JP4044532B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can improve traveling performance and the like on icy and snowy roads.

  In recent years, in tires (for example, studless tires) with improved running performance on icy and snowy roads, organic or inorganic short fibers have been blended with tread rubber that comes in contact with the road surface. Such short fibers are known to be oriented substantially along the thickness direction of the tread rubber, in addition to those oriented randomly. The short fiber can increase the coefficient of friction on the icy and snowy road by mainly protruding from the tread rubber in a bowl shape and scratching the road surface (edge effect).

  In addition, this type of tire usually employs a block pattern in which a large number of blocks are formed on the tread surface, and this block has a large number of sipings (narrow grooves) extending substantially in the tire axial direction. Yes.

  Incidentally, a plurality of sipings are usually provided per block, and this siping is vulcanized by a knife blade provided in a tire vulcanizing mold. However, by pushing the knife blade into the rubber together with the rubber flow during vulcanization molding, the orientation of the short fibers and the like is irregularly disturbed, and the road surface scraping effect by the short fibers cannot be obtained sufficiently. 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 heavily worn and the tire life is remarkably shortened. In addition, although the tread rubber blended with the short fibers is generally effective on icy and snowy roads, there is a problem that the grip force is rather lowered on the normal dry asphalt road surface because the rubber contact area decreases.

  In the present invention, at least a part of the tread surface is formed using an anti-slip rubber material in which a columnar material having a predetermined shape is blended in 100 parts by weight of the rubber base material, and the length direction of the columnar material is set to the tread surface. And the tread surface includes a first grounding portion made of the anti-slip rubber material and a second grounding portion made of a rubber material not including a columnar material. Based on the above, it is an object to provide a pneumatic tire capable of suppressing a decrease in grip on a dry asphalt road surface while improving a running performance on an icy and snowy road.

In the invention according to claim 1, the bottom area is 10 ^{−4 to} 4.0 mm ² in 100 parts by weight of a rubber base material having a durometer A hardness of 40 to 60 ° in an atmosphere of −10 ° C. and a length. And forming at least a part of the tread surface using an anti-slip rubber material containing 2 to 40 parts by weight of a columnar material made of a material that exhibits an edge effect on the road surface.
While orienting the length direction of the columnar material at an angle of 40 to 90 ° with respect to the tread surface,
The tread surface includes a first grounding portion formed using the anti-slip rubber material, and a second grounding portion made of a rubber material not including a columnar material,
The tread surface has a block pattern in which blocks are arranged in parallel,
Moreover, the block surface is provided with an inclination angle θ of 0 to 60 ° with respect to the tire axial direction, and provided with siping that increases the edge component of the block,
In the siping, the arrangement pitch in the tire circumferential direction is 3 to 25 mm, the siping depth is 0.3 to 1.0 times the groove depth of the longitudinal groove 10, and the tread surface is the tread surface. The first grounding portion is provided at the center of the tire and the second grounding portion extends to the tread end on both sides of the first grounding portion, and the width of the first grounding portion in the tire axial direction is defined between the tread ends. It is characterized by being 0.4 to 0.6 times the tread width which is the distance in the tire axial direction.

  Further, in the invention of claim 1, the tread surface includes a first grounding portion made of a non-slip rubber column including a columnar material and a second grounding portion made of a rubber material not including a columnar material, Both on-ice performance and dry grip performance can be achieved. The columnar material is not particularly limited, but it preferably includes a glass fiber having a columnar shape or a prismatic shape in order to enhance the edge effect. The tread surface is useful for generating a large driving force by forming at least one row of blocks in which the blocks are arranged in the tire circumferential direction or a row of ribs continuous in the tire circumferential direction. Further, by setting the durometer A hardness of the rubber material for anti-slip to 40 to 60 °, it is possible to increase the adhesion with the road surface, further improve the ground contact property and further improve the running performance on icy and snowy roads. The “running performance” is a generic term for running and braking performance on icy and snowy roads. The tread surface refers to a surface that contacts a road surface under an internal pressure and a load determined by a standard such as JATMA by assembling a rim.

