JP2000198312A - Tire reinforcing material and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire reinforcing material capable of ensuring adhesive strength with rubber and improving exfoliation resistance, fatigue resistance and high-speed durability when used for a tire reinforcing layer by forming a surface of a flat wire rod corrugated into an uneven surface having projections and depressions and satisfying a specific condition, as a reinforcing material used for a tire reinforcing layer, and to provide a pneumatic tire using the reinforcing material. SOLUTION: At least both sides of a flat wire rod which is corrugated and has an oblate shape in a cross-section are formed in an uneven surface 4 wherein the uneven difference between projections and depressions is 3 micron and more. A surface area ratio to a surface area before making the projections and depressions is allowed to be 1.3 to 3.0. As an uneven surface, a large number of string grooves 2 having an angle 0 deg. to 45 deg. to a longitudinal direction of the flat wire rod are formed, or either one or both of fine projections and depressions are scattered to form the surface uneven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tire reinforcing material and a pneumatic tire used for a reinforcing layer of a tire.

[0002]

2. Description of the Related Art In a pneumatic tire such as a radial tire, a steel cord formed by twisting a plurality of strands is generally used for a reinforcing layer such as a belt. Usually, a large number of cords are arranged in parallel and covered with rubber to form a sheet for use.

[0003] Steel cords are expensive due to heat treatment, wire drawing, twisting, and the like in production, are less flexible than organic fiber cords, and are subject to wear between core wires and cores. There was a problem such as the generation of rust due to the penetration of moisture.

[0004] For this reason, it has been proposed to use a flat wire made of steel having a flat cross section which has been subjected to corrugation in consideration of shock absorption, fatigue resistance, etc. JP-A-60-110497, Jpn.
396).

In the case of a normal twisted cord, the cord surface has irregularities peculiar to the twisted structure, the surface area per unit width is larger than that of a simple flat wire, and the adhesive strength with rubber can be sufficiently ensured. However, such a steel cord,
If the flat wire is simply replaced with the flat wire, the surface area per unit width decreases, the adhesive strength with rubber becomes insufficient, and the high-speed durability becomes poor.

The present invention has been made in view of the above, and as a reinforcing material used for a reinforcing layer of a tire, the surface of a corrugated flat wire is formed into an uneven surface satisfying specific conditions. By doing so, it is possible to provide a reinforcing material that can sufficiently secure the adhesive force with rubber and improve the peeling resistance, fatigue resistance, and high-speed durability when used as a reinforcing layer of a tire. It is intended to provide a pneumatic tire using a material.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a tire reinforcing material according to the first aspect of the present invention is formed of a flat wire having a flat cross-section subjected to corrugation. At least one of the front and back surfaces of the flat wire is formed on an uneven surface having an unevenness of 3 μm or more, and a surface area ratio to a surface area before the unevenness is provided is in a range of 1.3 to 3.0. I do.

[0008] In the above-mentioned reinforcing material for a tire, the reason why the unevenness difference is 3 μm or more is that if the unevenness difference is smaller than 3 μm, the effect of improving the adhesive strength is hardly obtained. Also, if the unevenness difference is too large, a problem with the strength of the flat wire will occur,
It is preferable that the unevenness difference is set at most to 1/5 or less of the thickness of the flat wire.

The above surface area ratio, that is, the ratio (S / Sa) of the surface area (S) of the entire flat wire having irregularities to the surface area (Sa) before the irregularities is set to 1.3 to 3.0. The reason is that when the surface area ratio is smaller than 1.3, the effect of forming the uneven surface is small, and when the surface area ratio exceeds 3.0, the concave portions of the uneven surface become deep and large. This is because the rigidity and tensile strength of the wire itself are reduced, and the peel resistance and the high-speed durability are rather reduced.

[0010] In the reinforcing material of the invention, the uneven surface may have a groove of 0 ° to 45 ° with respect to the longitudinal direction of the flat wire within the range of the unevenness difference and the surface area ratio. Can be formed at required intervals to form irregularities.

Further, as the uneven surface, one or both of fine concaves and convexes may be formed in a scattered manner to form an uneven surface. In this case, it is preferable that fine irregularities are formed over the entire surface by sandblasting as in claim 4.

It is preferable that the tire reinforcing material has a crimping rate of 2.0% or less as a whole of the reinforcing material determined by the following equation.

