JP2009035029A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide, especially, a passenger car radial tire, which takes an advantage of a high-modulus cover material, in which high speed durability is improved. <P>SOLUTION: A pneumatic tire has at least two cross belt layers 6 outside in the radial direction of a carcass layer 4 of a tread 1, and a circumferential belt auxiliary reinforcing layer formed by spirally winding a strip member in the circumference in which one or a plurality of organic fiber codes are doubled outside in the radial direction of the cross belt layer 6. The circumferential belt auxiliary reinforcing layer comprises a full cover layer 7 and a shoulder cover layer 8. (A) The full cover layer 7 is at least arranged in the entire area of the belt layer, and is a low-modulus organic fiber comprising a low-modulus fiber with an elasticity modulus of lower than 10,000 MPa. (B) The shoulder cover layer 8 is arranged inside in a width direction rather than the end of the narrowest-width-belt layer and at both shoulders, and is a belt auxiliary reinforcing layer comprising a high-modulus organic fiber code with an elasticity modulus of 10,000 MPa or higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

  More specifically, the present invention relates to a pneumatic tire that is optimal as a radial tire for a passenger car in which a cover layer having improved high-speed durability is provided while efficiently reducing road noise.

  The effects expected of a highly elastic belt cover material for passenger car tires include improved high-speed durability and road noise countermeasures.

  In particular, it has been found that it is effective to dispose a hybrid cover material on the tire shoulder for reducing road noise, and related proposals have been made.

  For example, a full band ply in which a first band cord made of a low-elasticity organic fiber cord is arranged substantially in parallel to the tire equator, and only both side edge portions of the belt layer are covered. In addition, a proposal has been made on a pneumatic radial tire including an edge band ply in which a second band cord made of a highly elastic organic fiber cord is paired (Patent Document 1).

  However, a tire having a high elastic belt cover disposed on both side edges of the belt layer has a characteristic that the belt edge tends to extend in the tire circumferential direction at the tire ground contact portion. Because it is difficult to stretch in the tire circumferential direction due to the characteristics, it spreads in the belt width direction (extends in the width direction) so as to gain a ground contact area, and as a result, between the highly elastic cover cord and the edge of the belt. The phenomenon that the shear strain increases occurs, and as a result, there is a problem that separation (peeling) occurs between the first belt edge and the belt cover layer. This separation (peeling) that occurs between the belt edge and the belt cover layer is a characteristic of pneumatic tires with a highly elastic belt cover layer. This separation occurs relatively early, and is improved. Was desired.

After all, it can be said that tires with high-elasticity belt covers on both side edges of the belt layer are in the direction of increasing durability because the high-elasticity cover suppresses the progress of separation. As a result, the fatigue of the cover cord is induced, which causes a new problem particularly in terms of high-speed durability, and the actual situation is that the advantages of the high-elasticity cover are not fully utilized.
Japanese Patent No. 3113592

  An object of the present invention is a pneumatic tire using a high-elasticity cover material in view of the above-described points, and the high-speed durability is remarkably improved. An object of the present invention is to provide a pneumatic tire that is particularly suitable as a radial tire for passenger cars.

  The pneumatic tire of the present invention that achieves the above-described object has the following configuration (1).

(1) A belt-shaped member in which at least two cross belt layers are arranged on the outer side in the tire radial direction of the carcass layer of the tread portion, and one or a plurality of organic fiber cords are arranged on the outer side in the tire radial direction of the cross belt layer. In the pneumatic tire having a circumferential belt auxiliary reinforcing layer formed by spirally winding in the circumferential direction, the circumferential belt auxiliary reinforcing layer includes a full cover layer (A) below and a shoulder (B) below. A pneumatic tire comprising a cover layer.
(A) Full cover layer: a belt auxiliary reinforcing layer that is a low-elasticity organic fiber cord that is arranged so as to cover at least the entire belt layer and the organic fiber cord is twisted together with low-elasticity fibers having an elastic modulus of less than 10,000 MPa.
(B) Shoulder cover layer: a high-elasticity organic fiber cord having an elastic modulus of 10,000 MPa or more, which is disposed on the inner side in the tire width direction than the belt end portion of the narrowest belt layer and on both shoulder portions. A belt auxiliary reinforcement layer.

  In the pneumatic tire of the present invention, preferably, the pneumatic tire has a specific configuration described in any one of the following (2) to (7).