  In the invention according to claim 1, since the first grounding portion is provided at the center portion of the tread surface and the second grounding portions are provided on both sides thereof, the driving performance at the time of starting on a snowy road, acceleration, etc. In addition, it can improve grip when turning on dry asphalt roads. In this case, an anti-slip effect is obtained at the central portion of the tread surface where a large force is applied during driving. Therefore, by using the drive wheel in particular, it is possible to obtain a start-up and driving action with less slip even when traveling on an icy snowy road. At this time, the width of the first ground contact portion in the tire axial direction is set to 0.4 to 0.6 times the tread width that is the tire axial distance between the tread ends, for example, so that the grip on the dry asphalt road surface is achieved. It is possible to improve the power and driving performance on snowy roads in a well-balanced manner.

Hereinafter, an embodiment of the present invention will be described 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 development view of the tread surface thereof. The pneumatic tire 1 of the present embodiment includes a tread portion 2 and at least a part of a tread surface 3 that serves as a ground contact surface of the tread portion 2 is formed of an anti-slip rubber material G1, and travels on icy and snowy roads. It is configured as an improved so-called studless tire. That is, the tread surface 3 includes a first grounding portion 3a formed using the anti-slip rubber material G1 and a second grounding portion 3b made of the rubber material G2 not including the columnar material 5.

  The anti-slip rubber material G1 includes 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 base material, 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. Can be used.

  The columnar member 5 is made of a material that causes the anti-slip rubber material G1 to exert an edge effect on the road surface. That is, it is first necessary that the columnar material 5 is made of a material that is kneaded and dispersed in the rubber base material and does not disappear even by vulcanization. Further, the columnar member 5 can project an edge effect by projecting in a bowl shape from the surface of the rubber base material and scraping the road surface directly by the columnar member. In this case, the columnar member 5 is required to have a bending rigidity that does not easily break. Further, when the columnar material 5 falls off from the rubber surface due to progress of rubber wear or the like, the edge effect can also be indirectly exhibited by a small hole remaining on the rubber surface where the columnar material 5 is embedded thereafter. It is also possible to adsorb a water film on ice using the small holes.

  Examples of such materials for the columnar member 5 include, for example, organic materials such as nylon, polyester, aramid, rayon, vinylon, aromatic polyamide, cotton, cellulose resin, crystalline polybutadiene, 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 non-metallic material, particularly glass fiber, which has a small difference in wear rate from rubber. Further, the columnar member 5 may be subjected to a surface treatment or the like necessary for improving the adhesiveness with the rubber base material.

  Moreover, the compounding quantity of the columnar material 5 is 2-40 weight part with respect to 100 weight part of said rubber base materials, More preferably, it is 15-30 weight part. If the columnar material 5 is less than 2 parts by weight, the running performance on icy and snowy roads cannot be sufficiently improved. Conversely, if it exceeds 40 parts by weight, the crack resistance of the rubber tends to decrease.

In addition, the columnar material 5 is made of glass fiber in this example, and is preferably configured in a columnar shape or a prismatic shape, for example, as shown in FIGS. When the prismatic shape is used, the edge of the columnar material 5 itself is further increased by using a triangular prism shape or a hexagonal prism shape, and thus a higher edge effect can be expected. The bottom area A of the columnar member 5 is 10 ^{−4 to} 4.0 mm ² and the length L is 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 it is larger than 0.0 mm ² or the length L is larger than 15 mm, the columnar member 5 becomes too large, the adhesiveness to rubber is lowered, and the wear resistance and crack resistance are lowered. From such a viewpoint, it is particularly desirable that the bottom area A of the columnar member 5 is 10 ^{−2 to} 4.0 mm ² and the length L is 0.3 to 15 mm. The bottom area A and the length L are both average values.

