JPH03104920A - Production of fiber of polybenzothiazoles, polybenzoxazoles or polybenzimidazoles - Google Patents

Abstract

PURPOSE:To obtain fiber of polybenzothiazoles, etc., excellent in flex fatigue, heat and hydrolytic resistance by dissolving the polybenzothiazoles, etc., in polyphosphoric acid, etc., discharging and spinning the resultant specific solution into a coagulation bath. CONSTITUTION:Polybenzothiazoles, polybenzoxazoles or polybenzimidazoles are dissolved in polyphosphoric acid, methanesulfonic acid, sulfuric acid or a mixture thereof and the resultant solution in 1-50wt.%, preferably 2-20wt.% concentration having 5X10<2> to 5X10<6>P viscosity is subsequently discharged and spun into a coagulation bath (preferably water bath) at 5X10<2> to 5X10<4>cm/ sec, preferably 10<3> to 2X10<4>cm/sec average flow velocity and then subjected to treatment, such as preferably drying, heat-treating and drawing, to afford fiber of the polybenzothiazoles, polybenzoxazoles or polybenzimidazoles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polybenzothiazole fibers, polybenzoxazole fibers or polybenzimidazole fibers having excellent bending fatigue resistance.

Technical Background of the Invention In recent years, fully aromatic heterocyclic polymer compounds such as polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles have attracted attention as heat-resistant resins in place of polyimide resins. Examples of such wholly aromatic heterocyclic polymer compounds include the following compounds.

Poly(p-phenylenebenzobisthiazole) (PBT
) Poly(2,6-penzothiazole) ( A B P
B T) Poly(P-phenylenebenzobisoxazole) (PBO) Poly(2,5-penzoxazole) (ABP8
0) Boli(P-phenylenebenzobisimidazole) (
FBI) Poly(2.5 (6)-benzimidazole)
(AIIPBI) Such a wholly aromatic heterocyclic polymer compound has excellent heat resistance and, as is already known, unlike polyimide resins, it also has extremely excellent hydrolysis resistance.

A wholly aromatic heterocyclic polymer compound having such a rigid skeleton structure exhibits liquid crystallinity in solution when a suitable solvent is used. By spinning such a liquid crystal solution, a liquid crystal fiber made of a wholly aromatic heterocyclic polymer compound having characteristics of a liquid crystal structure can be obtained.

For example, 2,5-diamino-1,4-benzenedithiol,
Dihydrochloride, 46-diamino-13-benzenediol dihydrochloride or 124.5
- By polymerizing tetraaminobenzene, tetrahydrochloride, etc. and terephthalic acid using a reaction solvent such as polyphosphoric acid, fully aromatic heterocyclics such as polybenzothiazoles, polybenzoxazoles, and polybenzimidazoles are produced. It is described that polymer compounds can be produced.

When such a wholly aromatic heterocyclic polymer compound is precipitated and separated from the reaction solvent as described above,
Since it is difficult to redissolve in an organic solvent, the reaction solution obtained by performing the reaction as described above can be used as it is or diluted as a spinning stock solution by wet spinning method (wet spinning method) or dry jet/ wet·
It is spun using a spinning method called the wet-dry spinning method.

By the way, such a reaction solution contains fully aromatic heterocyclic polymer compounds such as polybenzothiazoles, polybenzoxazoles, and polybenzimidazoles, usually at a high concentration of 5 to 20% by weight. At such high concentrations, fully aromatic heterocyclic polymer compounds may already form a liquid crystal phase in the reaction solution, in which case polarized light is observed in the solution under crossed Nicols conditions. Ru. Furthermore, even if they do not form a liquid crystal phase, these polymer compounds are highly agglomerated with each other and form a certain type of domain structure. When such a reaction solution is spun using a wet spinning method or a dry jet/wet spinning method, it is possible to obtain a product that has almost the same liquid crystal or similar structure. fibers are obtained. However, although the fibers obtained in this way have heat resistance equivalent to or higher than polyimide fibers, they are extremely brittle and cannot be stretched due to their low elongation. There was a problem with poor workability. Therefore, in the conventional technology related to fibers made of wholly aromatic heterocyclic polymer compounds as described above, it is difficult to utilize the excellent properties such as heat resistance and hydrolysis resistance of wholly aromatic heterocyclic polymer compounds. could not be used effectively.

Purpose of the Invention The present invention aims to solve the problems of the prior art, that is, brittleness, as described above, and to obtain a fiber with excellent toughness. , polybenzoxazole fibers, and polybenzimidazole fibers.

