JP7367899B1 - Steel cord, cord-rubber composite, tire - Google Patents

Abstract

A single wire steel cord with a brass plating film on the surface, a cord diameter of 0.25 mm or more and 0.42 mm or less, an average value of the coil diameter measured at three locations of 500 mm or more and 600 mm or less, and one of the above three locations. Steel cord with a variation width of 50 mm or less in coil diameter measured at the site and a torsion of less than ±1 turn per 6 m.

Description

The present disclosure relates to steel cords, cord-rubber composites, and tires.

Patent Document 1 discloses a pneumatic tire in which a belt layer including a plurality of aligned single-wire steel wires is embedded in the outer peripheral side of a carcass layer in a tread portion, the single-wire steel wires having a flat cross-sectional shape and discloses a pneumatic tire characterized in that the thickness of the rubber under the groove in the tread portion is 1.0 mm to 2.0 mm.

Japanese Patent Application Publication No. 2018-058515

The steel cord of the present disclosure is a single wire steel cord,
Has a brass plating film on the surface,
The cord diameter is 0.25 mm or more and 0.42 mm or less,
The average value of the coil diameter measured at three locations is 500 mm or more and 600 mm or less, and the variation width of the coil diameter measured at the three locations is 50 mm or less,
Torsion per 6m is within ±1 turn.

FIG. 1 is a perspective view of a steel cord according to one aspect of the present disclosure. FIG. 2 is an explanatory diagram of the coil diameter of the steel cord according to one aspect of the present disclosure. FIG. 3 is an explanatory diagram of a method for manufacturing a steel cord according to one aspect of the present disclosure. FIG. 4 is a perspective view of a cord-rubber composite according to one aspect of the present disclosure. FIG. 5 is a cross-sectional view of a tire according to one aspect of the present disclosure. FIG. 6 is an explanatory diagram of a method for evaluating bending rigidity. FIG. 7 is an explanatory diagram of a method for evaluating package bending rigidity. FIG. 8 is an explanatory diagram of the arrangement of steel cords within a cord-rubber composite used for evaluating package bending rigidity. FIG. 9 is an explanatory diagram of an evaluation method for evaluating curvature. FIG. 10 is an explanatory diagram of a method for evaluating position accuracy.

[Problems that this disclosure seeks to solve]
In order to improve the fuel efficiency of automobiles, there is a growing demand for lighter tires and lower rolling resistance. One way to reduce the weight of tires is to reduce the thickness of the tire belt layer. For this reason, studies are being conducted to reduce the diameter of the steel cord used in the belt layer of tires.

However, when the diameter of the steel cord is reduced, the sheet-shaped cord-rubber composite used for the belt layer may become curved. For this reason, there has been a problem that productivity in manufacturing products such as tires is reduced.

Furthermore, when the diameter of the steel cord is made smaller, the position of the steel cord within the cord-rubber composite tends to vary, and in order to embed the steel cord within the rubber, the rubber of the cord-rubber composite must be made thicker. In some cases, it was not possible to make the belt layer thinner.

Therefore, an object of the present disclosure is to provide a steel cord that suppresses curvature when formed into a cord-rubber composite and has excellent positional accuracy within the cord-rubber composite.
[Effects of this disclosure]
According to the present disclosure, it is possible to provide a steel cord that suppresses curvature when formed into a cord-rubber composite and has excellent positional accuracy within the cord-rubber composite.

[Description of embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements are given the same reference numerals, and the same description will not be repeated.

(1) The steel cord according to one aspect of the present disclosure is a single wire steel cord,
Has a brass plating film on the surface,
The cord diameter is 0.25 mm or more and 0.42 mm or less,
The average value of the coil diameter measured at three locations is 500 mm or more and 600 mm or less, and the variation width of the coil diameter measured at the three locations is 50 mm or less,
Torsion per 6m is within ±1 turn.

The copper contained in the brass plating film reacts with sulfur (S) contained in the rubber when a steel cord is embedded in rubber to form a cord-rubber composite or the like. Then, an adhesive layer containing copper sulfide (Cu ₂ S), which is a reaction product, is generated in the rubber near the interface between the steel cord and the rubber.

The produced adhesive layer can enhance the initial adhesion performance between the steel cord and rubber.

Further, it is thought that the zinc contained in the brass plating film promotes and controls the reaction that forms the adhesive layer.

By setting the cord diameter of the steel cord to 0.42 mm or less, when applied to a cord-rubber composite, the thickness of the cord-rubber composite can be reduced. Therefore, the weight of the tire including the cord-rubber composite can be reduced. By setting the cord diameter to 0.25 mm or more, the tensile strength of the steel cord can be increased. Therefore, when manufacturing cord-rubber composites and tires, the number of steel cords required to satisfy the required characteristics such as bending rigidity can be reduced, increasing the productivity of cord-rubber composites, etc. can be enhanced. In addition, by setting the cord diameter to 0.25 mm or more, the number of steel cords required when manufacturing cord-rubber composites etc. can be suppressed, so it is possible to maintain sufficient spacing between the steel cords. A sufficient amount of rubber can be placed between the steel cords. Therefore, the adhesion between the steel cord and the rubber can be improved, and the durability of the cord-rubber composite and the tire can be increased.

By setting the average value of the coil diameter to 500 mm or more, when the steel cord is applied to the cord-rubber composite, it is possible to suppress the cord-rubber composite from curving. Therefore, productivity can be increased when manufacturing products such as tires using the cord-rubber composite.

By setting the average value of the coil diameter to 600 mm or less, the steel cord becomes difficult to twist, and when applied to a cord-rubber composite, the positioning accuracy of the steel cord within the cord-rubber composite can be improved. Therefore, in order to bury the steel cord, the thickness of the rubber placed around the steel cord can be suppressed, and the weight of the cord-rubber composite and the tire can be reduced.

Setting the variation width of the coil diameter to 50 mm or less means that the coil diameter is uniform for the steel cord. Therefore, the characteristics of a cord-rubber composite or a tire manufactured using the steel cord according to one embodiment of the present disclosure can be made uniform and stable.

Setting the torsion per 6 m to within ±1 times, that is, from -1 times to +1 times, means that twisting along the length of the steel cord 10 can be suppressed. Therefore, when the steel cord of this embodiment is used in a cord-rubber composite, it is possible to prevent force from being applied to the rubber arranged around the steel cord so as to cause it to rotate about the steel cord as the rotation axis. . As a result, the cord-rubber composite is prevented from bending, and the positional accuracy of the steel cord is also improved.

(2) In (1), the brass plating film may contain one or more selected from cobalt, nickel, tin, iron, and manganese.

