JP3577248B2 - Pneumatic tire - Google Patents

Description

【００３７】
テストの結果、実施例のものは、ブロックパターン、リブパターンのいずれにおいても、比較例と比べて氷上制動性能などを向上していることが確認できた。また、防滑用ゴム材のゴム硬さを上げても氷上制動は比較例と同程度維持されており、このときタイヤライフを増大しうることが確認された。
【００３８】
【発明の効果】
上述したように、トレッド面に対してほぼ垂直に配向された柱状材等が路面を効果的に引っ掻くことにより、氷雪路での摩擦係数を高めて走行性能を向上させる。またトレッド面に、タイヤ加硫成形後の切削により形成されたサイピングを設けているため、加硫時にナイフブレード等を用いてサイピングを成形する場合に比して柱状材の配向が乱されることが防止され、氷雪路での走行性能向上効果がより一層期待できる。また、柱状材の上述のような配向が従来に比して向上するため、例えば防滑用ゴム材のゴム硬さを増しても従来と同程度の氷上性能を発揮することができ、この場合には防滑用ゴム材の耐摩耗性を向上でき、タイヤライフを延長させうる。なお防滑用ゴム材の硬さを限定したときには、氷路面での粘着性がますため氷路での走行性能が向上する。
【図面の簡単な説明】
【図１】本発明の実施形態であるトレッド部の部分断面図である。
【図２】トレッド面の展開図である。
【図３】（ａ）〜（ｄ）は、柱状材を例示する略図である。
【図４】（ａ）、（ｂ）は、防滑用ゴム材の製造方法を説明する略図である。
【図５】未加硫トレッドゴムを例示する断面図である。
【図６】全型の周方向に沿った部分断面図である。
【図７】単なる他の態様を単に例示するトレッド部の部分断面図である。
【図８】そのトレッド部の部分断面図である。
【図９】そのトレッド部の部分断面図である。
【符号の説明】
２ トレッド部
３ トレッド面
５ 柱状材
Ｓ サイピング
Ｇ１ 防滑用ゴム材
Ｅ トレッド端[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire that can improve running performance on ice and snow roads.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in tires (for example, studless tires) having improved running performance on ice and snowy roads, tread rubber that comes into contact with a road surface has been mixed with organic or inorganic short fibers. Such short fibers are known to be randomly oriented and, for example, substantially oriented along the thickness direction of the tread rubber. The short fibers protrude from the tread rubber like a beard and scratch the road surface (edge effect) as a main effect, and can increase the coefficient of friction on icy and snowy roads.
[0003]
In this type of tire, a block pattern having a large number of blocks formed on a tread surface is usually employed, and a large number of sipes (narrow grooves) extending substantially in the tire axial direction are formed on the block. I have.
[0004]
[Problems to be solved by the invention]
By the way, a plurality of the sipes are usually engraved per block, and the sipes are vulcanized and formed by a knife blade provided in a tire vulcanizing mold. However, by pushing the knife blade into the rubber together with the rubber flow at the time of vulcanization molding, the orientation of the short fibers and the like is irregularly disordered, and the problem that the road surface scraping effect by the short fibers and the like cannot be sufficiently obtained. is there. For this reason, in order to further improve the frictional force, for example, rubber is softened. However, in this method, the tread surface is severely worn and the tire life is significantly shortened. Further, the tread rubber containing the short fibers is generally effective on icy and snowy roads, but has a problem in that the ground contact area of the rubber is reduced on a normal dry asphalt road surface, so that the grip force is rather lowered.
[0005]
The present invention has been made devised in view of these problems, to form at least a portion of the tread surface with a non-slip rubber material blended with columnar material having a predetermined shape in rubber substrate 100 parts by weight with, as a basic to oriented at 40 to 90 ° angle to the length direction of the columnar member against the tread surface, by providing the sipes formed by cutting after the tire vulcanization, columnar by forming sipes It is an object of the present invention to provide a pneumatic tire capable of suppressing disturbance in the orientation of materials and sufficiently improving running performance on ice and snowy roads.
