KR100277192B1 - Rubber reinforcing steel tire cord with excellent aging adhesiveness - Google Patents

Abstract

The present invention is a structure in which a mixture of mineral oil and ester fatty acid is coated 0.1 to 25g per 1kg of steel tire cord in order to improve adhesion between rubber and tire rubber in the rubber reinforcing steel tire cord coated with brass, wherein The mixture has a mixing ratio of mineral oil and ester fatty acid is 80:20, specific gravity is 0.860-0.865 at 20 ℃, viscosity is 20-40 cST at 40 ℃, 3-6 cST at 100 ℃, pour point 0 ~ -10 ℃ It is a technical characteristic that ester index is 35-50.

Tire cord coated with a mixture of mineral oil and ester fatty acid of the present invention, the mixture oil improves the tear properties of the rubber when the complex with the tire rubber, and the rubber component can penetrate even deep inside gap of the steel cord By inducing the rubber and the cord to have a solid structural integrity, it is expected to improve the initial bonding force and to maintain a high aging adhesive force under the severe environment of the tire driving.

Description

Rubber reinforcing steel tire cord with excellent aging adhesiveness

The present invention relates to a steel tire cord used for reinforcing rubber, and more particularly, to the surface of the brass-plated steel tire cord by applying an oil mixed with mineral oil and ester fatty acid in an appropriate ratio to prevent corrosion of the cord. The present invention relates to a steel reinforcing steel tire cord for maintaining high aging adhesion between the steel cord and tire rubber.

Steel tire cords, which are generally used to reinforce tires of a vehicle, are made of several strands in which a single wire with a brass plated surface is embedded in brass or brass plated to improve adhesion to tire rubber and freshness in the wire manufacturing process. Wires are made of cords twisted together and embedded in tire rubber.

The adhesion between the brass-plated wire and the tire rubber decreases gradually due to various factors over time compared to the initial vulcanization. Thus, the main factor causing the weakening of adhesion strength over time is the It is known for its corrosive atmospheres, including extreme heat and moisture conditions on tires.

That is, during high-speed driving of the vehicle, the temperature of the tire rises, moisture penetrates into the tire rubber, and sometimes the steel tire cord is exposed to extreme heat and moisture conditions such as being exposed to chemical decomposition and corrosive atmosphere. In this case, the initial adhesive force between the steel cord and the tire rubber drops rapidly over time.

This drop in adhesion weakens the structural integrity of the cord and tire rubber, which in turn may cause the bond between the tire rubber and the cord to separate.

Therefore, in order to extend the service life of tires reinforced by steel cords, it is required to maintain high initial adhesive force between the cord and tire rubber and to have a high aging adhesive force that can maintain the maximum initial adhesive force over time. It is becoming.

On the other hand, to date, many studies have been conducted to protect the brass cord plated tire cord and improve adhesion to rubber, and various improvements have been proposed as a result of such studies.

In the so-called twisted pair process of twisting multiple wires together in the tire cord manufacturing process, a flaw occurs on the surface of the wire by contact with various rollers and frictional contact between the wires. Such surface flaws cause rust in an oxidizing atmosphere. In order to solve this problem, benzenetricarboxylic acid ester and naphthenic acid or alkylarylsulfonic acid are disclosed in Japanese Patent Laid-Open Nos. 49-116463 and 49-117582. The method of apply | coating antirust oil containing an ester to the wire surface is disclosed, and Japanese Unexamined-Japanese-Patent No. 56-10454 discloses the film forming agent containing a rust inhibitor surfactant and a hydrocarbon.

However, the conventional steel cord surface treatment methods are focused on preventing rust on the surface of the cord, and the improvement of adhesion between the steel cord and rubber can hardly be expected, and a complicated chemical structure containing toxic chemicals is also expected. It is pointed out that the workability is poor due to the use of rust inhibitors or surfactants.

In consideration of the problems pointed out by the conventional method, Korean Patent Publication No. 2402 (Notice: 91-5667) is a process oil for rubber as a hydrocarbon-based oil as a means for rust prevention of steel cords without using harmful chemicals. , A method for applying machine oil and naphthenic oil is disclosed. Also, Korean Laid-Open Patent Publication No. 1235 (Publication No. 94-7288) applies naphthenic oil having a pour point of -50 to -70 ° C in a twisted pair process. A method is disclosed.

However, the hydrocarbon-based oil for rubber has the effect of reducing the friction of the cord surface by reducing the friction in the twisted wire process of the wire, but the effect of improving the adhesion between the steel cord and the rubber, in particular aging adhesion is very insufficient. There are disadvantages.

On the other hand, as one of the prior art related to the protection and adhesion of steel cords, Korean Patent Publication No. 4289 (Notice: 96-857) is known to improve the aging adhesive strength by coating phosphate on the wire surface . The phosphate coating method improves the aging adhesive strength by adding a small amount of phosphate to the surface of the drawn wire by phosphate in the wet lubricating oil in the process of drawing a wire with a large wire diameter to a wire with a small wire diameter using multiple dies. have.

