JPH09220908A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provided a pneumatic radial tire free to manufacture with high productivity while improving high speed durability and reducing rolling resistance. SOLUTION: A pneumatic radial tire is constituted by forming a tape 6 converged by burying a plural number of reinforcing cords 5 in rubber by pulling them in order into a cross sectionally flat hollow belt body 7 in width equivalent to width of a belt layer by continuously and spirally winding it, arranging the hollow belt body 7 as a belt layer 3, forming a cross sectionally flat cylindrical continuous tube by spirally and continuously winding a plural number of the rubber coated reinforcing cords pulled in order with each other in parallel at a specified angle against the longitudinal direction, and spirally and continuously winding the continuous tube at least around outer peripheries of both side parts of the extreme outside belt layer in the cross direction a plural number of times.

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 which can be manufactured with high productivity while improving high-speed durability and reducing rolling resistance.

[0002]

2. Description of the Related Art Conventionally, a belt layer of a pneumatic radial tire is a rubberized sheet in which a reinforcing cord is embedded in rubber and has a cord angle of 10 ° to the tire circumferential direction.
It was formed by joining the belts with a width corresponding to the belt cut so as to be inclined at 30 ° and joining them in the tire circumferential direction. Therefore, there is a cut end face on both widthwise ends of the belt layer, and stress is unavoidably generated on the cut end face during running of the tire to cause separation between the rubber and the cord. Moreover, this separation is more noticeable as the traveling speed increases, so there is a problem that the high-speed durability is poor.

Further, as described above, a large number of steps such as making a sheet piece cut into a bias and joining the sheet pieces are required, which has been a factor of reducing productivity. On the other hand, in recent years, flattening has been progressing also in heavy vehicles such as trucks and buses and radial tires such as light trucks. However, as the tire becomes flatter, the load on the tire belt portion increases, and further separation of the belt edge, outer peripheral growth, and the like occur, which causes a problem that the high-speed durability is significantly reduced.

As a measure against such a load on the belt portion, as is often used in radial tires for passenger cars, a belt cover layer is provided so as to cover both sides or the entire surface in the width direction of the outermost belt layer. It is provided. However,
In the nylon fiber cord with a large elongation used as the cord of the belt cover layer of the passenger car tire, the hoop effect in the tire circumferential direction by the belt cover layer is not sufficient,
Therefore, the growth of the outer circumference could not be sufficiently suppressed.

Therefore, when steel cords or aromatic polyamide fiber cords having a large elastic modulus are used for the cords of the belt cover layer, since these cords have small elongation, the belt cover layer follows the lift (expanded diameter) during vulcanization. However, there is a problem in that it is impossible to manufacture a tire. Further, when the cords are arranged in the bias direction, cut end faces are formed at both widthwise ends of the belt cover layer, which causes a problem that edge separation occurs from the end faces.

[0006]

The object of the present invention is to achieve high-speed running without causing the above-mentioned problems even when the tire is flattened, particularly when the tire is a heavy-duty tire. It is an object of the present invention to provide a pneumatic radial tire that can be manufactured with high productivity while preventing outer circumferential growth to improve high-speed durability and reduce rolling resistance.

[0007]

SUMMARY OF THE INVENTION The present invention is a pneumatic radial tire having a plurality of belt layers arranged outside a carcass layer in a tread, a plurality of reinforcing cords aligned with each other, embedded in rubber, and converged into a tape. Are continuously wound in a spiral shape to form a hollow strip having a flat cross section having a width corresponding to the width of the belt layer, and the hollow strips are arranged as the belt layer and are aligned in parallel with each other. This rubberized reinforcing cord is continuously spirally wound at a predetermined angle with respect to the longitudinal direction to form a continuous tube having a flat tubular cross section, and the continuous tube is formed on at least both widthwise side portions of the outermost belt layer. It is characterized in that the belt cover layer is formed by continuously winding a plurality of times around the outer periphery in a spiral shape.

As described above, the hollow strip having a flat cross section having a width corresponding to the width of the belt layer is arranged as the belt layer, and the continuous tube having the flat cross section is provided on the outer periphery of at least both widthwise sides of the outermost belt layer. Since the belt cover layer is formed by spirally winding the belt cover several times continuously, the belt layer and the belt cover layer do not have cutting end faces at both widthwise ends, so that separation occurs between the rubber and the cord at both ends. Never. In addition, since there is no cut end face at both widthwise ends of the belt layer and the belt cover layer in this manner, the tensile rigidity in the tire circumferential direction of the belt portion (belt layer + belt cover layer) is increased, so rolling resistance can be reduced. .