The additive elements cobalt, nickel, tin, iron, and manganese have a greater tendency to ionize than copper. Therefore, if the brass plating film contains additive elements in addition to copper and zinc, the brass plating film can function as sacrificial corrosion protection or make the composite potential of copper and zinc nobler. Therefore, by including the additive element in the brass plating film, the corrosion resistance of the steel cord can be improved.

(3) In (1) or (2), the tensile strength may be 2500 MPa or more and 4500 MPa or less.

Tensile strength refers to the resistance to deformation when a steel cord is pulled. By setting the tensile strength of the steel cord to 2500 MPa or more, the steel cord is necessary to satisfy the characteristics such as bending rigidity required for the cord-rubber composite when applied to the cord-rubber composite. The number of can be suppressed. Therefore, it is possible to reduce the weight of products such as cord-rubber composites and tires.

Furthermore, by setting the tensile strength of the steel cord to 4,500 MPa or less, productivity when manufacturing the steel cord 10 can be increased.

(4) A cord-rubber composite according to one aspect of the present disclosure includes rubber;
The steel cord according to any one of (1) to (3) is embedded in the rubber.

The steel cord contained in the cord-rubber composite according to one aspect of the present disclosure has a small diameter, and when made into a cord-rubber composite, the cord-rubber composite is prevented from curving, and the cord-rubber composite is prevented from curving. Excellent positional accuracy within the complex.

Therefore, the cord-rubber composite according to one embodiment of the present disclosure has excellent handling properties and can improve productivity when manufacturing products such as tires.

Furthermore, in the cord-rubber composite according to one aspect of the present disclosure, since the positional accuracy of the steel cord is high, the thickness of the rubber placed above and below the steel cord, which is necessary for burying the steel cord, can be reduced. can. Therefore, the thickness of the cord-rubber composite can be reduced and the weight can be reduced.

(5) In (4), the bending rigidity is 0.01N or more and 0.05N or less,
Regarding the laminate in which two layers of the cord-rubber composite are laminated, the center of the long side of the laminate is fixed with the short sides located at both ends along the long side of the laminate using a fixing jig. The package curving rigidity may be 2N or more and 10N or less, where the reaction force when the package is displaced by 0.03 mm along the short side is defined as the package curving rigidity.

Bending rigidity is an index showing how difficult a member is to bend and deform, and when the bending rigidity is high, it means that it is difficult to bend and deform. Therefore, by setting the bending rigidity of the cord-rubber composite to 0.01N or more, it means that the cord-rubber composite and products such as tires containing the cord-rubber composite are difficult to bend and deform. You can improve your sexuality.

In addition, by setting the bending rigidity of the cord-rubber composite to 0.05N or less, the number of steel cords placed in the cord-rubber composite can be suppressed, and the cord-rubber composite can contain cord-rubber composites. It is possible to reduce the weight of products such as tires.

By setting the package bending rigidity to 2N or more, it is possible to improve the steering stability when the cord-rubber composite is used in a tire. Further, by setting the package bending rigidity of the cord-rubber composite to 10 N or less, the durability of the cord-rubber composite of this embodiment when used in a tire can be increased.

(6) In (4) or (5), the steel cord may be included so that the number of ends is 30 or more and 60 or less/50 mm.

By setting the ends of the cord-rubber composite to 30/50 mm or more, the gaps between the steel cords included in the cord-rubber composite can be suppressed, and the steel cords can be arranged with high density. For this reason, punching resistance, which is a property that prevents the foreign object from penetrating the cord-rubber composite when the cord-rubber composite is pierced by a foreign object, can be improved. Furthermore, the durability of products such as tires containing the cord-rubber composite can be particularly improved.

By setting the number of ends of the cord-rubber composite to 60/50 mm or less, the number of feeding devices for supplying steel cords can be suppressed and productivity can be increased when manufacturing the cord-rubber composite.

(7) A tire containing the steel cord according to any one of (1) to (3).

The steel cord included in the tire according to one aspect of the present disclosure has a small diameter, and when formed into a cord-rubber composite, suppresses bending of the cord-rubber composite and prevents the cord-rubber composite from bending. Excellent positional accuracy. Therefore, the cord-rubber composite contained in the tire according to one embodiment of the present disclosure can also be made thinner and lighter, and the tire according to one embodiment of the present disclosure can also be made lighter.

[Details of embodiments of the present disclosure]
Specific examples of a steel cord, a cord-rubber composite, and a tire according to an embodiment of the present disclosure (hereinafter referred to as "this embodiment") will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all changes within the meaning and scope equivalent to the scope of the claims.

[Steel cord]
Hereinafter, the steel cord according to this embodiment will be explained based on FIGS. 1, 2, and 3.
(1) Regarding the structure of the steel cord FIG. 1 shows a perspective view of the steel cord of this embodiment. In FIG. 1, the Y-axis is an axis along the length of the steel cord 10. Then, the XZ plane becomes a plane perpendicular to the longitudinal direction of the steel cord 10.

As shown in FIG. 1, the steel cord 10 of this embodiment is a single wire steel cord. A single wire steel cord means that it is composed of a single wire, rather than a twisted wire made of multiple wires twisted together. It is preferable that the steel cord 10 of this embodiment is not twisted along its length. That is, it is preferable that the steel cord 10 of this embodiment is a straight steel cord.

Moreover, it is preferable that the steel cord 10 of this embodiment has a circular shape on a surface perpendicular to the longitudinal direction. The circular shape is not limited to a perfect circle shape, and includes shapes other than a perfect circle such as an ellipse shape.

The steel cord 10 of this embodiment can have a brass plating film 12 on the surface. Specifically, the steel cord 10 can include a wire rod 11 and a brass plating film 12 that covers the wire rod 11.
(wire)
The wire rod 11 can be made of, for example, a steel wire, and a high carbon steel wire can be more preferably used.
(Brass plating film)
The brass plating film 12 can contain copper (Cu) and zinc (Zn). As shown in FIG. 1, the brass plating film 12 can be arranged to cover the side surface 11A of the wire 11.

The copper contained in the brass plating film 12 reacts with sulfur (S) contained in the rubber when the steel cord 10 is embedded in rubber to form a cord-rubber composite or the like. Then, an adhesive layer containing copper sulfide (Cu ₂ S), which is a reaction product, is generated in the rubber near the interface between the steel cord 10 and the rubber.

The produced adhesive layer can improve the initial adhesion performance between the steel cord 10 and rubber. The initial adhesion performance refers to the adhesion performance between the steel cord 10 and rubber immediately after vulcanization during the production of a cord-rubber composite or a tire containing the cord-rubber composite.

It is thought that the zinc contained in the brass plating film 12 promotes and controls the reaction that forms the adhesive layer.

