JPH0284510A - Production of polybenzthiazole fiber, polybenzoxazole fiber or polybenzimidazole fiber - Google Patents

Abstract

PURPOSE:To provide the subject fiber having excellent stringiness by dissolving a polybenzthiazole, etc., in a specific solvent in a state free from any observable liquid crystal phase, spinning the prepared solution and subsequently allowing the spun fiber to stand in water to control the concentration of the solvent contained in the fiber to a constant value. CONSTITUTION:An all aromatic heterocyclic polymeric compound such as a polybenzthiazole, polybenzoxazole or polybenzimidazole in polyphosphoric acid, methane sulfonic acid or sulfuric acid (mixture) in a low concentration free from any observed liquid crystal phase and the prepared solution is spun. The obtained fiber is allowed to stand in water to give a residual degree of the phosphoric acid, methane sulfonic acid or sulfuric acid in an amount of <=0.1wt.%, thereby providing 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 been used as heat-resistant resins in place of polyimide resins. Note 1. Examples of such wholly aromatic heterocyclic polymer compounds include the following compounds.

Poly(P-phenylenebenzobisthiazole) (PBT
) Poly(2,6-benzothiazole) Poly(P-phenylenebenzobisoxazole) (PB
O) Poly(2,5-benzoxacyl) (^l3PBO) Poly(P-phenylenebenzobisimidazole) (F
BI) Poly (2,5(8)-benzimidazole) (ABP
A wholly aromatic heterocyclic polymer compound such as B ricin has excellent heat resistance and, unlike polyimide resin, also has good hydrolysis resistance.

Since such a wholly aromatic heterocyclic polymer compound has a rigid skeletal structure as described above, it exhibits liquid crystallinity. A liquid crystalline fiber can be obtained by making it into a fibrous form.

That is, as described in publications such as Patent Application Publication No. Sho 60-500538, for example, 2,5-diamino-1,4-benzenedithiol dinohydrochloride, 4,6-diamitu-1,3-benzene Diol・
Dihydrochloride or t, , 2, 4,
Polybenzothiazoles,
Fully aromatic heterocyclic polymer compounds such as polybenzoxazoles and polybenzimidazoles can be produced.

And, such a wholly aromatic heterocyclic polymer substance is
Once separated by precipitation from the reaction solvent as described above, it is difficult to dissolve it in the existing solvent again. / Spun using a spinning method called wet spinning.

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 this solution itself exhibits polarizing properties. Then, using such a reaction solution,
When spinning is performed using a dry jet/wet spinning method, fibers having liquid crystal properties can be obtained. In terms of heat resistance, the fibers obtained in this way have the same or higher heat resistance than polyimide fibers, but they are extremely brittle and have the problem of being difficult to handle. . Therefore, it is said that the conventional techniques cannot effectively utilize the properties such as the excellent heat resistance and hydrolysis resistance that the wholly aromatic heterocyclic polymer compounds described above have. There was a problem.

OBJECT OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above, and provides excellent elongation at break and stretchability from polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles. It is an object of the present invention to provide a method by which fibers having strength and strength can be produced.

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, sulfuric acid, or a mixture thereof to polybenzothiazole fibers, polybenzothiazole fibers, or polybenzoimidazole fibers. Polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers obtained by dissolving oxacyls or polybenzimidazoles in a state where no liquid crystal phase is observed and spinning the solution are left in water. The fiber is characterized in that the residual percentage of phosphoric acid, methanesulfonic acid or sulfuric acid in the fiber is 0.1% by weight or less.

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. Since the fibers are left in water and the concentration of the specific solvent contained in the fibers is kept below a certain level, fibers with excellent drawability can be 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. PBT, ABPTB, PBO, ABPBO, PB shown in
Fully aromatic heterocyclic polymer compounds such as I and ABPBl 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 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, the desired effect 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, the above-mentioned PBT is, for example, 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT).
and terephthalic acid (TA) in the presence of polyphosphoric acid.

Further, 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 (AM13
^) can be synthesized by reacting in the presence of polyphosphoric acid.

