JPH01162885A - Tire reinforced by steel cord - Google Patents

Abstract

PURPOSE: To obtain the subject tire having excellent adhesiveness to rubber and improved durability by spirally winding a steel filament on an approximately straight steel filament having nearly the same diameter as that of the former filament to give a strand and twisting the plural strands to give a reinforcing material. CONSTITUTION: The circumference of an approximately straight steel filament (a) is spirally wound with a steel filament (b) having nearly the same diameter as that of the steel filament (a) preferably in 3-20 mm twist pitch to give a strand 1. The plural strands are twisted to give a steel cord 2, which is made into a rubber compound material to give the objective tire.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a tire reinforced with steel cords, in which a plurality of strands each having one filament wound spirally around one filament are twisted together. This relates to tires reinforced with steel cord.

[Prior Art] Generally, cords used for rubber composites such as belts for radial tires for passenger cars, carcass for tires for heavy vehicles, belts, and tie bars have characteristics such as high elastic modulus, strength, dimensional stability, and adhesive properties. Although basic properties are required, steel cords, which have excellent elastic modulus and strength, are often used for these cords.

The steel cord used for the belt or carcass has a so-called layered structure, in which several strands of 3 to 5 filaments are twisted together, or a layered structure in which multiple filaments are arranged concentrically. There are some that have a so-called layered structure in which they are twisted together. For example, the twisting structure of steel cord used for the playing force of passenger car tires is the 1X5 structure shown in Figure 5 or the 6x5 structure shown in Figure 5.
There is a 1×4 structure shown in the figure.

(Problems to be Solved by the Invention) However, as shown in the figure, the cross-sectional shapes of these steel cords are the same in the longitudinal direction, and therefore voids S1 and S2 are formed in the center of the cross-section into which rubber cannot enter. Therefore, when moisture enters these gaps S1 and S2,
Moisture diffuses in the longitudinal direction of the steel cord through the gap in the center of the cross section, destroying the bond between the steel cord and the rubber and causing rust on the surface of the steel cord.

Therefore, in order to solve the above problems, a so-called open twisted steel cord was proposed in which the distance between the steel filaments was widened to make it easier for the rubber to enter the gap in the center of the cross section (Japanese Patent Laid-Open No. 55-90692 , JP-A-56-43008>.

However, the steel cords of these structures inherently have a relatively large elongation, which impairs dimensional stability, and when the composite is made into a sheet, the edges of the sheet warp, making it difficult to form tires. However, there are drawbacks that significantly impair workability.

This invention eliminates these drawbacks and provides a rubber composite with further improved adhesion to rubber, and furthermore, by using this as a reinforcing material for tires, the durability is further improved. There is a purpose in providing tires.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a strand in which one steel filament having approximately the same diameter is spirally wound around one approximately straight steel filament. The unique feature is that a plurality of these steel cords are twisted together to form a steel cord, and this is applied as a reinforcing material in the rubber of a tire.

To explain with drawings, Figure 1 is a side view of the strand, Figure 2 is a side view of the strand, and Figure 2 is a side view of the strand.
The figure is a cross-sectional view of the strand, in which a is a substantially straight steel filament, b is a steel filament having approximately the same diameter that is spirally wound around the steel filament a, and these steel filaments constitute strand 1. ing. In other words, the strand configuration is (1+
1) Xd (d=filament diameter mm). Next, twist multiple strands 1 together to create a steel cord 2.
shall be. That is, the cord 2 obtained by twisting a plurality of strands 1 can be expressed as nx (1+1)xd (n=number of strands). Therefore, for example, when n=2 as shown in FIG. 3, or when n=4 as shown in FIG.
The cord with the (1+1)Xd structure does not have voids S1 and S2 unlike conventional products, and the rubber can sufficiently penetrate into the cord due to its structure.

