METHOD FOR PRODUCING FIBERS, FILMS AND MOLDINGS OF A POLYBENZAZOLE POLYMER (P)

Abstract

A method for producing films, fibers, and moldings of a polybenzazole polymer (P) by reacting at temperatures of 0 to 120 C. a mixture including (a) aromatic dicarboxylic compound(s) (I):

##STR00001##

wherein Ar.sup.1 is optionally substituted phenylene, naphthalenediyl, anthracenediyl, biphenyldiyl, diphenylmethanediyl, diphenyl ether diyl, diphenyl thio ether diyl, diphenyl sulfone diyl, benzophenonediyl, pyridinediyl, pyrimidinediyl, furandiyl, or thiophenediyl, substituents being F, Cl, Br, OR.sup.1, and C.sub.1-C.sub.10-alkyl, R.sup.1 being H or C.sub.1-C.sub.10-alkyl; X.sup.1 and X.sup.2 are independently-OR.sup.2, F, Cl, or Br, R.sup.2 being H, C.sub.1-C.sub.10-alkyl, C.sub.1-C.sub.10-alkenyl or a repeating unit (a):

##STR00002##

wherein m is a natural number from 1 to 50, and R.sup.3 is H, C.sub.1-C.sub.10-alkyl, or C.sub.1-C.sub.10-alkenyl; (b) aromatic diamino compound(s) of formula (IIa), (IIb), (IIc) and/or (IId); (c) at least one ionic liquid (IL), to obtain a product, processing the product at temperatures 0 to 100 C. and heating of the articles obtained at temperatures of 250 to 500 C.

Claims

1. A method for producing a film, fiber, or molding including a polybenzazole polymer, the method comprising reacting a reaction mixture at a first temperature in a range of from 0 to 120 C. to obtain a product mixture; processing the product mixture to give a film, fiber, or molding at a second temperature in a range of from 0 to 100 C., to obtain a processed film, fiber, or molding; and heating of the processed film, fiber, or molding at a third temperature in a range of from 250 to 500 C., wherein the reaction mixture comprises: (a) an aromatic dicarboxylic compound of formula (I): ##STR00018## wherein Ar.sup.1 is an optionally substituted phenylene, naphthalenediyl, anthracenediyl, biphenyldiyl, diphenylmethanediyl, diphenyl ether diyl, diphenyl thio ether diyl, diphenyl sulfone diyl, benzophenonediyl, pyridinediyl, pyrimidinediyl, furandiyl, or thiophenediyl, substituents being F, Cl, Br, OR.sup.1, or C.sub.1-C.sub.10-alkyl, and R.sup.1 being H or C.sub.1-C.sub.10-alkyl, X.sup.1 and X.sup.2 are independently OR.sup.2, F, Cl, or Br, R.sup.2 being H, C.sub.1-C.sub.10-alkyl, C.sub.1-C.sub.10-alkenyl, or a repeating unit of formula (Ia): ##STR00019## wherein m is a natural number from 1 to 50, and R.sup.3 is H, C.sub.1-C.sub.10-alkyl, or C.sub.1-C.sub.10-alkenyl; (b) an aromatic diamino compound of formula (IIa), (IIb), (IIc), and/or (IId): ##STR00020## wherein n is 0 or 1 Y.sup.1, Y.sup.2, Y.sup.3, and Y.sup.4 are independently H, OR.sup.4, or SR.sup.4, R.sup.4 being H, C.sub.1-C.sub.10-alkyl, trimethylsilyl, tert-butyldimethylsilyl, acetyl, or tert-butyloxycarbonyl, wherein at most one of Y.sup.1 and Y.sup.2 is H, and wherein at most one of Y.sup.3 and Y.sup.4 is H; Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4, Z.sup.5, Z.sup.6, Z.sup.7, and Z.sup.8 are independently NH.sub.2 or NH.sub.3.sup.+Q.sup., Q.sup. is F.sup., Cl.sup., Br.sup., I.sup., HSO.sub.4.sup., SO.sub.4.sup.2, H.sub.3CSO.sub.3.sup., p-H.sub.3CC.sub.6H.sub.4SO.sub.3.sup., or NO.sub.3.sup.; and (c) an ionic liquid.

