KR101309466B1 - Method of making Aromatic Polyamide polymer, Aramid Fiber and method of making Aramid Fiber - Google Patents

Abstract

The present invention relates to a process for producing a polymerization solvent, Dissolving aromatic diamine in the polymerization solvent to prepare a mixed solution; And adding an aromatic dieside halide to the mixed solution to polymerize the aromatic diamine and an aromatic dieside halide, wherein the polymerization solvent has a transmittance of 70% or more. A method for producing a polymer, aramid fibers and aramid fiber manufacturing method using the method,

According to the present invention, an aromatic polyamide polymer having an L value of 60 or more can be obtained by using a polymerization solvent having a transmittance of 70% or more, and the aramid fibers finally obtained by performing a spinning process using such an aromatic polyamide polymer. Color properties can be improved, resulting in improved productability of aramid fibers.

Aramid fiber, color, L value

Description

Method for Making Aromatic Polyamide Polymer, Aramid Fiber and Method for Making the A {{Method of Making Aromatic Polyamide Polymer, Aramid Fiber and Method of Making Aramid Fiber}

The present invention relates to an aramid fiber, and more particularly to an aramid fiber having improved color characteristics and a method for producing the same.

In general, the aromatic polyamide fibers commonly referred to as aramid fibers are prepared by polymerizing an aromatic diamine and an aromatic diacid chloride in a polymerization solvent containing N-methyl-2-pyrrolidone to prepare an aromatic polyamide polymer, Preparing a spinning dope by dissolving a polyamide polymer in a concentrated sulfuric acid solvent and spinning the spinning dope through a spinneret and then solidifying the spinning solution to produce a filament.

The aramid fiber includes para-aramid fibers having a structure in which benzene rings are linearly connected through an amide group (CONH) and meta-based aramid fibers not having a structure. Para-aramid fibers have excellent properties such as high strength, high elasticity and low shrinkage. They have a strong strength enough to lift 2 tons of automobile with a thin thread of 5mm thickness, Of-the-art industry. In addition, since the aramid fiber is carbonized at a temperature of 500 ° C or higher, the aramid fiber is also in the spotlight where high heat resistance is required.

Such aramid fibers have a variety of applications as special fibers having high-performance physical properties, but conventional aramid fibers have a limitation in degrading color characteristics and inferior product properties.

The present invention has been devised to solve the above-mentioned conventional problems, and the present invention provides a method for producing an aromatic polyamide polymer for obtaining aramid fibers having improved color characteristics, a method for producing aramid fibers using the method, and the method It is an object to provide the produced aramid fibers.

In order to achieve the above-mentioned object, the present invention provides a process for producing a polymerization solvent, Dissolving aromatic diamine in the polymerization solvent to prepare a mixed solution; And adding an aromatic dieside halide to the mixed solution to polymerize the aromatic diamine and an aromatic dieside halide, wherein the polymerization solvent has a transmittance of 70% or more. Provided are methods for preparing a polymer.

At this time, the step of preparing a polymerization solvent having a transmittance of 70% or more may include a step of adjusting the content of Fe contained as impurities in the polymerization solvent to 5 ppm or less.

The present invention also provides a process for preparing an aromatic polyamide polymer having an L value of 60 or more; Dissolving the aromatic polyamide polymer in a solvent to prepare a radial dope; And a step of irradiating the radiation dope.

The present invention also provides an aramid fiber characterized by having an amide bond of at least 85% and an L value of 80 or more.

The inventors of the present invention have investigated a method for obtaining aramid fibers having improved color characteristics, and confirmed that the color characteristics of aromatic polyamide polymers have a great influence on the color characteristics of aramid fibers finally obtained. Therefore, further studies have been conducted to improve the color characteristics of the aromatic polyamide polymer, and as a result, it is possible to improve the color characteristics of the aromatic polyamide polymer by improving the permeability characteristics of the polymerization solvent for preparing the aromatic polyamide polymer. Specifically, it was found that when controlling the permeability of the polymerization solvent to 70% or more, the L value of the aromatic polyamide polymer became 60 or more, thereby improving color characteristics of the finally obtained aramid fiber.

In addition, as a result of further studies on the method to make the permeability of the polymerization solvent to 70% or more, it was confirmed that the content of Fe contained as an impurity in the polymerization solvent affects the permeability of the polymerization solvent. When the content of 5ppm or less to control the polymerization solvent having a transmittance of 70% or more was confirmed to complete the present invention.

