KR900003334B1 - Aromatic polyamide pulp type single fiber and that's process of manufacutre - Google Patents

Abstract

Aromatic polyamide pulp-type single fiber is prepd. by: preparing an optical anisotropic liquid crystal prepolymer having 1.0-4.0 inherent viscosity before polymn. terminating by adding equiv. mol. pts. of aromatic diamine and aromatic diacidchloride in amide based solvent insolving 0.5-15 wt.% inorg salt; extrusionspraying the prepolmer through a spinning nozzle at below 50≰C with the soln. of t-amine or the mixt. soln of the t-amine and amide together with polymn. accelerating agent; making the final fiber not contg. crystalline- defect layer by above 50 sec-1 shear stress. The prepolymer has the repeat unit of formula (I) or (II). In formulas, R1, R2, R3=(II)-(XI) are different or same; X=H, Cl or Br.

Description

Aromatic Polyamide Pulp Upper Fiber and Manufacturing Method Thereof

1 is a schematic diagram illustrating a manufacturing process of the apparatus for manufacturing polyamide pulp upper fiber according to the present invention.

2 is an enlarged cross-sectional view of the nozzle jet apparatus of FIG.

3A and 3B are enlarged cross-sectional views of the nozzle of FIG. 2.

Figure 4a is a photograph taken by enlarging the cross section of the polyamide pulp upper fiber according to the present invention with an electron microscope.

4b is a photograph taken by enlarging a cross section of a fibrous phase by simple extrusion with an electron microscope.

* Explanation of symbols for the main parts of the drawings

1: reactor 2: reservoir

3: feed line 4: gear pump

5: circulation pump 6: feed line

7: nozzle jet 8: ejection pipe

9: recovery tank

The present invention relates to an aromatic polyamide pulp upper fiber and a method for manufacturing the same. More specifically, after preparing a liquid crystal prepolymer of an aromatic polyamide, the prepolymer and the polymerization accelerator are injected by molecular orientation polymerization. The present invention relates to an aromatic polyamide pulp upper fiber and a method for producing the same, which have no crystal defect layer in the molecular chain of the final product and are excellent in strength.

In general, aromatic polyamide fibers, also known as aramid fibers, are fibers composed of wholly aromatic polymers in which molecular chains are formed by main bonds of amide groups. In particular, in the case of para-orientation, they have high strength and high modulus as well as chemical and mechanical stability. And it has the advantage of excellent heat resistance, such aramid fibers are used in many industrial fields, especially as a reinforcing fiber of a high strength lightweight composite material.

Para-oriented aramid fibers having the characteristics described above can be prepared by wet spinning using a dope of photonic anisotropic carboxyaromatic polyamide, as published by Kwolek of the Federal Republic of Germany. The para-oriented aramid fibers thus produced have excellent strength and can further improve their tensile strength and elasticity by heat treatment under tension.

Since then, a number of techniques for the production of para-oriented aramid fibers have been steadily published. For example, US Pat. Although it is described that high-strength fibers are formed through the stretching process, this method requires an additional process such as the manufacture of yellow-doped dope, and has a crystal defect layer inside the fiber structure when the fiber is manufactured by using sulfuric acid. It was not desirable.

In addition, the manufacturing method of the aromatic polyamide expanded upper fiber described in Japanese Unexamined Patent Publication No. 59-47,694 is a method of preparing by stirring and precipitation of a polymer solution dissolved in an amide organic solvent, in which case it must be a low molecular weight polymer to dissolve it in an organic solvent. In addition, it is possible to improve the degree of polymerization due to stirring and precipitation in a solvent such as water or alcohol.

On the other hand, the other techniques to improve the defects are U.S. Patent No. 4,511,623 and Japanese Patent Application No. 57-10,885 as examples, but according to these techniques due to the rapid increase in the reaction rate by the simple molecular orientation method Not only was it impossible to manage, there was a drawback of having a crystal defect layer inside the fiber by simply extruding a 300-poise initial polymerization solution into a tertiary amine.

