JP2001187510A - Fabric with rubber for carcass ply and pneumatic tire using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unify the spring elasticity of a carcass in the peripheral direction even if the cord density in a cord fabric is uneven, and improve the uniformity while a stitch opening preventing effect of a tire cord is kept. SOLUTION: A fabric with rubber 10 has a tire cord 11 whose cord density is almost uniform over the whole width, and Mooney viscosity Ve of topping rubber Ge arranged in the side edge region Ye of the cord fabric 13 is made 1.05-1.20 times the Mooney viscosity Vc of topping rubber Gc arranged in the central region Yc. Modulus at 100% of the topping rubber Ge after vulcanization is almost equal to that of the topping rubber Gc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubberized fabric for a carcass ply which can improve the uniformity of a tire and a pneumatic tire using the same.

[0002]

2. Description of the Related Art As a ply material of a carcass constituting a skeleton of a pneumatic tire, as shown in FIG. 5A, generally, as shown in FIG. 5A, a warp made of a tire cord a is entangled with the tire cord a at a relatively coarse interval. A fabric f with rubber is used in which the front and back of a woven fabric c woven with thin weft b are covered with topping rubber g.

[0003] The fabric f with rubber has a sheet angle of α (approximately 75 to 90 degrees for radial tires) with respect to the tire cord a and a length corresponding to a desired carcass ply width w. After being cut into pieces f1, a long strip in which the tire cords a are arranged at the angle α with respect to the tire equator CO by sequentially joining the non-cut side edges fe and fe of each sheet piece f1. It has been converted to ply material d.

Then, the ply material d is put into a tire forming apparatus, and is wound around a forming drum i in a circumferential direction as shown in FIG. 5B, for example, and then expanded between bead cores to form a toroid. A raw tire is formed while being shaped.

[0005] However, when shaping the ply material d and vulcanizing a green tire, for example, in the vicinity of the joint j of the sheet piece f1,
The gap between the tire cords a is large, and the openings tend to be easily generated.

Conventionally, as shown in FIG. 6A, in order to prevent this opening, a cord density M on the side edge region Ye side of the tire cord a in the cord fabric c is conventionally used.
Is relatively increased as compared with the code density M on the central region side.

[0007]

However, when a tire is formed using such a cord fabric c, the tire shown in FIG.
As shown in the figure, a region where the code density is high (corresponding to the side edge region Ye) and a region where the code density is low (corresponding to the central region Yc) in the carcass k.
Appear alternately and repeatedly in the circumferential direction. As a result, the circumferential rigidity of the carcass k becomes non-uniform, causing a problem of lowering uniformity.

Accordingly, the present invention sets the cord density of the tire cord substantially equal over the entire width of the cord fabric,
On the basis of increasing the Mooney viscosity of the topping rubber Ge arranged in the side edge region from the Mooney viscosity of the topping rubber Gc arranged in the center region, while maintaining uniform spring elasticity of the carcass and improving uniformity. ,
An object of the present invention is to provide a rubberized fabric for a carcass ply and a pneumatic tire using the same, which can effectively prevent the opening of a tire cord which is likely to occur during shaping or vulcanization molding.

[0009]

Means for Solving the Problems In order to achieve the above object, a first invention of the present application is directed to a carcass ply for a carcass ply in which the front and back of a cord fabric woven by a weft and a warp consisting of a tire cord are covered with topping rubber. A rubberized fabric, wherein the cord fabric has a cord density of tire cords substantially equal over the entire width of the cord fabric, and a topping arranged in a side edge region having a width from a side edge of 70 to 150 mm. The Mooney viscosity of the rubber Ge is 1.05 to 1.20 times the Mooney viscosity of the topping rubber Gc disposed in the central region sandwiched between the side edge regions, and the topping rubber Ge after vulcanization. Is characterized by being substantially equal to the 100% modulus of the topping rubber Gc.

A pneumatic tire according to a second aspect of the present invention is characterized by using the above-mentioned rubberized fabric.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a rubberized fabric for a carcass ply according to the first invention of the present application will be described with reference to the drawings together with an embodiment of a pneumatic tire using the same according to the second invention. FIG. 1 exemplifies a meridional section when the pneumatic tire 1 is formed as a radial tire for a passenger car, and shows a tread portion 2 and a pair of sidewall portions 3 extending inward in the tire radial direction from both sides thereof. And a bead portion 4 located at an inner end of each sidewall portion 3.

Further, the pneumatic tire 1 is provided with a toroidal carcass 6 extending between the beads 4 and a belt layer 7 disposed inside the tread 2 and outside the carcass 6. I have.

The carcass 6 is formed of one or more carcass plies 6A in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire circumferential direction, in this embodiment, one carcass ply 6A. As the carcass cord, an organic fiber cord such as nylon, polyester, rayon, or aromatic polyamide is preferably employed, but a steel cord may be employed according to the size, category, or requirement of the tire.

