KR950013489B1 - A process for preparing an aromatic polyamide type hollow fiber - Google Patents

Abstract

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Description

Method for producing aromatic polyamide hollow fiber

1 is a cross-sectional view of an aromatic polyamide hollow fiber produced by the manufacturing method of the present invention,

2 is a longitudinal sectional view of a spinneret for producing an aromatic polyamide hollow fiber according to the production method of the present invention.

The present invention relates to a method for producing an aromatic polyamide hollow fiber, and more particularly, to a poly (paraphenylene terephthalamide) -based synthesis in which hollows are uniformly formed at a length of 10% or more substantially substantially continuously in the longitudinal direction as long fibers. It relates to a method for producing a fiber.

As a method for producing an aromatic polyamide fiber, for example, as disclosed in U.S. Patent Nos. 4,298,565, 4,070,431 and 4,048,279 and the like, poly (paraphenylene terephthalamide: PPTA) is polymerized by a known method. , While uniformly mixing with a high concentration of sulfuric acid while applying heat to prepare a spinning stock solution in solution. The spinning stock solution was spun by applying a Jet Dry-Wet Spinning system having an air layer between a normal detention and a coagulation bath to prepare a general circular fiber.

As described above, aromatic poly (paraphenylene terephthalamide) spinning stock is discharged from spinning, spinning and contacting with the coagulation bath, so that the solvent (sulfuric acid) in the spinning stock is diffused to produce a generally circular fiber. Amide fibers have been produced. On the other hand, when a spinning stock solution, such as melt spinning of nylon or polyester, passes through a slit of the spinneret, a method of manufacturing hollow fibers by blowing an external gas to the lower part of the slit has been attempted. Unlike general-purpose polymers composed of chains, aromatic polyamide-based polymers are composed of rigid polymer chains, and air is blown because the die-swelling phenomenon is very small at the time of discharge into the slit opening. Not only the hollow ratio is small, but the formed hollow is not made uniformly substantially continuously in the longitudinal direction of the long fiber, so it lacks uniformity, so that the microstructure of the fiber is peeled off or unevenly formed during spinning or post-processing. There is a problem in that the quality of the fiber is degraded, such as cracking occurs.

The present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to provide an aromatic polyamide long fiber having a hollow ratio of 10% or more in which a hollow is formed substantially and continuously uniformly in the longitudinal direction.

In order to achieve the above object, the present invention is to prepare an aromatic polyamide polymer by isotropically polymerizing aromatic diamine and aromatic dieside chloride, and then dissolving the polymer in sulfuric acid solvent to adjust the viscosity to 500 to 1,500 poise. The prepared spinning stock solution, and when the spinning stock solution is discharged and spun through a hollow mold, inert gas or coagulant is introduced into the spinning stock solution at a constant speed to make continuous hollow fibers, and then passed through a coagulation bath. A method for producing an aromatic polyamide hollow fiber, which is wound, washed with water and dried, is provided.

The present invention is described in detail as follows.

A low-molecular-weight polymerization of aromatic diamine and aromatic diesis chloride is made to produce poly (paraphenylene terephthalamide) having an intrinsic viscosity of 4.0 or more by a known method and then dissolved in sulfuric acid solvent to form a polymer spinning stock solution.

The sulfur-based solvent is selected from one of concentrated sulfuric acid, chlorosulfuric acid and fluoro sulfuric acid at a concentration of 96% to 100%. The content of the polymer relative to the solvent is preferably in the range of 12 to 21% by weight, and adjusts the viscosity of the spinning stock solution to 500 to 1,500 poise. The viscosity of the spinning stock solution is adjusted while changing the intrinsic viscosity of the polymer, the content of the polymer relative to the solvent, the temperature of the spinning stock solution, and the like.

When the liquid crystal spinning solution is diffusely reflected under shearing force, the pearlescent luster can be seen, and the binding chain of the present molecule can be freely stretched in the coaxial direction or parallel axis direction of each aromatic ring. The intrinsic viscosity of the polymer is 1 or more, and may generally indicate liquid crystallinity. However, in order to obtain the required viscosity of the spinning stock solution with high strength and high elasticity, it must be prepared as a spinning stock solution using a polymer having an intrinsic viscosity of 4.0 or more. When the polymer concentration is below the limit concentration or the solvent of the polymer deviates from the high concentration, optical isotropic or bidirectional spinning stock solution is formed, which causes the deterioration of fiber properties.

