KR20090104599A - Aramid Fiber and method of making the same - Google Patents

Abstract

PURPOSE: Aramid fiber and a manufacturing method thereof are provided to increase heat treatment efficiency by performing enough plasticizing operation of a polymer chain comprising filament and performing a thermal process by applying a plasticizer. CONSTITUTION: A manufacturing method of aramid fiber includes the following steps of: manufacturing an aromatic poly amide polymer by polymerizing aromatic diamine and an aromatic family diacid halide; spinning the aromatic poly amide polymer after making the spinning dope; and heat-treating the filament gained by a spinning process. A thermal process includes a process for applying a plasticizer on the filament. In an applying process of the plasticizer, the plasticizer of 0.2 ~ 5 parts by weight is applied on the filament based on the 100 parts by weight.

Description

Aramid Fiber and Method for Making the Same

The present invention relates to aramid fibers, and more particularly to aramid fibers having a high modulus properties and a method for producing the same.

Aramid fibers include para-aramid fibers and meta-aramid fibers having a structure in which benzene rings are linearly connected through an amide group (CONH). Para-aramid fiber is 5mm thin and has a strong strength enough to lift 2 tons of cars. It is used not only for bulletproof but also for various applications in the high-tech industry of aerospace.

The aromatic polyamide fiber, collectively referred to as aramid fiber, is a step of producing an aromatic polyamide polymer by polymerizing an aromatic diamine and an aromatic dieside chloride in a polymerization solvent containing N-methyl-2-pyrrolidone, the aromatic polyamide polymer It is prepared through the process of preparing a spinning dope by dissolving in a concentrated sulfuric acid solvent, and the step of spinning the spinning dope through a spinneret and then solidifying the spinning material to produce a filament.

In addition, the obtained filaments are made of aramid fibers through a predetermined heat treatment process, and are applied to various industrial fields.

Here, the heat treatment of the filament is carried out in a state in which the filament is wound on a predetermined heat treatment roll. In the conventional case, since a large amount of moisture is contained in the filament, the temperature of the heat treatment roll decreases during the heat treatment process, thereby decreasing the heat treatment efficiency. In addition, when the temperature of the heat treatment roll is increased to solve the problem of temperature reduction of the heat treatment roll, the filament is damaged due to heat. Therefore, in the conventional case, the desired high modulus aramid fiber could not be obtained through a heat treatment process.

The present invention has been devised to solve the above conventional problem, and an object of the present invention is to provide an aramid fiber having a high modulus of elasticity by improving the heat treatment process and a method of manufacturing the same.

The present invention provides a process for preparing an aromatic polyamide polymer by polymerizing an aromatic diamine and an aromatic dieside halide to achieve the above object; Dissolving the aromatic polyamide polymer in a solvent to prepare a spinning dope and then spinning; And it comprises a step of heat-treating the filament obtained by the spinning process, wherein the heat treatment step provides a method for producing aramid fibers comprising the step of applying a plasticizer to the filament.

The process of applying a plasticizer to the filament may be made of a process of applying 0.2 to 5 parts by weight of a plasticizer with respect to 100 parts by weight of the filament.

Before the process of applying a plasticizer to the filament may be performed a step of adjusting the moisture content of the filament, wherein the step of adjusting the moisture content of the filament is 5 to 50% by weight of water based on 100 parts by weight of the filament It can be adjusted to include the addition.

The present invention provides an aramid fiber characterized in that an amide bond is bonded at least 85% between aromatic rings, and a plasticizer is contained.

The plasticizer may contain 0.1 to 2% by weight, the aramid fibers have an elastic modulus of 900 to 1200g / d.

The present invention is characterized by performing a heat treatment process by applying a plasticizer to the filament. That is, the present invention is to apply a plasticizer to the filament to perform a heat treatment process to facilitate the plasticization of the polymer chain constituting the filament during the heat treatment process so that the finally obtained aramid fibers have a high elastic modulus characteristics. It is preferable for the plasticization of the polymer chain to allow the plasticizer to be applied 0.2 to 5 parts by weight based on 100 parts by weight of the filament.

The present invention is characterized in that the process of adjusting the water content of the filament is carried out before the plasticizer is applied to the filament.

For the heat treatment step, it is preferable that the filament contains a predetermined moisture to plasticize the polymer chain constituting the filament during the heat treatment step. However, if the filament contains a large amount of water, the temperature of the heat treatment roll is reduced to cause a problem that the heat treatment efficiency is lowered. Therefore, the present invention is to control the content of the moisture contained in the filament to the extent that the temperature of the heat treatment roll is not reduced, for this purpose, the moisture content of the filament is to include 5 to 50 parts by weight of water based on 100 parts by weight of the filament It is desirable to adjust.

According to the present invention as described above has the following effects.