Furthermore, ABPBO is 3-amino-4-hydroxybenzoic acid hydrochloride (A11
^11) can be synthesized by reacting in the presence of polyphosphoric acid.

Furthermore, PBI, ABPB 1, 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.

The reaction conditions for synthesizing the fully aromatic heterocyclic polymer compound as described above were changed to polyphosphoric acid (PPA) at 4.6
-Diami2-1,3-Benzenediol hydrochloride (DAR) and terephthalic acid (TA) are added for synthesis.

When DAR is added to PPA and heated to 50 to 80° C. under reduced pressure, hydrogen chloride is removed from DAR and PPA is added to DAR as shown in the following formula.

Next, when terephthalic acid (TA) is added to such a mixed solution, TA and PPA are added as shown in the following formula, and then this mixed solution is further heated while stirring in an inert gas stream. The reaction temperature in this case is usually 80 to 100°C.
Further, it is preferable that this reaction is carried out once at a temperature in the range of 100 to 180°C, and then subsequently reacted at a temperature in the range of 180 to 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.
A reaction solution can be obtained in which a wholly aromatic heterocyclic polymer compound within the range of 506 D/g is dissolved in the reaction solvent.

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, since the wholly aromatic heterocyclic polymer compound forms a liquid crystal phase in the solution, the solution itself receives orthogonal Nicol polarization. show.

Liquid crystal fibers can be obtained by spinning a reaction solution that exhibits liquid crystallinity as it is, but such reaction solutions have poor spinnability and the resulting liquid crystal fibers are extremely brittle. , it is difficult to carry out continuous spinning.

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 drawn fibers according to the present invention, a wholly aromatic heterozygote such as polybenzothiazoles, polybenzoxazoles, and polybenzimidazoles is added to the above polyphosphoric acid, methanesulfonic acid, sulfuric acid, or a mixture thereof. A solution in which a cyclic polymer compound is dissolved in such a manner that no liquid crystal phase is observed is used for spinning.

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
For 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 0.1 to 3 parts by weight.

The diluting solvent used to bring the solution to the concentration mentioned above may be the same as or different from the reaction solvent, and therefore in the present invention dilution using polyphosphoric acid, methanesulfonic acid and/or sulfuric acid is used. can do.

In addition to the above-mentioned polyphosphoric acid, methanesulfonic acid, and sulfuric acid, the solution can be diluted with chlorosulfuric acid, trifluorosulfuric acid, etc. within a range that does not impair the properties of the solution used in the present invention.

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 for coagulating the discharged material discharged from the discharge spout mold 3, and a winding device 5. 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, the dry jet 1-/
When employing the wet spinning method, spinning is carried out at a spinning temperature of usually 20 to 160°C, using a normal spinning nozzle of about 50 to 500 μm, and setting a draft ratio of usually 1.0 or more. Note that in order to perform spinning with the draft ratio as described above, it is possible to mechanically apply tension to the discharged yarn so that the draft ratio as described above is achieved, but it is also possible to spin the discharged yarn in an air bath as described above. By inserting the thread into the coagulation bath through the thread, a draft is generated due to the weight of the thread
In particular, by adjusting the discharge rate to one level without applying mechanical tension, spinning can be carried out at the draft ratio as described above.

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

By discharging the discharged yarn as described above into water and leaving it, the residual rate of phosphoric acid, methanesulfonic acid, or sulfuric acid in the fiber (coagulated yarn) is 0.1% by weight or less, preferably 0.0%.
By controlling the content to 1% by weight or less, fibers with excellent stretchability and strength can be obtained.

For example, FIG. 2 shows the relationship between the time the fibers obtained as described above are allowed to stand in water and the elongation at break of the fibers obtained by drying the coagulated threads thus obtained.

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. In other words, compared to a drawn fiber obtained by using a coagulated yarn that is placed in a coagulation bath and allowed to stand in the coagulation bath for less than one hour, the elongation at break of the drawn fiber increases as the standing time increases. The strength of the drawn fiber produced using the coagulated yarn left in the coagulation bath for 1 day (24 hours) is the highest. 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 P205 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 amount of polyphosphoric acid remaining in the PBO coagulated thread is 11% by weight or less, preferably 0. 01 weight is less than 1%.

