JPH08325966A - Metallic cord and rubber composite - Google Patents

Abstract

PURPOSE: To obtain a compact metallic cord for rubber reinforcement with double-stranded structure excellent in resistance to corrosion and fatigue and enabling both lightweightness and durability improvement of tires, conveyer belts, high-pressure hoses etc. CONSTITUTION: Two metallic filaments 1 are stranded following reforming, and in the stranded state, the two metallic filaments are provided, other than the above reforms, with helical reforms differing in direction from each other with pitches 0.2-0.50 times and 0.33-0.90 times the cord-stranded pitches and the filament radial heights of 0.05-0.25mm and 0.07-0.30mm, respectively. The resultant metallic cord, because of absorbing external energy by virtue of spring effect owing to the fine reforms provided on the respective metallic filaments and thereby relaxing external force applied on the filaments, improves its fatigue resistance against repeated simple flexes and compressive flexes. Besides, there occurs no sheet curling during the calendering process for arranging the reinforcing material in parallel with one another in tire manufacturing process and rubber penetrates through the gaps among the contact points of the respective filaments; therefore, rubber covering rate is raised, and also the corrosion resistance of this metallic cord is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal cord for reinforcing a rubber article having excellent corrosion resistance and fatigue resistance, and a rubber such as a tire, a conveyor belt, a high pressure hose, etc., which is embedded in rubber as a reinforcing material. Regarding composites.

[0002]

2. Description of the Related Art Metal cords used for reinforcing rubber articles are usually made of high-carbon steel wire (JIS G3502 piano wire) and have brass, copper, zinc, etc. on the surface to provide adhesion to rubber. Is metal-plated and wire-drawn to a diameter of 0.1 to 0.5 mm, then single-twisted, double-twisted, or layer-twisted, widely used as a reinforcing material for automobile tires, conveyor belts, high-pressure hoses, etc. Has been. For example, radial tires for passenger cars use a metal cord having a 1 × 4 or 1 × 5 single twist structure in which four or five metal filaments are twisted together as a belt portion reinforcing material.

Quality characteristics required of the metal cord as the rubber reinforcing material include adhesiveness with rubber, corrosion resistance, fatigue resistance, and various other mechanical performances (cutting load, rigidity, etc.). . Among these, regarding corrosion resistance, when the rubber uncovered part is present in the metal cord embedded in rubber, when the tire is stepped on stones, nails, etc. while running, the scratch reaches the metal cord The cords corrode within a short period of time due to the moisture penetrating through the scratches, and the cutting load and fatigue resistance of the cords deteriorate. Further, the adhesion between the cord and the rubber may be deteriorated, and the cord may be peeled off to cause quality trouble due to separation of the tire.

The above-mentioned 1 × 4 or 1 × 5 closed cord, which is generally used, has a cross-sectional shape as shown in FIG. 4 and has a cavity at the center of the cord. For this reason, when these metal cords are embedded in rubber, the rubber does not penetrate into the cord, and a hollow space where the rubber is not coated is generated. Such a composite of a metal cord and a rubber having a hollow space inside has a short service life because it causes quality troubles such as corrosion of the metal cord and separation of the metal cord and rubber due to permeation of water.

In order to solve this problem, for example, Japanese Patent Laid-Open No. 55-90692 proposes an open cord in which metal filaments 2 are twisted so that there is a gap between them, as shown in FIG. Japanese Patent Publication 58-31438
In the publication, as shown in FIG. 6, a 2 (parallel) +2 cord having almost no void inside the cord is proposed, and both of them have already been put into practical use as a reinforcing material for tires.

