BE826311A - POLYARYLENE-OXADIAZOLES-1,3,4 MODIFICATIONS, THEIR PREPARATION PROCESS AND PROCESS FOR THE PREPARATION OF POLYOXADIAZOLE-DERIVED FIBERS - Google Patents

Description

       

  "Modified polyarylene-oxadiazoles-1,3,4, method of preparation thereof and method of preparation of derivatized polyoxadiazole fibers".

  
The present invention relates to polyaryleneoxadiazoles-1,3,4-, their preparation process as well as a process for the preparation of derived fibers.

  
 <EMI ID = 1.1>

  
special measures for the personnel of various industries as well as for the manufacture of standard flame-retardant clothing; they are also used for the manufacture of decorative fire-retardant fabrics or furnishing fabrics (curtains, rugs, tapestries, etc.) and for the manufacture of technical rubber articles used at high temperatures and subjected to alternating deformations, such as as automotive and aircraft tires, belts and conveyor belts.

  
Polyarylene oxadiazoles1,3,4 are already known, the nacromolecules of which consist of the following units:

  

 <EMI ID = 2.1>


  
 <EMI ID = 3.1>

  
monocyclic arylene radicals.

  
A process for the preparation of polyarylene-oxadiazoles-1,3,4 is already known which comprises the stages of polycondensation of dichlorides of arylenedicarboxylic acids on dihydrazides of arylene-dicarboxylic acids in sol-

  
 <EMI ID = 4.1>

  
obtained by heating, in the absence or in the presence of catalysts
(See Journal of Polymer Science, A2, N [deg.] 3, pp. 1147, 1157, 1171 (1964) and Polymer Preprints, 9, N [deg.] 2, 109.1 (1968)).

  
The main disadvantage of this process is that it comprises two stages which complicates the preparation of the polymers as well as of the derived fibers.

  
 <EMI ID = 5.1>

  
economy and simplicity of industrialization, consists in synthesizing in a single step of polyarylene-oxadiazoles1,3,4. This process consists of heating in an oleum, to 85-
1451, Ci hydrazine sulfate with arylenedicarboxylic acids (terephthalic acid, isophthalic acid, mixtures of terephthalic acid-isophthalic acid, polycyclic acids

  
 <EMI ID = 6.1>

  
(1970), 29959 (1968), 21903 (1971), 21901 (1971), 16904 (1971); Journal of Polymer Science, A3, 45, 1965 and Journal of Applied

  
 <EMI ID = 7.1>

  
obtained on the basis of terephthalic and isophthalic acids which are the most promising from the point of view of the preparation of fibers, given their relatively low price and the accessibility of derived polymers which are characterized by a sufficiently high molecular mass.

  
Another known pa &#65533; a process for preparing polyoxadiazole fibers from polyarylene-oxadiazoles-1,3,4 which is obtained by polycondensation of the monomers in an oleum. This process consists in diluting the reaction solutions which form after the completion of the polycondensation with concentrated sulfuric acid and in extruding the spinning solutions obtained in a bath of preconstituted.

  
 <EMI ID = 8.1>

  
sulfuric. The fiber thus obtained is subjected to a plasticizer drawing, it is released by washing with sulfuric acid and it is subjected to a heat treatment (cf. Journal of Applied Polymer

  
 <EMI ID = 9.1>

  
class C3R).

  
A serious drawback of polyoxadiazoles and derived fibers, obtained by known methods, is their combustibility. Ignited and then removed from the flame of a burner, polyoxadiazoles and derived fibers burn completely in the open. The combustibility of polyoxadiazole fibers restricts their field of use. In addition, the known polyoxadiazole fibers, based on terephthalic and isophthalic acids, exhibit insufficient resistance to fatigue under the effect of deformations.

  
The number of double bends of the fiber until breaking, determined on a device of the type DP-15 from the Shopper Company under a load of 5 kgf / cm <2>, does not exceed
4000 or 5000 whereas for a capron fiber the number of double bends determined for the same load on this same device is 25000 to 30,000. This insufficient fatigue resistance limits the applications of known polyoxadiazole fibers for the purpose of manufacture technical rubber works which are explained under alternating deformations.

