JPH085143B2 - Metal linear body for reinforcing rubber products and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a metal linear body used as a reinforcing material for rubber products such as tires, high-pressure hoses, and conveyor belts, and particularly excellent in corrosion resistance and adhesion to rubber. Titanium metal wire having a texture of α + β phase (hereinafter referred to as α + β type titanium metal wire)
The present invention relates to a metal linear object for rubber product teaching and a method for producing the same.

In addition, the metal linear body referred to in the present invention is a generic term for a titanium wire of a single wire or a titanium cord collected by twisting a plurality of such wires, or a wire mesh, a woven fabric, a knitted fabric or the like which is a knitted product thereof. It is a thing.

[Conventional technology]

BACKGROUND ART Techniques for embedding various reinforcing materials in rubber to improve the strength and durability of rubber products have been widely practiced.
Above all, composites of rubber and metal linear objects are applied to automobile tires, high-pressure rubber hoses, conveyor belts, etc.
The required quality performance for metal linear objects for such applications is also
Although it has a wide range of properties such as strength characteristics, adhesiveness with rubber, and corrosion resistance, durability to maintain the initial quality performance is extremely important and is a universal requirement in long-term use.

However, the conventional metal linear body for reinforcing rubber products is based on a steel wire, and the surface of the metal linear body is usually plated with one of copper, zinc, brass, and bronze in order to enhance adhesion with rubber. After being subjected to the wire drawing, the wire rod is a wire rod or an aggregate or knitted wire rod for enhancing the strength by wire drawing, which causes the following problems.

[Problems to be solved by the invention]

The problem is that in a metal linear body for reinforcing rubber products based on a steel wire, the metal plating layer and the steel wire itself do not have sufficient corrosion resistance, so that there is a high temperature and high humidity environment, or water and salt exist. This means that when used for a long period of time in a corrosive atmosphere such as the environment, the steel wire is corroded, resulting in strength deterioration, breakage, etc., and the quality performance of the rubber product is significantly impaired.

In particular, automobile tires that use brass-plated steel cords as reinforcements require high quality performance in terms of high-speed durability and safety, but if the rubber on the tire surface is damaged, rainwater will penetrate inside. Or, when salt water from salt for freezing, which is seen in cold regions, infiltrate, not only the brass plating layer, but also the steel wire itself corrodes, causing a decrease in strength or breakage. There is an urgent problem that it gets noticeably worse.

On the other hand, there are stainless metal, titanium metal, etc. as a metal material having higher corrosion resistance than this steel wire. Among them, titanium metal has extremely excellent corrosion resistance, and is light and strong, so it is used for materials for marine structures and chemical plants. It is being widely used in materials, aircraft materials, etc. However, titanium metal has a problem that it cannot be used as a reinforcing material for rubber products because it has no adhesiveness with rubber.

[Means for solving problems]

In order to solve the above problems, in the present invention,
A metal product for reinforcing rubber products is composed of a titanium metal wire having an α + β phase structure and a metal plating layer of any one of copper, zinc, brass, and bronze on the surface of To secure sufficient adhesiveness.

In addition, as a method for obtaining the linear body, a surface of the α + β type titanium metal wire is plated with one kind of metal selected from the above-mentioned four kinds of metals, and then wire drawing is performed with a die or the like. Carry out. In this case, in order to improve the wire drawing workability, it is preferable to use the α + β type titanium metal wire that has been annealed in advance, or that that has undergone solution treatment and then aging treatment to further enhance the strength. Further, in order to improve the adhesion of the plating layer, the scale on the wire surface is removed after annealing.

The α + β-type titanium metal wire referred to in the present invention specifically means a titanium alloy obtained by adding a small amount of alloying elements such as aluminum, vanadium, molybdenum, and tin to titanium, for example, aluminum 6.0 wt% and vanadium 4.0%. Titanium alloy containing, or both aluminum and vanadium 6.
There is a titanium alloy containing 0% by weight and 2.0% by weight tin.

As an example of brass plating, the α + β-type titanium metal wire may be plated with brass. After the copper plating and the zinc plating are sequentially performed, the alloy may be alloyed by thermal diffusion treatment to obtain a desired plating layer. However, when the plating composition is brass,
The copper content is 55 to 75% by weight, the zinc content is 45 to 25% by weight,
On the other hand, in the case of bronze, the copper content is 80-99% by weight, the tin content is
It is desirable to set 20 to 1% by weight. If the composition is out of this range, the adhesiveness with rubber will be significantly reduced.

A titanium wire, which is one of the linear members of the present invention, is completed after a wire drawing step, and titanium cords and titanium knitted products in other forms can be made based on this.

[Action]

The plating layers of copper, zinc, brass, and bronze are all α + β
The titanium metal wire adheres firmly to the surface of the metal wire, and therefore, the adhesion of the titanium-based metal linear body to the rubber can be ensured by utilizing these plated layers.