  Further, it is desirable that the anti-slip rubber material G1 has a durometer A hardness of 40 to 60 °, more preferably 45 to 60 ° when measured in an atmosphere of −10 ° C. As a result, flexibility is ensured even at low temperatures, and the contact performance with the road surface is further improved to improve the running performance on icy and snowy roads, and it also helps maintain the driving stability on the dry asphalt road surface. The “durometer A hardness” is a rubber hardness according to durometer type A based on JIS-K6253 and is measured so as to have a hardness (in the tire radial direction) of the rubber material for anti-slip G1.

  Further, most of the columnar material 5 (for example, 90% or more) is oriented in a substantially vertical state in which the length direction is an angle of 40 to 90 ° with respect to the tread surface 3. As a method of obtaining the rubber in which the columnar members 5 are oriented in this way, for example, a calendar roll r can be used as shown in FIG. As is well known, unvulcanized rubber material m in which predetermined chemicals necessary for vulcanization molding are blended as necessary in addition to rubber base material and columnar material 5 is rolled with calender rolls r and r. In this case, the length direction of the columnar material 5 is along the rolling direction X.

  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. Then, by using this rubber laminate so that the Z direction is the tire radial direction, a material in which the columnar members 5 are oriented substantially perpendicular to the tread surface 3 can be obtained.

  4B, the rubber sheet g in which the columnar material 5 is 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 material 5. It is also possible to obtain the same material.

  Then, these materials are molded as a tread rubber 4 bonded to a rubber material G2, a wing rubber 4c and the like that do not include the columnar material 5 for the second grounding portion 3b, and a raw tire cover is molded using this. . Moreover, the pneumatic tire 1 can be manufactured by vulcanizing the green tire cover. In the pneumatic tire 1 having such a tread surface 3, a small hole on the rubber surface formed by the oriented columnar member 5 or the like effectively scratching the road surface or the columnar member 5 falling off the rubber. As a result, the friction coefficient between the snowy road and the road can be increased, and the running performance can be greatly improved.

  Moreover, the pneumatic tire 1 of this embodiment is provided with a siping S formed on the tread surface 2 by cutting after tire vulcanization molding. In this example, all the siping S is removed by cutting after tire vulcanization molding. What is formed is illustrated. In general, as shown in FIG. 5, when the siping S is molded using a knife blade K of a mold M or the like during vulcanization, the columnar material 5 present in the flowing rubber is a rubber flow caused by the pressure of the knife blade K. However, in this embodiment, since the orientation of the columnar material 5 is already fixed by vulcanized rubber, the orientation of the columnar material 5 is prevented from being disturbed even if the siping S is formed by cutting. Is done. Therefore, in the pneumatic tire of this embodiment, since the disorder of the orientation state of the columnar material 5 after vulcanization is very small, the effect of improving the running performance on icy and snowy roads can be further expected. Further, since the orientation of the columnar member 5 is improved as compared with the conventional one, for example, even if the rubber hardness of the anti-slip rubber material G1 is increased, the same performance on ice can be exhibited. The wear resistance of the material G1 can be improved and the tire life can be extended.

  As shown in FIG. 2, the tread surface 3 is formed in a block pattern having 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. In each block B, at least one, preferably a plurality of sipings S are formed. Instead of the block row BL, a grounding portion may be a rib row that continues in the tire circumferential direction. The siping S is disposed, for example, 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.

  Further, the siping S can be configured in various shapes such as a zigzag shape, a wave 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 pitch of the siping S in the tire circumferential direction is 3 to 25 mm, and the siping depth is 0.3 to 1.0 times the groove depth of the longitudinal groove 10.

  Further, the siping S can be configured in various shapes such as a zigzag shape, a wave 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 pitch of the siping S in the tire circumferential direction is preferably 3 to 25 mm, for example, and the siping depth is preferably 0.3 to 1.0 times the depth of the longitudinal groove 10.

  On the other hand, the anti-slip rubber material G1 blended with the columnar material 5 produces an effective frictional force on icy and snowy roads, while the ground contact area of rubber is reduced on ordinary dry asphalt road surfaces. There is a problem that the grip force is reduced. Therefore, in the present embodiment, the on-ice running performance and the dry grip performance are compatible by including the second contact portion 3b made of the rubber material G2 not including the columnar material 5 in the tread surface 3.

