lower water repellency than the tread rubber, extends along the longitudinal direction of the groove and alternately intersects with the longitudinal direction of the groove. The ratio of the volume of the water-repellent rubber or the hydrophilic rubber to 10% or less with respect to the entire rubber portion that is exposed so as to be arranged and that is located radially outside the bottom of the groove of the tread in the tire. It is characterized by being set.

Next, the operation of the tire according to the first aspect will be described.

In the tire according to the first aspect, a tread rubber serving as a main component of the tread and a water-repellent rubber or tread extending along the longitudinal direction of the groove and having higher water repellency than the tread rubber are provided on the groove wall of the groove. Since the hydrophilic rubber having lower water repellency than the rubber is exposed so as to extend along the longitudinal direction of the groove and to be alternately arranged in a direction intersecting with the longitudinal direction of the groove, the fluid flowing through the groove (water ) Can create a regular vertical vortex (vortex whose vortex axis is in the direction of flow)
The generation of random vortices can be suppressed, and the flow resistance can be reduced.

Further, the ratio of the volume of the water-repellent rubber or the hydrophilic rubber to the entire rubber portion located radially outside the bottom of the groove of the tread is suppressed to 10% or less.
The volume of the tread rubber excellent in abrasion resistance can be secured, and the abrasion resistance of the tread can be maintained.

Since the water-repellent rubber or hydrophilic rubber is inferior in wear resistance to ordinary tread rubber, when the volume ratio of the water-repellent rubber or hydrophilic rubber exceeds 10%, the wear resistance decreases.

Therefore, the water-repellent rubber or the hydrophilic rubber is
Preferably, it is provided only near the groove of the tread.

According to a second aspect of the present invention, in the tire according to the first aspect, the water-repellent rubber or the hydrophilic rubber has a width of 0.5 to 2.0 mm and a pitch of 1.5 of the width.
It is characterized by up to 2.5 times.

Next, the operation of the tire according to the second aspect will be described.

In the tire according to the second aspect, the width of the water-repellent rubber or the hydrophilic rubber is set to 0.5 to 2.0 mm and the pitch is set to 1.5 to 2.5 times the width, so that a regular longitudinal vortex is formed. It can be obtained reliably.

According to a third aspect of the present invention, there is provided a tire having a groove in a tread, wherein two or more types of rubber having different water repellency extend along a longitudinal direction of the groove on a groove wall of the groove. And it is exposed so as to be alternately arranged in a direction intersecting with the longitudinal direction of the groove, and for the entire rubber portion located in the tire radial direction outside the bottom of the groove of the tread, the water repellent It is characterized in that the ratio of the total volume of two or more different rubbers is set to 10% or less.

Next, the operation of the tire according to the third aspect will be described.

In the tire according to the third aspect, two or more types of rubber having different water repellency extend along the longitudinal direction of the groove and are alternately arranged on the groove wall of the groove in a direction intersecting with the longitudinal direction of the groove. Exposed so that the fluid (water) flowing in the groove can form a regular vertical vortex (vortex whose vortex axis is in the direction of the flow), suppressing the generation of random vortices , The flow resistance can be reduced.

Further, the ratio of the total volume of two or more types of rubber having different water repellency to 10% or less of the total rubber portion located radially outside the tire from the bottom of the groove of the tread is suppressed. The volume of the tread rubber excellent in abrasion resistance can be secured, and the abrasion resistance of the tread can be maintained.

Therefore, the water-repellent rubber or the hydrophilic rubber is
Preferably, it is provided only near the groove of the tread.

According to a fourth aspect of the present invention, there is provided the tire according to the third aspect, wherein, of the two or more rubbers having different water repellencies, either the rubber having the highest water repellency or the rubber having the lowest water repellency is used. One is characterized in that the width is 0.5 to 2.0 mm and the pitch is 1.5 to 2.5 times the width.

Next, the operation of the tire according to the fourth aspect will be described.

In the tire according to the fourth aspect, either the rubber having the highest water repellency or the rubber having the lowest water repellency has a width of 0.5 to 2.0 mm and a pitch of 1.5 to 2 mm. .5
By making it twice, regular vertical vortices can be reliably obtained.

According to a fifth aspect of the present invention, there is provided a tire having a groove in a tread, wherein a groove wall of the groove has a high water-repellent rubber having high water repellency and a water-repellent rubber which is more water-repellent than the high water-repellent rubber. Low and low water-repellent rubber are exposed so as to extend along the longitudinal direction of the groove and to be alternately arranged in a direction intersecting with the longitudinal direction of the groove, and are lower than the bottom of the groove of the tread. For all rubber parts located outside the tire radial direction,
A total volume ratio of the high water repellency rubber and the low water repellency rubber is set to 10% or less.

Next, the operation of the tire according to claim 5 will be described.

In the tire according to the fifth aspect, a high water-repellent rubber having high water repellency and a low water-repellent rubber having lower water repellency than the high water repellent rubber are provided on the groove wall of the groove in the longitudinal direction of the groove. And the fluid (water) flowing in the groove has a regular longitudinal vortex (the axis of the vortex coincides with the direction of flow) because it is exposed so as to be alternately arranged in a direction intersecting with the longitudinal direction of the groove. Vortices) can be generated, suppressing the generation of random vortices and reducing flow resistance.

Further, the ratio of the total volume of the high water-repellent rubber and the low water-repellent rubber to the entire rubber portion located radially outward of the bottom of the groove of the tread is suppressed to 10% or less. In addition, the volume of the tread rubber excellent in abrasion resistance can be secured, and the abrasion resistance of the tread can be maintained.

Therefore, it is preferable that the high water-repellent rubber and the low water-repellent rubber are provided only near the groove of the tread.