Crimping rate (%) = 100 (BA) / A where A: weight per unit length when straight (g /
m) B: Weight per unit length after crimping (g / m) That is, as shown in FIG. 3, the above crimping ratio varies depending on the amplitude (α) and pitch (P) of corrugating. On the other hand, if the crimp rate of the reinforcing material as a whole exceeds 2.0%, the elongation becomes too large and the steering stability is reduced. Further, the lower limit of the crimp ratio is 0.05%, and if it is smaller than this, the effect of performing the corrugating process will hardly be obtained.

According to a sixth aspect of the present invention, there is provided a pneumatic tire using the tire reinforcing material according to any one of the above inventions in at least one reinforcing layer.

[0015]

According to the tire reinforcing material of the present invention, at least one of the front and back surfaces of the corrugated flat wire is formed on an uneven surface having an unevenness of 3 microns or more. Since the surface area is larger than that of a relatively smooth wire rod made by wire processing, if this is embedded in rubber and used as a reinforcing layer of a tire, the bonding area with the rubber will increase and this will increase the surface area. In combination with the anchoring effect due to the unevenness of the surface, extremely excellent adhesive strength can be secured, and fatigue resistance and high-speed durability are improved. Of course, since the reinforcing member made of a flat wire is corrugated as a whole, appropriate flexibility can be secured, and good shock absorption resistance can be secured.

In particular, when the uneven surface is formed by grooves between 0 ° and 45 ° with respect to the longitudinal direction of the wire, the high-speed durability and the peeling resistance are improved. And fatigue resistance is also ensured.

Also, in the case where the uneven surface is formed with one or both of fine concaves and convexes in a scattered manner as in the case of the third aspect, the adhesive force is similarly improved. In particular, in the case of the fourth aspect, the entire surface of the flat wire is formed on a rough surface having irregularities, and the adhesive strength is further improved.

According to a fifth aspect of the present invention, the crimp ratio is 2.0%.
By setting as follows, excessive elongation and flexibility can be suppressed, and steering stability is also ensured satisfactorily.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged view showing a reinforcing material for a tire made of a steel flat wire (1) such as high-carbon steel having a flat cross section and having a corrugated shape having an amplitude in the thickness direction.
FIG. 2 is a cross-sectional view of the reinforcing member, and FIG. 3 is a side view of a part of the reinforcing member.

At least one of the front and back surfaces of the flat wire (1), that is, at least one surface on the long diameter side (both surfaces in the illustrated embodiment) is extended in the longitudinal direction of the wire by rolling with a grooved roll (2). Are formed at required intervals, and are formed on the uneven surface (4) by the groove (2) and the remaining convex ridge (3). Although it is possible to form only one of the front and back surfaces on the uneven surface, it is practical to form both the front and back surfaces on the uneven surface (4) as shown in the figure.
Good adhesive integrity with rubber is preferred.

The depth of the groove (2), that is, the difference (D) in unevenness between the groove (2) and the ridge (3) does not exceed 1/5 of the thickness (t) of the wire. To 3 μm or more, and formed on a rough surface with fine irregularities.

The surface area (S) of the flat wire (1) having the irregularities as described above is the surface area before the irregularities are formed, that is, the surface area (Sa) before the grooving by the grooving roll.
Is set so that the surface area ratio (S / Sa) with respect to the range is 1.3 to 3.0. Therefore, the depth, width and groove interval of each groove (2) are set so as to satisfy the surface area ratio described above.

The groove (2) is not limited to be formed at 0 ° with respect to the longitudinal direction of the wire as shown in the figure, and may be in a direction crossing the longitudinal direction of the wire. However, if the angle of the groove (2) with respect to the longitudinal direction of the wire exceeds 45 °, the fatigue resistance and the performance on rough roads are extremely reduced, so that the angle is in the range of 0 ° to 45 °. Is good.

The above-mentioned groove (2) is usually formed by rolling a flat wire (1) with a groove roll before corrugating, and forming a groove (2) on at least one of the front and back surfaces. Although it is formed on the surface (4), it is needless to say that grooving may be performed after corrugating, or grooving and corrugating may be performed in one step.

FIG. 4 shows that the surface of the flat wire (1) subjected to the corrugating process is formed in a lacquer shape by forming one or both of fine concaves and convexes in a scattered manner by means such as knurling or sandblasting. 5 shows an embodiment of a reinforcing material formed on a thin uneven surface (4a). The above sandblasting or knurling may be performed before or after the corrugating of the flat wire (1).

