JP3349446B2 - Metal cord and pneumatic tire using the same - Google Patents

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 rubber, which can increase rubber permeability into filaments while reducing the cord diameter, and a pneumatic tire using the same.

[0002]

2. Description of the Related Art A metal cord formed by twisting a plurality of metal filaments is often used for various rubber materials, for example, a belt layer of a pneumatic tire. As such a metal cord, for example, as shown in FIG. 10, a compact cord a or the like twisted without forming a gap between the metal filaments f, f is used.

However, such a compact code a
Then, although the filaments f, f are subjected to surface plating, a space is formed between the filaments f, f where rubber cannot penetrate, so that rust in the cord is affected by moisture. This causes problems such as generation or spreading, and a decrease in the adhesive strength between the cord and the rubber, a decrease in the strength of the cord, and a break in the cord.

In recent years, in order to improve the rust problem of the metal cord, as shown in FIG. 11, a so-called open cord b twisted so that a gap is generated between the metal filaments f, and FIG. As shown, by twisting the three-dimensional spiral shaped molding filament f1 and the non-molding filament f2, a gap is formed between the metal filaments to increase the rubber permeability inside the cord. Code c and the like have been proposed.

However, the cords b and c shown in FIGS. 11 and 12 have a disadvantage that the cord diameter naturally increases in order to ensure a sufficient rubber permeability.

The present invention has been devised in view of such a situation. A plurality of filament bundles are formed by bundling two to three molding filaments including two or more types and twisting them at a relatively long pitch. In addition, based on twisting these filament bundles while twisting them at a predetermined final twist pitch, a metal cord that can secure rubber infiltration between filaments while keeping the cord diameter compact, and a pneumatic cord using it It is intended to provide tires.

Further, the present invention limits the wave height, wave pitch, etc. of the shaping applied to the filament before twisting to a specific range with respect to the filament diameter.
It is another object of the present invention to achieve both a reduction in strength of the finally twisted cord and a rubber penetration property.

[0008]

According to a first aspect of the present invention, there is provided an n-type cable having a wire diameter d of 0.30 to 0.45 mm.
(N = 8, 9, 10) , and all the metal filaments have a two-dimensional wavy shape having a straight portion between a wave crest and a valley before being twisted. Consisting of a molding filament molded into
And the shaping filament has at least the wave pitch P
While two or more types of shaping filaments having different w are included, the shaping wave pitch Pw and the wave height h of the different types of filaments are the same, and the wire diameter d, the shaping wave pitch Pw, and the wave height of the shaping filament are the same. H
Satisfies the following relationship: 5.0d ≦ Pw ≦ 30.0d 0.2d ≦ h ≦ 3.0d 0.014 ≦ d × h / Pw ≦ 0.028 Pw: Wave pitch (mm) h: Wave height of the forming filament (mm) d: Wire diameter of the forming filament (mm) Two to three of the above-mentioned forming filaments including two or more types are bundled and the final twist pitch Pc is three to three. A plurality of filament bundles are formed by being twisted at a pitch Pf of 20 times, and the filament bundles are formed into the following i ) to
vi ) and twist pitch Pc
This is a metal cord having a length of 10 to 40 mm. i) when n = 8, consisting of two different shaped filaments
Two filament bundles 4 ii) the same typed filaments of two and one different pins
3-filament bundle consisting of staple shaped filaments
Two and two different shaped filaments
When one bundle of two filaments consists of n = 9 iii) It consists of two different shaped filaments
Three bundles of two filaments and two identical molds
Lament and one different pitch molding filament
One iv) and the same typing filaments of the two three filament bundles composed of, different one
Three filaments consisting of pitch forming filaments
3 in a bundle, n = 10 v) Consists of two differently shaped filaments
Vi) two filament bundles vi) two identical shaped filaments and one different
3-filament bundle consisting of staple shaped filaments
Two and two different shaped filaments
Two filament bundles

The invention according to claim 2 is the metal cord according to claim 1, wherein the filament bundle is twisted while being twisted.

According to a third aspect of the present invention, the plurality of filament bundles include at least two or more three-filament bundles composed of three molding filaments therein. It is a metal cord described.

