JPH0874122A - Production of meta-aromatic polyamide fiber - Google Patents

Abstract

PURPOSE: To provide a method for producing a meta-aromatic polyamide fiber, capable of easily producing the fiber by a wet-spinning method from the solution (dope) of the meta-aromatic polyamide polymerized in a polar amide solvent and neutralized, and capable of imparting excellent physical properties to the fiber. CONSTITUTION: This method for producing the meta-aromatic polyamide fiber comprises neutralizing a polymer solution obtained by the reaction of an aromatic diamine with an aromatic dicarboxylic acid chloride in a polar amide solvent with an inorganic alkali, controlling the concentration of the polymer contained in the produced dope to 10-17wt.%, further controlling the water content in the dope to 30-80wt.% based on the polymer, spinning the dope into a coagulating bath, washing the spun fiber with water, and subsequently drawing the washed fiber in a drawing ratio of >=3 times. The excellent spinnability of the dope can be obtained by the use of the most usual aqueous coagulating bath as a coagulating bath, and the excellent drawing property can also be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved process for producing meta-type aromatic polyamide fibers, and more particularly, to improving the spinnability and the drawability of wet spinning to achieve excellent productivity.

[0002]

2. Description of the Related Art Meta-type aromatic polyamide fibers have excellent heat resistance and dimensional stability because their molecular skeletons are mostly composed of aromatic rings. This fiber is suitable for industrial applications and general applications where heat resistance, flame resistance and flame resistance are important. However, the method for producing meta-type aromatic polyamide fiber is not always easy. When an aromatic diamine and an aromatic dicarboxylic acid chloride are reacted and polymerized in a polar amide organic solvent, hydrochloric acid is generated as a by-product,
It is necessary to neutralize this with an inorganic alkali to convert it into a neutral inorganic salt and water. Calcium hydroxide is usually used as the inorganic alkali, and the inorganic salt after neutralization is calcium chloride. Calcium chloride is not precipitated and is dissolved in a polar amide solvent and improves the solubility of the polymer, but on the other hand, the spinnability of wet spinning is significantly reduced. When normal wet spinning is performed, the yarn is easily broken, and many microvoids are generated in the yarn during the solidification process. In addition, the stretchability is poor and sufficient fiber strength and fiber elongation cannot be obtained. Even if calcium oxide or lithium hydroxide is used as the inorganic alkali, the situation does not change.

Therefore, various measures have heretofore been proposed to improve the spinnability. For example, Japanese Unexamined Patent Publication No. 51-564 proposes a method of using a special coagulation bath containing polyalkylene glycol as a main component, but this method alone slows the coagulation rate and can increase the spinning speed. Can not. Further, Japanese Patent Publication No. 44-11168 describes a method of using dry spinning instead of wet spinning. However, dry spinning requires a high equipment cost and it is technical to spin a large number of filaments. It's difficult.

Wet spinning of meta-type aromatic polyamide fibers is difficult because when the coagulant penetrates into the yarn, microvoids are generated and the yarn devitrifies and becomes brittle. The more neutral salts such as calcium chloride in the dope, the more the devitrification and the embrittlement are promoted. This tendency is severe when water is used as a coagulant. In the past, in order to delay the invasion of this water, inorganic salts were added to the coagulation liquid and various other measures were made, but these have not been successful.
As a result of diligently studying the spinning principle of the meta-type aromatic polyamide fiber, we reversed the idea of avoiding water, and by incorporating a large amount of water in the dope beforehand, the spinnability, drawability and fiber physical properties were improved. The present invention was found to be significantly improved.

[0005]

An object of the present invention is to easily form a solution (dope) of a meta-type aromatic polyamide polymerized in a polar amide solvent and neutralized by wet spinning as it is, and to obtain excellent physical properties. It is to provide a manufacturing method for imparting. In particular, it is to obtain excellent spinnability in an aqueous coagulation bath, which is the most common coagulation bath, and to achieve excellent drawability.