[0006]
[Means for Solving the Problems]
First, the present invention relates to a method of forming a columnar material made of a material having a bottom area of 10 ^{-4 to} 4.0 mm ² , a length of 0.1 to 15 mm and a material exhibiting an edge effect on a road surface in 100 parts by weight of a rubber base material. At least a part of the tread surface is formed using a rubber material for anti-slipping including up to 40 parts by weight, and the longitudinal direction of the columnar material is oriented at an angle of 40 to 90 ° with respect to the tread surface; And a siping formed by cutting after the tire vulcanization molding is provided.
[0007]
As a result, in the pneumatic tire of the present invention , the oriented columnar material or the like effectively scratches the road surface, thereby increasing the coefficient of friction on icy and snowy roads and improving running performance. In addition, siping is formed by cutting after tire vulcanization molding, so that the orientation of the columnar material can be prevented from being disordered irregularly as compared with the case where siping is formed by vulcanization, and the orientation can be effectively maintained. As a result, traveling and braking performance on ice and snow roads (hereinafter, these may be simply collectively referred to as “traveling performance”) can be effectively improved. The tread surface refers to a surface that comes into contact with a road surface under an internal pressure and load determined by a standard such as JATMA by assembling a tire with a rim.
[0008]
The columnar material is not particularly limited, but preferably includes a columnar or prismatic glass fiber in order to enhance the edge effect. The tread surface serves to generate a large driving force by forming at least one row of blocks in which blocks are arranged in the tire circumferential direction or at least one row of ribs continuous in the tire circumferential direction. Further, by setting the durometer A hardness of the rubber material for slip prevention to 40 to 60 °, the adhesive force with the road surface is increased, the contact property is further improved, and the running performance on ice and snow roads can be further improved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a partial cross-sectional view of the pneumatic tire of the present embodiment, and FIG. 2 is a developed view of a tread surface thereof. The pneumatic tire 1 of the present embodiment has a tread portion 2 and at least a part of a tread surface 3 serving as a ground contact surface of the tread portion 2 is formed of an anti-skid rubber material G1 so that it can travel on icy and snowy roads. It is configured as an improved so-called studless tire.
[0010]
In the present embodiment, the tread rubber 4 disposed on the tread portion 2 includes a base rubber 4a positioned inside between the tire radial direction tread ends E, E, a base rubber 4a disposed outside the base rubber 4a, and In this embodiment, a cap rubber 4b forming the tread surface 3 and wing rubbers 4c and 4c arranged to cover both side edges thereof are included, and the cap rubber 4b is formed from the anti-slip rubber material G1. I have. The tread rubber 4 is disposed radially outward of the belt layer 7 for loosely fastening the carcass 6 forming the skeleton of the tire.
[0011]
The anti-slip rubber material G1 is configured to include 2 to 40 parts by weight of a columnar material 5 having a predetermined shape in 100 parts by weight of a rubber base material. As the rubber substrate, for example, a diene rubber is preferable, and more specifically, natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber or the like is blended with one or more kinds. Can be used.
[0012]
The columnar member 5 is made of a material that causes the anti-skid rubber member G1 to exert an edge effect on a road surface. That is, it is first necessary that the columnar material 5 be made of a material that is kneaded and dispersed in the rubber base material and does not disappear even by vulcanization. The columnar member 5 projects in a beard shape from the surface of the rubber base material, for example, and the columnar member directly exerts an edge effect by directly scraping the road surface. In this case, the columnar member 5 is required to have a bending rigidity that is not easily broken. Further, when the columnar member 5 falls off from the rubber surface due to the progress of rubber wear or the like, the edge effect can be indirectly exerted also by the small holes remaining on the rubber surface on which the columnar member 5 is embedded. Alternatively, a water film on ice can be adsorbed using the small holes.
[0013]
Examples of the material of the columnar material 5 include, for example, organic materials such as nylon, polyester, aramid, rayon, vinylon, aromatic polyamide, cotton, cellulose resin, and crystalline polybutadiene, as well as metal fibers, whiskers, boron, Examples thereof include inorganic materials such as glass fiber, and these can be used alone or in combination of two or more. It is particularly preferable to use a nonmetallic material having a small difference in wear rate from rubber, particularly glass fiber. Further, the columnar member 5 may be subjected to a surface treatment or the like necessary for improving the adhesion to the rubber substrate.