2. The method of claim 1, wherein Ar.sup.1 is 1,3-phenylene, 1,4-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, anthracene-2,6-diyl, anthracene-9,10-diyl, biphenyl-4,4-diyl, diphenylmethane-4,4-diyl, diphenyl ether 4,4-diyl, diphenyl thioether 4,4-diyl, diphenyl sulfone 4,4-diyl, benzophenone-4,4-diyl, pyridine-2,5-diyl, pyrimidine-4,6-diyl, or furan-2,5-diyl and thiophene-2,5-diyl.

3. The method of claim 1, wherein the aromatic dicarboxylic compound (a) is terephthalic acid, terephthalic anhydride, terephthaloyl difluoride, terephthaloyl dichloride, terephthaloyl dibromide, C.sub.1-C.sub.10-alkyl esters of terephthalic acid, C.sub.1-C.sub.10-alkenyl esters of terephthalic acid, isophthalic acid, isophthalic anhydride, isophthaloyl difluoride, isophthaloyl dichloride, isophthaloyl dibromide, polyanhydrides of isophthalic acid, C.sub.1-C.sub.10-alkyl esters of isophthalic acid, and/or C.sub.1-C.sub.10-alkenyl esters of isophthalic acid.

4. The method of claim 1, wherein the aromatic diamino compound (b) is 4,6-diamino-1,3-dihydroxybenzene, 4,6-diamino-1,3-dihydroxybenzene dihydrochloride, 2,5-diamino-1,4-dihydroxybenzene, and/or 2,5-diamino-1,4-dihydroxybenzene dihydrochloride.

5. The method of claim 1, wherein the reaction mixture comprises, based on total reaction mixture weight, 5 to 25 wt. % of the aromatic dicarboxylic compound (a), 5 to 25 wt. % of the aromatic diamino compound (b), and 50 to 90 wt. % of the ionic liquid (c).

6. The method of claim 1, wherein the ionic liquid is of formula (III):
[C].sub.n.sup.+[A].sup.n(III), wherein n is 1, 2, 3, or 4, [C].sub.n.sup.+ is a cation including optionally substituted imidazolium, imidazolinium, imidazolidinium, quaternary ammonium, quaternary phosphonium, pyrazolium, pyrazolinium, pyridinium, pyridazinium, pyrimidinium, pyrazinium, pyrrolidinium, guanidinium, thiazolium, oxazolium, triazolium, 1,8-diazabicyclo[5.4.0]undec-7-enium, and/or 1,8-diazabicyclo[4.3.0]non-5-enium, enium, and/or an oligomer and/or polymer comprising any of these cations, substituents being C.sub.1-C.sub.18-alkyl, C.sub.5-C.sub.12-cycloalkyl, and/or C.sub.6-C.sub.14-aryl, [A].sup.n is a halide comprising anion, cyanide, thiocyanate, cyanate, isocyanate, nitrite, nitrate, sulfate, sulfite, sulfonate, carboxylate, borate, boronate, carbonate, carbonate ester, amide, carboximidate, sulfonyl imidate, bis(sulfonyl) imidate, alkoxide, or aryl oxide, optionally comprising a substituent, the substituent being C.sub.1-C.sub.18-alkyl, C.sub.5-C.sub.12-cycloalkyl and/or C.sub.6-C.sub.4-aryl.

7. The method of claim 6, wherein the ionic liquid comprises an imidazolium cation of formula (IV) as [C].sub.n.sup.+: ##STR00021## wherein R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are independently H, C.sub.1-C.sub.18-alkyl, C.sub.5-C.sub.12-cycloalkyl, or C.sub.6-C.sub.14-aryl.