The solvent for preparing the optically anisotropic radiation stock solution may be selected from one of concentrated sulfuric acid, chloro sulfuric acid and fluoro sulfuric acid having a concentration of 96 to 100%. In this case, when the concentration of the solvent is within the above range, the solubility of the polymer is good and the optically anisotropic spinning stock solution is formed, thereby improving the liquid crystalline expression and reaching a stable viscosity state that is easy for process management. However, if the concentration of the solvent exceeds the range of 96 to 100%, the spinning stock solution is not preferable due to the excessive handling of SO ₃ in fuming sulfuric acid containing fluorine SO ₃ and the partial dissolution of the polymer. Inadequate Although the fiber obtained by spinning is not dense, the appearance is not glossiness, and the speed of sulfuric acid diffused into the coagulation solution is reduced, which lowers the mechanical properties of the fiber.

The viscosity of the spinning stock solution varies depending on the intrinsic viscosity of the polymer, the content of the polymer with respect to the solvent, the type and concentration of the solvent, the temperature of the spinning stock solution, and the like, and depends particularly on the content of the polymer and the concentration of the solvent. As the polymer content increases, the viscosity rises sharply and then falls below the limit concentration, rapidly drawing the same shape. When the final saturation concentration is reached, the viscosity rises exponentially and solidifies. Therefore, an anisotropic spinning solution capable of expressing liquid crystals can be obtained only when the content of the polymer in the solvent is in the range of 12 to 21% by weight, and the concentration of the spinning solution required to form a continuous and uniform hollow in the longitudinal direction of the long fibers. Viscosity can be obtained.

According to the present invention, by adjusting the above-mentioned parameters, the viscosity of the spinning stock solution is adjusted within the range of 500 to 1,500 poise in order to uniformly form the hollow ratio in the longitudinal direction by 10% or more. If the viscosity is out of this range, the hollowness at the time of hollow formation is lacking and the hollow ratio is lowered.

The spinning stock solution, which has a viscosity adjusted within the range of 500 to 1,500 poise, is then discharged through a hollow spinneret as shown in FIG. 2, wherein the inert gas or coagulant fluid is discharged from the end of the hollow spinneret. Blowing at a constant speed into the inside of the spinning stock solution to produce a continuous hollow fiber.

The rate of introduction and discharge of inert gas or coagulant into the spinneret to be blown into the spinning stock solution for hollow formation should not be faster than that of the spinning stock solution. An inert gas is a gas which does not cause a decrease in physical properties or quality of the radiation stock solution by reaction or oxidation when it is blown into the spinning stock solution to form a hollow, and for example, nitrogen may be used. As the coagulating solution, a liquid used in a Jet Dry-Wet Spinning system, that is, an aqueous solution of sulfuric acid, which is water or a polymer solvent.

After the hollow is formed through the spinneret, the hollow fiber passed through the coagulation bath is washed and dried in a conventional manner. It is preferable that the winding speed of the hollow fiber in which the hollow is formed is 2 to 6 times the spinning spinning speed discharged from the cap.

If the winding speed of the hollow fiber is less than 2 times the ejection speed of spinning stock solution, the orientation of the molecular chain is insufficient, and the physical properties of the fiber are lowered. When the hollow fiber is more than 6 times, the formation of the hollow fiber becomes difficult due to the abnormality of the hollow fiber formation rate, which leads to difficulty or destruction of the hollow fiber. Continuous winding becomes difficult.

As described above, the most important factors in producing the aromatic polyamide-based hollow fiber are the viscosity of the spinning solution and the form of the hollow sphere, the method of blowing the inert gas or the coagulating solution into the spinning solution, and the relationship between the discharge rate and the winding speed. Determined by

The hollow fiber prepared according to the method of the present invention is an aromatic polyamide long fiber having a hollow ratio of 10% or more and possesses excellent mechanical properties of strength of 18 g / d or more and elasticity of 550 g / d or more. In addition, the hollow fiber is high in bulkiness and low in weight, and the heat insulation effect is high due to the excellent heat resistance characteristic of the aramid fiber is expected to expand its use.

Therefore, the aromatic polyamide-based hollow fiber manufactured according to the present invention can be utilized in many fields such as automobile, aerospace, general industry, building materials, etc., where high strength, high modulus and wear resistance, heat resistance, and electrical insulation are required.

Below, the preferable Example and the comparative example of this invention are described. However, these examples are merely provided to more easily understand the present invention, the present invention is not limited to these examples.

Example 1

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 6.5, prepared by isothermally polymerizing 1,4-phenylenediamine and terephthaloyl chloride in 99.9% sulfuric acid and the polymer content of sulfuric acid as 19.8% by weight The solution was dissolved while warming to prepare an anisotropic spinning solution having a viscosity of 1,400 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 100 m / min, and a coagulation bath is introduced into the spinning stock solution at a speed of 80 m / min and spun at a string portion inside the cap. After passing through the air layer, the coagulation bath was passed to prepare a hollow fiber. The coagulation bath was used for 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 40 m / min, washed with water and dried.