  In addition, the running performance of the tire varies depending on which part of the tread surface 3 the first ground contact portion 3a is disposed. The tread surface 3 of the present example is provided with the first grounding portion 3a at the center of the tread surface 3, and the second grounding portion 3b extending to the tread end E on both sides thereof. In general, since a large force acts on the center of the tread surface 3 at the time of start, acceleration, etc., the anti-slip rubber material G1 is disposed on this part, so that the drive performance at the time of start, acceleration, etc. on icy and snowy roads. To help improve. That is, it is suitable as a drive wheel tire to be mounted on the drive wheel. On the other hand, as described above, the second ground contact portion 3b made of the rubber material G2 not including the columnar material 5 is provided on the side portion in the axial direction of the tread surface 3 so that the vehicle runs on the dry asphalt road surface. The grip power at the time is increased, and the decrease in steering stability is suppressed.

  Further, at this time, the width W1 in the tire axial direction of the first ground contact portion 3a (including the groove width not grounded) is, for example, the tire axial distance between the tread ends E and E that are the axial outer ends of the tread surface 3. By making the tread width TW 0.2 to 0.6 times, more preferably 0.3 to 0.6 times, the grip force on the dry asphalt road surface and the driving performance on the icy and snowy roads are improved in a balanced manner. sell. When the width W1 of the first ground contact portion 3a is less than 0.2 times the tread width TW, the ground contact width of the first ground contact portion 3a is reduced, so that it is difficult to obtain a high frictional force on icy and snowy roads. On the other hand, if it exceeds 0.6 times, the ground contact width of the second ground contact portion 3b becomes small, so that the reduction in grip force on the dry asphalt road surface becomes relatively large. The first ground contact portion 3a is arranged on the tire equator C with its center substantially aligned.

In FIG. 6, the tread surface 3 includes the second grounding portion 3 b at the center of the tread surface 3, and the first grounding portion 3 a is merely illustrated on both sides thereof . In general, since a large lateral force acts on the side portion of the tread surface 3 (so-called shoulder portion) during turning, the anti-slip rubber material G1 is provided on this side portion, thereby improving the turning performance particularly on icy and snowy roads. To help. Such a tire can be employed when it becomes 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 grounding portion 3b made of the rubber material G2 not including the columnar material 5 at the center portion of the tread surface 3, the grip on the dry asphalt road surface is improved, and the driving performance and the like are reduced. It is suppressed.

  In such 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 is desirable. This is because this range mainly bears a large lateral force during turning.

  Moreover, the tread surface 3 of this example illustrates the rubber material G2 that does not include the columnar material 5 in the range of the small width W3 from the tread ends E and E to the inside in the tire axial direction. The width W3 is 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 does not include the columnar material 5 around the tread edge E because the rubber material G1 includes the columnar material 5 and tends to be slightly inferior in wear resistance, crack resistance, tear resistance, and the like. Is exposed to a small width to effectively prevent rubber chipping and cracking at the tread edge E and improve the appearance of the tire 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.

The siping S includes a first siping S1 extending including the first grounding portion 3a and a second siping S2 extending only the second grounding portion 3b. For example, only the second siping S2 is irrelevant to the anti-slip rubber material G2, and is vulcanized by the knife blade K of the mold M. That is, at least the first siping S1 is formed by cutting after tire vulcanization molding. This can reduce the decrease in tire productivity. Moreover, as shown in FIG. 7, you may provide the 1st earthing | grounding part 3a which consists of the said rubber material G1 for anti-slip in both the center part and side part of the tread surface 3. As shown in FIG. In this case, although the improvement of the grip force on the dry asphalt road surface becomes small, it becomes possible to simultaneously improve both performances such as driving and turning on an icy and snowy road.