Summary of the Invention The method for producing polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers with excellent bending fatigue resistance according to the present invention includes polyphosphoric acid,
Polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles are dissolved in methanesulfonic acid, sulfuric acid, or a mixture thereof to a concentration of 1 to 50% by weight, and the viscosity of the resulting solution is adjusted to 5×1.
02~5X106 poise, and the average flow rate of this solution was 5X.
It is characterized in that it is passed through a nozzle and discharged into a coagulation bath for spinning at a rate of 102 to 5 x 104 ao/leC.

According to the manufacturing method of the present invention, polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers having excellent bending fatigue resistance can be obtained.

DETAILED DESCRIPTION OF THE INVENTION The method for producing polybenzothiazole fibers, polybenzoxazole fibers or polybenzimidazole fibers having excellent bending fatigue resistance according to the present invention will be specifically described below.

The polymer compounds used in the method for producing fibers according to the present invention are polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles, and specifically, such polymer compounds include those of the above formula. The PBT shown in ABPBTSPBOSABPBO, FB
Fully aromatic heterocyclic macromolecular compounds such as ABPB 1 and ABPB 1 can be mentioned. In addition, in the present invention, the above-mentioned wholly aromatic heterocyclic polymer compounds can be used alone, or two or more types can be used in combination. When two or more types of wholly aromatic heterocyclic polymer compounds are used in combination, the two or more types of wholly aromatic heterocyclic polymer compounds are individually combined, for example, by the method described below. Two or more types of wholly aromatic heterocyclic polymer compounds can be obtained by mixing the obtained reaction solutions and further diluting them. Apart from this, the desired results can also be obtained in a wholly aromatic heterocyclic polymer copolymer compound using two or more types of comonomers.

Among such wholly aromatic heterocyclic polymer compounds, for example, the above-mentioned PBT combines 2,5-diamino 14-benzenezothiol dihydrochloride (DABDT) and terephthalic acid (TA) with polyphosphoric acid. The synthesis can be carried out by reacting in the presence of

Further, PBO can be synthesized by reacting 4,6-diamino-1,3-benzenediol dihydrochloride (DAR) and terephthalic acid (T) in the presence of polyphosphoric acid.

Furthermore, ABPBT is 3-amino-4-hydroxybenzoic acid hydrochloride (^HAH)
can be synthesized by reacting in the presence of polyphosphoric acid.

Furthermore, PBI, ABPBI, etc. can also be produced according to the above method.

The polyphosphoric acid used in the above reaction acts not only as a reaction solvent but also as a reaction catalyst.

Here, polyphosphoric acid (PPA) can generally be represented by the following formula.

Hn+2 Pn O3n+1 The above polyphosphoric acid is orthophosphoric acid (H3p O
4) A method of heating and dehydrating condensation of phosphorus pentoxide (
It can be prepared by adding water to P205) and then heating it.

Such polyphosphoric acid is a polymeric protonic acid and an acid anhydride, and exists in the form of a colorless, transparent, and viscous syrup at room temperature.

For example, the reaction conditions when synthesizing a wholly aromatic heterocyclic polymer compound are
, 6-diamino-1,3-benzenediol dihydrochloride (DAR) and terephthalic acid (T^) are added and combined. When DAR is added to PPA and heated at 50 to 80°C under reduced pressure for about 20 hours, hydrogen chloride is removed from DAR and PPA is added to DAR as shown in the following formula.

Further, when terephthalic acid (TAI) is added to polyphosphoric acid (PPA), an adduct of TA and PPA is generated as shown in the following formula.

Then, such a mixed solution is further heated while being stirred in an inert gas stream. The reaction temperature in this case is usually 80 to 100°C, and the reaction is then further carried out.
Preferably, it is carried out at a temperature in the range of 100 to 180°C.

By carrying out the reaction in this manner, the viscosity of the reaction liquid gradually increases as the reaction progresses. That is,
By reacting under the above conditions, the intrinsic viscosity [η] measured in methanesulfonic acid at 30°C usually becomes 2.
It is possible to obtain a wholly aromatic heterocyclic polymer compound having a molecular weight within the range of ~50 dl/g.

By carrying out the reaction as described above, the concentration of the fully aromatic heterocyclic polymer compound in the reaction solution is
It is usually 2 to 50% by weight.

In a PPA solution of a wholly aromatic heterocyclic polymer compound having the above concentration, the wholly aromatic heterocyclic polymer compound forms a liquid crystal phase in the solution, and polarized light is observed under crossed Nicols. Such a reaction solution is used as it is or after being diluted for spinning. The diluent solvent may be the same as or different from the reaction solvent. Therefore, in the present invention, the reaction solution obtained as described above can be diluted with polyphosphoric acid, methanesulfonic acid and/or sulfuric acid.