Further, as described above, the tensile rigidity of the belt portion in the tire circumferential direction becomes high, the hoop effect in the tire circumferential direction by the belt layer and the belt cover layer becomes sufficient, and the outer peripheral growth can be sufficiently suppressed. Even when the tire is flattened so that the load on the belt layer is increased, the high-speed durability can be further improved. Further, the belt cover layer is composed of a continuous tube having a flat cross section, and this continuous tube can be stretched because it is formed by spirally winding a rubberized reinforcing cord at a predetermined angle with respect to the longitudinal direction. The belt cover layer can follow the lift during vulcanization.

In addition, since the hollow strip obtained by winding is arranged as a belt layer and the belt cover layer is formed by winding a continuous tube, a simple operation such as winding is mainly used, so that tire production is performed. It is possible to improve the sex.

[0011]

1 shows a cross section in the meridian direction of an example of a pneumatic radial tire of the present invention, FIG. 2 shows its belt structure, and FIG.
The belt part planarly viewed in (B) is shown. 1 and 2
In (A) and (B), the belt layer 3 is arranged outside the carcass layer 2 in the tread 1. Belt layer 3
Is a hollow strip 7 having a width corresponding to the belt layer width shown in FIG.
Is formed on the outer side of the carcass layer 2 over the entire circumference of the tire. The hollow strip 7 has a flat cross section as shown in FIG.
A tape 6 in which (organic fiber cords) are aligned, embedded in rubber, and bundled is continuously wound in a spiral to form a tubular body,
This tubular body is crushed along its longitudinal direction.

As shown in FIG. 4, a core material 8 such as a rubber sheet may be inserted into the hollow portion of the hollow belt 7 along its longitudinal direction. Thereby, the rigidity of the belt layer 3 can be further enhanced. To arrange the hollow belt-shaped body 7 on the outer side of the carcass layer 2 over the entire circumference of the tire, for example,
The hollow strip 7 may be wound around the outer side of the carcass layer 2, and both ends in the longitudinal direction thereof may be butted against each other and joined together. At the time of this joining, a slight gap may be provided between the adjacent terminals. When the hollow belt-shaped body 7 is arranged outside the carcass layer 2 to form the belt layer 3 as described above, the cord angle of the belt layer 3 with respect to the tire circumferential direction is 10 ° to 30 °.
It is better to make it °. This is so that the belt layer 3 can follow the lift during vulcanization. This cord angle is equal to the cord angle of the hollow strip 7. This is because when the hollow strip 7 is wound around the carcass layer 2, the longitudinal direction of the hollow strip 7 becomes the tire circumferential direction.

The outer layer of the belt layer 3 (Because the belt layer 3 is composed of the hollow belt-shaped body 7, it has a two-layer laminated structure of an inner layer and an outer layer, so the outer layer corresponds to the outermost belt layer). As shown in FIGS. 1 and 2A and 2B, the belt cover layer 4 is arranged on the outer periphery so as to cover the entire surface thereof. The belt cover layer 4 may be arranged at least on the outer circumferences of both outer sides of the belt layer 3 in the width direction, and may not be arranged so as to cover the entire surface of the outer layer of the belt layer 3. Good. In addition, CL in FIG. 1 represents a tire equator line.

The belt cover layer 4 includes a continuous tube 10 having a flat tubular cross section shown in FIG. 5, which is continuously spirally wound a plurality of times over the entire outer circumference of the outer layer of the belt layer 3 from one end to the other end in the width direction. It is formed by winding. This continuous tube 10 has a rubberized reinforcing cord formed by embedding a plurality of reinforcing cords 12 (organic fiber cords) in rubber, preferably 5 to 100 in parallel with each other at a predetermined angle (10 °) with respect to the longitudinal direction. It can be formed by continuously spirally winding at about 30 °) into a tubular body, and crushing the tubular body along its longitudinal direction. Also, using a die capable of inserting a predetermined number of reinforcing cords into a tuber (extruding device) capable of forming a tubular rubber sheet, the reinforcing cords are extruded while being embedded in the tubular rubber sheet, and After rotating and arranging the reinforcing cord in a spiral state,
The continuous tube 10 can also be formed by crushing with a roller or the like.