According to a third aspect of the present invention, there is provided a pneumatic tire using the metal cord according to any one of the first to third aspects for a belt layer.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a metal cord for tire reinforcement used for a belt layer of a pneumatic radial tire is illustrated, and the metal cord has a wire diameter d of 0.3.
It is composed of 8 to 10 metal filaments of 0 to 0.45 mm.

Conventionally, metal cords used for belt layers of radial tires for passenger cars include, for example, 1 × 5, 1 ×
Metal cords used for belt layers of heavy duty radial tires used for trucks, buses, etc., have a 3 + 6 configuration (9 total filaments, two types of filaments). (Including diameter), 2 + 7 configuration (9 total filaments,
Many types of filaments (one type of filament diameter), 3 + 9 + 15 (total number of filaments: 27, and one type of filament diameter) have been used.

In general, increasing the filament diameter and reducing the number of filaments is advantageous in terms of cost and productivity in producing a cord. Also, in terms of the performance of the cord, there is an advantage that the smaller the number of filaments, the easier it is to increase the degree of penetration of the rubber into the cord.

Therefore, in the present invention, the above 3 + 9 + 1 which is frequently used for a belt layer of a radial tire for heavy load is particularly used.
8 to 10 metal filaments having a wire diameter d of 0.30 to 0.45 mm ( alternatively to a metal cord having 5 configurations (total of 27 filaments) and being particularly preferably implemented with a reduced number of filaments) If the number is n
, N = 8, 9, or 10) .

The wire diameter d of the metal filament is equal to 0.
In the case of less than 30 mm, for example, if the number of filaments is 8 to 10, it is difficult to obtain the required rigidity as a reinforcing cord material of the belt layer of the heavy duty radial tire, and even if the filament is corrugated as described later. The mold attached before twisting the cord is easy to return to the original state when twisting, and the rubber permeability tends to be insufficient. Conversely, the wire diameter d is 0.45
In the case of exceeding mm, the distortion at the time of applying the wavy molding becomes too large, and the strength of the filament is greatly reduced,
The flexibility of the cord required for tire production cannot be obtained.

Preferably, the metal filament has a surface coated with various kinds of metal or resin, and in the present embodiment, all filaments constituting the cord have the same wire diameter. I have.

Further, as shown in FIGS. 1A and 1B,
Before the metal filaments 2 are twisted, the two-dimensional corrugated molding filaments 2A1, having a straight part 3 between the wave peak U and the valley D, are formed.
2An (hereinafter sometimes simply referred to as “molding filament 2A”).

The shaping filament 2 includes at least two types of shaping filaments 2A1 and 2An having different wave pitches Pw, and in this example, two types of shaping filaments 2A1 and 2An. However, the wave pitch Pw and the wave height h of the shaping for each filament of different types are substantially the same. The wave pitch Pw and the wave height h are measured as shown in FIG.

The reason why all the metal filaments 2 are formed from the molding filaments 2A is that if only a part of the metal filaments 2 is molded, more unmolded non-molding filaments are used. This is because a load may act to cause a problem of reducing the strength of the entire cord.

In the present invention, the molding filament 2A
Is limited to a two-dimensional wavy shape having the linear portion 3, it is easy to form a gap between the filaments. For example, compared to a three-dimensional spiral shaped one, the shaped wave Even if the height h is relatively small, it is possible to sufficiently secure the permeability of the rubber into the cord. Further, even in the case of having a large number of filaments, it is possible to increase the rubber permeability while making the cord diameter compact. If the straight portion 3 is not included in the corrugated shape, the permeability of the rubber into the cord decreases, and the intended purpose cannot be achieved.

Further, when the shaping filament 2A does not include at least two or more filaments having different wave pitches Pw, when a relatively large number of metal filaments of 8 to 10 are twisted, as shown in FIG. For example, the linear portions 3 of the shaping waves of the shaping filaments 2A1 and 2A1 tend to overlap with each other, and this is not preferable because the permeability of rubber is reduced.

As shown in FIG. 2, the metal cord 1 of the present invention bundles two or three shaping filaments 2A including two or more types and forms a final twist pitch Pc of 3%.
A plurality of filament bundles 4 are formed by twisting at a pitch Pf of up to 20 times.
In this example, one of the features is that the wire is twisted and twisted at a twist pitch Pc of 10 to 40 mm.

