JP6484044B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pneumatic tire capable of improving on-ice performance and wet performance, and a method for manufacturing the same.

  Patent Document 1 below proposes a pneumatic tire in which the tread rubber is formed from a soft rubber material containing short fibers in order to improve the performance on ice. The soft rubber material containing short fibers is, for example, a rubber base material and short fibers are kneaded with a mixer or the like, and then extruded into a cross-sectional shape of tread rubber. At this time, the short fibers are oriented with the major axis direction along the rubber extrusion direction.

JP 2000-264015 A

  A tread rubber in which short fibers are oriented along one direction (for example, the tire circumferential direction) is expected to have an edge effect in the tire axial direction. However, it is difficult for the tread rubber to exhibit the fiber edge effect in the tire circumferential direction, and there is room for further improvement in terms of improving the on-ice performance and wet performance of the tire.

  The present invention has been devised in view of the above circumstances, and has as its main object to provide a pneumatic tire capable of improving the performance on ice and the wet performance, and a method for producing the same.

  A first invention of the present application is a pneumatic tire having a tread rubber, wherein the tread rubber includes a plurality of fiber chips in which fibers are arranged in a net shape.

  In another aspect of the first aspect of the present invention, the fiber chip may include one disposed along a ground surface of the tread rubber.

  In another aspect of the first invention, the fiber chip may have a rectangular shape with a side of 5 to 15 mm.

  In another aspect of the first invention, the fiber chip may be circular with a maximum diameter of 5 to 15 mm.

  In another aspect of the first invention, the total mass of the tread rubber fibers may be in the range of 5 to 15% of the mass of the rubber component.

  In another aspect of the first invention, the fibers may be natural fibers or synthetic fibers.

  In another aspect of the first invention, the fibers may have a fineness of 900-2100 dtex.

  2nd invention of this application is a manufacturing method of a pneumatic tire, Comprising: The process of forming the raw tire containing unvulcanized tread rubber is included, The tread rubber is arranged in a rubber polymer, and at least fibers are arranged in a network. It is characterized in that it is molded using a rubber composition in which a fiber chip composite in which a fiber chip and a rubber piece vulcanized more than the rubber polymer are integrated is mixed.

  In another aspect of the second invention, the rubber piece of the fiber chip composite may be semi-vulcanized.

  The tread rubber of the pneumatic tire of the present invention includes a plurality of fiber chips in which fibers are arranged in a net shape. In such a fiber chip, fibers arranged in a mesh shape can exhibit an edge effect with a good balance in multiple directions, not in one direction. Therefore, the tire of the present invention can exhibit excellent on-ice performance and wet performance.

It is sectional drawing of the pneumatic tire which shows one Embodiment of this invention. It is a partial expansion perspective view of the tread rubber of FIG. It is a top view which shows one Embodiment of a fiber chip. It is sectional drawing of the unvulcanized tread rubber used when manufacturing the pneumatic tire of this invention. It is a perspective view which shows an example of a fiber chip composite.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) showing an embodiment of the present invention. The tire of this embodiment is shown for heavy loads such as trucks and buses, but is not limited to such tires.

  As shown in FIG. 1, the tire of the present embodiment includes a carcass 5 extending from the tread portion 2 through the sidewall portion 3 to the bead portion 4, a belt layer 6 disposed on the outer side in the tire radial direction of the carcass 5, And a tread rubber 7 disposed on the outer side of the belt layer 6 in the tire radial direction.

  FIG. 2 shows an enlarged perspective view of a part of the tread rubber 7 of the present embodiment. The tread rubber 7 forms a ground contact surface 2S of the tread portion 2. In order to improve traveling performance on icy road surfaces and wet road surfaces, the ground contact surface 2S needs to be configured to exhibit a high frictional force against the road surface. The tread rubber 7 according to this embodiment includes a rubber portion 8 and a plurality of fiber chips 9. If necessary, the tread rubber 7 may be blended with various additives.

  The rubber portion 8 constitutes a main portion of the tread rubber 7, and for example, a rubber polymer such as a diene rubber is preferably used.

  The fiber chips 9 are a plurality of relatively small fiber pieces arranged in a rubber portion 8 as a matrix, and are arranged so that all or part of the fiber chips 9 are exposed on the ground contact surface 2S of the tread rubber 7. Further, at the present stage, the fiber chip 9 that is not exposed to the grounding surface 2S can be exposed to the grounding surface 2S at the subsequent wear stage of the tread rubber 7.