Example 2

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 5.5, prepared by isothermally polymerizing 1,4-phenylenediamine and terephthaloyl chloride in 99.9% sulfuric acid, and a polymer content of sulfuric acid was 21% by weight. The solution was dissolved while warming to prepare an anisotropic spinning solution having a viscosity of 1,000 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 90m / min, and nitrogen is injected into the spinning stock solution at a speed of 90m / min and spun at the end of the inside of the cap. After coarse, passed through a coagulation bath to form a hollow fiber. The coagulation bath was used 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 30 m / min, washed with water and dried.

Example 3

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 5.0, prepared by isothermally polymerizing 1.4-phenylenediamine and terephthaloyl chloride in 99.9% sulfuric acid and warmed with 13% by weight of a polymer content of sulfuric acid. The solution was dissolved to prepare an anisotropic spinning solution having a viscosity of 600 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 70m / min, and nitrogen is injected into the spinning stock solution at a speed of 60m / min and spun at the end of the inside of the cap. After coarse, passed through a coagulation bath to form a hollow fiber. The coagulation bath was used for 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 500 m / min, washed with water and dried.

Comparative Example 1

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 4.5, prepared by isothermally polymerizing 1,4-phenylenediamine and terephthaloyl chloride at 99.9% sulfuric acid, and the polymer content of sulfuric acid was 11% by weight. The solution was dissolved while warming to prepare an anisotropic spinning solution having a viscosity of 450 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 100m / min, and the nitrogen is introduced into the spinning stock solution at a speed of 100m / min and spun at the end of the inside of the cap. After coarse, passed through a coagulation bath to form a hollow fiber. The coagulation bath was used for 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 450 m / min, washed with water and dried.

Comparative Example 2

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 6.5, prepared by isothermally polymerizing 1,4-phenylenediamine and terephthaloyl chloride in 99.9% sulfuric acid and the polymer content of sulfuric acid as 23% by weight It was dissolved while warming to prepare an anisotropic spinning solution having a viscosity of 1,600 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 70m / min, and nitrogen is injected into the spinning stock solution at a speed of 100m / min at the end of the inside of the cap, and the air layer is discharged. After coarse, passed through a coagulation bath to form a hollow fiber. The coagulation bath was used for 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 350 m / min, washed with water and dried.

Comparative Example 3

A poly (paraphenylene terephthalamide) polymer having an intrinsic viscosity of 5.5, prepared by isothermally polymerizing 1,4-phenylenediamine and terephthaloyl chloride in 99.9% sulfuric acid, and the polymer content of sulfuric acid was 19.8% by weight. The solution was dissolved while warming to prepare an anisotropic spinning solution having a viscosity of 1,200 poise.

Next, the spinning stock solution is supplied into the hollow spinneret and discharged and spun at a speed of 150m / min, and the nitrogen is introduced into the spinning stock solution at a speed of 150m / min and spun at the end of the inside of the cap. After coarse, passed through a coagulation bath to form a hollow fiber. The coagulation bath was used for 10% by weight aqueous sulfuric acid solution and maintained at 7 ℃ temperature.

The hollow fiber passed through the coagulation bath was wound at a winding speed of 1,000 m / min, washed with water and dried.

The physical properties of the polyamide hollow fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 1 below.

TABLE 1

Claims (8)

The aromatic polyamide polymer was prepared by isotropically polymerizing the aromatic diamine and the aromatic dieside chloride in an equimolar amount, and then dissolving the polymer in a sulfuric acid solvent to prepare a spinning stock solution having a viscosity adjusted to 500 to 1,500 poise, and the spinning stock solution was hollowed out. Aromatic polyamide consisting of inert gas or coagulant liquid flowing into the spinning stock solution at a constant rate when discharged and spun through the metal mold to make continuous hollow fibers, passing through a coagulation bath, winding up, washing and drying Method of producing hollow fibers. The method of claim 1 wherein the aromatic polyamide polymer is a poly (paraphenylene terephthalamide) having an intrinsic viscosity of at least 4.0. The method of claim 1, wherein the sulfuric acid solvent is concentrated sulfuric acid, chloro sulfuric acid or pulluro sulfuric acid in a concentration of 96% to 10%. The method of claim 1, wherein the content of the polymer relative to the sulfuric acid solvent is 12 to 21% by weight. The method of claim 1, wherein the inflow rate of the inert gas or coagulant into the hollow spinneret is not faster than the discharge rate of the spinning stock solution. The method of claim 1 wherein the coagulation solution is water or aqueous sulfuric acid solution. The method of claim 1 wherein the insoluble gas is nitrogen. The method of claim 1, wherein the winding speed of the hollow fiber is in the range of 2 to 6 times the discharge speed of the spinning stock solution spun from the spinneret.