[0014]
The compounding amount of the columnar material 5 is 2 to 40 parts by weight, more preferably 15 to 30 parts by weight, based on 100 parts by weight of the rubber base material. If the columnar material 5 is less than 2 parts by weight, the running performance on ice and snow roads cannot be sufficiently improved, and if it exceeds 40 parts by weight, crack resistance and the like of rubber tend to decrease.
[0015]
The columnar member 5 is made of glass fiber in this example, and is preferably formed in a columnar or prismatic shape, for example, as shown in FIGS. In the case of forming a prismatic shape, particularly by forming the shape into a triangular prism or a hexagonal prism, the edge of the columnar material 5 itself further increases, and thereby a higher edge effect can be expected. The bottom area A of the columnar member 5 is set to 10 ^{-4 to} 4.0 mm ² , and the length L is set to 0.1 to 15 mm. If the bottom area A of the columnar member 5 is less than 10 ^-4 mm ² or the length L of the columnar member 5 is less than 0.1 mm, the effect of scratching the road surface by the columnar member 5 itself is reduced. If the length L is larger than 0.0 mm ² or the length L is larger than 15 mm, the columnar material 5 becomes too large, the adhesiveness to rubber is reduced, and the wear resistance and crack resistance are reduced. From such a viewpoint, it is particularly desirable that the bottom area A of the columnar member 5 be 10 ^{−2 to} 4.0 mm ² and the length L be 0.3 to 15 mm. The bottom area A and the length L are both average values.
[0016]
The anti-slip rubber material G1 has a durometer A hardness of 40 to 60 °, more preferably a durometer A hardness of 40 to 60 ° when measured in an atmosphere at −10 ° C., and further preferably 45 to 60 °. It is desirable that As a result, flexibility is ensured even at low temperatures, and the contact performance with the road surface is further improved to improve running performance on icy and snowy roads, and it is also useful to maintain steering stability on dry asphalt road surfaces. The “durometer A hardness” is a rubber hardness by a durometer type A based on JIS-K6253, and is measured so as to be the thickness (the tire radial direction) of the anti-skid rubber material G1.
[0017]
Most of the columnar member 5 (for example, 90% or more) is oriented in a state where its length direction is substantially perpendicular to the tread surface 3 at an angle of 40 to 90 °. As a method for obtaining the rubber in which the columnar material 5 is oriented in this manner, for example, a calender roll r can be used as shown in FIG. As is known, an unvulcanized rubber material m in which, in addition to the rubber base material and the columnar material 5, predetermined chemicals required for vulcanization molding are blended as required, are rolled by calender rolls r and r. In this case, the length direction of the columnar material 5 is along the rolling direction X.
[0018]
Then, the rolled rubber sheet g is folded and laminated as shown in FIG. 4A to form a predetermined width, whereby the columnar material 5 is oriented in the Z direction perpendicular to the rolling direction. By using this rubber laminate such that the Z direction is the tire radial direction, a material in which the columnar material 5 is oriented substantially perpendicular to the tread surface 3 can be obtained.
[0019]
As shown in FIG. 4B, a rubber sheet g in which the columnar members 5 are oriented in the rolling direction is laminated in the thickness direction, and the laminate is cut along a plane J perpendicular to the orientation direction of the columnar members 5. To obtain the same material.
[0020]
Then, these materials are molded as necessary, as shown in FIG. 5, as a tread rubber 4 bonded to a base rubber 4a, a wing rubber 4c, and the like, and a green tire cover is molded using this. Further, the pneumatic tire 1 can be manufactured by vulcanizing the green tire cover. In the pneumatic tire 1 having such a tread surface 3, the oriented columnar member 5 or the like effectively scratches the road surface, or a small hole in the rubber surface formed by the columnar member 5 falling off the rubber. Thereby, the coefficient of friction between the road and the icy road can be increased, and the running performance can be greatly improved.