In summary, the present invention controls the content of Fe contained as impurity in the polymerization solvent to be 5 ppm or less to obtain a polymerization solvent having a transmittance of 70% or more, and by performing the polymerization process using such a polymerization solvent, the L value is 60. By obtaining an aromatic polyamide polymer as described above and performing a spinning process using the aromatic polyamide polymer, the finally obtained aramid fibers have an L value of 80 or more to improve the color characteristics.

According to the present invention as described above, the following effects can be obtained.

According to the present invention, an aromatic polyamide polymer having an L value of 60 or more can be obtained by using a polymerization solvent having a transmittance of 70% or more, and an aramid fiber having an L value of 80 or more by performing a spinning process using such an aromatic polyamide polymer. Can be obtained. Therefore, the color characteristics of the final aramid fibers are improved, and the productability of the aramid fibers is improved.

Hereinafter, preferred embodiments of the present invention will be described in detail.

1. Preparation of aromatic polyamide polymer

1) First, a polymerization solvent is prepared.

The polymerization solvent is prepared by adding an inorganic salt to an organic solvent.

The organic solvent may be an amide organic solvent, a urea organic solvent or a mixed organic solvent thereof. Specific examples thereof include N-methyl-2-pyrrolidone (NMP), N, N'-dimethylacetate Amide (DMAc), hexamethylphosphoramide (HMPA), N, N, N ', N'-tetramethylurea (TMU), N, N-dimethylformamide (DMF) or mixtures thereof.

The inorganic salt is added in order to increase the polymerization degree of the aromatic polyamide. Specific examples thereof include alkali metal halides such as CaCl ₂ , LiCl, NaCl, KCl, LiBr and KBr, or alkaline earth metal halides. The salts may be added alone or in the form of a mixture of two or more. As the addition amount of the inorganic salt increases, the degree of polymerization of the aromatic polyamide increases. However, since an inorganic salt which does not dissolve when the inorganic salt is added in an excessive amount may be present, the inorganic salt may be present in an amount of 10% .

The polymerization solvent prepared by adding an inorganic salt to the organic solvent has a transmittance of 70% or more, so that the content of Fe contained as impurities in the polymerization solvent is 5 ppm or less in order to have a transmittance of 70% or more. In particular, calcium chloride may be used as the inorganic salt, and N-methyl-2-pyrrolidone (NMP) may be used as the organic solvent. In the case of the calcium chloride, Fe may be included as an impurity during the manufacturing process. By controlling the process so that the content of Fe contained in the content is 5 ppm or less, the content of Fe in the polymerization solvent can be 5 ppm or less.

2) Next, a mixed solution is prepared by dissolving the aromatic diamine in the polymerization solvent.

Specific examples of the aromatic diamine include para-phenylenediamine, 4,4'-diaminobiphenyl, 2,6-naphthalenediamine, 1,5-naphthalenediamine or 4,4'-diaminobenzanilide However, the present invention is not limited thereto.

3) Next, a predetermined amount of aromatic di-halide halide is added to the mixed solution while stirring the mixed solution to pre-polymerize.

Polymerization of an aromatic diamine and an aromatic diacid halide proceeds at a rapid rate with the exothermic reaction. When the polymerization rate is increased as described above, there arises a problem that the difference in degree of polymerization between the finally obtained polymers increases. More specifically, since the polymerization reaction does not proceed at the same time in the entire mixed solution, the polymer in which the polymerization reaction is initiated first rapidly undergoes a polymerization reaction to form a long molecular chain, The shorter the molecular chain, the faster the polymerization rate becomes. As described above, when the difference in degree of polymerization between the finally obtained polymers becomes large, the physical property deviation becomes large, which makes it difficult to realize the desired characteristics.

Thus, through the prepolymerization process, a polymer having a molecular chain of a predetermined length is formed in advance, and then a polymerization process is performed to minimize the difference in degree of polymerization between the finally obtained polymers.

Specific examples of the aromatic diacid halide include terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalene dicarboxylic acid dichloride and 1,5-naphthalene dicarboxylic acid dichloride, But is not limited thereto.

4) Then, after completion of the prepolymerization step, the remaining amount of the aromatic diacid halide is added to the mixed solution while stirring at 0 to 30 ° C for polymerization.