First, in the present invention, since the heat treatment is performed by applying a plasticizer to the filament, the plasticization of the polymer chain constituting the filament is sufficiently made to increase the heat treatment efficiency.

Second, the present invention does not reduce the heat treatment efficiency because the temperature of the heat treatment roll is not reduced because the heat treatment is performed in a state in which the content of the moisture contained in the filament is controlled. In addition, since the temperature of the heat treatment roll is not reduced, it is not necessary to increase the temperature of the heat treatment roll, thereby preventing the problem of damaging the filament due to heat.

Third, since the present invention controls the content of water contained in the filament, and performs a heat treatment process by adding a plasticizer to the filament, to achieve the desired high modulus properties by improving the crystallinity, crystal size and orientation of the finally obtained aramid fibers The aramid fiber which has is obtained.

Hereinafter, a preferred embodiment 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 the organic solvent.

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

The inorganic salt is added to increase the degree of polymerization of the aromatic polyamide, and specific examples thereof include halogenated alkali metal salts or halogenated alkaline earth metal salts such as CaCl 2, LiCl, NaCl, KCl, LiBr and KBr, and these inorganic salts. Silver may be added alone or in the form of a mixture of two or more thereof. As the amount of the inorganic salt increases, the degree of polymerization of the aromatic polyamide increases, but when the inorganic salt is added in an excessive amount, there may be an inorganic salt that does not dissolve. Thus, the inorganic salt is 10% by weight or less based on the total amount of the polymerization solvent. It is preferable that it is the range of.

2) Next, an aromatic diamine is dissolved in the prepared polymerization solvent to prepare a mixed solution.

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

 3) Next, while stirring the mixed solution, a predetermined amount of aromatic dieside halide is added to the mixed solution and prepolymerized.

In the polymerization of the aromatic diamine and the aromatic dieside halide, the reaction proceeds at a high rate with exotherm. In this way, when the polymerization rate is high, there is a problem in that the degree of polymerization differs between the finally obtained polymers. More specifically, since the polymerization reaction does not proceed simultaneously in the entire mixed solution, the polymer that has first started the polymerization proceeds rapidly to form a long molecular chain, whereas the polymer that has started the polymerization first polymerizes first. There is no choice but to form a shorter molecular chain than the polymer from which the reaction began. The higher the polymerization rate, the larger the difference. As such, when the degree of polymerization difference between the polymers finally obtained increases, physical property variations also increase, making it difficult to achieve desired characteristics.

Therefore, the prepolymerization step is to minimize the degree of polymerization between the polymers finally obtained by forming a polymer having a molecular chain of a predetermined length in advance and then performing a polymerization step.

Specific examples of the aromatic dieside halide include terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalenedicarboxylic acid dichloride or 1,5-naphthalenedicarboxylic acid dichloride, but are not necessarily It is not limited.

4) Next, after the completion of the prepolymerization step, the remaining amount of the aromatic dieside halide is added to the mixed solution while stirring at 0 ~ 30 ℃ state and polymerized.

In the production of the aromatic polyamide, since the aromatic dieside halide reacts with the aromatic diamine in a 1: 1 molar ratio, the aromatic diamine and the aromatic dieside halide may be added in the same molar ratio.

After completing the polymerization process, it is preferable to adjust the amount of aromatic diamine and dieside halide so that the concentration of the final polymer in the total polymerization solution is about 5 to 20% by weight. When the aromatic diamine and the dieside 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 must be carried out for a long time, resulting in low economic efficiency, and the aromatic diamine so that the concentration of the polymer exceeds 20% by weight. This is because when the addition dieside halide is added, the polymerization reaction does not proceed smoothly and the intrinsic viscosity of the polymer cannot be improved to 5.5 or more.

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

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

As 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 the polymerization reaction or after the polymerization reaction to generate the acid. It is to neutralize the acid.

At this time, since the aromatic polyamide obtained through the polymerization reaction is present in the form of bread crumb, the fluidity of the aromatic polyamide solution is not good. Therefore, in order to improve the fluidity, it is preferable to proceed with the subsequent process while adding water to the aromatic polyamide solution to make a slurry, and for this purpose, neutralizing by adding water together with an alkali compound to the aromatic polyamide solution during the neutralization process. The process can proceed.

The inorganic alkali compound is an alkali metal of NaOH, Li2CO3, CaCO3, LiH, CaH2, LiOH, Ca (OH) 2, Li2O or CaO, carbonate of alkaline earth metal, hydride of alkaline earth metal, hydroxide of alkaline earth metal, or oxide of alkaline earth metal It is selected from the group consisting of.

6) Next, the neutralization process is completed to grind the aromatic polyamide polymer from which the acid is removed.

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

This extraction process is most effective and economical to perform with water. The extraction process may be performed by installing a filter in a bath equipped with an outlet, placing a polymer on the filter, and then pouring water to discharge 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.