[0021]
The air-filled tire 1, the tread surface 2, and provided with sipes S formed by cutting after the tire vulcanization, which all sipes S in this embodiment is formed by cutting after the tire vulcanization Is exemplified. Generally, as shown in FIG. 6, when a siping S is formed by using a knife blade K or the like of a mold M at the time of vulcanization, the columnar material 5 existing in the flowing rubber is subjected to a rubber flow caused by the pressing of the knife blade K or the like. However, in this embodiment, since the orientation of the columnar member 5 is already fixed by the vulcanized rubber, even if the sipes S are formed by cutting, the orientation of the columnar member 5 is prevented from being disturbed. Is done. Therefore, in the pneumatic tire of the present embodiment, since the disorder of the orientation state of the columnar member 5 after vulcanization is very small, the effect of improving running performance on icy and snowy roads can be further expected. In addition, since the orientation of the columnar member 5 is improved as compared with the related art, even if the rubber hardness of the anti-skid rubber material G1 is increased, the same level of performance on ice can be exhibited. The wear resistance of the material G1 can be improved to extend the tire life.
[0022]
In the present embodiment, the tread surface 3 is formed by a block pattern including five block rows BL in which the blocks B defined by the vertical grooves 10 and the horizontal grooves 11 are arranged in the tire circumferential direction, as shown in FIG. In each block B, at least one, preferably a plurality of sipes S are formed. It should be noted that instead of the block row BL, a rib row whose contact portion is continuous in the tire circumferential direction may be used. Further, the siping S is arranged at an inclination angle θ of, for example, 0 to 60 ° with respect to the tire axial direction, and can effectively increase the edge component of the block B.
[0023]
In addition, the siping S can be formed in various shapes such as zigzag, wavy shape, or a combination thereof in addition to a linear shape as in this example. In addition to the open type in which both ends are open as in this example, only one end is opened. It can be processed in various modes such as a semi-open type and a closed type in which both ends terminate in a block. The arrangement pitch of the sipes S in the tire circumferential direction is preferably, for example, 3 to 25 mm, and the siping depth is preferably 0.3 to 1.0 times, for example, the groove depth of the vertical groove 10.
[0024]
FIG. 7 merely illustrates another embodiment. The same parts as those of the above embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, a point that a part of the tread surface 3 is formed by using the anti-skid rubber material G1 and that a length direction of the columnar material 5 is oriented at an angle of 40 to 90 ° with respect to the tread surface 3. Is the same, but the tread surface 3 has a first grounding portion 3a formed using the anti-skid rubber material G1 and a second grounding portion 3b formed of a rubber material G2 not including the columnar material 5. And
[0025]
As described above, the anti-skid rubber material G1 containing the columnar material 5 generates an effective frictional force on ice and snow roads, but has a reduced rubber contact area on ordinary dry asphalt road surfaces. Therefore, there is a problem that grip force is reduced. Therefore, in the present embodiment, the tread surface 3 includes the second ground contact portion 3b made of the rubber material G2 that does not include the columnar material 5, thereby achieving both the traveling performance on ice and the dry grip performance.
[0026]
In addition, the running performance of the tire differs depending on where on the tread surface 3 the first ground contact portion 3a is arranged. The tread surface 3 of the present embodiment has the first ground portion 3a at the center of the tread surface 3 and has second ground portions 3b extending to the tread end E on both sides thereof. In general, a large force acts on the central portion of the tread surface 3 at the time of starting, accelerating, and the like. By arranging the anti-skid rubber material G1 at this portion, the driving performance at the time of starting on a snowy road, accelerating, etc. Help improve. That is, it is suitable as a driving wheel tire to be mounted on the driving wheel. On the other hand, by providing the second ground contact portion 3b made of the rubber material G2 not including the columnar material 5 on the axial side portion of the tread surface 3, the grip force at the time of turning on a dry asphalt road surface is reduced. The driving stability is prevented from being lowered.