Thus, prior to the final twisting, 2
By bundling two or three molding filaments 2A containing more than one kind, and twisting and bundling them at a relatively long pitch Pf of 3 to 20 times the final twist pitch Pc,
For example, as shown in FIG.
The metal cord 1 which can effectively prevent the waves of the molding of 2An and 2A1 from overlapping, can form many gaps 5 between the filaments, and can increase the permeability of the rubber into the inside can be obtained. Further, when the filament bundle 4 is twisted while being twisted as in this example, it is preferable in that the cord diameter can be made more compact and the permeability of the rubber into the cord can be further increased.

When the filament bundle 4 is formed by bundling four or more molding filaments, the molding waves of the molding filaments 2A easily overlap as shown in FIG. As a result, the permeability of the rubber decreases, for example, a closed space where the rubber does not penetrate tends to be formed. In addition, filament bundle 4
However, the same problem arises when one type of molding filament 2A is used.

Further, when the pitch Pf at the time of forming the filament bundle 4 is less than three times the final twist pitch Pc, the gap 5 formed in the filament bundle 4 is reduced, and the rubber permeability is reduced. On the other hand, if it exceeds 20 times, the shaping waves of the shaping filaments 2A, 2A tend to overlap each other even when the filament bundle 4 is formed.

In the present invention, the molding filament 2A is
Since 10 to 10 filaments are used, the number configuration of the filament bundle 4 is, for example, as shown in FIGS. FIG. 4 shows an example in which eight molding filaments are used, and FIG. 4A includes four two-filament bundles 4A obtained by bundling the molding filaments 2A1 and 2An one by one.

In FIG. 4B, for example, one of the forming filaments 2A1 and two of the forming filaments 2An having different wave pitches from the filament are bundled.
It includes two filament bundles 4B and one filament bundle 4A. That is, n = 8
Consisting of two differently shaped filaments
4 or 2 same typed filament bundles
And one different pitch typed filament
Two of the three filament bundles and two
1 bundle of two filaments
Twist the books.

FIG. 5 shows an example in which nine molding filaments 2A are used. In FIG. 5A, the filament is composed of one filament bundle 4B and three filament bundles 4A. I have. In FIG. 5B, three filament bundles 4B are included. That is, when n = 9, two
Two filaments made of different shaped filaments
Three bundles of bundles and two identical shaped filaments,
3 strands of one type of filament with different pitch
One or two identically shaped filaments in a filament bundle
And a different pitch of the forming filament
The three filament bundles are twisted.

FIG. 6 shows an example using ten molding filaments. In FIG. 6A, a two filament bundle 4 is used.
A consists of only five lines. In FIG. 6B,
The figure includes two filament bundles 4B and two filament bundles 4A. Immediately
When n = 10, two different typed fillers
Five or two filament bundles
Same type filament and one different pitch type
Two of three filament bundles of filaments, and
Two filaments made of two different molding filaments
Twist two filament bundles. In each filament bundle 4, the number ratio of the molding filaments 2A1 and 2An may be changed, of course, other than the illustrated example.

When the plurality of filament bundles 4 are constructed, as shown in FIGS. 4 to 6B, the three filament bundles 4B including three molding filaments 2A are contained therein. It is particularly preferred that at least two or more filaments are included, whereby the molding filament 2A
This is advantageous in that the shaping waves can be effectively prevented from overlapping, and more gaps can be formed between the filaments.

FIG. 7A is a sectional view of a metal cord 1 composed of nine metal filaments formed by twisting these filament bundles 4A or 4B while twisting them, and FIG. Shows a cross-sectional view of a metal cord 1 composed of eight metal filaments.

As described above, the filament bundle 4 is twisted while being twisted, and the corrugated shape is limited. In this embodiment, the cord diameter can be made more compact and the rubber permeability can be increased efficiently. In addition, the metal cord 1 of the present invention does not need to have a short twist pitch in order to secure a large rubber penetration rate.
The twist pitch is relatively long compared to the filament diameter d of the filament of mm, which is preferable in that the productivity of the cord can be improved.