2. Aramid  Manufacture of fibers

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

The solvent may be a concentrated sulfuric acid solvent having a concentration of 97 to 100%, and chloro sulfuric acid, fluoro sulfuric acid, or the like may be used instead of concentrated sulfuric acid.

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, the polyamide polymer concentration in the spin dope preferably exceeds the above critical concentration, but the concentration is If too large, the viscosity of the spinning dope is too low occurs.

2) Next, filaments are formed by spinning the spin dope using a spinneret and then solidifying it in a coagulation bath through an air gap.

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 the bottom of the spinneret and a coagulation solution is stored therein, and a coagulation tube is formed at the bottom of the coagulation bath. Accordingly, the radiant passing through the capillary of the spinneret is solidified while sequentially descending through the air gap and the coagulating liquid to form a filament, and the filament is discharged while passing through the coagulation tube below the coagulation bath. In addition to the filament, the coagulation solution is discharged through the coagulation tube, so that the coagulation solution must be continuously supplied to the coagulation bath as much as the discharge liquid.

In addition, a jet device is formed in the coagulation tube to inject coagulation liquid into the filament passing through the coagulation tube. The injection device has a plurality of jet openings and injects the coagulating liquid toward the filaments from the plurality of injection openings. 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 spraying angle of the coagulating solution is preferably 0 to 85 ° with respect to the axial direction of the filament, and particularly 20 to 40 ° in a commercial production process.

The coagulating solution may be added sulfuric acid to water, ethylene glycol, glycerol, alcohol, or a mixture thereof, and is maintained at -20 to +90 ℃. When the radiation passed through the spinneret passes through the coagulating solution, the sulfuric acid in the emission is removed and filaments are formed. When sulfuric acid is rapidly removed from the surface, the surface is solidified before the sulfuric acid contained therein escapes. In order to solve this problem, sulfuric acid is added to form a coagulation solution.

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

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

Sulfuric acid remaining in the filament may be removed through a washing process using water or a mixed solution of water and an alkaline solution.

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

4) Next, the filament is heat treated.

The heat treatment process may be performed after controlling the moisture content of the filament and applying a plasticizer to the filament.

In the step of adjusting the water content of the filament, it is preferable to dry the filament to adjust 5 to 50 parts by weight of water based on 100 parts by weight of the filament. The water content control step of the filament can be carried out by winding the filament on a predetermined dry roll. At this time, the moisture content of the filament can be adjusted by adjusting the time that the filament is in contact with the drying roll, or by controlling the temperature of the drying roll.

In the process of applying a plasticizer to the filament, it is preferable to apply 0.2 to 5 parts by weight of a plasticizer with respect to 100 parts by weight of the filament, and the plasticizer may be used in a good compatibility with aramid fibers, among which polyhydric alcohol or An ester plasticizer can be used. Specific examples of the plasticizer include ethylene glycol, propylene glycol, polyethylene glycol, and the like. The process of applying a plasticizer to the filament may be performed by applying a plasticizer to a predetermined roll and then winding the filament on the roll to which the plasticizer is applied.

Thus, the filament coated with the plasticizer is wound around a predetermined heat treatment roll to perform a heat treatment process.

Meanwhile, a tension is applied to the filament during the spinning, washing, neutralizing, and heat treatment processes. The optimal size of the tension applied to the filament during the heat treatment process is about 3.0 to 7.0 gpd although it is determined by the overall spinning conditions. It is preferable to heat-process the filament under the tension of. If the tension is less than 3.0 gpd, the molecular orientation is reduced and ultimately the strength of the fiber is lowered. On the contrary, when the tension exceeds 7.0 gpd, there is a fear that the filament is cut, which causes manufacturing difficulties. 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 for moving the filament.

The drying rolls and the heat treatment rolls are heated by a predetermined means, and the 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 heat loss.

The aramid fiber obtained through such a heat processing process has 85% or more of amide bonds couple | bonded between aromatic rings, and the plasticizer contains a predetermined amount. The plasticizer is applied to the surface of the filament and then a large amount is vaporized during the heat treatment process, but may be contained in the aramid fibers finally penetrated into the filament obtained during the heat treatment process. At this time, the amount of the plasticizer may be contained in the total amount of the aramid fibers 0.1% by weight or more, if the content exceeds 2% by weight may reduce the physical properties of the aramid fibers. Therefore, the content of the reducing agent is preferably in the range of 0.1% to 2% by weight based on the entire aramid fiber.

The resulting aramid fibers have an elastic modulus in the range of 900 to 1200 g / d.

5) Next, the dried filament is wound on the branch pipe. The spin winding speed is preferably 300 to 800 m / min.