However, the conventional method has a side effect of reducing the freshness of the wire and shortening the life of the lubricating oil by the addition of phosphate in the wet lubricating oil, even if the wire produced through the phosphate coating process, depending on the composition of the rubber There is a problem that the adhesive force does not improve at all.

Accordingly, the present invention is to solve the conventional disadvantages and problems that are pointed out in the rubber reinforcement tire steel cord, showing excellent adhesive properties for all rubber compositions, in particular rubber reinforcement tire cords significantly improved aging adhesion It is an object of the invention to provide.

According to the present invention, the rubber reinforcing tire cord coated with brass is rapidly reduced in adhesive strength with rubber under extreme heat and moisture conditions, and oil mixed with mineral oil and ester fatty acid in an appropriate ratio on the surface of the cord is used. It is based on the discovery that when applied, it shows an excellent effect on the corrosion protection of cords and the maintenance of high temperature aging adhesion.

1 is a manufacturing process diagram of an embodiment tire cord of the present invention.

Figure 2 is a manufacturing process of the tire cord according to another embodiment of the present invention.

((Description of the code for the main part of the drawing))

1. Wire 3. Twisted Pair

6,18. Oil gauze 7.19. Oil supply device

8. Tire Cord 11. Wet Lubricant

13. Middle die 14. Final die

The mixed oil which is applied to the surface of the rubber reinforcing steel tire cord of the present invention to prevent corrosion and improve the aging adhesive strength has a mixing ratio of mineral oil and ester fatty acid of about 80:20, specific gravity of 0.860-0.865 at 20 ℃. At 40 ° C., the viscosity is 20-40 cST, at 100 ° C. the viscosity is 3-6cST, and the ester index is 35-50.

In the mixed oil, the hydrocarbon composition of the mineral oil is, for example, the naphthenic and paraffinic compounds having a weight ratio of 55:45, which means that the naphthenic system has a low viscosity index and stability. It has excellent lubricity and good compatibility with synthetic rubbers such as IIR and EDPM, while paraffins are highly compatible with synthetic rubbers such as BR and SBR, and are naphthenic and paraffinic hydrocarbons. Tire cords coated with the mixture oil of the present invention comprising a mineral oil composed of a composition exhibit high compatibility with rubbers of all compositions, and such high compatibility contributes to the improvement of adhesion between the cord and the rubber, in particular aging adhesion. It seems to be.

The mixture oil used to apply the tire cord of the present invention does not need to be diluted and used at a separate concentration, and also does not need to be subjected to a drying process at a high temperature after the coating, so that the coating operation can be easily performed.

Application of the oil in the tire cord of the present invention is carried out during the cord processing process before the cord is embedded in the rubber, for example, to apply the gauze moistened with the mixed oil on the wire surface in the final drawing process of the manufacturing process of the tire cord. The method, the method of applying to each wire before the stranded wire in the stranding process, the method of applying the gauze just before winding to the reel after the stranded wire, or the method of applying the gauze just before the cord is embedded with rubber in the tire manufacturing process. will be.

The application amount range of the mixture oil applied to the surface of the tire cord shows excellent aging adhesion in a wide range, and in particular, the oil application amount for the steel cord 1 Kg is preferably maintained in the range of 0.01 to 25 g / Kg.

If the oil coating amount is less than 0.1g / Kg, the coating effect of the oil is insufficient, on the contrary, if the coating amount exceeds 25g / Kg, the coating effect of the oil tends to decrease rather than contacting the wire in the twisted pair process It is undesirable to have side effects that contaminate the guide rollers and reels.

The manufacturing process and technical characteristics of the rubber reinforcing tire cord of the present invention and various characteristics such as excellent adhesive strength will be more clearly understood by the following examples.

Example 1

Mineral oil using gauze on cord obtained by heat-treating and brass-plated 1.3mm diameter wire by wet drawing to 0.22mm diameter wire and twisting in 3 + 9x0.22 + 1 structure in stranded wire And ester fatty acid mixture was applied.

That is, as shown in FIG. 1, a plurality of wires 1 supplied from a supply reel 2 wound with a wire 1 of 0.22 mm are twisted to form the cord structure in the twisted pair device 3, and the lead capstan ( 4) Oil gauze (6) is installed on the path between the stranded device (3) and the drawing capstan (4) of the continuous process line wound by the winding reel (5) through the oil supply device (7). The oil-coated tire cord 8 was obtained by allowing continuous supply of oil.

The initial vulcanization condition was heated for 30 minutes at 150 ° C for 30 minutes at 103 atmospheres with the rubber sheet of the composition as shown in Table 1 attached to the upper and lower parts of the steel tire cord coated with oil obtained through the above process. And a complex with rubber.