와 같은 이온성의 사슬말단부(ionic molecularchain end)가 생성되고, 이 부분이 섬유형성시 군(cluster)을 형성하게 되어 결정의 마디부분이 되고 섬유축에 수직으로 결정결함층을 형성하므로써 연약한 부분으로 변하게되어 섬유의 물성을 저하시키곤 하였다.In particular, the fiber produced by the method according to the Japanese Patent Application No. 57-10885 is HCl produced during the synthesis of the initial polymer solution by the amine terminal of the polymer-

An ionic molecular chain end is formed, and this part forms a cluster during fiber formation, forming a node of crystal and turning into a weak part by forming a crystal defect layer perpendicular to the fiber axis. This lowered the physical properties of the fibers.

Accordingly, the inventors of the present invention have long reached a new and useful method for preparing aromatic polyamides, considering that the physical properties of the same compound vary greatly depending on the crystal structure.

For example, the present invention is an extrusion contact injection of the polymer solution before the gelation after the steer ophalation before the completion of the polymerization process, that is, the liquid crystal prepolymer with a tertiary amine or tertiary amine and an amide solvent and an external mixed solvent. It is an object of the present invention to provide an aromatic polyamide pulp upper fiber and a method for producing the same, which have high strength and high orientation by the molecular orientation polymerization method, as well as shorten the process, increase the intrinsic viscosity, and enable continuous production.

Hereinafter, the present invention will be described in detail.

In the present invention, an inorganic salt is added to the amide solvent to dissolve it, followed by polymerization of an equimolar amount of aromatic diamine and aromatic dieside chloride at a low temperature of 40 ° C. or lower, and having an intrinsic viscosity of 1.0 to 4.0, and the following structural formula (I) or ( After preparing an optically anisotropic liquid crystalline prepolymer having a repeating unit of II) and extruded through a blowing nozzle, a mixture of tertiary amine-based or tertiary amine-based and amide-based solvents was mixed at a shear rate of at least 50 sec ⁻¹ or higher. It is a method for producing an aromatic polyamide pulp top fiber characterized in that the final polymerization and molecular chain orientation are simultaneously performed by extrusion spraying at a low temperature using a solvent as a polymerization accelerator precipitater.

R ₁ and R ₂ may be the same or different, and R ₁ and R ₂ are generally present in equimolar amounts.

In addition, the present invention has a finely expanded molecular chain structure by sufficient molecular orientation polymerization method of the final fiber formed in contact with the nozzle jet at a shear rate of 50 sec ^-1 or more, the chain tip distribution in the neutral form while the fiber axis It is an aromatic polyamide pulp upper fiber which is uniformly distributed in the direction, there is no crystal defect layer in the fiber axis direction, has an intrinsic viscosity of 4.0 or more and a strength of 15 g / d or more.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

In the present invention, the preparation of the optically anisotropic liquid crystal prepolymer solution is prepared during the polymerization reaction by preparing a solution in which an inorganic salt is dissolved in an amide solvent and then adding an aromatic diamine and an aromatic dieside chloride, wherein the inorganic salt It is preferable to add and dissolve 0.5-15 weight% with respect to a silver polymerization solvent.

As a polymerization method of the liquid crystal prepolymer solution in the above composition, an aromatic diamine is dissolved in an amide solvent in which an inorganic salt (metal halide salt) is dissolved, and then cooled to low temperature under a nitrogen stream, and the aromatic dieside chloride is 40 ° C. or less. It is prepared by a solution polymerization method which reacts at low temperature, and at this time, the solvent and monomer should contain a minimum amount of impurities, and the reaction should proceed quantitatively.

