JP4448361B2 - Pneumatic radial tire and tire manufacturing method - Google Patents

Description

  The present invention relates to a pneumatic radial tire excellent in durability and strength and a method for manufacturing the tire.

  Conventionally, as a band layer of a pneumatic radial tire, a so-called jointless band formed by spirally winding a small belt-like ply covered with an organic fiber cord with a topping rubber around the belt layer is known. ing. However, with the recent development of highway networks, high output of vehicles, etc., further improvement in high-speed durability is desired.

  On the other hand, in order to reinforce a tire, for example, the following Patent Document 1 proposes to wrap a rubber strip in which short fibers are mixed in rubber around a tire constituent member. However, the rubber strip of Patent Document 1 is composed only of rubber blended with short fibers. A rubber compounded with short fibers has a defect that it is inferior in crack resistance and adhesiveness to other rubber materials.

JP 2001-287282 A

  The present invention has been devised in view of the above circumstances, and in the invention according to claim 1, a band-like ply forming a band layer is arranged on one surface and short fibers are blended. A pneumatic radial that can further improve the high-speed durability based on the first rubber material and the second rubber material that does not include the short fiber disposed on the other surface of the belt-like ply. The purpose is to provide tires.

  In the invention according to claim 4, the first rubber material containing the short fibers and the second rubber material not containing the short fibers are separately extruded and laminated to form an integral composite rubber. Providing a tire manufacturing method useful for manufacturing tires reinforced with high productivity on the basis of including a step of forming an annular tire rubber member by discharging the strip as a strip and winding the composite rubber strip. The purpose is to do.

  The invention according to claim 1 of the present invention is a pneumatic radial tire having a band layer outside a belt layer, wherein the band layer is a band in which one band cord or a plurality of band cords are arranged in parallel. It is formed by spirally winding a belt-like ply with a cord array covered with a topping rubber around the belt layer, and the topping rubber is disposed on one surface of the belt-like ply and is a short fiber. And a second rubber material that does not include short fibers disposed on the other surface of the belt-like ply.

  The invention according to claim 2 is characterized in that the band layer is wound with the one surface on which the first rubber material is disposed facing the belt layer side. This is a radial tire.

  According to a third aspect of the present invention, in the pneumatic layer according to the first aspect, the band layer is wound with the one surface on which the first rubber material is disposed facing the tread surface side. It is a radial tire.

The invention according to claim 4, comprising the steps of extruding a first rubber material short fiber is blended, and extruding the second rubber material short fiber is not blended, wherein the extruded separately A discharge step of laminating one rubber material and a second rubber material and discharging them as an integral composite rubber strip; and a molding step of forming the annular tire rubber member by winding the discharged composite rubber strip. Thus, the discharging step is a tire manufacturing method characterized by discharging the first and second rubber materials as plies by topping the tire cord array .

The invention described in claim 5, wherein the molding step is a process for the preparation of a tire according to claim 4, characterized in that it comprises a pre-Symbol step of spirally wound plies on the outside of the belt layer.

  In the pneumatic radial tire according to the first aspect of the present invention, the first rubber material in which short fibers are blended is disposed on one surface of the belt-like ply forming the band layer. Therefore, the strength of the belt-like ply is improved and the lifting of the belt layer can be further suppressed. In addition, since the second rubber material in which the short fiber is not blended is arranged on the other side of the belt-like ply, it is possible to prevent a significant decrease in the adhesiveness between the belt-like ply and other rubber members and to improve durability. It will be advantageous.

  In the tire manufacturing method according to claim 4, the first rubber material containing short fibers and the second rubber material not containing short fibers are respectively extruded and used as an integral composite rubber strip. The composite rubber strip is wound and the annular rubber member for tire is formed. In such a composite rubber strip, since the first rubber material in which short fibers are compounded on one side is compounded, the elastic modulus along the extrusion direction is improved and the tire is suitably reinforced. Can do. Moreover, since the second rubber material containing no short fibers is blended on the other side of the composite rubber strip, it is possible to prevent the crack resistance from deteriorating and to adhere to other rubber members. Deterioration can be prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a tire meridian cross-sectional view including a tire shaft of a pneumatic tire 1 of the present embodiment. The pneumatic tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2. A band layer 9 is provided on the outer side of the belt layer 7 in the tire radial direction. In this example, a radial tire 1 for a passenger car is illustrated.