Further, in Japanese Patent Laid-Open No. 2-307994, at least one filament among three or more metal filaments is passed between the tooth flanks of a pair of meshing gears to be staggered in a zigzag shape. After that, we have proposed to improve the rubber permeability by twisting and gaps provided between filaments, but this method concentrates stress on the tooth profile near two-dimensional imparted to the metal filament, and fatigue resistance is improved. Markedly reduced. Actual public Sho 60-6475
Japanese Patent Publication also proposes an inexpensive metal cord in which spirally curled metal filaments are bundled in parallel with a wrapping wire to create a gap between the filaments, but this is not twisted and therefore flexible. However, there is a drawback in that the moldability during tire production and the riding comfort during tire running are poor. In addition, Japanese Examined Japanese Patent Publication 63-632
Japanese Unexamined Patent Publication No. 93 discloses a metal cord having a two-layer twist structure in which six filaments twisted in a spiral shape are twisted around a non-twisted core having two twists. Since it has a large number of twists, it is not suitable for reducing the weight of automobile tires, leading to an increase in cost, and there is also a problem in terms of quality because untwisted double-stranded strands are used as the core.

On the other hand, from the viewpoint of reducing rolling resistance and weight, there is a strong demand for weight reduction, and the twisted construction of the cord is simple so that the diameter of the metal cord can be reduced and the thickness of the covering rubber can be reduced. Attempts have been made to realize this. For example,
Japanese Patent Laid-Open No. 62-117893 and Japanese Patent Laid-Open No. 62-234
Japanese Patent No. 921 proposes a very simple 1 × 2 cord in which two metal filaments 2 are twisted together as shown in FIG. Since this cord does not have a cavity inside, the cord is covered with the embedded rubber except the filament contact portion, and has an excellent corrosion resistance. Further, in Japanese Patent Laid-Open No. 2-229286, by setting the degree of twisting and stiffening of two metal filaments in an appropriate range, a gap is partially provided between the two metal filaments, and thereby, the rubber coating is performed. A 1 × 2 improved code has been proposed which further improves the corrosion resistance and corrosion resistance.

However, when a 1 × 2 cord is used instead of the above 1 × 4 cord or 1 × 5 cord, in order to compensate for the reduced number of twists in consideration of the cutting load and rigidity of the metal cord. A filament having a large diameter is used. The 1 × 2 code is (b-b), (c) in FIG.
As can be seen from -c), the cross section of the cord has a form in which the metal filaments 2 are arranged horizontally or vertically, and has a nonuniform structure with large irregularities in the longitudinal direction.

Thus, the diameter of the filament is large,
Further, if the structure is non-uniform in the longitudinal direction, the fatigue resistance (bending fatigue and compression fatigue) of the cord deteriorates. In particular, when it is used for a belt portion of a passenger car tire, compressive stress is repeatedly applied to the metal cord due to the buckling phenomenon of the tire belt portion that occurs during rapid turning, but the compressive fatigue resistance to this repeated buckling phenomenon is poor. There's a problem. Therefore, in order to solve such problems,
As disclosed in Japanese Unexamined Patent Publication No. 5-230780, the present inventors twist two metal filaments and, in the twisted state, cause two metal cords to have a spiral habit in addition to the twist habit. By doing so, a metal cord that has improved corrosion resistance and a lightweight 1 × 2 cord that has improved fatigue resistance such as bending fatigue and compression fatigue, and a tire and a conveyor belt that have improved durability using this cord as a reinforcing material, Composites such as high pressure hoses have been proposed.

[0010]

However, the above-mentioned Japanese Unexamined Patent Application Publication No.
Since the metal cord disclosed in Japanese Patent Laid-Open No. 230780 is not as open as the open cord shown in FIG. Since the sheet is pulled by applying a tension of about 2 kgf, it is desired to improve the sheet curl due to the occurrence of residual torsion (the same direction as the spiral wave winding direction) due to stretching.