According to a sixth aspect of the present invention, in the tire according to the fifth aspect, one of the high water-repellent rubber and the low water-repellent rubber has a width of 0.5 to 2.0 mm and a pitch of 0.5 to 2.0 mm. It is characterized by being 1.5 to 2.5 times the width.

Next, the operation of the tire according to claim 6 will be described.

In the tire according to the sixth aspect, either one of the high water repellent rubber and the low water repellent rubber has a width of 0.5 to 2.0 m.
By setting the m and the pitch to 1.5 to 2.5 times the width, a regular vertical vortex can be reliably obtained.

According to a seventh aspect of the present invention, there is provided a tire having a groove in a tread, wherein the groove wall of the groove has a higher water repellency than a tread rubber which is a main component of the tread, and a longitudinal direction of the groove. A plurality of high water-repellent regions extending along a direction are arranged at intervals in a direction intersecting the longitudinal direction of the groove, and the high water-repellent region is formed by applying a water-repellent material to the tread rubber. It is characterized by comprising.

Next, the operation of the tire according to claim 7 will be described.

In the tire according to the seventh aspect, the groove wall of the groove has a higher water repellency than the tread rubber forming the main part of the tread, and a high water repellent region extending along the longitudinal direction of the groove has a longitudinal direction. Are arranged at intervals in the direction that intersects with the fluid, so that a regular vertical vortex (vortex whose vortex axis coincides with the direction of flow) can be created in the fluid (water) flowing in the groove, Vortices can be suppressed and flow resistance can be reduced.

The high water-repellent region is formed by applying a water-repellent material to the tread rubber, so that a volume of the tread rubber excellent in abrasion resistance is secured, and the abrasion resistance of the tread is improved. Can be maintained.

The coating thickness of the material having water repellency is not particularly limited, but may be any thickness as long as the material does not disappear due to friction of stone, sand, soil, or the like entering the groove.

According to an eighth aspect of the present invention, in the tire according to the seventh aspect, the high water-repellent region has a width of 0.5 to 2.
0 mm, and the pitch is 1.5 to 2.5 times the width.

Next, the operation of the tire according to claim 8 will be described.

In the tire according to the eighth aspect, the high water-repellent region has a width of 0.5 to 2.0 mm and a pitch of 1.5 to 2.5 mm.
By setting it to five times, a regular vertical vortex can be reliably obtained.

According to a ninth aspect of the present invention, there is provided a tire having a groove in a tread, wherein a groove wall of the groove has a higher hydrophilicity than a tread rubber which is a main component of the tread, and a longitudinal direction of the groove. A plurality of high hydrophilic regions extending along the direction are arranged at intervals in a direction intersecting with the longitudinal direction of the groove, and the high hydrophilic region applies a material having hydrophilicity to the tread rubber. It is characterized by comprising.

Next, the operation of the tire according to the ninth aspect will be described.

[0048] In the tire according to the ninth aspect, the groove wall of the groove has a higher hydrophilicity than the tread rubber that forms the main component of the tread, and a highly hydrophilic region extending along the longitudinal direction of the groove has a longitudinal direction. Are arranged at intervals in the direction that intersects with the fluid, so that a regular vertical vortex (vortex whose vortex axis coincides with the direction of flow) can be created in the fluid (water) flowing in the groove, Vortices can be suppressed and flow resistance can be reduced.

Further, since the highly hydrophilic region is formed by applying a material having hydrophilicity to the tread rubber, a volume of the tread rubber excellent in abrasion resistance is secured, and the abrasion resistance of the tread is improved. Can be maintained.

The coating thickness of the material having hydrophilicity is not particularly limited, but it is sufficient that the coating thickness does not disappear due to the friction of stones, sand, soil or the like entering the grooves.

According to a tenth aspect of the present invention, in the tire according to the ninth aspect, the high hydrophilic region has a width of 0.5 to 0.5.
The width is 2.0 mm and the pitch is 1.5 to 2.5 times the width.

Next, the operation of the tire according to the tenth aspect will be described.

In the tire according to the tenth aspect, the width of the highly hydrophilic region is 0.5 to 2.0 mm, and the pitch is 1.5 to 2.0 mm.
By setting it to 2.5 times, a regular vertical vortex can be reliably obtained.

According to an eleventh aspect of the present invention, in the tire according to any one of the first to tenth aspects, a plurality of small grooves extending along a longitudinal direction of the groove are provided on a groove wall of the groove. The groove depth of the small groove is set in the range of 0.01 to 0.3 mm, and the pitch of the small groove is set in the range of 0.01 to 0.3 mm.

Next, the operation of the tire according to the eleventh aspect will be described.

In the tire according to the eleventh aspect, a plurality of small grooves extending along the longitudinal direction of the groove are provided on the groove wall of the groove, and the groove depth of the small groove is in the range of 0.01 to 0.3 mm. Since the pitch is set in the range of 0.01 to 0.3 mm, the resistance of water flowing in the groove can be further reduced, and the wet performance can be further improved.

According to a twelfth aspect of the present invention, in the tire according to any one of the first to eleventh aspects, the tire has a plurality of intersecting grooves, and a groove wall near a junction of the grooves. In addition, a turbulence generation region is provided in which a minute turbulence is generated in the fluid flowing near the groove wall to suppress separation of the fluid flowing in the groove.

Next, the operation of the tire according to claim 12 will be described.

In the tire according to the twelfth aspect, the turbulent flow generation area provided on the groove wall near the confluence of the grooves causes minute turbulence in the fluid flowing near the groove wall, and flows in the groove. Suppress fluid separation. Thereby, the wet performance of the tire can be further improved.

According to a thirteenth aspect of the present invention, in the tire according to any one of the first to twelfth aspects, the fluid flowing near the groove wall near the opening on the tread side of the groove is formed. It is characterized in that a turbulent flow generation region is provided which generates a minute turbulent flow and suppresses separation of a fluid flowing in the groove.