Furthermore, when the strands are bundled and twisted into a cord in order to prevent 1% v damage between the strands, it is desirable that the direction of twisting is the same as that of the strands. Further, the twisting pitch of the steel cord is usually in the range of 3 to 20 mm; if it is smaller than 3 mm, the strength and productivity of the cord will decrease, while if it exceeds 2 Q mm, the bending fatigue resistance and cohesiveness of the cord will decrease. Further, it is preferable to use a steel cord filament which usually has a diameter of 0.10 to 0.40 mm and is plated with brass. Here, the strands are twisted at a specific pitch, but if the strand and cord twisting pitch is made smaller, the elongation at low loads will increase, the impact from the tread surface will be alleviated, and the cushion will move.
Improves trauma resistance. However, if the twist pitch is too small, it will lead to a decrease in productivity and will also become too soft, resulting in poor handling. Therefore, it is best to twist the cord at a twist pitch that gives a load of 2 to 20 kgf at 1% elongation, preferably 3 to 10 k (If).Especially when using a cord with a low twist pitch for the outermost belt of a truck tire, it is recommended to Improves trauma resistance.

[Function] As described above, the tire using the cord of this invention is as described above, so when it is used in the belt part etc., the rubber is structurally sufficiently penetrated into the cord, so rust is prevented and damage is prevented. Even if moisture enters the tread, it will not penetrate in the axial direction of the cord and will not cause a decrease in adhesion. Moreover, since the contact surface between the rubber and the coat is larger than that of conventional products, the adhesion is further improved and the durability of the belt portion is improved.

〔Example〕

Examples 1 and 2 2x (1+1) xo, 25.3X (1+1) xo
, make 25 cords and use them for 2 layers of belt to create 1
We made a prototype of 85/70R13 tires. For the Naori residue, one piece of polyester 1500d/2 was used. Predetermined tests were conducted on this tire.

The results are shown in Table 1.

The following margins are shown in Table 1. Example 3 Next, 4x (1+1)

The carcass was made of 1500 d/24 layers of polyester. This tire was subjected to a prescribed test. The results are shown in Table 2.

Test method of Examples Air permeability: A cord was embedded in a 5 cm long rubber block, air of 2 k(]/Cm2 was sent from one end, and the flow rate was measured.

Salt water drum test Rust occurrence: Drill holes of 3 tap diameter from the inside of the tie V at 3 locations in the radial direction of the tire tread to penetrate the belt layer.

Assemble the tire to the rim and add 300cc of 10% salt water to the tire for 1.7k! Apply an internal pressure of 1]/cm2. A drum test was conducted at a speed of 50 km/h, and after driving for 30,000 km, the tire was disassembled, the belt layer was cut out, and the length of rust that occurred along the steel cord around the drill hole was measured for each cord. The average rust value divided by the total length of the steel cord is considered to be the steel cord rust occurrence degree.

Shock absorption: A Charpy type impact test was conducted, and the impact absorption energy was expressed as Comparative Example 100.

Driving test on rough road: The number of damaged parts when installed in a large dump truck and driven for 30,000 km on a test road sprinkled with crushed stones with an average of 3 crn is shown as Comparative Example 100.

Take the cord from the damaged area and divide the rust length by the total length of the cord. Percentage of tires that cannot be replaced due to belt cord damage.

As shown in the examples, it is recognized that the cord with the nx(1+1)xd structure has improved tire durability compared to the comparative example.

In particular, the improvement in trauma resistance when driving on rough roads is significant. In addition to belt parts, it can also be applied to parts that require trauma resistance and rubber penetration resistance.

〔Effect of the invention〕

As described above, the present invention is a steel filament having an n×(1+1) Since the tires are reinforced with cords, the cords have a structure that ensures a dramatic increase in the intrusion of rubber, and can be made into a rubber composite with further improved adhesion to rubber, making it extremely durable. This resulted in an excellent tire.

[Brief explanation of the drawing]

Fig. 1 is a side view of the strand according to the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is a sectional view showing a 2X (1+1) x d cord, and Fig. 4 is a 4 x (1 + 1) x d cord. 5 is a cross-sectional view showing a conventional cord with a 1×5 structure, and FIG. 6 is a cross-sectional view showing a cord with a conventional 1×4 structure. a, b... steel filament

Claims (4)

[Claims] (1) Around the almost straight steel filament,
A tire that is reinforced with steel cords made by twisting multiple strands of steel filament with approximately the same diameter into a spiral strand. (2) A tire reinforced with steel cords according to claim 1, wherein the strands and the cords are twisted in the same direction. (3) A tire reinforced with a steel cord according to claim 1 or 2, wherein the load at 1% elongation is 2 to 20 kgf. (4) A tire reinforced with a steel cord according to claim 1, 2, or 3 used in a belt.