  Each fiber chip 9 is formed to include fibers 10 arranged in a net shape having a plurality of meshes. In a preferred embodiment, the fiber chip 9 includes one disposed along the ground contact surface 2S of the tread rubber 7, more preferably one exposed on the ground contact surface 2S of the tread rubber 7 and disposed along the ground contact surface 2S. (An example of such a fiber chip 9 is depicted on the uppermost side of FIG. 2). The fiber chip 9 exhibits the edge effect in a balanced manner in multiple directions when the net-like fibers 10 are in contact with the road surface, and as a result, the on-ice performance and wet performance of the tire can be improved.

  Furthermore, the fiber chip 9 (for example, shown by 9A and 9B in FIG. 2) exposed to the ground contact surface 2S of the tread rubber 7 and arranged along the ground contact surface 2S has the fiber 10 oriented in a specific direction. Since it is not biased, the edge effect of the fiber 10 can be exhibited in all directions.

  FIG. 3 shows a plan view of the fiber chip 9 of the present embodiment. As shown in FIG. 3, the fibers 10 of the fiber chip 9 include, for example, a plurality of first fibers 10a arranged in a certain direction and a plurality of second fibers arranged in a direction crossing the first fibers 10a. 10b. Thereby, the fiber chip 9 forms a square mesh. The first fibers 10a and the second fibers 10b as described above can exhibit the edge effect in a balanced manner, and as a result, the on-ice performance and the wet performance can be further improved.

  In FIG. 3, the first fibers 10a and the second fibers 10b are orthogonal to each other, but the present invention is not limited to such an embodiment. In addition, the “rectangular mesh” is not limited to a strict regular tetragonal mesh as long as it is configured to have approximately four sides. In order to exhibit the edge effect in a well-balanced manner, the shape of the mesh may be, for example, a polygonal shape that is a pentagon or more, a circular shape, or the like in addition to the quadrangular shape.

  The first fiber 10a and the second fiber 10b are desirably woven and / or bonded, for example. In a more preferred embodiment, the first fiber 10a and the second fiber 10b are welded by heat, for example. In such a fiber chip 9, the intersection of the first fiber 10a and the second fiber 10b is flattened, and for example, damage starting from the intersection is suppressed.

  The size of the fiber chip 9 is not particularly limited, but if it is too large, the bonding strength with the rubber tends to decrease, and conversely if too small, the edge effect by the fiber 10 may not be sufficiently exhibited. From such a viewpoint, it is desirable that the fiber chip 9 has a rectangular shape with a side length L1 of 5 to 15 mm, for example. As another embodiment, the fiber chip 9 may be circular or elliptical with a maximum diameter of 5 to 15 mm (not shown).

  The mesh size of the fiber chip 9 is not particularly limited. In order to exhibit the efficient edge effect of the fiber 10 while maintaining good contact of the rubber part 8 of the tread rubber 7, the mesh diagonal L2 is preferably in the range of 1.5 to 3.5 mm. Is done.

  For the fibers 10 of the fiber chip 9, for example, synthetic fibers such as nylon, rayon and polyester, or natural fibers such as cotton and hemp are used.

  The fineness of the fiber 10 of the fiber chip 9 is not particularly limited, but is, for example, in the range of 900 to 2100 dtex in order to exhibit a sufficient edge effect while maintaining good adhesion with the rubber portion 8. Is desirable.

  The total mass of the fibers 10 with respect to the rubber portion 8 of the tread rubber 7 is not particularly limited. In order to fully exhibit the edge effect while maintaining the wear resistance and crack resistance of the tread rubber 7, the total mass of the fibers 10 of the tread rubber 7 is in the range of 5 to 15% of the mass of the rubber component. Is desirable.

  The tire 1 according to the present embodiment is easily manufactured by forming a raw tire containing unvulcanized tread rubber and vulcanizing it. For the unvulcanized tread rubber used in the green tire, a rubber composition in which at least the fiber chip 9 is blended with a rubber polymer may be used. This rubber composition is extruded, for example, as a flat tread rubber from an extruder or the like, and is incorporated into a green tire.

  In the tread rubber extrusion process, many fiber chips 9 can take a less resistance orientation in the flow of plasticized rubber. Therefore, the planar direction of many fiber chips 9 is along the direction of rubber flow, and that direction is preferable along the ground contact surface of the tread rubber.

  When the rigidity of the fiber chip 9 is small, there is a possibility that the mesh shape of the fiber is destroyed when kneaded with a rubber polymer by a mixer or an extruder. In such a case, as shown in FIG. 4, the fiber chip 9 and the rubber piece 24 are provided in advance as a fiber chip composite 23. The rubber piece 24 is formed in a sheet shape, for example, and is in a state in which vulcanization has progressed more than the rubber polymer constituting the rubber composition. Preferably, the rubber piece 24 is in a semi-vulcanized state that has not reached full vulcanization. Thereby, the rubber piece 24 can have a certain degree of rigidity, and as a result, it helps to maintain the shape of the fiber chip 9 fixed to one surface thereof.

