JP6075165B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which an adhesive rubber layer is interposed between a carcass layer and an inner liner layer. More specifically, the present invention relates to a pneumatic tire capable of reducing road noise and improving durability. .

  In a pneumatic tire, it is required to improve durability so that it can sufficiently withstand long-time continuous running. In particular, since the shoulder portion of a pneumatic tire tends to generate heat during traveling, it is required to efficiently release the heat accumulated in the shoulder portion to the outside of the tire. As a means for releasing the heat accumulated inside the tire to the outside of the tire, for example, embedding a rubber layer having high thermal conductivity in the sidewall portion (see, for example, Patent Document 1) has been proposed. However, it is not always preferable to add such a rubber layer having high thermal conductivity to the sidewall portion from the viewpoint of weight reduction of the tire.

  On the other hand, a method of suppressing heat generation itself by reducing the thickness (side gauge) of the sidewall portion of the pneumatic tire is also conceivable. However, if the side gauge is made thinner, the circumferential rigidity of the tire is lowered, the noise level of the booming noise is increased, and the road noise is deteriorated. Therefore, it is necessary to consider road noise when improving the durability of a pneumatic tire.

JP 2009-292415 A

  An object of the present invention is to provide a pneumatic tire capable of reducing road noise and improving durability.

  In order to achieve the above object, the pneumatic tire of the present invention has at least one carcass layer mounted between a pair of bead portions, and at least two belt layers are disposed on the outer peripheral side of the carcass layer in the tread portion. In the pneumatic tire in which an inner liner layer is disposed along the carcass layer on the inner surface of the tire, an adhesive rubber layer is interposed between the carcass layer and the inner liner layer, and the outermost radial direction of the belt layer In the region overlapping with the edge portion of the outermost belt layer located on the outermost belt layer, the adhesive rubber layer contains fine carbon fibers, and the tread center side boundary position of the fine carbon fiber-containing region of the adhesive rubber layer is set to the edge of the outermost belt layer. It is arranged on the inner side in the tire width direction than the portion, and the bead side boundary position of the fine carbon fiber-containing region of the adhesive rubber layer is changed from the tire maximum width position to the tire diameter. It is characterized in that towards the direction inside and outside are arranged within a range of up to 10 percent of each tire section height.

  In the present invention, the heat generated in the shoulder portion of the pneumatic tire is diffused in a wider range by including fine carbon fibers having high thermal conductivity in the adhesive rubber layer in the region overlapping the edge portion of the outermost belt layer. At the same time, it is discharged to the tire lumen side and the heat is prevented from staying locally, so that the durability of the pneumatic tire can be improved. In particular, since the adhesive rubber layer is adjacent to the carcass layer and effectively suppresses heat generation of the carcass layer, the durability improving effect can be enhanced by using the adhesive rubber layer as a heat dissipation means.

  Further, when fine carbon fibers are contained in the adhesive rubber layer in the above region, the adhesive rubber layer increases the circumferential rigidity of the tire, so that road noise can be reduced. In addition, the adhesive rubber layer is a member generally used for bonding the carcass layer and the inner liner layer, and the member is used as a heat dissipation means, so that a substantial weight increase does not occur. Furthermore, since fine carbon fibers have good binding properties to rubber like carbon black, the adhesion based on the adhesive rubber layer is not lowered. In addition, the adhesive rubber layer can be extruded as a sheet material, but it can be easily obtained by blending fine carbon fibers in a part of the rubber material supplied at that time, which is a point of productivity. But it is effective.

  In the present invention, the tread center side boundary position of the fine carbon fiber-containing region of the adhesive rubber layer is closer to the tire than the position of 20% of the width of the outermost belt layer from the edge of the outermost belt layer toward the inner side in the tire width direction. It is preferable to arrange in the width direction inner side. Thereby, the area | region which should thermally radiate is fully ensured and durability of a pneumatic tire can be improved more effectively.

  When the fine carbon fiber-containing region of the adhesive rubber layer is divided into a first region on the tread center side and a second region on the bead side, the thickness of the adhesive rubber layer in the second region is larger than the thickness in the first region. Enlarging and arranging the boundary position between the first region and the second region within the range of 0% to 10% of the width of the outermost belt layer from the edge of the outermost belt layer toward the outer side in the tire width direction. Is preferred. Thus, by relatively increasing the thickness of the adhesive rubber layer in the second region, it is possible to increase the circumferential rigidity of the tire and enhance the effect of reducing road noise.