Also in the case of this embodiment, the unevenness due to the fine concaves and convexes is set to 3 microns or more within a range not exceeding 1/5 of the thickness (t) of the flat wire (1). The surface area is increased without lowering the strength of 1), and the surface area (S) is adjusted to the surface area ratio (S / Sa) to the surface area (Sa) before the unevenness is formed by sandblasting or the like.
Is set in the range of 1.3 to 3.0.

Also, at least one of the front and back surfaces (preferably, both surfaces) can be formed in the above-mentioned uneven shape. However, as shown in the drawing, the entire surface of the flat wire (1) is formed by sandblasting or the like. It is more preferable that the flat wire (1) is formed in a rubber to have good adhesion to the rubber when the flat wire (1) is embedded in the rubber.

In any of the above embodiments,
The flat wire (1) generally has a flat shape having a thickness of 0.1 to 0.8 mm and a ratio (W / t) of width (W) to thickness (t) of 2 to 4. Eggplant is preferably used.

The crimping rate in the corrugating of the flat wire (1) is related to the wave pitch (P) shown in FIG. 3 and the amplitude (α) at the center line of the thickness. As shown, as the wave pitch (P) and the amplitude increase, the crimping rate increases. However, from the viewpoint of maintaining the elongation rate and the strength at the time of cutting during use, the reinforcing material obtained by the following equation is used. It is preferable that the crimp ratio as a whole is set to 2.0% or less, so that excessive flexibility and elongation do not occur.

Crimp rate (%) = 100 (BA) / A where A: weight per unit length when straight (g /
m) B: Weight per unit length after crimping (g / m) Also, as the above-mentioned corrugating, either one or both of the amplitude (α) and the pitch (P) are regularly changed, By changing it irregularly, it is also possible to carry out a plurality of portions having different crimp rates, for example, a large wave portion and a small wave portion alternately and continuously.

FIG. 5 shows a rubber material (5) obtained by arranging a large number of reinforcing materials in which the surface of a flat wire (1) is formed into an uneven surface (4).
2 shows an enlarged cross section of the sheet body (10) covered with. Regardless of which reinforcing material is used, the flat wire (1) and the rubber have good adhesion and fatigue resistance due to the increase in surface area due to the formation of the uneven surface (4) (4a). And the peel resistance is improved.

The above-mentioned sheet member (10) is used by being embedded in a rubber material as a belt layer of a tire, a reinforcing layer of a sidewall or a reinforcing layer of a bead portion. For example, as shown in FIG. 11, a pneumatic tire (T) such as a radial tire is formed using a belt layer of the tire. In FIG. 11, (21) is a belt layer, (22) is a belt end reinforcing layer, (1)
1) shows a carcass, (12) shows a tread, (13) shows a bead portion, and (14) shows a sidewall.

The pneumatic tire thus configured can secure steering stability and contribute to performance improvement such as durability by improving fatigue resistance and peeling resistance by using the reinforcing material.

[0035]

EXAMPLES Example 1 A flat wire rod having a width of 0.4 mm and a thickness of 0.177 mm was used as a raw material, and a groove having an angle of 0 ° with respect to the longitudinal direction and a depth of 19 microns was formed on both front and back surfaces by rolling a groove roll. , And a corrugation process in which the wave pitch (P) and the amplitude (α) are set as shown in Table 1 below is performed to form a reinforcing material as shown in FIG. 1 and the surface area (S) of the reinforcing material (Example 1) with a surface area ratio (S / Sa) of 1.5 to the surface area (Sa) before providing the unevenness, and a reinforcing material with the surface area ratio of 2.5 (Example 2). And got.

Each of the reinforcing members of Examples 1 and 2 was driven at a number of 50/25 mm and the thickness was 1 mm.
And a sheet body as shown in FIG. 5 was produced.
This sheet was examined for dynamic peeling life by the following method. Table 1 shows the results.

Further, the sheet bodies using the reinforcing members of Examples 1 and 2 were each replaced with a tire size of 195 / 55R1.
6 as the two belt layers of the radial tire having an intersection angle of 23
° at high speed durability. The results are shown in Table 1 below.