The brass plating film 12 can also contain elements other than copper and zinc. The brass plating film 12 may further include one or more selected from cobalt (Co), nickel (Ni), tin (Sn), iron (Fe), and manganese (Mn).

The additive elements cobalt, nickel, tin, iron, and manganese have a greater tendency to ionize than copper. Therefore, when the brass plating film 12 contains additive elements in addition to copper and zinc, the brass plating film 12 can function as sacrificial corrosion protection or make the combined potential of copper and zinc nobler. Therefore, by including the additive element in the brass plating film 12, the corrosion resistance of the steel cord 10 can be improved.
(2) Characteristics of Steel Cord (2-1) Cord Diameter The steel cord 10 preferably has a cord diameter D10 of 0.25 mm or more and 0.42 mm or less. The cord diameter D10 is more preferably 0.30 mm or more and 0.42 mm or less, even more preferably 0.34 mm or more and 0.38 mm or less, and particularly preferably 0.35 mm or more and 0.37 mm or less.

By setting the cord diameter D10 to 0.42 mm or less, when applied to a cord-rubber composite, the thickness of the cord-rubber composite can be reduced. Therefore, the weight of the tire including the cord-rubber composite can be reduced. By setting the cord diameter D10 to 0.25 mm or more, the tensile strength of the steel cord 10 can be increased. Therefore, when manufacturing cord-rubber composites and tires, the number of steel cords required to satisfy the required characteristics such as bending rigidity can be suppressed, and productivity can be increased. In addition, by setting the cord diameter D10 to 0.25 mm or more, the number of steel cords required when manufacturing cord-rubber composites etc. can be suppressed, allowing sufficient spacing between the steel cords. , a sufficient amount of rubber can be placed between the steel cords. Therefore, the adhesion between the steel cord and the rubber can be improved, and the durability of the cord-rubber composite and the tire can be increased.

The cord diameter D10 is determined by measuring an arbitrary cross section perpendicular to the length of the steel cord 10. In measuring the cord diameter D10, first, two orthogonal diameters D101 and D102 can be measured in a cross section perpendicular to the length of the steel cord 10. Then, the average value of the two diameters D101 and D102 can be set as the cord diameter D10 of the steel cord 10.
(2-2) Regarding coil diameter The steel cord 10 of this embodiment has a thin cord diameter D10 of 0.42 mm or less. When a sheet-shaped cord-rubber composite is formed using such a small-diameter steel cord, the cord-rubber composite may be curved. Furthermore, when forming a sheet-shaped cord-rubber composite, a plurality of steel cords are aligned under a certain tension and embedded in rubber. However, the position of the steel cord may shift until the rubber is sufficiently cured, and the position of the steel cord within the cord-rubber composite may vary. For this reason, even though the steel cord has a small diameter, when making a cord-rubber composite, it is necessary to ensure the thickness of the rubber placed above and below the steel cord in order to embed the steel cord in the rubber. There was a risk that the cord-rubber composite could not be made thinner.

Therefore, the inventor of the present invention conducted a study. As a result, when the steel cord is made small in diameter, the curvature of the cord-rubber composite and the decrease in the positional accuracy of the steel cord in the cord-rubber composite occur when the coil diameter has rarely been paid attention to. found that it was influenced by

Therefore, in the steel cord 10 of this embodiment, it is preferable that the average value of the coil diameters measured at three locations is 500 mm or more and 600 mm or less.

By setting the average value of the coil diameter to 500 mm or more, when the steel cord 10 is applied to the cord-rubber composite, it is possible to suppress the cord-rubber composite from curving. Therefore, productivity can be increased when manufacturing products such as tires using the cord-rubber composite.

By setting the average value of the coil diameter to 600 mm or less, the steel cord 10 becomes difficult to twist, and when applied to a cord-rubber composite, the positioning accuracy of the steel cord 10 within the cord-rubber composite can be improved. Therefore, in order to bury the steel cord 10, the thickness of the rubber placed around the steel cord 10 can be suppressed, and the weight of the cord-rubber composite and the tire can be reduced.

When measuring the coil diameter of the steel cord 10, the steel cord 10 can be repeatedly cut along its length until three cut pieces of the steel cord 10 having the annular portion 21 in contact with the horizontal test stand 20 are formed. .

As shown in FIG. 2, the coil diameter D20 of each cut piece means the diameter of the annular portion 21 that is naturally formed without applying force to each cut piece of the steel cord 10. Therefore, when measuring the coil diameter D20 of each cut piece, the cut piece of the steel cord 10 is left on the horizontal test stand 20. Then, when the annular portion 21 is formed on the test stand 20, two orthogonal diameters D211 and D212 of the annular portion 21 are measured. Next, the average value of the two measured diameters D211 and D212 can be determined to be the coil diameter D20 of each cut piece.

Then, the coil diameter D20 of the three cut pieces having the annular portion 21 in contact with the horizontal test stand 20 is measured, and the average value of the coil diameter of the three cut pieces is calculated from the three cut pieces of the steel cord 10 subjected to the measurement. It can be the average value of the coil diameters measured at the location.

In addition, the difference between the maximum and minimum values of the coil diameter D20 of the three cut pieces measured can be determined, and this can be used as the variation width of the coil diameter measured at three locations for the steel cord 10 subjected to measurement. .

In the steel cord 10 of this embodiment, the variation width of the coil diameter measured at three locations is preferably 50 mm or less, more preferably 40 mm or less.

Setting the variation width of the coil diameter to 50 mm or less means that the coil diameter of the steel cord 10 of this embodiment is uniform. Therefore, the characteristics of a cord-rubber composite or a tire manufactured using the steel cord of this embodiment can be made uniform and stable.

Although the lower limit of the variation width of the coil diameter is not particularly limited, it is preferably 0 mm or more, and more preferably 10 mm or more from the viewpoint of increasing productivity.

The variation width of the coil diameter is preferably, for example, 0 mm or more and 50 mm or less, and more preferably 10 mm or more and 40 mm or less.
(2-3) Torsion The steel cord 10 of this embodiment preferably has a torsion of within ±1 turn per 6 m, more preferably within ±0.5 turn.

Torsion means the number of rotations of the steel cord when one end of the steel cord 10 is free.

Setting the torsion per 6 m to within ±1 times, that is, from -1 times to +1 times, means that twisting along the length of the steel cord 10 can be suppressed. Therefore, when the steel cord of this embodiment is made into a cord-rubber composite, it is possible to prevent force from being applied to the rubber disposed around the steel cord so as to cause it to rotate about the steel cord as the rotation axis. As a result, the cord-rubber composite is prevented from bending, and the positional accuracy of the steel cord is also improved.