Furthermore, in addition to the above-mentioned polyphosphoric acid, methanesulfonic acid, and sulfuric acid, polar solvents such as chlorosulfuric acid and trifluorosulfuric acid can also be used within a range that does not impair the properties of the solution used in the present invention.

Such a solution can be prepared by, for example, wet spinning,
Spun using dry jet/wet spinning method.

By the way, as mentioned above, in such solutions of wholly aromatic heterocyclic polymer compounds, because the polymer is rigid and strong intermolecular forces act, a special aggregation state ( For example, even if a liquid crystal state does not exhibit a liquid crystal state optically, a similar agglomeration state exists.)
It is known to take Moreover, the influence of this special aggregation state remains in the fiber after spinning and solidification. For this reason, when the above-mentioned wholly aromatic heterocyclic polymer compound is spun using conventionally known methods and conventionally known conditions, the resulting fibers are brittle, have poor bending fatigue resistance, and are easily cut. Put it away.

This is because when a solution of polymers in a special agglomerated state is spun as a spinning dope, part or all of the structure remains as a fiber structure, forming an aggregate structure of domains. When a fiber with such a structure is repeatedly bent, stress concentrates at the boundary between the domains.
It is thought that peeling or shifting occurs in this part, which becomes a starting point and easily leads to breakage.

The present invention solves these problems as follows. That is, in the present invention, polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles are added to polyphosphoric acid, methanesulfonic acid, sulfuric acid, or a mixture thereof at a concentration of 1 to 50% by weight, preferably 2 to 20% by weight. %, and the resulting solution has a viscosity of 5 x 10 to 5 x 106 boids, and the average flow rate of this solution is 5 x 10 to 5 x 104 c"/3 iec, preferably 10 to 2 x 1 0'
Polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers with excellent bending fatigue resistance are obtained by passing through an an/sec ten nozzle, discharging into a coagulation bath, and spinning.

Here, the solution viscosity is determined by the molecular weight of the polymer that is the solute, the solution concentration, the solution temperature, the solvent, etc.

Solution viscosity is related to the time required for the regular agglomeration state of polymers in the solution, which were broken or fragmented by shearing force when passing through the spinning nozzle, to re-form after passing through the nozzle, that is, the magnitude of the relaxation time. do. Therefore, in the present invention, the viscosity of the solution is set to 5 x 102 to 5 x 106 poise. When the viscosity of the solution is 5 x 102 to 5 x 106 voids, the solution has excellent fluidity and fibers with excellent bending fatigue resistance can be obtained.

The concentration of the solution is one of the factors that determines the viscosity of the solution, but it is also the most important factor that determines the density of the fibers formed. Therefore, in the present invention, the content of the above solution is 1 to 50% by weight.

When the concentration of the solution is 1 to 50% by weight, the solution has excellent fluidity and fibers with excellent mechanical strength can be obtained.

Furthermore, if the shearing force applied to the solution when passing through the nozzle is within a certain range, fibers with excellent bending fatigue resistance can be obtained.

For this reason, in the present invention, the above solution has an average flow rate of 5 x 102 ~
5 x 104 cm/..., preferably 10"~2 x 10'a
It passes through a nozzle at o/sec and is discharged into a coagulation bath for spinning.

By maintaining the average flow rate within a certain range, the aggregated structure formed in the solution can be destroyed or fragmented, and a stable fluid state can be maintained. Average flow velocity is 5X102a
o/see or less, this agglomerated structure tends to be insufficiently destroyed; on the other hand, when the average flow velocity is 5 x 104 cm/s
If it is higher than ec, the flow of the solution tends to become unstable.

As mentioned above, the above solution was heated at an average flow rate of 5×102 to 5×
By passing through a nozzle at 10' an/+ec and discharging it into a coagulation bath, the aggregated structure in the solution is destroyed or fragmented during spinning, and the aggregated structure can be solidified before it is re-formed. Fibers with excellent fatigue resistance can be obtained.

In this way, by controlling the viscosity and concentration of the spinning solution and the average flow rate during spinning within the above ranges, we can produce polybenzothiazole, polybenzoxazole, or polybenzimidazole fibers with excellent bending fatigue resistance. can be obtained.

FIG. 1 schematically shows an example of a spinning device employed in the manufacturing method of the present invention. As shown in FIG. a coagulation bath 4 that coagulates the discharged material discharged from the spinneret 3;
It consists of a winding device 15. Then, the yarn discharged from the spinneret mold 4 is guided to the coagulation bath 4 via an air layer, and then wound up by a winding device 5.