8. The method of claim 6, wherein [C].sub.n.sup.+ is 1-methylimidazolium, 1-methyl-2-ethylimidazolium, 1-methyl-3-octylimidazolium, 1,2-dimethylimidazolium, 1,3-dimethylimidazolium, 2,3-dimethylimidazolium, 3,4-dimethylimidazolium, 1,2,3-trimethylimidazolium, 1,3,4-trimethylimidazolium, 1,3,4,5-tetramethylimidazolium, 1-ethylimidazolium, 1-ethyl-2-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 2-ethyl-3,4-dimethylimidazolium, 1-propylimidazolium, 1-propyl-2-methylimidazolium, 1-propyl-3-methylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1,3-dipropylimidazolium, 1-butylimidazolium, 1-butyl-2-methylimidazolium, 1-butyl-3-methylimidazolium, 1-butyl-4-methylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-butyl-3,4-dimethylimidazolium, 1-butyl-3,4,5-trimethylimidazolium, 1-butyl-2-ethylimidazolium, 1-butyl-3-ethyl-imidazolium, 1-butyl-2-ethyl-5-methylimidazolium, 1,3-dibutylimidazolium, 1,3-dibutyl-2-methylimidazolium, 1-pentylimidazolium, 1-pentyl-2-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-pentyl-2,3-dimethylimidazolium, 1-hexylimidazolium, 1-hexyl-2-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl-2-methylimidazolium, 1-octyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, 1-dodecyl-3-methylimidazolium, 1-tetradecyl-3-methylimidazolium, 1-hexadecyl-3-methylimidazolium, and/or 1-benzyl-3-methylimidazolium.

9. The method of claim 1, wherein the ionic liquid is 1-methylimidazolium chloride, 1-ethylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-butylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1,3-diethylimidazolium chloride, 1,3-dibutylimidazolium chloride, 1-methylimidazolium tetrachloroaluminate, 1-ethylimidazolium tetrachloroaluminate, 1-ethyl-3-methylimidazolium tetrachloroaluminate, 1,3-diethylimidazolium tetrachloroaluminate, 1-butylimidazolium tetrachloroaluminate, 1-butyl-3-methylimidazolium tetrachloroaluminate, and/or 1,3-dibutylimidazolium tetrachloroaluminate.

10. The method of claim 1, wherein the reacting of the reaction mixture is conducted in the presence of a basic compound comprising trialkylamine, imidazole, pyridine, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, lithium hydride, sodium hydride, potassium hydride, magnesium hydride, and/or calcium hydride.

11. The method of claim 1, wherein the reaction mixture comprises the aromatic dicarboxylic compound (a), the aromatic diamino compound (b), and the ionic liquid (c) in a combination of terephthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, terephthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, terephthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1,3-diethylimidazolium chloride, terephthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-methylimidazolium chloride, terephthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, terephthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, terephthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1,3-diethylimidazolium chloride, terephthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-methylimidazolium chloride, wherein the aromatic diamino compound (b) is optionally a corresponding dihydrochloride.

12. A fiber, film, or molding obtained by the method of claim 1.

13. A method of producing an article including a cable, rope, cord, glass fiber sheathing, fiber-reinforced rubber material, fiber-reinforced building material, brake lining suitable for disk brake, non-woven material, or textile optionally for a bullet-proof vest, temperature-resistant protective clothing, helmet layer, supply cable sheath, textile-reinforced building material, and/or textile concrete suitable for restoration or repair of building, the method comprising carrying out the method of claim 1; and processing the fiber, film, or molding into the article.

14. A thermally stable membrane configured for gas separation, proton-conducting membrane, electrooptic device, or light emitting diode made by a method comprising the method of claim 1.