Torsion can be evaluated using the same procedure as for residual torsion in JIS G 3510 (1992). When measuring, observe the end of the steel cord bent at a right angle, which is the reference point.If the steel cord rotates clockwise (clockwise), it is marked + (plus), and if the steel cord rotates counterclockwise (counterclockwise), it is marked + (plus). ) is defined as - (minus).
(2-4) Regarding tensile strength The steel cord 10 preferably has a tensile strength of 2,500 MPa or more and 4,500 MPa or less, more preferably 3,000 MPa or more and 4,200 MPa or less, and even more preferably 3,150 MPa or more and 3,500 MPa or less.

Tensile strength refers to the difficulty of deformation when the steel cord 10 is pulled. By setting the tensile strength of the steel cord 10 to 2500 MPa or more, when applied to a cord-rubber composite, the steel cord 10 is required to satisfy the characteristics such as bending rigidity required for the cord-rubber composite. The number of cords can be reduced. Therefore, it is possible to reduce the weight of products such as cord-rubber composites and tires.

Further, by setting the tensile strength of the steel cord 10 to 4,500 MPa or less, productivity in manufacturing the steel cord 10 can be increased.
(3) Regarding the manufacturing method of steel cord,
The method for manufacturing the steel cord of this embodiment is not particularly limited. For example, it can be manufactured by drawing a cord base material with a brass plating film arranged on the surface of the base material using dies or rolls.

Specifically, for example, as shown in FIG. 3, the cord base material 30 is drawn through dies 311 and 312. Next, the cord base material 30 wire-drawn by the die is pressed by the roll 32 to further wire-draw it to a desired cord diameter.

As for the rolls 32, as shown in FIG. 3, upper rolls 321A, 321B, and 321C can be arranged above the cord base material 30 to be wire-drawn, and lower rolls 322A and 322B can be arranged below. Then, the cord base material 30 can be pressed from above and below by the upper rolls 321A, 321B, 321C and the lower rolls 322A, 322B.

Note that the number and arrangement of dice, the shape, number, and arrangement of rolls constituting the roll 32 are not limited to the example shown in FIG. 3. For example, it is possible to conduct a preliminary test and select the shape, arrangement and number of dies and rolls, the pressure to be applied to the cord base material, etc., depending on the average value, variation width, etc. of the coil diameter of the steel cord manufactured in the preliminary test. preferable.

For example, regarding the shape of the roll, the shape of the grooves provided in the roll can be selected. The shape of the groove provided in the roll may be, for example, a shape with a constant curvature in a cross section perpendicular to the longitudinal direction of the groove. Further, the grooves provided in the upper roll and the lower roll arranged adjacently along the conveyance path of the cord base material 30 are made to have a constant curvature in a cross section perpendicular to the longitudinal direction of the groove, and the steel to be manufactured is It is also possible to vary the cord diameter by up to 30% of the cord diameter. By selecting the shapes of the grooves provided on the upper roll and the lower roll, it is possible to improve the controllability of parameters such as the coil diameter of the steel cord to be manufactured.

In addition, in order to convey the cord base material 30 when drawing the cord base material 30, the arrangement of rolls arranged on the conveyance line (pass line) and the pressure applied to the cord base material 30 by the rolls are adjusted. This allows you to adjust the torsion of the resulting steel cord. Specifically, for example, torsion can be reduced by adjusting the position of the rolls so that the pressure applied to the outer surface of the cord base material 30 is uniform regardless of the location of the outer surface of the cord base material 30. It is preferable from the viewpoint of
[Cord-rubber composite]
FIG. 4 shows a perspective view of the cord-rubber composite 40 of this embodiment. In FIG. 4, the Y-axis is an axis along the length of the steel cord 10. Then, the XZ plane becomes a plane perpendicular to the longitudinal direction of the steel cord 10.

As shown in FIG. 4, the cord-rubber composite 40 of this embodiment includes rubber 41 and the steel cord 10 of this embodiment embedded in the rubber 41.
(1) Regarding the members contained in the cord-rubber composite (1-1) Steel cord The cord-rubber composite 40 can include a plurality of steel cords 10 according to the present disclosure. The steel cords 10 contained in the cord-rubber composite 40 can be arranged such that the length of each steel cord 10 is along the Y axis in FIG. The plurality of steel cords 10 can be arranged along the width of the cord-rubber composite 40, that is, along the X axis in FIG.

It is preferable that the plurality of steel cords 10 are arranged parallel to each other. Parallel does not mean parallel in a strict sense, but means that the steel cords 10 are arranged in parallel.

Since the details of the steel cord 10 have already been explained, the explanation will be omitted.
(1-2) Rubber The rubber 41 of the cord-rubber composite 40 can be manufactured by molding a rubber composition and, if necessary, vulcanizing it.

The specific composition of the rubber can be selected depending on the use of various products such as tires to which the cord-rubber composite 40 is applied, the required characteristics, etc., and is not particularly limited. The rubber can include, for example, a rubber component, sulfur, and a vulcanization accelerator.

The rubber component preferably contains 60% by mass or more, and preferably contains 70% by mass or more of one or more types selected from, for example, natural rubber (NR) and isoprene rubber (IR). is more preferable, and it is even more preferable to contain 100% by mass.

This increases the breaking strength of the cord-rubber composite 40 and the tire by setting the proportion of one or more types of rubber selected from natural rubber and isoprene rubber in the rubber component to 60% by mass or more. This is because it is possible and preferable.

Rubber components used in combination with natural rubber or isoprene rubber include, for example, styrene-butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and butyl rubber (IIR). , acrylonitrile-butadiene rubber (NBR).

Sulfur is not particularly limited, but for example, sulfur commonly used as a vulcanizing agent in the rubber industry can be used.

Although the sulfur content of the rubber is not particularly limited, it is preferably, for example, 5 parts by mass or more and 8 parts by mass or less based on 100 parts by mass of the rubber component.

This is because by setting the proportion of sulfur to 5 parts by mass or more with respect to 100 parts by mass of the rubber component, it is possible to increase the crosslinking density of the obtained rubber, and in particular to increase the adhesive strength between the steel cord and the rubber. In addition, it is preferable to set the ratio of sulfur to 8 parts by mass or less based on 100 parts by mass of the rubber component, because sulfur can be particularly uniformly dispersed in the rubber and blooming can be suppressed. .

The vulcanization accelerator is not particularly limited, but for example, N,N'-dicyclohexyl-2-benzothiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzo Sulfenamide accelerators such as thiazolylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide are preferably used. If desired, thiazole accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide, tetrabenzylthiuram disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrakis(2-ethylhexyl)thiuram disulfide may be used. , thiuram type accelerators such as tetramethylthiuram monosulfide may also be used.

The rubber composition used for the cord-rubber composite 40 of this embodiment can be produced by kneading raw materials such as rubber components, heating and extruding.

