KR100422465B1 - Wholly aromatic polyamide fibers and production thereof - Google Patents

Abstract

PURPOSE: A method of making wholly aromatic polyamide fibers by spinning a spinning dope of wholly aromatic polyamide fibers that are easily dissolved in polar organic solvent is provided. It does not use sulfuric acid and thus solves conventional problems such as equipment corrosion, harmfulness of working environment, a rise in manufacturing cost or the like in accordance with the use of sulfuric acid. CONSTITUTION: The wholly aromatic polyamide fibers have a formula(I) and a tensile strength of 10g/d or more. In formula, n is an integer of more than 1. They are prepared by the following process: producing a spinning dope by polymerizing aromatic diamine of formula(II) and aromatic diacid halide in the presence of a polymerization solvent, adding an inorganic alkali compound to neutralize an acid generated during the polymerization reaction; and then spinning it. The aromatic diacid halide is terephthaloyl fluoride. The polymerization solvent is an amide-based solvent, urea-based solvent or a mixed solvent thereof.

Description

Wholly aromatic polyamide fibers and methods for their preparation.

The present invention relates to wholly aromatic polyamide fibers and a process for their preparation. More specifically, the present invention relates to a wholly aromatic polyamide fiber prepared by spinning a wholly aromatic polyamide spinning dope which is easily dissolved in a polar organic solvent, and a method of manufacturing the same.

In general, wholly aromatic polyamide fibers have excellent mechanical strength, elastic modulus and heat resistance. In particular, para-based polyaromatic polyamide polymers, represented by poly paraphenylene terephthalamide (hereinafter referred to as PPTA), are widely used in special industrial fields such as industrial materials, aircraft or automobile industry composite materials, building materials, leisure and sporting goods. have.

However, when producing moldings from PPTA, it is difficult to prepare moldings because PPTA is not soluble in solvents.

For example, in order to prepare a PP7A polymerization solution for the production of PPTA fibers, films or other moldings, a concentrated sulfuric acid solution should be used, resulting in problems such as device corrosion, process increase, cost increase, and environmental pollution.

That is, a large amount of neutralizing agent is used to neutralize the sulfuric acid contained in the molding, and as a result, it contains inorganic salts, which lowers the quality of the product and increases the manufacturing cost as the inorganic salts are removed. In addition, the use of sulfuric acid can cause environmental pollution and process management is difficult.

In addition, it is also difficult to produce high concentration of polymerized dope with substantially 20% by weight of polymer.

In order to improve such a problem, many studies have been conducted on the preparation of para-type wholly aromatic polyamide polymers in which molding dope for molding can be prepared using a general polar organic solvent. For example, Japanese Patent Laid-Open Nos. 51-76386, 51-134743, 51-1l36916, 6161222229, 62-27431, 62-225530, 62-177002 and 62- 177023 et al. Attempted to achieve the above object by introducing ether bonds into the wholly aromatic polyamide chains. As a result, the effect of dissolving the polymer well in the polar organic solvent can be obtained, but there is a problem that the prepared polymer does not have sufficient heat resistance and strength due to the ether bond introduced into the aromatic polyamide chain.

This can be expected to be the result of the zigzag shape of the primary structure of the polymer chain due to ether bonding.

Meanwhile, U.S. Patent No. 5006629 and 5274071 disclose a method of copolymerizing a monomer having a repeating unit and a monomer having a diamine repeating unit such as a benzidinediamine containing a substituent or a diamine having an ether bond.

The wholly aromatic polyamide polymer prepared in this way has not been commercialized to date because it does not have sufficient solubility in polar organic solvents.

In order to solve the problems of the prior art described above, the present invention provides a wholly aromatic polyamide fiber which does not have to use sulfuric acid by producing a spinning dope for molding having excellent solubility in polar organic solvents without deteriorating heat resistance and strength. By providing a method, it is intended to solve the problems such as corrosion of the device, harm of working environment, and increase of manufacturing cost.

The present invention relates to a wholly aromatic polyamide fiber and a method for producing the same. Specifically, the present invention relates to a wholly aromatic polyamide fiber having a tensile strength of 10 g / d or more and having a structure of the following structural formula (I).

[N is an integer of 1 or more in formula (I)]

In addition, the present invention is to polymerize the aromatic diamine and the aromatic dieside halide of the following structural formula (II) under a polymerization solvent, and optionally by adding an inorganic alkali compound to neutralize the acid generated during the polymerization reaction to prepare a spinning dope, and then spin it An example of a method for producing a wholly aromatic polyamide fiber characterized in that.

The manufacturing method of the present invention will be described in more detail.