Next, the operation of the tire according to claim 13 will be described.

When running on a wet road surface and the water on the road surface flows into the groove through the tread side opening, the fluid flowing near the groove wall is formed by the turbulent flow generation area provided on the groove wall near the opening. Since minute turbulence occurs, water on the road surface flows into the groove with a small resistance.

Thus, the wet performance when new is further improved.

According to a fourteenth aspect of the present invention, in the tire according to the twelfth or thirteenth aspect, the turbulence generation region has a diameter within a range of 0.01 to 0.3 mm and a height of 0.1 to 0.3 mm. 0
It is characterized by having a large number of point-like projections within a range of 1 to 0.3 mm.

Next, the operation of the tire according to claim 14 will be described.

The tire according to claim 14 has a diameter of 0.1.
Many point-like projections in the range of 0.01 to 0.3 mm and a height in the range of 0.01 to 0.3 mm cause a large number of minute turbulence near the groove wall to suppress separation of the water flow. .

According to a fifteenth aspect of the present invention, in the tire according to the twelfth or thirteenth aspect, the turbulence generation region has a diameter within a range of 0.01 to 0.3 mm and a depth of 0.1 to 0.3 mm. 0
Having a large number of depressions in the range of 1 to 0.3 mm,
It is characterized by:

Next, the operation of the tire according to claim 15 will be described.

The tire according to claim 15 has a diameter of 0.1 mm.
A large number of depressions in the range of 01 to 0.3 mm and a depth in the range of 0.01 to 0.3 mm generate a large number of minute turbulent flows near the groove wall, and suppress separation of the water flow.

[0070]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Next, a first embodiment of the tire of the present invention will be described with reference to FIGS.

As shown in FIG. 2, the tread 12 of the tire 10 has a tire circumferential direction (the direction of arrow A and the direction of arrow B).
A plurality of blocks 18 are formed by a plurality of circumferential grooves 14 extending along the horizontal direction and a plurality of lateral grooves 16 intersecting the circumferential grooves 14.

Since the internal structure of the tire 10 of the present embodiment is the same as that of a normal pneumatic tire, the description of the internal structure is omitted.

Although the tire 10 of the present embodiment is a pneumatic tire, the present invention can be applied to a tire other than a pneumatic tire (for example, a total rubber tire).

As shown in FIGS. 1 and 3, the circumferential grooves 14
On the groove side surface and groove bottom surface, and on the groove side surface and groove bottom surface of the lateral groove 16, a water-repellent rubber 13 having higher water repellency than the tread rubber 12A which is the main component of the tread 12 extends along the longitudinal direction of the groove, and It is exposed so as to be alternately arranged in a direction intersecting with the longitudinal direction.

In the groove bottom portion at the intersection of the circumferential groove 14 and the lateral groove 16, the tread rubber 12A and the water-repellent rubber 13 are formed in the longitudinal direction of the circumferential groove 14 by giving priority to the circumferential groove 14. Extends along.

As shown in FIG. 3, the water-repellent rubber 13 is provided only near the surface of the groove side surface and the groove bottom surface of the circumferential groove 14.

The water-repellent rubber 13 has a width W of 0.5 to 2.0 m.
m, and the pitch (center-to-center) P is preferably 1.5 to 2.5 times the width W.

The ratio of the volume of the water-repellent rubber 13 to the entire rubber portion (the portion above the two-dot chain line in FIG. 3) located radially outside the groove bottom of the tread 12 is set to 10% or less. ing.

Although the thickness of the water-repellent rubber 13 is not particularly limited, it is the above-mentioned volume ratio (10% or less) as long as the water-repellent rubber 13 does not disappear by the friction of road stones, sand, soil, etc. before the tire life. good.

The water-repellent rubber 13 of the present embodiment is a rubber having a higher water-repellency than the tread rubber 12A that forms the main part of the tread 12.

The water repellency can be represented by a contact angle as is well known. The contact angle (degree) is such that a water drop having a size (about 1 mm in diameter) that is hardly affected by gravity is dropped on a horizontal rubber surface, and a tangent line to the water drop surface on the rubber surface at that time contacts the water drop. This is the value measured by the contact angle meter with respect to the angle θ formed by the rubber surface on the side where the contact is made. The larger the contact angle, the higher the water repellency.

The smaller the contact angle, the lower the water repellency. In this case, it can be expressed that the hydrophilicity is higher than that of the contact angle larger. In other words, the higher the water repellency, the lower the hydrophilicity, and the lower the water repellency, the higher the hydrophilicity.

The water-repellent rubber 13 of the present embodiment is a rubber having a fluorine-based additive in the compounding component, and the tread rubber 12A constituting the main component of the tread 12 is a rubber having no fluorine-containing additive in the compounding component. The tread rubber 12A is a conventionally known rubber composition.

Here, it is advantageous that the fluorine-based additive is composed of a copolymer containing a perfluoroalkyl group, and that the fluorine-based additive is in the form of an oligomer. Contribute to increase.

The fluorine-based additive comprising a perfluoroalkyl group copolymer to be blended in the rubber composition includes a perfluoroalkyl group-containing ethylenically unsaturated monomer and an acetoacetyl group-containing ethylenically unsaturated monomer. Are suitable for use.

The amount of these fluorine-based additives was 10
It is desirable that the amount be in the range of 1 to 20 parts by weight relative to 0 parts by weight.

Here, the reason that the fluorine-based additive is required to be composed of a perfluoroalkyl group copolymer is effective when added in a small amount, and changes in mechanical properties such as curing of a rubber matrix component and deterioration of physical properties. This is because the water-repellent effect is exhibited without accompanying.

When a general fluorine-based resin is simply blended, it is difficult to achieve both water repellency and physical properties.

