JP2001207345A - Chemical fiber cord for reinforcing rubber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chemical fiber cord useful for excluding air between unvulcanized rubber materials during the vulcanization and excellent in absorptivity of the air. SOLUTION: This chemical fiber cord is obtained by twisting two kinds of filaments different in material together and one kind of the filaments has a lower melting point than a heat-treating temperature required for a bonding treatment of the other kind of the filaments.

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. Changes 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 of different materials are twisted, one of the filaments having a melting point lower than the heat treatment temperature required for bonding the other filament, for reinforcing rubber products. Chemical fiber cord.

(2) In the above (1), when the diameter of the filament having a lower melting point is Dl and the diameter of the filament having a higher melting point is Dh, the relationship of Dl ≦ Dh × 3 is satisfied. Chemical fiber cord for reinforcing rubber products.

(3) In the above (1) or (2), the total fineness of the filament having a low melting point is 10% of the fineness of the cord.
A chemical fiber cord for reinforcing rubber products, characterized in that:

(4) In the above (1), (2) or (3),
A chemical fiber cord for reinforcing rubber products, wherein the number of low melting point filaments is 10 or more.

(5) In any one of the above (1) to (4), the filament having a low melting point may be any one of polyethylene, polypropylene, 6 nylon and 6.6 nylon.
A chemical fiber cord for reinforcing rubber products, comprising a seed or two or more kinds.

(6) The chemical fiber cord for reinforcing rubber products according to any one of the above (1) to (5), wherein the cord comprises an organic fiber.

(7) In any one of the above (1) to (6), a difference between a melting point of the low melting point filament and a heat treatment temperature required for bonding the high melting point filament is 10 ° C. or more. Chemical fiber cord for reinforcing rubber products.

[0016]

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 1 is formed by twisting two types of filaments 2 and 3 made of different materials, and one having a melting point lower than the heat treatment temperature required for the bonding treatment of the other filament 3 can be applied to one filament 2. It is vital.

[0017] The bonding treatment means that when a cord is embedded in rubber as a reinforcing material for a rubber product, the cord is immersed in an adhesive solution, dried, and dried to secure adhesion between the rubber and the cord. It means a series of steps of heat treatment.

This cord 1 has one filament 2,
That is, one or more of the low-melting filaments 2 are twisted with many of the filaments 3 having a higher heat treatment temperature required for the bonding treatment, that is, the low-melting filaments 2 are scattered among the many filaments 3. It has a structure to do. Therefore, in this cord, in the heat treatment of the bonding treatment, the low melting point filament 2 is melted, and in the finally obtained rubber reinforcing cord that has been subjected to the bonding treatment,
Inside the cord, a continuous space is formed in the longitudinal direction.

Therefore, when this cord is buried 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 that 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.

Here, for the low melting point filament 2, it is preferable to select a material whose difference between its melting point and the heat treatment temperature required for the bonding treatment of the filament 3 is 10 ° C. or more. Because, considering the variation in the heat treatment temperature during the bonding treatment of the rubber product reinforcing cord, if the above temperature difference is less than 10 ° C., a part of the filament 3 may be melted and the strength of the cord may be reduced. Because there is.

Specifically, as the low melting point filament 2, polyethylene (PE), polypropylene (PP),
It is recommended to use one or more of 6 nylon and 6.6 nylon.

In the low-melting-point filament 2, the presence or absence of a twist is not particularly problematic. In short, if the low-melting-point filament 2 occupies a predetermined space and is melted during the bonding process to form a space after the bonding process. Because it is good, it is also possible to use it without applying a twist.

It is advantageous that the cord is made of an organic fiber. This is because the organic fiber is generally subjected to an adhesive treatment, and in this case, the organic fiber is heated to a temperature close to the melting point of the material of the filament 3, so that the filament 2 advantageously acts to form a melting space.
As the organic fibers, materials such as polyethylene terephthalate, polyethylene naphthalate, polyparaphenylene terephthalamide, 6 nylon, 6.6 nylon and rayon are recommended.

Next, even if the diameter of the low-melting filament 2 is much larger than the diameter of the filament 3, melting occurs during the heat treatment to form a void theoretically. 2 is filament 3
When the diameter exceeds three times the diameter of the filament 3, the filament 3 of a material having a higher melting point around the low melting point filament 2 enters this gap, and eventually an effective gap may not be formed. May not be obtained. Therefore, it is advantageous that the diameter of the low-melting filament 2 is not more than three times the diameter of the filament 3.