  The carcass 6 is composed of one or more radial structures in which carcass cords are arranged at an angle of, for example, 80 ° to 90 ° with respect to the tire equator C, in this example, one carcass ply 6A. As the carcass cord, for example, an organic fiber cord such as polyester, nylon, rayon, aramid, or a steel cord is used if necessary.

  The carcass ply 6A is folded back from the inner side to the outer side in the tire axial direction around the bead core 5 extending from the main body part 6a and extending from the main body part 6a to the bead core 5 of the bead part 4 through the sidewall part 3 and the bead part 4. And the folded portion 6b. A bead apex 8 made of hard rubber extending from the bead core 5 to the outside in the tire radial direction is disposed between the main body portion 6a and the turn-up portion 6b of the carcass ply 6A, and the bead portion 4 is appropriately reinforced.

  Further, on the outside of the carcass 6, a tread rubber Tg that forms a ground contact surface, a side wall rubber Sg that forms an outer surface of the side wall portion, a bead rubber Ag that forms an outer surface of the bead portion 4, a clinch rubber rg that contacts the rim seat surface, and the tread rubber A cushion rubber Cg or the like disposed between Tg and the sidewall rubber Sg is disposed.

  The belt layer 7 includes at least two belt plies 7A in which steel cords are arranged as belt cords with an inclination of a small angle of, for example, 20 to 40 ° with respect to the tire equator C. , 7B are superposed in the direction in which the cords cross each other.

  In the present example, as shown in FIG. 2A, the band layer 9 has at least the same width as the belt layer 7 and a so-called full band disposed over the entire outer surface of the tire radial direction is exemplified. The The mode of the band layer 9 includes various modifications such as a full band, a so-called edge band that covers only both end portions of the belt layer 7, a crown band that covers only the center portion, and a combination of these. It is.

  As shown in FIG. 3, the band layer 9 of this embodiment is composed of a small band-shaped ply 9A in which a band cord array 10 in which a plurality of band cords 10a. . For example, the number is preferably 2 to 10, more preferably about 5 to 10, and the width of the strip ply 9A is preferably about 3 to 20 mm. As the band cord 10a, an organic fiber cord is preferable, and for example, nylon, rayon, polyethylene 2, 6 naphthalate or the like is desirable, and at least a cord material having lower elasticity than the belt cord constituting the belt layer 7 is used. The band-like ply 9A may have a so-called string shape in which only one band cord 10a is covered with the topping rubber 11, for example, in addition to a mode including a plurality of band cords 10a.

  The topping rubber 11 includes a first rubber material R1 disposed on one surface of the belt-like ply 9A and blended with short fibers f, and a short fiber f disposed on the other surface of the belt-like ply 9A. The second rubber material R2 is not included. The first rubber material R1 is extruded in the longitudinal direction of the belt-like ply 9A in the manufacturing process. At this time, 90% or more of the short fibers f blended in the rubber are oriented in the direction in which the flow resistance during extrusion becomes the smallest, that is, the major axis direction in the rubber extrusion direction. Thus, the first rubber material R1 is given orthogonal anisotropy with respect to the elastic modulus. That is, a reinforcing effect is provided in which the elastic modulus in the longitudinal direction of the belt-like ply 9A is larger than the elastic modulus in the direction perpendicular thereto. In this example, the thickness t1 of the first rubber material R1 and the thickness t2 of the second rubber material R2 are set to substantially the same thickness, but these may be changed as appropriate. it can.

  The belt-like ply 9A is spirally wound around the outer side of the belt layer 7 in the tire radial direction. Such spiral winding makes the angle of the band cord 10a with respect to the circumferential direction of the finished tire 5 ° or less. This is because when the angle is larger than 5 °, the restraining force of the band cord 10a on the belt layer 7 is reduced. 2A shows an example in which the belt-like ply 9A is wound so that the side edges overlap with the belt-like ply 9A adjacent in the tire axial direction. Thereby, the band cord 10a can be formed in two layers, excluding both ends. The winding method is not particularly limited. That is, the band cord 10a may be wound substantially so that the side edges of the belt-like ply 9A are in contact with each other, and the belt cord 10a may be wound with a gap provided between the side edges of the belt-like plies 9A, 9A.

  Further, by winding the belt-like ply 9A in a spiral shape, the short fibers blended in the first rubber material R1 also form an angle of about 5 ° or less with respect to the tire circumferential direction. Such a band layer 9 is provided with a band cord 10a extending substantially along the tire circumferential direction and a short fiber f blended with the first rubber material R1 to lift the belt layer 7 during high-speed running. It can be effectively suppressed to improve high-speed durability. In particular, the short fiber f can suppress the increase in tire weight remarkably smaller than the case of reinforcing by increasing the ply. In addition, since the rigidity (elastic modulus) of the belt-like ply 9A does not substantially change in the thickness direction, the impact mitigation ability is not lowered, and the riding comfort during normal running does not deteriorate. .