As the polymerization solvent used in the present invention, an amide solvent or a urea solvent may be used alone, or two or more thereof may be mixed. For example, N-methyl-2-pyrrolidone (NMP), N, N -Dimethylacetamide (DMAc), hexamethylphosphoramide (HMPA) and the like are mainly used. In addition, N-methylpiperidone, N-methylcaprolactam, dimethylisobutylamide and the like can also be used.

On the other hand, lithium chloride, calcium chloride, potassium chloride, potassium bromide and the like are mainly used as inorganic salts, that is, halogenated metal salts in the polymerization solvent.

By the above polymerization composition, aromatic diamines, such as p-phenylenediamine and aromatic dieside chlorides, for example terephthaloyl chloride, which are monomers at low temperatures, are reacted to some extent by adding and stirring before the reaction is completed. The optically anisotropic liquid crystal prepolymer in the state is obtained as poly (p-phenylene terephthalamide) having the following structural formula (III).

Herein, the liquid crystal prepolymer solution may be used in an amount of 4 to 20% by weight, more preferably 5 to 15% by weight.

The intrinsic viscosity of the liquid crystal prepolymer may be 1.0 to 4.0, but more preferably 1.5 to 2.5 in terms of process control.

If the polymer content rate or intrinsic viscosity is high, it is difficult to use as a dope, and when extruded through the nozzle of the present invention, it is difficult to obtain the effects of the present invention. good.

On the other hand, Figure 1 is a process diagram showing an embodiment of the present invention to first supply a prepolymer solution to the nozzle jet (7) by operating the gear pump (4) attached to the transfer line (3) in the reactor (1) At the same time, the polymerization promoter precipitate stored in the storage tank 2 is supplied to the nozzle jet 7 along the feed line 6 through the circulation pump 5.

의 이온그룹을 충분히 중화시키므로써 액정예비중합체의 아민말단이 중성형태로 존재하게 되고 이와같은 중성의 아민말단기가 압출분사시 형성하게 되어 결정결함층이 섬유내에 존재하지 않는 펄프상단섬유를 형성하게 된다.The liquid crystal prepolymer introduced into the nozzle jet 7 by the transfer line 3 is introduced into the nozzle jet 7 at a shear rate of at least 50 sec ⁻¹ or more through the small hole of the nozzle jet 7. The injection is in contact with the accelerated precipitant to be polymerized in the ejection pipe (8). That is, the reaction rate rapidly increases by contact between the prepolymer solution passing through the nozzle jet 7, which is a pulp-like short fiber manufacturing apparatus, and the polymerization accelerator, and the intrinsic viscosity is markedly increased while the polymerization is completed. At this time, the orientation grows in the transfer line 6 due to the shearing force of the polymerization accelerator.

By sufficiently neutralizing the ionic groups of, the amine end of the liquid crystal prepolymer is present in a neutral form, and such a neutral amine end is formed during extrusion injection to form a pulp upper fiber in which the crystal defect layer does not exist in the fiber. .

2 is a schematic view showing an enlarged nozzle jet apparatus according to the present invention, wherein the nozzles used herein preferably have a ratio of a: b of 1: 3 to 1: 7 and "a" of 0.03 to 0.1 mm. It is good to have.

In the case of a slitting nozzle, a circular nozzle is preferably used with a diameter of 0.2 mm or less, more preferably 0.05 to 0.15 mm, and the number of nozzles is the shear force of the polymerization promoter. Depending on the installation, it is most suitable to use 20 to 500 pieces.

In this way, the liquid crystal prepolymer and the polymerization accelerator precipitated by the nozzle jet 7 for producing the pulp upper fiber are sufficiently contacted in the ejection pipe 8 by the molecular orientation polymerization method, and directly in the recovery tank 9. Polyamide pulp upper fibers having no crystal defect layer in the fiber are obtained.

In this case, the length of the ejection pipe 8 is generally required to be 1 to 50m in length because a sufficient time is required until the reaction of the prepolymer solution and the polymerization accelerator precipitant is completed.

