JPH10217715A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for passenger cars, which is capable of improving to high speed durability while it is lightweight and the productivity in molding is increased. SOLUTION: With the tire, belt layers 5, 6 are provided on the outside periphery side of a carcass layer 2 in the tread part. In this case, the belt layers 5, 6 are structured as follows: a calender material 18 where plural organic fiber cords 16 are arranged in parallel, is spirally wound to obtain a tube 15, and the tube 19 is flattened to be formed into a tape 20 having a width of 5 to 20mm. The tape 20 meanders to be continuously wrapped in plural turns so that the maximum angle of inclination from the tire-circumferential direction falls in the range 5 to 25 degrees.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire for a passenger vehicle, and more particularly to a pneumatic radial tire for a passenger vehicle which is lightweight, improves molding productivity, and improves high-speed durability.

[0002]

2. Description of the Related Art Conventionally, a pneumatic radial tire for a passenger car has two belt layers in which both ends are bias-cut so that a plurality of steel cords are inclined at a relatively small angle with respect to the tire circumferential direction. It has a belt structure in which cords are arranged so as to cross each other between layers. However, in the above-mentioned belt structure, stress tends to concentrate on the cut end surfaces of both ends of the belt layer in the tire width direction, and the tire layer in the width direction of the belt layer tends to rise due to centrifugal force during high-speed running. However, there is a problem that separation easily occurs at the cut end face, and high-speed durability is poor.

[0003] For this reason, for a high-performance tire satisfying, for example, the HR standard or VR standard, a belt cover layer composed of a plurality of organic fiber cords extending substantially at 0 ° to the tire circumferential direction is provided with a reinforcing material. It was essential to add as. As a result, not only the tire weight increases, the rolling resistance increases, but also the tire molding productivity decreases with the increase in the number of members, leading to an increase in cost.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for a passenger car which is lightweight and capable of improving high-speed durability while increasing molding productivity.

[0005]

In order to achieve the above object, a pneumatic radial tire for a passenger car according to the present invention is provided with at least one belt layer on an outer peripheral side of a carcass layer in a tread portion. A calendar material in which a plurality of organic fiber cords are aligned in parallel is spirally wound into a tube, and the tube is flattened to a width of 5 to 2 mm.
The tape is formed into a 0 mm tape, and the tape is continuously wound a plurality of times while meandering such that the maximum inclination angle with respect to the tire circumferential direction is in a range of 5 ° to 25 °. .

[0006] As described above, the calender material composed of a plurality of organic fiber cords is spirally wound into a tube, the tube is flattened and formed into a tape having the above width, and the tape is meandered in the tire circumferential direction. By forming the belt layer by continuously winding it a plurality of times, it is possible to improve the high-speed durability while being lightweight and increase the molding productivity, and also to improve the uniformity.

That is, the above-mentioned belt layer is arranged such that the organic fiber cords are continuously folded back and forth in the tape, and there is substantially no cut end face at both ends in the tire width direction. Has extremely high rigidity. Therefore, it is possible to prevent the belt layer from rising at both ends in the tire width direction at the time of high-speed running, and it is possible to improve high-speed durability. In addition, since the tape constituting the belt layer is meandered so that the maximum inclination angle is in the above-mentioned range and the in-plane bending rigidity is increased, good steering stability can be ensured.

Further, according to the belt structure, for example, H
Since it is no longer necessary to add a belt cover layer made of an organic fiber cord to a high-performance tire satisfying the R standard and the VR standard, the weight of the tire can be reduced and the number of members can be reduced. Tire molding productivity can be improved. In addition, since the belt layer is formed by winding the tape continuously plural times while meandering in the tire circumferential direction, the splice portion (joining portion) unlike the conventional belt cover layer does not substantially exist. The uniformity of the tire becomes good.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 illustrate a pneumatic radial tire for a passenger car according to an embodiment of the present invention. In the figure, a carcass layer 2 is mounted between a pair of left and right bead portions 1, 1, and both end portions of the carcass layer 2 are turned around a bead core 3 from the inside of the tire to the outside.

Two belt layers 5, 6 are buried on the outer peripheral side of the carcass layer 2 in the tread portion 4. The belt layers 5 and 6 are formed by forming the tape 20 having a width of 5 to 20 mm shown in FIG.
The structure is such that it is continuously wound several times over the belt width while meandering in the range of °. As shown in FIG. 4A, a plurality of organic fiber cords 16 are aligned in parallel, and a belt-shaped calender material 18 coated with an unvulcanized rubber matrix 17 is spirally wound on the tape 20 as shown in FIG. The tube 19 is formed by flattening the tube 19 as shown in FIG.