The rubber of the cord-rubber composite 40 of the present embodiment preferably contains one or more types selected from elemental cobalt and compounds containing cobalt.

Examples of the cobalt-containing compound include organic acid cobalt and inorganic acid cobalt.

As the organic acid cobalt, for example, one or more selected from cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosin acid, cobalt versatate, cobalt tall oil acid, etc. can be preferably used. Note that the organic acid cobalt may be a complex salt in which part of the organic acid is replaced with boric acid.

As the inorganic acid cobalt, for example, one or more selected from cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate can be preferably used.

In particular, it is more preferable that the rubber of the cord-rubber composite 40 of this embodiment contains organic acid cobalt. This is because by containing organic acid cobalt, the initial adhesion performance between the steel cord and the rubber can be particularly improved.

In addition, according to the studies of the inventor of the present invention, by adding cobalt to rubber, the proportion of copper sulfide (Cu ₂ S) in the adhesive layer can be increased, and the adhesive force between the steel cord and the rubber can be increased. can be increased. When an organic acid cobalt is used as the cobalt to be added, this tendency becomes remarkable. Therefore, it is preferable that the rubber of the cord-rubber composite 40 of this embodiment contains cobalt, especially organic acid cobalt, and thereby the cord-rubber composite 40 and tire can have particularly excellent durability. can.

Further, the rubber can contain any other components other than the above-mentioned rubber components, sulfur, vulcanization accelerator, cobalt, etc. The rubber may also contain well-known additives for rubber, such as reinforcing agents (carbon black, silica, etc.), waxes, anti-aging agents, and the like.
(2) Regarding the characteristics of the cord-rubber composite (2-1) Ends The number of steel cords 10 included in the cord-rubber composite 40 of this embodiment is not particularly limited, and the cord-rubber composite 40 and the cord- It can be selected depending on the characteristics required of the tire including the rubber composite 40. Here, the number of steel cords present per 50 mm width of the cord-rubber composite 40 in the cross section perpendicular to the length of the steel cord of the cord-rubber composite 40 of this embodiment is defined as ends. Therefore, in this specification, the unit of ends is "ends/50 mm". In this case, the ends are preferably, for example, 30/50 mm or more and 60/50 mm or less, more preferably 36/50 mm or more and 60/50 mm or less, and 40/50 mm or more and 60/50 mm or less. It is more preferable that

By setting the ends of the cord-rubber composite 40 of this embodiment to 30 pieces/50 mm or more, the gaps between the steel cords 10 included in the cord-rubber composite 40 can be suppressed, and the steel cords can be arranged with high density. . For this reason, punching resistance, which is a property that prevents the foreign object from penetrating the cord-rubber composite when the cord-rubber composite is pierced by a foreign object, can be improved. Furthermore, the durability of products such as tires containing the cord-rubber composite 40 can be particularly improved.

By setting the ends of the cord-rubber composite 40 of this embodiment to 60 pieces/50 mm or less, the number of feeding devices for supplying steel cords can be suppressed when manufacturing the cord-rubber composite, and production You can enhance your sexuality.
(2-2) Bending rigidity The cord-rubber composite 40 of this embodiment preferably has a bending rigidity of 0.01N or more and 0.05N or less, more preferably 0.01N or more and 0.03N or less. .

Bending rigidity is an index showing how difficult a member is to bend and deform, and when the bending rigidity is high, it means that it is difficult to bend and deform. Therefore, by setting the bending rigidity of the cord-rubber composite 40 to 0.01N or more, it means that the cord-rubber composite and products such as tires containing the cord-rubber composite are difficult to bend and deform. Can increase durability.

Furthermore, by setting the bending rigidity of the cord-rubber composite 40 to 0.05N or less, the number of steel cords arranged in the cord-rubber composite 40 can be suppressed, and the cord-rubber composite It is possible to reduce the weight of products such as tires, including the body.
(2-3) Package bending rigidity Regarding the laminate in which two layers of the cord-rubber composite of this embodiment are laminated, the short sides located at both ends along the long sides of the laminate are fixed with a fixing jig. The package bending rigidity is defined as the reaction force when the center of the long side of the laminate is displaced by 0.03 mm along the short side.

The package bending rigidity of the cord-rubber composite of the present embodiment is preferably 2N or more and 10N or less, more preferably 2.5N or more and 5N or less.

Package bending stiffness is a characteristic that corresponds to cornering power when a cord-rubber composite is used in a tire. Specifically, the characteristics correspond to the handling stability when the cord-rubber composite is used in a tire.

By setting the package bending rigidity of the cord-rubber composite of this embodiment to 2N or more, it is possible to improve the steering stability when the cord-rubber composite of this embodiment is used in a tire. Furthermore, by setting the package bending rigidity of the cord-rubber composite of this embodiment to 10 N or less, the durability of the cord-rubber composite of this embodiment when used in a tire can be increased.

The steel cord 10 contained in the cord-rubber composite 40 of this embodiment has a small diameter, and when it is made into the cord-rubber composite 40, it suppresses the cord-rubber composite 40 from curving, and prevents the cord-rubber composite 40 from curving. Excellent positional accuracy within the rubber composite 40.

Therefore, the cord-rubber composite 40 according to the present embodiment has excellent handling properties when manufacturing products such as tires, and can improve productivity.

Furthermore, in the cord-rubber composite 40 of this embodiment, the positional accuracy of the steel cord 10 is high. Therefore, the thickness of the rubber 41 disposed above and below the steel cord 10, which is necessary for embedding the steel cord 10, can be reduced, that is, the thickness T411 and the thickness T412 in FIG. 4. As a result, the thickness T40 of the cord-rubber composite 40 can also be reduced, and weight reduction can be achieved.
(3) Method for manufacturing cord-rubber composite The method for manufacturing the cord-rubber composite of this embodiment is not particularly limited. For example, a plurality of steel cords arranged in parallel are placed in rubber to form desired ends. It can be manufactured by burying it in

The cord-rubber composite of this embodiment can have, for example, a reel installation process, a withdrawal process, an arrangement process, and an embedding process. The outline of each process will be explained below.
(Reel installation process)
In the reel installation step, in the belt layer of the cord-rubber composite, a plurality of reels can be installed in the steel cord supply device, the number of which corresponds to the number of cords to be embedded in the rubber. A steel cord according to one aspect of the present disclosure is wound around each reel. The steel cord supply device is a device that controls the rotation of the reels and supplies steel cord wound onto each reel from each reel. The steel cord supply device is sometimes called a reel supply or the like.
(Drawing process)
In the drawing process, steel cords can be drawn out from each prepared reel by a steel cord supply device, and transported and supplied to the arranging process.