15. A high temperature-resistant polymeric material, made by a method comprising the method of claim 1.

16. The method of claim 1, wherein the reaction mixture comprises the aromatic dicarboxylic compound (a), the aromatic diamino compound (b), and the ionic liquid (c) in a combination of terephthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, terephthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, terephthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1,3-diethylimidazolium chloride, terephthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-methylimidazolium chloride, terephthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, terephthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, terephthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1,3-diethylimidazolium chloride, terephthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-methylimidazolium chloride, wherein the aromatic diamino compound (b) is optionally a corresponding dihydrochloride.

17. The method of claim 1, wherein the reaction mixture comprises the aromatic dicarboxylic compound (a), the aromatic diamino compound (b), and the ionic liquid (c) in a combination of isophthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, isophthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, isophthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1,3-diethylimidazolium chloride, isophthaloyl dichloride, 4,6-diamino-1,3-dihydroxybenzene, and 1-methylimidazolium chloride, isophthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, isophthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, isophthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1,3-diethylimidazolium chloride, isophthaloyl dichloride, 2,5-diamino-1,4-dihydroxybenzene, and 1-methylimidazolium chloride, wherein the aromatic diamino compound (b) is optionally a corresponding dihydrochloride.

18. The method of claim 1, wherein the reaction mixture comprises the aromatic dicarboxylic compound (a), the aromatic diamino compound (b), and the ionic liquid (c) in a combination of isophthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, isophthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, isophthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1,3-diethylimidazolium chloride, isophthalic anhydride, 4,6-diamino-1,3-dihydroxybenzene, and 1-methylimidazolium chloride, isophthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-butyl-3-methylimidazolium chloride, isophthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-ethyl-3-methylimidazolium chloride, isophthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1,3-diethylimidazolium chloride, isophthalic anhydride, 2,5-diamino-1,4-dihydroxybenzene, and 1-methylimidazolium chloride, wherein the aromatic diamino compound (b) is optionally a corresponding dihydrochloride.

Description

EXAMPLES

[0199] The following methods were used to determine the following parameters:

[0200] Tensile strength and elastic modulus of fibers in accordance with DIN EN ISO 5079. Viscosity number in accordance with DIN EN ISO 1628-1 at 25 C. in methanesulfonic acid.

[0201] Phosphorus determination (method MB 2018/05, BASF SE, Kompetenzzentrum Analytik) as described in the following:

[0202] Portions of the phosphorus-containing sample of 0.2 to 0.3 g are solubilized at 320 C. with conc. sulfuric acid (ca. 96% by weight H.sub.2SO.sub.4), concentrated nitric acid (ca. 65% by weight HNO.sub.3) and cesium sulfate solution (50 g of cesium sulfate Cs.sub.2SO.sub.4 (purity 99.9) are dissolved with water to a volume of 1000 ml). The residue obtained is treated with mixed acid (conc. nitric acid+conc. perchloric acid (ca. 70% by weight HClO.sub.4)+conc. sulfuric acid in a ratio by volume of 2:1:1) at ca. 160 C. The excess acids are evaporated and the residue is boiled and dissolved with 25% by volume hydrochloric acid (mixture of conc. hydrochloric acid (ca. 36% by weight HCl)+water in a ratio by volume of 3:1) and deionized water. The precise volume is determined via back weighing and calculation of the density.

[0203] In the resulting digested solution, phosphorus is measured by atomic emission spectrometry (ICP-OES).

[0204] Matrix digestion solution and standards: c(HCl) ca. 0.6 mol/L, ca. 0.2% (m/v) Cs.sub.2SO.sub.4.

[0205] Instrument: ICP-OES Agilent 5100 spectrometer.

[0206] Measurement conditions: integration time 10 sec, generator 1200 W, conical nebulizer 1 ml, spectral line (nm): P 213.618; corrections: Sc 361.383 nm (internal standard), calibration: external.

