JPS63203841A - Treatment of cord for reinforcing tire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the treatment of tire reinforcing cords made of so-called ultra-high strength nylon having a yarn strength of 12 g/d or more and a single yarn fineness of 4.5 denier or less. It is about the method.

(Prior Art) Nylon fibers have excellent strength, durability, and heat resistance among cord materials for reinforcing tires, and are therefore widely used in large tires for trucks, buses, construction, aircraft, and the like.

On the other hand, there is a strong demand for reducing the number of layers of reinforcing material in tires and reducing the number of cords inserted into the reinforcing material due to demands for cost reduction, fuel efficiency by reducing tire weight, and resource saving.

For this reason, in response to such demands, nylon fibers have recently been developed that use the same molecular weight as conventional nylon but have significantly improved strength (for example, Japanese Patent Application Laid-Open No. 70008/1983).
It is disclosed that it is possible to develop a strength of 12 g/d or more. However, such so-called ultra-high-strength nylon (hereinafter referred to as "ultra-high-strength nylon") is manufactured by applying an adhesive that is essential for bonding the cord and rubber, and then bonding at high temperatures near the cord's melting point. After the so-called dipping treatment that solidifies the agent, the strength of the cord decreases significantly.
The inventors of the present invention have discovered that there is a drawback in that the strength of the dip cord is only comparable to that of conventional nylon. Various prevention methods have been proposed for conventional high-strength nylon to eliminate the decrease in strength after dipping (JP-A-60-71238, JP-A-60-7123).
No. 9, No. 60-71240, etc.), the fact is that no method for preventing the strength reduction of such ultra-high strength nylon has yet been developed.

(Problems to be Solved by the Invention) None of the conventional methods for preventing the strength reduction of high-strength nylon can maintain the yarn strength of ultra-high-strength nylon at 12 g/d or higher, and the yarn strength of 10 g/d or higher cannot be maintained. It was related to high strength nylon of about .5 g/d.

In addition, with conventional nylon or high-strength nylon, the strength reduction rate after dipping was at most 10% or less compared to before dipping, whereas the strength reduction rate of the ultra-high strength nylon after dipping was at most 10% or less compared to before dipping. In the dipping method, the strength reached 25%, and there was a major problem in that the ultra-high strength nylon after dipping could only maintain the same strength level as conventional nylon.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for treating a tire reinforcing cord that can solve the above-mentioned problems and prevent a decrease in the strength of the cord after dipping ultra-high strength nylon.

(Means for Solving the Problems) The present inventors believe that if it is possible to prevent the decrease in strength of ultra-high strength nylon after dipping, it will be possible to significantly reduce costs, make tires lighter and more fuel efficient, and save resources, as described above. I thought it would be possible,
With the goal of preventing the strength loss of ultra-high strength nylon after dipping (approximately 25% strength loss rate), we first determined the cause of the strength loss by conducting a detailed analysis of the dip cord that had experienced strength loss.

As a result, it was discovered that the strength of the dipped cord made of ultra-high strength nylon is reduced significantly due to the special characteristics of ultra-high strength nylon, namely, the finer denier of the filaments that make up the cord. In other words, while conventional nylon filament has a denier of about 6 denier, the denier of ultra-high strength nylon filament is 2 denier, which is about 173 to 1/2 as thin.
When the cord is coated with adhesive or immersed in a dipping process using a general resorcinol-formaldehyde condensate/comb latex (hereinafter referred to as RF/LJ) mixed solution, the adhesive may contain more than 1000 strands. The dip liquid penetrates into the cord made of filament yarn, and then the cord is subjected to tension heat treatment for several tens of seconds at a high temperature near the melting point of the cord, so that the dip liquid that has penetrated inside the cord turns into resin at high temperature and prevents adhesion between the filaments. It has become clear that this causes the movement of the filaments that make up the cord to be restricted, and as a result, stress is not uniformly distributed among all the filaments that make up the cord, reducing the strength of the dip cord. In other words, most of the dip liquid that has penetrated into the cord is squeezed out of the cord in the subsequent drying process, but the slight amount of dip liquid that remains inside the cord is squeezed out after the drying process under high temperatures close to the cord's melting point. During the tension heat treatment process, it becomes resin (hardened) and restricts the movement of the filament inside the cord, resulting in a decrease in the strength of the cord.Therefore, it is important to prevent the dip liquid from soaking inside the cord. It turned out to be extremely important.