Since the aromatic diacid halide reacts with the aromatic diamine in a 1: 1 molar ratio in the production of the aromatic polyamide, the aromatic diamine and the aromatic diacid halide can be added at the same molar ratio.

It is preferable to adjust the amount of the aromatic diamine and the di-halide halide so that the concentration of the final polymer in the entire polymerization solution is about 5 to 20% by weight after completion of the polymerization process. When the aromatic diamine and the di-halide halide are added so that the concentration of the final polymer is less than 5% by weight, the polymerization rate is lowered and the reaction is required to be carried out for a long period of time, resulting in poor economical efficiency. And dieside halide are added, the polymerization reaction does not progress smoothly and the intrinsic viscosity of the polymer can not be improved to 5.5 or more.

Specific examples of the aromatic polyamide polymer obtained by the polymerization process include poly (paraphenylene terephthalamide: PPD-T), poly (4,4'-benzanilide terephthalamide), poly '-Biphenylene-dicarboxylic acid amide) or poly (paraphenylene-2,6-naphthalene dicarboxylic acid amide).

5) Next, an alkali compound is added to the obtained aromatic polyamide solution to neutralize the acid generated during the polymerization reaction.

When the polymerization reaction proceeds, an acid such as hydrochloric acid is generated. Such an acid causes problems such as corrosion of the polymerization apparatus. Therefore, an inorganic alkali compound or an organic alkali compound is added during or after the polymerization reaction, .

At this time, since the aromatic polyamide obtained through the polymerization reaction exists in the form of bread crumbs, the flowability of the aromatic polyamide solution is poor. Therefore, in order to improve the flowability, it is preferable to add water to the aromatic polyamide solution to prepare a slurry, and then carry out the subsequent step. For this purpose, water is added to the aromatic polyamide solution in an aromatic polyamide solution, The process can be carried out.

The inorganic alkaline compound may be at least one selected from the group consisting of alkaline metals such as NaOH, Li ₂ CO ₃ , CaCO ₃ , LiH, CaH ₂ , LiOH, Ca (OH) ₂ , Li ₂ O or CaO, carbonates of alkaline earth metals, hydrides of alkaline earth metals, Hydroxide, or an oxide of an alkaline earth metal.

6) Next, the aromatic polyamide polymer from which the acid has been removed is pulverized by completing the neutralization process.

If the particle size of the polymer is too large in the extraction process described later, the polymerization solvent extraction process takes a lot of time and the polymerization solvent extraction efficiency is lowered, so that the grinding process is performed to reduce the particle size of the polymer before the extraction process.

7) Next, the polymerization solvent contained in the aromatic polyamide polymer is extracted to remove the polymerization solvent from the polymer.

Since the aromatic solvent used for the polymerization process is contained in the aromatic polyamide polymer obtained by the polymerization, such a polymerization solvent must be extracted from the polymer, and the extracted polymerization solvent is reused in the polymerization process.

Such an extraction process is most effective and economical to perform using water. The extraction process may include a step of installing a filter in a bath equipped with an outlet, placing the polymer on the filter, pouring water, and discharging the polymerization solvent contained in the polymer together with water to the outlet.

8) Next, water remaining after the extraction process is dewatered, and then drying is completed to prepare the aromatic polyamide polymer. Thereafter, a classification process may be performed to classify the aromatic polyamide polymers by size for the spinning process.

The aromatic polyamide polymer obtained by such a method will have an L value of 60 or more.

2. Aramid  Manufacture of fibers

1) First, a spinning dope is prepared by dissolving the aromatic polyamide polymer produced by the above method in a solvent.

The solvent may be a concentrated sulfuric acid solvent having a concentration of 97 to 100%. In place of the concentrated sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, and the like may also be used.

The polymer concentration in the spin dope is preferably 10 to 25% by weight for the fiber properties. As the polyamide polymer concentration increases, the viscosity of the spin dope increases, but beyond the critical concentration point, the viscosity of the spin dope decreases rapidly, with the spin dope forming an optical phase without forming a solid phase. It changes from isotropic to optically anisotropic. Since the anisotropic spin dope can be made of high strength aramid fibers due to its structural and functional properties without a separate drawing process, it is preferable that the concentration of the polyamide polymer in the spinning dope exceeds the above critical concentration, but the concentration is excessively high. If large, the viscosity of the spinning dope is too low occurs.

