KR920008539B1 - Producing process of full aromatic polyamide fibers - Google Patents

Abstract

The method for producing wholly aromatic polyamide synthetic fiber having high strength, high viscosity and excellent spinnability comprises: solubilizing poly (P-phenylene terephthalamide) polymer with 95-100.1 % conc. sulfuric acid to make spinning solution; extruding the solution through a spinneret and air gap to coagulation bath while spraying coagulation prevention liq. to the extruding polymer via induction pipes arranged at the left and right edge of orifice. Coagulation prevention liq. is a solution which contains water or sulfuric acid less than 20 wt.%, whose temp. is higher than that of coagulation bath + 30 deg.C but lower than that of spinning solution and whose spraying speed is the same or slower than that of spinning.

Description

Manufacturing method of wholly aromatic polyamide synthetic fiber

1 is an overall schematic diagram of a spinning apparatus used in the present invention.

Figure 2 is an enlarged longitudinal sectional view of the spinneret used in the present invention.

* Explanation of symbols for the main parts of the drawings

1: Pump 2: Spinning solution transfer pipe

3: defoaming pipe 4: defoaming machine

5: stirrer 6: spinning stock solution

7: filter 8: spinning block

9: detention 10: detention inlet

11 orifice 12 induction pipe

13: filament 14: coagulation bath

15: coagulation bath 16: coagulation bath supply pipe

17: coagulation bath outlet 18: guide

19: washing device 20: drying device

21: winder 22: air layer

The present invention relates to a method for producing poly paraphenylene terephthalamide-based synthetic fibers, ie, filamentary long fibers of wholly aromatic polyamides, and more specifically, to a wholly aromatic polyamide having high strength and high elasticity and excellent spinning properties It relates to a method for producing a synthetic fiber.

In the conventional method for producing the aromatic polyamide-based long fibers, US Patent No. 4,298,565 discloses a device of a solidification bath capable of jet spinning, and in Japanese Patent Application No. 59-50763, the shape of the spin tube in the solidification bath and In terms of size, Japanese Patent Application Laid-Open No. 57-121617 introduces the jet gun and the Jet Dry-Wet Spining method, but these solidify a small amount of the radiation source at the end of the orifice at the end of detention after prolonged spinning. This has been a problem that a lot of cutting occurs during radiation is extended to the adjacent orifice.

In addition, US Patent 3,869,429, US Patent 3,869,430 also has the same problem. Therefore, the fiber obtained by the conventional method is unstable, the winding process is unstable, the productivity improvement and the wool and fibril during water washing and drying, resulting in a decrease in the fiber properties. The present invention aims to solve the conventional problems and to produce filamentary synthetic fibers of wholly aromatic polyamides having excellent physical properties of intrinsic viscosity of 4.5 or more, strength of 20 g / d or more, and initial elastic modulus of 550 g / d or more.

Hereinafter, the present invention will be described in more detail. The polyparaphenylene terephthalamide is prepared by a known method by low temperature polymerization of aromatic diamine and aromatic dieside chloride, and the sulfuric acid concentration is in the range of 95% or more and 100.1% or less. A spinning stock solution was prepared by applying heat while uniformly mixing a poly paraphenylene terephthalamide amide based polymer having an intrinsic viscosity of 5.0 or more. At this time, the content of the polymer to the solvent must be within the range of 8-21% by weight to have a spinning liquid solution in the liquid crystal, and to produce a wholly aromatic polyamide-based synthetic fiber having excellent physical properties in manufacturing the final fiber. When the liquid crystal phase spinning solution is diffusely reflected under shear force, the pearly (frosted) luster is seen, and the binding chain of the molecule can be freely stretched in the coaxial or parallel axis direction of each aromatic ring.