  At this time, the thickness of the adhesive rubber layer in the second region is 0.5 mm to 2.0 mm, and the thickness of the adhesive rubber layer in the region outside the second region is 0.3 mm to 0.5 mm. Is preferred. As a result, the durability improvement effect and the road noise reduction effect can be maximized.

  The adhesive rubber layer preferably contains 3 to 15 parts by weight of fine carbon fibers with respect to 100 parts by weight of rubber. Thereby, the effect of improving durability can be obtained without reducing the adhesiveness of the adhesive rubber layer. The fine carbon fiber preferably has a diameter of 1 μm to 50 μm and an aspect ratio of 4 to 100. When such fine carbon fibers are blended in the adhesive rubber layer, they greatly contribute to improving the durability of the pneumatic tire based on its thermal conductivity.

  It is preferable to provide a plurality of recesses having a timple shape on the tire inner surface. Thereby, since the surface area of the tire inner surface is increased, it is possible to enhance the heat dissipation effect based on the adhesive rubber layer.

  In the present invention, the tire cross-sectional height is measured in a state in which a pneumatic tire is assembled to a standard rim. Other dimensions are measured from cut samples of pneumatic tires.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is sectional drawing which shows the principal part of the pneumatic tire of FIG. FIG. 2 is a development view showing an inner surface of the pneumatic tire of FIG. 1. It is a top view which shows the recessed part which has the dimple shape formed in the inner surface of the pneumatic tire of FIG. It is sectional drawing which shows the dimple formed in the inner surface of the pneumatic tire of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a pneumatic tire according to an embodiment of the present invention, and CL is a tire equatorial plane. 1 and 2, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. Two carcass layers 4 including a plurality of reinforcing cords extending in the tire radial direction are mounted between the pair of bead portions 3 and 3, and the end portions of these carcass layers 4 are arranged around the bead core 5 from the inside of the tire to the outside. It is folded back. A bead filler 6 made of a rubber composition having a high hardness is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the carcass layer 4.

  Two belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layer 7 includes an innermost belt layer 7A located on the inner and outer sides in the tire radial direction and an outermost belt layer 7B located on the outermost side in the tire radial direction. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. A belt cover layer 8 formed by winding a reinforcing cord in the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7 in order to enhance high-speed durability. The belt cover layer 8 preferably has a jointless structure in which a strip material formed by aligning at least one reinforcing cord and covering with rubber is continuously wound substantially at 0 ° with respect to the tire circumferential direction. . Further, the belt cover layer 8 may be disposed so as to cover the entire width direction of the belt layer 7, or may be disposed so as to cover only the outer edge portion of the belt layer 7 in the width direction.

  On the other hand, an inner liner layer 9 is disposed along the carcass layer 4 on the tire inner surface. An adhesive rubber layer 10 is interposed between the carcass layer 4 and the inner liner layer 9, and the carcass layer 4 and the inner liner layer 9 are bonded to each other by the adhesive rubber layer 10.

  In the pneumatic tire, fine carbon fibers are blended in the adhesive rubber layer 10 in a region overlapping the edge portion BE of the outermost belt layer 7B located on the outermost side in the tire radial direction in the belt layer 7. That is, the adhesive rubber layer 10 contains fine carbon fibers in the rubber composition in the fine carbon fiber-containing region X (see FIG. 2), but does not contain fine carbon fibers in other regions.

  The tread center side boundary position P1 of the fine carbon fiber-containing region X of the adhesive rubber layer 10 is disposed on the inner side in the tire width direction from the edge portion BE of the outermost belt layer 7B, and more preferably, the edge of the outermost belt layer 7B. The portion BE is disposed on the inner side in the tire width direction from the position of 20% of the width W of the outermost belt layer toward the inner side in the tire width direction from the portion BE. That is, the tread center side boundary position P1 of the fine carbon fiber-containing region X of the adhesive rubber layer 10 is disposed within the range Y1 on the inner side in the tire width direction from the edge portion BE of the outermost belt layer 7B, and more preferably From the edge BE of the outer side belt layer 7B toward the inner side in the tire width direction, the outer side belt layer is arranged in a range Y2 on the inner side in the tire width direction from the position of 20% of the width W of the outermost belt layer.

