JP5232527B2 - Manufacturing method of steel cord for reinforcing rubber articles - Google Patents

Description

  The present invention can produce a steel cord for reinforcing rubber articles by wet wire drawing, which has excellent ductility that is difficult to break, and can produce a steel cord for reinforcing rubber articles with little reduction in ductility even when a twisted wire or the like is added. Regarding the method.

  In a tire which is an example of a rubber article, a steel cord covered with rubber is applied to the belt or carcass to reinforce the tire. Such a steel cord for reinforcing rubber articles is usually manufactured by drawing a steel wire plated with brass to a desired diameter to obtain a steel filament, and twisting the steel filament in a desired number. This wire drawing process is generally performed using a slip-type multistage wire drawing machine.

  When a steel wire subjected to brass plating is wet-drawn using a slip-type multistage wire drawing machine and a wet lubricant containing an extreme-pressure additive and a surfactant, generally the extreme-pressure addition By using a zinc complex of phosphate ester or the like as the agent, friction between the die and the wire in the slip-type multi-stage wire drawing machine during wire drawing can be reduced, and damage to the die or wire can be suppressed. This ingenuity has played a huge role in increasing the productivity of steel cords. (Patent Document 1).

JP 2002-241781 A

  However, when drawing high-strength steel wires, the deformation resistance of the steel wires is high, so the heat generated during processing increases, causing problems such as deterioration of the steel wires due to age hardening and acceleration of die wear. It was easy, and the above device alone was not sufficient to solve this problem.

  For this reason, there is a demand for a method of manufacturing a steel cord for reinforcing rubber articles, which can solve such problems, by wet wire drawing, which is superior to conventional ones.

  On the other hand, zinc dialkyldithiophosphate (ZnDTP) has been widely used in lubricants such as engine oil and hydraulic fluid because it has excellent wear resistance and antioxidant properties. Until practical use.

  As a result of intensive studies to achieve the above object, the present inventor obtained a steel cord for reinforcing rubber articles superior to conventional ones by wet drawing using a wet lubricant added with ZnDTP having a specific structure. As a result, the present invention has been completed.

［式中、Ｒはそれぞれ独立して炭素数４〜１８のアルキル基である］で示されるジアルキルジチオリン酸亜鉛を含み、
前記湿式潤滑剤における、前記ジアルキルジチオリン酸亜鉛と前記界面活性剤との質量比が３：７〜４：６であることを特徴する。 That is, the method for producing a steel cord for reinforcing a rubber article according to the present invention is a method for producing a steel cord for reinforcing a rubber article obtained by twisting a plurality of filaments produced by wet drawing a brass-plated steel wire.
The wet lubricant used in the wet wire drawing is a surfactant and the following formula (I):

In the formula, R each independently is an alkyl group having 4 to 18 carbon atoms] see contains a zinc dialkyldithiophosphate represented by,
In the wet lubricant, a mass ratio of the zinc dialkyldithiophosphate to the surfactant is from 3: 7 to 4: 6 .

  In the method for producing a steel cord for reinforcing rubber articles according to the present invention, the addition amount of the zinc dialkyldithiophosphate in the wet lubricant is preferably 0.03 to 3.0% by mass.

  According to the present invention, it is possible to manufacture a steel cord for reinforcing rubber articles that has excellent ductility that is difficult to break, and that has little reduction in ductility even when processing such as stranded wire is applied.

  Below, the manufacturing method of the steel cord for rubber article reinforcement of this invention is demonstrated in detail, referring a figure. FIG. 1 is an example of a slip type multistage wire drawing machine used in the production method of the present invention.

  In the slip type multi-stage wire drawing machine 1 shown in FIG. 1, two multi-stage drive capstans 4A and 4B are arranged opposite to each other in a lubricating liquid tank 3 filled with a wet lubricant 2. In the process of alternately passing the steel wires 6 through the dies 5 to the respective stages of the drive capstans 4A and 4B, the steel wires 6 are drawn by the dies 5 at each stage. The drawn steel wire 6 is sent to the winding process from the driving capstan 8 disposed outside the lubricating liquid tank 3 through the final die 7.