[0027]
At this time, the width W1 of the first ground contact portion 3a in the tire axial direction (including the width of the groove that does not touch the ground) is determined, for example, by the distance in the tire axial direction between tread ends E, which are axially outer ends of the tread surface 3. By setting the tread width TW to 0.2 to 0.6 times, more preferably 0.3 to 0.6 times, the grip force on dry asphalt road surface and driving performance on ice and snow road are improved in a good balance. sell. If the width W1 of the first contact portion 3a is less than 0.2 times the tread width TW, the contact width of the first contact portion 3a becomes small, so that it tends to be difficult to obtain a high frictional force on icy and snowy roads. On the other hand, when it exceeds 0.6 times, the contact width of the second contact portion 3b becomes small, so that the allowance for the grip force on the dry asphalt road surface becomes relatively large. Note that the first ground contact portion 3a is arranged substantially at the center of the tire equator C.
[0028]
FIG. 8 merely illustrates yet another embodiment. The tread surface 3 has the second grounding portion 3b at the center of the tread surface 3, and has the first grounding portions 3a on both sides thereof. Generally, a large lateral force acts on a side portion (a so-called shoulder portion) of the tread surface 3 at the time of turning. By arranging the anti-slip rubber material G1 on this side portion, the turning performance particularly on an icy road is improved. Help. Such a tire is suitable as a steering wheel tire suitable for being mounted on a steering wheel on which a particularly large lateral force acts during turning. On the other hand, by providing the second ground contact portion 3b made of the rubber material G2 not including the columnar material 5 at the center of the tread surface 3, the grip on the dry asphalt road surface is increased, and the drive performance and the like are reduced. Be suppressed.
[0029]
In such a rubber arrangement, the width W2 of the first ground contact portion 3a on each side in the tire axial direction is 0.1 to 0.25 times the tread width TW, more preferably 0.15 to 0. .25 times. This is because this range mainly bears a large lateral force during cornering.
[0030]
In addition, the tread surface 3 of the present example illustrates a rubber material G2 not including the columnar material 5 in a range of a small width W3 from the tread ends E and E in the tire axial direction inward. It is desirable that the width W3 be 0.05 to 0.15 times the tread width TW, more preferably 0.10 to 0.15. Since the anti-slip rubber material G1 includes the columnar material 5, the rubber material G2 which does not include the columnar material 5 around the tread edge E has a tendency to be slightly inferior in abrasion resistance, crack resistance, tear resistance and the like. By exposing the tire with a small width, rubber chipping, cracking, etc. at the tread end E can be effectively prevented, and the appearance of the tire can be improved over a long period of time. The rubber material G2 is made of a rubber material having higher wear resistance than the anti-slip rubber material G1.
[0031]
Regarding these other aspects, it is preferable to provide a siping S formed by cutting after vulcanization. As shown in FIGS. 7 and 8, the siping includes a first siping S1 including the first ground portion 3a and a second siping extending only the second ground portion 3b. And, for example, since only the second siping has nothing to do with the anti-slip rubber material G2, a mold formed by vulcanization with the knife blade K of the mold M is exemplified. This can reduce a decrease in tire productivity. Further, as shown in FIG. 9, a first ground contact portion 3a made of the rubber material G1 may be provided at both the center and the side of the tread surface 3. In this case, although the grip on a dry asphalt road surface is slightly improved, it is possible to simultaneously improve both performances such as driving and turning on an icy road.
[0032]
【Example】
A prototype of a studless tire (Example) in which the siping was vulcanized and then cut and a studless tire (comparative example) in which the siping was formed by a knife blade of a vulcanizing mold were used to provide braking performance on ice and running feeling on ice. , Feeling on snow, tire life, etc. were tested. The tire size is 195 / 65R15 in all cases. The depth of the vertical groove is about 8.5 mm, the depth of the sipe is 6 mm, and the interval between the sipe is 10 mm. Further, Comparative Example 1, Examples 1 and 2 have the same block pattern having five rows of blocks, and Comparative Examples 2, 3 and 4 have the same rib pattern having five rows of ribs. As the columnar material, glass fiber having an average bottom area of 0.3 mm ² and an average length of 0.8 mm was used, and 10 parts by weight of 100 parts by weight of the rubber base material was blended for each tire.
The contents of the test are as follows.
[0033]
<Braking performance on ice>
A 2000 cc Japanese FR car was fitted with test tires that ran on dry asphalt road surface for about 200 km, locked on an ice plate at a speed of 30 km / H, and braked until the vehicle stopped. The distance was measured. The evaluation was indexed by the following equation.
