KR20120133926A - Steel cord having improved degree of penetration of rubber - Google Patents

Abstract

PURPOSE: A steel cord with improved rubber penetration is provided to minimize air gap between filaments and to prevent penetration of salts or moisture and tire durability reduction. CONSTITUTION: A steel cord with improved rubber penetration sequentially comprises an inner layer(10), a middle layer(20), an outer layer(30), and a spiral wrap(40) from the center to the outside. The inner layer comprises three filaments(11) and is twisted in a clockwise or counterclockwise direction. The middle layer comprises 8 filaments(21) and is twisted in same direction with the inner layer.

Description

Steel cord having improved degree of penetration of rubber}

The present invention relates to a steel cord with improved rubber permeability, and in particular, to improve rubber permeability of the multi-layered steel cord to minimize voids between the filaments, thereby preventing salt or water from penetrating between the pores, thereby flattening. It relates to a steel cord with improved rubber permeability to prevent tire deterioration due to casting wear and corrosion.

The steel cord is alloy wired with 0.1 to 0.4 mm wire, 0.1 to 0.4 μm thick copper, zinc, nickel, cobalt and tin, and alloyed with 1 to 4 elements made of carbon steel. Therefore, it is made by twisting with various structures (1 × 4, 1 × 3, 2 + 2, 2 + 7, 3 + 6, 3 + 9 + 15, etc.) and has different kinds of strength, modulus, heat resistance and fatigue resistance. It is used as rubber reinforcement materials such as tires because it is superior to inorganic fibers and organic fibers.

In general, steel cords should be excellent in adhesion with rubber, which is a heterogeneous material because they are used as reinforcing materials for tires, and should be excellent in the harsh environment formed during driving of a vehicle. In the steel cord and tire manufacturing industry, much research has been conducted to improve such durability.

Currently, steel cords of 3 + 9 + 15 + 1 construction are commonly used as radial tire reinforcements for trucks and buses. In this standard, 3 wires, 9 wires and 15 wires are closely adhered to each other, so that the rubber permeability is poor, voids are formed between the filaments, salt or water penetrates between the formed voids, and the friction between the wires causes the so-called flatting wear and corrosion. Due to the problem of falling tire durability.

The present invention has been invented to solve the above problems, the present invention improves the rubber permeability of the multi-layered steel cord to minimize the voids between the filaments, thereby preventing the phenomenon of salt or water penetrating between the pores flat It is an object of the present invention to provide a steel cord with improved rubber permeability, which prevents deterioration of tire durability due to casting wear and corrosion.

The steel cord having improved rubber permeability according to the present invention is a steel cord having a structure in which an innermost layer, an intermediate layer, an outermost layer, and a spiral wrap are sequentially stacked from the center to the outer direction, and the innermost layer is composed of three filaments and is clockwise or It is twisted counterclockwise and has a twist length of 4 to 12 mm. The middle layer is composed of eight filaments, twisted in the same direction as the innermost layer, and has a twist length of 1.5 to 2.5 times the twist length of the innermost layer. Wherein the outermost layer consists of 13 filaments and is twisted in the opposite direction to the innermost layer and the intermediate layer and has a twist length of 12 to 28 mm, and the spiral wrap consists of one filament and is opposite to the outermost layer Twisted and characterized in that the twist length is 3 ~ 7 mm.

According to another preferred feature of the invention, the twist lengths of the innermost layer, the intermediate layer, the outermost layer and the spiral wrap are different from each other.

According to another preferred feature of the present invention, the individual filaments constituting the intermediate layer and the outermost layer are kept at a distance from the adjacent filament at a predetermined distance.

According to another preferred feature of the present invention, the wire diameters of the filaments constituting the innermost layer, the intermediate layer, the outermost layer, and the spiral wrap satisfy the following equation.

0.08 mm <D1, D2, D3 <0.30 mm Formula (1)

D1-0.05 mm <D2 <D1 + 0.05 mm ---- Equation (2)

D2-0.05 mm <D3 <D2 + 0.05 mm ---- Equation (3)

0.10 mm <D4 <0.25 mm (4)

[Wherein, D1, D2, D3 and D4 are the diameters of the filaments constituting the innermost layer, the middle layer, the outermost layer and the spiral wrap, respectively]

According to another preferred feature of the present invention, the steel cord is a fresh filament after the surface plating to improve the rubber adhesion to the wire rod having a carbon content of 0.70% to 1.3%.

Steel cords according to the present invention reduce the number of filaments in the middle layer and the outermost layer compared to the conventional steel cord, and by forming a space in which rubber can penetrate between the filaments and between layers by varying the twist length of the innermost layer and the middle layer. This facilitates the penetration of rubber between the innermost layer and the intermediate layer, thereby preventing corrosion between wires and corrosion by salt or water, and increasing the bond between the wire and rubber from the innermost layer to the outermost layer, resulting in breakage of the steel cord. The strength is increased to improve the durability of the tire. In addition, since the amount of steel cord used to achieve the equivalent breaking strength is reduced, tire manufacturing cost can be reduced, and tire weight can be reduced, thereby improving automobile fuel economy.