  
An aim of the present invention consists in eliminating the aforementioned drawbacks.

  
It has therefore been proposed to create polyaryleneoxadiazoles-1,3,4, which are suitable for spinning fibers and which exhibit better flexural stability.

  
and lower combustibility, as well as to create a process

  
 <EMI ID = 10.1>

  
preparation of derivative fibers.

  
The solution consists in using new polyarylene-oxadiazoles-1,3,4, in applying their preparation process and in using a process for preparing fibers derived from these polymers.

  
The polyarylene-oxadiazoles-1,3,4 proposed according to the present invention are compounds whose macromolecules consist of the following units:

  

 <EMI ID = 11.1>


  
where R 'represents a phenylene or diphenylene radical, and R "represents a bromo-phenylene or bromodiphenylene radical, R (Br])

  
, a meta-aminophenylene radical

  

 <EMI ID = 12.1>


  
or a radical

  
4,4 'azodiphenylene

  

 <EMI ID = 13.1>


  
, the maximum molar content

  
mum in units containing a bromophenylene or bromodiphé radical

  
 <EMI ID = 14.1>

  
 <EMI ID = 15.1>

  
 <EMI ID = 16.1>

  
According to the invention, the process for preparing the aforementioned polyoxadiazoles consists in carrying out the polycondensation of hydrazone sulphate on isophthalic acid and / or terephthalic acid, at a temperature of 85 to 145 [deg.] C, in oleum, in the presence of an additive consisting of salts of hydrobromic acid, of 5-amino-isophthalic acid or

  
with azobenzene-dicarboxylic acid-4,4 '.

  
Thanks to the use of additives of this kind in the synthesis of polyoxadiazoles, modifying elements such as bromine atoms, azo-N = N- groups as well as amino-aromatic groups are introduced into the macromolecules of the polymers which are substituted for the hydrogen atoms of the benzene rings. The introduction of atoms of

  
bromine reduces the combustibility of polyoxadiazoles, and the introduction of azo groups and amino-aromatic groups raises the flexural stability of polyoxadiazole fibers, i.e.

  
 <EMI ID = 17.1>

  
Troduction of an additive confers on a polyary-lene-oxadiazole-1,3,4 macromolecule a chemical structure which improves all the properties of polyoxadiazole fibers by reducing their combustibility as well as their fatigue at alternating deformations.

  
As reagents introducing bromine into the macromolecules of the polyoxadiazoles, it is proposed to use bromides, such as KBr or NaBr. These salts in an oleum undergo oxidation, releasing elemental bromine following the reaction:

  

 <EMI ID = 18.1>


  
To obtain polyoxadiazoles brominated during their synthesis from monomers in oleum, it is also possible to use elemental bromine as an agent for brominating. However, its cost price is much higher

  
 <EMI ID = 19.1>

  
tions than bromides.

  
As modifying reagents introducing azo and amino groups into the polyarylene-oxadiazoles-1,3,4 macromolecules, it is proposed according to the present invention to use arylene-azodicarboxylic acids HOOCArN = N-Ar COOH, in particular azobenzene acid -dicarboxylic-

  
4.4 ',

  

 <EMI ID = 20.1>


  
as well as amino acids

  
arylenedicarboxylic HOOCAr (NH2) COOH., in particular the acid

  
amino-5-isophthalic

  

 <EMI ID = 21.1>


  
The polyarylene oxadiazoles .1,3,4 can be used as such as fibrogenic products. However, it is more advantageous to use them as additives to less expensive and more accessible arylene dicarboxylic acids, such as terephthalic acid and / or isophthalic acid. To obtain polyoxadiazoles based on terephthalic and / or isophthalic acid, it is advantageous to use 5-amino-isophthalic acid additives in a proportion not exceeding 30 mol%, in order to avoid a drop in the molecular mass of the products. polymers obtained as well as a rapid deterioration of the mechanical strength of the polyoxadiazole fibers derived therefrom.

   In the case where azobenzene-dicarboxylic-4,4 'acid is used, its amount added to tetephthalic acid and / or isophthalic acid is not limited, azobenzene-dicarboxylic acid-4, 4 ', in the absence of other dicarboxylic acids, lending itself to the preparation of macromolecular polyoxadiazoles as well as sufficiently strong derived fibers.