The adhesion test of the rubber adhesive composite thus obtained was performed according to ASTM D-2229. In other words, the rubber adhesive composite specimens were pulled from the composite in the tensile tester and the tire cord was measured for adhesion with the rubber (initial adhesive force). Another adhesive composite specimen was tested for thermal aging adhesion under high temperature atmosphere. After the storage for 3 weeks at ℃ was measured the age-age adhesive strength in the same manner as the initial adhesive strength measurement method.

In addition, another adhesive composite was stored for 3 weeks in a 96% relative humidity of 70 ℃ to determine the water aging adhesive strength in a moisture atmosphere and then measured the adhesive strength in the same manner as the initial adhesive strength measurement method, another adhesive composite specimen In order to determine the salt aging adhesive strength in salt water was measured for 3 weeks in 20% NaCl aqueous solution and then the adhesive strength was measured by the same measurement method as the initial adhesive strength measurement method. The adhesion results of these various cases are shown in Table 2 below.

Table 1

100 parts by weight of natural rubber

Carbon black 60

Zinc Oxide 5

Stearic Acid 0.5

Sulfur 3

Benzothiazol 0.5

Aromatic Oil 1.5

Resorcinol Resin 1

TABLE 2

division Oil Coating Weight (g / Kg) Initial Adhesion (Kg) Aging Adhesion (Kg) Heat aging Water aging Salt aging Example 1 0.5 90 58 63 77 Example 2 1.2 93 71 71 80 Example 3 5.5 92 75 71 82 Example 4 10.2 95 75 72 80 Example 5 21.5 90 69 70 78 Comparative example 0.0 92 50 61 75

As can be seen from Table 2 above, in the case of the sample of the present invention, the initial adhesion is similar to that of the conventional product (comparative example), but the aging adhesiveness (thermal Aging, water aging, brine aging) is producing excellent results compared to conventional products.

Example 2

As shown in FIG. 2, the intermediate die 13 and the final die 14 in the course of passing through the chamber 12 in which the heat-treated, brass-plated 1.3 mm diameter wire 10 is filled with the wet lubricant 11. Oil on the path of the wire 17 passed through the final die 14 in the wet drawing process, which is drawn into a wire having a diameter of 0.22 mm and guided to the take-out capstan 15 and wound around the take-up reel 16. A coating agent 18 and an oil supply device 19 were installed to apply the mixture of mineral oil and ester fatty acid. In the figure, reference numeral 20 is a capstan.

The wires thus prepared were twisted into a 3 + 9x0.22 + 1 structure in a twisted pair. Preparation of the rubber adhesive composite using these cords and the adhesion test for the adhesive composite was carried out in the same manner as in Example 1, the adhesion measurement results are shown in Table 3 below.

TABLE 3

division Oil Coating Weight (g / Kg) Initial Adhesion (Kg) Aging Adhesion (Kg) Heat aging Water aging Salt aging Example 6 0.12 91 58 62 75 Example 7 1.10 92 62 62 80 Example 8 4.80 89 62 65 81 Example 9 8.20 90 66 68 81 Comparative example 0.0 92 50 61 75

As shown in Table 3, the specimens of Examples 6-9 of the present invention also had an initial adhesive force similar to that of a conventional specimen (comparative example), but the aging adhesive strength in a corrosive atmosphere including a high temperature and a moisture atmosphere was much higher than that of the conventional specimen. Able to know.

As described above, the tire cord coated with the mixture of the mineral oil and the ester fatty acid of the present invention, the mixture oil improves the tear properties of the rubber and the rubber component deep inside the steel cord when forming a complex with the tire rubber It is expected to improve the initial bonding force and to maintain the high aging adhesion under extreme conditions due to the tire driving by inducing the penetration into the gap and inducing the rubber and the cord to have a solid structural integrity.

In addition, the steel tire cord coated with the mineral oil and the ester fatty acid mixture oil of the present invention has the advantage of exhibiting high aging adhesiveness to rubber of all compositions, in addition to the tire reinforcement of various rubber products including belts, straps and hoses It can be used for reinforcement.

Claims (2)

Rubber reinforcing steel tire cord, characterized by coating a mixture of mineral oil and ester fatty acid on the surface of the steel tire cord with 0.1-25 g per 1 kg of steel tire cord to improve adhesion between rubber and tire rubber Steel tire cord for reinforcement. According to claim 1, wherein the mixture is a mixture ratio of mineral oil and ester fatty acid is 80:20, specific gravity is 0.860-0.865 at 20 ℃, viscosity is 20-40 cST at 40 ℃, 3-6 cST at 100 ℃, pour point The steel tire cord for rubber reinforcement which is 0-10 degreeC, and ester index is 35-50.