  In the fiber chip composite 23, since the fiber chip 9 is reinforced with a rubber piece 24 having a certain degree of rigidity, the fiber 10 is also used when kneaded with a rubber polymer by a mixer or an extruder, or when extruded. There is no risk of the mesh shape being destroyed. FIG. 5 shows a right half sectional view of the unvulcanized tread rubber 7 ′. As is apparent from FIG. 5, the fiber chip composite 23 can be oriented along the ground contact surface 2S of the tread rubber 7 ′ while maintaining its shape.

  Further, since the rubber piece 24 is not completely vulcanized, good adhesion to the rubber polymer 25 can be obtained at the time of vulcanization molding of the raw tire in the mold. In a particularly preferred embodiment, the rubber piece 24 of the fiber chip composite 23 desirably contains the same rubber polymer as the rubber polymer 25 constituting the rubber portion 8 (shown in FIG. 2) of the tread rubber 7. In addition, the thickness etc. of the rubber piece 24 should just be determined so that the above-mentioned effect may be exhibited.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention can be changed into various aspects, without being limited to said specific embodiment, and can be implemented.

A tire of size 11R22.5 with tread rubber containing fiber chips was prototyped and tested according to the specifications in Table 1. Note that the tire of Comparative Example 1 does not include fiber chips in the tread rubber. The tire of Comparative Example 2 has a tread rubber containing short fibers oriented in the same direction during extrusion molding.
The common specifications and test methods for each sample tire are as follows.
Rim size: 22.5 × 9.00
Air pressure: 850kPa

<Performance on ice>
Each sample tire was mounted on all wheels of a 2-D vehicle (a 10-ton truck loaded halfway ahead), and the vehicle was driven on a test course including a road surface on ice by a test driver. The driving characteristics related to steering wheel response, rigidity, grip, etc. were evaluated by the driver's sensuality. Evaluation is shown by the score which sets the comparative example 1 to 100, and it is excellent in performance on ice, so that a numerical value is large.

<Wet performance>
On the wet asphalt road surface provided with a 5 mm water film, the vehicle was driven at 2nd speed and 1500 rpm, and the time from the moment when the clutch was engaged until it passed the 10 m point was measured. The evaluation is the reciprocal of the measured time, and is indicated by an index with Comparative Example 1 as 100. The larger the value, the better the wet performance.

<Uneven wear resistance>
After the vehicle traveled 10,000 km on the test course, the height of the block before and after the circumferential direction was measured, and the difference between the height of the block before and after the circumferential direction was calculated. The evaluation is the reciprocal of the calculated difference, and is indicated by an index with Comparative Example 1 being 100. The larger the value, the better the uneven wear resistance.

  As a result of the test, it can be confirmed that the on-ice performance and the wet performance of the tire of the example are improved as compared with the comparative example.

2 Tread portion 2S Grounding surface 7 Tread rubber 7 'Unvulcanized tread rubber 8 Rubber portion 9 Fiber chip 10 Fiber 23 Fiber chip composite 24 Rubber piece

Claims (9)

A pneumatic tire having a tread rubber,
The tread rubber is seen containing a plurality of fibers chips fibers are arranged in a net,
The total mass of the fibers of the tread rubber is in the range of 5 to 15% of the mass of the rubber component .
  The pneumatic tire according to claim 1, wherein the fiber chip includes one disposed along a ground contact surface of the tread rubber.   The pneumatic tire according to claim 1 or 2, wherein the fiber chip has a rectangular shape with a side of 5 to 15 mm.   The pneumatic tire according to claim 1 or 2, wherein the fiber chip has a circular shape or an elliptical shape having a maximum diameter of 5 to 15 mm. The pneumatic tire according to any one of claims 1 to 4, wherein the fiber chip includes one that is not exposed on a ground contact surface of the tread rubber .   The pneumatic tire according to claim 1, wherein the fiber is a natural fiber or a synthetic fiber.   The pneumatic tire according to claim 1, wherein the fibers have a fineness of 900 to 2100 dtex. A pneumatic tire manufacturing method comprising:
Including a step of forming a green tire containing unvulcanized tread rubber,
A rubber composition obtained by mixing the tread rubber with a rubber polymer and a fiber chip composite in which at least a fiber chip in which fibers are arranged in a net shape and a rubber piece that has been vulcanized more than the rubber polymer are integrated. A method for producing a pneumatic tire, characterized by using and molding.   The method for manufacturing a pneumatic tire according to claim 8, wherein the rubber piece of the fiber chip composite is in a semi-vulcanized state.

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