Further, it is suitable that the fluorine-based additive is in the form of an oligomer and has a molecular weight in the range of 7000 to 9000. The reason is that by setting the molecular weight of the additive within this range, the polymer becomes lower in polymer than the polymer of the rubber composition (generally, the molecular weight is several hundred thousand), and as a result, the degree of dispersion of the additive in the rubber composition is reduced. At the same time that the copolymerized oligomer is entangled with the polymer in the rubber, thereby strengthening the bonding force between the fluorine-based additive and the rubber composition through a strong bonding force. This is because the durability of the water repellent effect can be improved.

Further, by adding a silicon oxide, for example, silica to the above rubber composition, a strong adsorptive action of silica on a fluorine-based additive is utilized, and by further adding a silane coupling agent, silica is added. Thus, the bonding strength between the fluorine additive and the rubber composition can be further increased, and the durability of the water repellent effect can be further improved.

In this embodiment, the rubber is made water-repellent by using a fluorine-based additive. However, by using a well-known water-repellent additive other than the fluorine-based additive, the rubber is made water-repellent. You may have it. (Operation) In the tire 10 of the present embodiment, the water repellent rubber having higher water repellency than the tread rubber 12 </ b> A forming the main part of the tread 12 is provided on the groove side surface and the groove bottom surface of the circumferential groove 14 and the groove side surface and the groove bottom surface of the lateral groove 16. 13 are exposed so as to extend along the longitudinal direction of the groove and to be alternately arranged in a direction intersecting with the longitudinal direction of the groove.
5 (see FIG. 13) can be produced, and the generation of random vortices can be suppressed, and the resistance to water flow can be reduced.

Thus, the wet performance can be improved.

Also, the volume ratio of the water-repellent rubber 13 is suppressed to 10% or less with respect to the entire rubber portion located radially outward of the groove bottom of the tread 12, so that the tread having excellent wear resistance. The volume of the rubber 12A can be secured, and the wear resistance of the tread 12 can be maintained.

The difference between the water repellency of the tread rubber 12A and the water repellency of the water repellent rubber 13, here the difference in the contact angle, is at least 5 ° or more, preferably 10 ° or more. By increasing the difference in water repellency, a strong vertical vortex can be regularly formed in the water flowing in the groove.

If the contact angle is less than 5 °, it may not be possible to form a regular vertical vortex in the water flowing in the groove. [Second Embodiment] Next, a tire according to a second embodiment of the present invention will be described.

The tire 20 of the present embodiment is the same as the first tire described above.
The water-repellent rubber 13 of the tire 10 of the embodiment is replaced with a hydrophilic rubber.

Here, the hydrophilic rubber of the present embodiment refers to a rubber having lower water repellency and being more easily wetted by water than the tread rubber 12A which forms the main component of the tread 12.

The hydrophilic rubber of this embodiment is a rubber having a surfactant as a compounding component.

As the surfactant, as a nonionic surfactant, for example, an electrostripper TS-2
B, Electrostripper-EA, Electromaster A-1015 (all manufactured by Kao) and the like can be used.

The pneumatic tire 20 of the present embodiment also has the first
In the same manner as in the embodiment, a regular vertical vortex can be formed in the water flowing in the groove, the generation of random vortices can be suppressed, and the resistance of the water flow can be reduced. Thereby, wet performance can be improved.

Further, the ratio of the volume of the hydrophilic rubber to the entire rubber portion located radially outward of the groove bottom of the tread 12 in the tire is suppressed to 10% or less, so that the tread rubber 12A having excellent wear resistance is provided. And the abrasion resistance of the tread 12 can be maintained.

The width and pitch of the hydrophilic rubber are defined as follows.
It is the same as the water-repellent rubber 13.

The difference between the hydrophilic property of the tread rubber 12A and the hydrophilic property of the hydrophilic rubber, that is, the difference in contact angle here is at least 5 ° or more, preferably 10 ° or more, as in the case of water repellency. By increasing the difference in hydrophilicity, it is possible to form regularly strong vertical vortices in the water flowing in the grooves.

If the contact angle is less than 5 °, it may not be possible to form a regular vertical vortex in the water flowing in the groove. [Third Embodiment] Next, a tire according to a third embodiment of the present invention will be described. The same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The pneumatic tire 30 of this embodiment is similar to that shown in FIG.
As shown in FIG. 5, the water-repellent rubber 13 and the hydrophilic rubber 32 extend along the groove longitudinal direction on the groove side surface and the groove bottom surface of the circumferential groove 14 and the groove side surface and the groove bottom surface of the lateral groove 16. It is exposed so as to be alternately arranged in a direction crossing the direction.

The pneumatic tire 30 of this embodiment can also form a regular vertical vortex in the water flowing in the groove, suppress the generation of random vortices, and reduce the resistance of the water flow.

Since the water-repellent rubber 13 and the hydrophilic rubber 32 have greatly different water-repellency, it is possible to form a regular and stronger vertical vortex in the water flowing in the groove than in the first and second embodiments. Resistance can be further reduced.

Thus, the wet performance can be further improved.

In addition, the ratio of the total volume of the water-repellent rubber 13 and the hydrophilic rubber 32 to the entire rubber portion located outside the groove bottom of the tread 12 in the tire radial direction is suppressed to 10% or less, whereby the resistance to tread 12 is reduced. Tread rubber 1 with excellent wear properties
It is possible to secure a volume of 2 A and maintain the wear resistance of the tread 12.

In the case of the present embodiment, the width W1 and the pitch P of either the water repellent rubber 13 or the hydrophilic rubber 32 may be specified. [Fourth Embodiment] Next, a tire according to a fourth embodiment of the present invention will be described. The same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The tire 40 of the present embodiment is a modified example of the tire 10 of the first embodiment.