In the tire configured as described above, the belt layers 5 and 6 are arranged such that the organic fiber cords 16 are continuously folded in a zigzag manner in the flattened tape 20, and both end portions in the tire width direction are arranged. Since the cut end face of the cord does not substantially exist, the rigidity in the tire circumferential direction is extremely high. Therefore, even at the time of high-speed running, it is possible to suppress the phenomenon of the belt layers 5 and 6 rising at both ends in the tire width direction, and it is possible to improve high-speed durability.

Further, the belt layers 5 and 6 are formed by continuously winding the tape 20 a plurality of times while meandering in the tire circumferential direction, so that a splice portion (joining portion) like a conventional belt cover layer is substantially formed. Since there is no stiffness, there is no difference in rigidity due to the splice,
The uniformity of the tire becomes good. The width of the tape 20 constituting the belt layers 5 and 6 is 5 to 20 mm. When the width of the tape 20 is less than 5 mm, the width is too small and the number of windings of the tape 20 increases, so that the productivity is reduced. Therefore, uniformity and durability are reduced. Further, the inclination angle of the organic fiber cord 16 with respect to the length direction of the tape 20 is 10 ° to
Preferably, it is 45 °.

The tape 20 is wound so as to meander in the tire circumferential direction. In the meandering of the tape 20, the inclination angle continuously changes in the tire circumferential direction,
It shall be wound so that the maximum inclination angle is in the range of 5 ° to 25 °. By meandering the tape 20 so that the maximum inclination angle is in the above range, the in-plane bending stiffness of the belt layers 5 and 6 can be secured, and good steering stability can be secured. When the maximum inclination angle of the tape 20 is less than 5 °, the in-plane bending stiffness of the belt layers 5 and 6 becomes insufficient, and when it exceeds 25 °, the rigidity in the tire circumferential direction becomes insufficient.

When two or more belt layers 5 and 6 are provided as described above, it is preferable that the meandering pitch of the tape 20 in the tire circumferential direction be shifted between the layers. By shifting the meandering pitch of the tape 20 in the tire circumferential direction between the layers, the rigidity in the tire width direction as a whole belt layer becomes uniform, so that the steering stability can be improved.

The organic fiber cords 16 of the belt layers 5 and 6 are
Use a twisted cord obtained by twisting at least one of organic fibers selected from the group consisting of polyester fibers, aromatic polyamide fibers, polyarylate fibers, polyparaphenylene benzobisoxazole fibers, polyvinyl alcohol fibers, rayon fibers, and nylon fibers. Is preferred.
Among them, as the polyester fiber, polyethylene terephthalate fiber and polyethylene 2,6-naphthalate fiber are particularly preferable, or extra high modulus polyester (EHM polyester) having an ultra-high modulus of elasticity is preferably used. These organic fibers have high rigidity and can be easily processed into the tape 20. The matrix 17 of the tape 20 is not limited to rubber, but may be a resin such as urethane resin.

According to the above-described belt structure, in a high-performance tire satisfying, for example, the HR standard or the VR standard, a plurality of organic fibers extending at substantially 0 ° with respect to the circumferential direction of the tire as in the prior art. Since it is not necessary to add a belt cover layer made of a cord, it is possible to reduce the weight of the tire and to improve the molding productivity of the tire by reducing the number of members.

When the tire as described above is manufactured, a tire material such as the carcass layer 2 is stuck on a forming drum,
By expanding the green tire from the inside to near the product size in the tire radial direction, the belt layers 5, 6 and tread rubber are bonded to form a green tire, and the green tire is inserted into a mold and vulcanized. It is possible to mold a tread pattern on the tread portion 4.

However, the belt structure of the present invention has a strong restraining force in the tire circumferential direction, and it is difficult to lift the belt during the tire vulcanization. Therefore, it is necessary to use a vulcanization molding method that does not require a belt lift. preferable. As such a method, as shown in FIG.
A vulcanized or semi-vulcanized endless annular pre-cured tread 8 previously molded with a tread pattern is applied to the belt layer 5.
After being arranged on the outer periphery of No. 6, vulcanization molding of the tire may be performed.