It is believed that increasing the filament denier of ultra-high-strength nylon from 2 denier to about 6 denier of conventional nylon is sufficient, but increasing ultra-high strength requires stress applied to the filament during spinning and hot drawing. This can sometimes be achieved by equalizing heat, etc., and increasing the filament's denier is undesirable because it leads to a decrease in cord strength.

In addition, even if the dipping liquid turns into resin in a conventional cord made of relatively thick filaments of about 6 denier, the movement of the filaments is not restricted much, whereas with a thin filament of 2 denier, there is a slight difference between the filaments. It has also become clear that even when a resin layer is formed, the movement of the filament is restricted, resulting in a significant decrease in the strength of the dip cord.

Therefore, the present inventors have clarified the mechanism that causes the strength reduction of ultra-high strength nylon dip cords with yarn strength of 12 g/d or more, and have developed a dip treatment method that can prevent the strength decrease of dip cords. As a result of further intensive studies to establish this, we found that when ultra-high strength nylon cords are subjected to tension heat treatment or rolling heat treatment before dipping treatment, the filaments that make up the cord are brought into a close-packed state due to heat and pressure. The present inventors have discovered that the decrease in strength of ultra-high strength nylon cords after dipping can be significantly improved by making it difficult for the dipping liquid to penetrate, leading to the completion of the present invention.

That is, the present invention provides a twisted cord made of fibers made of 6-nylon or 6.6-nylon having a single filament fineness of 4.5 denier or less and a yarn strength of 128/d or more, at a temperature of 100°C or more. The present invention relates to a method for treating a tire reinforcing cord, which comprises subjecting it to a dipping treatment after being subjected to tension heat treatment or rolling heat treatment.

In the present invention, the tension heat treatment or rolling heat treatment temperature before dipping treatment is a temperature equal to or higher than the melting point of the cord -70°C, that is, 160°C in the case of 6-nylon and 190'C or higher in the case of 6,6-nylon. It is preferable.

The reason for this is to soften the filaments and make it easier to close-pack the filaments. However, if the heat treatment temperature is too close to the melting point of the fiber, the strength of the cord will decrease, so it is preferably 210°C or lower for 6-nylon and 250°C or lower for 6.6-nylon.

In addition, the tension heat treatment or rolling heat treatment before dipping treatment is more effective as the cord tension is higher. This is because it becomes easier. The tension applied to the cord during this heat treatment is preferably within the range of 4 g/d to 16 g/d.

Furthermore, the heat treatment time is 10% from the viewpoint of heat treatment effect and productivity.
It is preferable that the time is not less than 20 seconds and not more than 20 seconds.

Furthermore, after the tension heat treatment or rolling heat treatment before the above-mentioned dipping treatment, it is preferable to continuously immerse the cord in a dip liquid without winding the cord or to apply a dip liquid to the cord, and more preferably such immersion or coating. It is preferable that the cord tension is 0.5 g/d or more when performing this.

The reason for this is that after the tension heat treatment or rolling heat treatment before the dipping treatment, the filaments that make up the cord adhere to each other, making it difficult for the dipping liquid to penetrate inside the cord. Otherwise, if the cord is dipped in this, voids will inevitably be created inside the cord, and the dipping liquid will easily penetrate into those voids.

Therefore, it is preferable to immerse the cord in the dip liquid continuously or to apply the dip liquid to the cord without winding it after the tension heat treatment or the rolling heat treatment, or to apply the dip liquid to the cord before the dipping or coating treatment with the dip liquid. In order to reduce this, it is preferable to set the cord tension to 0.5 g/d or more during the dipping treatment.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

1-5, 6 1-3 The tension heat treatment machine used in Examples 1-5 and Comparative Examples 1-3 is shown in FIG. In this machine, the cord sent out from the cord sending roll (A) is subjected to tension heat treatment in the tension heat treatment zone 1, and then the cord is wound once with the winding roll (A), as shown in Fig. 3. Tension heat treatment was performed again using a dip treatment machine.

A tension of about 1 g/d was applied to the cord between the pull rolls A-1 and B-1 shown in FIG. 1, and the temperature of the tension heat treatment zone 1 was varied as shown in Table 2 below.