The width of the continuous tube 10 is 5 mm to 60 m.
m. If it is less than 5 mm, the width will be too narrow and the productivity of the tubular body will be reduced.
This is because the width of the terminal portion of 0 becomes too long, which deteriorates tire uniformity and durability. The cord angle of the belt cover layer 4 with respect to the tire circumferential direction is 10 ° to 3
It should be 0 °. This is because the belt cover layer 4 can easily follow the lift during vulcanization. In order to set the cord angle of the belt cover layer 4 to 10 ° to 30 °, as described above, the rubberized reinforcing cord is continuously spirally wound at a predetermined angle with respect to the longitudinal direction to form the continuous tube 10. At this time, the predetermined angle may be set to 10 ° to 30 °. This is because the longitudinal direction of the continuous tube 10 becomes substantially the tire circumferential direction when the belt cover layer 4 is formed.

A core material such as a rubber sheet may be inserted inside the continuous tube 10 along the longitudinal direction thereof. This is to increase the rigidity of the belt cover layer 4. When the continuous tube 10 is wrapped around the outer layer of the belt layer 3, the adjacent sides of the continuous tube 10 are butted against each other, or slightly overlapped (about -5 mm) with a step, or slightly. A space (+5 mm) or the like may be provided.

The organic fiber cords constituting the reinforcing cords 5 forming the hollow strips 7 or the reinforcing cords 12 forming the continuous tube 10 are, for example, aromatic polyamide fibers, polyarylate fibers, polyparaphenylenebenzbisoxazole fibers, A twisted yarn obtained by twisting one or more fibers selected from polyvinyl alcohol fibers.

Further, the reinforcing cord 5 or the reinforcing cord 12
Has a tensile elastic modulus of 3000 kgf / mm ^TwoAbove, tensile strength
150 kgf / mm^TwoHave the above. Tensile modulus is 30
00 kgf / mm^TwoIf the value is less than 1, the belt rigidity will be insufficient and
Not only the growth of the rut section is reduced, but also the steering performance is reduced. Pull
Tensile strength 150kgf / mm^TwoBelow, the belt strength is
The tire strength is reduced.

The present invention described above can be applied not only to passenger car tires, but also to particularly excellent high-speed durability when applied to flattened heavy-duty tires.

[0020]

[Examples] With respect to the tire of the present invention and the conventional tire having the following belt structure, high-speed durability, rolling resistance, and outer peripheral growth were evaluated under the following conditions. Table 1 shows the results. Here, the belt structure of each tire is composed of 1B to 4B. 1B is the first belt layer counted from the carcass layer in the tread direction, 2B is the second belt layer counted from the carcass layer in the tread direction, and 3B is the third belt layer counted from the carcass layer in the tread direction. The belt layer, 4B, represents the fourth belt layer counted from the carcass layer in the tread direction.

Therefore, in the belt layer structure of the present invention shown in FIG. 1, the inner layer of the belt layer 3 is 1B and the outer layer is 2B, and the inner layer of the belt cover layer is 3B and the outer layer is 4B. The tire of the present invention has the belt structure shown in FIG.

1B: Kevlar (aromatic polyamide fiber cord) 300
0d / 2, number of ends 23 / 5cm, width 200mm, cord angle 20 °. 2B: Same as 1B. 3B: Kevlar (aromatic polyamide fiber cord) 300
0d / 2, number of ends 23 / 5cm, width 30 × 5mm,
Code angle 20 °. 4B: Same as 3B.

A conventional tire has a belt structure including four belt layers in which cords cross each other between plies and have cut end faces on both ends in the width direction. 1B: Steel cord 3 + 6 × 0.35HT, number of ends 23/5 cm, width 180 mm, cord angle 56 °.

2B: Same as 1B except width 210 mm, cord angle 20 °. 3B: Same as 1B except that the width is 190 mm and the cord angle is 20 °. 4B: Steel cord 4 × 2 × 0.31HE, number of ends 20/5 cm, width 80 mm, cord angle 20 °. Condition Air pressure; 8.0kgf / cm ² (800KPa), rim; 22.5 × 8.25, tire size; 11/70 R22.5 Other tire structure other than belt layer and belt cover layer,
The dimensions are common.

