JP2001049545A - Chemical fiber cord for reinforcing rubber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical fiber cord excellent in air absorptivity which helps air between unvulcanized rubber materials to be removed in vulcanization. SOLUTION: This chemical fiber cord where two kinds of filaments different in diameter from each other are intertwined is formed by placing around a primarily twisted cord 2 formed by intertwined plural large diameter filaments 1 plural primarily twisted cords 4 of other kind formed by intertwining plural small diameter filaments 3 and by twisting them together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber product, and more particularly to a chemical fiber cord for reinforcing tires and industrial belts, which is manufactured by laminating a plurality of unvulcanized rubber materials.

[0002]

2. Description of the Related Art Rubber products such as industrial belts such as tires and conveyor belts often use different rubber materials for each part because the characteristics required for each part of these products are different. . Producing a rubber product from a plurality of rubber materials in this manner is also advantageous for facilitating the molding operation. For example, in the case of a tire, a tire is manufactured by laminating and molding an unvulcanized rubber material such as a carcass ply, a belt ply, a tread rubber, and a side rubber, and vulcanizing the obtained molded product.

[0003] The laminating operation of the rubber material is mainly performed by using the adhesiveness of the unvulcanized rubber. However, since the adhesiveness is strong, when the rubber material is pasted on the rubber material, it is laminated. If even a small gap remains between the materials, air is trapped in the gap, and as a result, an air pocket may be formed between the unvulcanized rubber materials. When vulcanizing such a molded body, the air between the unvulcanized rubber materials is dispersed and absorbed by the rubber under the conditions of high temperature and high pressure during vulcanization, but accumulates during the laminating operation. When the amount of air is large, a part thereof may remain in the product after vulcanization.

[0004] Air pockets remaining after vulcanization may sometimes become a concentration point of stress under mechanical input during use of the product and may become a starting point of rubber product destruction. There is.

[0005] As a countermeasure against this air pocket, a method of applying a pressing force with a roll or the like at the time of laminating the rubber material to remove air between the rubber materials, or removing a portion having an air pocket after molding or before vulcanization. There was a method of removing air by smashing it with the like.

[0006]

However, in the former method, every time a rubber material is laminated, it is necessary to apply pressure by a roll to every corner of the rubber material. This causes a change in the thickness of the rubber material, which is not preferable from the viewpoint of maintaining the dimensions of the product. On the other hand, the latter method has a problem in workability, and a hole may penetrate the product depending on the depth of the awl, which is not preferable.

[0007] The inventors of the present invention have investigated a technique for removing air trapped between unvulcanized rubber materials when manufacturing a rubber product by laminating a plurality of unvulcanized rubber materials. It has been found that it is effective to diffuse air during vulcanization through a cord embedded in rubber as a reinforcing material for the rubber product.

However, in order to eliminate air between the unvulcanized rubber materials through the cord, it is important that the cord can sufficiently absorb the air, and development of such a cord is urgently required. Accordingly, an object of the present invention is to provide a chemical fiber cord which is useful for eliminating air between unvulcanized rubber materials during vulcanization and has excellent air absorbability.

[0009]

The gist of the present invention is as follows. (1) A chemical fiber cord in which two kinds of filaments having different diameters are twisted, and a plurality of small diameter filaments are wound around a first under twisted cord in which a plurality of large diameter filaments are twisted. A chemical fiber cord for reinforcing rubber products, wherein a plurality of second under-twisted cords obtained by twisting are arranged and twisted.

(2) The chemical fiber cord for reinforcing rubber products according to (1), wherein the number of large-diameter filaments is three or more.

(3) The chemical fiber cord for reinforcing rubber products according to (1) or (2), wherein the diameter of the large-diameter filament is at least three times the diameter of the small-diameter filament.

(4) In the above (1), (2) or (3),
The total fineness of the thick filament is 20 times the fineness of the cord.
% Or less, a chemical fiber cord for reinforcing rubber products.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of a chemical fiber cord applied as a reinforcing material for a rubber product according to the present invention. The cord is obtained by twisting a plurality of small-diameter filaments 3 around a first untwisted cord 2 in which a plurality of large-diameter filaments 1, three in the illustrated example, are twisted. A plurality of twisted cords 4, two in the illustrated example, are arranged and twisted.

That is, this cord is a cord having a first ply-twisted cord 2 as a central structure. As a result, the space 5 extending in the axial direction is secured at the center of the cord.

Therefore, when this cord is embedded in rubber as a reinforcing material for a rubber product, the air that has accumulated between the unvulcanized rubber materials during the production of the rubber product is reduced by the time the rubber viscosity in the initial stage of vulcanization decreases. It penetrates into the voids in the cord and disperses in the longitudinal direction, and as the vulcanization proceeds, these dispersed air diffuses into the rubber and eventually the air pockets in the product are eliminated. Become.