2) Next, the spinning dope is spinned using a spinneret, followed by solidification in a coagulation bath through an air gap to form a filament.

The air gap may be mainly an air layer or an inert gas layer, the length of the air gap is 0.1 to 15 cm is preferable for improving the physical properties of the filament is produced.

The spinneret has a plurality of capillaries having a diameter of 0.1 mm or less. If the diameter of the capillary formed in the spinneret exceeds 0.1 mm, the molecular orientation of the resulting filament is poor, resulting in a decrease in the strength of the filament.

The coagulation bath is located at a lower portion of the spinneret, and a coagulation bath is stored in the lower portion of the coagulation bath. Therefore, the radiation passing through the capillary of the spinneret goes down while the air gap and the coagulating solution sequentially pass to form a filament. The filament is discharged through the coagulation tube under the coagulation bath. Since the coagulating liquid along with the filament is also discharged through the coagulating tube, the coagulating liquid should be continuously supplied to the coagulating bath as much as the discharged liquid.

In addition, the coagulation tube is formed with a jet device (jet device) can be injected to the filament passing through the coagulation tube. The injector has a plurality of jet openings and injects the coagulation liquid from the plurality of injection openings toward the filament. The plurality of injection holes are preferably aligned so that the coagulating liquid can be sprayed in perfect symmetry with respect to the filament. The jetting angle of the coagulating liquid is preferably 0 to 85 DEG with respect to the axial direction of the filament, and particularly preferably 20 to 40 DEG in the commercial production process.

The coagulating solution may be added with sulfuric acid to water, ethylene glycol, glycerol, alcohol, or a mixture thereof, and is maintained at -20 to + 90 ° C. When the radiation passing through the spinneret passes through the coagulation solution, the sulfuric acid in the radiation is removed and the filament is formed. When the sulfuric acid is abruptly removed from the surface of the radiation, the surface first coagulates In order to solve such a problem, sulfuric acid is added to form a coagulating solution.

3) Next, the sulfuric acid remaining in the obtained filament is removed.

Since a sulfuric acid solution is used in the preparation of the radial dope, sulfuric acid may remain in the filament produced by the spinning process.

The sulfuric acid remaining in the filament can be removed through a washing process using water or a mixed solution of water and an alkali solution.

The washing process may be carried out in a multi-step process, for example, primary washing with a sulfuric acid-containing filament with 0.3 to 1.3% of an aqueous caustic solution, followed by 0.01 to 0.1% of a thinner caustic solution You can do a second flush.

4) Next, a drying process is performed to adjust the moisture content remaining in the filament.

The drying process may control the time for which the filament is in contact with the heated drying roll, or the moisture content of the filament by adjusting the temperature of the drying roll.

On the other hand, during the spinning, washing, neutralizing and drying processes, tension is applied to the filament. The optimum amount of tension applied to the filament during the drying process is about 3.0 to 7.0 gpd It is preferable to dry the filament under a tensile force of. When the tensile strength at the time of drying is less than 3.0 gpd, the degree of molecular orientation is decreased and ultimately the strength of the fiber is lowered. Conversely, if the tensile strength during drying exceeds 7.0 gpd, the filament may be cut, resulting in difficulty in manufacturing. On the other hand, the magnitude of the tension applied to the filament can be adjusted by appropriately controlling the surface speed of the roll moving the filament.

The drying rolls are heated by some means, and the drying rolls are preferably at least partly surrounded by heat blocking means in order to prevent excessive heat from being released from the heated rolls and thereby causing heat loss.

5) Next, the dried filament is wound around the branch tube. Spinning speed is 600 to 1500 m / min. The obtained aramid fibers will have an L value of 80 or more, thereby improving color characteristics.

3. Example  And Comparative example

Various CaCl ₂ was added to N-methyl-2-pyrrolidone (NMP) to prepare various polymerization solvents having different Fe contents as shown in Table 1 below. The content of Fe in the polymerization solvent was measured using an ICP OES equipment (manufacturer: PERKIN ELMER) whose model name is Perkin elmer optima 5300 DV.