[0011]

In order to solve the above-mentioned problems, the present invention is a metal cord formed by twisting two metal filaments, wherein both metal filaments are twisted in a twisted state. Besides, it has a fine spiral wave-like habit, and the winding directions thereof are different from each other. Since the winding directions are different from each other, when the metal cord formed by twisting two metal filaments together is stretched and stretched, the twisted metal cord itself has a function of reducing the force to rotate. The spiral wave shape after the twisting of the two metal filaments has a corrugation pitch p _s of 0.20 to 0.50 times the cord twist pitch P and a wave height h _s of 0. 05
On the other hand, the corrugation pitch p _z is 0.33 to 0.90 times the cord twist pitch P, and the wave height h _z is 0.07 to 0.30 mm. In the spiral wave shape of both metal filaments after the cords are twisted, the difference in corrugation pitch of both metal filaments | p _z −p _s | is 5 mm or less, and the difference in wave height | h _z
It is desirable to regulate −h _s | to 0.10 mm or less.

In such a metal cord, before being twisted, the pitch p ₁ is preferably 0.25 to 1.0 times the cord twisting pitch P and the wave height h is set to each of the metal filaments.
₁ is 0.18 to 0.50 mm and the winding directions of the waves are different from each other, and then the two metal filaments have pitch p _{1 at the} above-mentioned p _s and p _z and height h ₁ is It is obtained by twisting so as to change to the above-mentioned h _s and h _z , respectively. The diameter of d _s of both metal metallic filament filament diameter is the same as the direction winding direction of the spiral wave twisted cord, if it the diameter of the metal filaments are opposite and d _z, d _z ≦ d _s It is preferable that the relationship of ≦ 1.2d _z is satisfied. The above metal cords are
It is desirable to twist them with a double twisting wire machine.

A tire, a conveyor belt, a high-pressure hose, etc. made by embedding such a metal cord as a reinforcing material in rubber mainly composed of natural rubber or synthetic rubber is the composite of the present invention, and the composite is the same. It is more durable than conventional composites that use two-strand cords. On the surface of the metal filament, in order to improve adhesion with rubber,
It is desirable to coat brass, copper, zinc or brass with a metal plating such as a ternary alloy containing an element such as Co, Ni or Sn.

As described above, the metal cord of the present invention in which two metal filaments are twisted together and in which the two metal cords in the twisted state have a spiral wave-like habit in addition to the twisted habit, are disclosed in the above-mentioned Japanese Patent Laid-Open No. 5-58. As disclosed in US Pat. No. 230,780, for example, a plurality of pins to be habited before twisting are individually added by adding spiral undulations to each other by rotating them around the longitudinal central axis of the filament, It can be relatively easily manufactured by a method of twisting two filaments marked with.

[0015]

The metal cord of the present invention, as shown in FIG.
Since the metal filaments 1-s and 1-z of the book are twisted together, the cord twist pitch is smaller than the cord twist pitch, and they have spiral wave-like habits different from each other in the winding direction, for example, a tread portion of a passenger car tire. When used as a reinforcing material on a metal filament, even if the cord is subjected to simple bending or compression bending due to bending deformation on rough roads or buckling deformation due to buckling phenomenon during rapid turning It has the function of absorbing external energy by the spring effect of the spiral wave habit and relaxing the external force applied to the filament,
Fatigue resistance to repeated simple bending or compression bending is improved, and since spiral waves in different directions are applied to both metal filaments, the occurrence of sheet curl can be eliminated.

Further, since the cord of the present invention has a small spiral wave-like habit, it exhibits a discontinuous contact form, and since the rubber penetrates through the gaps between the filaments, the rubber coverage is good. Therefore, it is possible to further improve the corrosion resistance, and there is also an advantage that the fretting wear is reduced because the contact portions between the filaments are very small.

Furthermore, since the metal cord of the present invention is designed so that the spiral wave shape applied to both metal filaments does not change significantly, fatigue resistance and corrosion resistance are improved, and durability of rubber articles is improved. Excellent effect for improvement.