In the metal cord 1 of the present embodiment, the twisting direction for forming the filament bundle 4 and the final twisting direction are the same, but the intended purpose is achieved even if these directions are reversed. Can.

As a result of various experiments by the present inventors, when a cord having a limited wire diameter d and including a specific number of shaping filaments 2A is manufactured, the wire diameter d of the shaping filament 2 It has been found that it is important that the wave pitch Pw and the wave height h of the shaping satisfy the relationship of the following formulas. 5.0d ≦ Pw ≦ 30.0d 0.2d ≦ h ≦ 3.0d 0.014 ≦ d × h / Pw ≦ 0.028 Pw: Wave pitch (mm) of the forming filament h: Wave height of the forming filament D (mm) d: Wire diameter of the forming filament (mm)

When the shaping wave pitch Pw is less than 5.0 times the wire diameter d of the shaping filament 2 to be used,
The wave pitch becomes too small, and the shaping process causes a large damage to the shaping filament 2A, which causes a decrease in the strength of the filament. Conversely, if it exceeds 30 times,
The wave pitch becomes too small and the permeability of the rubber decreases.

If the wave height h is less than 0.2 times the wire diameter d of the molding filament 2 to be used, it is difficult to increase the rubber permeability, and if it exceeds 3.0 times, The molding process causes a large damage to the molding filament 2A, which causes a decrease in the strength of the filament.

Further, as shown in the above equation, the present inventors examined the relationship between the strength reduction rate (%) of the cord and the rubber penetration rate (%) by variously changing d × h / Pw. d
It was found that a remarkable effect was exhibited by limiting xh / Pw to the range of 0.014 to 0.028.

FIG. 8 shows the relationship among the cord strength reduction rate (%), the rubber penetration rate (%), and the parameter d × h / Pw. As is apparent from this figure, d × h / Pw
It can be seen that the larger the value of, the greater the rate of decrease in cord strength and the worse the performance, but the higher the permeability of rubber. Therefore, in the present invention, the possible range of d × h / Pw is set to 0.
014-0.028, more preferably 0.020-0.028.
By limiting the range to 025, the strength reduction rate of the cord is suppressed within an allowable range, and at the same time, the rubber permeability is increased. The strength reduction rate (%) and rubber penetration rate (%) here are in accordance with the definitions in Examples (described later).

The metal filament 2 is preferably a hard steel wire having a carbon content of, for example, 0.65 to 0.88 wt%. If the carbon content of the metal filament 2 is less than 0.65%, the strength of the filament tends to decrease. Conversely, if the carbon content exceeds 0.88% by weight, the hardness of the filament is too high and the strength decreases greatly during molding. Tend to be.

The metal cords 1 are, for example, a plurality of cords arranged in parallel at equal intervals and covered with a topping rubber or the like to form a rubberized ply. On this occasion,
The number of metal cords included per unit length of the ply in a direction perpendicular to the longitudinal direction of the cords can be variously set according to the specifications of the tire.

If the number of cords per unit length of the ply is too small, the cord arrangement is likely to be disturbed, such as uneven cord spacing during vulcanization molding when used in a tire. If the gap between the cords is too small, the strain generated in the rubber between the adjacent cords due to the running of the tire increases, leading to a decrease in the durability of the tire such as generation of cracks in the rubber layer.

[0043]

EXAMPLES In order to confirm the effects of the present invention, various metal cords were experimentally produced, and the characteristics of the metal cords and the tire performance when the metal cords were used as a tire belt layer were compared and evaluated. The definitions of the terms in the table are as follows.

<Strength reduction rate> A compact twisted at the same twist pitch as the final twist pitch of the metal cord of the present invention using the same composition (the same composition such as carbon content) and the same number of metal filaments. The rate of decrease in strength relative to the code of the structure (hereinafter referred to as “comparison code”),
It is measured in a state before being used for a tire. The smaller the numerical value is, the less the strength decreases and the better.