Thereafter, para-phenylenediamine was dissolved in the polymerization solvent to prepare a mixed solution. Thereafter, while stirring the mixed solution, terephthaloyl dichloride of the same mole as the para-phenylenediamine was added to the mixed solution in two portions to produce a poly (paraphenylene terephthalamide) polymer. Thereafter, water and NaOH were added to the polymerization solution containing the polymer to neutralize the acid. Thereafter, after pulverizing the polymer, the polymerization solvent contained in the aromatic polyamide polymer was extracted using water, and finally, the aromatic polyamide polymer was obtained through a dehydration and drying process.

Thereafter, the obtained aromatic polyamide polymer was dissolved in 99% concentrated sulfuric acid to prepare spinning dope. The polymer concentration in the radial dope was 20% by weight. Thereafter, the spinning dope was radiated through a spinneret, passed through a 7 mm air layer, and solidified while passing through a coagulation bath containing an aqueous solution of sulfuric acid and a coagulation tube below the coagulation bath to produce a filament. During the passage of the coagulation tube, an aqueous sulfuric acid solution was sprayed onto the filament through the injector. Thereafter, the filament was washed with water to remove residual sulfuric acid, dried, and then wound to obtain an aramid fiber.

Table 1

division Fe content in the polymerization solvent (ppm) Example 1 5 Example 2 4 Comparative Example 1 6

4. Experimental Example

1) Measurement of Permeability of Polymer Solvent

Samples of the polymerization solvents obtained during the production process according to Examples 1, 2, and Comparative Example 1 were obtained, each using a UV-Visible Spectrometer (manufacturer: HP) having the model name Agilent 8453. The visible light transmittance for the sample was measured. The results are shown in Table 2.

Table 2

division Permeability (%) Example 1 72 Example 2 81 Comparative Example 1 62

2) Determination of L value of aromatic polyamide polymer

Samples of the aromatic polyamide polymer obtained during the production process according to Examples 1, 2, and Comparative Example 1 were obtained, and the L value for each sample was obtained using a colorimeter (manufacturer: Minolta) whose model name was Chromater CR-300. Was measured. The results are shown in Table 3.

TABLE 3

division L value Example 1 63 Example 2 67 Comparative Example 1 50

3) L value measurement of aramid fibers

For the aramid samples prepared according to Example 1, Example 2, and Comparative Example 1, the L value for each sample was measured using a colorimeter (manufacturer: Minolta) whose model name was Chromater CR-300. The results are shown in Table 3.

Table 4

division L value Example 1 83 Example 2 85 Comparative Example 1 76

Claims (10)

A step of producing a polymerization solvent; Dissolving aromatic diamine in the polymerization solvent to prepare a mixed solution; And Adding an aromatic dieside halide to the mixed solution to polymerize the aromatic diamine and an aromatic dieside halide, In this case, the polymerization solvent is a method for producing an aromatic polyamide polymer, characterized in that the visible light transmittance of 70% or more. The method of claim 1, The process for producing a polymerization solvent having a visible light transmittance of 70% or more comprises the step of adjusting the content of Fe contained as impurities in the polymerization solvent to 5ppm or less. The method of claim 1, The step of preparing a polymerization solvent having a visible light transmittance of 70% or more comprises the step of adding calcium chloride, an inorganic salt, to N-methyl-2-pyrrolidone (NMP), an organic solvent, wherein the calcium chloride is contained in the calcium chloride. Method for producing an aromatic polyamide polymer, characterized in that the content of Fe is 5ppm or less. The method of claim 1, The polymer obtained through the above process has an L value of 60 or more. Preparing an aromatic polyamide polymer having an L value of 60 or more; Dissolving the aromatic polyamide polymer in a solvent to prepare a radial dope; And And radiating the radiation dope. The method of claim 5, The process for producing an aromatic polyamide polymer having an L value of 60 or more includes a step of polymerizing an aromatic diamine and an aromatic dieside halide in a polymerization solvent having a visible light transmittance of 70% or more. Manufacturing method. The method according to claim 6, The polymerization solvent is a method for producing aramid fibers, characterized in that the Fe contained less than 5ppm. The method of claim 5, The aramid fiber obtained through the process is a method for producing aramid fiber, characterized in that it has an L value of 80 or more. Aramid fibers comprising benzene rings connected linearly through an amide group (CONH), having an L value of 80 or more. 10. The method of claim 9, The aramid fiber is an aramid fiber, characterized in that produced by spinning an aromatic polyamide polymer having an L value of 60 or more obtained by polymerizing an aromatic diamine and an aromatic dieside halide in a polymerization solvent having a visible light transmittance of 70% or more.