If the number of the large-diameter filaments 1 is two, there is a possibility that the above-described effects cannot be obtained without securing a sufficient space in the finally formed cord. The number of 1 is preferably 3 or more.

Similarly, if the diameter of the large-diameter filament 1 is less than three times the diameter of the small-diameter filament 3, sufficient voids cannot be secured in the finally formed cord, and the above effects may not be obtained. Therefore, it is preferable that the diameter of the large-diameter filament 1 be three times or more the diameter of the small-diameter filament 3.

The total fineness of the large-diameter filament 1 is:
It is preferable that the fineness of the cord is 20% or less. If the total fineness of the large-diameter filament 1 exceeds 20% of the fineness of the finally obtained cord, the large-diameter filament tends to appear in the outermost layer of the cord, and the large-diameter filament 1
Rubber whose viscosity has been reduced in the early stage of vulcanization penetrates into the voids formed therebetween, and voids are not secured, so that it is difficult to eliminate air pockets. Here, the total fineness of the large-diameter filament 1 is the sum of the display fineness of each large-diameter filament.

The large diameter filament and the small diameter filament constituting the cord may be of the same type or different types as long as they have different diameters. Further, each of the large diameter filament and the small diameter filament may be the same or different. That is, the material of the filament does not need to be particularly limited, and may be selected in accordance with general reinforcement cords for rubber products.

[0020]

EXAMPLES Comparative Example 1 A cord was prepared using a 1667-decitex polyethylene terephthalate yarn consisting of 375 filaments, with a number of lower twists of 40/10 cm and a number of upper twists of 40 times / 10 cm. The diameter of each filament is 20μ.
m. Then, after dipping the cord in the adhesive composition liquid shown in Table 1, drying at 150 ° C. for 1.5 minutes,
For 1 minute, followed by immersion in the adhesive composition shown in Table 2, drying at 150 ° C. for 1.5 minutes, and 240 ° C.
For 2 minutes.

[0021]

[Table 1]

[0022]

[Table 2]

The thus obtained cord having been subjected to the bonding treatment is
50 on a 0.5 mm thick rubber sheet having the composition shown in Table 3.
A rubber sheet having the same thickness of 0.5 mm was placed thereon and pressure-bonded, and a composite of cord and rubber was produced. Furthermore, on top of this complex,
After a rubber sheet having the same composition and a thickness of 5 mm was attached to the lower surface, 10 ml of air was injected between the rubber sheet attached to the upper side and the composite with a syringe. The sample was vulcanized at 170 ° C. for 30 minutes at a pressure of 1.96 MPa, sufficiently cooled to room temperature, and the volume of air remaining in the sample was measured. Table 4 shows the measurement results.

[0024]

[Table 3]

Adaptation Example 1 Three large-diameter filaments (original yarns) of polyethylene terephthalate of 111 decitex are plied 40 times / 10c
m, a first ply-twisted cord was prepared. The diameter of the large-diameter filament was 100 μm. In addition, a polyethylene terephthalate 1500 dtex original yarn consisting of 338 filaments is plied 40 times / 10 cm.
Two second ply-twisted cords twisted with each other were produced. And, centering on the first produced twisted cord, the two second twisted cords are arranged around the first twisted cord,
A cord was prepared with a number of twists of 40 times / 10 cm. The cord thus obtained was subjected to the same bonding treatment as in Comparative Example 1 to prepare a sample, and the volume of residual air after vulcanization was measured. Table 4 also shows the measurement results.

Applicable Examples 2 to 4 and Comparative Examples 2 to 4 Residual air was measured for cords prepared according to the specifications shown in Table 4 in the same manner as in Compliant Example 1 in the same manner as in Comparative Example 1 and Compatible Example 1. went. Tables 4 and 5 also show the measurement results.

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

Since the cord of the present invention is excellent in air absorbency, the chemical fiber cord is used for reinforcing rubber products, so that air remaining between unvulcanized rubber materials is eliminated during vulcanization. Can provide rubber products of excellent quality.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of a cord according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 large diameter filament 2 first ply twisted cord 3 small diameter filament 4 second ply twisted cord 5 air gap

Claims (4)

[Claims] 1. A chemical fiber cord in which two kinds of filaments having different diameters are twisted, and a plurality of thin filaments are wound around a first untwisted cord in which a plurality of large diameter filaments are twisted. A chemical fiber cord for reinforcing rubber products, wherein a plurality of second under-twisted cords obtained by twisting books are arranged and twisted. 2. The chemical fiber cord for reinforcing rubber products according to claim 1, wherein the number of large-diameter filaments is three or more. 3. The chemical fiber cord for reinforcing rubber products according to claim 1, wherein the diameter of the large-diameter filament is at least three times the diameter of the small-diameter filament. 4. The chemical fiber cord for reinforcing rubber products according to claim 1, wherein the total fineness of the large-diameter filament is 20% or less of the fineness of the cord.