[0006]

According to the present invention, "(Claim 1) An inorganic alkali is added to a polymer solution obtained by reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in a polar amide solvent to neutralize the polymer solution. The concentration of the polymer contained in the prepared dope is adjusted to 10 to 17% by weight, and the water content in the dope is adjusted to 30 to 80% by weight relative to the polymer,
A method for producing a meta-type aromatic polyamide fiber, which comprises subjecting the dope to wet spinning in a coagulation bath, followed by washing with water and stretching at a draw ratio of 3 times or more. (Claim 2) The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein 85 mol% or more of the repeating unit of the meta-type aromatic polyamide comprises the following repeating unit (Chemical Formula 2).

[0007]

Embedded image

(Claim 3) The method for producing meta-type aromatic polyamide fiber according to claim 1, wherein the polymer concentration in the dope is 12 to 15% by weight. (Claim 4) The polar amide solvent is N-methyl-2.
-The method for producing a meta-type aromatic polyamide fiber according to claim 1, which is pyrrolidone or dimethylacetamide. (Claim 5) The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is an aqueous solution of an inorganic salt. (Claim 6) The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is polyalkylene glycol. (Claim 7) The method for producing meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is a mixture of water and the polar amide solvent. (Claim 8) The method for producing meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is a mixture of water and the polar amide solvent. It is.

The present invention will be described in detail below. The meta-type aromatic polyamide fiber of the present invention is a poly-m-phenylene isophthalamide fiber substantially composed of the following repeating unit (Chemical Formula 3). A copolymer containing less than 15 mol% of the third component may be used. Further, the meta-type aromatic polyamide may contain less than 10% by weight of an inactive pigment or a twisting agent.

[0010]

[Chemical 3]

The main raw materials used in the present invention are m-phenylenediamine as the aromatic diamine and isophthalic acid chloride as the aromatic dicarboxylic acid chloride, which are dissolved in a polar amide solvent and reacted to give poly-m.
-Phenylene isophthalamide is obtained. As the degree of polymerization, the intrinsic viscosity [η] is preferably 1.0 to 2.5, and particularly 1.3 to 2.2 for fibers.

The inorganic alkali for neutralizing the hydrochloric acid generated by the polymerization is preferably calcium hydroxide, calcium oxide or lithium hydroxide. The inorganic alkali may be added as a solid fine powder as it is, but more uniform neutralization is possible by adding it as a slurry in a polar amide solvent used during polymerization. When calcium hydroxide is used, 46.6% by weight of calcium chloride and 15.1% by weight of water are generated with respect to the polymer. Therefore, in order to satisfy the conditions of the present invention, it is necessary to add more water. When water is added to the dope, the dissolved polymer gels if water is applied rapidly, so it is preferable to add it little by little or to add a mixture of the solvent used during polymerization and water. By this operation, the water in the dope is added to the polymer in an amount of 30-80
Adjust to weight%. The effect of water is to improve the plasticity of the dope, especially the deformability to the draft immediately after exiting the spinning hole, and to mitigate the rapid concentration change of water and solvent when water enters from the coagulation bath side. , Seems to suppress the generation of microvoids. If the amount of water is less than 30% by weight, this effect is insufficient and single yarn breakage during spinning and devitrification due to microvoids are not improved. If the amount of water exceeds 80% by weight, the stability of the dope itself is lowered and gelation occurs to make spinning impossible.

The polymer concentration in the dope is also important. In the case of spinning a general meta-type aromatic polyamide, a suitable spinnability can be obtained at a polymer concentration of 18% by weight or more, but in the present invention, the polymer concentration must be lower than this. It is considered that this is because the suitable spinning area was changed from the conventional common sense due to the interaction between the water content and the polymer concentration. Polymer concentration is 1
If it exceeds 8%, the spinnability in a water-based coagulation bath is significantly reduced. On the contrary, when the polymer concentration is less than 10% by weight, the viscosity of the dope becomes too low and the spun yarns come into contact with each other to cause single yarn breakage or adhesion. A polymer concentration range of 12 to 15% by weight is especially preferred.

The polar amide solvent used in the polymerization of the present invention is preferably a good solvent such as N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) or dimethylacetamide (hereinafter abbreviated as DMAC).