  In the first rubber material R1, for example, the short fiber f is desirably 2 to 40 parts by weight, more preferably 2 to 28 parts by weight with respect to 100 parts by weight of the rubber polymer. If the short fiber F is less than 2 parts by weight, the effect of increasing the restraining force on the belt layer 7 tends to be reduced, whereas if it exceeds 40 parts by weight, the crack resistance tends to be reduced. Particularly preferably, it is 10 parts by weight or more and 30 parts by weight or less.

  As the rubber polymer and / or the rubber polymer of the second rubber material R2, for example, a diene rubber is preferable, and more specifically, natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, and the like. One or two or more of these can be blended and used.

  Further, the short fibers f are preferably non-metallic with excellent adhesion to rubber. Specific examples include organic substances such as nylon, polyester, aramid, rayon, vinylon, aromatic polyamide, cotton, cellulose resin, and crystalline polybutadiene, and inorganic substances such as boron, glass fiber, and carbon fiber. These may be used alone or in combination of two or more. In addition, it is desirable that the short fiber is appropriately subjected to a surface treatment or the like in order to improve the adhesion to the rubber polymer.

  In addition, it is desirable that the short fibers f have, for example, an average fiber diameter of 1 to 100 μm and an average length of 0.1 to 5 mm. When the average fiber diameter is less than 1 μm or the length is less than 0.1 mm, the effect of improving the elastic modulus in the longitudinal direction of the topping rubber by the short fiber itself is lowered, and conversely, the average fiber diameter is larger than 100 μm. Alternatively, if the average length is greater than 5 mm, the short fibers F become too large, the adhesion to rubber is lowered, and the wear resistance and crack resistance are lowered. From this viewpoint, it is particularly desirable that the average fiber diameter of the short fibers is 3 to 50 μm and the length is 0.1 to 3 mm.

  The band layer 9 </ b> A of the present embodiment shows a mode in which one surface of the belt-like ply 9 </ b> A on which the first rubber material R <b> 1 is disposed is wound toward the belt layer 7 side. That is, the first rubber material R1 is bonded to the belt layer 7. Such an aspect has an advantage that the restraining effect can be more directly transmitted to the belt layer 7 by bringing the first rubber material R1 having a large tire circumferential rigidity closer to the belt layer 7.

  On the other hand, the band layer 9 of the aspect shown in FIG. 2B is wound with the one surface on which the first rubber material R1 is disposed facing the tread surface side. In other words, the second rubber material R2 in which the short fibers f are not blended is bonded to the belt layer 7. In such a mode, the shearing force generated between the band cord 10a and the belt cord during high-speed running is more effectively relaxed and absorbed by the second rubber material R2 having a relatively small elastic modulus in the tire circumferential direction. There is an advantage that it can. Further, since the second rubber material R2 having more adhesiveness is bonded to the belt layer 7, it is advantageous in terms of durability.

Also, in FIG. 4, a tire rubber member is a composite rubber in which a first rubber material R1 in which short fibers f are blended and a second rubber material R2 in which short fibers f are not blended are laminated and integrated. A strip 13 is shown . Examples of the tire rubber member include at least one selected from bead apex 8, tread rubber Tg, sidewall rubber Sg, bead rubber Ag, clinch rubber rg, and cushion rubber Cg. The composite rubber strip 13 may be considered as having no band cord 10a of the belt-like ply 9A.

  FIG. 5 shows an example of a strip forming apparatus 15 for manufacturing the composite rubber strip 13. The strip forming apparatus 15 includes a first extruder 21 for extruding the first rubber material R1 blended with the short fibers f, and a second extrusion for extruding the second rubber material R2 not blended with the short fibers f. In this embodiment, the first and second extruders 21 and 22 are arranged vertically on the base 16. The front end portions (end portions on the downstream side in the extrusion direction) of the first and second extruders 21 and 22 are connected to the connection head 23.

  The first and second extruders 21 and 22 have screw shafts SC1 and SC2 that are rotationally driven by electric motors M1 and M2, respectively. The unvulcanized raw rubber charged from the rubber inlet I is kneaded by the screw shaft SC1 or SC2 and extruded separately to the connecting head 23 side (extrusion step).