1. General Experimental Method for Producing the Product Mixture (P.SUB.VG.)

[0207] A 750 ml double-jacketed glass reactor equipped with an anchor stirrer and distillation head was filled with 1-butyl-3-methylimidazolium chloride (BMIM-Cl). The ionic liquid (IL) was dried at 130 C. while stirring (100 rpm) under nitrogen feed (60 L/h) and reduced pressure (50 mbar absolute pressure) until a water content of <0.03% was achieved (measurement by Karl-Fischer titration of an aliquot withdrawn). After temperature-conditioning of the IL at 75 C., 4,6-diaminoresorcinol dihydrochloride (IUPAC name 4,6-diamino-1,3-dihydroxybenzene dihydrochloride) (DAR) was added and stirred overnight until a homogeneous solution was obtained (ca. 16 h). Subsequently, terephthaloyl dichloride (TC) was added in five portions as a solid while stirring (100 rpm), wherein there were ca. 15 min between successive metered additions. The total metered addition amount of these five metered additions were 50, 75, 88, 95, 98 mol % TC based on the amount of DAR used. Reaction gases were discharged by means of a nitrogen stream (ca. 90 L/h) at negative pressure (ca. 50 mbar absolute pressure). After the fifth metered addition of the appropriate TC amount (see above), the torque of the stirrer increased slowly until a torque of ca. 80 Ncm was reached, whereupon the stirring speed was then reduced (to ca. 20 rpm). If the torque did not further increase, further TC was added (total amount of the six metered additions therefore corresponded to 100.1 to 100.6 mol % with respect to the amount of DAR), as a result of which the torque rapidly increased. The stirring speed was further reduced (ca. 10 rpm) and the mixture was stirred further until there was no further torque increase. Finally, the mixture was kept at reduced pressure (ca. 50 mbar) without further stirring in order to reduce the amount of gas inclusions in the solution, whereby further processing (for example spinning) is generally facilitated. After releasing the reaction vessel to standard pressure (ca. 1013 mbar), an aliquot of the solution was withdrawn for rheological characterization (see characterization).

Examples V1 to V3

[0208]

TABLE-US-00002 TABLE 1.1 Amount of BMIM-Cl Excess H.sub.2O Amount of Amount of TC to T in IL DAR TSC DAR V No. [ C.] [g] [mmol] [%] [g] [mmol] [g] [mmol] (mol %) Additive 1 75 351.09 2010 0.024 45.970 215.76 44.023 216.84 0.581 2 75 204.85 1173 0.026 26.822 125.89 25.558 125.89 0.090 3 mol % LiCl/DAR 3 75 309.08 1770 0.026 40.469 189.94 38.755 190.89 0.585

Characterization

[0209] The polymer solutions were characterized rheologically on a DHR type rheometer from TA Instruments, Newcastle (USA) by frequency sweeps at constant temperature in each case. The frequencies were spaced logarithmically equidistant between 250 and 1 rad/s recording 10 points per decade. The temperature was varied stepwise between 10 C. and 60 C. in steps of 10K. A lower Peltier plate with nitrogen-flushed covering composed of acrylic glass served as temperature-control system to avoid condensation (necessarily required in view of the hygroscopic properties of the IL used). The upper plate had a diameter of 25 mm at a slit width of 1 mm. The deformation imposed was consistently 10%.

[0210] From the results of the 6 isothermal frequency experiments for each solution, a master curve was generated at a reference temperature of 20 C. The horizontal shift factors a.sub.T were fitted to the WLF equation according to Malcolm L. Williams, Robert F. Landel and John D. Ferry The Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-forming Liquids, Journal of the American Chemical Society, 1955.

[00001]${\log }_{10}.Math..Math.a_T=\frac{-c_1\left(T-T_{\mathrm{ref}}\right)}{c_2+T-T_{\mathrm{ref}}}.$

[0211] For the vertical shift factors b.sub.T only the temperature was taken into consideration

[00002]$b_T=\frac{T_{\mathrm{ref}}}{T},$

where all temperatures here are to be specified in Kelvin.