On the other hand, when the diameter of the low melting point filament 2 becomes smaller than the gap formed by the filaments 3,
Since the effect of the void formed by the melting of the filament 2 cannot be obtained, the diameter is preferably 90% or more of the diameter of the filament 3.

If the ratio of the total fineness of the low-melting filament 2 exceeds 10% of the fineness of the entire cord, an effective void may not be obtained as in the above case. Is 10 of the fineness of the whole cord
% Is preferable.

Further, the number of the low-melting filaments 2 is three in the example shown in FIG. 1 for convenience. However, if the total number of the cords is less than 10, sufficient voids are provided to allow air to escape during vulcanization. In some cases, 10 or more low melting point filaments 2 are mixed in the cord,
preferable.

On the other hand, the number of filaments 3 need not be particularly limited, and may be determined according to the desired performance as a rubber product reinforcing material. At this time, it is effective to disperse the staying air that the low melting point filaments 2 are uniformly dispersed and arranged in the filaments 3.

A plurality of the cords 1 shown in FIG. 1 can be twisted into a cord. That is, as shown in FIG. 2, when, for example, two of the cords 1 are twisted into a cord, the finally obtained cord is provided with a structure having a void in the low melting point filament 2 portion. The number of air intrusion diffusion paths in one cord is increased. Therefore, this cord has an advantage that the air can be more efficiently dispersed through the gap of the cord. The number of cords 1 is not limited to two, but can be increased as needed.

[0030]

EXAMPLES Comparative Example 1 Consists of 375 filaments.
Using a 1500 denier polyethylene terephthalate yarn, a twisted cord was prepared at a twist count of 40 times / 10 cm. Using two of the lower twisted cords, cords were produced with a number of twists of 40 times / 10 cm. The polyethylene terephthalate used for this code is D
uPont DSC unit, temperature rise rate 10 ° C / mi
n, the melting peak temperature (melting point) measured under the conditions of a sample weight of about 5 mg was 255 ° C. The diameter of each filament was 20 μm.

Next, this cord was immersed in an adhesive composition solution shown in Table 1, dried at 150 ° C. for 1.5 minutes, and then dried at 240 ° C.
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.

[0032]

[Table 1]

[0033]

[Table 2]

The thus obtained cord after 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. Further, a rubber sheet having the same composition and a thickness of 5 mm was attached to the upper and lower surfaces of the composite, respectively, and then 50 ml of air was injected between the rubber sheet attached to the upper side and the composite with a syringe. . Then, this sample was heated at 170 ° C. for 30 minutes, 1.96 MPa.
After sufficiently curing to room temperature, the volume of air remaining in the sample was measured. Table 4 shows the measurement results.

[0035]

[Table 3]

Invention Example 1 A 1420 denier polyethylene terephthalate yarn consisting of 355 filaments and an 80 denier polyethylene (PE) yarn consisting of 20 filaments were plied, and the number of twists was reduced to 40 times / A lower twist cord was prepared at 10 cm. Using the two lower twisted cords, cords were produced with a number of twists of 40 times / 10 cm.
The polyethylene used for this cord was DuPont.
The melting peak temperature (melting point) measured with a DSC apparatus manufactured by t under the conditions of a heating rate of 10 ° C./min and a sample weight of about 5 mg was 135 ° C. The filament diameter of both polyethylene terephthalate and polyethylene was 20 μm.

The cord thus obtained was subjected to the same adhesive 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.

Inventive Example 2 1420 denier polyethylene terephthalate yarn consisting of 355 filaments and 80 denier polypropylene (PP) consisting of 20 filaments
After the original yarns were combined, a ply-twisted cord was prepared at a ply count of 40 times / 10 cm. Then, using the two lower twisted cords, cords were manufactured with a number of twists of 40 times / 10 cm. The polypropylene used for this cord was Du
Using a Pont DSC device, the temperature was raised at a rate of 10 ° C / mi.
n, the melting peak temperature (melting point) measured under the conditions of a sample weight of about 5 mg was 165 ° C. The filament diameter of both polyethylene terephthalate and polypropylene was 20 μm. For this cord, the residual air was measured in the same manner as in Comparative Example 1 and Invention Example 1. Table 4 shows the measurement results.

Inventive Example 3 A 1420 denier polyethylene terephthalate yarn consisting of 355 filaments and an 80 denier 6 nylon yarn consisting of 20 filaments were plied, and the number of ply twists was reduced to 40 times / 10 cm. To prepare a twisted cord. Then, using the two lower twisted cords, cords were manufactured with a number of twists of 40 times / 10 cm. The nylon 6 used for this cord was manufactured by DuPont DSC
The temperature was raised at a rate of 10 ° C./min and the sample weight was
The melting peak temperature (melting point) measured under the condition of mg was 22.
5 ° C. The filament diameter of both polyethylene terephthalate and nylon 6 was 20 μm. For this cord, the residual air was measured in the same manner as in Comparative Example 1 and Invention Example 1. Table 4 shows the measurement results.