Since the steel cord according to one aspect of the present disclosure is wound around the reel, the average value of the coil diameter of the drawn-out steel cord is within a predetermined range. For this reason, by applying tension to the steel cords during the arrangement process and the burying process in accordance with the average value of the coil diameter, variations in the position of the steel cords can be suppressed.

In addition, after the steel cord is pulled out from each reel in the drawing process, a roll with a groove with a constant curvature in a cross section perpendicular to the groove length is placed on the conveyance path of the steel cord, and tension is applied to the steel cord. You can also add By placing a roll with grooves of a predetermined shape on the conveyance path of the steel cord and applying tension to the steel cord, it is possible to reduce and eliminate the wire curls that the steel cord had. Therefore, variations in the position of the steel cord can be particularly suppressed, and the cord-rubber composite can be made thinner.
(Array process)
In the arranging step, a plurality of steel cords pulled out from the reel can be arranged in a line in a cross section perpendicular to the length of the steel cords.

In the arranging step, for example, a plurality of steel cords can be arranged in a line using an arranging device.

Although the configuration of the arrangement device is not particularly limited, for example, in order to arrange the steel cords in a line, it may have a guide plate provided with a groove through which the steel cords are passed.

In the arranging step, the positions of the steel cords can be further corrected and arranged using grooved rolls if necessary.
(burying process)
In the embedding process, a plurality of steel cords can be buried in rubber to produce a cord-rubber composite.

Specifically, for example, a cord-rubber composite can be produced by placing a plurality of steel cords between rubber using a calender roll and performing calender treatment. When the cord-rubber composite has a plurality of belt layers, the steps from the reel installation process to the embedding process can be performed for each belt layer.

〔tire〕
The tire in this embodiment will be explained based on FIG. 5.

The tire of this embodiment can include the steel cord of this embodiment.

FIG. 5 shows a cross-sectional view of the tire 50 according to the present embodiment in a plane perpendicular to the outer circumference. In FIG. 5, only the portion to the left of the CL (center line) is shown, but with the CL as the axis of symmetry, the same structure continues on the right side of the CL.

As shown in FIG. 5, the tire 50 includes a tread portion 51, a sidewall portion 52, and a bead portion 53.

The tread portion 51 is a portion that comes into contact with the road surface. The bead portion 53 is provided at a position closer to the inner diameter of the tire 50 than the tread portion 51. The bead portion 53 is a portion that contacts the rim of a vehicle wheel. The sidewall portion 52 connects the tread portion 51 and the bead portion 53. When the tread portion 51 receives an impact from the road surface, the sidewall portion 52 elastically deforms and absorbs the impact.

The tire 50 includes an inner liner 54, a carcass 55, a belt layer 56, and a bead wire 57.

The inner liner 54 is made of rubber and seals the space between the tire 50 and the wheel.

The carcass 55 forms the frame of the tire 50. The carcass 55 is made of organic fibers such as polyester, nylon, rayon, or steel cord, and rubber.

The bead wire 57 is provided at the bead portion 53. The bead wire 57 receives the tensile force acting on the carcass.

The belt layer 56 tightens the carcass 55 and increases the rigidity of the tread portion 51. In the example shown in FIG. 5, the tire 50 has two belt layers 56.

The belt layer 56 includes a plurality of steel cords and rubber. A plurality of steel cords are arranged in parallel in a row. That is, belt layer 56 can include a cord-rubber composite according to the present disclosure.

The steel cord included in the tire of this embodiment has a small diameter, and when it is made into a cord-rubber composite, it suppresses the cord-rubber composite from curving and improves the positional accuracy within the cord-rubber composite. Excellent. Therefore, the cord-rubber composite contained in the tire of this embodiment can also be made thinner and lighter, and the tire of this embodiment can also be made lighter.

Although the embodiments have been described in detail above, they are not limited to specific embodiments, and various modifications and changes can be made within the scope of the claims.

The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.
(Evaluation method)
(1) Evaluation method of steel cord The evaluation method of the steel cord produced in the following experimental example will be explained.
(1-1) Cord diameter A steel cord to be evaluated was embedded in a transparent resin, and a sample was cut out so that the surface (cross section) perpendicular to the length of the steel cord was exposed.

In a cross section perpendicular to the length of the cut steel cord 10, two orthogonal diameters D101 and D102 were measured (see FIG. 1). The average value of the two diameters D101 and D102 was defined as the cord diameter D10 of the steel cord 10.
(1-2) Average value of coil diameter, variation width of coil diameter When measuring the coil diameter, until three cut pieces of the steel cord 10 having the annular part 21 in contact with the horizontal test stand 20 are formed. , the steel cord 10 was repeatedly cut along its length.

Next, as shown in FIG. 2, the cut pieces of the steel cord 10 were left on a horizontal test stand 20. Regarding the cut piece in which the annular part 21 was formed on the test stand 20, two orthogonal diameters D211 and D212 of the annular part 21 were measured. Next, the average value of the two measured diameters D211 and D212 was determined, and this was determined as the coil diameter D20 of the measured cut piece.

The average value of the coil diameter D20 of the three measured cut pieces was taken as the average value of the coil diameters measured at three locations for the steel cord 10 subjected to the measurement.

In addition, the difference between the maximum value and the minimum value of the coil diameter D20 of the three measured cut pieces was determined, and this was determined as the variation width of the coil diameter measured at three locations for the steel cord 10 subjected to the measurement.
(1-3) Torsion Torsion was evaluated using the same procedure as for residual torsion in JIS G 3510 (1992).

When measuring, observe the end of the steel cord bent at a right angle, which is the reference point.If the steel cord rotates clockwise (clockwise), it is marked + (plus), and if the steel cord rotates counterclockwise (counterclockwise), it is marked + (plus). ) is defined as - (minus).
(1-4) Tensile strength Tensile strength (tensile strength) was measured in accordance with JIS Z 2241 (2022).
(2-1) Bending rigidity As shown in FIG. 6, the bending rigidity of the cord-rubber composite 40 was evaluated by a three-point bending test.

Specifically, a first end 601 and a second end 602, which are width ends of the cord-rubber composite 40, were supported from below by support jigs 611 and 612. Next, the midpoint between the support jig 611 and the support jig 612 was pressed downward as shown by the block arrow 62 with the press jig 613 .

Therefore, the distance L401 and the distance L402 in FIG. 4 are equal. The distance L401 means the distance between the point where the cord-rubber composite 40 contacts the support jig 611 and the point where the cord-rubber composite 40 contacts the pressing jig 613. The distance L402 means the distance between the point where the cord-rubber composite 40 contacts the support jig 612 and the point where the cord-rubber composite 40 contacts the pressing jig 613.