[0212] The following solutions were evaluated as suitable for spinning in which the correlation between the loss factor tan(b) and the value of the complex viscosity |*| at any desired but fixed frequency in a certain process window was (tan()/|*|1, at 0.1 rad/s, where |*|=45 000-90 000 Pa*s). This process window was determined empirically.

2. Spin Tests with PVG:

[0213] A piston spinning system from Fourn served as spinning apparatus. Prior to the actual spinning test, the spinning solution in the spinning piston was made as gas bubble-free as possible.

[0214] The filled piston was installed in the piston spinning system and heated to the spinning temperature, see Table 2.1. As nozzles, either a 144 hole 100 m nozzle or a 64 hole 150 m nozzle with an L/D ratio of 3/1 was used. It was spun vertically downwards. The pressures formed here were highly dependent on the temperature, the solution concentration, the piston feed rate and the nozzle to be used. Generally, they were 60 to 100 bar. The discharge rate of the spinning composition was 1 to 2 m/min. The filament bundle thus formed was passed to a coagulation bath of demineralized water at a temperature of ca. 25 C. across an air gap (distance of nozzle to edge of coagulation bath) of 10 to 100 mm. The filament bundle was passed from the bath to a godet by means of a deflecting roller. The rate of which determines the draw ratio. Stable spinning tests could be achieved at a stretching of 20% and 30%. Spinning tests with 50% stretching and more resulted in relatively frequent torn filaments in the fiber bundle. The residence time in the coagulation bath was ca. 40 s.

[0215] For washing, the fiber bundle was fed through a demineralized water bath heated to 88 to 90 C. The residence time here was ca. 32 s. In this case the fiber was stretched by 20% via a godet. The fiber was then fed by means of a godet through hot air channel at 120 for drying. The residence time in the drying process was ca. 34 s. From the latter godet, the fiber thus formed was spooled with a tension-controlled winder from Qeriklon-Barmag (Wuff 6e) with a pre-tension force of 100 cN. The results are listed in Table 2.1 below. The V No. 1, 2 3 herein signifies the batches stated in Table 1.1, and the corresponding spinning tests A, B, C result in samples 1A, 1B, 1C, 2A and 3A, which were used in the condensations as presented in 3.1 and 3.2.

TABLE-US-00003 TABLE 2.1 Spinning solution Unit V No. 1 V No. 2 V No. 3 Additive [mol %] 14.3 15 mol % 14.3 LiCl Viscosity at 0.1 rad/s [(Pa .Math. s)] 49556 86867 70960 tan delta at 0.1 rad/s 1.109 0.989 0.982 Spinning tests A B C A A Nozzle diameter [m] 150 150 150 150 150 Temperature [ C.] 50 52 53 25 66 Length of air gap [mm] 100 100 100 100 100 Stretching nozzle [%] 80 30 40 30 23 Stretching bath [%] 15 17 Total stretching [%] 80 30 40 50 44 Filament tearing yes no no no no Fiber properties Elongation at break [%] 47 53 50 32 56 Tensile strength [cN/tex] 16.4 14.5 14.8 13.6 13.2 Tensile strength [GPa] 0.16 0.15 0.15 0.14 0.13 Fineness [dtex] 15.0 19.6 18.1 20.0 11.0 Elastic modulus [cN/tex] 492 456 465 426 475 Elastic modulus [GPa] 4.9 4.6 4.7 4.3 4.8

3.1 PBO Condensation No. 1:

[0216] The fibers obtained from the spinning tests were fed through an oven purged with nitrogen at 42000 (oven length 3 m, 8 heating zones). The stretching of the material was achieved by a thread tensioner in the unwinding unit. Here, a defined rolling resistance was predetermined.

[0217] At the oven outlet, the thread was guided via a godet to a tension-controlled winder. Stable stretchings were 20 to 30%; at higher stretchings there was partial filament tearing. The residence times in this process were ca. 60 min. The tests and results are summarized in Table 3.1.1.

