JPH0284509A - Production of polybenzthizaole fiber, polybenzoxazole fiber or polybenzimidazole fiber - Google Patents

Abstract

PURPOSE:To provide the subject fiber having excellent stringiness by dissolving a polybenzthiazole, polybenzoxazole or polybenzimidazole in a specific solvent in a state free from any observable liquid crystal phase and subsequently spin ning the solution. CONSTITUTION:An all aromatic heterocyclic polymeric compound such as a polybenzthiazole, polybenzoxazole or polybenzimidazole is dissolved in polyphosphoric acid or methane sulfonic acid (mixture) in a low concentration free from any observed liquid crystal phase and the prepared solution is spun to provide the objective fiber having excellent stringiness and drawability.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing polybenzothiazole fibers, polybenzoxazole fibers or polybenzimidazole fibers.

Technical background of the invention and its problems In recent years, fully aromatic heterocyclic polymer compounds such as polybenzothiazoles, polybenzoxazoles, and polybenzimidazoles have attracted attention as heat-resistant resins instead of polyimide resins. has been done. Examples of such wholly aromatic heterocyclic polymer compounds include the following compounds.

Poly(P-phenylenebenzobisthiazole) (PBT
) Poly(2,6-benzothiazole) (ABPBT) Poly(P-phenylenebenzobisoxazole) (PI30) Poly(2,5-benzoxacil) (8BPBO) Poly(P-phenylenebenzobisimidazole)( F
BI) Poly(2,5(6)-benzimidazole) (ABPB
I) Such wholly aromatic heterocyclic polymer compounds have excellent heat resistance and, unlike polyimide resins, also have good hydrolysis resistance.

Since such wholly aromatic heterocyclic polymer compounds have a rigid skeletal structure as described above, they exhibit liquid crystallinity in solution. Liquid crystalline fibers can be obtained by, for example, forming the compound into a fibrous form.

That is, as described in publications such as Patent Application Publication No. 60-500538, for example, 2,5-diamino-1,4-benzenedithiol dihydrochloride, 4,6-diamino-1,3-benzenediol - Polybenzothiazoles, polybenzoxazoles, Fully aromatic heterocyclic polymer compounds such as polybenzimidazoles can be produced.

And, such a wholly aromatic heterocyclic polymer substance is
Once precipitated and separated from the reaction solvent as described above, it is difficult to dissolve it in an organic solvent again.・It is spun using a spinning method called the spinning method.

However, 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 a high concentration, the fully aromatic heterocyclic polymer compound has already formed a liquid crystal phase in the reaction solution, so the solution itself exhibits polarizing properties. When such a reaction solution is used for spinning using a dry jet/wet spinning method, a fiber having liquid crystal properties can be obtained. Although the fibers obtained in this way exhibit heat resistance equivalent to or higher than polyimide fibers,
Since such fibers are extremely brittle, they are difficult to handle, and since such fibers have low elongation, they cannot be subjected to operations such as stretching. Therefore, in the conventional technology related to fibers made of wholly aromatic heterocyclic polymer compounds as described above, the heat resistance and hydrolysis resistance of the wholly aromatic heterocyclic polymer compounds as described above are There was a problem that the excellent characteristics could not be effectively utilized.

OBJECT OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above.
The object of the present invention is to provide a method by which fibers having excellent spinnability and drawability can be produced from polybenzoxazoles or polybenzimidazoles.

Summary of the Invention The method for producing polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers according to the present invention includes adding polyphosphoric acid, methanesulfonic acid, or a mixture thereof to polybenzothiazole, polybenzoxazole, or The method is characterized in that polybenzimidazoles are dissolved in a state in which no liquid crystal phase is observed, and the resulting solution is spun.

According to the production method of the present invention, polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles are dissolved in a specific solvent at such a low concentration that no liquid crystal phase is observed, and this solvent is used for spinning. Because
Fibers with excellent spinnability and drawability are obtained.

DETAILED DESCRIPTION OF THE INVENTION The method for producing polybenzothiazole fibers, polybenzoxazole fibers or polybenzimidazole fibers of 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. PBTSABPTBSPBOlABPBOlPBI shown in
and ABPB! Examples include wholly aromatic heterocyclic polymer compounds such as. 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 using two or more types of wholly aromatic heterocyclic polymer compounds in combination, the two or more types of wholly aromatic heterocyclic polymer compounds may be synthesized individually, for example, by the method described below. A solution containing 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, 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 is 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT).
) and terephthalic acid (TA) in the presence of polyphosphoric acid.