  Further, the bead side boundary position P2 of the fine carbon fiber-containing region X of the adhesive rubber layer 10 is within a range Y3 from the tire maximum width position Pmax to 10% of the tire cross-section height H from the tire radial direction inside to the outside. Is arranged.

  In the pneumatic tire described above, the heat generated in the shoulder portion of the pneumatic tire is obtained by causing the adhesive rubber layer 10 to contain fine carbon fibers having high thermal conductivity in the region X overlapping the edge portion BE of the outermost belt layer 7B. Is diffused in a wider range and released to the tire lumen side, and heat is prevented from staying locally, so that the durability of the pneumatic tire can be improved. In particular, the adhesive rubber layer 10 is adjacent to the carcass layer 4 and effectively suppresses the heat generation of the carcass layer 4. Therefore, the durability improving effect can be enhanced by using the adhesive rubber layer 10 as a heat dissipation means.

  In addition, when fine carbon fibers are contained in the adhesive rubber layer 10 in the region X, the adhesive rubber layer 10 increases the circumferential rigidity of the tire, so that road noise can be reduced. In addition, since the adhesive rubber layer 10 is a member inserted between the carcass layer 4 and the inner liner layer 9 in order to bond them, there is no substantial increase in weight. Further, since fine carbon fibers have a good binding property to rubber like carbon black, the adhesiveness of the adhesive rubber layer 10 is not lowered. The adhesive rubber layer 10 can be extruded as a sheet material, but can be easily obtained by blending fine carbon fibers into a part of the rubber material supplied at that time.

  Here, the tread center side boundary position P1 of the fine carbon fiber-containing region X of the adhesive rubber layer 10 needs to be disposed on the inner side in the tire width direction from the edge portion BE of the outermost belt layer 7B. The fine carbon fibers of the adhesive rubber layer 10 are preferably disposed on the inner side in the tire width direction than the position of 20% of the width W of the outermost belt layer 7B from the edge portion BE of the layer 7B toward the inner side in the tire width direction. If the containing region X does not sufficiently extend below the outermost belt layer 7B, the durability improving effect is lowered. By arranging the tread center side boundary position P1 of the fine carbon fiber-containing region X in the range Y2, it is possible to sufficiently secure a region to be radiated and to improve the durability of the pneumatic tire more effectively. In particular, since heat tends to be generated during traveling in the vicinity of the edge portion BE of the outermost belt layer 7B in the tread portion 1, it is effective to provide the fine carbon fiber-containing region X so as to include this portion.

  On the other hand, the bead side boundary position P2 of the fine carbon fiber-containing region X of the adhesive rubber layer 10 is within a range Y3 from the tire maximum width position Pmax to 10% of the tire cross-section height H from the tire radial direction inside and outside. However, if the fine carbon fiber-containing region X of the adhesive rubber layer 10 extends to the bead side from the range Y3, the longitudinal spring constant of the tire is excessively increased and the riding comfort is reduced. Resulting in. Conversely, if the fine carbon fiber-containing region X of the adhesive rubber layer 10 does not reach the range Y3, the durability improving effect and the road noise reducing effect are insufficient.

  In the pneumatic tire, when the fine carbon fiber-containing region X of the adhesive rubber layer 10 is divided into the first region X1 on the tread center side and the second region X2 on the bead side, the first region X1 of the adhesive rubber layer 10 The thickness of the adhesive rubber layer 10 in the second region X2 is made larger than the thickness of the outermost belt layer 7B from the edge portion BE of the outermost belt layer 7B at the boundary position P3 between the first region X1 and the second region X2. It is preferable that the outermost belt layer 7B is disposed in the range of 0% to 10% of the width W toward the outside. Thus, by relatively increasing the thickness of the adhesive rubber layer 10 in the second region X2, it is possible to increase the circumferential rigidity of the tire and enhance the road noise reduction effect.