Titanium metal shows α-type (dense hexagonal lattice) α-type at room temperature, β-phase (body-centered cubic lattice) at room temperature, β-type where α-phase precipitates by aging treatment, α- and β-phase at room temperature Mixed α +
It is well known that there is β type. The α + β type titanium metal was selected from the above because it has strength comparable to that of conventional steel wire and has good workability. A material having insufficient strength no matter how high the corrosion resistance is, is not preferable as a reinforcing material.

In addition, α + β type titanium metal wire is much more excellent in corrosion resistance than steel, and therefore, even if it is used for a long time in a corrosive atmosphere, there is no strength reduction or breakage due to corrosion, and the rubber reinforcing effect is long-term. Can last.

Furthermore, in addition to the increase in strength due to the processing after plating, the specific gravity of α + β type titanium metal is about 3/5 that of conventional steel.
Since it is extremely light, it is possible to secure high strength and at the same time reduce the weight of rubber products.

〔Example〕

Aluminum 6% by weight and titanium 4% by weight on vanadium
Using an α + β type titanium metal wire with a wire diameter of 0.6 mm
After annealing at 00 ° C for 10 minutes, the surface oxide scale was roughly removed by shot blasting, and the surface oxide scale remaining after electrolytic cleaning with a mixed aqueous solution of hydrofluoric acid and nitric acid was completely removed. Copper plating was performed in a copper pyrophosphate bath, and then zinc plating was performed in a zinc sulfate bath. Further, subsequently, thermal diffusion treatment was performed at 500 ° C. for 5 seconds to alloy the two plated layers to form a brass plated layer. At this time, metal plating was performed so that the copper content would be 63% by weight. After that, wire drawing
The titanium wire was thinned to 0.25 mm, and the obtained titanium wire was twisted with a twisting machine to produce a 1 × 5 titanium cord.

From both sides of the titanium cord thus obtained,
Rubbers having the compositions shown in the table were attached. At this time, both ends of the titanium cord were exposed to the outside of the rubber. Then, the vulcanized product at 150 ° C. for 30 minutes was used as a sample for quality performance evaluation.

Quality performance is based on initial adhesion and JIS-Z2371 35
A salt spray test using a 5% saline solution at 5 ° C. was carried out for 7 days and 1 month, and the adhesiveness, the presence or absence of rust, and the tensile strength retention rate were examined. The adhesion was evaluated by a peeling test between the titanium cord and rubber, and the rubber coverage of the titanium cord was evaluated by a 5.0-point scale. In addition, for the presence or absence of rust after the salt spray test, take out the titanium cord from the rubber, and further unravel it for 5 minutes.
After making a titanium wire, the whole surface was observed by magnifying. On the other hand, the tensile strength retention rate was obtained by performing a tensile test on the titanium cord taken out from the rubber after the salt spray test, and expressing the breaking load at this time as a ratio to the breaking load before the salt spray test.

For comparison, a conventional steel cord having a brass plating layer having a copper content of 63% by weight, and a brass plating layer manufactured by the same method as the embodiment of the present invention except that the plating step and the heat diffusion step were omitted. The same quality performance test was performed for the titanium cords that did not exist.

Table 2 shows the results of these tests. From this test result, the present invention has the same adhesiveness as the conventional product of the comparative product 1, and since no rust is found in the salt spray test, the tensile strength retention ratio is higher than that of the conventional product. It can be seen that the corrosion resistance is extremely low and the corrosion resistance is extremely excellent.

[Effect] As described above, according to the present invention, the target metal linear body is formed by adding one of metals of copper, zinc, brass, and bronze to the surface of a titanium metal wire having an α + β phase structure. Since it is composed of plated metal wire, its adhesion to rubber and corrosion resistance can be sufficiently enhanced, and its strength can also be sufficiently secured by wire drawing. Therefore, this is used as a reinforcing material. Rubber products such as automobile tires, high-pressure hoses, and conveyor belts can sufficiently withstand long-term use in a corrosive atmosphere, and have the effect of exhibiting excellent initial properties.

Claims (5)

[Claims] 1. A metal linear body for reinforcing a rubber product, which has a metal plating layer of any one of copper, zinc, brass and bronze on the surface of a titanium metal wire having an α + β phase structure. 2. The rubber product reinforcement according to claim 1, wherein the titanium metal wire having the α + β phase structure has a composition obtained by adding an alloying element such as aluminum, vanadium, molybdenum, or tin to titanium. Metal filament for use. 3. A brass plating composition having a copper content of 55 to 75% by weight and a zinc content of 45 to 25% by weight.
A metal linear body for reinforcing a rubber product according to the item. 4. The metal linear body for reinforcing a rubber product according to claim 1, wherein the plating composition of bronze has a copper content of 80 to 99% by weight and a tin content of 20 to 1% by weight. 5. A titanium metal wire having an α + β phase structure is annealed or solution treated and then aged, and the surface of the wire after the treatment is made of one of a kind selected from copper, zinc, brass and bronze. A method for producing a metal linear body for reinforcing a rubber product, which comprises forming a metal plating layer and then wire drawing.