As shown in FIG. 6, the constant width W2 at the intersection of the circumferential groove 14 and the lateral groove 16 of the block 18 is
In this turbulent flow area 42, a number of point-like projections 44 are provided at random as shown in FIG. Note that the turbulent flow region 42 has only a different surface shape, and the type of exposed rubber is the same as the other portions.

Here, the width W2 of the turbulent flow region 42 is preferably 1 mm or more.

The point-like projections 44 of this embodiment have a convex spherical shape (part of a sphere), a diameter d1 in the range of 0.01 to 0.3 mm, and a height h of 0.01 to 0.3 mm. Is set within the range.

The ratio of the point-like projections 44 per unit area of the turbulent flow area 42 is preferably 30% or more.

In this embodiment, the circumferential grooves 14 and the lateral grooves 16
Turbulence occurs in the water flowing near the groove side surface due to the large number of point-like projections 24 provided on the groove side surface near the confluence with the groove, so that separation of water entering the groove is suppressed, and water is reduced with a small resistance in the groove. Can flow into Therefore, the wet performance of the tire 40 can be further improved. [Fifth Embodiment] Next, a tire according to a fifth embodiment of the present invention will be described with reference to FIG. The same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The tire 50 of this embodiment is a modification of the tire 40 of the fourth embodiment. As shown in FIG. 8, in addition to the vicinity of the confluence of the circumferential groove 14 and the lateral groove 16, the tread on the side surface of the groove is used. A turbulence generation region 42 is also provided in the constant width W2 on the side. (Operation) The tire 50 travels on a wet road surface, and water on the road surface flows into the circumferential groove 14 and the lateral groove 16 through the opening on the tread side.
When the water flows into the inside, turbulence is generated in the water flowing near the groove side surface due to the large number of point-like projections 44 provided near the opening, so that separation of the entering water is suppressed, and the water on the road surface is reduced with a small resistance. It can be flowed into.

Thus, the wet performance when the tire 50 is new can be further improved. [Sixth Embodiment] Next, a tire according to a sixth embodiment of the present invention will be described with reference to FIGS. The same components as those of the above-described embodiment are denoted by the same reference numerals,
The description is omitted.

The tire 52 of this embodiment is a modification of the tire 50 of the fifth embodiment. As shown in FIG. 9, the groove side surface and the groove bottom surface of the circumferential groove 14 and the groove side surface and the groove bottom surface of the lateral groove 16 are provided. Are formed with riblets 54 respectively.

As shown in FIG. 10, the riblet 54 of the present embodiment has a small groove 56 having a triangular cross section extending along the longitudinal direction of the groove (the circumferential groove 14 or the lateral groove 16).
It is formed continuously in the horizontal direction (the width direction of the small groove 56).

The groove depth D of these small grooves 56 is 0.01 to
The pitch P is set in the range of 0.3 mm, and the pitch P is set in the range of 0.01 to 0.3 mm.

The position of the water-repellent rubber 13 (not shown) is the same as that of the tire 50 of the fifth embodiment. (Operation) In the tire 52 of the present embodiment, a small groove 56 having a groove depth D set within a range of 0.01 to 0.3 mm is formed in the circumferential groove 14 and the lateral groove 16 at a pitch P = 0.01 to 0. .3mm
, The resistance of water flowing in the groove is further reduced, and the wet performance is further improved.

If any one of the groove depth D and the pitch P of the small groove 56 is out of the above range, the effect of reducing water resistance is insufficient.

In the riblet 54 of this embodiment, the small grooves 56 each having a triangular cross section are formed continuously in the horizontal direction.
There may be some gap between the groove and the small groove 56.

Although the riblet 54 here is described as having a large number of small grooves 56 arranged, it may be one having a large number of rib-shaped projections (strips) arranged. In this case, the space between the rib-shaped protrusions corresponds to the small groove 56.

Although the cross section of the small groove 56 is triangular, other shapes such as a rectangle, a trapezoid, and a semicircle may be used as long as the effect of reducing the resistance of the water flow is obtained. [Other Embodiments] The tire 1 of the above embodiment
Each of the tires 0, 20, 30, 40, 50, and 52 was a block pattern tire, but the tread pattern is not limited to this, and a so-called rib pattern in which only the circumferential grooves are formed in the tread (see FIG. 2). (A pattern obtained by removing the horizontal groove 16 from the pattern), or a known pattern such as a directional pattern having an inclined groove, a bent groove, or the like.

For example, when manufacturing a tire having a rib pattern to which the present invention is applied, as shown in FIG. 11, a belt-shaped water-repellent rubber (uncured vulcanized) extending along the longitudinal direction (the front and back direction of the paper surface of FIG. 11). ) 13 may be used as tread rubber (unvulcanized) 12A provided on the surface. In this case, a water-repellent rubber 13 is provided on a portion facing a bone (rib for forming a circumferential groove) 62 provided on the inner surface of a mold 60 for vulcanizing the tire.
Should be provided. Tread rubber (unvulcanized) 1 in vulcanization process
When the 2A is pressed against the inner surface of the mold 60, the water-repellent rubber 13 can be provided only in the circumferential groove portion.

Incidentally, the tread rubber (unvulcanized) 12A is
It is preferable that a portion facing the bone portion 62 be dented in advance. Thereby, the rubber flow near the surface when pressed against the mold 60 is suppressed, and the water-repellent rubber 13 can be provided at a certain width and at an interval.

In the above-described embodiment, the point-like projection 24 has a convex spherical shape. However, the present invention is not limited to this, and may have another shape such as a triangular pyramid.

In Embodiments 4, 5, and 6 described above, a large number of point-like projections 24 are formed on the groove side surface to suppress the separation of the water flow, and turbulence is generated. However, the present invention is not limited to this. ,
Even if a large number of minute depressions 28 as shown in FIG. 12 are formed instead of the point-like projections 24, the same operation and effect can be obtained as in the case where many point-like projections 24 are formed.

