KR20030024110A - Method for coating tire-stiffening bead wires and the bead wires - Google Patents

Abstract

PURPOSE: A coating method for a bead wire to reinforce a tire and the bead wire are provided to prevent oxidation on a surface of the bear wire and to improve adhesive force with a rubber by coating the surface of the bead wire with 1 to 30% in concentration of benzotriazole. CONSTITUTION: A coating method for a bead wire to reinforce a tire includes the step to coat a surface of the bead wire with benzotriazole concentration of 1 to 30%. The bead wire passes through a cotton rope when benzotriazole is absorbed. Methanol is solvent of benzotriazole by considering vaporization efficiency. Thereby, initial and aging adhesive forces with a rubber and rubber coverage are improved and oxidation of the surface of the bear wire is repressed.

Description

Coating method of bead wire for tire reinforcement and its bead wire {METHOD FOR COATING TIRE-STIFFENING BEAD WIRES AND THE BEAD WIRES}

The present invention relates to a coating method for improving the rubber adhesion of the bead wire for tire reinforcement and the bead wire, and more particularly comprising the step of coating the bead wire surface with benzotriazole solution of 1 to 30 mol% concentration The present invention relates to a bead wire coating method for a tire reinforcement, and a bead wire having excellent rubber adhesive strength coated by the method.

Bead wire is 0.3 ~ 0.5㎛ thick bronze plated on the surface of 0.95mm diameter steel wire made of carbon steel with carbon content of 0.6 ~ 0.95% .Inorganic fiber with different strength, modulus, heat resistance and fatigue resistance It is superior to organic fibers and is used in tire bead parts (see Fig. 1) for tire reinforcement.

The bead wire must maintain surface oxidation prevention from the bead wire manufacturing process to the product shipment for excellent adhesion to rubber, but it is very difficult to manage the surface oxidation below a certain level during the actual manufacturing process. Even if strict management maintains a constant surface oxidation degree, it is impossible to maintain the aging adhesive strength of the initial adhesive strength by oxidation of the surface of the plating layer due to heat, stress, and moisture over time.

Therefore, studies for preventing surface oxidation of the bead wire and improving the initial and aging adhesive strength have been conducted mainly by tire cord companies, and among them, a method of bead wire surface coating by an adhesion promoter has been intensively sought. However, no official results have been studied for bead wires. However, there have been some reports of adhesion promoter treatment techniques on steel cord surfaces. Among them, Belgian Patent No. 786,059 and German Patent No. 2,227,013, the control method for reducing the adhesion between steel cord and rubber, are representative of the mineral oil solution of organic acid and long chain aliphatic amine salt or a very small amount in this solution. A method of coating a steel cord surface with a solution of benzotriazole is proposed. However, the key point of this method is to uniformly mix the organic acid and the oil component materials contained in the solution, which is not suitable for the actual production process due to the problem that the reproducibility of the solution preparation is not guaranteed. As another example, a method of improving adhesion and surface cleanliness of steel cord and rubber by surface coating using aromatic triazole and alkylamine borate disclosed in U.S. Patent No. 147,818 of Good Year, USA In this method, the benzotriazole compound and the cyclohexylamine borate compound alone or mixed are dissolved in alcohol and then coated on the steel cord surface. This method is advantageous in that it is a simple solution manufacturing and application process, and economical and productivity is not unreasonable, but exhibits a reverse effect on the initial and aging adhesion except for maintaining the surface cleanliness due to the properties of the benzotriazole-based compound is not practical.

As a result of analyzing the prior art as described above, although many studies have been conducted to improve the initial and aging adhesion of steel cords and bead wires and rubbers, research at the laboratory level level ignoring economics and productivity has been conducted. As a result of the predominance, there is a need for a method for improving rubber adhesion by a simpler process. Furthermore, research in the bead wire sector, which has almost no formal research results, is urgently needed.

An object of the present invention is to solve the problems of the prior art as described above, it is an object of the present invention to provide a method for preventing oxidation of the surface of the bead wire and improve the adhesion to rubber.