In this case, since the pre-cured tread 8 has a tread pattern in advance, there is no need to perform a belt lift at the time of vulcanization molding, and the cost and the number of mold surfaces are greatly reduced. Time can also be reduced.
That is, the molding die may be a local one in which a predetermined tread pattern is preliminarily molded for the precured tread 8, and the base tire 7 can be used in common for a plurality of types of treads. Therefore, the cost of the entire mold and the number of mold surfaces can be greatly reduced. Also, when vulcanizing the entire tire, the thickness of the shoulder portion of the tread substantially determines the length of vulcanization time, so even though the other parts have already been vulcanized, Although it was necessary to continue the vulcanization until the vulcanization of the shoulder portion was completed, the use of the pre-cured tread 8 can effectively shorten the vulcanization time.

As another vulcanization molding method that does not require a belt lift, a tread rubber composed of unvulcanized rubber is continuously extruded onto the outer circumference of the belt layers 5 and 6 from an extruder, and the tread rubber is subjected to gold. A tread pattern may be formed by pressing a mold. In this case, it is not necessary to perform a belt lift, and if the base tire 7 is in a vulcanized or semi-vulcanized state, the mold cost and the number of mold surfaces can be greatly reduced in the same manner as above, and the vulcanization time can be reduced. Can be shortened.

[0021]

[Example] The tire size was 195 / 70R14 91H.
Conventional tires, comparative tires, and tires 1 to 3 of the present invention were manufactured in which only the belt structure was changed as follows.

Conventional tire carcass side belt layer Code: Steel cord 1 × 4 (0.25) Cord density: 40/5 cm Cord angle: 24 °, Total belt width: 150 mm Belt layer on tread side Code: Steel cord 1 × 4 (0.25) Cord density: 40 cords / 5 cm Cord angle: 24 °, Total belt width: 140 mm Belt cover layer Cord: Nylon cord 1260d / 2 Cord density: 40 cords / 5 cm Cord angle: 0 °, Total belt Width: 150 mm Tread: After extrusion, vulcanization molding was performed in a mold.

Belt layer on comparison tire carcass side Code: Steel cord 1 × 4 (0.25) Cord density: 40 cords / 5 cm Cord angle: 24 °, Total belt width: 150 mm Belt layer on tread side Code: Steel cord 1 × 4 (0.25) Cord density: 40/5 cm Cord angle: 24 °, Total belt width: 130 mm Tread: After extrusion, vulcanization molding was performed in a mold.

Tire 1 of the present invention 1 A belt layer on the carcass side and tread side EHM polyester 1500d / 3 is coated at a cord density of 10 strands / cm with a calender material wound spirally into a tube, and the tube is flattened to a width. A 15 mm tape was formed, and the tape was spirally wound about 10 times in the tire circumferential direction while meandering so that the maximum inclination angle with respect to the tire circumferential direction was 15 °, so that the total belt width was 150 mm.

Tread: After extrusion, vulcanization molding was performed in a mold. Inventive tire 2 Belt layer on carcass side and tread side A calendar material coated with an aromatic polyamide 1500 d / 2 at a cord density of 8 strands / cm is spirally wound into a tube, and the tube is flattened to a width of 15 mm. A tape was formed, and the tape was spirally wound about 10 times in the tire circumferential direction while meandering so that the maximum inclination angle with respect to the tire circumferential direction was 15 °, so that the total belt width was 150 mm.

Tread: After extrusion, vulcanization molding was performed in a mold. The present tire 3 belt layer on the carcass side and tread side A calendar material coated with rayon 1690d / 2 at a cord density of 10 / cm is spirally wound into a tube, and the tube is flattened to form a 15 mm wide tape. The tape was meandered so that the maximum inclination angle with respect to the tire circumferential direction was 15 °, and the tape was spirally wound about 10 times in the tire circumferential direction to have a total belt width of 150 mm.

Tread: An endless annular precured tread was used, and vulcanization molding was performed in a mold having no pattern. With respect to these test tires, weight, molding productivity, rolling resistance, uniformity, high-speed durability, steering stability, vulcanization time, and mold cost were evaluated by the following test methods, and the results are shown in Table 1. .

Weight: The weight of each test tire was measured and expressed as an index with the conventional tire being 100. The smaller the index value, the lighter the weight. Molding productivity: For each test tire, the time required for molding was measured, and was indicated by an index with the conventional tire being 100. The smaller the index value, the better the molding productivity.