The reason for limiting the numerical values of both metal filaments will be described below regarding the spiral wave-like behavior in the twisted state. The metal filament 1-s whose wave winding direction is the same as the cord twisting direction has a pitch p _s of 0.20 to 0.50 times the cord twisting pitch P and a wave height h _s of 0.05 to. Although 0.25 mm, if the pitch p _s is too large, when the cords are twisted together, the winding direction of the wave is the same as the twisting direction, so the filaments are twisted and tension is added, while various types of tension are applied. The habit tends to disappear due to frictional resistance with the guide, etc., and the effect of improving fatigue resistance diminishes. On the other hand, if the pitch p _s is too small, the amount of twist added to the metal filaments will be large and the cord strength will be significantly reduced, or the inter-filament gap will be too small and the rubber permeability will be reduced. The above range was selected as a preferable value in order to avoid these problems.

Further, as the height h _{s of the} wave increases, the relaxation effect against external force also increases and it is effective in improving the fatigue resistance. Therefore, the size of the gap through which the rubber can penetrate between the metal filaments having the wavy habit. However, if the wave height h _s is too large, the diameter of the cord will become large, and it will be difficult to maintain the twist uniformity of the cord. The upper limit was determined from the case where the corrugated pitch with respect to the twist pitch of the cord was set in the above range by using the metal filament in the above range.

Next, the metal filament 1-z whose wave direction is opposite to the cord twisting direction has a pitch p _z of 0.33 to 0.90 times the cord twisting pitch P and a wave height h _z. Although the pitch is set to 0.07 to 0.30 mm, the pitch p _z is set to be larger than the pitch p _{s in} a direction in which the twist is untwisted when the cords are twisted even if the corrugated shapes given in advance are the same. Therefore, the pitch of the wave becomes large, but the tension is not applied as much as in the case of the filament 1-s, so that the height of the wave remains relatively large. As described above, the above numerical values were decided in consideration of the difference in the winding direction of waves.

As described above, the spiral waves applied to both filaments have different winding directions, and one is the same as the cord twisting direction and the other is the opposite direction. Differences are likely to occur, but it is important to match as much as possible, and as a result of various studies from this point,
The difference in pitch is 5 mm or less, and the difference in wave height is 0.10 mm
It was necessary to regulate the following.

On the other hand, in order to allow a small spiral wave-like habit to remain in the twisted state and facilitate rubber penetration between filaments, it is important to preliminarily apply the spiral wave-like habit.
The corrugation pitch p ₁ before twisting is set to 0.25 to 1.0 times the cord twisting pitch P, but the lower limit does not reach the processing limit due to the twist added to the filament 1-s when twisting the cords. Therefore, the upper limit is set to the above range in consideration of the corrugated pitch at which the filament 1-z does not disappear due to the additional tension at the time of twisting the cords and the frictional resistance with various guides. Further, the wave height h ₁ is set to 0.18 to 0.50 mm, but if the peculiar pitch is decreased in the twisting process, the additional tension and frictional resistance with various guides are increased, while the peculiar pitch is increased. In this case, the wave shape is more likely to disappear near the upper limit of p _z , so these were taken into consideration for the determination. The shape of the spiral wave is defined as shown in FIG.

By the way, both metal filaments are different in the winding direction and shape of the spiral wave for the above-mentioned reason, but in particular, the corrugation pitch of the filament 1-s is easier to reduce, and the fatigue resistance is correspondingly increased. Because it works against you,
Because keep the same with a difference in filament diameter is efficient, pitch and height of the spiral waves even in consideration, the diameter of the metal filaments is the same as the direction winding direction of the spiral wave twisted cord d _s it when the diameter of the metal filaments are opposite and d _z, may to satisfy following _{d z ≦ d s ≦ 1.2d z} . The spiral wave applied to both filaments (particularly filament 1-s) by the cord twisting tends to disappear as described above when the cord twisting pitch P is too small. Therefore, a reasonable value is 10 mm or more and 20 mm or more. The following was set (preferably 12 mm or more and 18 mm or less). Also, like the code of the present invention,
Since the × 2 structure has emerged as an inexpensive cord, it occurs when twisted by twisting with a double twisting and twisting machine (which can twist twice in one rotation) boasting high productivity. It is preferable to reduce the cost, and the code of the present invention was developed on the assumption that the cost is reduced.