That is, one aspect of the present invention provides a method for coating a bead wire for tire reinforcement comprising the step of coating the bead wire surface with a benzotriazole solution of 1 to 30 mol% concentration.

Another aspect of the present invention provides a bead wire for tire reinforcement coated with the above method is improved initial and aging rubber adhesion.

1 is a schematic view showing a tire structure,

FIG. 2A is a view illustrating a surface analysis result by an auger electron sepctrometer of a bead wire according to Example 5, and

FIG. 2B is a view illustrating a surface analysis result of an auger electron spectrometer of the bead wire according to Comparative Example 5. FIG.

Hereinafter, the present invention will be described in more detail.

Benzotriazole is one of the benzene-reactive compounds currently used as rust inhibitors in metal products and has the following structure:

Benzotriazole is present in the form of a white powder at room temperature, the melting point is 98.5 ℃, the boiling point is 204 ℃, it has a property of easily dissolving in water, alcohol, benzene, toluene and the like.

When the benzotriazole is coated on the bead wire surface, the present inventors can control oxidation of the bead wire surface by forming complex ions through strong ionic bonds with metal ions present on the bead wire surface. As a result, the reaction interfacial area for adhesion between the plating layer and the rubber is expanded, and the benzotriazole acts as a coupling agent between the plating layer and the rubber through such complex ion formation, and thus the rubber adhesion of the bead wire is very effective. The invention was completed.

According to the bead wire coating method of the present invention, the bead wire after the plating process, for example, bronze plating process is passed through a cotton rope sufficiently wetted with a benzotriazole solution immediately after passing through the plating bath and then uniformly coated with benzotriazole by drying. Beaded wires can be obtained.

The benzotriazole solution used in the present invention is prepared by dissolving benzotriazole at a concentration of 1 to 30 mol% in a solvent such as alcohol, benzene, toluene, acetone, ether, or water. In consideration of the solubility of benzotriazole and the degree of solvent vaporization after coating, alcohol is preferably used as the solvent, and methanol is most preferably used among alcohols.

On the other hand, if the concentration of the benzotriazole solution is less than 1 mol%, the desired rubber adhesion improving effect cannot be obtained. On the other hand, when the concentration of the benzotriazole solution exceeds 30 mol%, rubber adhesion and rubber coverage are rather reduced.

According to the present invention, no separate coating equipment is required, and the cotton rope through which the bead wire will penetrate is easily wetted with benzotriazole solution by capillary action. In addition, the bead wire once passed through the cotton rope soaked with the benzotriazole solution is naturally dried until the winding, it does not require a separate post-treatment step.

Bead wire coated with benzotriazole by the method of the present invention improves the initial and aging adhesion with rubber by about 5% or more as compared to bead wire not coated with benzotriazole, maintains stable rubber coverage, and prevents surface oxidation. do.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example 1 and Comparative Example 1 :

1 mole on each surface of 0.80 to 0.85% carbon-containing bead wire (Hyosung) of 0.95 mm in diameter plated with bronze containing 88% Cu and 12% Sn or bronze containing 97% Cu and 3% Sn A commercial tire having the composition of Table 1 below, after coating the benzotriazole methanol solution at%, 5 mol%, 10 mol%, 20 mol% and 30 mol% in air or without coating the benzotriazole methanol solution at all. Initial adhesive strength with the rubber was measured according to the ASTM D1871-84a standard and the results are shown in Table 2 below.

Example 2 and Comparative Example 2 :

1 mole on each surface of 0.80 to 0.85% carbon-containing bead wire (Hyosung) of 0.95 mm in diameter coated with bronze containing 88% Cu and 12% Sn or bronze containing 97% Cu and 3% Sn Benzotriazole methanol solution at concentrations of%, 5 mol%, 10 mol%, 20 mol% and 30 mol% in air or no benzotriazole methanol solution at all, followed by 30 ° C / relative humidity 55% environment Left for 1 week. After one week, the aging adhesive strength with the same tire rubber as used in Example 1 was measured according to ASTM D1871-84a standard and the results are shown in Table 2 below.