Rolling resistance: Each test tire was 1.9k in air pressure.
g / cm ² , mounted on a rim having a rim size of 14 × 51 / 2JJ, and the rolling resistance (RR) was measured by an indoor drum-type rolling resistance tester having a drum diameter of 1707 mm. . The smaller the index value, the lower the rolling resistance.

Uniformity : Radial force variation (RFV) was measured in accordance with the uniformity test method for automobile tires of JASO C607.
The index is shown as an index with the conventional tire being 100. The smaller the index value, the better the uniformity. High-speed durability: JIS on a drum with a drum diameter of 1707 mm
After the high-speed durability test of D 4230 was performed, the speed when the tire was broken by accelerating at 10 km / hr every 30 minutes was measured. The higher the index value, the better the high-speed durability.

[0031]Driving stability:Domestic 2.5 liter class
1.9kg / cm air pressure of each test tire on passenger car ^Two,load
Tested for handling stability with 450kg weight
It was evaluated by a feeling test by a driver. Evaluation
The results were shown in three stages: good, normal and bad.

Vulcanization time: The time required for vulcanization of each test tire was measured, and the result was indicated by an index with the conventional tire being 100. The smaller the index value, the shorter the vulcanization time. Die cost: The die cost required for manufacturing a tire with a daily amount of 1000 tires was calculated, and the cost was shown as an index with the conventional tire being 100. The smaller the index value, the lower the mold cost.

[0033]

As is clear from Table 1, the tires 1 to 3 of the present invention have lower rolling resistance by weight, higher molding productivity, better uniformity and higher speed durability than the conventional tires. And steering stability were excellent.
Further, in the tire 3 of the present invention, it was possible to further reduce the vulcanization time and the mold cost.

[0035]

As described above, according to the present invention, at least one belt layer is provided on the outer peripheral side of the carcass layer in the tread portion, and the plurality of organic fiber cords are aligned in parallel with the belt layer. The calendered material is spirally wound into a tube, and the tube is flattened to a width of 5 mm.
The tape was formed into a tape of up to 20 mm, and the tape was wound continuously multiple times while meandering so that the maximum inclination angle with respect to the tire circumferential direction was in the range of 5 ° to 25 °. Thus, a pneumatic radial tire for a passenger car which has high uniformity, good uniformity, and can be improved in high-speed durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing a belt structure of a pneumatic radial tire for a passenger car according to an embodiment of the present invention.

FIG. 2 is a meridional section of the tire according to the embodiment of FIG. 1;

FIG. 3 is a meridional sectional view of a pneumatic radial tire for a passenger car according to another embodiment of the present invention.

FIGS. 4A to 4C are perspective views showing steps of a method for manufacturing a tape according to the present invention.

[Explanation of symbols]

 2 Carcass layer 4 Tread section 5, 6 Belt layer 16 Organic fiber cord 17 Matrix 18 Calender material 19 Tube 20 Tape

Claims (5)

[Claims] At least one belt layer is provided on an outer peripheral side of a carcass layer in a tread portion, and the belt layer is formed by spirally winding a calendar material in which a plurality of organic fiber cords are arranged in parallel to form a tube. At the same time, the tube is flattened and formed into a tape having a width of 5 to 20 mm.
A pneumatic radial tire for passenger cars that has a structure wound continuously multiple times while meandering in the range of. 2. The pneumatic radial tire for a passenger car according to claim 1, wherein the belt layer has at least two layers, and a meandering pitch of the tape in the tire circumferential direction is shifted between layers. 3. The organic fiber cord is at least one of organic fibers selected from the group consisting of polyester fiber, aromatic polyamide fiber, polyarylate fiber, polyparaphenylene benzobisoxazole fiber, polyvinyl alcohol fiber, rayon fiber and nylon fiber. The pneumatic radial tire for a passenger car according to claim 1 or 2, which is a twisted cord obtained by twisting one kind. 4. The pneumatic radial tire for a passenger car according to claim 1, wherein an endless annular precured tread in which a tread pattern is previously formed is disposed on an outer periphery of the belt layer. 5. The tread pattern according to claim 1, wherein an unvulcanized tread rubber is continuously extruded on the outer periphery of the belt layer, and a mold is pressed against the tread rubber to form a tread pattern. A pneumatic radial tire for a passenger car according to claim 1.