TABLE-US-00004 TABLE 3.1.1 1B- 1B- 1C- 2A- 2A- 2A- 2A- T K1 K2 K1 K1 K2 K3 K4 Residence time at [min] ~60 ~60 ~60 53 56 58 59 T = 420 C. Stretching [%] 15 30 32 14 28 38 46 Filament tearing no no no no no yes yes Elongation at [%] 1.8 1.3 1.1 1.6 1 0.8 0.8 break Tensile strength [cN/tex] 33.2 35.3 37.3 31.2 34.3 40.9 42.3 Tensile strength [GPa] 0.50 0.53 0.56 0.47 0.51 0.61 0.63 Fineness [dtex] 11.36 11.35 9.54 11.57 10.43 9.88 9.95 Elastic modulus [cN/tex] 2754 3515 4181 2691 4006 5568 5716 Elastic modulus [GPa] 41 53 63 40 60 84 86

[0218] Herein, tests with the different aramid fibers 1B, 1C and 2A according to the invention are presented in which in each case the stretching was varied, except 1C-K1. It can be seen from Table 3.1.1 that the elastic modulus and tensile strength of the aramid fiber according to the invention increase markedly after condensation, columns with the headings 1B-K1, 1B-K2 and columns 2A-K1 to 2A-K4.

[0219] Moreover, it can be seen that when a higher stretching was applied already during the production of the aramid fiber according to the invention (compare column 1B and 1C in Table 2.1, line Total stretching), this has an advantageous effect on the properties (for example elastic modulus, tensile strength) of the fibers of PBO which were obtained at comparable stretchings during conversion of aramid fiber to fiber of PBO, compare Table 3.1.1 1B-K2 with 1C-K1.

3.2 PBO Condensation No. 2:

[0220] In these tests, the residence time was shortened from ca. 60 min to ca. 10 min. The fibers were fed through an oven (oven length 3 m, 6 heating zones) purged with inert gas (N.sub.2), in which the following heating program (HP) was used:

TABLE-US-00005 HP1 HP2 HP3 T ( C.) Zone 1 420 280 320 T ( C.) Zone 2 420 320 360 T ( C.) Zone 3 420 360 420 T ( C.) Zone 4 420 400 420 T ( C.) Zone 5 420 420 420 T ( C.) Zone 6 420 420 420

[0221] The residence time per heating zone was of the total residence time which can be seen from the following table. Stretching of the material was accomplished by the speed difference of two godets (1 oven inlet, 1 oven outlet). The PBO fiber obtained was spooled with a tension-controlled winder. Stable stretchings were 20 to 30%; at higher stretchings there was partial filament tearing. The tests and results are summarized in Table 3.2.1 and 3.2.2.

TABLE-US-00006 TABLE 3.2.1 3A- 3A- 3A- 3A- 3A- 3A- 3A K1 K2 K3 K4 K5 K6 Heating program HP1 HP1 HP1 HP1 HP2 HP2 Total residence time [min] 54.2 36.8 27.3 13.6 54.6 27.3 Stretching [%] 44 20 20 20 20 20 20 Elongation at break [%] 56 2.6 2.4 2 2.1 3.3 2.6 Tensile strength [cN/tex] 12.3 36.2 34.7 34.5 33.3 34.1 31.6 Tensile strength [GPa] 0.18 0.54 0.52 0.52 0.50 0.51 0.47 Fineness [dtex] 11.01 6.34 6.67 6.1 6.43 6.96 6.73 Elastic modulus [cN/tex] 475 2626 2594 2774 2703 2237 2270 Elastic modulus [GPa] 7 39 39 42 41 34 34

[0222] Presented herein are tests 3A-K1 to 3A-K6 in which, for example, the heating program (HP1, HP2) and/or the total residence time were varied and the stretching was not varied. It can be seen from Table 3.2.1 that, for example, the elastic modulus and tensile strength of the aramid fiber according to the invention (column with heading 3A) increase markedly after condensation, columns with the headings 3A-K1 to 3A-K6.