Next, the tires shown in FIG. 1 (Examples 1 and 2) (Reference Example 1), the tires shown in FIGS. 6 and 7 (Reference Examples 2 to 7), and Comparative Examples 1 and 2 were prototyped, and the driving performance on ice was Tests on ice turning performance, dry grip, wet grip, etc. For comparison, a summer tire (Comparative Example 1) that does not have a ground contact surface made of an anti-slip rubber material, and a tire (Comparative Example 2) in which the entire tread surface is formed of an anti-slip rubber material are also prototyped. To evaluate the performance. The test method is as follows.

<Drive performance on ice>
The road surface friction coefficient on ice was measured and evaluated by an index with Comparative Example 3 taken as 100. The larger the value, the better. The friction coefficient was measured by using an inside drum and setting the slip rate to two types of 10% and 60% under conditions of an air temperature of −1 ° C. and a drum speed of 5 km / h.

<Swivel performance on ice>
At an air temperature of −1 ° C., a steady circular turn (about 40 R) was performed on the ice road surface at a speed of 30 to 40 km / h, and the time was measured. The larger the value, the better.

<Dry grip performance>
The test vehicle equipped with the test tire was entered on the course of the asphalt road surface with a radius of 100 m while gradually increasing the speed, the lateral acceleration (lateral G) was measured, and the front wheels at a speed of 50-80 km / h The average lateral G was calculated. A result is displayed by the index | exponent which sets the comparative example 1 to 100, and it is so favorable that a numerical value is large.

<Wet grip performance>
The test vehicle equipped with the test tire was entered while increasing the speed stepwise on a course with a water depth of 5 mm and a length of 20 m on an asphalt road surface with a radius of 100 m, and the lateral acceleration (lateral G) was increased. Measurement was made to calculate the average lateral G of the front wheels at a speed of 50 to 80 km / h. A result is displayed by the index | exponent which sets the comparative example 1 to 100, and it is so favorable that a numerical value is large.
The test results are shown in Tables 1 and 2.

  As a result of the test, it was confirmed that the tire of the example improved the dry grip performance as compared with Comparative Example 2 while improving the braking performance on ice. In particular, in the case shown in FIG. 7, it was confirmed that the driving performance on ice and the turning performance on ice in the case shown in FIG. 8 were improved in good balance with the dry grip performance.

It is a fragmentary sectional view of the tread part which is one embodiment of the present invention. It is a development view of the tread surface. (A)-(d) is the schematic which illustrates a columnar material. (A), (b) is the schematic explaining the manufacturing method of the rubber material for anti-slip | skid. It is a fragmentary sectional view along the circumferential direction of all types. It is a fragmentary sectional view of the tread part which is other embodiments. It is a fragmentary sectional view of the tread part which is other embodiments.

Explanation of symbols

2 Tread part 3 Tread surface 3a First grounding part 3b Second grounding part 5 Columnar material S Siping G1 Anti-slip rubber material E Tread end

Claims (1)

The bottom area is 10 ^{−4 to} 4.0 mm ² and the length is 0.1 to 15 mm in 100 parts by weight of a rubber base material having a durometer A hardness of 40 to 60 ° in an atmosphere of −10 ° C. While forming at least a part of the tread surface using an anti-slip rubber material containing 2 to 40 parts by weight of a columnar material made of a material that exhibits an edge effect,
While orienting the length direction of the columnar material at an angle of 40 to 90 ° with respect to the tread surface,
The tread surface includes a first grounding portion formed using the anti-slip rubber material, and a second grounding portion made of a rubber material not including a columnar material,
The tread surface has a block pattern in which blocks are arranged in parallel,
Moreover, the block surface is provided with an inclination angle θ of 0 to 60 ° with respect to the tire axial direction, and provided with siping that increases the edge component of the block,
In the siping, the arrangement pitch in the tire circumferential direction is 3 to 25 mm, and the siping depth is 0.3 to 1.0 times the groove depth of the longitudinal groove 10,
The tread surface includes the first grounding portion at the center of the tread surface and the second grounding portion extending to the tread end on both sides thereof.
The pneumatic tire according to claim 1, wherein a width of the first ground contact portion in a tire axial direction is 0.4 to 0.6 times a tread width which is a tire axial distance between the tread ends.

Images