1 is a schematic diagram of a steel cord with improved rubber permeability according to the present invention,
FIG. 2 is a cross-sectional view of the AA ′ portion of FIG. 1. FIG.

1 is a schematic view of a steel cord with improved rubber penetration degree according to the present invention, Figure 2 is a cross-sectional view of the AA 'portion in FIG. As shown in Figures 1 and 2, the steel cord with improved rubber permeability according to the present invention is the innermost layer 10, the middle layer 20, the outermost layer 30 and the spiral wrap 40 from the center to the outer direction It has a stacked structure sequentially.

Hereinafter, each layer will be described.

The innermost layer 10 is a layer located at the center of the steel cord, and the three filaments 11 are twisted together. Here, the direction in which the three filaments 11 are twisted is clockwise or counterclockwise.

The intermediate layer 20 is a layer located outside the innermost layer 10, which has a structure in which eight filaments 21 are bonded in a donut shape. The filament of the conventional steel cord is usually installed 9, in the present invention, by reducing it one by one so that a little space can be formed between the individual filaments constituting the intermediate layer (20). In addition, the twist direction of the intermediate layer 20 is the same as the innermost layer 10, but the twist length is 1.5 to 2.5 times the twist length of the innermost layer 10. If the twist length is less than 1.5 times or more than 2.5 times, migration of the innermost layer 10 inside the tire may be a problem.

The outermost layer 30 is a layer located outside the intermediate layer 20, which is composed of 13 filaments 31. Here too, two filaments are reduced in comparison with the conventional outermost layer 30 so as to form a little space between the individual filaments constituting the outermost layer 30. Since rubber is very easy to penetrate into the space formed between the filaments of the outermost layer 30 and the intermediate layer 20, it contributes to the improvement of durability. Meanwhile, the twisting direction of the outermost layer 30 may be formed in a direction opposite to the rotation direction of the innermost layer 10 or the intermediate layer 20, and the twisting length of the outermost layer 30 may be 12 to 28 mm. desirable.

Spiral wrap 40 is composed of a line of filaments surrounding the outermost layer 30, which is twisted in the opposite direction to the outermost layer 30, the twist length is 3 ~ 7 mm.

On the other hand, in the present invention, the rubber between the filaments constituting the individual layers to improve the penetration of the rubber in the individual layers constituting the innermost layer 10, the intermediate layer 20, the outermost layer 30 and the spiral wrap 40 It is desirable to make the twist lengths of the individual layers different in order to form a space through which they can penetrate.

In particular, the filaments constituting the steel cord have different twist lengths of the innermost layer 10 and the intermediate layer 20 so as to maintain a spaced distance from each other, and the individual components constituting the intermediate layer 20 / outer layer 30. It is preferable to form the number of filaments in a smaller number than the conventional one.

Moreover, it is preferable that the wire diameter of the filament which comprises the innermost layer 10, the intermediate | middle layer 20, the outermost layer 30, and the spiral wrap 40 satisfy | fills following formula. This wire diameter is to make the filament twist well.

0.08 mm <D1, D2, D3 <0.30 mm Formula (1)

D1-0.05 mm <D2 <D1 + 0.05 mm ---- Equation (2)

D2-0.05 mm <D3 <D2 + 0.05 mm ---- Equation (3)

0.10 mm <D4 <0.25 mm (4)

[Wherein, D1, D2, D3, D4 are the diameters of the filaments constituting the innermost layer 10, the intermediate layer 20, the outermost layer 30 and the spiral wrap 40, respectively]

On the other hand, the steel cord in the present invention is a steel cord to which fresh filament is applied after the surface plating to improve the rubber adhesion to the wire rod having a carbon content of 0.70% to 1.3%. If the carbon content of the wire rod is less than 0.07%, the breaking strength may be exceeded, and if the carbon content exceeds 1.3%, problems may occur in wet drawing processability.

In addition, the surface plating is preferably made of brass excellent in adhesion to the rubber and adhesive strength due to aging (aging).

Based on the following Examples and Comparative Examples will be described in detail the configuration and operation of the embodiment of the present invention. However, the following examples are provided to enable those skilled in the art to fully understand the present invention, but the scope of the present invention is not limited by the embodiments described below.

Example 1

The wire rods having a carbon content of 0.82% and a diameter of 5.5 mm were first drawn to have a diameter of 1.10 mm, followed by a plating process and brass plating, and a final drawing was performed to a diameter of 0.18 mm to prepare a filament. Then twist 3 wires to 5 mm, 8 wires to 10 mm in the same direction as 3 wires, 13 wires to 8 wires and 16 mm in two directions, and the outermost one wire to 5 mm 13 wires in two directions (40) Twist in the form. The results of the evaluation of the main physical properties of the steel cord made at this time are shown in the following [Table 1].