The present invention can exert remarkable effects in an aqueous coagulation bath. When the meta-type aromatic polyamide is spun into an aqueous coagulation bath, the solvent and water are exchanged rapidly,
Although microvoids are generated and the yarn formability is lowered and the yarn is apt to deteriorate, spinning by the method of the present invention remarkably improves the yarn formability and fiber physical properties. In a water-based coagulation bath, a chlorine-based inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, zinc chloride, aluminum chloride, tin chloride, iron chloride, sodium chloride, or a nitrate such as aluminum nitrate, calcium nitrate, zinc nitrate, or Mixing with rhodanic salt can further delay the intrusion of water into the yarn,
The effects of the present invention can be maximized.

The effects of the present invention can be obtained even in a coagulation bath whose main component is polyalkylene glycol. Polyalkylene glycol itself has a small coagulation ability, but when it is wet spun in the range of the polymer concentration and the water content defined in the present invention, sufficient spinnability can be obtained even at a high spinning speed. The polyalkylene glycol used in the present invention is substantially
Polyethylene glycol, polypropylene glycol, or copolymers or mixtures thereof. 15% by weight
The following third component may be copolymerized or mixed.

In the present invention, after the dope is spun,
Coagulation is performed until the concentration of the solvent contained in the yarn is 200% by weight or less based on the polymer. If the solvent concentration exceeds 200% by weight, the yarn is soft and difficult to handle by washing with water, and devitrification easily occurs. Then, washing with water and stretching are performed.
Stretching may be performed after the solvent contained in the yarn is almost completely removed by washing with water, or stretching may be performed partially in parallel during washing with water. Stretching is performed twice or more during washing with water or while the washed yarn is wet. When this yarn is dried and subjected to a fixed length heat treatment under heating or further drawing, it is possible to finish the fiber with good process tone and excellent physical properties. The total draw ratio must be 3 times or more. Draw ratio is 3
If it is less than double, it is difficult to obtain a fiber strength of 4 g / de or more. In the present invention, it is preferably about 3.5 to 5 times.

The spinning apparatus used in the present invention may be based on a known wet spinning method. So-called dry jet wet spinning in which a gap is provided between the spinneret and the coagulating liquid may be used. The number of spinning holes may be a filament type of 10 to 1000, and the number of spinning holes is 1000 to 30000.
You can also use a single type. Spinning hole diameter is 0.05-0.2
mm is commonly used. The spinning speed is 5 to 50 m / min, and the spinning condition is stable. Even higher spinning speeds are possible if the coagulated yarn is accelerated by the fluidized coagulation bath. As the stretching equipment, a hot water stretching bath at 60 to 99 ° C., and a hot plate, a heating roll or a non-contact type heater for performing constant length heat treatment or dry heat stretching after the hot water stretching are used. These heating temperatures are 250-400 degreeC.

[0019]

As described above, according to the present invention, the dope concentration of the meta-type aromatic polyamide is made lower than before, water is further added and adjusted, and the mixture is spun in an aqueous coagulation bath or a polyalkylene glycol coagulation bath. By performing washing with water and proper stretching, under excellent process condition that has never been obtained before,
It is possible to obtain a meta-type aromatic polyamide fiber having excellent physical properties.

The invention is described in detail in the examples below.
Each characteristic value shown in the examples was measured by the following methods.

<Intrinsic viscosity [η]> The polymer or fiber was dissolved in 97% by weight concentrated sulfuric acid, and the viscosity was measured at 30 ° C.

<Polymer Concentration> The pure polymer content in the dope is represented by% by weight based on the total weight of the dope. The polymer content can be accurately calculated stoichiometrically, or can be measured by coagulating a dope thin film with water, thoroughly washing with water, drying and weighing.

<Moisture Content> The water content of the dope is represented by% by weight with respect to the polymer.

<Strength, Elongation> The strength and elongation of the fiber are JIS
According to -1074, sample length 2cm, extension speed 2c
It was measured in m / min.