The depression 28 shown in FIG. 12 has a concave spherical shape, a diameter d2 within the range of 0.01 to 0.3 mm, and a depth D1.
Is set in the range of 0.01 to 0.3 mm. The ratio of the depression 28 per unit area is preferably 30% or more. Further, the depression 28 is not limited to the concave spherical shape, and may have another shape.

In the above-described embodiment, the water-repellent rubber 13 and / or the hydrophilic rubber 32 are provided integrally near the surface of the tread rubber 12A. However, a high water-repellent area (low hydrophilic area) is formed on the groove surface. The water-repellent material and / or the hydrophilic material may be applied to the surface of the tread rubber 12A as long as the low-water-repellent regions (highly hydrophilic regions) are provided alternately. In this case, there is no need to use special rubber,
The wet performance can be easily improved simply by applying a water-repellent material and / or a hydrophilic material in a stripe shape to a conventionally manufactured tire (in some cases, a raw tire before vulcanization may be used).

As the water repellent material applicable to rubber, 4
Fluorinated ethylene resin, phenyltriethoxysilane, dimethyl silicone oil and the like can be used.

Examples of the hydrophilic material that can be applied to the rubber include Electrostripper TS-2B, Electrostripper-EA, and Electromaster A-1015 (all manufactured by Kao). (Test Example 1) In order to confirm the effect of the present invention, six types of test tires having a tire size of PSR185 / 70R17 were prepared, and hydroplaning performance and wear resistance were compared.

Hereinafter, the test tire will be described.

Each of the tread patterns of the test tires is a rib pattern in which four circumferential grooves (depth 8 mm, width 10 mm) are formed in the tread.

The compositions of the water-repellent rubber and the tread rubber used in the test tire are as shown in Table 1 below.

The contact angle of the water-repellent rubber is the difference from the contact angle of the tread rubber.

[0139]

[Table 1]

Tire of Test Example a (conventional example): A tire having smooth groove walls and a tread made of normal rubber. -Tire of Test Example b: A tire in which a water-repellent rubber having a width of 0.5 mm was exposed at a pitch of 1 mm on the groove wall. The ratio of the volume of the water-repellent rubber to the entire rubber portion located radially outward of the groove bottom from the tire bottom is 8%. Tire of Test Example c: A tire in which hydrophilic rubber having a width of 0.5 mm was exposed at a pitch of 1 mm on the groove wall. The ratio of the volume of the hydrophilic rubber to the entire rubber portion located radially outward of the groove bottom from the groove bottom is 8%. -Tire of Test Example d: A tire in which a water-repellent rubber having a width of 0.5 mm is exposed on a groove wall at a pitch of 1 mm, and a hydrophilic rubber is exposed between the water-repellent rubbers. The ratio of the total volume of the water-repellent rubber and the hydrophilic rubber to the entire rubber portion located radially outward of the groove bottom from the tire bottom is 10%. -Tire of Test Example e (conventional example): The entire tread has a laminated structure of normal rubber and water-repellent rubber. 1.5mm width on the groove wall
The tire whose water-repellent rubber was exposed at a pitch of 3 mm. The ratio of the volume of the water-repellent rubber to the entire rubber portion located radially outward of the groove bottom from the groove bottom is 15%. -Tire of test example f (conventional example): A tire whose entire groove wall is made of a water-repellent rubber. The ratio of the volume of the water-repellent rubber to the entire rubber portion located radially outward of the groove bottom from the groove bottom is 5%.

Hydroplaning test method: A test tire was placed on a 5J-14 rim with an internal pressure of 2.0 kgf / cm ² (2MP
The vehicle was assembled in a), mounted on a passenger car, and entered into a pool with a depth of 10 mm at a different speed, and a test driver evaluated the occurrence rate of the heidle planing.

The evaluation is as shown in Table 2 below. In the evaluation, the hydroplaning generation speed was determined, and expressed as an index with the tire of Test Example a (conventional example) being 100. The higher the value, the higher the hydroplaning generation speed and the better the wet performance.

Abrasion resistance test method: A test tire was mounted on a passenger car, a wear test was performed on a test course of 5000 km, and the reciprocal of the amount of wear was determined.
It was represented by an index.

The evaluation is as shown in Table 2 below. The larger the value, the better the wear resistance.

[0145]

[Table 2]

As a result of the test, it can be seen that the test examples b, c, and d to which the present invention is applied have better hydroplaning properties than the test example e, which is a conventional example, and the wear resistance is not deteriorated. In Test Example f, the wear resistance of Test Example a,
It can be seen that the degree of improvement of the hydroplaning property is low although it is equivalent to b, c and d. (Test Example 2) In order to confirm the effects of the present invention, six types of test tires having a tire size of PSR235 / 45R17 were prepared, and the hydroplaning performance and the wear resistance were compared.

Hereinafter, the test tire will be described.