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

Furthermore, ABPBT is 4-amino-3-mercaptobenzoic acid dihydrochloride (AMBA
) can be synthesized by reacting in the presence of polyphosphoric acid.

Furthermore, ABPBO is 3-amino-4-hydroxybenzoic acid hydrochloride (^11
^11) can be synthesized by reacting in the presence of polyphosphoric acid.

Furthermore, PBI, ABPBf, 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) is generally expressed by the following formula % Formula % The above polyphosphoric acid is orthophosphoric acid (H3PO4
) and a method of dehydrating and condensing phosphorus pentoxide (P2
It can be prepared by adding water to O3) 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 set to 4.6-
An example will be explained in which synthesis is performed by adding diami2-1,3-dibenzenediol hydrochloride (DAR) and terephthalic acid (TA). 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 (TA) is added to polyphosphoric acid (PPA), as shown in the following formula, TA and PPA are added, and then such tibia fluid is further heated while stirring in an inert gas stream. The reaction temperature in this case is usually 80
~100°C, and furthermore, this reaction
Once reacted at a temperature in the range of 180 -
Preferably, the reaction is carried out at a temperature in the range of 200°C.

By conducting the reaction in this manner, the concentration of the reaction solution 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 is usually 2 to 2.
It is possible to obtain a wholly aromatic heterocyclic polymer compound within the range of 50 dD/g.

By carrying out the reaction as described above, the concentration of the wholly aromatic heterocyclic polymer compound in the reaction solution is usually 5 to 20% by weight.

In a PPA solution of a wholly aromatic heterocyclic polymer compound having the above concentration, the solution itself exhibits orthogonal Nicol polarization because the wholly aromatic heterocyclic polymer compound forms a liquid crystal phase in the solution.

Liquid crystalline fibers can be obtained by spinning a reaction solution that exhibits liquid crystallinity as it is, but such a reaction solution has poor spinnability and the resulting liquid crystalline fibers are extremely brittle. Therefore, continuous spinning is difficult. Therefore, it is very difficult to utilize the excellent properties of this liquid crystal fiber, such as heat resistance and hydrolysis resistance.

In the method for producing fibers according to the present invention, a wholly aromatic heterocyclic compound such as polybenzothiazoles, polybenzooxazoles, and polybenzimidazoles is added to the above-mentioned polyphosphoric acid, methanesulfonic acid, sulfuric acid, or a mixture thereof. Spinning is performed using a solution in which a polymer compound is dissolved in a state in which no liquid crystal phase is observed.

That is, the wholly aromatic heterocyclic polymer compound produced by the above-mentioned reaction is usually diluted with the same solvent as the reaction solvent to a concentration at which no liquid crystal phase is observed after the reaction is completed. This concentration varies depending on the type and degree of polymerization of the wholly aromatic heterocyclic polymer compound used, but usually PPA
With respect to 100 parts by weight of the solvent, the wholly aromatic heterocyclic polymer compound is present in an amount of 5 parts by weight or less, preferably 0.11 to 3 parts by weight or less.

The dilution solvent used to bring the solution to the above concentration may be the same as or different from the reaction solvent. Therefore, in the present invention, the reaction solution obtained as described above is diluted with polyphosphoric acid, methane, etc. It can be diluted with sulfonic acid and/or sulfuric acid. Furthermore, in addition to the above-mentioned polyphosphoric acid, methanesulfonic acid, and sulfuric acid, chlorosulfuric acid,
Polar solvents such as trifluorosulfuric acid can also be used.

In a solution having the above concentration, the wholly aromatic heterocyclic polymer compound does not form a liquid crystal phase, so that no crossed Nicol polarization is observed.

Such a solution is spun using, for example, a dry jet/wet spinning method.

FIG. 1 schematically shows a spinning apparatus employed in the fiber manufacturing method of the present invention.