[0025]

Examples 1-3, Comparative Examples 1-4 Stirrer, nitrogen inlet,
129.8 m-phenylenediamine (MPDA) into a separable flask equipped with a calcium chloride drying tube.
Then, 1000 parts of NMP was added and MPDA was dissolved while stirring. Stirring is continued even after MPDA is dissolved, and the solution is cooled with a dry ice / acetone refrigerant.
Cooled to 20 ° C. To this solution was added 243.6 parts of powder of isophthalic acid chloride (IPC). IPC was gradually added while adjusting the addition rate so that the temperature in the flask did not exceed 10 ° C. After the total amount of IPC was added, the reaction solution temperature was raised to 50 ° C. and the reaction was continued for 1 hour.
Viscous poly-m-phenylene isophthalamide (PMI
A) A solution was obtained. To neutralize the hydrochloric acid produced as a by-product, NM
After adding a slurry containing 30% of calcium hydroxide fine particles to P, solutions in which water and NMP were mixed at various mixing ratios were gradually added to prepare dopes having various polymer concentrations and water contents. Add these dopes to 85 ℃
The mixture was heated and heated by wet spinning from a spinneret having a hole diameter of 0.06 mm and 200 holes into a coagulation bath. The composition of the coagulation bath is 40% by weight of calcium chloride, 5% by weight of NMP and 55% of the remaining water.
% By weight and the coagulation bath temperature was 98.degree. The yarn was run in a coagulation bath for about 100 cm and drawn out at a speed of 10 m / min. The yarn was washed with water, stretched 2.4 times with hot water at 85 ° C., dried with a roll at 200 ° C., and stretched 1.8 times on a hot plate at 300 ° C. to give 400 denier / 200 filaments. The drawn yarn of was obtained. The total draw ratio was 4.32. The results are summarized in Table 1.

In Comparative Example 1, the concentration of the polymer in the dope was too low, that is, 9% by weight, so that the viscosity was low, and the yarn was slackened in the coagulating bath and the running did not proceed normally. The strength of the obtained drawn yarn was low and could not be used. When the concentration was increased to 12% by weight, the running state in the coagulation bath became normal as shown in Example 1, both spinning and drawing conditions were good, and a strength of 5 g / de or more was obtained. In Example 3, the polymer concentration was 14% by weight and the water content in the dope was 50% by weight with respect to the polymer. The spinning / drawing condition was the best in this table. Moisture content is 27% by weight even if the polymer concentration is appropriate
As shown in Comparative Example 2, single yarn breakage occurred during spinning, resulting in poor process tone. On the contrary, as shown in Comparative Example 3, when the water content increased to 90% by weight, the dope was apt to gel and the long-term storage became impossible. If the polymer concentration exceeds 17% by weight, as shown in Comparative Example 4, the dope becomes too viscous, and many yarn breakages occur during spinning. The influence of the polymer concentration and the water content in the dope is also shown in Table 1.

[0027]

[Table 1]

[0028]

Examples 4 to 6 and Comparative Example 5 Using the same dope as in Example 3, the changes in the physical properties of the drawn yarn were investigated by changing the draw ratio in hot water and draw ratio of the hot plate. The examination results (Example 4) are shown in Table 2. In Comparative Example 5, after washing the yarn with water,
It is stretched 2.7 times in warm water and then 1.1 at 300 ° C on a hot plate.
This is an example in which the drawn yarn is doubled, but the strength of the obtained drawn yarn is low and the fiber has no utility value. When the draw ratio in warm water was raised to 3.4 and the film was drawn 1.1 times on a hot plate, Example 5
As shown in (1), a drawn yarn having no practical problem was obtained. Example 6 is an example in which after stretching 2.7 times in warm water and then stretching 1.8 times on a hot plate to give a total stretching ratio of 4.86, the strength is higher than 6 g / de. A strong fiber was obtained.
Here, regarding the influence of the draw ratio (polymer concentration 14% by weight, moisture content 50%, hot water 85 ° C., hot plate 300 ° C.), Table 2
It was shown to.

[0029]

[Table 2]

[0030]

[Examples 7 to 10] Dopes were prepared in the same manner as in Example 3, and the spinning process was performed by changing the components of the coagulation bath. The other spinning conditions were the same as in Example 3. Table 3 shows the results. Example 7 is an aqueous solution of zinc chloride as a coagulating bath, Example 8 is an aqueous solution of zinc nitrate, and Example 9 is a rhodanate (Ca).
In this example, an aqueous solution of (SCN) ₂ ) was used, but spinning and drawing were performed in the same manner as in Example 3 to obtain good yarn quality and process tone. Example 10 is an example in which polyethylene glycol having a purity of 98% or more was used as a coagulation bath, but good fiber properties were obtained although the coagulation rate was relatively slow. Table 3 shows the relationship between the coagulation bath composition, the yarn physical properties, and the process condition.