The temperature and time of dry zone 2, stretch zone 3, and relaxation zone 4 shown in Figure 3 are each 130°C x 12°C.
0 seconds, 200°C x 40 seconds, 200°C x 40 seconds, and between C-1 and D-1, between D-1 and E-1, and between E-1 and F-1.
The tension between F-1 and F-1 was approximately 1.3 g/d.

In addition, in the dipping treatment step shown in FIG. 3, various nylon cords were subjected to dipping treatment using dipping liquids having the blending ratios (parts by weight) shown in Table 1 below.

】-"-1 Table Book 1 Product name: Hodogaya Chemical Atover w50 Umbrella 2 Nippon Zeon Co., Ltd. Latex This dip liquid is made by adding resorcinol-formalin condensate to 400 parts by weight of soft water with stirring, and then stirring. NaOH was then added, and after aging for 30 minutes to 1 hour, rubber latex and soft water (175.3 parts by weight) were added, and finally formalin was added while stirring. When using the dip liquid, it was aged at room temperature for 12 hours or more before use.

In Comparative Example 1 and Examples 1 to 5, a cord made of ultra-high strength 6-nylon fiber used in the present invention was used as the test cord, and in Comparative Example 2, a cord made of ultra-high strength 6-nylon fiber was used.
A cord made of high-strength 6-nylon fiber, which has started to be used as a tire cord in recent years, as described in No. 71238, No. 71239, and No. 71239 was used, and in Comparative Example 3, a cord made of high-strength 6-nylon fiber was used. I used the following code.

The results of measuring the strength and strength of these cords before and after treatment are also listed in Table 2 below.

The strength of the cord was measured by pulling it using an autograph at room temperature in accordance with JIS L1017, and determining the strength at break.

As is clear from Table 2, in Comparative Example 1, the temperature in Zone 1 shown in Figure 1 was room temperature, so the strength of the raw cord was 3.
The strength of the dip cord was 0 kg/piece, whereas the strength of the dip cord was 2
The weight was 4 kg/piece, and the strength was reduced by about 20%. On the other hand, in Examples 1 to 5, the temperature of zone 1 was set to 100
C, 130 C, 160 C, 5.180 C and 200 C, the strength of the dipped cord was improved, and the strength of the dipped cord, which could not be obtained with the high strength nylon of Comparative Example 2, could be obtained.

In addition, in Comparative Examples 2 and 3, even if the temperature in Zone 1 was raised, strength comparable to that of the raw cord was obtained. Therefore, the strength of the dip cord, which could not be obtained with conventional nylon cords, can be obtained for the first time with the present invention. It can be said that it has become.

16-10. 6 4-6 Examples 6-1
The rolling heat treatment machine used in 0 and Comparative Examples 4 to 6 was
As shown in the figure. In this machine, the cord sent out from the cord sending roll (A) is subjected to rolling heat treatment in the rolling heat treatment zone 10, and then, as in Example 1, the cord is once wound up with the winding roll (B). Tension heat treatment was performed again using the dip treatment machine shown in Figure 3.

A tension of about 1 g/d was applied to the cord between pull rolls A-2 and B-2 shown in FIG. 2, and the roll temperature in the rolling heat treatment zone 10 was varied as shown in Table 3 below.

In the subsequent treatment using the dip treatment machine shown in FIG.
The processing conditions corresponded to those of No. 5 and Comparative Examples 1 to 3. Moreover, the test cords of Examples 6 to 10 and Comparative Examples 4 to 6 were also those corresponding to Examples 1 to 5 and Comparative Examples 1 to 3, respectively.

The results of measuring the strength and strength of these cords after treatment are also listed in Table 3 below.

As is clear from Table 3, in Comparative Example 4, since the temperature in zone 10 shown in Figure 2 was room temperature, the strength of the raw cord was 30 kg/piece, whereas the strength of the dipped cord was 24.8 kg/piece. I couldn't get any relief.

On the other hand, in Examples 6 to 10, the strength of the dip cord was improved because the temperature of the zone 1o was set to 100°C, 1130°C, 1160″C, 180″C, and 200′C, respectively.

Furthermore, Comparative Examples 5 and 6 showed the same results as Comparative Examples 2 and 3 above.

11-14, 7-10 FIG. 4 shows a dipping machine that can continuously immerse the cord in a dipping liquid without winding up the cord before dipping. Examples 11-14 and Comparative Example 7-
In No. 10, the treatment was carried out using this dip treatment machine.