The coagulated thread, which is left in water in this way and has a residual rate of polyphosphoric acid, methanesulfonic acid, or sulfuric acid as described above, has a low residual rate of polyphosphoric acid, methanesulfonic acid, or sulfuric acid, and is mainly made of mesh. The structure develops and becomes highly extensible.

The drawn fibers produced by the method of the present invention do not exhibit liquid crystallinity.

The fibers obtained in this way usually have a thickness of 10 to 50
0 pm, and the strength 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 do not undergo hydrolysis.

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 20°C.
The temperature is 0°C and the drying time is usually set to 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 in the range of 0.01% by weight.

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 may 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 such a low concentration that no liquid crystal phase is observed, and this solvent is used. Since the fibers are spun and left in water and the concentration of a specific solvent contained in the fibers is kept below a certain level, fibers with excellent spinnability and drawability can be 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 polymer compound that is particularly excellent in 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.

88.1 g of PPA solution) and 22.82 s of 4,6-diami2-1,3-benzenediol dino-hydrochloride (DAR) dissolved in 200 ml of resin ketone were mixed. After stirring this mixture,
Hydrogen chloride was removed from the DAR by heating to a temperature of 50-80° C. for about 20 hours under reduced pressure.

Then, 17.96 g of terephthalic acid (
TA) and further added 61.2 g of P2O5 to bring the content of P2O5 in this mixture to 87.2% by weight.
I made it.

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-phenylenebenzoxacyl) (P
Since this reaction solution contained 13.6% by weight of BO), it exhibited polarizing properties.

This reaction solution 1.45. PP prepared during the reaction to Og
By adding 794.0 g of solution A and stirring sufficiently, polarized light was no longer observed.

The PBO concentration in this solution was 2.1% by weight. Intrinsic viscosity -1,1,], dN/g (30℃,
Methanesulfonic acid) The solution obtained as 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, a discharge rate of 9.6 g/min, and a draft ratio of 1.
After being discharged into the air with an air gap of 3.5 cm under the following conditions, the yarn 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 was reduced to 0.0074% by weight.

After reducing the concentration of P2O 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 dried yarn was 0.01% by weight or less.

Further, the diameter of the obtained fiber was 120 μm, and it was found that the inside of this fiber had a network structure consisting of a portion where many precipitated particles aggregated and many void portions.

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 strength, and it was possible to obtain drawn fibers by drawing such fibers.

Examples 2 to 16 In Example 1, P in the PPA solution of PBO
Fibers were obtained in the same manner except that the B 2 O concentration, the draft ratio, and the time during which the discharged yarn was left 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, except that the reaction solution used to synthesize PBO was used as it was for spinning. The concentration of this solution was 13.6% by weight, and it exhibited polarizing properties.

The obtained fibers are liquid crystalline fibers, which are very 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. Furthermore, the elongation at break of the fiber evaluated in wet and dry conditions was 60%.

[Brief explanation of the drawing]

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. 2 is a strain rate-stress curve showing the relationship between the elongation at break and the dry fiber produced from the coagulated yarn obtained in the above. FIG. 3 is a graph showing the relationship between the time the discharged thread is left in water and the amount of polyphosphoric acid remaining in the coagulated thread. Attorney Shun Suzuki 1st Stretching rate (2g)

Claims (1)

[Claims] (1) Polybenzothiazoles, polybenzoxazoles, or polybenzimidazoles are dissolved in polyphosphoric acid, methanesulfonic acid, sulfuric acid, or a mixture thereof in a state in which no liquid crystal phase is observed, and the solution is obtained by spinning. The resulting polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers are left in water to reduce the residual rate of phosphoric acid, methanesulfonic acid, or sulfuric acid in the fibers to 0.1% by weight or less. A method for producing polybenzothiazole fibers, polybenzoxazole fibers, or polybenzimidazole fibers, characterized in that: