KR102274567B1 - Steel cord for tire reinforcement having excellent rubber penetration - Google Patents

Abstract

The present invention relates to a steel cord for tire reinforcement having excellent rubber permeability, which comprises: a core; an intermediate strand disposed on the outer periphery of the core and formed by a plurality of intermediate filaments twisting while forming first pitch (p_1); and an upper strand disposed on the outer periphery of the intermediate strand, and formed by a plurality of upper strands twisting while forming second pitch (p_2), wherein the first pitch (p_1) and the second pitch (p_2) show a different interval from each other.

Description

Steel cord for tire reinforcement having excellent rubber penetration

The present invention relates to a steel cord for reinforcing a tire having excellent rubber permeability, and more particularly, by twisting two strands surrounding a core at the same continuous direction and at different pitches to secure a gap between filaments to improve rubber permeability It relates to a steel cord for tire reinforcement with excellent rubber permeability.

Steel cord for tire reinforcement has excellent characteristics such as strength, modulus, heat resistance, fatigue resistance and rubber adhesion among various types of reinforcement materials used for reinforcement of various rubber products including vehicle tires and industrial belts. have According to these characteristics, a steel cord is widely used as a tire reinforcing material as a member suitable for satisfying the functionality required for a tire, and its usage tends to increase day by day.

Steel cords require high strength to reinforce high-load tires, and as a result, steel cords are being manufactured using multiple filaments. The steel cord produced through multi-filaments is coated with rubber to make a tire.

However, the conventional steel cord for tire reinforcement has the following problems. When driving while using a high-load tire, a strong force is applied to the filaments, and friction occurs between the filaments by this force.

If the rubber permeability between the filaments is good, it is possible to absorb the load due to friction, but if the rubber permeability between the filaments is not good, the load due to friction is generated. When the load due to friction continues for a long time, there is a problem in that the fatigue value rapidly decreases as the load due to friction acts as a repetitive load.

In addition, abrasion may occur in the filament due to friction of the filament, and moisture may penetrate into the rubber layer through the abrasion. When moisture enters the rubber layer, corrosion occurs in the steel cord, and there is a problem in that the strength of the steel cord is lowered by corrosion.

In order to prevent such a phenomenon, it is necessary to improve the rubber permeability between the filaments, but there is a problem in that it is difficult to effectively improve the rubber permeability through the conventional steel cord.

The present invention is to solve the above problems, and more specifically, by twisting two strands surrounding the core in the same continuous direction and at different pitches to secure the spacing between the filaments, the rubber permeability is improved. It relates to an excellent steel cord for tire reinforcement.

The steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above-described problems includes: a core; It is disposed on the outer periphery of the core, a plurality of intermediate strands formed by twisting while forming _{a first pitch (p 1 );} It is disposed on the outer periphery of the intermediate strand, and a plurality of upper strands are _{twisted while forming a second pitch (p 2} ) and an upper strand formed by twisting; including, the first pitch (p ₁ ) and the second pitch (p _{2 )} ) is characterized in that the spacing is different from each other.

The core of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above-mentioned problems is made of one core filament, the middle twisted strand is made of 6 double twisted filaments, and the upper twisted strand is 9 to It may consist of 11 leading filaments.

The value of the length of _{the first pitch (p 1} ) with respect to the length of _{the second pitch (p 2} ) of the steel cord for tire reinforcement having excellent rubber permeability of the present invention for solving the above problems may be 0.4 to 0.6 have.

In the steel cord for tire reinforcement having excellent rubber permeability of the present invention for solving the above-mentioned problems, the diameter (d ₁ ) of the intermediate filament and the diameter (d ₂ ) of the upper filament of the steel cord for reinforcing the rubber of the present invention may be the same.

_{The diameter (d 0} ) of the core to the sum of the diameter (d ₀ ) of the core and the diameter (d ₁ ) of the intermediate filaments of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above problems (d 0 ) The value of may be 0.51 to 0.56.

_{The diameter (d 1} ) of the intermediate filament and the upper filament (d ₂ ) of the steel cord for tire reinforcement having excellent rubber permeability of the present invention for solving the above problems may be made of 0.15 to 0.35 mm.

Before the plurality of double-twisted filaments are twisted in the double-twisted strand of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above-mentioned problems, a mold portion may be formed on the double-twisted filaments along the longitudinal direction of the double-twisted filaments. have.

The shape of the intermediate filament of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above problems is an upper gear having a plurality of first teeth on the outside and a plurality of second teeth on the outside. The intermediate filament may be formed while passing between the lower gears.

In the intermediate strand formed by twisting a plurality of the intermediate filaments of the steel cord for reinforcing a tire having excellent rubber permeability of the present invention for solving the above-mentioned problems, the mold portion may be formed on at least two or more of the intermediate filaments.

The mold portion of the intermediate filament of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above problems is extended while having a cycle, and the height difference between the highest point and the lowest point in the mold part is called the digging height (h), , when the length of one cycle of the mold portion is referred to as a parger (L), the value of the wave height (h) with respect to the parger (L) may be 0.7 to 1.0.

The mold portion of the intermediate filament of the steel cord for tire reinforcement with excellent rubber permeability of the present invention for solving the above problems is extended while having a cycle, and the height difference between the highest point and the lowest point in the mold part is called the digging height (h), , When the length of one cycle of the mold part is referred to as a parger (L), the value of the wave height (h) for the product of the diameter of the parger (L) and the upper filament may be 2.0 to 2.9.

The present invention relates to a steel cord for reinforcing a tire having excellent rubber permeability, and by twisting two strands surrounding a core at the same continuous direction and at different pitches to secure a gap between filaments, the advantage of improving rubber permeability There is this.

In addition, the present invention has an advantage in that the permeability of rubber can be improved by forming a cross-stranded strand by giving a shape to the middle-twisted filament while controlling the diameter ratio of the core and the middle-twisted filament.

In addition, the present invention has the advantage of being able to reduce the abrasion between the filaments by improving the rubber permeability, thereby preventing the penetration of moisture to prevent corrosion of the steel cord. In addition, the present invention has an advantage in that the fatigue life due to long-term use of the tire can be improved by improving the rubber permeability.

1 is a cross-sectional view of a steel cord for reinforcing a tire having excellent rubber permeability according to an embodiment of the present invention.
Figure 2 (a) shows that the filament is twisted, Figure 2 (b) is a middle strand is formed by twisting the middle filament around the core according to the embodiment of the present invention, the upper filament is twisted around the middle strand It is a view showing that the upper strand is formed.
Figure 3 is a view showing that the mold portion is given to the intermediate filament through the upper gear and the lower gear according to an embodiment of the present invention.
Figure 4 is a view showing the wave height (h) and the pagger (L) of the mold formed in the middle filament filament according to an embodiment of the present invention.
5 is a table showing conditions of Examples and Comparative Examples of the present invention.
6 is a view showing the results of air permeability evaluation for Examples and Comparative Examples of the present invention.
7 is a view showing the results of 3-Roll fatigue evaluation for Examples and Comparative Examples of the present invention.
8 is a view showing the results of shoe shine fatigue values for Examples and Comparative Examples of the present invention.

This specification clarifies the scope of the present invention, explains the principles of the present invention, and discloses embodiments so that those of ordinary skill in the art to which the present invention pertains can practice the present invention. The disclosed embodiments may be implemented in various forms.

Expressions such as “comprises” or “may include” that may be used in various embodiments of the present invention indicate the existence of a corresponding disclosed function, operation, or component, and may include one or more additional functions, operations, or components, etc. are not limited. In addition, in various embodiments of the present invention, terms such as "comprise" or "have" are intended to designate that a feature, number, step, action, component, part, or combination thereof described in the specification is present, It should be understood that it does not preclude the possibility of addition or existence of one or more other features or numbers, steps, operations, components, parts, or combinations thereof.

When a component is referred to as being “connected to and coupled to” another component, the component may be directly connected or coupled to the other component, but between the component and the other component. It should be understood that there may be other new components in the . On the other hand, when an element is referred to as being "directly connected" or "directly coupled" to another element, it will be understood that no new element exists between the element and the other element. should be able to

The terms first, second, etc. used herein may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The present invention relates to a steel cord for reinforcing a tire having excellent rubber permeability, and by twisting two strands surrounding a core at the same continuous direction and at different pitches to secure a gap between filaments, the rubber permeability has improved rubber permeability. It relates to an excellent steel cord for tire reinforcement.

The steel cord for tire reinforcement with excellent rubber permeability according to an embodiment of the present invention can be used as a steel cord suitable for reinforcing a medium-to-large truck and a steel cord for a radial tire for a passenger car. However, the present invention is not limited thereto, and the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention may be used for various tires.

In the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention, the filaments (core filament, middle-stretched filament, and upper-stretched filament) to be described later may be manufactured as a wire rod, and may be a single wire. The filament according to an embodiment of the present invention may be manufactured through a pickling process, a wire drawing process, a heat treatment process, and a plating process.

Specifically, the filament may be rinsed with water and dried after being pickled by a mechanical descaling and chemical pickling method using a pickling solution to remove oxides present on the surface.

Thereafter, the filament may be dry drawn to a diameter of 1.0 to 2.5 mm through a first drawing process, and intermediate heat treatment may be performed to improve workability of drawing and stranding. Heat treatment may be performed from austenite to pearlite transformation temperature between about 580 ~ 620 ℃ after heating to a temperature of about 1000 ℃.

After the intermediate heat treatment, brass plating may be performed to improve adhesion between the filament and the rubber. Here, instead of brass plating, ternary alloy plating including a third alloy such as cobalt and nickel in addition to copper and zinc plating may be performed. The filament plated with brass plating or a ternary alloy may be finally reduced in cross section by wet drawing and drawn to a target diameter, thus completing the production of the filament before the stranding operation.

However, the filament according to the embodiment of the present invention is not limited to being manufactured by the above process, and the filament used for the steel cord may be manufactured through various processes. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 , the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention includes a core 110 , a middle strand 120 , and an upper strand 130 .

The core 110 is disposed at the center of the steel cord, and the core 110 includes a core filament 111 . One core filament 111 may be disposed. However, the present invention is not limited thereto, and the number of the core filaments 111 may be changed as needed.

The double-stranded strand 120 is disposed on the outer periphery of the core 110 , and a plurality of double-stranded filaments 121 are twisted to form _{a first pitch (p 1 ).} As shown in Fig. 2(a), a plurality of the double-stranded filaments 121 may be twisted, and the double-stranded strand 120 is a plurality of the double-stranded filaments 121 around the core 110 as shown in FIG. 2(b). may be formed by twisting.

Referring to FIG. 2( b ), the plurality of double- _{stranded filaments 121 may be twisted while forming the first pitch p 1} , and the double-stranded strand 120 is six of the double-stranded filaments 121 . It can be made by twisting. However, the present invention is not limited thereto, and the number of the intermediate filaments 121 may be changed as needed.

The upper strand 130 is to be disposed on the outer periphery of the intermediate strand 120, a plurality of upper filament 131 is formed by twisting while forming _{a second pitch (p 2 ).} As shown in FIG. 2( a ), a plurality of the upper-stretched filaments 131 may be twisted, and the upper-stranded strand 130 is a plurality of the upper-stretched filaments 131 around the intermediate strand 120 as shown in FIG. 2( b ). ) can be twisted.

Referring to Figure 2 (b), the plurality of the upper filament 131 is _{to be twisted while forming the second pitch (p 2} ), the upper strand 130 is 9 to 11 of the upper filament ( 131) can be produced by twisting.

If the number of the upper filaments 131 is too large (more than 11), there is a problem in that the permeability of the rubber is weakened as the voids between the filaments become smaller. In addition, if the number of the upper strands 131 is too small (less than 9), there is a risk that the strength of the steel cord is lowered as the shape of the upper strand becomes unstable due to the occurrence of too many voids.

Therefore, the number of the upper filament 131 is preferably 9 to 11. However, the number of the stranding filaments 131 is not limited thereto, and the number of the stranding filaments 131 may be changed as needed.

The intermediate strand 120 and the upper strand 130 may be twisted while extending in the same continuous direction, having different pitches. That is, the first pitch (p ₁ ) formed in the intermediate filament 121 and the second pitch (p ₂ ) formed in the upper filament 131 may be formed at different intervals.

In this way, the gap between the filaments is widened by differentiating the spacing between the first pitch (p _{1 ) formed in the double-stranded filament 121 and the second pitch (p 2} ) formed in the upper-stretched filament 131 . and, through this, it is possible to improve the permeability of the rubber.

According to an embodiment of the present invention, the value of the length of the first pitch p _{1 to the length of the second pitch p 2} may be 0.4 to 0.6. (0.4 ≤ p ₁ /p ₂ ≤ 0.6) Since the upper strand 130 is disposed on the outside of the intermediate strand 120, the second pitch (p ₂ ) formed in the upper strand 130 is the length of _{When the length of the first pitch (p 1} ) formed in the intermediate strand 120 is longer than the length, it is possible to effectively form a void between the upper strand 130 and the intermediate strand 120 .

_{At this time, if the value of the length of the first pitch (p 1} ) with respect to the length of the second pitch (p ₂ ) is too small (less than 0.4), the upper strand 130 as too many voids are formed. There is a problem in that the upper strand 130 is not supported by the intermediate strand 120 as the shape of the upper strand becomes unstable.

_{Conversely, if the value of the length of the first pitch (p 1} ) with respect to the length of the second pitch (p ₂ ) is too large (greater than 0.6), between the upper strand 130 and the intermediate strand 120 As the pores become smaller, there is a problem in that the permeability of the rubber is weakened. Therefore, in order to support the upper strand 130 while improving the permeability of rubber, the value of the length of _{the first pitch p 1} with respect to the length of _{the second pitch p 2 is 0.4 to 0.6.} Do.

Referring to FIG. 1 , the diameter (d ₀ ) of the core with respect to the sum of the diameter (d ₀ ) of the core 110 and the diameter (d _{1 ) of the intermediate filament 121 according to an embodiment of the present invention (d 0 )} The value is preferably 0.51 to 0.56. (0.51 ≤ d ₀ /(d ₁ +d ₀ ) ≤ 0.56) Here, the diameter d ₀ of the core 110 may be the diameter of the core filament 111 .

When the diameter of the core 110 is formed too large, there is a problem in that the shape of the double-stretched filament 121 becomes unstable as too many voids are generated between the core 110 and the double-stranded filament 121. .

In order to solve this problem, the value of _{the diameter (d 0} ) of the core with respect to the sum of the diameter (d 0 ) of the core 110 and the diameter (d ₁ ) of the intermediate filament 121 according to an embodiment of the present invention (d _{0 ) is} It is preferably smaller than 0.56.

_{The diameter (d 0} ) of the core 110 with respect to the sum of the diameter (d _{0 ) of the core 110 and the diameter (d 1} ) of the double-stranded filament 121 must be less than 0.56 to improve the voids while improving the hollow filaments It becomes possible to prevent the shape of (121) from becoming unstable.

In contrast, when the diameter (d _0), the ratio of the core 110 is too small for the sum of the diameter (d ₁₎ of the diameter (d ₀₎ and the jungyeon filament 121 of the core 110, the core ( 110) and as it becomes difficult to form a void between the double-stranded filament 121, there is a problem in that the permeability of the rubber is reduced.

In addition, if the diameter (d ₀ ) of the core 110 is too small, the strength of the steel cord cannot be expressed. Since the core 110 is disposed at the center of the steel cord, when the diameter d ₀ becomes too small, the strength of the steel cord may not be expressed. A little more specific, the diameter (d _0), the ratio of the core 110 relative to the sum of the diameter (d ₁₎ of the diameter (d ₀₎ and the jungyeon filament 121 of the core 110 must be greater than 50% Strength can be expressed at the center of the steel cord.

_{Therefore, the value of the diameter (d 0} ) of the core with respect to the sum of the diameter (d 0 ) of the core 110 and the diameter (d ₁ ) of the intermediate filament 121 according to an embodiment of the present invention (d ₀ ) is less than 0.51 A large one is preferable.

Further, according to the embodiment of the invention, the diameter (d ₂₎ of the diameter (d ₁₎ and the upper edge filaments 131 of the filament jungyeon 121 is preferably the same. As described above, the _{value of the length of the first pitch p 1} with respect to the length of _{the second pitch p 2} may be 0.4 to 0.6.

In order to derive the ratio of the length of the first pitch (p ₁ ) to the length of the second pitch (p ₂ ) as described above, the upper filament 131 and the intermediate filament 121 are formed to have the same diameter. It is preferable to be

According to an embodiment of the invention, wherein for the length of the diameter, while the same (d _2), the second pitch (p ₂₎ of the diameter (d ₁₎ and the upper edge filament 131 of the jungyeon filament 121 When the value of the length of the first pitch p ₁ is 0.4 to 0.6, it is possible to improve the permeability of the rubber without affecting the strength of the steel cord.

According to an embodiment of the present invention, the diameter (d ₁ ) of the intermediate filaments and the diameter (d ₂ ) of the upper filaments may be 0.15 to 0.35 mm. However, the diameter (d ₁ ) of the intermediate filament and the diameter (d ₂ ) of the upper filament are not limited thereto, and may be changed as needed.

In the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention, before the plurality of the double-stranded filaments 121 are twisted in the double-stranded strand 120, the double-stranded filaments 121 have the double-stranded filaments (121). A shape portion may be formed along the longitudinal direction of the .

Referring to FIG. 3 , the mold portion of the intermediate filament 121 includes an upper gear 140 having a plurality of first tooth portions 141 on the outside, and a plurality of second tooth portions 151 on the outside. It is formed while the intermediate filament 121 passes through the lower gear 150 .

The mold portion 122 extends in a direction parallel to the direction in which the intermediate filament 121 extends while having a period as shown in FIG. 4 . The mold part 122 has a wave height h and a parger L, and the wave height h may be defined as the difference in height between the highest point and the lowest point in the mold part 122, and the parger L is the mold part (122) can be defined as the length of one period.

As described above, the double-stranded strand 120 may be formed by twisting a plurality of the double-stranded filaments 121, and before the plurality of the double-stranded filaments 121 are twisted to form the double-stranded strand 120, at least 2 The mold portion 122 may be formed in more than one of the intermediate filaments 121 .

In this way, before twisting the plurality of medium-twisted filaments 121 to form the medium-twisted strand 120 , the mold portion 122 is attached to the medium-twisted filament 121 through the upper gear 140 and the lower gear 150 . ) is formed, it is possible to increase the voids between the filaments 121 . As the voids between the double-stranded filaments 121 are increased, it is possible to improve the permeability of the rubber.

According to an embodiment of the present invention, in order to increase the void between the double-stranded filaments 121 by forming the mold portion 122 on the double-stranded filament 121, the height of the wave height (h) for the parger (L) is It is preferable that a value consists of 0.7-1.0. (0.7 ≤ h/L ≤ 1.0)

If the value of the wave height h for the parger L is too small (less than 0.7), the space in which the voids are formed between the intermediate filaments 121 becomes small, so it is difficult to effectively improve the permeability of the rubber. There is this.

Conversely, if the value of the digging height h for the parger L is too large (greater than 1.0), the upper gear 140 and the lower gear 150 must be tightened strongly, so that the middle filament 121 is disconnected. There is a problem that causes this.

More specifically, when the wave height (h) value is greater than the Parger (L) value, because the breakage may occur in the intermediate filament 121 due to the relatively large wave height (h) value, the Parger ( Preferably, the value of the wave height h with respect to L) is less than 1.0.

According to another embodiment of the present invention, the value of the wave height (h) for the product of _{the diameter (d 2 ) of the waver (L) and the upper filament 131 is preferably made of 2.0 to 2.9.} (2.0 ≤ (h/L)/d ₂ )≤ 2.9)

_{If the value of the wave height (h) for the product of the diameter (d 2} ) of the parger (L) and the upper filament 131 is too small (less than 2.0), the diameter (d) of the upper filament 131 ₂ ) Since the relative wave height (h) value becomes smaller, the space in which the void is formed between the intermediate filaments 121 becomes smaller.

When the space in which the void is formed between the double-stretched filaments 121 becomes small, it is difficult to effectively improve the permeability of rubber, so the product of _{the diameter (d 2 ) of the parger (L) and the upper-stretched filaments 131 is} It is preferable that the value of the wave height (h) is greater than 2.0.

More specifically, if the value of the wave height (h) for the parger (L) compared to the _{diameter (d 2 ) of the upper filament 131 is too small, the upper filament 131 inside the mold portion 122} It is difficult to effectively improve the permeability of rubber as the hollow filament 121 formed with the formed small voids (if the value of the wave height h for the parger L is too small, the voids are filled) There is a problem.

Conversely, if the value of the wave height h for the product of the parger L and the diameter d ₂ of the upper filament 131 is too large (greater than 2.9), the upper gear 140 and the lower gear There is a problem that disconnection occurs in the double-stranded filament 121 because the tightening of (150) must be strengthened.

More specifically, when the value of the wave height (h) for the parger (L) is large compared to the _{diameter (d 2 ) of the upper filament 131 , it corresponds to a case where the wave height (h) value is relatively large.} , When the wave height (h) is increased, a disconnection may occur in the intermediate filament 121 .

Therefore, the value of the wave height (h) for the product of _{the diameter (d 2} ) of the waver (L) and the upper filament 131 is preferably made of 2.0 to 2.9. More preferably, the value of the wave height h for the parger (L) is 0.7 to 1.0, and at the same time, the product of the parger (L) and the diameter (d ₂ ) of the upper filament 131 The value of the wave height (h) with respect to is preferably made of 2.0 to 2.9.

5 to 8 is a steel cord according to an embodiment of the present invention, air permeability evaluation, 3-roll fatigue evaluation, shoe shine fatigue evaluation for the comparative example is in progress.

Breathability evaluation is a test for evaluating the rubber penetration inside the steel cord. Specifically, a steel cord is placed between rubbers and vulcanized for a certain period of time while temperature and pressure are applied to push air into the cross-section of the specimen in which the rubber in the steel cord has penetrated. As an evaluation method to measure the time taken to raise, the longer the time, the better the rubber penetration.

For 3-roll fatigue evaluation, a fatigue evaluation specimen is prepared by putting one steel cord between rubbers and vulcanizing it, then the prepared specimen is mounted on a test equipment consisting of three rollers, and a load of 10% of the cord cutting force is applied. As three rollers move horizontally while applying bending stress to the cord, it is evaluated by the number of cycles until the cord breaks. A high number of cycles means an excellent fatigue value.

To evaluate the fatigue of the shoe shine, the test specimen was prepared by vulcanizing 10 steel cords with rubber, and then hung on a roller so that the prepared specimen was bent and both ends were fixed, and the fixed ends were repeatedly moved from side to side while in contact with the roller. While the part is subjected to repetitive bending stress, it is evaluated by the number of cycles until the cord breaks. A high number of cycles means an excellent fatigue value.

Referring to FIG. 5 , in the embodiments (Examples 1 to 3) of the present invention, the core filament 111 is wet-drawn to a final diameter of 0.22 mm using an intermediate heat treatment line, and the intermediate filaments are drawn using an intermediate heat treatment line. After wet-fresh 121 with a final diameter of 0.20 mm, six of the double-twisted filaments 121 are twisted to form the double-twisted strand 120 .

Here, when the six double-twisted filaments 121 are twisted to form the double-twisted strand 120 , the double-twisted strand 120 is formed using the double-twisted filament 121 to which the mold portion 122 is provided. .

After the intermediate strand 120 is formed, 11 of the stranded filaments 131 are twisted at a second pitch (p _{2 ) different from the first pitch (p 1 ) formed by the intermediate stranded filament 121 by twisting the stranded strand} By forming 130, a steel cord is manufactured. At this time, the diameter of the double-stranded filament 121 and the upper-stretched filament 131 was the same, and the double-stranded filament 121 and the upper-twisted filament 131 are twisted while extending in the same open direction.

Referring to FIG. 5 , in Comparative Example 1, the core 10a filaments were wet-drawn to a final diameter of 0.22 mm using an intermediate heat treatment line, and the intermediate filaments were wet-drawn with a final diameter of 0.20 mm using an intermediate heat treatment line. Twisting the double-twisted filaments form the double-twisted strand (20a). Here, when twisting six double-twisted filaments to form the double-twisted strand 20a, the double-twisted strand 20a is formed using the double-twisted filaments in which the mold is not formed.

After the middle stranded strand (20a) is formed, a steel cord is manufactured by twisting 12 upper stranding filaments at a pitch different from the pitch formed by the intermediate stranding filaments to form the upper stranding strand (30a). At this time, the diameters of the double-stranded filament and the upper-stretched filament were the same, and the middle-twisted filament and the upper-twisted filament were twisted while extending in the same direction.

Referring to FIG. 5 , in Comparative Example 2, the core 10b filaments were wet-drawn to a final diameter of 0.18 mm using an intermediate heat treatment line, and the intermediate filaments were wet-drawn with a final diameter of 0.22 mm using an intermediate heat treatment line. Twist the twisted filaments to form the twisted strand (20b). Here, when twisting five double-twisted filaments to form the double-twisted strand 20b, the double-twisted strand 20b is formed using the double-twisted filaments in which the mold portion is not formed.

After the middle stranded strand (20b) is formed, ten stranded filaments are twisted at the same pitch as the intermediate stranded filaments to form the upper stranded strand (30b) to manufacture a steel cord. At this time, the middle filament (0.22mm) and the diameter (0.24mm) of the upper filament are formed to be different from each other, and the middle filament and the upper filament are twisted while extending in the same direction.

6 is a result of the air permeability evaluation for Examples 1 to 3 and Comparative Example 1 and Comparative Example 2 of the present invention, Figure 7 is Examples 1 to 3 and Comparative Example 1 of the present invention , is a result of 3-roll fatigue evaluation for Comparative Example 2, and FIG. 8 is a shoe shine fatigue evaluation for Examples 1 to 3 and Comparative Example 1 and Comparative Example 2 of the present invention. It is the result.

First, comparing Comparative Example 1 and Comparative Example 2, it can be seen that Comparative Example 1 has better fatigue characteristics than Comparative Example 2 in air permeability evaluation, 3-roll fatigue evaluation, and shoe shine fatigue evaluation. In Comparative Example 1, unlike Comparative Example 2, the diameters of the middle-stretched filaments and the upper-stretched filaments are the same while the pitches of the middle-stretched filaments and the upper-stretched filaments are different.

As such, if the diameters of the middle-stretched filament and the upper-stretched filament are the same while the pitches of the double-stranded filament and the upper-stretched filament are different, the permeability of the rubber is improved as the voids increase, and thus, it can be seen that the fatigue property is improved.

Comparing Examples 1 to 3 and Comparative Example 1 and Comparative Example 2 according to an embodiment of the present invention, the implementation according to the embodiment of the present invention in air permeability evaluation, 3-roll fatigue evaluation, and shoe shine fatigue evaluation It can be seen that Examples 1 to 3 have better fatigue properties than Comparative Examples 1 and 2.

Examples 1 to 3 according to an embodiment of the present invention are the first pitch (p ₁ ) of the double-stranded filament 121 and the second pitch (p 2 ) of the upper-stretched filament 131 to be different, and the _{double-stranded filament (} Before 121 is twisted to form the middle-stranded strand 120, the mold portion 122 is given to the middle-twisted filament 121, and the diameter of the middle-twisted filament 121 and the upper-stranded filament 131 is the same.

As in Examples 1 to 3, the first pitch (p ₁ ) of the middle filament 121 and the second pitch (p ₂ ) of the upper filament 131 are different from each other, and the mold part 122 in the middle filament 121 ), it can be seen that the fatigue value characteristics are better than those of Comparative Example 1 and Comparative Example 2.

In Comparative Example 1, the number of stranded filaments was set to 12, whereas Examples 1 to 3 had the number of stranded filaments set to 11. Comparing Examples 1 to 3 and Comparative Example 1, when the number of stranded filaments is too large (if the number of stranded filaments is more than 12, Comparative Example 2), the fatigue property is not good, so the stranded filaments The number of is preferably less than 11.

In addition, in Comparative Example 2, the diameter value of the core with respect to the sum of the diameter of the core and the diameter of the double-stranded filament has a value less than 0.51. (Comparative Example 2, d ₀ /(d ₁ +d ₀ ) = 0.45) As in Comparative Example 2, when the diameter value of the core with respect to the sum of the diameter of the core and the diameter of the double-stranded filament is less than 0.51, the comparative example of FIG. 2 As shown in the figure, a small gap is formed. As shown in Comparative Example 2 of FIG. 5 , when the voids are small, the permeability of the rubber is not good, and the fatigue property is deteriorated.

Opposite of the core 110 as shown in Examples 1 to 3, the diameter (d ₀₎ to the value of the diameter (d ₀₎ of the core to the sum of the diameter (d ₁₎ of the jungyeon filament 121 When formed to 0.51 to 0.56, it is possible to stabilize the shape of the intermediate filament 121 with respect to the core 110 while improving the air gap, thereby improving the permeability of the rubber, thereby improving the fatigue property.

As described above, in Examples 1 to 3 according to the embodiment of the present invention, the permeability of the rubber was improved as the voids were enlarged under the above conditions, and it can be seen that the fatigue properties were improved through this.

The steel cord for tire reinforcement having excellent rubber permeability according to the embodiment of the present invention described above has the following effects.

The steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention is manufactured by twisting two strands surrounding the core in the same continuous direction and at different pitches, thereby securing a gap between filaments to improve the permeability of rubber. there are advantages to

In addition, the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention improves the permeability of rubber by providing a shape to the middle-stretched filament while controlling the diameter ratio of the core and the middle-stretched filament to form a cross-stranded strand. There are advantages that can be

At the same time, the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention can reduce wear between filaments by improving rubber permeability, thereby preventing penetration of moisture and causing corrosion in the steel cord. There are advantages to avoiding this.

In addition, the steel cord for tire reinforcement having excellent rubber permeability according to an embodiment of the present invention has the advantage of improving the rubber permeability and thus improving the fatigue life of the tire due to long-term use.

As described above, the present invention has been described with reference to one embodiment shown in the drawings, but it will be understood by those skilled in the art that various modifications and variations of the embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

110...Core 111...Core Filament
120...double twisted strand 121...double twisted filament
122...Brother-in-law 130...Standing Strand
131...upper filament 140...upper gear
141...First tooth 150...Lower gear
151...2nd tooth

Claims (11)

In the steel cord for tire reinforcement,
core;
It is disposed on the outer periphery of the core, a plurality of intermediate strands formed by twisting while forming _{a first pitch (p 1 );}
It is disposed on the outer periphery of the intermediate strand, a plurality of upper filaments are twisted while forming _{a second pitch (p 2 );}
The first pitch (p ₁ ) and the second pitch (p ₂ ) are spaced apart from each other,
Before the plurality of the double-twisted filaments are twisted in the double-twisted strand,
A shape portion is formed in the double-stranded filament along the longitudinal direction of the double-stranded filament,
The mold portion of the double-stranded filament is extended while having a cycle,
When the height difference between the highest point and the lowest point in the mold part is called the wave height (h), and the length of one cycle of the mold part is called the wave height (L),
The value of the wave height (h) for the waver (L) is 0.7 to 1.0,
A steel cord for tire reinforcement with excellent rubber penetration, characterized in that the value of the wave height (h) to the product of the diameter of the parger (L) and the upper filament is 2.0 to 2.9. According to claim 1,
The core consists of one core filament,
The double-stranded strand consists of six double-stranded filaments,
The upper strand is a steel cord for tire reinforcement with excellent rubber permeability, characterized in that it consists of 9 to 11 filaments. According to claim 1,
The value of the length of _{the first pitch (p 1} ) with respect to the length of the second pitch (p _{2 ) is 0.4 to 0.6.} 4. The method of claim 3,
A steel cord for tire reinforcement with excellent rubber permeability, characterized in that the diameter (d ₁ ) of the intermediate filament and the diameter (d _{2 ) of the upper filament are the same.} According to claim 1,
The value of the diameter (d ₀ ) of the core to the sum of the diameter (d ₀ ) of the core and the diameter (d ₁ ) of the double-stranded filament is 0.51 to 0.56. Steel cord for tire reinforcement with excellent rubber permeability, characterized in that . 6. The method of claim 5,
A steel cord for tire reinforcement with excellent rubber permeability, characterized in that the diameter (d ₁ ) of the intermediate filament and the diameter (d _{2 ) of the upper filament are 0.15 to 0.35 mm.} delete According to claim 1,
The shape of the double-stranded filament,
A steel cord for tire reinforcement with excellent rubber penetration, characterized in that the intermediate filament is formed while passing between an upper gear having a plurality of first teeth on the outside and a lower gear having a plurality of second teeth on the outside. According to claim 1,
In the double-twisted strand formed by twisting a plurality of the double-twisted filaments, the steel cord for tire reinforcement with excellent rubber permeability, characterized in that the mold portion is formed on at least two or more of the double-twisted filaments. delete delete

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