  When the thickness of the adhesive rubber layer 10 is changed as described above, the thickness of the adhesive rubber layer 10 in the second region X2 is set to 0.5 mm to 2.0 mm, and is out of the second region X2 of the adhesive rubber layer 10. The thickness in the region (the region not including the first region X1 and the fine carbon fiber) is preferably 0.3 mm to 0.5 mm. As a result, the durability improvement effect and the road noise reduction effect can be maximized. Here, if the thickness of the adhesive rubber layer 10 in the second region X2 is larger than 2.0 mm, the heat dissipation performance is hindered because the portion is too thick, and the durability improving effect is lowered. On the other hand, if the thickness of the adhesive rubber layer 10 in the region outside the second region X2 is smaller than 0.3 mm, the adhesion between the carcass layer 4 and the inner liner layer 9 is lowered.

  The adhesive rubber layer 10 may contain 3 to 15 parts by weight of fine carbon fiber with respect to 100 parts by weight of rubber. Thereby, the durability improving effect can be obtained without lowering the adhesiveness of the adhesive rubber layer 10. Here, if the blending amount of the fine carbon fiber with respect to 100 parts by weight of the rubber is less than 3 parts by weight, the thermal conductivity decreases, and conversely if it exceeds 15 parts by weight, the adhesiveness decreases.

  Although the diameter of a fine carbon fiber is not specifically limited, For example, it is good in the range of 1 micrometer-50 micrometers, More preferably, it exists in the range of 10 micrometers-30 micrometers. If the diameter of the fine carbon fiber is too small, the elastic force of the rubber containing the fine carbon fiber is insufficient, so that the effect of reducing road noise is reduced. Conversely, if the diameter is too large, the surface area of the fine carbon fiber is reduced and the adhesion rubber layer 10 is bonded. Sex is reduced.

  The aspect ratio of the fine carbon fiber is not particularly limited, but is, for example, in the range of 4 to 100, and more preferably in the range of 20 to 60. When the aspect ratio of the fine carbon fiber is smaller than 4, the thermal conductivity is lowered. On the other hand, when the aspect ratio is larger than 100, the elongation characteristic is lowered, and the durability improving effect is lowered.

  FIG. 3 shows an inner surface of the pneumatic tire, and FIGS. 4 and 5 show a dimple-shaped recess formed on the inner surface. As shown in FIGS. 3 to 5, a plurality of concave portions 11 having a timple shape are formed on the inner surface of the pneumatic tire. Although the recessed part 11 can be provided in the whole region of an inner surface of the tire, it is particularly preferable to selectively dispose the recessed part 11 in a part corresponding to the fine carbon fiber-containing region X of the adhesive rubber layer 10 as shown in FIG. Since the surface area of the tire inner surface is increased by providing the tire inner surface with the plurality of concave portions 11 having the timple shape, the heat dissipation effect based on the adhesive rubber layer 10 can be enhanced.

  As shown in FIGS. 4 and 5, the recess 11 has a timple shape that gradually becomes deeper from the peripheral part toward the center part, but the diameter D is in the range of 3.0 mm to 8.0 mm, for example. And the depth d is preferably in the range of 0.3 mm to 0.5 mm. The concave portion 11 having such dimensions can be formed on the inner surface of the tire without impairing the function of the inner liner layer 9, and contributes to improvement in heat dissipation.

  The tire size is 215 / 60R16 95V, two carcass layers are mounted between a pair of bead portions, two belt layers are arranged on the outer periphery side of the carcass layer in the tread portion, and along the carcass layer on the inner surface of the tire In a pneumatic tire in which an inner liner layer is disposed and an adhesive rubber layer is interposed between the carcass layer and the inner liner layer, the thickness of the adhesive rubber layer, the presence or absence of fine carbon fibers in the adhesive rubber layer, the adhesive rubber layer In the tread center side boundary position P1 of the fine carbon fiber-containing region, the bead side boundary position P2 of the fine carbon fiber-containing region of the adhesive rubber layer, the thickness in the first region of the adhesive rubber layer, and the second region of the adhesive rubber layer The pneumatic tires of conventional examples, examples 1 to 11 and comparative examples 1 and 2 in which the thickness and the presence or absence of dimples on the tire inner surface were set as shown in Table 1 were manufactured.