[0024]

EXAMPLE Two brass-plated metal filaments having diameters of 0.31 mm and 0.29 mm were twisted together at a twist pitch of 14 mm by using a double twisting and twisting machine to obtain a 1 × 2 structure as shown in FIG. A cord 3 with a spiral wave was produced (Example 1). In this cord, the two metal filaments 1-s and 1-z in the twisted state are
Each has a wavy pitch of 4.7 mm (0.34P) and 5.6 mm (0.40P), and wave heights of 0.10 mm and 0.14 mm, creating a double spiral. Has become. In other words, both metals filaments Egaki a spiral in opposite directions at a period smaller than the code twist pitch and inscribed in a circle of diameter d ₁ and d _2, whereas, the circle of diameter d ₁ and d ₂ determines the code size diameter Since both of the filaments are inscribed in the circle of D to form a spiral with the same cycle as the twist pitch of the cord (here, 14 mm), both filaments form a double spiral. The spiral winding direction of the metal filament 1-s having a diameter of 0.31 mm (large diameter) is S winding in the same direction as the twisting direction (S), and the diameter of the metal filament is 0.29 mm (small diameter). That of 1-z is Z winding.

Further, while using the same metal filament, metal cords (Examples 2 and 3 and Comparative Example 1) in which the spiral wave shape after twisting was changed little by little were produced, while intentionally after twisting. The difference in corrugation pitch | p _z −p _s | is 5 mm
(Comparative example 2) and cord twist pitch exceeding 1
A cord (Comparative Example 3) having a length of less than 0 mm (here, 9 mm) was also manufactured.

Further, by using two metal filaments having a diameter of 0.30 mm, a cord having the same twist pitch (14 mm) and twist direction as in Examples 1 to 3 and having substantially the same wave shape (Example) 4 to 6) while producing a cord having a difference in corrugation pitch after twisting of more than 5 mm as in the cord of Comparative Example 2 (Comparative Example 4) and JP-A-5-23.
A cord (Comparative Example 5), which is found in Japanese Patent Publication No. 0780 and in which the spiral direction applied to both metal filaments was the same as the cord twisting direction, was also prepared.

Next, using the above filaments of different diameters,
A cord (Comparative Example 6) in which the spiral waves were wound in the opposite direction to that of Example 1 was prepared. In addition, cords (Example 7 and Comparative Example 7) in which the filaments of both filaments were largely shaken to be twisted together were also produced. As a base cord, a compact cord (C · C) 4 having a conventional 1 × 2 × 0.30 structure shown in FIG. 2 was also prepared.

Using the above samples, the sheet curl characteristics were investigated by a simulated line of the calendar process for aligning the reinforcing materials at the time of tire production, while the rubber coating when embedded in rubber which is a substitute characteristic of corrosion resistance. The modulus was measured, and a cord axial compression fatigue test was performed on a cord / rubber composite as a substitute property of fatigue resistance. Table 1 shows the results.

[0029]

[Table 1]

As can be seen from Table 1, the cords of Examples 1 to 7 have improved rubber permeability and have a very good rubber coverage as compared with the cords of Comparative Examples 1 and 3. Further, the fatigue resistance of the cord / rubber composite in the compression fatigue test was superior to that of Comparative Examples 1 to 4 and Comparative Examples 6 and 7, and the sheet flatness of the composite was also Comparative Example 5. It can be said that it is better than 7.