The carcass 6 is locked on both sides of the main body 6a extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3 by being turned from the inside to the outside around the bead core 5. It has a folded portion 6b to be formed. A bead apex rubber 8 extending from the bead core 5 to the outside in the tire radial direction in a tapered shape is disposed between the main body 6a and the folded portion 6b. In this example, the turn-back portion 6b is formed at a bead base line B at the outer end in the radial direction.
The height from L is higher than the height of the radially outer end of the bead apex rubber 8 to form a so-called high turn-up structure, which cooperates with the bead apex rubber 8 to reinforce the bead portion 4 and reduce the tire lateral rigidity. Is increasing. When the carcass 6 is formed by a plurality of plies, it is preferable that at least one ply has a high turn-up structure.

The belt layer 7 is composed of two or more belt ply members 7 in which highly elastic belt cords are arranged at an angle of 10 ° to 35 ° with respect to the tire circumferential direction.
A, 7B. Each belt ply 7A, 7B
The belt cords are arranged in different directions so as to intersect with each other between the plies, thereby increasing the belt rigidity by the triangle structure of the cords, and reinforcing substantially the entire width of the tread portion 2 with a tag effect. As the belt cord, a steel cord or a highly elastic fiber cord having a strength close to that of steel, such as an aromatic polyamide fiber or an aromatic polyester fiber, is preferably used.

A band layer 9 covering at least the outer end of the belt layer 7 in the tire axial direction can be disposed outside the belt layer 7 for the purpose of improving high-speed running performance, as in this embodiment. In this example, the band layer 9 is formed of an edge band ply 9A covering only the outer end and a full band ply 9B covering substantially the entire width of the belt layer 7. Each of the band plies 9A and 9B is formed by spirally winding a band cord of an organic fiber such as nylon, polyester, rayon, or aromatic polyamide substantially in parallel with the tire circumferential direction.

In the present application, the carcass ply 6A
Is formed using a fabric with rubber 10 (shown in FIG. 2) as described below.

Specifically, the fabric with rubber 10 is
A warp composed of a tire cord (carcass cord) 11,
The tire cord 11 has relatively coarse intervals (for example, 10 to 10).
A long cord fabric 13 woven with a weft thread 12 entangled at an interval of about 20 mm) is provided with an adhesive application treatment (so-called dip treatment). Coated with rubber G.

Here, the weft 12 is mainly used for the tire cord 1 when applying the adhesive and when coating with rubber.
1 is used to prevent loosening, but at the time of vulcanization molding, this weft 12 hinders uniform inflation such as unnecessarily constraining the tire cord 11, and may cause an irregular arrangement of the tire cord. is there. Accordingly, in the case of the fabric 10 with rubber, after the rubber is coated, the weft 12 is cut using, for example, a cutting device described in JP-A-63-38006.
No. 8457, using a weft removing device.
Can be removed. In other words, the rubberized fabric 10 of the first invention can include a fabric in which the weft yarn 12 has been cut, or a fabric in which the weft yarn 12 itself has been removed from the weft yarn.

The present invention is characterized in that the cord density of the tire cords 11 in the rubberized fabric 10 is set to be substantially equal over the entire width of the cord fabric 13. Further, as another feature, FIG.
As shown in the figure, the Mooney viscosity Ve of the topping rubber Ge arranged in the side edge region Ye of the screen fabric 13 is changed to the central region Y.
c is set to 1.05 to 1.20 times the Mooney viscosity Vc of the topping rubber Gc disposed in the c.

Here, "cord density" means the number of tire cords 11 per unit width. Further, “the cord density is substantially equal over the entire width of the cord fabric 13” means that the maximum number X1 of cords per 5 cm width in the cord fabric 13 is X1.
And the ratio X1 / X2 to the minimum value X2 means 1.05 or less, and preferably 1.03 or less.

The “side edge area Ye” is a woven cloth 13
Means a width region having a width LW from the side edge 13a of 70 to 150 mm, and a region sandwiched between the side edge regions Ye, Ye is referred to as a “central region Yc”.

The above "Mooney viscosity" refers to JIS K6
In accordance with the Mooney viscosity test described in item 6 of 300 (Physical test method for unvulcanized rubber), the shape of the rotor was L-shaped, and the temperature was measured after preheating at 130 ° C for 1 minute and rotating the rotor for 4 minutes. Value.

As described above, the fabric 1 with rubber
On the other hand, 0 indicates that the cord density of the cord fabric 13 is uniform, so that when the ply material 15 for the carcass ply as described above (shown in FIG. 4) is formed, the cord density of the carcass 6 is reduced. The dense side edge region Ye and the sparse central region Yc can be prevented from repeatedly appearing in the circumferential direction. As a result, the spring elasticity of the carcass 6 is made uniform in the circumferential direction, and uniformity can be improved.