<Rubber Permeability> A tire having a belt layer using a sample metal cord is manufactured, and the metal cord is removed from the tire with the topping rubber attached. After removing rubber as much as possible from the surface of the rubber cord, a knife is inserted from the cross section to remove two adjacent filaments out of 8 to 10 filaments, and the removed two filaments and the remaining two filaments are removed. The length of the portion where rubber is completely filled in the gap formed between the bundle of filaments is measured over about 10 cm, and the ratio of the length of the portion filled with rubber to the total length is expressed as a ratio of the length of the rubber. Permeability. Perform the above measurement on 10 codes,
The average value is used as the measured value of the code.

<Bending Rigidity of Cord> The bending rigidity of the metal cord was measured using a “V-5 Rigidity Tester” manufactured by Taba (USA).

<Rust generation after running the tire>
After running for 10,000 km, the tires were disassembled and the occurrence of rust on the metal cords was observed. The smaller the numerical value, the better the less rust is generated.

<Strength Retention after Running Tire> After running the tire for about 200,000 km, the tire is disassembled and a metal cord is taken out. The higher the value, the better. Table 1 shows the test results.

[0049]

[Table 1]

Each of Comparative Examples 1 to 11 and Examples 1 to 7 is a cord composed of nine metal filaments having a wire diameter d of 0.38 mm. 18 except for Examples 6 and 7 and Examples 2 and 3
It was unified to 0 mm (10 times the final twist pitch Pc), and the twist direction and the final twist direction when forming the filament bundle were the same.

Comparative Example 1 is a compact cord (corresponding cord), Comparative Example 2 is an unmolded filament, Comparative Example 3 is a three-dimensional spiral shaped filament, and Comparative Example 4 is a molded filament Is a kind, and twisted without forming a filament bundle, Comparative Example 5 has d × h / Pw of more than 0.028, and Comparative Examples 6 and 7 have final twist pitches outside the specified range. In Comparative Examples 8 and 9, d × h / Pw was out of the specified range, and in Comparative Examples 10 and 11, the wave height was out of the specified range.

On the other hand, in Examples 1 to 7, the cord diameter was in the range of, for example, 1.41 to 1.45 mm, and Comparative Example 2 was used.
(Spiral wave) was confirmed to be more compact. Further, the strength of the cord, the rate of decrease in strength, the elongation under load (at 50 N), the bending stiffness of the cord, and the like are shown in Comparative Example 1.
It can be confirmed that excellent code characteristics are exhibited without inferiority to the compact code.

Further, the cord of the embodiment has a rubber diameter of 90% or more, while keeping the cord diameter compact, and the rust generation rate on the tire is very low and very good.

As in Comparative Examples 2 and 4, if all the filaments are not molded, or if only one type is formed, the permeability of the rubber decreases. Further, as in Comparative Examples 5, 8, and 9, when d × h / Pw is out of the specified range, the strength reduction rate and the rubber permeability cannot be compatible.

Further, as in Comparative Example 6 or 7, when the final twist pitch is out of the specified range, the elongation under load becomes too large or too small, thereby impairing the shape retention of the tire, for example. is there.

Further, as in Comparative Example 10 or 11, when the relationship between the filament diameter and the wave height h is out of the range of the present invention, a problem is caused in the rubber permeability or strength reduction rate.

Example 8 used nine metal filaments having a wire diameter of 0.30 mm, Example 9 used nine metal filaments having a wire diameter of 0.45 mm, and Example 10 used nine metal filaments. In Example 11, the filament diameter was 0.38 mm and eight filaments were used, and the filament bundle was composed of two filament bundles and three filament bundles. In Example 11, the metal filament diameter was 0.30 mm and ten filaments were used. is there. Each of the examples has a good rubber penetration rate and a good strength retention rate while achieving a compact cord diameter.

In the above embodiments, filaments having the same diameter are used, but a plurality of types of filaments having different wire diameters d may be mixed.

[0059]

As described above, the metal cord according to claim 1 or 2 can increase the degree of rubber penetration into the cord while reducing the cord diameter, and greatly reduces the generation of rust inside the cord. To improve durability. In addition, the strength of the cord, strength reduction rate, elongation under load (at 50 N),
As for the bending stiffness of the cord, it can exhibit good characteristics comparable to that of the compact cord. Further, it is preferable that the filament bundle is twisted while being twisted, since the cord diameter can be made more compact and the permeability of rubber into the cord can be further increased.