When the intrinsic viscosity of the polymer is 1.0 or more, it may generally exhibit liquid crystallinity, but in order to have high strength and high elasticity, the intrinsic viscosity of 5.0 or more must be prepared as a spinning solution using a polymer. The concentration range of concentrated sulfuric acid, which is a solvent of the polymer, is 95-100.1%, and it should be selected based on the intrinsic viscosity of the polymer or the concentration of the polymer dissolved in the spinning solution. When the concentration of concentrated sulfuric acid is less than 95%, the solubility of the polymer is poor, the expression of liquid crystal is difficult, and the production of a suitable spinning stock solution is hindered, so that the viscosity of the spinning stock solution is increased, and as a result, the process is difficult to be transferred or filtered. The mechanical properties of the final fiber are poor. On the contrary, when the concentration of concentrated sulfuric acid exceeds 100.1%, the amount of SO ₂ in the fuming sulfuric acid containing SO ₃ becomes excessive, which is not preferable for handling, and the partial application of the polymer occurs, which makes the spinning solution unsuitable for spinning. .

In addition, although the fiber obtained by spinning has a dense internal structure of the fiber, does not have a gloss in appearance, and the speed of sulfuric acid diffused into the coagulation bath decreases, the mechanical properties of the fiber decrease, so that the concentration of sulfuric acid as a solvent is in the range of 95-100.1%. Most preferred. In order to produce the final long fibers having excellent physical properties and spinning properties with the obtained spinning stock solution, induction pipes are installed at the left and right ends of the orifice from which the spinning stock solution is discharged, and the spinning is discharged by spraying the anti-solidification liquid through the induction pipe. The liquid was prevented from solidifying at the end of the orifice and causing the cutting. As is known, it is necessary to completely remove bubbles or impurities generated during spinning spinning solution at a constant temperature to stabilize the spinning spinning solution and to improve the physical properties of the final fiber.

The orifice diameter of the cage used in the present invention is 0.05-0.1 mm, and L / D (ratio of the length of the cage orifice / diameter of the cage orifice) is preferably 2.0-4.0. Radioactivity during spinning is strongly influenced by the stabilization of the spinning stock and the temperature of detention and spinning atmosphere. That is, the biggest cause of the loss in the conditions of the same spinning stock solution and detention is that the temperature of the atmosphere in the air layer is lowered by the influence of the coagulation bath keeping the temperature of detention at 70-80 ° C near 10 ° C.

Therefore, in the present invention, by installing an induction tube at the end of the orifice as shown in Figure 2, the water or sulfuric acid that is 30 ℃ higher than the coagulation bath temperature, maintaining the same or lower temperature than the spinning stock solution temperature emitted from the detention An aqueous solution containing 20 wt% or less was sprayed later than or equal to the spinning speed of the spinning stock solution. In this way, long-fibers with stable radioactivity, production and operation without cutting or shaking were obtained, and the morphology of the fibers was stabilized by quickly and uniformly assuring the solvent in the spinning stock solution in the coagulation bath. In addition, in order to form fibers in the air spaces at regular intervals and to obtain long fibers having excellent physical properties, the air spaces between the upper surface of the coagulation bath and the lower surface of the cell were set to 1 mm or more, preferably 3.0-15 mm.

The interval may be determined by the temperature, viscosity, concentration of the spinning stock solution, the temperature of the space atmosphere and the spinning speed (the linear speed to be wound). Deviation from the above range results in non-uniform fineness formation, dead reticulum nonuniformity and damage of orifices due to nonuniformity of the stretching point.

Next, the radiation source solution passing through the air layer is induced to the coagulation bath. At this time, the coagulation bath composition and the temperature should be controlled so that the solvent in the radiation source solution can be uniformly and rapidly diffused. In the conventional wet spinning method, the spinning rate cannot be increased because the concentration of the coagulation bath is high and the diffusion rate decreases, but the coagulation bath in the invention is adjusted to 20 wt% or less of water or sulfuric acid aqueous solution in the temperature range of 3-20 ° C. Since it is adjusted in the range of 5.5-12.0 m / sec, it was possible to obtain a wholly aromatic polyamide-based synthetic fibers having excellent physical properties of intrinsic viscosity of 4.5 or more, strength of 20 g / d or more, and initial elastic modulus of 550 g / d or more. If the coagulation bath composition and temperature are out of the above range, not only the solvent diffusion in the spinning stock solution is uneven, but also the diffusion speed is slowed, resulting in lower final fiber properties, and at the same time, the spinning speed is lowered and the radioactivity is lowered, thereby achieving the object of the present invention. There will be no.