  As shown in FIG. 5 and FIG. 6 which is a partially enlarged view of the connection head 23, the connection head 23 includes a first discharge passage O1 through which the first rubber material R1 flows and a second flow through the second rubber material R2. A discharge flow path O2 is provided. The flow paths O1 and O2 are joined together for the first time by a preformer 29 provided at the tip of the connection head 23. Moreover, in the one rubber discharge flow path 34 in which the first rubber material R1 and the second rubber material flow together as R2, the first rubber material R1 and the second rubber material extruded separately from each other. In this example, R2 is laminated on top and bottom and extruded. By substantially equalizing the extrusion speeds of the first and second rubber materials R1 and R2, the first and second rubber materials R1 and R2 are naturally mixed together in the rubber discharge channel 34. Rather, as shown in FIG. 6, the two rubber materials R1 and R2 flow in a state having a substantially boundary surface.

  The rubber discharge channel 34 is connected to a die plate 31 provided on the downstream side in the extrusion direction. The die plate 31 can accurately determine the cross-sectional shape at the time of extruding the combined first and second rubber materials R1 and R2 and discharge it to the outside (discharge process). In this embodiment, the composite rubber strip 13 discharged from the discharge port of the die plate 31 passes between the pair of calendar rolls 25 and 26. Thereby, the thickness accuracy can be improved better. The calendar rolls 25 and 26 are rotatably supported on the base 32, and the gaps and the like can be appropriately adjusted as necessary.

  As shown in FIG. 7, as the discharging step, the first and second rubber materials R <b> 1 and R <b> 2 can be topped on an array of tire cords, for example, the band cord array 10. In this case, for example, the baffle 40 is disposed on the upstream side of the pre-former 29, and the cord array 10 is fed in an aligned state through the baffle 40, whereby the first rubber material is provided on one surface side thereof. R1 is configured such that the second rubber material R2 can be topped on the other surface side. Thereby, the belt-like ply 9A as shown in FIG. 3 can be manufactured.

  The composite rubber strip 13 discharged from the strip forming device 15 is formed as a tire rubber member by a method as shown in FIG. 8, for example. For example, FIG. 8A shows a case where the tread rubber Tg is molded using the composite rubber strip 13.

  The composite rubber strip 13 is wound around, for example, the outside of the band layer of the toroidal raw cover base 38 supported by the molding drum 37. That is, one end of the composite rubber strip 13 is fixed to the tread region of the raw cover base 37 and the molding drum 37 is rotated by the electric motor 40. Thereby, the raw cover base 37 rotates around the tire rotation axis, and the continuously supplied composite rubber strip 13 is sequentially wound around the tire in the tread region. The cross-sectional shape of the tread rubber Tg can be adjusted while changing the position of the composite rubber strip 13 with respect to the raw cover base 37 by moving either the molding drum 37 or the composite rubber strip 13 or both.

  FIG. 9 shows an example of the cross-sectional shape of the tread rubber Tg formed in this way. As a result, a substantially seamless tread rubber Tg can be formed. In the tread rubber, the first rubber material R1 in which the short fibers f are blended and the second rubber material R2 in which the short fibers are not blended are layered and laminated. The tread rubber Tg (rubber member for tire) of the present embodiment includes the first rubber material R1 in which the short fibers f are blended, so that the steering stability is improved as a result of increasing the elastic modulus in the tire circumferential direction.

  In addition, since the second rubber material R2 containing no short fibers is contained between the first rubber material R1 forming the layer, the adhesiveness, particularly crack resistance can be improved, and the origin of damage is generated. It is useful for suppressing over a long period of time. Further, while using two types of rubber materials, the two types of rubber materials R1 and R2 can be arranged at the same time by one winding, so there is no possibility of deteriorating productivity. For example, the second rubber material R2 having good adhesiveness is wound around the raw cover base 37 to help improve crack resistance.

  FIG. 8B shows an example in which the side wall rubber Sg is formed using the composite rubber strip 13. In this aspect, one end of the composite rubber strip 13 is fastened to the sidewall region of the raw cover base 37, and the composite rubber strip 13 is wound in a spiral shape to form the sidewall rubber Sg with a predetermined cross-sectional shape. it can.