TABLE-US-00007 TABLE 3.2.2 3A- 3A- 3A- 3A- 3A- 3A- 3A- K7 K8 K9 K10 K11 K12 K13 Heating program HP2 HP2 HP2 HP2 HP3 HP3 HP3 Total residence time [min] 28.1 28.7 14.3 14.6 10.9 8.2 8.7 Stretching [%] 28 35 35 40 20 20 38 Elongation at break [%] 2.4 1.4 1.3 1.3 1.7 1.7 1.1 Tensile strength [cN/tex] 34.4 38 41.9 42.5 33.7 32.4 42.7 Tensile strength [GPa] 0.52 0.57 0.63 0.64 0.51 0.49 0.64 Fineness [dtex] 6.66 5.92 5.34 5.19 6.35 6.24 5.26 Elastic modulus [cN/tex] 2686 3767 4285 4491 2909 2855 4777 Elastic modulus [GPa] 40 57 64 67 44 43 72

[0223] Presented herein are tests 3A-K7 to 3A-K13 in which, for example, the heating program (HP1, HP2) and/or the total residence time were varied and the stretching was additionally varied. It can be seen from Table 3.2.2 that, by higher stretching, for example the elastic modulus and tensile strength of the aramid fiber according to the invention (column with heading 3A) increase further after condensation, columns with the headings 3A-K7 to 3A-K13.

4. Investigations on the Stability of the PBO Fiber to Hydrolysis and Aqueous Alkali.

4.1 Hydrolysis

[0224] The hydrolysis of a fiber of PBO according to the invention, namely 1B-K2 of Table 3.1.1, was carried out according to the conditions described in the following, as listed in the technical data sheet of the commercial PBO fiber Zylon (PBO Fiber Zylon Technical Information, 2005, 1-18.). The fibers of PBO according to the invention were stored at 80 C. and 80% relative air humidity and the tensile strength determined after various time intervals in accordance with DIN EN ISO 5079. No significant deterioration in tensile strength could be detected after 50 days treatment; compare Table 4.1.1. In comparison thereto, the PBO fiber Zylon AS loses ca. 30% tensile strength after 50 days according to the information in the previously mentioned technical data sheet of Toyobo.

TABLE-US-00008 TABLE 4.1.1 Tensile strength [cN/tex] After x days 35.3 0 (initial value) 34.3 10 34 23 34 50

4.2 Stability to Alkali

[0225] The stability to alkali of a PBO fiber according to the invention, namely 1B-K2 of Table 3.1.1, was carried out according to the conditions described in the following, as listed in the technical data sheet of the commercial PBO fiber Zylon (PBO Fiber Zylon Technical Information, 2005, 1-18.). The fibers of PBO according to the invention were stored at 80 C. in aqueous alkali (10% by weight NaOH) and the tensile strength was determined after 100 h. Whereas the loss of tensile strength of the fibers of PBO according to the invention was only ca. 8% of the initial strength, the PBO fiber Zylon AS loses ca. 70% of the original tensile strength according to the information in the previously mentioned technical data sheet of Toyobo.

4.3 Stability to UV

[0226] The stability to UV of a PBO fiber according to the invention, namely 1B-K2 of Table 3.1.1, was carried out according to the conditions described in the following, as listed in a similar design also in the technical data sheet of the commercial PBO fiber Zylon (PBO Fiber Zylon Technical Information, 2005, 1-18.). The fibers of PBO according to the invention were exposed in a xenon laboratory weathering device to the conditions below and the tensile strength was determined after 168 h. Lamp type: Xenon 320, dose rate 42 W/m.sup.2, temperature: 30 C., relative air humidity: 60%. Whereas the loss of tensile strength of the fibers of PBO according to the invention was only ca. 9% of the initial strength, the PBO fiber Zylon AS loses ca. 75% of the original tensile strength.