Comparative Example 2 A 1420 denier polyethylene terephthalate yarn consisting of 355 filaments and an 80 denier aramid (polyparaphenylene terephthalamide) yarn consisting of 20 filaments were twisted and then twisted. A lower-twisted cord was produced at several 40 times / 10 cm. Then, using the two lower twisted cords, the number of upper twists is 40 turns / 1.
A cord was made at 0 cm. The aramid used for this cord was measured with a DuPont DSC device at a temperature rising rate of 10 ° C./min and a sample weight of about 5 mg, but no melting peak temperature was observed. The filament diameter of both polyethylene terephthalate and aramid was 20 μm. For this cord, the residual air was measured in the same manner as in Comparative Example 1 and Invention Example 1. Table 4 shows the measurement results.

COMPARATIVE EXAMPLE 3 Using a 1260-denier 6-nylon yarn consisting of 210 filaments, a twisted cord was prepared at a twist count of 40/10 cm. And this lower twist cord 2
Using the book, a cord was prepared with a number of twists of 40 times / 10 cm. The nylon 6 used for this cord is Du
Using a Pont DSC device, the temperature was raised at a rate of 10 ° C / mi.
n, the melting peak temperature (melting point) measured under the conditions of a sample weight of about 5 mg was 225 ° C. The filament diameter was 20 μm. Then this code is given in Table 2.
After immersion in the adhesive composition shown in (1), drying at 130 ° C. for 2 minutes and heat treatment at 210 ° C. for 2 minutes to prepare an adhesive treatment code, a sample was prepared in the same manner as in Comparative Example 1, and residual air was measured. went. Table 4 shows the measurement results.

Inventive Example 4 6 nylon raw yarn of 1194 denier consisting of 199 filaments and 6 filaments consisting of 17 filaments
After twisting an 8-denier polyethylene (PE) yarn, a twisted cord was prepared at a twist count of 40 times / 10 cm. Then, using two of the lower twisted cords, the number of upper twists is 4
A cord was produced at 0 times / 10 cm. In addition, the polyethylene used for this cord was manufactured by DuPont DSC
The temperature was raised at a rate of 10 ° C./min and the sample weight was
The melting peak temperature (melting point) measured under the condition of mg was 13
5 ° C. The filament diameter of both nylon 6 and polyethylene was 20 μm. This code is also similar to Comparative Example 1 and Invention Example 1 described above.
Residual air measurements were made. Table 4 shows the measurement results.

[0043]

[Table 4]

Inventive Examples 5 to 7, Comparative Examples 4 to 6 Residual air was measured for cords prepared according to the specifications shown in Table 5 in the same manner as in Inventive Example 1 in the same manner as in Comparative Example 1 and Inventive Example 1. went. Table 5 also shows the measurement results.

[0045]

[Table 5]

[0046]

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.

FIG. 2 is a diagram showing a cross section of another cord according to the present invention.

[Explanation of symbols] 1 code 2 low melting point filament 3 filament

Claims (7)

[Claims] 1. A rubber product comprising a chemical fiber cord in which two kinds of filaments of different materials are twisted, wherein one filament has a melting point lower than a heat treatment temperature required for bonding the other filament. Chemical fiber cord for reinforcement. 2. The rubber product according to claim 1, wherein a relationship of Dl ≦ Dh × 3 is satisfied, where D1 is a diameter of a filament having a low melting point and Dh is a diameter of a filament having a higher melting point. Chemical fiber cord for reinforcement. 3. The chemical fiber cord for reinforcing rubber products according to claim 1, wherein the total fineness of the low melting point filament is 10% or less of the fineness of the cord. 4. The chemical fiber cord for reinforcing rubber products according to claim 1, wherein the number of low melting point filaments is 10 or more. 5. The method according to claim 1, wherein
A chemical fiber cord for reinforcing rubber products, characterized in that the low melting point filament is made of one or more of polyethylene, polypropylene, 6 nylon and 6.6 nylon. 6. The method according to claim 1, wherein
A chemical fiber cord for reinforcing rubber products, wherein the cord is made of organic fibers. 7. The method according to claim 1, wherein
A chemical fiber cord for reinforcing rubber products, wherein a difference between a melting point of a low melting point filament and a heat treatment temperature required for bonding a high melting point filament is 10 ° C or more.