On the other hand, the polymerization accelerator used in the above process generally includes tertiary amines, for example, pyridine, triethylamine, t-butylamine, picoline, quinoline, pyrimidine, pyrazine, quinoxaline Pyridine is the most effective polymerization precipitant for high intrinsic viscosity, orientation and sufficient neutralization efficiency. In addition, tertiary amines may be used alone as the polymerization promoter precipitate, but in order to increase the diffusion rate of the polymerization accelerator, the mixture may be partially mixed with an amide solvent such as NMP, DMAc or HAMPA.

The water content of the polymerization accelerator is preferably about 5000 ppm or less, and the temperature of the polymerization accelerator is generally preferably performed at a low temperature of 50 ° C or less.

On the other hand, the physical property evaluation of the pulp upper fiber prepared in accordance with an embodiment of the present invention can be easily seen from the intrinsic viscosity relationship shown in general.

Where C is the concentration of the polymer solution, ηrel is the relative viscosity, and the flow time ratio between the solution and the solvent measured with a capillary viscometer at a temperature of 30 ° C. The solvent used is usually concentrated sulfuric acid (95-98% H ₂ SO ₄ to be.

In addition, the characteristics of the compressive strength of the prepared pulp upper fiber was impregnated with epoxy resin in the fiber bundles by compression molding method and then compressed to extract the excess resin to prepare a composite having a high fiber content and harden the specimen. It can be easily known by converting the compressive strength of the fiber from the compressive strength of the composite by the results of the fabrication and measurement.

Therefore, it can be seen that the present invention is significantly different from the conventional method in the following points.

First, since the upper pulp fibers are produced directly during the polymerization process without the need for a secondary process of separating and washing the polymer in the polymer solution and preparing the dope of sulfuric acid, the process is simple and the manufacturing cost can be reduced.

Secondly, the molecular orientation polymerization method is carried out by extruding the liquid crystal prepolymer before the completion of polymerization in the polymerization process with a polymerization accelerator precipitant at a shear rate of 50 sec ⁻¹ or more through a nozzle of a small size to promote the polymerization and the molecular orientation at the same time. As a result, it is possible to obtain aromatic polyamide pulp upper fibers not only having high strength and high orientation but also having a microstructure of the fiber without a crystal defect layer.

On the other hand, according to such a difference in the manufacturing process, the pulp upper fiber product obtained by the present invention has a uniform distribution of the neutral amine end group does not form a crystal defect layer in the fiber has excellent characteristics of the fiber has excellent characteristics (See FIG. 4).

Third, even when a small amount of tertiary amine is included in the polymerization composition, a fiber without a crystal defect layer can be formed, but the polymerization rate is rapidly increased, whereas the present invention has a process control of the liquid crystal prepolymer solution. There is great utility in this respect.

Such an almost completely expanded aromatic polyamide fiber exhibits superior strength than conventional products. The present invention will be described in more detail based on examples.

Example 1

After purifying the reactor sufficiently with N ₂ to remove moisture, 250 ml of N-metal-2-pyrrolidone was added, and after raising the temperature, calcium chloride (CaCl ₂ ) was added as an inorganic salt and dissolved. After dissolving 10.38 g of p-phenylene diamine in an amide polymerization solvent in which an inorganic salt is dissolved, 19.55 g of terephthaloyl chloride (TPC) is added at a low temperature of 30 ° C. or lower and stirred vigorously. Is sent to the nozzle jet device through a 1/2 inch feed pipe at a speed of 2 m / min using a gear pump in the reactor.

At this time, the size of the nozzle was 0.1 x 0.35 mm and the number of nozzles was 50.