According to the third aspect of the present invention, the plurality of filament bundles include at least two or more three filament bundles composed of three molding filaments, so that more gaps are provided between the filaments. It can be formed to increase the permeability of rubber and further improve the cord durability.

According to the fourth aspect of the present invention, by using the metal cord for the belt layer of the tire, the generation of rust inside the tire of the metal cord can be suppressed, and the decrease in the strength of the cord and the breakage can be effectively prevented. Prevent and tire durability,
Shape retention and the like can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B are plan views showing an example of a molding filament. FIG.

FIG. 2 is a side view illustrating a method for manufacturing a metal cord.

FIG. 3 is a perspective view illustrating a filament bundle.

FIGS. 4A and 4B are cross-sectional views illustrating a filament bundle in the case of eight filaments.

FIGS. 5A and 5B are cross-sectional views illustrating a filament bundle having nine filaments.

FIGS. 6A and 6B are cross-sectional views illustrating a filament bundle in the case of ten filaments.

7A is a cross-sectional view illustrating an example of a metal cord including nine filaments, and FIG. 7B is a cross-sectional view illustrating an example of a metal cord including eight filaments.

FIG. 8 shows the rate of decrease in cord strength, rubber permeability, and d × h /
It is a graph which shows the relationship of Pw.

FIG. 9 is a plan view illustrating the overlapping of waves of the forming filament.

FIG. 10 is a sectional view of a compact cord.

FIG. 11 is a sectional view of an open cord.

FIG. 12 is a cross-sectional view of a cord including a spiral shaped filament.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal cord 2 Metal filament 2A Molding filament 3 Linear part 4, 4A, 4B Filament bundle

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Sakai 650 No. 63 Roy Jarlezan 309, Kamioso-cho, Utsunomiya-shi, Tochigi (56) References JP-A-10-110396 (JP, A) 33277 (JP, A) JP-A-5-279974 (JP, A) JP-A-1-162885 (JP, A) JP-A 9-13289 (JP, A) JP-A-48-17462 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) D07B 1/06 B60C 9/00 EUROPAT (QUESTEL) WPI / L (QUESTEL)

Claims (1)

(57) [Claims] 1. N-pieces having a wire diameter d of 0.30 to 0.45 mm
(N = 8, 9, 10) , and all the metal filaments have a two-dimensional wavy shape having a straight portion between a wave crest and a valley before being twisted. And at least said wave pitch P
While two or more types of shaping filaments having different w are included, the shaping wave pitch Pw and the wave height h are the same for each of the different types of filaments, and the wire diameter d, the shaping wave pitch Pw, and the wave height of the shaping filament. The value h satisfies the relationship of the following formulas: 5.0d ≦ Pw ≦ 30.0d 0.2d ≦ h ≦ 3.0d 0.014 ≦ d × h / Pw ≦ 0.028 Pw: Molding The wave pitch of the filament (mm) h: The wave height of the forming filament (mm) d: The wire diameter of the forming filament (mm) Two to three of the above-mentioned forming filaments including two or more types are bundled and the final twist pitch Pc is determined. A plurality of filament bundles are formed by being twisted at a pitch Pf of 3 to 20 times, and this filament bundle is twisted in the following combinations i ) to vi ):
A metal cord which is combined and has a twist pitch Pc of 10 to 40 mm. i) when n = 8, consisting of two different shaped filaments
Two filament bundles 4 ii) the same typed filaments of two and one different pins
3-filament bundle consisting of staple shaped filaments
Two and two different shaped filaments
When one bundle of two filaments consists of n = 9 iii) It consists of two different shaped filaments
Three bundles of two filaments and two identical molds
Lament and one different pitch molding filament
One iv) and the same typing filaments of the two three filament bundles composed of, different one
Three filaments consisting of pitch forming filaments
3 in a bundle, n = 10 v) Consists of two differently shaped filaments
Vi) two filament bundles vi) two identical shaped filaments and one different
3-filament bundle consisting of staple shaped filaments
Two and two different shaped filaments
Two filament bundles