JP2006175895A - Rubber coated steel cord and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber coated steel cord wherein high strength is attained by enhancing maximum array density by making steel cords difficult to mutually contact when used, without increasing thickness more than required thickness, and also to provide its manufacturing method. <P>SOLUTION: The steel cords 1 arrayed at prescribed intervals are coated with rubber. High strength fiber 2 is arranged between the adjacent steel cords 1 with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber-coated steel cord and a method for producing the same, and more particularly to a rubber-coated steel cord obtained by rubber-coating steel cords arranged at predetermined intervals and a method for producing the same.

  When reinforcing rubber products, reinforcing fibers (nylon, polyester, etc.) are placed in the rubber. However, in high-pressure environments and other heavy load applications such as pumping tubes and steel radial tires, steel wires A steel cord made of fine wire strands is used as a reinforcement for rubber products. In that case, a method of covering the unvulcanized rubber by restricting the arrangement of the steel cords and rubbing the rubber with a calender roll or the like while pulling it with high tension or passing it through an extrusion die is generally adopted. (For example, Patent Documents 1 to 3).

  In Patent Document 1, the thickness of the steel cord covered with rubber cannot be pressed at the portion of the steel cord, so that the thickness is thick. On the other hand, the thickness becomes thin at the portion of the rubber only, and the strength is not good. It becomes uniform and is not sufficient for use in harsh environments.

Patent Document 2 is a method of feeding a steel cord to a calender roll and coating it with rubber, and Patent Document 3 is a method of feeding it to a calender roll with a groove and coating it with rubber.
JP 2003-159909 A JP 2003-278086 A JP 7-237271 A

  However, the above prior art has a limit in increasing the density of the steel cord and producing a steel cord with higher strength. In other words, if a large number of steel cords are arranged with a narrow interval, the rubber will not spread sufficiently between the steel cords, or the arrangement will be easily disturbed and the uniformity of product quality will be disturbed. There is a problem of wear and damage.

  In order to solve this problem, it is conceivable to increase the diameter of the steel cord. In this case, however, there arises a problem that the thickness of the steel cord covered with rubber becomes too thick. For this reason, the maximum arrangement density of steel cords using steel cords with a diameter of 1 mm is limited to about 16 pieces / 25 mm.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to make it difficult for the steel cords to come into contact with each other at the time of use. It is an object of the present invention to provide an achievable rubber-coated steel cord and a method for producing the same.

  The above object can be achieved by the invention described in the claims. That is, the characteristic configuration of the rubber-coated steel cord according to the present invention is a rubber-coated steel cord in which steel cords arranged at a predetermined interval are rubber-coated, and high-strength fibers are arranged between adjacent steel cords. There is to be.

  According to this configuration, the high-strength fibers arranged between the steel cords can prevent the steel cords from contacting each other, and can surely prevent the steel cords from being worn by the contact. The number of steel cords per unit length can be increased, and the strength of the rubber-coated steel cord can be reliably increased as compared with the prior art. For example, when a steel cord having a diameter of 1 mm is used, the maximum arrangement density can be increased to about 22/25 mm by appropriately selecting the diameter of the high-strength fiber. In this case, the strength per unit length is increased. Thus, it can be improved by about 37% as compared with the prior art.

  As a result, it was possible to provide a rubber-coated steel cord capable of achieving high strength by increasing the maximum arrangement density without making the steel cords difficult to contact each other during use and without increasing the thickness more than necessary.

  It is preferable that the steel cord has a diameter of 0.7 to 1.2 mm, and the high-strength fiber is made of an aramid medium fiber having a diameter of 0.1 to 0.4 mm.

  According to this configuration, the arrangement of rubber-coated steel cords is not easily disturbed by external stress, and a rubber-coated steel cord having a small thickness and high strength can be obtained. If the diameter of the steel cord is less than 0.7 mm, when bending stress is applied at the time of molding, the arrangement is likely to be disturbed and the product strength is somewhat lowered. Conversely, if the diameter exceeds 1.2 mm, rubber coating is applied. As the thickness of the steel cord increases, the surface smoothness is disturbed. Further, when an aramid fiber is used, the adhesive strength with the rubber is further strengthened, and it is not necessary to coat with a rubber material of the same quality in advance, and the aramid fiber can be arranged as it is in the main rubber as an aramid fiber cord. If the diameter of the fiber in the aramid is less than 0.1 mm, it is difficult to prevent the abrasion between the steel cords by securing a gap between the steel cords. The steel cord cannot be rubber-coated, and the original characteristics as a rubber-coated steel cord cannot be exhibited locally.