High speed durability : After the JATMA high speed durability test was completed with a drum diameter of 1707 mm, the test was continued until the tire broke by accelerating at a load of 4000 kgf and 80 km / hr. The result is shown as an index with the conventional tire being 100. Larger numbers are better. Rolling resistance : drum diameter 1707mm, load 2725kgf, speed
The rolling resistance was measured by measuring the resistance at 50 km / hr. The result is shown as an index with the conventional tire being 100. Larger numbers are better.

Perimeter growth : Inflated after mounting the rim,
The amount of peripheral growth was measured and the rigidity of the belt portion was compared. The result is shown as an index with the conventional tire being 100. Larger numbers are better.

[0027] As is clear from Table 1, the tire of the present invention has high-speed durability,
It can be seen that the rolling resistance and the outer peripheral growth are excellent.

[0028]

As described above, according to the present invention, in a pneumatic radial tire in which a plurality of belt layers are arranged outside a carcass layer in a tread, a plurality of reinforcing cords are aligned and embedded in rubber. The converged tape is continuously spirally wound to form a hollow strip having a flat cross section having a width corresponding to the width of the belt layer, and the hollow strips are arranged as the belt layers and are aligned in parallel with each other. The plurality of rubberized reinforcing cords are continuously spirally wound at a predetermined angle with respect to the longitudinal direction to form a continuous tube having a flat tubular cross-section, and the continuous tube is at least the width of the outermost belt layer. Since the belt cover layer is formed by continuously winding it around the outer periphery of both sides in a spiral direction multiple times, high load is applied to the belt layer. To prevent the outer circumferential growth can be reduced rolling with improved high-speed durability, it is possible to follow the belt cover layer yet to lift vulcanization. Further, a simple operation of winding is mainly used, such as arranging a hollow belt obtained by winding as a belt layer and forming a belt cover layer by winding a continuous tube. Since the step of cutting the layer or the sheet for forming the belt cover layer is not necessary, the tire productivity can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view in the meridian direction of an example of a pneumatic radial tire of the present invention.

2A and 2B show a belt structure of the pneumatic radial tire of FIG. 1, in which FIG. 2A is a sectional explanatory view thereof, and FIG. 2B is a plan view explanatory view thereof.

FIG. 3 is a perspective explanatory view showing an example of a hollow strip for forming a belt layer in the present invention.

FIG. 4 is a perspective explanatory view showing another example of a hollow belt-shaped body for forming a belt layer in the present invention.

FIG. 5 is a perspective explanatory view showing an example of a continuous tube forming a belt cover layer in the present invention.

[Explanation of symbols]

1 tread 2 carcass layer 3 belt layer
4 Belt cover layer 5 Reinforcing cord 6 Tape 7 Hollow strip
8 Core material 10 Continuous tube 12 Reinforcement cord

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location D02G 3/48 D02G 3/48 (72) Inventor Eiji Igarashi 2-1, Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber stock company Hiratsuka factory

Claims (6)

[Claims] 1. A pneumatic radial tire having a plurality of belt layers arranged outside a carcass layer in a tread, wherein a plurality of reinforcing cords are aligned and embedded in rubber, and a converged tape is continuously spirally wound. It is turned to form a hollow strip having a flat cross section having a width corresponding to the width of the belt layer, the hollow strip is arranged as the belt layer, and a plurality of rubberized reinforcing cords aligned in parallel with each other are longitudinally arranged. To form a continuous tube having a flat tubular cross section by continuously winding the spiral tube at a predetermined angle with respect to the direction. A pneumatic radial tire that is wound multiple times to form a belt cover layer. 2. The reinforcing cord is a twisted yarn formed by twisting one or more kinds of organic fibers selected from aromatic polyamide fibers, polyarylate fibers, polyparaphenylenebenzbisoxazole fibers, and polyvinyl alcohol fibers. The pneumatic radial tire according to claim 1. 3. The tensile strength of the reinforcing cord is 3000 k.
The pneumatic radial tire according to claim 1 or ^2, which has a gf / mm ² or more and a tensile strength of 150 kgf / mm ² or more. 4. The pneumatic radial tire according to claim 1, wherein a core material made of a rubber sheet is inserted inside the hollow belt or the continuous tube along a longitudinal direction thereof. . 5. The cord angle of the belt layer with respect to the tire circumferential direction is 10 ° to 30 °.
The pneumatic radial tire according to any one of the above items. 6. The pneumatic radial tire according to claim 1, wherein a cord angle of the belt cover layer with respect to a tire circumferential direction is 10 ° to 30 °.