[0031]

As described above, the metal cord of the present invention is composed of two metal filaments having fine spiral wave-like habits whose directions after twisting are different from each other. In addition to selecting the wire diameter, the cord twist pitch is optimized so that the spiral wave does not disappear, so there is no sheet curl, it is easy to use, fatigue resistance due to compression bending is improved, and it is provided between filaments. The gap improves the rubber coverage and is effective in improving corrosion resistance and reducing fretting wear. Therefore, the compound such as the tire, the conveyor belt, and the high-pressure hose composed of the metal cord and the rubber described above can have improved fatigue resistance and corrosion resistance, improved durability, and can be reduced in weight.

[Brief description of drawings]

FIG. 1 is a view showing an example of a metal cord of the present invention,
(A) shows the appearance, bb shows the cross section of the bb line part of (a), and cc shows the cross section of the cc line part.
Moreover, (b) represents the winding direction of the spiral wave.

FIG. 2 is a view showing a conventional two-strand compact cord, (a) is an external appearance, bb is a cross section of a bb line portion of (a), and cc is a cc line. The cross section of the part is shown.

FIG. 3 is a plan view of a metal filament having a spiral wave-like habit.

FIG. 4 is a cross-sectional view (a) of a 1 × 5 closed cord,
Sectional drawing (b) of 1x4 closed cord.

FIG. 5 is a cross-sectional view of a 1 × 5 open cord.

FIG. 6 is a sectional view of 2 (parallel) + cord.

[Explanation of symbols]

1: Small spiral wavy metal filament (1-s: Metal filament whose wave winding direction is the same as the cord twisting direction) (1-z: Metal whose wave winding direction is opposite to the cord twisting direction) (Filament) 2: Small spiral wavy metal filament that is not imprinted 3: Corrugated metal cord (S / C) 4: Metal cord (C / C)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B60C 15/04 C08J 5/04 CEQ C08J 5/04 CEQ 7310-4F B29C 67/14 X // B29K 21:00

Claims (9)

[Claims] 1. A metal cord formed by twisting two metal filaments together, wherein both metal filaments have a fine spiral wave-like habit in addition to the twist habit in the twisted state, and A metal cord characterized by different winding directions. 2. A spiral wave-shaped habit other than the twisted habit in the twisted state of both metal filaments, one of which has a corrugation pitch p _s of 0.20 of a cord twist pitch P.
0.50 times, wave height h _s is 0.05 ~ 0.25mm
In the other, the same pitch p _z is 0.3 of the cord twist pitch P.
3 to 0.90 times, wave height h _z is 0.07 to 0.30 m
The metal cord according to claim 1, which is in the range of m. 3. The difference in the corrugation pitch | p _z −p _s | in the twisted state of the two metal filaments is 5 mm.
The metal cord according to claim 2, wherein: 4. The difference in wave height | h _z −h _s | in the twisted state of both metal filaments is 0.10 m.
The metal cord according to claim 2, wherein the metal cord has a length of m or less. 5. The spiral wave-like habit applied before twisting the both metal filaments has a corrugation pitch p ₁ of 0.25 to 1.0 times the cord twist pitch P and a wave height h ₁ of The metal cord according to any one of claims 1 to 4, wherein the winding directions of the waves are different from each other at 0.18 to 0.50 mm. 6. In both the metal filaments, the diameter of the metal filament in which the spiral wave winding direction is the same as the cord twisting direction is d _s , and the diameter of the metal filament in the opposite direction is d _z , d _z ≦ The metal cord according to claim 1, which satisfies the relationship of d _s ≦ 1.2 d _z . 7. The metal cord according to claim 1, wherein the twist pitch P of the cord is 10 mm or more. 8. The metal cord according to claim 1, wherein the two metal filaments are twisted together by a double-twisting machine. 9. A rubber composite, such as a tire, a conveyor belt, a high pressure hose, which is obtained by embedding the metal cord according to claim 1 in a rubber mainly composed of natural rubber or synthetic rubber as a reinforcing material.