The pyridine is extruded through the transfer pipe to the nozzle jet apparatus at a speed of 20 m / min with a transfer pump immediately after the liquid crystal prepolymer solution is started to the nozzle jet apparatus. The liquid crystal prepolymer solution and pyridine contacted each other in the nozzle jet apparatus are extruded through a transfer line having a length of 5 m. The extruded pulp-like short fibers and pyridine are filtered by a filtering device, and the pulp-like short fibers are circulated, and the filtrate, pyridine, is circulated, and the pulp-like short fibers are dried in a vacuum drying apparatus at a temperature of 110 ° C. for 5 hours. . At this time, 1.V. of the final pulp-like short fiber was 6.3 and the compressive strength was 27kg / mm 2.

Example 2 [Comparative Example 1]

This example shows the results of manufacturing short fibers according to the polymerization accelerator and precipitation solution as shown in Table 1 below, and the results are shown in Table 1 below. The preparation and extrusion conditions of the prepolymer solution are the same as in Example 1.

TABLE 1

Example 3

This embodiment shows the results of the preparation of pulp-like short fibers according to the specifications of the nozzles used in the extrusion injection of the liquid crystal prepolymer and the polymerization promoter precipitate, the results are shown in Table 2 below. At this time, the preparation of the prepolymer solution except the shape, size, number of nozzles and the extrusion aid is the same as in Example 1.

TABLE 2

Example 4

This embodiment shows the results of the pulp upper fiber in accordance with the shear force of the polymerization promoter precipitate, the results are shown in Table 3 below. At this time, the device conditions except for the shearing force of the polymerization accelerator is similar to the device conditions of Example 1, the transfer pipe 6 uses a 1/2 inch transfer pipe, the nozzle size is 0.05 × 0.35 mm slit type The number is 100.

TABLE 3

Comparative Example 2

A prepolymer solution was prepared according to the same polymerization composition and conditions as in Example 1, but was carried out until the viscosity of the reactant reached 100 to 200 poise, followed by spinning spinneret having 100 pores 0.3 mm in diameter. Extruded through a coagulation bath to obtain a fibrous material, washed with water and dried to measure the overall physical properties. The I.V. of the fibrous material obtained through the coagulation bath of pyridine is 4.5. The strength is 9.6 g / d, and the compressive strength of the fiber converted by the compression molding method is 17 kg / mm 2.

Claims (5)

In order to prepare an aromatic polyamide pulp-like short fiber having no crystal defect layer in the fiber by dissolving an inorganic salt in an id solvent and adding aromatic diamine and aromatic dieside chloride, the inorganic salt is dissolved in an amide solvent. Inorganic salts dissolve 0.5 to 15% by weight, where the intrinsic viscosity is 1.0 to 4.0 before the complete polymerization at low temperature below 40 ° C. by adding equimolar amounts of aromatic diamine and aromatic dieside chloride, and the following structural formula (I) or (II) After preparing an optically anisotropic liquid crystal prepolymer having a repeating unit of), the liquid crystal prepolymer is extruded through an ejection nozzle and polymerized with a tertiary amine-based solvent or a mixed solution with an amide solvent at a low temperature of 50 ° C. or lower. final island extruded with the accelerator jet without determining the bonding layer by the above at least 50sec ^-1 shear force by polymerization accelerator The method of the aromatic polyamide pulp, the short fibers, characterized in that is obtained.

Wherein, R ₁ and R ₂ may be the same or different, and R ₁ and R ₂ are generally present in equimolar amounts. The method of claim 1 wherein the inorganic salt is selected from calcium chloride, lithium chloride, potassium chloride or potassium bromide. The method of claim 1, wherein the polymerization accelerator is a pyridine, triethylamine, quinoline, pyrimidine, pyrazine, quinoxaline alone or mixed with at least one of NMP, DMAc, HMPA. The method according to claim 1, wherein a nozzle jet device is used as the extrusion jet device. Aromatic polyamide pulp, characterized in that the microstructure of the fiber has a fully extended molecular chain structure by molecular orientation polymerization method, in which the end groups of the amine are uniformly distributed and has an intrinsic viscosity of 4.0 or more. fiber.

Images