  (2) The high elastic organic fiber cord having an elastic modulus of 10,000 MPa or more constituting the shoulder cover layer is a composite organic fiber cord in which a high elastic organic fiber having an elastic modulus of 10,000 MPa or more and a low elastic fiber having an elastic modulus of less than 10,000 MPa are twisted together. The pneumatic tire as described in (1) above, wherein

  (3) The above (1) or (2), wherein an average distance between an outer end in the tire width direction of the shoulder cover layer and a belt end of the narrowest belt layer is 5 mm or more and 20 mm or less. The described pneumatic tire.

  (4) The width per one side of the shoulder cover layer is 10% or more and 25% or less of the width of the widest belt layer, according to any one of (1) to (3) above Pneumatic tire.

  (5) The outer end portions in the tire width direction of the full cover layer are outside the end portion of the widest belt layer, and the average distance from the end portion is 3 mm or more and 20 mm or less. The pneumatic tire according to any one of (1) to (4) above.

  (6) As the circumferential belt auxiliary reinforcing layer, 5% or more of the width of the widest belt layer made of the same material as the shoulder cover layer at the inner layer of the full cover layer and at the belt center portion. The pneumatic tire according to any one of (1) to (5) above, wherein a center cover layer that is 15% or less is disposed.

  (7) The pneumatic tire according to any one of (1) to (6), wherein the shoulder cover layer is disposed on the outer side in the tire radial direction of the full cover layer.

  According to the present invention, a pneumatic tire using a high-elasticity cover material is excellent in low road noise and has a significantly improved high-speed durability. A pneumatic tire that can be used in two minutes is provided.

  In particular, the pneumatic tire of the present invention is optimal as a pneumatic radial tire for passenger cars due to its excellent low road noise performance and high-speed durability performance.

  Hereinafter, the pneumatic tire of the present invention will be described in more detail based on the drawings and the like.

  FIG. 1 is a schematic cross-sectional view taken in the meridian direction of a pneumatic tire for explaining an example of an embodiment of the pneumatic tire of the present invention. The pneumatic tire of the present invention has a tread as shown in FIG. A belt-shaped member in which at least two cross belt layers 6 are arranged on the outer side in the tire radial direction of the carcass layer 4 of the portion 1 and one or more organic fiber cords are arranged on the outer side in the tire radial direction of the cross belt layer 6 is a tire. In the pneumatic tire having the circumferential belt auxiliary reinforcing layer formed by spirally winding in the circumferential direction, the circumferential belt auxiliary reinforcing layer includes the full cover layer 7 of the following (A) and the following (B). A pneumatic tire comprising a shoulder cover layer 8.

  (A) Full cover layer 7: A belt auxiliary reinforcing layer which is a low elastic organic fiber cord which is arranged so as to cover at least the entire belt layer and the organic fiber cord is twisted together with low elastic fibers having an elastic modulus of less than 10000 MPa. .

  (B) Shoulder cover layer 8: a high-elasticity organic fiber cord disposed on the inner side in the tire width direction and on both shoulders from the belt end of the narrowest belt layer, and the organic fiber cord has an elastic modulus of 10,000 MPa or more. The belt auxiliary reinforcement layer.

  In FIG. 1, 2 is a sidewall portion, 3 is a bead portion, and 5 is a bead core.

  FIG. 2 is a schematic cross-sectional view taken in the meridian direction of the pneumatic tire for explaining another example of the embodiment of the pneumatic tire of the present invention. FIG. 3 is a schematic model diagram showing an arrangement example of the belt layer and the belt auxiliary reinforcing layer in the embodiment shown in FIG. 1 in order to explain an example of the embodiment of the pneumatic tire of the present invention. FIG. 4 is a schematic model diagram showing an arrangement example of the belt layer and the belt auxiliary reinforcing layer in the other example shown in FIG. 2 in order to explain an example of the embodiment of the pneumatic tire of the present invention.

  Further, regarding the position of the shoulder cover layer 8, “inward in the tire width direction from the belt end of the narrowest belt layer” means that the shoulder cover is on the arrow A side shown in FIGS. 3 and 4. That is, the layer 8 is disposed.