1) adding and dissolving the aromatic diamine of the structural formula (II) in a polymerization solvent comprising an amide organic solvent, a urea organic solvent, or a mixed organic solvent thereof;

2) The temperature of the solution is maintained at 0 ~ 30 ℃ and polymerized by the addition of aromatic dieside halide with vigorous stirring,

3) Alkali metal of LiCO ₃ , CaCO ₃ , LiH, CaH ₂ , LiOH, Ca (OH) ₂ , Li ₂ O or CaO after polymerization, carbonate of alkaline earth metal, hydride of alkaline earth metal, hydroxide of alkaline earth metal, or alkali By selectively adding an inorganic alkali compound selected from the group consisting of earth metal oxides to neutralize the acid generated during the polymerization reaction to prepare a spinning dope,

4) Spinning the prepared spinning dope to prepare a wholly aromatic polyamide fiber.

In the present invention, the spinning dope may be prepared by dissolving the wholly aromatic polyamide polymer prepared by the steps 1) to 3) described above in a polar organic solvent. The spinning dope prepared in this way may be spun to produce a wholly aromatic polyamide fiber.

In the present invention, as the organic solvent, an amide organic solvent, a urea organic solvent, or a mixed solvent thereof is used. Especially N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAc), hexamethylphosphoamide (HMPA), N, N, N ', N'-tetramethyl urea (TMU) Preference is given to using N, N-dimethylformamide (DMF) or mixtures thereof.

In addition, an inorganic salt may be selectively added to the polymerization solvent used in the present invention in order to increase the solubility and polymerization degree of the aromatic polyamide. Representative examples of such inorganic salts include halogenated alkali metal salts or halogenated alkaline earth metal salts such as CaCl ₂ , LiCl, Nacl, KCl, LiBr and KBr. These inorganic salts may be added alone or in the form of a mixture of two or more kinds.

The amount of the inorganic salt added is preferably in the range of 5% by weight or less based on the total amount of the polymerization solvent. When the added amount of the inorganic salt exceeds 5% by weight, the objective effect of the present invention can no longer be expected and becomes uneconomical.

In the present invention, it is preferable to use 1,4-bis (4-amino phenylcarboxamido) cyanobenzene as the aromatic diamine and terephthaloyl chloride as the dieside halide.

Aromatic dieside halides having dicarbonyl repeating units in the production of polyamide polymers react with aromatic diamines in a 1: 1 molar ratio, but in order to control the degree of polymerization of the resulting polymer, one component may be added in excess of the molar ratio.

After the polymerization is completed, the addition of the inorganic alkali compound is intended to neutralize the acid generated during the polymerization and increase the solubility of the gelled polymer into a viscous solution. In order to maintain a constant viscosity of the spinning dope prepared above, the concentration and degree of polymerization of the polymer and the inorganic salt in the spinning dope are important variables. The polymer concentration in the dope is preferably 5 to 30% by weight, more preferably 10 to 25% by weight can be produced a dope having a uniform physical properties. At this time, the intrinsic viscosity has a range of 3 to 10.

At the time of superposition | polymerization, since reaction of an aromatic dieside halide and an aromatic diamine advances very quickly, it is preferable to maintain the temperature of a polymerization system in the range of 0-30 degreeC. It is also important to prevent contamination with water and other impurities that can terminate the polymerization.

The thus-produced wholly aromatic polyamide polymer of the present invention has a very high solubility in a polymerization solvent, thereby forming a stable spinning dope. There is no change in viscosity even if the spinning dope with a polymer concentration in the range of 5--30% is left for a week. When the stable spinning dope is spun into the coagulation bath directly through the spinneret, it is possible to easily prepare high-strength and high elasticity wholly aromatic polyamide fibers.

In addition, the wholly aromatic polyamide spinning dope system according to the present invention does not contain sulfuric acid, so that the degree of polymerization of the polymer is not lowered, and the manufacturing cost increases due to the recovery of sulfuric acid due to the use of sulfuric acid, corrosion of equipment by sulfuric acid, risk of working The disadvantages of the process of using the same sulfuric acid can be solved.

The tensile strength of the wholly aromatic polyamide fiber of the present invention is 10 g / d or more, and has the structure of the following formula (I).

[N is an integer of 1 or more in formula (I)]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited only to the examples.

Example 1

1) 1, 4-bis (4-amino phenylcarboxamido) cyanobenzene preparation

a) Preparation of 1, 4-bis (4-amino phenylcarboxamido) cyanobenzene

(Molecular weight: 445.40)

Under nitrogen stream, 500 g of dimethylacetamide (hereinafter referred to as DMAc) was dissolved in a mechanical stirrer while adding 13.3 g (0.1 mol) of 2-cyanoparaphenylene diamine, and then cooled to 7 ° C. using a cooling bath.