Pull rolls A-3, B-3, C-2, D-2, and E
-2 and F-2, and heat treatment for 40 seconds, 120 seconds, 40 seconds, and 40 seconds in tension heat treatment zone 101, drying zone 102, stretch zone 103, and relaxation zone 104, respectively. went.

still. The tension between A-3 and B-3 is approximately 0.8 g/d,
Approximately 0.1 g/d between B-3-C-2, C-2-D-2
0 between D-2-E-2 and E-2-F-2.
．． It was set to 8 g/d. Further, the same dipping liquid as in Example 1 was used.

In Examples 11 to 13 and Comparative Examples 7 to 9, drying zone 10
2 temperature to 130'C, stretch zone 103 temperature to 200°C, relax zone 104 temperature to 200''
C, and the temperature of the tension heat treatment zone 101 was varied as shown in Table 4 below.

In Example 14 and Comparative Example 10, the temperature of the drying zone 102 was 130°C, the temperature of both the stretch zone 103 and relaxation zone 104 was 230°C, 1 tension heat treatment zone 10
The temperature of No. 1 was 180°C.

In addition, as test codes, Comparative Example 7 and Examples 11 to 13
In Comparative Example 9, ultra-high strength 6-nylon was used, in comparative example 9, high strength 6-nylon was used, and in comparative example 9, ordinary 6-nylon was used.
- In Example 14, ultra-high strength 6,6-nylon was used, and in Comparative Example 10, high-strength 6,6-nylon was used.

The strength and strength measurement results of these cords before and after the above-mentioned treatment are also listed in Table 4 below.

As is clear from Table 4, in Comparative Example 7, the temperature of zone 101 was set to room temperature, so the strength of the raw cord was 30 kg/piece, whereas the strength of the dipped cord was 25.0 kg.
/ I only got zero. In contrast, Examples 11 to 13
Now let's set the temperature of zone 101 to 100℃1160"C1 respectively.
Since the temperature was set at 180°C, the strength of the dip cords tended to increase as the temperature increased, and the strength of the dip cords was significantly improved in both cases.

On the other hand, in Comparative Examples 8 and 9, the same conditions as in Example 13 were used, but the cord material was high strength 6-nylon and ordinary 6-nylon.
- Being made of nylon, the strength of the dipped cords was at most the same level as these raw cords.

In addition, in Example 14, the strength of the ultra-high strength 6.6-nylon raw cord was 29.0 kg/piece, whereas the strength of the dip cord was 28.8 kg/piece, which was almost the same strength. . On the other hand, in Comparative Example 10, the strength of the dip cord was only 25.0 kg/piece.

(Effects of the Invention) As explained above, in the processing method of the present invention, ultra-high tenacity 6-nylon or
．． It prevents the strength loss of the dipped cord, which was a problem when using 6-nylon fibers as a tire reinforcing cord, and provides a dip that could not be achieved with conventional high-strength 6-nylon or 6,6-nylon. I was able to get a powerful code.

As a result, the amount of cord used can be reduced by nearly 10 to 30%, and the effect of achieving tire weight reduction, cost reduction, resource conservation, etc. can be achieved.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the tension heat treatment process for tire reinforcing cords; Figure 2 is a schematic diagram showing the rolling heat treatment process for tire reinforcement cords; Figure 3 is a schematic diagram showing the dipping process for tire reinforcement cords. FIG. 4 is a schematic diagram showing a treatment process in which a tensioning heat treatment and a dipping treatment are continuously performed on a tire reinforcing cord. 1.101...Tension heat treatment zone 10...Rolling heat treatment zone 2.102...Drying zone 3.103...Stretch zone 4.104...Relaxation zone A-1, A-2, A- 3, B-1, B-2, B-3, C
-1゜C-2, D-1, D-2, E-1, E-2, F-
1,F-2゜G...Pull roll (A)...Cord sending roll (B)...Cord winding roll Figure 1 Figure 2 (A)

Claims (1)

[Claims] 1. Single yarn fineness is 4.5 denier or less and yarn strength is 1.
A tire reinforcing cord characterized in that a twisted cord made of fibers made of 6-nylon or 6,6-nylon having a weight of 2 g/d or more is subjected to tension heat treatment or rolling heat treatment at a temperature of 100° C. or more and then dip treatment. processing method.