Referring to the spinning apparatus employed in the present invention in connection with the manufacturing method of the present invention.

The solvent and the polymer are uniformly mixed to prepare a spinning stock solution, and then the pump (1) and the spinning stock feed tube (2) are transferred to the degassing machine (4), and agitated with the stirrer (5) to bubble in the spinning stock solution (6). It is completely removed by the defoaming pipe (3), filtered with a filter (7) and discharged to the detention (9) in the spinning block (8). When the radiation stock solution is discharged to the orifice 11 at the lower end of the inlet 10, the anti-solidification liquid is injected into the induction pipe 12 to form the filament 13, and in the coagulation bath 15 in the coagulation bath 14. The solvent is diffused and stretched by the linear velocity wound in the air layer 22 to form a final fiber. The height of the coagulation bath is kept constant by the coagulation bath outlet 17 and the coagulation bath supply pipe 16, and the guide 18 guides the filament in the direction of the filament to pass through the solvent washing device 19 and the drying device 20. Filamentary long fibers of the wholly aromatic polyamide, which is a final product, are obtained in the winding machine 21, and exhibit excellent materials having an intrinsic viscosity of 4.5 or more, strength of 20 g / d or more, and initial elastic modulus of 550 g / d or more. The wholly aromatic polyamide-based synthetic fibers produced by the present invention can be utilized in many fields such as automobiles, aerospace, as well as general industries, building materials, which require high strength, high modulus and wear resistance, heat resistance, and electrical insulation.

Example 1 and Comparative Example 1-5

Dissolve polyparaphenylene terephthalamide in 99.8% sulfuric acid, but dissolve the polymer content in 19.5% by weight in sulfuric acid solvent at 85 ° C for 30 minutes, remove bubbles completely, filter the foreign material, and filter the diameter of the detention orifice 0.07mm, The L / D was discharged at a spinning speed of 2.5 m / sec from the three-population, and at the same time, 70 ° C. water was injected at 1.5 m / sec into the induction pipe. At this time, the height of the air layer was maintained by 10mm to guide the coagulation bath. In the coagulation bath, 10% aqueous sulfuric acid solution was maintained at 8 ° C. and the winding speed was 9.2 m / sec, and the solvent and neutralizing salt were removed in the washing process, followed by drying to prepare a final wholly aromatic polyamide synthetic fiber. .

The results are shown in Table 1.

TABLE 1

Example 2 and Comparative Example 6-8

The same conditions as in Example 1, but different from the spraying conditions and the conditions of detention of the solidification solution showed radioactivity and physical properties.

The results are shown in Table 2.

TABLE 2

Example 3 and Comparative Example 9-11

Air layer height, coagulation bath conditions, and winding line speed were different under the same conditions as in Example 1.

The results are shown in Table 3.

TABLE 3

Claims (2)

When the spinning stock solution prepared by dissolving the poly (paraphenylene terephthalamide) polymer in 95 to 100.1% concentrated sulfuric acid is discharged from the spinneret through the air layer to the coagulation bath, it is formed through the induction tubes formed at the left and right ends of the orifice. Method for producing a wholly aromatic polyamide-based synthetic fiber characterized in that the spraying the anti-solidification liquid The anti-solidification solution is an aqueous solution containing 20% by weight or less of water or sulfuric acid, the temperature of which is a solidification bath temperature of + 30 ° C. Method for producing a wholly aromatic polyamide-based synthetic fibers, characterized in that late or equal.

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