After cooling, 37.2 g (0.2 mol) of 4-nitrobenzoyl chloride was added while increasing the stirring speed. Continue stirring for 30 minutes, then add DMAc to dissolve completely and filter. 5% aqueous sodium carbonate solution is added to the filtrate and stirred to neutralize. Distilled water was further added to precipitate, filtered, washed with water, washed with acetone, and filtered. The resultant was dried at a temperature of 80 ° C. in a vacuum oven, and 42.82 g of 1,4-bis (4-amino phenylcarboxamido) cyanobenzene was obtained. The yield is 99%.

b) Preparation of 1,4'-bis (4-amino phenylcarboxamido) cyanobenzan

(Molecular weight: 371.43)

To 600 ml of dimethylacetamide, add 120 g of 1,4-bis (4-nitrophenylcarboxamido) cyanobenzane and add 12 g of paradium / carbon (5%) with stirring. The hydrogen pressure is 7.5 Kg / cm ² and reacted at room temperature to react with stirring until the hydrogen pressure no longer decreases. After completion of the reaction, it was filtered and precipitated by adding distilled water to the separated filtrate. The product is separated by refiltration, washed with acetone and dried. The resultant 1, 4-bis (4-amino phenylcarboxamido) cyanobenzene was 31.71 g and the yield was 95%.

2) Preparation of Aromatic Polyamide Fiber (Molecular Weight: 501.53)

180 ml of dimethylacetamide (DMAc) and 7 g of LiCl were added to a completely dried three-necked flask under nitrogen stream to dissolve completely, and then 1,4-bis (4-amino phenylcarboxamido) cyanobenzene was stirred. Dissolve 25.87 g completely. After the temperature of the solution is lowered to about 10 ° C., 14.14 g of terephthaloyl chloride (hereinafter referred to as TPC) is added at once with vigorous stirring. A polymerization solution having a viscosity immediately after addition was prepared.

The polymer solution was degassed with a vacuum pump and then extruded and sprayed into a 5 mm air gun at a pressure of 10 Kg / cm ² through a 0.06 mm spinneret and spun into a 20% aqueous dimethylacetamide solution at about 5 ° C. It solidifies and winds up in a roller at the speed of 100 m / min. After washing the fiber sufficiently with distilled water, it is dried at 150 ℃ to produce a fiber. The inherent viscosity of the wholly aromatic polyamide fibers thus prepared was 8.2, and the tensile strength was 22 g / d.

Examples 2-6

A wholly aromatic polyamide fiber was prepared under the same conditions as in Example 1 except that the production conditions were changed as shown in Table 1. Table 1 shows the results of measuring the intrinsic viscosity and tensile strength of the fabric.

<Table 1> Manufacturing Conditions and Fiber Properties

The method of evaluating the intrinsic viscosity is as follows.

Inherent Viscosity (Inherent Viscosity: I. V)

LV (g / dl) = ln (η _rel ) / C

Where C is the concentration of the polymer solution (solution in which 0.5 g of the polymer is dissolved in 100 ml of 95-98% concentrated sulfuric acid), and the relative viscosity η _rel is the ratio of the flow time measured by a capillary viscometer at a temperature of 30 ° C., and the solvent is 95 It is -98% concentrated sulfuric acid.

The wholly aromatic polyamide fibers of the present invention do not need to use sulfuric acid in preparation by using a spinning dope having excellent solubility in polar organic solvents without a decrease in heat resistance and strength. As a result, it is possible to solve the conventional problems such as corrosion of the device due to the use of sulfuric acid, hazards of the working environment and increase in manufacturing cost. In addition, the wholly aromatic polyamide fibers have a strength of 10 g / d or more and excellent heat resistance.

Claims (7)

The wholly aromatic polyamide fiber which has a structure of the following structural formula (I).

[N is an integer of 1 or more in formula (I)] The wholly aromatic polyamide fiber of claim 1 having a tensile strength of at least 10 g / d. The aromatic diamine of the following formula (II) and the aromatic dieside halide are polymerized under a polymerization solvent, and optionally, an inorganic alkali compound is added to neutralize the acid generated during the polymerization reaction to prepare a spinning dope and to spin it. Method for producing wholly aromatic polyamide fibers.

The process for producing the wholly aromatic polyamide fiber according to claim 3, wherein the aromatic dieside halide is terephthaloyl fluoride. The method for producing a wholly aromatic polyamide fiber according to claim 3, wherein the polymerization solvent is an amide solvent, a urea solvent or a mixed solvent thereof. The method for producing a wholly aromatic polyamide fiber according to claim 3 or 5, wherein an inorganic salt is added to the polymerization solvent. 4. The wholly aromatic poly according to claim 3, wherein the inorganic alkali compound is at least one compound selected from the group consisting of alkali metals, carbonates of alkaline earth metals, hydrides of alkaline earth metals, hydroxides of alkaline earth metals and oxides of alkaline earth metals. Method for producing amide fibers.