[0031]

[Table 3]

[0032]

Example 11 The polymer concentration was 12 as in Example 2 above.
% Dope was created. This dope is supplied at 30 ° C.,
From a spinning hole with a hole diameter of 0.05 mm, extruded into a first coagulation bath of an aqueous solution of 5% NMP concentration of 2% and immersed for 3 seconds, and then transferred to a second coagulation bath of an aqueous calcium chloride solution of 95% temperature of 42%. Then, the solidification was completed and it was pulled up at a speed of 20 m / min. Then, after washing with cold water at 5 ° C, 85
It was drawn 2.8 times with hot water at ℃, and 1. on a hot plate at 350 ℃.
It was stretched 8 times. Good process condition, strength 4.7g / d
e, a drawn yarn having an elongation of 62% was obtained.

[0033]

[Example 12] As in Example 1, 129.8 parts of MPDA was put into a separable flask equipped with a stirrer, a nitrogen inlet, and a drying tube of calcium chloride, and then 1000 parts of DMAC was added this time. The MPDA was dissolved with stirring. After the MPDA was dissolved, stirring was continued, and the solution was cooled to -20 ° C with a dry ice / acetone refrigerant. 243.6 parts of IPC powder was added to this solution. IPC was gradually added while adjusting the addition rate so that the temperature in the flask did not exceed 10 ° C. After the total amount of IPC was added, the reaction solution temperature was heated to 50 ° C. and the reaction was continued for 1 hour to obtain a viscous poly-m-phenylene isophthalamide (PMIA) solution. To neutralize the by-produced hydrochloric acid, 30% of calcium hydroxide fine particles are added to DMAC.
After the contained slurry was added, a solution in which water and DMAC were mixed at various mixing ratios was gradually added to prepare a dope having a polymer concentration of 16% and a water content of 50%.

The dope was heated to 85 ° C. and the pore size was 0.0
Wet spinning was performed from a spinneret having a diameter of 6 mm and a number of holes of 200 into a coagulation bath. The composition of the coagulation bath is 40% by weight of calcium chloride, D
The MAC was 5% by weight, the remaining water was 55% by weight, and the temperature of the coagulation bath was 98 ° C. About 10 threads are in the coagulation bath
It was run for 0 cm and pulled out at a speed of 10 m / min. The yarn is washed with water and stretched 2.4 times with warm water at 85 ° C.
It was dried with a roll at 0 ° C. and then drawn 1.8 times on a hot plate of 300 ° C. to obtain a drawn yarn of 400 de / 200 filament. The total draw ratio was 4.32. There is no problem with the process condition, the physical properties of the drawn yarn are good, and the strength is 5.2 g /
The de and the elongation were 58%.

Claims (8)

[Claims] 1. A dope prepared by reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in a polar amide-based solvent with an inorganic alkali to neutralize the polymer contained in the dope. 10 to 17% by weight,
Further, the water content in the dope is adjusted to be 30 to 80% by weight relative to the polymer, the dope is wet-spun in a coagulation bath, followed by washing with water and stretching at a draw ratio of 3 times or more. A method for producing a meta-type aromatic polyamide fiber. 2. The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein 85 mol% or more of the repeating units of the meta-type aromatic polyamide comprises the following repeating unit (Chemical Formula 1). Embedded image 3. The method for producing meta-type aromatic polyamide fiber according to claim 1, wherein the polymer concentration in the dope is 12 to 15% by weight. 4. The polar amide solvent is N-methyl-2-
The method for producing a meta-type aromatic polyamide fiber according to claim 1, which is pyrrolidone. 5. The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein the polar amide solvent is dimethylacetamide. 6. The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is an aqueous solution of an inorganic salt. 7. The method for producing a meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is polyalkylene glycol. 8. The method for producing meta-type aromatic polyamide fiber according to claim 1, wherein the main component of the coagulation bath is a mixture of water and the polar amide solvent.