About Examples 1 and 2 (braking distance of comparative example 1) / (braking distance of each tire) × 100
Examples 3 and 4 (braking distance of comparative example 2) / (braking distance of each tire) × 100
The larger the index, the better the braking performance on ice.
[0034]
<Feeling on ice and snow>
Each of the test vehicles traveled on a test course composed of an icy road and a snowy road, and the overall driving feeling including turning, braking, acceleration, etc. was determined according to the senses of the driver according to the first and second embodiments. For Examples 3 and 4, Comparative Example 2 was evaluated as 100. The larger the value, the better.
[0035]
<Tire life>
The test vehicle traveled about 4000 km on a general road, and a travelable distance when the groove depth was reduced by 1 mm was calculated from the remaining depth of the vertical groove on the tread surface at that time. The tire with the block pattern was evaluated by an index with the travelable distance of Comparative Example 1 being 100, and the tire with the rib pattern was evaluated by the index with the travelable distance of Comparative Example 2 being 100. The larger the value, the longer the tire life.
Table 1 shows the test results.
[0036]
[Table 1]

[0037]
As a result of the test, it was confirmed that the example of the present invention has improved on-ice braking performance and the like in both the block pattern and the rib pattern as compared with the comparative example. Further, even when the rubber hardness of the anti-slip rubber material was increased, braking on ice was maintained at the same level as in the comparative example, and it was confirmed that the tire life could be increased at this time.
[0038]
【The invention's effect】
As described above, the columnar member or the like which is oriented substantially vertically by effectively scratching that the road surface with respect to preparative red surface, to improve the driving performance by increasing the friction coefficient of the icy and snowy road. In addition, since the sipes formed by cutting after tire vulcanization molding are provided on the tread surface, the orientation of the columnar material is disturbed during vulcanization compared to the case where sipes are formed using a knife blade etc. Is prevented, and the effect of improving running performance on icy and snowy roads can be further expected. In addition, since the above-described orientation of the columnar material is improved as compared with the related art, for example, even if the rubber hardness of the anti-skid rubber material is increased, the same performance on ice as the related art can be exhibited. Can improve the wear resistance of the anti-slip rubber material and extend the tire life. When the hardness of the anti-skid rubber material is limited, the traveling performance on the icy road is improved because the adhesiveness on the icy road surface is increased.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of a tread portion according to an embodiment of the present invention .
FIG. 2 is a development view of a tread surface.
FIGS. 3A to 3D are schematic diagrams illustrating columnar members.
FIGS. 4A and 4B are schematic diagrams illustrating a method for producing a rubber material for anti-slip.
FIG. 5 is a cross-sectional view illustrating an unvulcanized tread rubber.
FIG. 6 is a partial cross-sectional view along the circumferential direction of the entire die.
FIG. 7 is a partial cross-sectional view of a tread portion merely illustrating another embodiment.
FIG. 8 is a partial cross-sectional view of the tread portion.
FIG. 9 is a partial cross-sectional view of the tread portion.
[Explanation of symbols]
2 Tread part 3 Tread surface 5 Columnar material S Siping G1 Anti-slip rubber material E Tread end

Claims (3)

² to 40 parts by weight of a columnar material having a base area of 10 ^{-4 to} 4.0 mm ² and a length of 0.1 to 15 mm and an edge effect on a road surface are included in 100 parts by weight of the rubber base material. While forming at least a part of the tread surface using a rubber material for slip prevention,
A lengthwise direction of the columnar material is oriented at an angle of 40 to 90 ° with respect to a tread surface, and a siping formed by cutting after tire vulcanization molding is provided on the tread surface. Containing tires. The pneumatic tire according to claim 1, wherein the columnar material includes a glass fiber having a columnar shape or a prismatic shape. The tread surface is formed with at least one row of blocks in which blocks are arranged in the tire circumferential direction or a row of ribs continuous in the tire circumferential direction,
The pneumatic tire according to claim 1 or 2, wherein the durometer A hardness of the anti-slip rubber material is 40 to 60 °.

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