  The characteristic configuration of the method for producing a rubber-coated steel cord according to the present invention is such that a high-strength fiber is arranged between a plurality of steel cords and is used as an extruder for extruding unvulcanized rubber. In other words, the steel cord and the high-strength fiber are rubber-coated.

  According to this configuration, there is provided a method for producing a rubber-coated steel cord that makes it difficult for the steel cords to come into contact with each other during use, and does not increase the thickness more than necessary, thereby increasing the maximum arrangement density and achieving high strength. be able to.

  It is preferable to use an aramid medium fiber having a diameter of 0.1 to 0.4 mm as the steel cord and a diameter of 0.7 to 1.2 mm as the steel cord.

  According to this configuration, since the adhesive strength with the rubber is strengthened, it is not necessary to coat with the same quality rubber material in advance, and the aramid fiber can be arranged as it is in the main rubber as an aramid fiber cord, and the manufacturing cost Can be reduced.

  It is preferable that a diameter of 0.7 to 1.2 mm is used as the steel cord and a polyethylene fiber having a diameter of 0.1 to 0.4 mm is used as the high-strength fiber.

  According to this configuration, the polyethylene fiber has a constant strength at 60 to 100 ° C. and maintains its shape, and dissolves when heated and vulcanized to about 150 ° C. Therefore, when it becomes a product, the polyethylene fiber becomes the shape of the fiber As a rubber-coated steel cord, high characteristics can be exhibited.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an apparatus for producing a rubber-coated steel cord according to the present embodiment, and FIG. 2 shows a cross-sectional structure of the topped rubber-coated steel cord.

  As shown in FIG. 2, the rubber-coated steel cord C is arranged and arranged in a row in the width direction of the rubber G, and a diameter of 0.1 mm, which is slightly smaller than the steel cord 1, is placed between the steel cords 1. The aramid fiber 2 that is a high-strength fiber of about 0.4 mm is arranged. The diameter of the steel cord 1 is preferably about 0.7 to 1.2 mm. If the diameter is less than 0.7 mm, when bending stress is applied during molding, the arrangement is likely to be disturbed and the product strength is somewhat lowered. Conversely, if the diameter exceeds 1.2 mm, the thickness of the rubber-coated steel cord increases and the surface smoothness is disturbed. From the viewpoint of production, it is desirable that the number of aramid fibers 2 and steel cords 1 is the same.

  With such a configuration, the arrangement density of the steel cords can be increased, and the steel cords 1 can be effectively prevented from contacting each other during use as a product. Rubber coated steel cord can be achieved. That is, when steel cords having a diameter of 1 mm are used in the prior art, the maximum density of the arrangement is about 16/25 mm. According to this embodiment, the arrangement density of steel cords having a diameter of 1 mm is 20 / It can be 25 mm or more.

  The aramid fiber 2 is preferably a medium fiber rather than a short fiber or a long fiber, and such an aramid fiber does not need to be coated with a rubber material of the same quality in order to reinforce the adhesive force with rubber. The aramid fiber can be placed in the main rubber as it is as an aramid fiber cord (non-dip cord).

  Here, the medium fiber is not a long fiber composed of a single elongated filament, but fibers having a medium length which is not a short fiber cut to a length of several mm to 1 mm or less are twisted together. It means a fiber that becomes a long single spun yarn such as a filament, and has a structure in which the end of the fiber protrudes from the outer peripheral surface in a fluffy shape. Specifically, Technora (trade name, manufactured by Teijin Ltd.) is preferable as such a medium fiber. When this fiber is used, it is excellent in adhesion to the rubber G, and in particular, a cobalt compound that is familiar to the steel cord is blended. Excellent adhesion to natural rubber (natural rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, or a topping rubber blended with two or more of these), and can be integrally formed without requiring a special adhesive. .

  Next, a method for manufacturing the rubber-coated steel cord C according to this embodiment will be described with reference to FIG. As shown in FIG. 1, aramid fiber 2 as a reinforcing fiber is fed from a bobbin (not shown) through a grooved roller 3 in which grooves having a constant pitch are formed. It is fed from a bobbin (not shown) and fed out through a grooved roller 4 in which grooves having a constant pitch are formed. In that case, the aramid fibers 2 and the steel cords 1 are fed out so as to be alternately arranged and fed to the extruder 6 along the guide jig 5.

