KR930011334B1 - Nylon 46 conjugated yarn for tire cord - Google Patents

Abstract

The fiber having a strength larger than 10.0 g/d, dry-heat shrinkage rate more than 2.0 % and elongation more than 13.0 % and composed of matrix and fibril portions, is manufactured by: composite spinning the polymer, using nylon 46 polymer, whose shole repeat unit amont the molecular chain is more than 80 mol% and relative viscosity is larger than 3.5, as a matrix component, 3- 20 % (against the whole component) of aromatic liquid crystal polyester of the intrinsic iscosity of more than 1.0 as a fibril component; drawing and heat-treating. The fiber made by the method has excellent dimensional stability and high strength.

Description

Nylon 46 Composite Fiber for Tire Cords

The present invention relates to a high-strength nylon 46 composite fiber for tire cords excellent in shape stability and a method of manufacturing the same.

Nylon fiber used in automotive tire cords has the advantage of excellent adhesion to rubber, while the strength and shrinkage rate at high temperatures drop sharply, resulting in flat spotting of the tire. . Due to these drawbacks, polyester fibers with relatively good shape stability may be used at high temperatures.

However, nylon tire cord market share is still relatively high, and if only the above-mentioned shortcomings are reinforced, it will be the most suitable material for tire cord not only for passenger cars but also for large cars such as buses and trucks.

Various high strength, low shrinkage polyamide yarns are known, and recently developed nylon 46 fibers are also used for tire cords due to their low shrinkage and heat resistance. Conventional manufacturing methods are insufficient to obtain high strength and low shrinkage (Japanese Patent Laid-Open No. 59-88492).

The nylon 46 filament yarn obtained by this method is superior in shape stability to conventional polyamides, but its strength is 8.5g / d, which is somewhat unsuitable for applications requiring high strength.

Therefore, if composite fiber is manufactured by reinforcing directional polyester fiber having excellent thermal stability and excellent mechanical properties to nylon 46 fiber, the sea component that becomes the matrix part is nylon, and thus the adhesiveness with rubber is maintained. The mechanical properties will be reinforced by a thermotropic liquid crystal polymer which is a island component forming a fibril, so that an ideal tire cord can be produced.

The present invention improves the problems of the existing nylon 46 fiber as described above, the nylon 46 composite fiber of the present invention has a strength of 10.0g / d or more, elongation 13.0% or more, dry shrinkage rate 2.0% or less (150 ℃ × 30 minutes) It is a high strength nylon 46 filament yarn with excellent form stability satisfying the requirements of.

In order to produce nylon 46 filaments satisfying the above conditions, the inventors of the present invention have a polytetramethyleneadipamide of 90 mol% or more of the total repeating units of the molecular chain, and a sulfuric acid relative viscosity (96% sulfuric acid, 1% solution, 25). ℃ 46) is a matrix component of nylon 46 polymer of 3.5 or more as a matrix component, when the composite fiber is prepared from an aromatic liquid crystal polyester having an intrinsic viscosity of 1.0 or more, 3 to 20%, It melts at 290 ~ 310 ℃ and spins at a spinning speed of 3,000m / min or more, and draws and heats it in multiple stages continuously.The strength is over 10.0g / d, elongation over 13.0%, dry heat shrinkage under 2.0% Nylon 46 filament yarn was prepared.

In detail, in the present invention, as the matrix component, a polymer having a sulfuric acid relative viscosity (96% sulfuric acid, 1% solution, 25 ° C) of 3.5 or more is used. When a polymer having a sulfuric acid relative viscosity of less than 3.5 is used, it is not preferable because the strength degradation and toughness decrease due to decomposition during the manufacturing process.

As the island component, a polymer having an intrinsic viscosity of 1.0 or more is used. If the intrinsic viscosity is lower than 1.0, it does not exhibit excellent mechanical properties.

The aromatic liquid crystalline polyester as the island component used in the present invention is described in detail in the patent application 87-12259 and the like, which the applicant has already filed.

In the present invention, in order to make the filament yarn more than 10.0g / d, when the composite spinning of nylon 46 fibers and thermotropic liquid crystal polyester, the content of island components is 3 to 20%, melted at 280 to 310 ℃ and then 3,000 It should be spun at a spinning speed of m / min or more and drawn and heat treated continuously in multiple stages.

If the content of porcelain is less than 3%, the process is difficult and sufficient strength is not obtained. When the content of the porcelain content is 20% or more, compatibility is remarkably degraded, and it is easy to cause an obstacle in the post-processing process, and it is difficult to achieve the object of the present invention.