Then, the reaction force when the location pressed by the pressing jig 613 was displaced by 0.1 mm along the block arrow 62 was measured.

For the bending rigidity test, the cord-rubber composites prepared in each experimental example were cut into test pieces of 30 mm x 1.2 mm. The distance between the support jig 611 and the support jig 612 was 30 mm.
(2-2) Package bending rigidity As shown in FIG. 7, the first cord-rubber composite 401 and the second cord-rubber composite 402, which are the cord-rubber composites 40 produced in each experimental example, are A stacked laminate 70 was prepared. The laminate 70 had a width W70 of 30 mm and a depth D70 of 10 mm.

Next, the short sides 701 and 702 located at both ends along the long side 703 of the laminate 70 were fixed using a fixing jig 711 and a fixing jig 712. The fixing jig 711 and the fixing jig 712 fixed the entire short sides 701 and 702 of the laminate 70 along the short sides 701 and 702.

Then, the center of the long side of the laminate 70, that is, the center between both ends fixed with the fixing jigs 711 and 712, is pulled by the pulling jig 72 along the short sides 701 and 702, that is, along the block arrow 73. The reaction force when the package was pulled by 0.03 mm was defined as the package bending rigidity.

Therefore, the distance L701 and the distance L702 in FIG. 7 are equal.

Note that the steel cords 10 are arranged in the first cord-rubber composite body 401 and the second cord-rubber composite body 402 that constitute the laminate 70 so as to be inclined with respect to the short sides 701 and 702.

As shown in FIG. 8, the steel cord 10 is arranged in the first cord-rubber composite 401 so that the angle θ1 with respect to the short side 702 is 30 degrees. Further, the steel cord 10 is arranged in the second cord-rubber composite 402 so that the angle θ2 with respect to the short side 702 is -30 degrees. Note that in FIG. 8, for convenience of drawing, angles θ1 and θ2 are shown as angles with respect to a straight line parallel to the short side 702 shown in the center of FIG.

FIG. 8 is a top view of the laminate 70, which is an enlarged view of the vicinity of the fixing jig 712. Shown with body parts removed.
(2-3) Curvature Evaluation The cord-rubber composite produced in the following experimental example was cut to a size of 1 m x 1 m and subjected to evaluation.

As shown in FIG. 9, the evaluation was carried out by placing the cord-rubber composite 40 cut to the above size on the upper surface 90A of the test stand 90, and measuring the maximum height H40 without applying any external force.

The maximum height H40 was evaluated as A when it was less than 5 mm, B when it was 5 mm or more and less than 20 mm, and C when it was 20 mm or more.

When the evaluation is A, it means that the degree to which the cord-rubber composite is able to suppress curving is the highest, and the evaluation decreases in the order of B and C. If the evaluation is A or B, it means that the degree of curvature of the cord-rubber composite has been sufficiently suppressed.
(2-4) Positional Accuracy As shown in FIG. 10, the cord-rubber composite 40 produced in each experimental example was placed on a flat test stand 100. At this time, the steel cord 10 was installed so that a measurement area in which five steel cords 101, 102, 103, 104, and 105 were consecutively arranged in a cross section perpendicular to the length of the steel cord 10 was exposed.

Next, a weight (not shown) is installed on the surface 110 of the cord-rubber composite 40 opposite to the surface in contact with the test stand 100 so as to apply a load of 0.05 kg/mm ² per unit area. The body 40 was pressed against the test stand 100. As the weight, a plate-shaped weight whose surface facing the cord-rubber composite 40 to be evaluated had the same area as the surface 110 of the cord-rubber composite 40 was used.

Note that the cord-rubber composite 40 was cut so that both the surface in contact with the test stand 100 and the surface 110 in contact with the weight were squares, and used for the test.

Among the steel cords 10 included in the cord-rubber composite 40, a reference line L parallel to the top surface of the test stand 100 is drawn so as to pass through the center of the steel cord 101 placed at the end of the cord-rubber composite 40. Set.

Next, the width of variation along the thickness of the cord-rubber composite 40 was measured for each of the steel cords 102, 103, 104, and 105 other than the standard steel cord 101.

The variation width of each steel cord 10 was determined by measuring the distance between the reference line L and the center of each steel cord 10 along the thickness of the cord-rubber composite 40. In FIG. 10, the center is indicated by a black dot. The variation width of the steel cord 102 is L102, the variation width of the steel cord 103 is L103, the variation width of the steel cord 104 is L104, and the variation width of the steel cord 105 is L105.

The average value of the variation widths L102, L103, L104, and L105 was defined as the variation width of the position of the steel cord 10 of the cord-rubber composite 40.

It was evaluated as A when the variation width of the position of the steel cord 10 was less than 0.3 mm, B when it was 0.3 mm or more and less than 0.5 mm, and C when it was 0.5 mm or more.

When the evaluation is A, it means that variations in the position of the steel cord 10 of the cord-rubber composite can be suppressed and the positional accuracy is the highest, and the evaluation decreases in the order of B and C. If the evaluation is A or B, the positional accuracy of the steel cord in the cord-rubber composite is sufficiently high.

The manufacturing conditions of the steel cord in each experimental example will be explained below. Examples include Experimental Examples 1 to 3, Experimental Examples 6 to 9, Experimental Examples 12 to 16, and Experimental Examples 19 to 23. Experimental Examples 4, 5, 10, 11, 17, and 18 are comparative examples.
[Experiment example 1]
(Manufacture of steel cord)
A steel cord was manufactured using the apparatus shown in FIG.

A steel cord was manufactured by preparing a cord base material 30 in which a copper layer and a zinc layer were formed on the surface of a steel base material by plating, and performing wire drawing.

As shown in FIG. 3, in the wire drawing process, the cord base material was first passed through dies 311 and 312 to gradually reduce the cord diameter. Next, the cord base material 30 is further passed between rolls 32 having grooves on the surface in contact with the steel cord to process the cord diameter, coil diameter, and torsion to desired values, thereby forming a steel cord. was manufactured. The number and pressure of the rolls 32, and the shape of the grooves were selected depending on the desired cord diameter, the average value of the coil diameter, and the variation width of the coil diameter. The groove provided in the roll 32 had a shape with constant curvature in a cross section perpendicular to the longitudinal direction of the groove. Further, the arrangement of the rolls disposed on the conveyance path of the cord base material 30 for conveying the cord base material 30 and the pressure applied to the cord base material 30 were selected depending on the desired torsion. In the other experimental examples below, the conditions described here were selected based on the results of preliminary tests conducted in advance in order to obtain the desired values for the cord diameter, average coil diameter, variation width of the coil diameter, and torsion. , is being adjusted.