Each of the following test tires is a block pattern having four circumferential grooves as shown in FIG. 2, and the size of the block 18 is 35 mm in the tire circumferential direction and 35 mm in the tire width direction. Is 35 mm and the height (groove depth) is 8 mm. The width of the circumferential groove is 10 mm, and the width of the lateral groove is 8 m.
m. The compositions of the water-repellent rubber and the tread rubber used in the test tire are as shown in Table 1. -Tire of Test Example a: A tire having smooth groove walls and a tread made of normal rubber. -Tire of Test Example b: A tire in which a water-repellent rubber having a width of 1 mm was exposed on a groove wall at a pitch of 2.5 mm. The volume ratio of the water-repellent rubber is 7% with respect to the entire rubber portion located radially outward of the groove bottom from the tire. -Tire of Test Example c: A tire in which 1.5 mm wide water-repellent rubber is exposed at a pitch of 1.5 mm on the groove wall, and hydrophilic rubber is exposed between the water-repellent rubbers. The ratio of the total volume of the water-repellent rubber and the hydrophilic rubber to the entire rubber portion located radially outward of the groove bottom from the tire bottom is 7%. -Tire of test example d: A recess having a diameter of 0.4 mm and a depth of 0.08 mm is randomly arranged at a density of 30% near the groove confluence of the block of the tire of Example 1. -Tire of Test Example e: Protrusions having a diameter of 1.2 mm and a depth of 0.1 mm are randomly arranged at a density of 45% near the groove confluence of the block of the tire of Example 1. -Tire of Test Example f: The entire tread has a laminated structure of normal rubber and water-repellent rubber. A tire in which a water-repellent rubber having a width of 2 mm is exposed on a groove wall at a pitch of 43 mm. The ratio of the volume of the water-repellent rubber to the entire rubber portion located radially outside the groove bottom from the groove bottom is 15%. -Tire of Test Example g: A tire whose entire groove wall is made of a water-repellent rubber. The ratio of the volume of the water-repellent rubber to the entire rubber portion located radially outward of the groove bottom from the tire bottom is 8%. Hydroplaning test method: Test tire is 8JJ-
Attach to a 17 car rim with an internal pressure of 2.2kgf / cm ² (2.2MPa), attach it to a passenger car, and enter a pool with a radius of 130m and a depth of 10mm at a depth of 10m at a different speed. The planing generation speed was evaluated.

The evaluation is as shown in Table 3 below. In the evaluation, the occurrence rate of hydroplaning was determined, and Test Example a
The index was set as an index with the tire of (conventional example) being 100. The higher the value, the higher the hydroplaning generation speed and the better the wet performance.

Abrasion resistance test method: A test tire was mounted on a passenger car, and a wear test was performed on a general road including an expressway to travel 20,000 km, and the reciprocal of the amount of wear was determined. It was represented by an index.

The evaluation is as shown in Table 3 below. The larger the value, the better the wear resistance.

[0152]

[Table 3]

As a result of the test, the test examples b, c, d, and e to which the present invention was applied were better in hydroplaning properties and did not deteriorate in abrasion resistance as compared with the conventional test example f. I understand. Test examples d and e (with turbulence generation area)
Indicates that the hydroplaning property is further improved. In Test Example g, the wear resistance of Test Examples a, b, and
It can be seen that the degree of improvement in hydroplaning properties is low although it is equivalent to c, d, and e. (Test Example 3) In order to confirm the effect of the present invention, seven types of test tires having a tire size of TBR245 / 70R22.5 were prepared, and the wet brake performance was compared.

Hereinafter, the test tire will be described.

The following test tires have the same block pattern as in Test Example 2. The size of the block 18 is 35 mm in the tire circumferential direction and 35 m in the tire width direction.
m, height (groove depth) is 152 mm. The compositions of the water-repellent rubber and the tread rubber used in the test tire are as shown in Table 1. -Tire of Test Example a: A tire having smooth groove walls and a tread made of normal rubber. -Tire of Test Example b: A tire in which a water-repellent rubber having a width of 0.5 mm is exposed at a pitch of 1 mm. -Tire of Test Example c: Water-repellent rubber having a width of 1 mm has a pitch of 1.
Tire exposed at 5mm. -Tire of Test Example d: Water-repellent rubber having a width of 1 mm has a pitch of 2.
Tire exposed at 5mm. -Tire of Test Example e: Water-repellent rubber having a width of 1 mm has a pitch of 3.
Tire exposed at 5mm. -Tire of test example f: a water-repellent rubber having a width of 2 mm and a pitch of 4 m
m exposed tire.・ Tire of Test Example g: Water-repellent rubber having a width of 3 mm and a pitch of 6 m
m exposed tire. Wet brake test method: Assemble the test tire on a 7.50 rim at an internal pressure of 7.0 kgf / cm ² (7.0 MPa).
Attached to a truck and put into a pool with a depth of 10mm, speed 100km
/ h approached and the test driver evaluated the brake stopping distance.

The evaluation is as shown in Table 4 below. In the evaluation, the reciprocal of the brake stopping distance was determined, and the evaluation was represented by an index with Test Example a (the conventional tire) being 100. The larger the value, the better the wet brake performance.

[0157]

[Table 4]

From Test Examples b, c and d, it was found that if the distance between the water-repellent rubbers was too large, the flow was disturbed and the effect was reversed.

Further, according to Test Examples b, d and g, if the width of the water-repellent rubber is too large, a regular vertical vortex cannot be formed.
It turned out to be the opposite effect.

[0160]

As described above, the tires according to the first to thirteenth aspects have the above-described structure, and thus have an excellent effect that the wet performance can be improved while suppressing the decrease in wear resistance.

Since the tire according to the second, fourth, sixth, eighth and tenth aspects has the above-described structure, it is possible to surely generate a vertical vortex in the groove and to surely improve the wet performance. , Which is an excellent effect.

Since the tire according to the eleventh aspect is configured as described above, the tire has an excellent effect that the separation of the fluid flowing in the groove is suppressed and the wet performance is further improved.

According to the twelfth aspect of the present invention, there is provided an excellent effect that the water on the road surface flows into the groove with a small resistance and the wet performance when new is further improved.

Since the tire according to the thirteenth aspect has the above-described structure, an excellent effect that a large number of point-like projections generate a large number of minute turbulent flows in the vicinity of a groove wall to suppress separation of a water flow. Having.

Since the tire according to the fourteenth aspect has the above-described structure, the tire has an excellent effect that a large number of depressions cause a large number of minute turbulent flows near the groove wall to suppress separation of the water flow. .

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a tread of a tire according to a first embodiment.

FIG. 2 is a plan view of a tread.

FIG. 3 is a cross-sectional view of the block along the tire axial direction.

FIG. 4 is an enlarged perspective view of a tread of a tire according to a third embodiment.