  From the extruder 6, unvulcanized rubber is fed to the steel cord 1 and the reinforcing fiber 2 so as to cover the steel cord 1 and the reinforcing fiber 2. The steel cord 1 and the reinforcing fiber 2 covered with the unvulcanized rubber are sent out in a long shape via the take-up roller 7, and the rubber-coated steel cord C is manufactured. This rubber-coated steel cord C has a cross-sectional structure as shown in FIG.

  As described above, according to the present embodiment, the number of steel cords per unit length can be increased as compared with the prior art. Moreover, in order to keep the distance between the steel cords constant, the rubber is applied while applying a large tension. There is no need for coating, and a large-scale facility for applying tension is not necessary, and the facility cost can be reduced.

(Example)
Below, the manufacture example of the rubber-coated steel cord which concerns on this embodiment is demonstrated below. As shown in FIG. 3, steel cords having a diameter S of 1.12 mm (steering wires of steel wires) are arranged in the rubber G at intervals of 0.3 mm, and the diameter A is 0.2 mm between adjacent steel cords. The unvulcanized rubber is extruded with an extruder using the equipment shown in FIG. 1 so that Technora (trade name; manufactured by Teijin Ltd.), which is an aramid medium fiber, is used, and a rubber having a thickness T of about 1.9 mm A coated steel cord was produced. In this case, since the fibers in the aramid are arranged between the steel cords, the steel cords can be arranged at regular intervals without applying rubber coating while applying a large tension to the steel cords, and the arrangement density is 17.6. / 25 mm. As a result, the strength per unit length was improved by about 25% compared with the conventional arrangement density of 14 lines / 25 mm.

If the distance between steel cords with a diameter of 1.0 mm is 0.2 mm and fibers in an aramid with a diameter of 0.18 mm are arranged in the gap, an arrangement density of 20/25 mm can be achieved, and the same unit length An improvement in strength per unit was observed.
(Comparative example)
On the other hand, when a steel cord having a diameter of 1.12 mm similar to that in the above example was placed in the rubber at intervals of 0.3 mm without arranging reinforcing fibers between the steel cords, it was actually used for a pumping tube or the like. At this time, the steel cords were in contact with each other and were worn away, or the coated rubber was cracked, and could not be used.

  In order to prevent contact between steel cords having a diameter of 1.12 mm, the arrangement density must be reduced to about 14/25 mm, and the strength per unit length is about 25% compared to the example. It was low.

[Another embodiment]
(1) In the above embodiment, an example using an aramid fiber has been described. However, instead of an aramid fiber, a polyamide fiber such as nylon having a relatively low strength, a polyethylene fiber, a polyolefin fiber, or the like may be used. Good. In particular, polyethylene fiber retains a certain strength shape at 60 to 100 ° C., which covers the rubber, and dissolves at about 150 ° C., which is the vulcanization temperature. It is useful because it does not remain. In that case, the diameter of the polyethylene fiber is preferably 0.1 to 0.4 mm.
(2) As the rubber used in the present invention, various rubbers such as natural rubber and fluorine rubber can be used.

The figure explaining the manufacturing apparatus of the rubber covering steel cord concerning the present invention Cross section of the main part of the obtained rubber-coated steel cord Cross-sectional view of main parts of rubber-coated steel cord for explaining the embodiment

Explanation of symbols

1 Steel cord 2 High-strength fiber G Rubber

Claims (5)

A rubber-coated steel cord in which steel cords arranged at predetermined intervals are rubber-coated, and high-strength fibers are arranged between adjacent steel cords. The rubber-coated steel cord according to claim 1, wherein the steel cord has a diameter of 0.7 to 1.2 mm, and the high-strength fiber is made of an aramid medium fiber having a diameter of 0.1 to 0.4 mm. A rubber coating that is fed so that high-strength fibers are arranged between a plurality of steel cords, and is fed to an extruder for extruding unvulcanized rubber so that the steel cord and high-strength fibers are rubber-coated. Steel cord manufacturing method. The method for producing a rubber-coated steel cord according to claim 3, wherein a diameter of 0.7 to 1.2 mm is used as the steel cord, and an aramid medium fiber having a diameter of 0.1 to 0.4 mm is used as the high-strength fiber. The method for producing a rubber-coated steel cord according to claim 3, wherein a diameter of 0.7 to 1.2 mm is used as the steel cord, and a polyethylene fiber having a diameter of 0.1 to 0.4 mm is used as the high-strength fiber.

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