In the present invention, it is preferable to use a water bath as the coagulation bath. The thread discharged into the coagulation bath is then immersed in water to remove the solvent. The fibers obtained by the method of the present invention have heat resistance equivalent to or higher than that of polyimide fibers. Furthermore, unlike polyimide, the fibers obtained by the method of the present invention have excellent water resistance and are not hydrolyzed.

The fibers (coagulated threads) thus obtained are usually dried after being pulled out of the water. Such drying is preferably carried out by setting the drying temperature usually in the range of 20 to 100° C. and the drying time usually in the range of 1 minute or more.

By drying, the moisture content in the dried yarn (dried yarn) is usually 0.1% by weight or less, preferably 0.
．． The content is preferably 0.01% by weight or less.

The dried yarn thus obtained can be used as it is or after being heat treated, but if necessary, it is possible to obtain a drawn fiber with high strength by further drawing it.

When dry yarn is stretched as described above, the stretching ratio is usually 1 to 2.
00% range, and the stretching temperature is usually set in the range of 20 to 500°C. In addition, after drawing, the obtained drawn fibers can also be heat-set.

Effects of the Invention According to the production method of the present invention, polybenzothiazoles, polybenzoxazoles, polybenzimidazoles, etc., have a completely aromatic aroma that is particularly excellent in heat resistance and hydrolysis resistance, and has excellent bending fatigue resistance. It is possible to obtain fibers made of a heterocyclic polymer compound of the group heterocyclic polymer compound.

EXAMPLES Next, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples.

Example 1 and Comparative Example 1 Example 1 85% concentration of H PO4 with 40% by weight and concentration 3 115% polyphosphoric acid (H a P 0 4 base)
When mixed with 60% by weight, the content of P205 is 74.9%.
A polyphosphoric acid solution (PPA solution) was prepared.

88.6 g of the above PPA solution and 22.82 g of 46-
Diamino-1,3-benzenediol-dinohydrochloride (DAR) was mixed in a 200 ml resin kettle. After stirring this mixture, 50 to 8
Hydrogen chloride was removed from the DAR by heating to a temperature of 0° C. for about 20 hours. To this compound was added 17.96 g of terephthalic acid (Ding^) and an additional 61.2 g of P2
05 was added to bring the content of P20s in the mixture to 87.2% by weight. The mixture was stirred at 100° C. for 15 hours using an oil bath under a stream of argon. No significant increase in the bulk viscosity of the mixed liquid was observed by heating and stirring.

Then, while stirring the mixture vigorously, the temperature of the bath was raised from 100°C to 178°C within 4.0 minutes, maintained at this temperature for 25 hours, and then raised to 185°C within 1 hour. The reaction was carried out for 25 hours at temperature.

As described above, a reaction solution containing 13.6% by weight of poly(p-phenylenebenzobisoxazole) (PBO) was obtained.

A part of this reaction solution was taken out and the PP prepared during the reaction was
Solution A was added and thoroughly stirred to prepare a diluted solution with a PBO concentration of 3.52% by weight. This PBO has an intrinsic viscosity of 1
1. ldf/g (30°C, methanesulfonic acid).

The viscosity of the solution (90°C, shear rate...C') was 0.4 poise. This solution was spun into a coagulation bath containing a large amount of water by dry-wet spinning (air gap 1.5 cm) using an extrusion spinning device, and washed with water at 25° C. for 24 hours. The discharge pressure was 200 kg/a (and the average flow rate of the solution passing through the nozzle was 3.5 x l03aII/...).The P20,i!1 degree in the yarn after washing with water decreased to 0.0021% by weight. did.

The elongation at break of this fiber when evaluated in the wet state is 120%.
Met.

The fibers were taken out of the water and dried at 80° C. for 12 hours. The moisture content of the dried yarn was 0.01% by weight, and the diameter was 32 μm. A scanning electron micrograph of the surface of this dried yarn is shown in FIG. 2, and a scanning electron micrograph of the fractured surface is shown in FIG.

Comparative Example 1 In Example 1, the average flow rate of the solution was set to 1 x 102 an/
Fibers were obtained by spinning under the same conditions as in Example 1 except that sec. The P205 concentration in the thread after washing with water is 0.0021
weight%, the elongation at break of the wet fiber is 80.5%, 80
The moisture content of the yarn dried at ℃ for 12 hours is 0.01% by weight.
Met. A scanning electron micrograph of the surface of the obtained dried yarn is shown in FIG. 4, and a scanning electron micrograph of the fractured surface is shown in FIG.