FIG. 5 is a cross-sectional view of the block shown in FIG. 4 along the tire axial direction.

FIG. 6 is an enlarged perspective view of a tread of a tire according to a fourth embodiment.

FIG. 7 is an enlarged perspective view of a point projection.

FIG. 8 is an enlarged perspective view of a tread of a tire according to a fifth embodiment.

FIG. 9 is an enlarged perspective view of a tread of a tire according to a sixth embodiment.

FIG. 10 is an enlarged perspective view of a riblet.

FIG. 11 is a cross-sectional view showing a part of a raw tire and a mold.

FIG. 12 is an enlarged perspective view of a depression.

FIG. 13 is an explanatory diagram showing a vertical vortex.

[Explanation of symbols]

 Reference Signs List 10 tire 12 tread 12A tread rubber 13 water-repellent rubber (highly water-repellent region) 14 circumferential groove 16 lateral groove 20 tire 30 tire 32 hydrophilic rubber (highly hydrophilic region) 40 tire 42 turbulence generation region 44 point-like projection 46 depression 50 Tire 52 Tire 56 Small groove

Claims (15)

[Claims] 1. A tire provided with a groove in a tread, wherein a groove wall of the groove has a tread rubber serving as a main body of the tread, and extends along the longitudinal direction of the groove and is more repellent than the tread rubber. Water-repellent rubber having a high water repellency or hydrophilic rubber having a low water repellency than the tread rubber is exposed so as to extend along the longitudinal direction of the groove and to be alternately arranged in a direction intersecting with the longitudinal direction of the groove. Wherein the proportion of the volume of the water-repellent rubber or the hydrophilic rubber is set to 10% or less with respect to the entire rubber portion located radially outward of the bottom of the groove in the tread. And tires. 2. The water-repellent rubber or the hydrophilic rubber has a width of 0.5 to 2.0 mm and a pitch of 1.5 to 2.5 times the width. Tires. 3. A tire provided with a groove in a tread, wherein two or more types of rubber having different water repellency extend along a longitudinal direction of the groove on a groove wall of the groove, and the tire has a longitudinal direction. The rubber is exposed so as to be alternately arranged in a crossing direction, and has different water repellency with respect to the entire rubber portion located radially outside the tire in the tire than the bottom of the groove of the tread.
A tire characterized in that the ratio of the total volume of rubber of at least one kind is set to 10% or less. 4. Among the two or more rubbers having different water repellency, one of the rubber having the highest water repellency and the rubber having the lowest water repellency has a width of 0.5 to 2.0 mm and a pitch of the rubber having the above-mentioned pitch. 4. The method according to claim 3, wherein the width is 1.5 to 2.5 times the width.
The tire described in the above. 5. A tire having a groove on a tread, wherein a groove wall of the groove has a high water-repellent rubber having high water repellency and a low water-repellent rubber having a lower water repellency than the high water repellent rubber. Are extended so as to extend along the longitudinal direction of the groove and are arranged so as to be alternately arranged in a direction intersecting with the longitudinal direction of the groove, and are located radially outside the bottom of the groove of the tread in the tire radial direction. A tire characterized in that a total volume ratio of the high water-repellent rubber and the low water-repellent rubber to the entire rubber portion is set to 10% or less. 6. The high water-repellent rubber or the low water-repellent rubber has a width of 0.5 to 2.0 mm and a pitch of 1.5 to 2.5 times the width. The tire according to claim 5, wherein 7. A tire provided with a groove in a tread, wherein the groove wall of the groove has a higher water repellency than a tread rubber forming a main component of the tread, and has a high repellency extending along a longitudinal direction of the groove. A plurality of water-based regions are arranged at intervals in a direction intersecting with the longitudinal direction of the groove, and the high water-repellent region is configured by applying a water-repellent material to the tread rubber. Features tires. 8. The high water-repellent region has a width of 0.5 to 2.0 m.
The tire according to claim 7, wherein m and the pitch are 1.5 to 2.5 times the width. 9. A tire having a groove in a tread, wherein the groove wall of the groove has a higher hydrophilicity than a tread rubber forming a main component of the tread, and has a high hydrophilicity extending along a longitudinal direction of the groove. A plurality of hydrophilic regions are arranged at intervals in a direction intersecting the longitudinal direction of the groove, and the highly hydrophilic region is configured by applying a material having hydrophilicity to the tread rubber. Features tires. 10. The high hydrophilic region has a width of 0.5 to 2.0 m.
The tire according to claim 9, wherein m and the pitch are 1.5 to 2.5 times the width. 11. A plurality of small grooves extending along a longitudinal direction of the groove are provided on a groove wall of the groove, and a groove depth of the small groove is set to 0.1.
The pitch of the small grooves is set to 0.01 within the range of 0.01 to 0.3 mm.
The tire according to any one of claims 1 to 10, wherein the tire is set within a range of 0.3 mm. 12. A groove having a plurality of intersecting grooves, wherein a minute turbulence is generated in a fluid flowing near the groove wall on a groove wall near a confluence of the grooves to separate the fluid flowing in the groove. The tire according to any one of claims 1 to 11, further comprising a turbulence generation region for suppressing the turbulence. 13. A groove wall near an opening on the tread surface side of the groove,
13. The turbulent flow generation region which suppresses separation of the fluid flowing in the groove by generating a minute turbulence in the fluid flowing near the groove wall. Tires. 14. The turbulence generation region has a diameter of 0.01 to 0.1.
14. The tire according to claim 12, wherein the tire has a large number of point-like projections in a range of 3 mm and a height in a range of 0.01 to 0.3 mm. 15. The turbulence generation region has a diameter of 0.01 to 0.1.
The tire according to claim 12 or 13, wherein the tire has a large number of depressions in a range of 3 mm and a depth in a range of 0.01 to 0.3 mm.