  In the pneumatic tire of the present invention, the shoulder cover belt auxiliary reinforcing layer 8, which is a highly elastic organic fiber cord, is disposed more than the end in the tire width direction of the narrowest belt layer (generally, the second belt corresponds). By arranging the full cover belt auxiliary reinforcing layer 7 with low rigidity so as to be arranged on the inner side and to protrude outward in the tire width direction, the inclination of the rigidity of the belt edge portion is ensured, The shear strain between the No. 1 belt and the belt cover layer is relieved, and the occurrence of separation can be delayed. As a result, the tire durability performance can be improved by the amount of occurrence of the separation.

  That is, in the pneumatic tire of the present invention, firstly, the high elastic cover is disposed on the inner side in the tire width direction to reduce the rigidity step at the belt edge, and secondly, the higher height on the inner side in the width direction. The elastic cover suppresses the expansion of the tire diameter and delays the progress of the separation, thereby improving the high speed durability.

  In the present invention, typical low-elasticity organic fibers having an elastic modulus of less than 10,000 MPa constituting the full cover layer 7 include nylon 66 fibers and polyethylene terephthalate (PET) fibers.

  The organic fibers forming the highly elastic organic fiber cord having an elastic modulus of 10,000 MPa or more constituting the shoulder cover layer 8 include aramid fibers, polybenzoxazole (PBO) fibers, polyolefin ketone (POK) fibers, or polyethylene naphthalate (PEN). ) There are fibers.

  The cord constituting the shoulder cover layer 8 is preferably a composite organic fiber cord in which a high elastic organic fiber having an elastic modulus of 10,000 MPa or more and a low elastic fiber having an elastic modulus of less than 10,000 MPa are twisted together. Even in the case of the composite organic fiber cord, the highly elastic organic fiber having an elastic modulus of 10,000 MPa or more is preferably an aramid fiber, a polybenzoxazole (PBO) fiber, a polyolefin ketone (POK) fiber, or polyethylene naphthalate (PEN). ) Fiber etc. Typical examples of the low elastic fiber having an elastic modulus of less than 10,000 MPa include nylon 66 fiber and polyethylene terephthalate (PET) fiber.

  That is, in the pneumatic tire of the present invention, the high elastic organic fiber cord having an elastic modulus of 10,000 MPa or more constituting the shoulder cover layer 8 is twisted by the high elastic organic fiber having an elastic modulus of 10,000 MPa or more and the low elastic fiber having an elastic modulus of less than 10,000 MPa. It is preferably a composite organic fiber cord formed by combining them. When a cord having such a structure is adopted, durability is improved due to the presence of the highly elastic organic fiber, but a new shear strain is generated when the cord is used with the 100% highly elastic organic fiber. High durability can be achieved in a well-balanced manner without incurring the problem of peeling of the belt layer.

It 3, as shown in FIG. 4, the tire width direction outer end portion of the shoulder cover layer 8, the average distance D ₁ of the belt end portion of the most narrow belt layer is 5mm or more 20mm or less However, it is preferable for obtaining the desired effect of the present invention. The “belt of the belt layer having the narrowest width” here usually corresponds to the second belt in the case of two belt layers. The first belt refers to a belt layer located on the innermost side in the tire circumferential direction, and the next belt located on the outer circumferential side of the tire is the second belt, more preferably 8 mm or more and 15 mm or less.

  The width of one side of the shoulder cover layer 8 is preferably 10% to 25% of the width of the widest belt layer. The “belt of the widest belt layer” here is usually the above-mentioned No. 1 belt in the case of two belt layers, but is not concerned with the order of lamination itself. More preferably, it is 15% or more and 25% or less. If the width per side of the shoulder cover layer 8 is less than 10% of the width of the widest belt layer, the improvement effect is small, and if it exceeds 25%, the improvement effect is saturated.

The outer end portions in the tire width direction of the full cover layer 7 is outwardly than the end of the widest belt layer, and the average distance D ₂ is more than 3mm the ends of the widest belt layer It is preferable that it is 20 mm or less in order to achieve the desired effect of the present invention satisfactorily. A more preferable range of the average distance D ₂ is 5 mm or more and 15 mm or less.

  Although not shown in the drawings, preferably, as a circumferential belt auxiliary reinforcing layer, a belt having the widest width in the same material as the shoulder cover layer 8 at the inner layer of the full cover layer 7 and at the belt center portion. It is preferable to arrange a center cover layer that is 5% to 15% of the width of the layer. When the center cover layer is arranged in this manner, the antinode of the secondary deformation mode in the tire meridian section is suppressed, the medium frequency road noise is improved, and at the same time, the rising due to the high speed rotation is also suppressed. Thus, the durability is further improved.