Examples 3 and 4 A flat wire having a width of 0.4 mm and a thickness of 0.177 mm was used as a raw material, and was subjected to corrugation processing in which the wave pitch (P) and amplitude (α) were set as shown in Table 1 below. The surface of the flat wire was subjected to sand blasting to form fine irregularities having an irregularity difference of 3.5 microns to form a reinforcing material as shown in FIG. 4, and the surface area (S) of the reinforcing material and the surface area (Sa) before the irregularities were formed. Reinforcing material with surface area ratio (S / Sa) of 1.5 (Example 3)
And a reinforcing material having the surface area ratio of 2.5 (Example 4).

Each of the reinforcing members of Examples 3 and 4 was driven at a number of 50/25 mm and the thickness was 1 mm.
The sheet body was manufactured by embedding in the rubber of No. 1 and the dynamic peeling life of this sheet body was examined in the same manner as described above. Also,
Each of the above-mentioned sheet bodies was used for two belt layers of the same tire as in Examples 1 and 2 at an intersection angle of 23 °, and high-speed durability performance was examined. Table 1 shows the results.

[0040] The sheet member where the steel cord of the conventional twisted structure has the constitution according embedded in rubber material to Comparative Example 1 in Table 1, along with examining the same dynamic flaking life, two layers of the tire of this sheet The high-speed durability when used for the belt layer of Example 1 was examined.
Table 1 shows the results.

Comparative Examples 2 and 3 A flat wire having a flat shape similar to that of the embodiment was used as the material, and the surface was subjected to corrugation with the same wave pitch and amplitude as in the embodiment. Regarding a reinforcing material having a 2.5-micron unevenness (Comparative Example 2) and a reinforcing material in which the surface of the material was polished to remove unevenness (Comparative Example 3),
In the same manner as in the above-described examples, sheet bodies embedded in rubber materials were produced. The dynamic peel life of these sheets was examined, and the high-speed durability when these sheets were used for two belt layers of a tire similar to the above was examined. The results are shown in Table 1.

Comparative Examples 4 and 5 Reinforcers having basically the same structure as in Example 1 and having a surface area ratio of 1.2 (Comparative Example 4) and a reinforcement having a surface area ratio of 3.3 (Comparative Example 5) In the same manner as in Example 1, a sheet body embedded in a rubber material was prepared, and the dynamic peeling life of the sheet body was examined. The durability was examined. The results are shown in Table 1.

With respect to the above-mentioned dynamic peeling life, the two sheets were vulcanized and integrated in a state where the two sheets were bonded together so that the reinforcing members of the two sheets were parallel to each other. A 10 kg load was applied to one of the sheets so that the body could be peeled off, and the eccentric cam connected to the other sheet caused rotation to cause dynamic peeling, and the time until 10 cm was peeled was examined.

As for high-speed durability, FMVSS109
The test was performed in accordance with the prescribed test method, and the time until the failure occurred was examined.

The above evaluations of the dynamic peeling life and the high-speed durability are all expressed as indices with the case of Comparative Example 1 using a conventional twisted steel cord as 100, and the larger the numerical value, the better. Is shown.

[0046]

[Table 1]

As is clear from Table 1 above, even when the material was a corrugated flat wire, the surface of which had a difference of less than 3 microns (Comparative Example 2).
Both the dynamic peel life and the high-speed durability are considerably lower than in the case of Comparative Example 1 using a conventional steel cord, and the reinforcing material of Comparative Example 3 in which a flat wire is polished to remove irregularities is also dynamic. Although the typical peeling life and high-speed durability were better than Comparative Example 2, they were inferior to Comparative Example 1.

Even if the surface of the flat wire material subjected to the corrugation processing is formed with irregularities, the surface area ratio (S / Sa) to the surface area before the irregularities are formed is less than 1.3 ( The results of Comparative Example 4) and those exceeding 3.0 (Comparative Example 5) were also inferior to those of Comparative Example 1 using a twisted steel cord.

On the other hand, in all of Examples 1 to 4 of the present invention, the dynamic peeling life and the high-speed durability were improved as compared with the conventional steel cord having a twisted structure.

Next, the reinforcing members having basically the same structure as the reinforcing members of Examples 1 and 2 described above, and in which only the angle of the groove with respect to the length and direction of the wire is changed, are respectively embedded in the rubber material. When a sample of the same sheet body as in Example 1 was prepared and its fatigue life was examined, results as shown in FIGS. 7 and 8 were obtained, respectively. Further, a tire (size: 195 / 55R16) using the same sheet member as described above using a belt layer (two-layer belt, crossing angle: 23 °) was subjected to a rough road running test. The result was obtained.