As for the spinning temperature of this invention, 290-310 degreeC is suitable. If the temperature is lower than 290 ° C, the melting is difficult and the liquid crystal is not expressed, the strength is insufficient. If the temperature is higher than 310, decomposition occurs severely and the fiber of the present invention cannot be obtained.

The spinning speed of the present invention should be at least 3,000 m / min. If the spinning speed is 3,000 m / min or less, a shear rate is insufficient to sufficiently align the liquid crystal of the thermotropic liquid crystal polymer formed in the molten state.

If the thermotropic liquid crystal polymer is not distributed in a well-aligned form in the nylon 46 matrix portion, the strength cannot be obtained more than 10.0 g / d because it does not sufficiently serve as a reinforcing material.

When the strength is 10.0 g / d or more, the weight of the tire can be reduced, and the shape stability and high strength of the present invention can be achieved.

In the present invention, the elongation should be 13.0% or more. In the case of the complex spinning of the thermotropic liquid crystal polyester, the elongation is greatly reduced, which often causes poor operability.

In the present invention, it is possible to speed up the spinning speed and increase the molecular orientation.

In the present invention, dry heat shrinkage should be 2.0% or less (150 ° C., 30 minutes). In order to be used as a tire cord yarn, the shrinkage rate should be small at high temperatures, which is advantageous in terms of manufacturing stability and shape stability when driving a car.

In the present invention, high shrinkage, strength retention at high temperature, elasticity retention rate at the time of using the conventional nylon 6 filament yarn by composite spinning the thermotropic liquid crystal polymer as a method for producing a high strength nylon 46 filament excellent in shape stability There is an advantage to overcome the problem of low back, and achieved a shape stability and high strength compared to the conventional nylon 46 was able to develop a suitable material for the tire cord.

It will be described in more detail by the following Examples and Comparative Examples.

However, the present invention is not limited to the examples.

EXAMPLES 1-2, COMPARATIVE EXAMPLES 1-2

Addition of 15 wt% of a nylon 46 polymer having a relative viscosity of 4.0 (96% sulfuric acid and a 1% solution) and a thermotropic liquid crystalline polyester polymer having an intrinsic viscosity of 1.2, melted at 300 ° C, and has a diameter of 0.3 mm and a L / D 2.5 hole. 204 pieces were extruded into a mold.

Under the prison, a heating tube having a length of 150 mm and a temperature of 305 ° C. was installed. Under the heating tube, a relative humidity of 95% and a cooling air atmosphere of 15 ° C. were used.

Yarn was stretched and heat treated in multiple stages by high speed spinning, and the spinning speed, stretching ratio and stretching temperature are specified in [Table 1]. The discharge amount was adjusted so that the final yarn had a fineness of 1,260 deniers.

The results are shown in [Table 1].

TABLE 1

As shown in Table 1, in the present invention, it is possible to continuously stretch and heat treatment in multiple stages only when the spinning speed is 3,000 m / min or more to make the strength of nylon 46 filament yarn 10.0 g / d or more.

If the spinning speed is 3,000 m / min or less, the orientation of the thermotropic liquid crystal polyester liquid crystal deteriorates in the nylon 46 matrix, thereby making it difficult to produce high strength nylon 46 filament yarn.

[Examples 3 to 4 and Comparative Examples 3 to 4]

Only the thermotropic liquid crystal polyester content was changed, and other conditions were shown in Table 2 by spinning, stretching, and heat treatment under the same conditions as in Example 1.

TABLE 2

^* Filament yarn

As shown in Table 2, in the present invention, the physical properties were good when the amount of the thermotropic liquid crystal polymer was added in an amount of 3 to 20% by weight. .

[Examples 5-6, Comparative Examples 5-6]

Only the spinning temperature was changed and other conditions were shown in Table 3 by spinning, stretching and heat treating under the same conditions as in Example 1.

TABLE 3

As shown in Table 3, in the present invention, physical properties were good when the spinning temperature was 290 to 310 ° C. When the temperature was low as in Comparative Example 5, the formation of liquid crystal was not good, and when the temperature was high, decomposition was severe.

Claims (1)

In the nylon 46 composite fiber composed of a matrix part and a fibril part, a nylon 46 polymer having a total viscosity of 80 mol% or more and a relative viscosity of 3.5 or more is used as the matrix component. The Brill component is an aromatic liquid crystalline polyester having an intrinsic viscosity of 1.0 or more, which is 3 to 20% of the total constituents, and composite spun, followed by drawing and heat treatment, the strength of 10.0 g / d or more, dry heat shrinkage of 2.0% or more, elongation 13.0 Nylon 46 composite fiber for tire cords, characterized in that more than%.