The difference between Example 1 and Comparative Example 1 is the difference in the average flow rate of the solution flowing through the nozzle. Considering Figures 2 and 3,
It can be seen that the fiber surface of Example 1 has a very smooth, uniform and dense structure, although there are slight irregularities. On the other hand, the fiber surface of the comparative example has deep and sharply cut unevenness in the direction of the fiber axis, and a closer look reveals that it is composed of a collection of fine fibrils. This is because in Example 1, the agglomerated structure formed in the solution was destroyed and made fine by the high flow rate, whereas in Comparative Example 1, it was not destroyed or made fine, but was brought in as a fibrous structure. This is due to the fact that the structure of the two is clearly different.

This becomes even clearer when considering FIGS. 4 and 5, which are scanning electron micrographs of a cross section of this fiber. In Example 1, as shown in FIG. 4, the structure is very dense, and the presence of voids is hardly recognized. On the other hand, as shown in FIG. 5, Comparative Example 1 is made of a porous granular structure containing many voids, and is found to have a very coarse structure. The difference in structure between the two is clear.

Next, the bending fatigue resistance of the fibers shown in Example 1 and Comparative Example 1 was compared. For comparison, the fiber was repeatedly bent by 180° and the number of bends required to cut the fiber was measured. The number of folds of the fiber in Example 1 is 104 times or more, while the number of folds of the fiber in Comparative Example 1 is only 1.
It was 5 times.

The difference in bending fatigue resistance between the two is extremely clear.

Examples 2 to 4 and Comparative Examples 2 to 6 By the same reaction as in Example 1, a PPA solution containing 45.9% by weight of poly(p-phenylenebenzobisoxazole) (PRO) was obtained.

The PPA solution prepared during the reaction was added to this reaction solution to dilute solutions with different PBO concentrations. PBO had an intrinsic viscosity of 7.89 dl/g (30°C, methanesulfonic acid).

This solution was spun into a coagulation bath containing a large amount of water by dry-wet spinning (air gap 1.5 an) using an extrusion type spinning device, and washed with water at 25° C. for 24 hours.

The P205 concentration in the yarn after washing with water was 0.0011% by weight. This fiber was taken out of water and heated to 120℃ for 20 minutes.
Dry for a minute. The moisture content of the dried yarn was 0.01% by weight. The bending fatigue resistance of the obtained fibers was compared in the same manner as in Example ↓ and Comparative Example 1.

The results are shown in Table 1.

Table↓ *) The spinning temperature was increased to lower the solution viscosity.

Examples 5 to 7 and Comparative Examples 7 to 10 By the same reaction as in Example 1, a PPA solution containing 55.3% of poly(p-phenylenebenzobisoxazole') (PBO) was obtained.

This reaction solution was precipitated in water and thoroughly washed with water to prepare PBO powder from which PPA was completely removed.

PBO has an intrinsic viscosity = 24. 3 dl/g
(30°C, methanesulfonic acid). This PBO powder was dissolved in methanesulfonic acid and a methanesulfonic acid/PPA mixed solvent kept at 80°C to prepare a predetermined solution.

This solution was spun into a coagulation bath containing a large amount of water by dry-wet spinning (air gap 1.5 an) using an extrusion spinning device, and washed with water at 25° C. for 24 hours.

The fibers were taken out of the water and dried at 120° C. for 20 minutes. The moisture content of the dried yarn was 0.01% by weight.

The bending fatigue resistance of the obtained fibers was compared in the same manner as in Example 1 and Comparative Example 1.

The results are shown in Table 2.

Table 2 1... Container 2... Extrusion device 3... Spinneret type 4... Coagulation bath 5... Winding device Figure 2 is a scanning electron micrograph of the fiber obtained by the present invention. Figure 3 is a scanning electron micrograph of the fractured surface.

FIG. 4 is a scanning electron micrograph of the fiber obtained in the comparative example, and FIG. 5 is a scanning electron micrograph of the fractured surface thereof.

1) Methanesulfonic acid 2) The spinning temperature was increased to lower the solution viscosity.

3) Methanesulfonic acid/polyphosphoric acid = 1/1 (weight ratio) mixed solvent

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a spinning device employed in the manufacturing method according to the present invention.

Claims (1)

[Claims] (1) Dissolving polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles in polyphosphoric acid, methanesulfonic acid, sulfuric acid, or a mixture thereof to a concentration of 1 to 50% by weight, and dissolving the resulting solution. The viscosity is set to 5 x 10^2 to 5 x 10^6 poise,
Pour this solution at an average flow rate of 5 x 10^2 to 5 x 10^4 cm/
A method for producing polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers, which comprises spinning the fibers by passing them through a nozzle and discharging them into a coagulation bath at sec.