  In such wet wire drawing, the method for producing a steel cord for reinforcing rubber articles of the present invention is characterized in that the wet lubricant 2 contains zinc dialkyldithiophosphate (ZnDTP) represented by the above formula (I). When wet drawing is performed using a wet lubricant containing ZnDTP having a specific structure as described above, a strong lubricating film is formed between the die 5 and the steel wire 6, so that heat generated due to the deformation resistance of the steel wire is generated. Suppressing and reducing steel cord deterioration and die wear due to age hardening. Such an effect is particularly remarkable when wet-stretching a high-strength steel wire. Here, when the carbon number of the R group in the formula (I) is less than 4 or exceeds 18, the effect of improving the ductility of the steel cord decreases. In addition, from the viewpoint of further improving the ductility of the steel cord, the carbon number of the R group in the formula (I) is preferably 6-12. The R group may be either a linear alkyl group or a branched alkyl group, but a linear alkyl group is preferred because it has a high effect of reducing friction and improving the slip property of the steel cord surface.

Wet lubrication agent used in the present invention is seen containing a surfactant by wet-drawing the steel wire using a wet lubricant with the addition of surfactant, rubber articles produced by the production method of the present invention The ductility and the like of the reinforcing steel cord can be further improved. Moreover, in order to further improve such effects obtained by adding ZnDTP to a wet lubricant, the selection of the surfactant is an important point. Examples of the surfactant used in the present invention include polyoxyethylene glycol, polyethylene glycol monoalkyl ether, polyethylene glycol dialkyl ether, polyol ester, polyether polyol, alkanolamide, and the like. Polyethylene glycol monoalkyl ether, polyethylene glycol dialkyl Ethers and polyol esters are particularly preferred.

  Moreover, it is preferable that the addition amount of the said zinc dialkyldithiophosphate (ZnDTP) in the said wet lubricant is 0.03-3.0 mass%, and it is still more preferable that it is 0.05-1.0 mass%. . If the added amount is less than 0.03% by mass, the effect of improving the ductility of the steel cord is not sufficient, and if it exceeds 3.0% by mass, the effect of improving the ductility of the steel cord does not increase, so the cost is reduced. Is not preferable.

  Furthermore, the mass ratio of the zinc dialkyldithiophosphate and the surfactant in the wet lubricant is preferably 2: 8 to 5: 5, and more preferably 3: 7 to 4: 6. Here, when the content of the zinc dialkyldithiophosphate is less than 1/4 of the content of the surfactant, the lubricating effect of the wet lubricant is not sufficient, while the content of the zinc dialkyldithiophosphate is When the content of the surfactant exceeds 1/2, the liquid stability of the wet lubricant is lowered.

  In the present invention, as long as the above conditions are satisfied for the wet lubricant, other conditions relating to the wire drawing process, such as the wire speed, the slip speed in the slip type multistage wire drawing machine, the die shape, etc. are not particularly limited. In addition, the wire drawing method of the present invention is not particularly limited as long as the steel wire is drawn by wet drawing, and any of single wire drawing and continuous wire drawing may be used.

  The steel cord for reinforcing rubber articles of the present invention is not particularly limited in its twisted structure and the like as long as the steel wire filaments obtained by the wire drawing method are twisted together.

    EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

(Examples 1 to 10, Reference Examples 1 to 10 )
The high-carbon steel wire having a diameter of about 5.5 mm is subjected to dry wire drawing repeatedly until the diameter reaches about 1.6 mm, and then the filament shown in FIG. Using the type multi-stage wire drawing machine 1, the wet lubricant 2 to which no ZnDTP is added in the comparative example is used as the wet lubricant 2, and in the examples, the following ZnDTP is included in the provisions of the present invention. Using the added wet lubricant, wire drawing was performed under various conditions shown in the table until the diameter reached about 0.20 mm. Each of the obtained steel wires was repeatedly subjected to a torsion test and indexed with the value of the comparative example being 100. The results are shown in Tables 1-4. The repeated twist test was performed by the following method. In addition, about the remainder of the described component, the lubricating liquid which consists of a normal lubricant composition was added.