Example 3 and Comparative Example 3 :

1 mole on each surface of 0.80 to 0.85% carbon-containing bead wire (Hyosung) of 0.95 mm in diameter plated with bronze containing 88% Cu and 12% Sn or bronze containing 97% Cu and 3% Sn A commercial tire having the composition of Table 1 below, after coating the benzotriazole methanol solution at%, 5 mol%, 10 mol%, 20 mol% and 30 mol% in air or without coating the benzotriazole methanol solution at all. The rubber coverage was visually measured while rotating the adhesive portion between the bead wire and the rubber using a rubber for 360 ° and the results are shown in Table 2 below.

Example 4 and Comparative Example 4 :

1 mole on each surface of 0.80 to 0.85% carbon-containing bead wire (Hyosung) of 0.95 mm in diameter plated with bronze containing 88% Cu and 12% Sn or bronze containing 97% Cu and 3% Sn Benzotriazole methanol solution at concentrations of%, 5 mol%, 10 mol%, 20 mol% and 30 mol% in air or no benzotriazole methanol solution at all, followed by 30 ° C / relative humidity 55% environment Left for 1 week. One week later, using the same rubber for tires as used in Example 3, while rotating the adhesive portion between the bead wire and the rubber 360 °, the aging rubber coverage was visually measured and the results are shown in Table 2 below.

Composition of rubber for tire ingredient Parts by weight Natural rubber 100 Peptizer 0.1 Resorcinol 3 Process oil 10 Stearic acid 2 Furance black 55 Zinc oxide 10 Hexamethylene terramine 2 Antioxidant 0.75 Accelerator One Retarder 5 Sulfur 5

Benzotriazole coating Untreated process Bead Wire Type A B A B Benzotriazole solution molarity - - One% 5% 10% 20% 30% One% 5% 10% 20% 30% Adhesive force (kg / inch ² ) Comparative Example 1 79 96 Example 1 83 85 85 83 76 105 111 109 107 98 Comparative Example 2 72 109 Example 2 77 84 84 80 73 110 115 116 111 110 Coverage (%) Comparative Example 3 82 90 Example 3 82 88 88 83 79 90 95 95 95 85 Comparative Example 4 77 90 Example 4 81 81 85 77 72 90 95 93 92 85

[Remarks]

A: Sn 12%, Cu 88%

B: Sn 3%, Cu 97%

Example 5 and Comparative Example 5 :

On the surface of a 0.80 to 0.85% carbon-containing bead wire (Hyosung Co., Ltd.) of 0.95 mm in diameter coated with bronze containing 88% Cu and 12% Sn, a 5 mol% benzotriazole methanol solution was coated in air. After being left for one week in an environment of 30 ° C./55% RH, surface analysis was performed using an Auger electron spectrometer. The results are shown in FIGS. 2A and 2B (FIG. 2A: Benzotriazole Coating; FIG. 2B: Benzotriazole Uncoated).

In general, Cu and Sn are thermodynamically stable to exist as an oxide in the air, so it is natural that oxides are formed to form an oxide film on the surface of the bead wire, but as shown in FIG. 2, beads not coated with benzotriazole It was found that the wire showed a high surface oxidation degree compared to the beadwire coated with benzotriazole. These results suggest that the coating treatment with benzotriazole solution has the effect of inhibiting bead wire surface oxidation in addition to improving the rubber adhesion and rubber coverage of the bead wire.

As described in detail above, according to the present invention, bead wires with improved initial and aging rubber adhesion and rubber coverage and suppressed surface oxidation can be easily obtained.

Claims (5)

Coating method of the bead wire for tire reinforcement comprising the step of coating the bead wire surface with benzotriazole solution of 1 to 30 mol% concentration. The method of claim 1, wherein the coating step is performed by passing a bead wire immediately after plating to a cotton rope where the benzotriazole solution is sufficiently absorbed. The method of claim 1, wherein the solvent used in the benzotriazole solution is alcohol, benzene, toluene, acetone, ether or water. 4. The method for coating a bead wire for tire reinforcement according to claim 3, wherein the solvent is methanol. Bead wire for tire reinforcement coated by the method of claim 1.