The pneumatic radial tire (185 / 60R14) for passenger cars having the basic structure shown in FIG. 1 was tested for handling stability, high speed durability, and riding comfort, and the performance was compared. Each tire is different in only the topping rubber of the belt-like ply that forms the band layer, and the others are as shown in FIG. The composition of the topping rubber and the short fibers are as follows.
<Short fiber>
Material: Aramid Average diameter: 20μm
Average length: 0.5mm
Topping rubber composition (unit: parts by weight)
SBR 103
BR 26
Carbon 34
Oil 30
Sulfur 2.5
Vulcanization accelerator 2.5
Others (stearic acid, zinc white, etc.) 3.3

(Comparative Example 1)
A belt-shaped ply topping rubber made of a rubber material that does not contain short fibers.
(Comparative Example 2)
The topping rubber of the belt-like ply consists only of rubber material containing short fibers.
Example 1
The band layer has the structure of FIG.
(Example 2)
The band layer has the structure of FIG.
(Example 3)
The band layer has the structure shown in FIG.
The contents of the test are as follows.

<Steering stability>
Each test tire is mounted on 4 wheels of a domestic FF vehicle with a displacement of 2000 cm ³ (rim: 14 x 5.5 J, internal pressure 200 kPa), drive on a dry asphalt road test course with one driver, and handle response The driver's sensory evaluation evaluated the overall handling stability in terms of performance, rigidity, and grip. The results were evaluated by a 10-point method with Comparative Example 1 as 6. The larger the value, the better.

<High speed durability>
The rim was assembled on a rim (14 × 5.5 J) and filled with an internal pressure of 280 kPa, and a step speed method was performed in accordance with a load / speed performance test defined by ECE30 using a drum tester. The test increased the running speed sequentially and measured the speed and time when the tire broke down.

<Ride comfort>
In the same vehicle as the steering stability test, perform sensory evaluation on ruggedness, push-up, dumping on stepped road on dry asphalt road, Berjaso road (cobblestone road), Bitzmann road (road surface covered with pebbles), etc. Evaluation was carried out by a 10-point method with Comparative Example 1 as 6. The larger the value, the better.
Table 1 shows the test results.

  As a result of the test, it can be confirmed that all of the tires of the examples have improved steering stability and high-speed durability. It can also be seen that there is no difference in ride comfort.

  Next, a pneumatic tire using a composite rubber strip as a sidewall rubber was prototyped based on the specifications shown in FIG. 1 and tested in the same manner as described above. The band layer structure was the same as in Example 1. Table 2 shows the test results.

  As a result of the test, it can be confirmed that the tires of the examples all have improved durability. It can also be seen that there is no difference in ride comfort.

It is sectional drawing of the pneumatic radial tire of this embodiment. (A), (B) is sectional drawing of the belt layer and a band layer. It is a fragmentary perspective view of a strip ply. It is a perspective view of a composite rubber strip. It is a front view which shows an example of the shaping | molding apparatus which shape | molds a composite rubber strip. It is the principal part expanded sectional view. It is sectional drawing explaining the method to shape | mold a strip | ply. (A), (B) is a fragmentary perspective view which illustrates the manufacturing method of the rubber member for tires. It is sectional drawing which shows an example of a tread rubber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 9 Band layer 9A Band-like ply 10 Band cord arrangement body 10a Band cord 11 Topping rubber R1 First rubber material R2 Second rubber material 13 Composite rubber strip Tg Tread rubber Sg Side wall rubber f Short fiber

Claims (5)

A pneumatic radial tire having a band layer outside the belt layer,
The band layer is formed by spirally winding a small band-shaped ply in which a band cord array in which one band cord or a plurality of band cords are arranged in parallel is covered with a topping rubber around the belt layer. With
The topping rubber includes a first rubber material arranged on one surface of the belt-like ply and blended with short fibers, and a second rubber not containing the short fibers arranged on the other surface of the belt-like ply. A pneumatic radial tire characterized by comprising a material.   2. The pneumatic radial tire according to claim 1, wherein the band layer is wound with a surface on one side on which the first rubber material is disposed facing the belt layer side.   2. The pneumatic radial tire according to claim 1, wherein the band layer is wound with a first surface on which the first rubber material is disposed facing a tread surface side. 3. A step of extruding a first rubber material containing short fibers;
A step of extruding a second rubber material containing no short fibers;
A discharge step in which the first rubber material and the second rubber material extruded separately are stacked and discharged as an integral composite rubber strip;
Look including a molding step of winding said discharge composite rubber strip forming the rubber member for an annular tire,
The method for manufacturing a tire is characterized in that in the discharging step, the first and second rubber materials are topped on an array of tire cords and discharged as a ply . It said forming step is the tire manufacturing method of claim 4, wherein the containing pre Symbol step of spirally wound plies on the outside of the belt layer.

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