The obtained steel cord was evaluated. The evaluation results are shown in Table 1.
(Production of cord-rubber composite)
A plurality of steel cords were embedded in rubber so as to have the ends shown in Table 1, and a cord-rubber composite was manufactured.

Specifically, a cord-rubber composite was produced by placing a plurality of steel cords between rubber using a calender roll and performing calender treatment.

The above rubber was manufactured from a rubber composition containing a rubber component and an additive. The rubber composition contains 100 parts by mass of natural rubber as a rubber component. The rubber composition contains, as additives, 60 parts by mass of carbon black, 7 parts by mass of sulfur, 0.5 parts by mass of a vulcanization accelerator, 8 parts by mass of zinc oxide, and 100 parts by mass of the rubber component. Cobalt stearate is contained as cobalt acid in a proportion of 2 parts by mass.

The cord-rubber composite was prototyped in advance using the steel cord of this experimental example, and the range of variation in the position of the steel cord 10 of the cord-rubber composite 40 was measured in the position accuracy evaluation method. In addition, the rubber thickness was determined by adding a preset thickness constant to allow the steel cord 10 to be buried to the variation width of the position of the steel cord 10 in the measured cord-rubber composite 40. .

When manufacturing the cord-rubber composite of this experimental example, manufacturing conditions were selected so that the thickness of the rubber disposed above and below the steel cord 10 was the same as the thickness determined in advance. In other experimental examples below, the rubber thickness was determined in advance using the steel cord produced in each experimental example, and was used when manufacturing the cord-rubber composite.

Note that the thicknesses of the rubbers disposed above and below the steel cord 10 correspond to the thicknesses T411 and T412 in FIG. 4, respectively.

The obtained cord-rubber composite was evaluated. The evaluation results are shown in Table 1.
[Experiment example 2 to experiment example 18]
When manufacturing the steel cord, each experimental example was processed so that the cord diameter, the average value of the coil diameter, the variation width of the coil diameter, and the torsion had the desired values.

A steel cord and a cord-rubber composite were produced and evaluated under the same conditions as Experimental Example 1 except for the above points. The evaluation results are shown in Tables 1 and 2.
[Experiment Example 19 to Experiment Example 22]
When manufacturing the steel cord, each experimental example was processed so that the cord diameter, the average value of the coil diameter, the variation width of the coil diameter, and the torsion had the desired values.

Furthermore, when producing the cord-rubber composite, the ends were changed to the values shown in Table 2. Steel cords and cord-rubber composites were produced and evaluated under the same conditions as Experimental Example 2 except for the above points. The evaluation results are shown in Table 1.

A steel cord and a cord-rubber composite were produced and evaluated under the same conditions as Experimental Example 1 except for the above points. The evaluation results are shown in Table 2.
[Experiment example 23]
A cord base material 30 was used in which a copper layer, a cobalt layer, and a zinc layer were formed on the surface of a steel base material by plating. Then, when manufacturing the steel cord, processing was performed so that the cord diameter, the average value of the coil diameter, the variation width of the coil diameter, and the torsion became desired values.

A steel cord and a cord-rubber composite were produced and evaluated under the same conditions as Experimental Example 1 except for the above points. The evaluation results are shown in Table 2.

表１、表２によると、コード径、コイル径の平均値、コイル径のばらつき幅、トーションが所定の範囲内の実験例１から実験例３、実験例６から実験例９、実験例１２から実験例１６、実験例１９から実験例２３のスチールコードを用いたコード－ゴム複合体は、湾曲性評価、位置精度の評価がＡまたはＢになることを確認できた。すなわち、これらの実験例のスチールコードは、コード－ゴム複合体とした場合に、湾曲することを防止でき、コード－ゴム複合体内での位置精度に優れることを確認できた。

According to Tables 1 and 2, from Experimental Examples 1 to 3, from Experimental Examples 6 to 9, and from Experimental Example 12, the cord diameter, the average value of the coil diameter, the variation range of the coil diameter, and the torsion are within the predetermined ranges. It was confirmed that the cord-rubber composites using the steel cords of Experimental Examples 16, 19 to 23 had evaluations of bendability and position accuracy of A or B. That is, it was confirmed that the steel cords of these experimental examples were able to prevent bending when made into a cord-rubber composite, and had excellent positional accuracy within the cord-rubber composite.

10 Steel cord 11 Wire rod 11A Side surface 12 Brass plating film D10 Cord diameter D101, D102 Diameter 20 Test stand 21 Annular part D20 Coil diameter D211, D212 Diameter 30 Cord base material 311, 312 Die 32 Roll 321A, 321B, 321C Upper roll 322A, 322B Lower roll 40 Cord-rubber composite 41 Rubber T411, T412 Thickness T40 Thickness CL Center line 50 Tire 51 Tread portion 52 Sidewall portion 53 Bead portion 54 Inner liner 55 Carcass 56 Belt layer 57 Bead wire 601 First end portion 602 Second end 611, 612 Supporting jig 613 Pressing jig 62 Block arrows L401, L402 Distance 401 First cord-rubber composite 402 Second cord-rubber composite 70 Laminated body W70 Width D70 Depth 701, 702 Short side 703 Long sides L701, L702 Distances 711, 712 Fixing jig 72 Traction jig 73 Block arrows θ1, θ2 Angle 90 Test stand 90A Top surface H40 Maximum height 100 Test stand 101, 102, 103, 104, 105 Steel cord 110 Surface L Reference line L102, L103, L104, L105 variation width

Claims (7)

It is a single wire steel cord,
Has a brass plating film on the surface,
The cord diameter is 0.25 mm or more and 0.42 mm or less,
The average value of the coil diameter measured at three locations is 500 mm or more and 600 mm or less, and the variation width of the coil diameter measured at the three locations is 50 mm or less,
Steel cord with torsion within ±1 turn per 6m. The steel cord according to claim 1, wherein the brass plating film contains one or more selected from cobalt, nickel, tin, iron, and manganese. The steel cord according to claim 1 or 2, having a tensile strength of 2500 MPa or more and 4500 MPa or less. rubber and
A cord-rubber composite comprising the steel cord according to claim 1 or 2 embedded in the rubber. Bending rigidity is 0.01N or more and 0.05N or less,
Regarding the laminate in which two layers of the cord-rubber composite are laminated, the center of the long side of the laminate is fixed with the short sides located at both ends along the long side of the laminate using a fixing jig. The cord-rubber composite according to claim 4, wherein the package bending stiffness is 2N or more and 10N or less, where the package bending stiffness is defined as the reaction force when the is displaced by 0.03 mm along the short side. The cord-rubber composite according to claim 4 , comprising the steel cord so that the number of ends is 30 or more and 60 or less/50 mm. A tire comprising the steel cord according to claim 1 or 2 .

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