  
As arylene-dicarboxylic acids one can use any aromatic dicarboxylic acids which do not disintegrate under the action of hot oleum and which

  
do not undergo sulfonation by oleum. From the point of view of cost, the tendency for macromolecule formation, it is preferable to use terephthalic acid and / or isophthalic acid.

  
The arylene-dicarboxylic acid and the hydrazine sulfate are taken in practically equimolecular proportions. However, in cases where the heated reaction liquor does not thicken, it is recommended to take an excess of hydrazine sulphate of at most 20% of the stoichiometric proportion.

  
It is advisable to introduce into the mixture of monomers the same excess of hydrazine sulphate before the polycondensation in the case where it is desired to obtain a polymer of a sufficiently high molecular mass and a high degree of bromination.

  
 <EMI ID = 22.1>

  
ditions of iodine in proportions up to 10% of the mass of the bromide optionally used. In the presence of these additives, the rate and degree of halogenation of the polymer increases considerably.

  
The lower limit of the quantities of bromination agents used which make it possible to obtain polyoxadiazoles of reduced combustibility, in particular self-extinguishing polyoxadiazoles, depends on the chemical characteristics of the arylenedicarboxylic acids used. The upper limit depends on the use of the polymers, since the molecular weight of the polymers drops as the degree of bromination increases. To obtain self-extinguishable fibrogenic polyoxadiazoles based on aromatic dicarboxylic acids in the presence of iodine additives, the bromide / dicarboxylic acid molar ratio or mixture of aromatic dicarboxylic acids is taken in a range of 0.1 / 1 up to 1.5 / 1.

  
To obtain a polymer with maximum bromine content, giving fibers of increased mechanical resistance, it is recommended to introduce the bromide before polycondensation in a suspension of dicarboxylic acid or a mixture of dicarboxylic acids. in oleum, to bring the mixture obtained to a temperature of 50 [deg.] to 100 [deg.] C, then adding hydrazine sulfate and heating to a temperature of
100 [deg.] To 145 [deg.] C.

  
Following the inversion, the process for preparing the fiber consists of extruding it from solutions (liquors) of spinning in sulfuric acid which contain the

  
 <EMI ID = 23.1>

  
a 30-55% aqueous solution of sulfuric acid with a content of <EMI ID = 24.1>

  
tifying freshly spun fiber in a ratio of 1/2 to 1/6 and strengthening this fiber by stretching it at a temperature

  
 <EMI ID = 25.1>

  
The proposed process for the preparation of polyaryleneoxadiazoles-1,3,4.modified according to the invention is simple to industrialize because it simply consists in heating a mixture of raw materials with stirring. The reaction liquors obtained are directly used for the preparation of the spinning solutions. The polymers are obtained in practically quantitative yield. Arylene-dicarboxylic acids used as the most promising raw materials,

  
namely terephthalic acid and isophthalic acid, are relatively inexpensive products of great gold synthesis.

  
 <EMI ID = 26.1>

  
Isophthalic acid and 4,4 'azobenzenedicarboxylic acid are easily obtained starting from isophthalic acid and 4-nitro-benzoic acid, respectively. Oleum, NaBr, KBr and sulfuric acid are inexpensive products of inorganic chemistry.

  
It can therefore be seen that the method according to the invention is simple and economical.

  
The process according to the invention is applied as follows.

  
We can introduce bromides in three different ways:
a) they can be placed in a suspension with an <EMI ID = 27.1>

  
and / or isophthalic acid, in oleum. The mixture is then brought to a temperature of 50 to 100 [deg.] C for a period of time necessary to complete the bromination of the arylene dicarboxylic acid (2 to 5 hours), then adding the sulfate <EMI ID = 28.1 > <EMI ID = 29.1> c) they can be introduced, finally, into a reaction polymer solution, after completion of the polycondensation, bringing the mixture to a temperature of 50 to
100 [deg.] C for 2 to 5 hours. The first version is the best, because it leads to the formation of polymers characterized by a higher degree of bromination and which lend themselves to fiber extrusion of higher mechanical strength.