  In the present invention, the shoulder cover layer 8 may be disposed on the outer side or the inner side of the full cover layer 7 in the tire radial direction, or may be disposed on both the outer side and the inner side. FIG. 1 and FIG. 3 show an example of an embodiment arranged outside, and FIG. 2 and FIG. 4 show an example of an embodiment arranged inside.

  Examples will be described below, and the specific configuration and effects of the pneumatic radial tire of the present invention will be further described.

  The elastic modulus used in the description of the present invention is measured by the following method.

(1) Elastic modulus of the cord:
A rubber-tired tire cord collected from the tire was subjected to a tensile test in accordance with JIS L1017-2002 “Chemical Fiber Tire Cord Test Method” to obtain an elastic modulus.

Specifically, the elastic modulus E was calculated by the following equation, where e ₁ (%) is the elongation of the cord at a load of 44 N and e ₂ (%) is the elongation of the cord at a load of 149 N.
E = [105 / (e ₂ −e ₁ ) × 100] / S
Here, S is a code cross-sectional area, the unit is mm ² , and S was obtained as follows.
S = D / 10000ρ
D: nominal fineness of fiber cord (dtex), ρ: specific gravity of fiber (nominal specific gravity)

  The time from cord collection to measurement shall be within 5 minutes.

  Further, the elastic modulus of the fiber (yarn) was also measured according to the above method.

(2) Tire durability test:
About a test tire inflated with a rim size of 17 x 7.5 JJ and a test internal pressure of 180 kPa, using a drum tester having a smooth drum surface and a diameter of 1707 mm, controlling the ambient temperature to 38 ± 3 ° C A load of 120% of the maximum load specified by JATMA is applied, and the vehicle is run at a speed of 120 km / hr for 2 hours. Next, the vehicle is run for 2 hours at 150 km / hr under the same load. Next, the vehicle was run at a speed of 150 km / hr for 30 minutes under the same load. Thereafter, the drum was run every 30 minutes until the tire was destroyed while stepping up the speed by 10 km / hr.

  The mileage is expressed as an index based on Conventional Example 1, and the larger the number, the better the durability.

  The destruction mode was judged by looking at the condition of the tire after destruction.

  The actual vehicle road noise / feeling evaluation was performed by attaching it to a passenger car and performing a feeling evaluation (sensory evaluation).

Examples 1-6, Conventional Examples 1-3
Various test tires having a tire size of 225 / 45R17 and a belt width (first belt width) of 200 mm were manufactured. The No. 2 belt width is 190 mm.

  As the highly elastic organic fiber cord (X) forming the circumferential belt auxiliary reinforcing layer (shoulder cover layer), an aramid fiber 1670 dtex / nylon 66 fiber 1400 dtex cord (the number of twists of the aramid fiber yarn is 38 t / 10 cm (Z direction)) Nylon 66 fiber yarn was used with a twist of 38 t / 10 cm (Z direction) and a twist of 38 t / 10 cm (S direction). The elastic modulus of the highly elastic organic fiber cord was 13000 MPa.

  The elastic modulus of the aramid fiber was 65000 MPa, and the elastic modulus of the nylon 66 fiber was 4000 MPa.

  As the low elastic organic fiber cord (Y) forming the circumferential belt auxiliary reinforcing layer (full cover layer), nylon 66 fiber 1400 dtex / 2 cord (the number of twists of two nylon 66 fiber yarns is 25 t / 10 cm (Z direction) ), An upper twist number of 25 t / 10 cm (S direction)). The elastic modulus of the low elastic organic fiber cord was 4000 MPa.

  In addition, in any of the circumferential belt auxiliary reinforcing layers, five cords are embedded in unvulcanized rubber to form a 5 mm wide belt-like member that is spirally wound at about 0 degrees with respect to the tire equatorial plane. Formed by turning.

  The structure of the auxiliary reinforcing layer employed in each example (1-6) and each conventional example (1-3) is as shown in the schematic diagrams in Tables 1 and 2.