  As the tread center side boundary position P1 of the fine carbon fiber-containing region of the adhesive rubber layer, the distance from the edge portion of the outermost belt layer to the inner side in the tire width direction is described, and the distance is a ratio to the width W of the outermost belt layer. Expressed in As the bead side boundary position P2 of the fine carbon fiber-containing region of the adhesive rubber layer, the distance in the tire radial direction from the tire maximum width position is described, and the distance is expressed as a ratio to the tire cross-section height H. For the position P2, a positive value means that it is inside in the tire radial direction from the tire maximum width position, and a negative value means that it is outside in the tire radial direction from the tire maximum width position.

  These test tires were evaluated for durability, road noise, and riding comfort by the following evaluation methods, and the results are also shown in Table 1.

durability:
Each test tire is assembled on a 16 x 7 JJ wheel and mounted on an indoor drum testing machine, the air pressure is 240 kPa, the load is 1.5 times the regular load specified by JATMA, and the speed is 80 km / h. The distance traveled until the tire failed and was unable to run was measured. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the durability.

Road noise:
Each test tire was assembled on a 16 × 7 JJ wheel and mounted on a front-wheel drive test vehicle, and the air pressure was 240 kPa, and a sensory evaluation was performed by a panelist at the test course. The evaluation results are shown as an index with the conventional example being 100. A larger index value means less road noise.

Ride comfort:
Each test tire was assembled on a 16 × 7 JJ wheel and mounted on a front-wheel drive test vehicle, and the air pressure was 240 kPa, and a sensory evaluation was performed by a panelist at the test course. The evaluation results are shown as an index with the conventional example being 100. A larger index value means better ride comfort.

  As is clear from Table 1, the tires of Examples 1 to 11 were improved in durability and road noise in comparison with the conventional example, and maintained good riding comfort. On the other hand, in the tire of Comparative Example 1, the bead side boundary position P2 of the fine carbon fiber-containing region of the adhesive rubber layer is too close to the bead portion. Was getting worse. In the tire of Comparative Example 2, the bead side boundary position P2 of the fine carbon fiber-containing region of the adhesive rubber layer was too close to the tread portion, so that the road noise reduction effect was not obtained and the durability improvement effect was also reduced. .

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 9 Inner liner layer 10 Adhesive rubber layer 11 Concave part X Fine carbon fiber containing area | region

Claims (7)

  At least one carcass layer is mounted between a pair of bead portions, at least two belt layers are disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer is disposed along the carcass layer on the tire inner surface. In the pneumatic tire, an adhesive rubber layer is interposed between the carcass layer and the inner liner layer, and the belt layer overlaps with an edge portion of the outermost belt layer located on the outermost side in the tire radial direction. Fine carbon fibers are contained in the adhesive rubber layer, and the tread center side boundary position of the fine carbon fiber-containing region of the adhesive rubber layer is disposed on the inner side in the tire width direction from the edge portion of the outermost belt layer, and the adhesive rubber layer The bead side boundary position of the fine carbon fiber containing region of the tire cross-sectional height from the tire maximum width position toward the tire radial direction inside and outside A pneumatic tire characterized by being located within the range of 0%.   The tread center side boundary position of the fine carbon fiber containing region of the adhesive rubber layer is in the tire width direction from the position of 20% of the width of the outermost belt layer toward the inner side in the tire width direction from the edge portion of the outermost belt layer. The pneumatic tire according to claim 1, wherein the pneumatic tire is disposed inside.   When the fine carbon fiber-containing region of the adhesive rubber layer is divided into a first region on the tread center side and a second region on the bead side, the thickness of the adhesive rubber layer in the second region is larger than the thickness in the first region. And the boundary position between the first region and the second region is 0% to 10% of the width of the outermost belt layer from the edge of the outermost belt layer toward the outer side in the tire width direction. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire is disposed within a range of.   The thickness of the adhesive rubber layer in the second region is set to 0.5 mm to 2.0 mm, and the thickness of the adhesive rubber layer in a region outside the second region is set to 0.3 mm to 0.5 mm. The pneumatic tire according to claim 3.   The pneumatic tire according to any one of claims 1 to 4, wherein the adhesive rubber layer contains 3 to 15 parts by weight of the fine carbon fiber with respect to 100 parts by weight of rubber.   The pneumatic tire according to claim 1, wherein the fine carbon fiber has a diameter of 1 μm to 50 μm and an aspect ratio of 4 to 100.   The pneumatic tire according to claim 1, wherein a plurality of concave portions having a timple shape are provided on the inner surface of the tire.

Images