In the fatigue life test, the sample is defined in the section of fatigue strength in 2 of JIS L1017 “Test method for chemical fiber tire cord” reference 1 (1).
According to the method based on the Firestone Act (A Act), 40
A kgf force was repeatedly applied, and the number of cycles until the sample was broken was counted.

[0052]

[Table 2]

As a result of this test, the angle of the groove was 45
It was found that the fatigue life and the rough road running performance were sharply reduced when the temperature exceeded 0 °. Therefore, when a groove is formed on the surface of the flat wire (1) to form an uneven surface, the angle is 0.
It is preferable to set the angle in the range of up to 45 °.

The dynamic peel life and fatigue life were tested for a structure basically the same as that of the above-mentioned Example 1 except that the unevenness of the surface of the wire was changed, that is, the depth of the groove formed by the grooving roll was changed. Was performed, the results of FIGS. 9 and 10 were obtained.

From the test results, it can be seen that the peeling resistance does not cause any problem even if the difference between the irregularities is large, but the fatigue life sharply decreases when the difference between the irregularities exceeds 1/5 of the thickness of the wire. Therefore, it is understood that the difference between the irregularities should be set to 3 μm or more and 1/5 or less of the wire thickness.

[0056]

As described above, according to the tire reinforcing material of the present invention, the surface of the corrugated flat wire is formed into an uneven surface that satisfies a specific condition. Without losing the properties, the adhesive strength with rubber can be sufficiently ensured, and the dynamic peeling performance, fatigue resistance and high-speed durability when used for a reinforcing layer of a tire can be improved.
Therefore, the pneumatic tire using the reinforcing material can sufficiently exhibit the effect of using the reinforcing material made of the corrugated flat wire, and has excellent steering stability.
Moreover, the tire has excellent durability.

[Brief description of the drawings]

FIG. 1 is a partially enlarged perspective view showing one embodiment of a tire reinforcing material of the present invention.

FIG. 2 is an enlarged cross-sectional view of the reinforcing member.

FIG. 3 is a side view of a part of the tire reinforcing member.

FIG. 4 is a partially enlarged perspective view showing another embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a part of a sheet body as a reinforcement in which the tire reinforcing material is embedded in a rubber material.

FIG. 6 is a graph showing a relationship between a wave bitch, an amplitude, and a crimp ratio.

FIG. 7 is a graph showing the results of a fatigue life test when the angle of the groove in Example 1 was changed.

FIG. 8 is a graph showing the results of a fatigue life test when the angle of the groove in Example 2 was changed.

FIG. 9 is a graph showing the results of a dynamic peel life test in Example 1 when the unevenness difference was changed.

FIG. 10 is a graph showing a result of a fatigue life test in Example 1 in which a difference in unevenness is changed.

FIG. 11 is a schematic sectional view of a tire using the reinforcing material of the present invention.

[Explanation of symbols]

 (1) Reinforcing material (2) Groove (3) Convex portion (4) (4a) Uneven surface (5) Rubber material (21) Belt layer (22) Belt end reinforcing layer

Claims (6)

[Claims] 1. A corrugated flat wire having a flat cross section, wherein at least one of the front and rear surfaces of the flat wire is formed on an uneven surface having an unevenness of 3 μm or more. The ratio of the surface area to the surface area is 1.3 to 3.0.
A tire reinforcing material characterized by the following. 2. The uneven surface according to claim 1, wherein the concave and convex surfaces are formed by forming grooves at a required interval of 0 ° to 45 ° with respect to the longitudinal direction of the flat wire. Tire reinforcement. 3. The reinforcing material for a tire according to claim 1, wherein the uneven surface has irregularities in which one or both of fine concaves and convexes are formed in a scattered manner. 4. The tire reinforcing material according to claim 3, wherein fine irregularities are formed over the entire surface by sandblasting. 5. A crimping rate of the reinforcing material as a whole determined by the following formula, which is 2.0% or less by corrugation.
5. The reinforcing material for a tire according to any one of items 4 to 4. Crimp rate (%) = 100 (BA) / A where A: weight per unit length when straight (g / g)
m) B: Weight per unit length after crimping (g / m) 6. A pneumatic tire using the tire reinforcing material according to claim 1 for at least one reinforcing layer.