On the other hand, the Mooney viscosity Ve of the topping rubber Ge is increased at a predetermined ratio as compared with the Mooney viscosity Vc of the topping rubber Gc, so that the rubber deformation of the topping rubber Ge in an unvulcanized state is made difficult. . As a result, even when the cord density is made uniform as described above, the opening of the tire cord near the joint portion, which has conventionally occurred at the time of shaping and vulcanization molding, can be effectively suppressed. .

However, in order to secure the effect of improving the uniformity, at least 100% modulus Mc of each of the topping rubbers Gc and Ge after vulcanization.
Me needs to be approximately equal to each other. Note that "substantially equal" means that the ratio Me / Mc is in the range of 0.9 to 1.1. If the ratio exceeds this range, the improvement effect is impaired due to the difference in rubber physical properties, and the durability is increased. There is also concern about the decline.

In order to increase the Mooney viscosity Ve of the topping rubber Ge, for example, means for increasing the blending amount of carbon in the compounded rubber as compared with the topping rubber Gc can be suitably employed. At this time, by adjusting the amount of sulfur and / or the vulcanization accelerator, the 100%
Modulus Mc and Me can be adjusted substantially equally. Table 1 shows an example of a compounded rubber suitable as the topping rubbers Ge and Gc.

[0028]

[Table 1]

If the Mooney viscosity ratio Ve / Vc is less than 1.05, the effect of preventing the tire cord from opening becomes insufficient. If it exceeds 1.20, the topping rubber G
In addition to greatly impairing the processability of e, heat generation is large and burns are liable to occur. As a result, the line speed in the topping step needs to be drastically reduced, thereby lowering productivity. Accordingly, from the viewpoint of such productivity, the Mooney viscosity Ve of the topping rubber Ge is 47ML1 + 4 (130
゜ C) It is preferable to stop it below, and it is important to use it in the side edge region Ye having a width of 70 to 150 mm.

[0030]

EXAMPLE A rubberized fabric based on the specifications in Table 2 was formed, and a pneumatic tire (tire size 225) having the structure shown in FIG.
/ 60R16). The productivity of the fabric with rubber, the incidence of tire cord openings, and the uniformity of the test tire were tested. The results are shown in Table 2.

(1) Productivity: The limit process speed at which rubber scorch does not occur in the topping process of coating the cord fabric with the topping rubber is indicated by an index with Comparative Example 1 being 100. The higher the value, the better the productivity.

(2) Occurrence rate of tire cord openings: Calculated from the number of tires having openings and the number of tires (each 1000 tires), which were visually confirmed by an introspection during production.

(3) Uniformity According to JASOC607 (uniformity test method for automobile tires), test tires under the conditions of a rim (16 × 6.5 JJ), an internal pressure (200 kPa) and a load (5.50 kN). (Lateral force variation) was measured and indicated by an index with Comparative Example 1 being 100. The smaller the value, the better the uniformity.

[0034]

[Table 2]

As shown in the table, it can be confirmed that the tires of the examples maintain the productivity and improve the uniformity while suppressing the occurrence of tire cord openings.

[0036]

Since the present invention is configured as described above,
While the spring elasticity of the carcass is kept uniform and the uniformity is improved, it is possible to effectively prevent the opening of the tire cord which tends to occur at the time of shaping, vulcanization molding, and the like. Moreover, productivity can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire according to an embodiment of the present invention.

FIG. 2 is a front view of a fabric with rubber used for the carcass ply.

FIG. 3 is a sectional view thereof.

FIG. 4 is a front view illustrating a ply material from a rubberized fabric.

5A is a diagram illustrating the formation of a ply material from a fabric with rubber, and FIG. 5B is a diagram illustrating the formation of a carcass ply from the ply material.

FIG. 6 (A) is a diagram showing a cord density distribution in a cord fabric, and FIG. 6 (B) is a perspective view for explaining a problem caused thereby.

[Explanation of symbols]

 Reference Signs List 10 fabric with rubber 11 tire cord 12 weft 13 blind fabric 13a side border of blind fabric Ge, Gc topping rubber Ye side border area Yc central area

Claims (2)

[Claims] 1. A rubber fabric for a carcass ply, wherein the front and back of a blind woven fabric woven by a weft and a warp made of a tire cord are covered with topping rubber, wherein the cord woven fabric has a cord density of a tire cord. The width of the mat is approximately equal over the entire width, and the Mooney viscosity of the topping rubber Ge arranged in the side edge region having a width from the side edge of 70 to 150 mm is in the central region sandwiched between the side edge regions. 1.05 of Mooney viscosity of topping rubber Gc to be distributed
A rubber fabric for a carcass ply, wherein the 100% modulus of the topping rubber Ge after vulcanization is substantially equal to the 100% modulus of the topping rubber Gc. 2. A pneumatic tire using the fabric with rubber according to claim 1.