  In Tables 1 and 2, the width ratio (%) of the shoulder cover auxiliary reinforcing layer indicates the width ratio on only one side. “-5 mm” of “No. 2 belt end to S auxiliary reinforcing layer distance” in Conventional Examples 1 and 2 is smaller than the end (edge portion) of the narrowest belt layer (No. 2 belt) in the present invention. A shoulder auxiliary reinforcing layer is provided so as to protrude in the tire width direction, and the distance between the front end of the shoulder auxiliary reinforcing layer in the width direction and the end of the second belt is 5 mm.

  Tables 1 and 2 show the results of evaluating the tire durability, the form of destruction of the tire, and the road noise performance in an actual vehicle in each of the examples (1 to 6) and the conventional examples (1 to 3).

  As shown in Table 1 and Table 2, it can be seen that the pneumatic tire according to the present invention has excellent performance at high speed durability while having good low road noise performance. .

FIG. 1 is a schematic cross-sectional view taken in the meridian direction of a pneumatic tire for explaining an example of an embodiment of the pneumatic tire of the present invention. FIG. 2 is a schematic cross-sectional view taken in the meridian direction of a pneumatic tire for explaining another example of the embodiment of the pneumatic tire of the present invention. FIG. 3 is a schematic model diagram showing an arrangement example of the belt layer and the belt auxiliary reinforcing layer in the embodiment shown in FIG. 1 in order to explain an example of the embodiment of the pneumatic tire of the present invention. FIG. 4 is a schematic model diagram showing an arrangement example of the belt layer and the belt auxiliary reinforcing layer in the other example shown in FIG. 2 in order to explain an example of the embodiment of the pneumatic tire of the present invention.

Explanation of symbols

1: Tread portion 2: Side wall portion 3: Bead portion 4: Carcass layer 5: Bead core 6: Cross belt layer 7: Full cover belt auxiliary reinforcing layer 8: Shoulder cover belt auxiliary reinforcing layer D ₁ : Tire of shoulder cover layer 8 Average distance D ₂ between the outer end in the width direction and the belt end of the narrowest belt layer: The average distance between the outer end in the tire width direction of the full cover layer 7 and the end of the widest belt layer

Claims (7)

At least two cross belt layers on the outer side in the tire radial direction of the carcass layer of the tread portion, and a belt-shaped member in which one or more organic fiber cords are aligned on the outer side in the tire radial direction of the cross belt layer in the tire circumferential direction. In the pneumatic tire having a circumferential belt auxiliary reinforcing layer configured by winding in a spiral shape, the circumferential belt auxiliary reinforcing layer includes a full cover layer (A) below and a shoulder cover layer (B) below. A pneumatic tire characterized by comprising:
(A) Full cover layer: a belt auxiliary reinforcing layer which is a low elastic organic fiber cord which is arranged so as to cover at least the entire belt layer and the organic fiber cord is twisted together with low elastic fibers having an elastic modulus of less than 10,000 MPa.
(B) Shoulder cover layer: a high-elasticity organic fiber cord having an elastic modulus of 10,000 MPa or more, which is disposed on the inner side in the tire width direction than the belt end portion of the narrowest belt layer and on both shoulder portions. A belt auxiliary reinforcement layer.   The high-elasticity organic fiber cord having an elastic modulus of 10,000 MPa or more constituting the shoulder cover layer is a composite organic fiber cord in which a high-elasticity organic fiber having an elastic modulus of 10,000 MPa or more and a low-elasticity fiber having an elastic modulus of less than 10,000 MPa are twisted together. The pneumatic tire according to claim 1.   3. The pneumatic tire according to claim 1, wherein an average distance between an outer end portion in the tire width direction of the shoulder cover layer and a belt end portion of the narrowest belt layer is 5 mm or more and 20 mm or less.   The pneumatic tire according to any one of claims 1 to 3, wherein a width per side of the shoulder cover layer is 10% or more and 25% or less of a width of the widest belt layer.   The outer end portions of the full cover layer in the tire width direction are outside the end portions of the widest belt layer, and the average distance from the end portions is 3 mm or more and 20 mm or less. Item 5. The pneumatic tire according to any one of Items 1 to 4.   As the circumferential belt auxiliary reinforcing layer, the inner layer of the full cover layer, and the belt center portion is made of the same material as the shoulder cover layer and has a width of 5% or more and 15% or less of the widest belt layer. The pneumatic tire according to claim 1, wherein a center cover layer is disposed.   The pneumatic tire according to any one of claims 1 to 6, wherein the shoulder cover layer is disposed on the outer side in the tire radial direction of the full cover layer.

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