3. Example  And Comparative example

1) Example 1

CaCl 2 was added to N-methyl-2-pyrrolidone (NMP) to prepare a polymerization solvent, and then 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 a spinning dope. The polymer concentration in the spinning dope was adjusted to 20% by weight. Thereafter, the spinning dope was spun through a spinneret, and then passed through a 7 mm air layer and coagulated while passing through a coagulation bath containing a sulfuric acid aqueous solution and a coagulation tube below the coagulation bath to prepare a filament. While passing the coagulation tube, an aqueous sulfuric acid solution was injected into the filament through an injection device. Thereafter, the filament was washed with water to remove residual sulfuric acid.

Thereafter, the filaments were dried on a drying roll such that the water content was 5 parts by weight relative to 100 parts by weight of the filaments. Thereafter, the filament was wound around a predetermined roll coated with polyethylene glycol (molecular weight: 100). Here, polyethylene glycol corresponding to 5 parts by weight based on 100 parts by weight of the filament was to be applied to the filament. Thereafter, the filament was wound around a heat treatment roll to perform heat treatment, and then wound up to obtain aramid fibers.

2) Example 2

In Example 1 described above, the filament was dried so that the water content was 50 parts by weight with respect to 100 parts by weight of the filament, and 0.2 parts by weight of polyethylene glycol was applied to the filaments with respect to 100 parts by weight of the filament. Aramid fibers were obtained in the same manner as in Example 1.

3) Example 3

In Example 1 described above, the filament was dried so that the moisture content was 5 parts by weight based on 100 parts by weight of the filament, and 0.2 parts by weight of polyethylene glycol was applied to the filaments with respect to 100 parts by weight of the filament. Aramid fibers were obtained in the same manner as in Example 1.

4) Example 4

In Example 1 described above, the filament was dried so that the water content was 50 parts by weight based on 100 parts by weight of the filament, and 5 parts by weight of polyethylene glycol was applied to the filament with respect to 100 parts by weight of the filament. Aramid fibers were obtained in the same manner as in Example 1.

5) Comparative Example 1

In Example 1 described above, aramid by the same method as in Example 1, except that the filament having a moisture content of 100 parts by weight relative to 100 parts by weight of the filament without the addition of polyethylene glycol was wound on a heat treatment roll The fiber was obtained.

4. Experimental Example ( Aramid  Fibrous Modulus  Measure)

1) Strength measurement of aramid fiber

Each sample was prepared by cutting the aramid fibers according to Examples 1 to 4 and Comparative Example 1 to 25 cm. According to the ASTM D-885 test method, a stress-strain curve of each sample was obtained using an Instron Engineering Corp. (Instron Engineering Corp, Canton, Mass) at a tensile speed of 300 mm / min, and then a stress-strain curve. Each elastic modulus was calculated from the slope of the phase. The results are shown in Table 1 below.

division Modulus of elasticity (g / d) Example 1 950 Example 2 1010 Example 3 1050 Example 4 930 Comparative Example 1 830

Claims (11)

Polymerizing the aromatic diamine and the aromatic dieside halide to prepare an aromatic polyamide polymer; Dissolving the aromatic polyamide polymer in a solvent to prepare a spinning dope and then spinning; And It comprises a step of heat-treating the filament obtained by the spinning process, At this time, the heat treatment step is a method for producing aramid fibers, characterized in that comprises a step of applying a plasticizer to the filament. The method of claim 1, The step of applying a plasticizer to the filament is a method for producing aramid fibers, characterized in that the step of applying a plasticizer 0.2 to 5 parts by weight relative to 100 parts by weight of the filament. The method of claim 1, The step of applying the plasticizer to the filament is a method of producing aramid fibers, characterized in that the step of applying the plasticizer to a predetermined roll, the step of winding the filament on the roll coated with the plasticizer. The method of claim 1, The plasticizer is a polyhydric alcohol or ester plasticizer, characterized in that the production method of aramid fibers. The method of claim 1, A method of producing aramid fibers, characterized in that to perform a step of adjusting the moisture content of the filament before the step of applying a plasticizer to the filament. The method of claim 5, The step of adjusting the water content of the filament is a method for producing aramid fibers, characterized in that the water is adjusted to include 5 to 50 parts by weight based on 100 parts by weight of the filament. The method of claim 1, The aramid fiber is a method for producing aramid fiber, characterized in that the elastic modulus is 900 to 1200g / d. An aramid fiber characterized by having an amide bond of 85% or more bonded between the aromatic rings, and containing a plasticizer. The method of claim 8, Aramid fiber, characterized in that the plasticizer contains 0.1 to 2% by weight. The method of claim 8, The plasticizer is aramid fiber, characterized in that the polyhydric alcohol or ester plasticizer. The method of claim 8, The aramid fiber is an aramid fiber, characterized in that the elastic modulus is 900 to 1200g / d.