(Measurement method of repeated torsion test)
The repeated twist test was performed by repeatedly applying clockwise and counterclockwise rotations to the obtained steel wire and counting the number of repetitions until cracks occurred. Further, the value of the example was indexed with the value of the comparative example as 100. The index of the repeated torsion test indicates that the higher the numerical value, the better the ductility.

  Table 1 shows the relationship between the amount of ZnDTP added to the wet lubricant and the value of the repeated twist test of the steel cord manufactured under each condition. As ZnDTP, one represented by the formula (I) and having 8 carbon atoms in the R group was used. As can be seen from Table 1, the value of the repeated torsion test is improved when the amount of ZnDTP added to the wet lubricant is 0.03% by mass or more, and is not further improved when it exceeds 3.0% by mass. Therefore, the amount of ZnDTP added to the wet lubricant is preferably 0.03 to 3.0% by mass.

Table 2 shows the relationship between the mass ratio of ZnDTP and surfactant in the wet lubricant and the value of the repeated twist test of the steel cord. As ZnDTP, 0.3% by mass of the R group having 8 carbon atoms represented by the formula (I) was added to the wet lubricant, and polyoxyethylene alkyl ether was used as the surfactant. As can be seen from Table 2, when the mass ratio of ZnDTP to the surfactant is 3: 7 to 4: 6 , the value of the repeated twist test is improved. Therefore, in the wet lubricant, the mass ratio of ZnDTP and surfactant needs to be 3: 7 to 4: 6.

  Table 3 shows the relationship between the carbon number of the R group of ZnDTP added to the wet lubricant and the value of the repeated torsion test. In addition, as ZnDTP, 0.5 mass% of the one represented by the formula (I) and R group having 8 carbon atoms is added to the wet lubricant, polyoxyethylene alkyl ether is added as a surfactant, The mass ratio of ZnDTP to the surfactant was set to 40:60. As can be seen from Table 3, when the number of carbon atoms of the R group of ZnDTP is 4 to 12, the value of the repeated twist test is improved. Accordingly, the R group of ZnDTP preferably has 4 to 12 carbon atoms.

  Table 4 shows the values of the repeated torsion test under the conditions in the table. Polyoxyethylene alkyl ether was added as a surfactant. As can be seen from Table 4, compared with Comparative Example 4 in which ZnDTP was not added to the wet lubricant, 0.5 wt% of ZnDTP represented by formula (I) and having 8 carbon atoms in the R group was added to the wet lubricant. In addition, the value of Example 20 in which the mass ratio of ZnDTP and surfactant was 40:60 was improved in the repeated twist test. Therefore, the number of carbon atoms in the R group of ZnDTP is 4 to 18, the amount of ZnDTP added to the wet lubricant is 0.03 to 3.0% by mass, and the mass ratio of ZnDTP to the surfactant is 2: 8 to 5: 5 is preferred.

It is a schematic diagram which shows a slip type multistage wire drawing machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slip type multistage wire drawing machine 2 Wet lubricant 3 Lubricating liquid tank 4A, 4B Drive capstan 5 Dies 6 Final die 7 Drive capstan

Claims (2)

In the method of manufacturing a steel cord for reinforcing rubber articles formed by twisting a plurality of filaments manufactured by wet-drawing a brass-plated steel wire,
The wet lubricant used in the wet wire drawing is a surfactant and the following formula (I):

In the formula, R each independently is an alkyl group having 4 to 18 carbon atoms] see contains a zinc dialkyldithiophosphate represented by,
A method for producing a steel cord for reinforcing rubber articles , wherein a mass ratio of the zinc dialkyldithiophosphate to the surfactant in the wet lubricant is from 3: 7 to 4: 6 .   The method for producing a steel cord for reinforcing rubber articles according to claim 1, wherein the amount of zinc dialkyldithiophosphate added in the wet lubricant is 0.03 to 3.0 mass%.

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