Comparative Example 1

The wire rods having a carbon content of 0.72% and a diameter of 5.5 mm were first drawn to have a diameter of 1.10 mm, followed by a plating process and brass plating, and a final drawing was carried out to 0.175 mm in diameter to prepare a filament. Then twist 3 wires to 5 mm, 9 wires to 10 mm in the same direction as 3 wires, 15 wires to 8 wires and 16 mm in two directions, and 1 outermost wire 5 mm to 13 wires in two directions (40) Twist in the form. The results of the evaluation of the main physical properties of the steel cord made at this time are shown in the following [Table 1].

Sample classification Example
(3 + 8 + 13 + 1) Comparative Example
(3 + 9 + 15 + 1) Test standard Carbon content (%) 82 70 Wire Rod Maker Mill Sheet Filament Diameter (mm)
(D1 / D2 / D3 / D4) 0.18 / 0.18 / 0.18 / 0.15 0.175 / 0.175 / 0.175 / 0.15 ASTM-D-4975-93 Pitch (mm) 5/10/16/5 5/10/16/5 ASTM-D-2969 Twisting direction S / S / Z / S S / S / Z / S ASTM-D-2969 Cord diameter (mm) 1.33 1.34 ASTM-D-2969 Breaking Force (Kgf) 180 165 ASTM-D-2969 Unit weight (g / m) 5.1 5.4 ASTM-D-2969 Elasticity (%) 75 75 Self standard Adhesive force (kgf / 1inch) 140 135 ASTM-D-2229

Note 1) "S": clockwise, "Z": counterclockwise

Note 2) According to the "self standard", prepare the sample so that the sample is circled around the zero point of the elastic modulus measuring plate so that it matches the circular shape of the measuring plate, and slowly pull it downward from the top of the circular shape. Pull to reach the 0% point (pull rate: 20% / sec), press and hold for 10 seconds at the 0% point, then move upwards by 20% in 1 second again to display the data at the point where the sample stops. Read the value and measure the modulus of elasticity.

As described above, the steel cord of the present invention has an increased rubber penetration rate compared to the existing one, thus increasing the breaking strength (109% compared to Comparative Example 1), thereby improving tire durability, and increasing the breaking strength with an equivalent cord diameter. As it can reduce costs, it will contribute to cost reduction. In addition, since the unit weight is reduced (94.4% compared to Comparative Example 1), it is expected to contribute to the improvement of the fuel efficiency of the car by reducing the tire weight.

10: innermost layer
20: middle layer
30: outermost layer
40: Spiral Lab

Claims (5)

In the steel cord having a structure in which the innermost layer, the middle layer, the outermost layer, and the spiral wrap are sequentially stacked from the center to the outer direction,
The innermost layer consists of three filaments, twisted clockwise or counterclockwise, with a twist length of 4-12 mm,
The intermediate layer is composed of eight filaments, twisted in the same direction as the innermost layer, having a twist length of 1.5 to 2.5 times the twist length of the innermost layer,
The outermost layer is composed of 13 filaments, twisted in the opposite direction to the innermost layer and the intermediate layer, the twist length is 12 ~ 28mm,
The spiral wrap is composed of one filament, twisted in the opposite direction to the outermost layer, the steel cord with improved rubber penetration, characterized in that the twist length is 3 ~ 7 mm. The steel cord with improved rubber penetration according to claim 1, wherein the twist lengths of the innermost layer, the intermediate layer, the outermost layer, and the spiral wrap are different from each other. The steel cord with improved rubber penetration according to claim 1, wherein the individual filaments constituting the intermediate layer and the outermost layer are kept at a predetermined distance from the adjacent filaments. The steel cord of claim 1, wherein the wire diameters of the filaments constituting the innermost layer, the intermediate layer, the outermost layer, and the spiral wrap satisfy the following formula.
0.08 mm <D1, D2, D3 <0.30 mm ---- Equation (1)
D1-0.05 mm <D2 <D1 + 0.05 mm ---- Equation (2)
D2-0.05 mm <D3 <D2 + 0.05 mm ---- Equation (3)
0.10 mm <D4 <0.25 mm ---- Equation (4)
[Wherein, D1, D2, D3, D4 are the diameters of the filaments constituting the innermost layer 10, the intermediate layer 20, the outermost layer 30 and the spiral wrap 40, respectively] The steel cord of claim 1, wherein the steel cord is a steel cord to which fresh filaments are applied after surface plating to improve rubber adhesion to a wire rod having a carbon content of 0.70% to 1.3%. code.

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