As shown in FIG. 1, the spinning apparatus that can be used in the present invention includes a container 1 filled with a PPA solution of a wholly aromatic heterocyclic polymer compound, and a gear pump 2 for discharging this solution. The spinneret mold 3 includes a spinneret mold 3, a coagulation bath 4 that coagulates the discharged material discharged from the discharge spout mold 3, and a winding device 5. Then, the yarn discharged from the spinneret mold 3 is led to a coagulation bath 4 via an air layer, and then wound up by a winding device 5.

In the present invention, when the dry jet wet spinning method as described above is adopted, the spinning is performed at a spinning temperature of usually 20 to 160°C, using a normal spinning nozzle of about 50 to 500 μm, and a draft ratio of 1. Set it to .0 or higher. Note that in order to perform spinning at the draft ratio as described above, it is possible to mechanically apply tension to the discharged yarn so that the draft ratio is as described above, but it is also possible to mechanically apply tension to the discharged yarn so that the draft ratio is as described above. By placing the yarn into a coagulation bath, drafts are generated due to the weight of the discharged yarn.
Spinning can be carried out at the above draft ratio by adjusting the discharge amount, for example, without applying mechanical tension.

In the present invention, it is preferable to use a water bath as the coagulation bath 4 in which the discharged yarn spun as described above is immersed.

That is, by leaving the discharge thread in water and removing polyphosphoric acid, methanesulfonic acid, or sulfuric acid in this way, the polymer precipitates as the residual rate of polyphosphoric acid, methanesulfonic acid, or sulfuric acid decreases. It is possible to obtain fibers that are mainly formed into a network structure and have a high degree of extensibility.

In this case, the residual rate of phosphoric acid, methanesulfonic acid or sulfuric acid in the fiber is usually 0.1% by weight or less, preferably 0.
, 01% by weight or less.

FIG. 2 shows the relationship between the time for which the discharged yarn was left in water and the strain rate versus stress of the fiber obtained by drying the coagulated yarn obtained by leaving it in water in this manner.

As is clear from FIG. 2, the elongation at break of the dried fibers obtained varies depending on the time the discharged yarn is left in water. That is, compared to drawn fibers obtained using coagulated threads that are placed in a coagulation bath and left in the coagulation bath for less than one hour, the strength of the drawn fibers obtained increases as the standing time increases. The elongation at break of the drawn fiber produced using the coagulated yarn left in the coagulation bath for 1 day (24 hours) is maximum. Then, after 24 hours, the elongation at break of the drawn fibers tends to decrease again.

FIG. 3 shows the relationship between the standing time in water and the amount of P2O5 remaining in the coagulated thread.

As shown in FIG. 3, by leaving it in water for 24 hours, for example, when PBO is used, the residual amount of polyphosphoric acid remaining in the PBO coagulated thread is 0.1% by weight or less.
Preferably it is 0.01% by weight or less.

The fibers obtained in this way usually have a thickness of 10 to 5
00 μm, and the elongation at break of the fibers measured by the method specified by ASTM D-3379-75 is in the range of 20 to 200%.

In particular, the fibers obtained by the method of the present invention have heat resistance equal 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.

In the present invention, drying is carried out at a drying temperature of usually 20 to 10
The drying is carried out at a temperature of 0°C and a drying time of usually 10 minutes or more.

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

The dried yarn thus obtained can be used as it is, but by further drawing it, it is possible to obtain a drawn fiber with high strength.

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.

Note that after drawing as described above, the obtained drawn fibers can also be heat set.

Effects of the Invention According to the production method of the present invention, polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles are dissolved in a specific solvent at a low concentration such that no liquid crystal phase is observed, and this solvent is used. Because the yarn is spun using
Fibers with excellent spinnability and drawability are obtained.

Therefore, by employing the fiber manufacturing method of the present invention, it is possible to obtain a fiber made of a wholly aromatic heterocyclic compound that has particularly excellent heat resistance and hydrolysis resistance.

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

Example 1 40% by weight of H3PO4 with a concentration of 85% and a concentration of 115%
A polyphosphoric acid solution (PPA solution) having a P2O5 content of 74.9% was prepared by mixing with 60% by weight of polyphosphoric acid.

88.6 g of the above PPA solution and 22.82 g of 4,6-diamy2-1,3-benzenediol dihandrochloride (DA) dissolved in 200 ml of resin ketone.
R) was mixed. After stirring this mixture, D
Hydrogen chloride was removed from AR.