The proposed process for preparing brominated polyary-lene-oxadiazoles-1,3,4 in its optimal version (version

  
a) is carried out as follows. The oleum, arylene-dicarboxylic acid, a bromide and, optionally, an addition of crystallized iodine are placed in a reactor and the mixture is brought, with stirring, to a temperature of 50 [deg.] To 100 [deg.] C for a time sufficient for the complete disappearance of the bromine vapors in the free space above the surface of the solution (2 to 5 hours). Brominated acid hydrazine sulfate is then added to the oleum solution; the mixture is brought to 100 [deg.] - 145 [deg.] C with stirring until the end of the polycondensation and the formation of a polyoxydiazole solution having the required viscosity which is used after dilution with 94-96% sulfuric acid, filtration and degassing for fiber extrusion.

  
Polyarylene-oxadiazoles-1,3,4 containing amino-aromatic groups and azo groups are obtained by proceeding as follows. 20-45% oleum, hydrazine sulfate, an aryl acid are placed in a reactor.

  
 <EMI ID = 30.1>

  
liquids as well as an addition of 5-amino-isophthalic acid or <EMI ID = 31.1>

  
diluted with 95 -96% sulfuric acid to a concentration of 3 to 6%, filtered and used for spinning

  
 <EMI ID = 32.1>

  
ques / oleum varies in 1/5 and 1/10. The ratio of arylene dicarboxylic acid / hydrazine sulfate is equimolar. However, in the event that a polymer of a sufficiently high viscosity does not form, in particular in the case of strong additions of 5-amino-isophthalic acid, it is recommended to take an excess of hydrazine sulfate in an amount not not exceeding
20% of the stoichiometric proportion.

  
Fibers are prepared from modified 1,3,4-polyaryleneoxadiazoles by proceeding as follows. After polycondensation of hydrazine sulphate on acids

  
 <EMI ID = 33.1>

  
and mixed with concentrated sulfuric acid until a solution having the required kinematic viscosity is formed. The mixture is homogenized by stirring, the resulting solution is filtered through an acid resistant cloth and released from included gases by vacuum treatment. The polyoxadiazole solution obtained is spun into the fiber using an aqueous solution of sulfuric acid with a concentration of 30 to 55% as a precipitation bath. The unwashed and freshly spun fiber is subjected to a plasticizer drawing in air or in a bath of aqueous sulfuric acid at a concentration of 10.

  
70% taken in a ratio of 1/2 to 1/6 and washed with water to free it from sulfuric acid and then dried. The fiber is reinforced by stretching in a heated tube

  
 <EMI ID = 34.1>

  
unmodified based on terephthalic acid and / or acid

  
 <EMI ID = 35.1>

  
a hot-drawn polyoxadiazole fiber made from a mixture of 90 mole% terephthalic acid and 10 mole% 5-amino-isophthalic acid is characterized by a number of flexures

  
 <EMI ID = 36.1>

  
polyoxadiazole obtained from azobenzene-dicarboxylic-4,4 'acid is characterized by a limit number of double flexures> 65,000. Tested under identical conditions, the unmodified polyoxadiazole fibers only have a limit number of double bends of 4000 to 5000.

  
Polyoxadiazoles containing residues of 5-amino-isophthalic acid are also of interest given the possibility of various chemical modifications on diazonium groups which the aminoaromatic groups of the polymer can give by diazotization under heterogeneous conditions or else by solution in concentrated sulfuric acid.

  
The azo groups contained in the 1,3,4-polyaryleneoxadiazoles give them a color which varies according to the content of the groups. In this connection it should be noted that the polyoxadiazoles; containing azo groups are suitable for spinning colored fibers (orange, yellow, red) the coloring of which retains an almost invariable liveliness under the prolonged effects of light or bad weather. Other characteristics and advantages of the invention will be better understood on reading the following description of several concrete embodiments.