Then, 17.96 g of terephthalic acid (
TA) was added and further 61.2 g of P 2 O was added to bring the content of P 2 O, in the mixture to 87.2% by weight.

The mixture obtained above was stirred at 100° C. for 15 hours using an oil bath under an argon stream.

By stirring under heating as described above, no significant increase in the bulk viscosity of the liquid mixture was observed.

Then, while stirring the mixture vigorously, the temperature of the oil bath was brought from 100°C to 178°C within 40 minutes, maintained at this temperature for 25 hours, then increased to 185°C within 1 hour, and at this temperature. The reaction was allowed to proceed for 25 hours.

The reaction solution obtained by carrying out the reaction as described above contains poly(P-phenylenebenzoxazole) (
Since the reaction liquid contained 13.6% by weight of PBO), this reaction liquid formed a liquid crystal phase and exhibited polarizing properties.

PPA prepared during the reaction was added to 145.0 g of this reaction solution.
By adding 794.0 g of the solution and stirring sufficiently, polarized light was no longer observed.

The P8O6 degree in this solution is 2.1 m! It was 6 kg. Intrinsic viscosity: -11.1 dR/g (30°C methanesulfonic acid) The solution obtained above was spun using a gear pump type liquid crystal spinning device (spinning projection diameter 360 μm, 1 hole) at a spinning temperature of 135°C and a discharge rate. After discharging into the air with an air gap of 3.5 cm under the conditions of 9.6 ml/min and a draft ratio of 1, it was spun into a coagulation bath containing a large amount of water (discharged yarn).

The discharged yarn spun as described above was placed in water at 25° C. and left in water for 24 hours.

By leaving the yarn in water in this manner, the P2O5a degree in the discharged yarn decreased to 0.0074% by weight.

The elongation at break of this fiber when evaluated in the wet state is 90%.
Met.

After reducing the P2O5a degree as described above, it was taken out from water and dried at 80°C for 12 hours to obtain a dry thread. The moisture content of this dry yarn was 0.01% by weight or less.

The diameter of the obtained fibers was 120 μm, and it was found that the inside of the fibers formed a network structure consisting of portions where many precipitated particles aggregated and many voids.

Furthermore, the elongation at break of this fiber was 140%.

As described above, the fibers obtained by the method of the present invention have extremely high drawability, and it was possible to obtain drawn fibers by drawing such fibers.

Examples 2-16 In Example 1, PB in PPA solution of PBO
Fibers were obtained in the same manner except that the O concentration, the draft ratio, and the time for which the discharged yarn was allowed to stand in water were changed as shown in Table 1. Note that when the solutions having the concentrations listed in Table 1 were observed, they did not have liquid crystallinity.

Various physical properties of the obtained fibers are also listed in Table 1.

Comparative Example 1 Fibers were obtained in the same manner as in Example 1, except that the reaction solution used to synthesize PBO was used as it was for spinning. The concentration of this solution was 1366% by weight, and it exhibited polarizing properties.

The obtained fibers were liquid crystalline fibers, which were extremely brittle and therefore very difficult to handle, and furthermore, such fibers could not be drawn.

Comparative Example 2 Fibers were obtained in the same manner as in Example 1, except that the time the discharged yarn was left in water was changed to 1 hour.

The P2O5a degree of this discharged yarn was 24.3% by weight. In addition, the elongation at break of the fiber in wet and dry conditions was 60%.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a spinning apparatus employed in the fiber manufacturing method of the present invention. 1... Container, 2... Gear pump, 3... Spinneret type, 4... Coagulation bath, 5... Winding device Figure 2 shows the standing time in the coagulation bath and the resulting dryness. It is a strain rate-stress curve showing the relationship between fiber elongation at break. Figure 3 shows the time the discharged thread was left in water and the P2O in the coagulated thread.
5 is a graph showing the relationship with the residual amount of No. 5. agent

Claims (1)

[Claims] (1) A method characterized by dissolving polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles in polyphosphoric acid, methanesulfonic acid, or a mixture thereof in a state in which no liquid crystal phase is observed, and spinning the resulting solution. A method for producing polybenzothiazole fiber, polybenzoxazole fiber or polybenzimidazole fiber.