Example 1

  
24.0 parts by weight of terephthalic acid are placed in a reactor, equipped with a mechanical stirrer, with a sensor (absorber) of gaseous sulfuric anhydride provided with concentrated sulfuric acid and with a heating device. , 8.6 parts by weight of KBr (KBr / terephthalic acid molecular ratio:

  
 <EMI ID = 37.1>

  
iodine deral. The mixture is brought with stirring at 55 [deg.] - 65 [deg.] C for three hours until the disappearance of the bromine vapors in the free chamber of the reactor. 19.6 g of hydrazine sulfate is then added to the solution in brominated acid oleum.
(excess of 4% by weight of the stoichiometric amount) and the whole is heated to 120-140 [deg.] C with stirring for 4 hours. A thick yellow solution of polyoxadiazole is obtained, which is used for the spinning of self-extinguishing fibers.

  
Examples 2 to 9

  
Polyarylene-oxadiazoles-1,3,4 fibrogens, self-extinguishing, are prepared according to the same scheme as in the previous example, but using other monomers or

  
by taking the starting reagents in other reports. The conditions for the preparation of these polymers are summarized in

  
Table 1 below.

Example 10

  
We place in a polycondensation reactor
15.8 parts by weight of terephthalic acid, 0.91 parts by weight of 5-amino-isophthalic acid, 91 parts by weight of 40% oleum and 13.6 parts by weight (5% excess) of hydrazine sulfate . This mixture is brought to a temperature of 130-135 [deg.] C, with stirring, for 4 hours. A thick light brown solution of polymer suitable for spinning is obtained. This polymer contains amino-aromatic groups, the presence of which can be observed by diazotization of the polymer and by coupling with various azo compounds.

  
The process according to the invention for the preparation of polyoxadiazole fibers is economical and simple from the point of view of industrialization since it uses for spinning fibers polymer solutions obtained by an uncomplicated process from relatively inexpensive reagents as well as with Apparatus commonly employed for spinning thermostable fibers from solutions of polyheteroarylene polymers.

  
Polyoxadiazoles and polyoxadiazole fibers based on terephthalic acid and / or isophthalic acid with a bromine content of at least 5-8% are self-extinguishing. These processes burn after ignition, but extinguish as soon as they are removed from the flame of a burner.

  
The introduction of bromine reduces the combustibility of the polyarylene-oxadiazoles-1,3,4 while increasing its thermostability. Brominated polyoxadiazole fibers exposed to air, especially at 350 [deg.] C for 50 h, retain 50 - 60% of their initial mechanical strength, while unmodified fibers tested under the same conditions retain only

  
 <EMI ID = 38.1>

  
Unheated brominated polyoxadiazole fibers exhibit a high moisture absorption capacity of up to 16% when the relative humidity of the air is 65%. Such a property of the fiber is of great interest when used for making clothes and undergarments.

  
The flexural strength of polyoxadiazole fibers containing 5-amino-isophthalic acid residues or azobenzene-dicarboxylic-4,4 'acid residues exceeds sensi-

  
 <EMI ID = 39.1>

Example 11

  
The polycondensation of hydrazine sulfate is carried out, according to the previous example, on mixtures of terephthalic acid / 5-amino-isophthalic acid, taken in molecular ratios of 90/10 and 80/20, as well as on a mix of

  
70 mole% terephthalic acid, 20 mole% isophthalic acid and 10 mole% 5-amino-isophthalic acid. In all cases, solutions of pdymers suitable for spinning are obtained.

Example 12

  
We place in a polycondensation reactor
206.0 parts by weight of 30% oleum, 13.0 parts by weight of hydrazine sulfate and 27.0 parts by weight of azo-

  
 <EMI ID = 40.1>

  
two hours shaking. A thick, dark cherry-colored solution of a polymer is obtained which precipitates when poured into water in the form of threads.

Example 13

  
As in the previous example, the polycondensation of hydrazine sulfate is carried out on a mixture of

  
80 mole% terephthalic acid and 20 mole% azobenzene-dicarboxylic acid-4,4 ', the ratio of hydrazine sulfate /

  
 <EMI ID = 41.1>

  
mixture of azobenzenedicarboxylic acid. -4,4 '/ terephthalic acid / isophthalic acid taken in molecular proportions

  
of 10/70/20, in the absence and in the presence of an excess of hydrazine sulfate of 10% by weight relative to the stoichiometric proportion. In all cases, colored solutions are obtained

  
of polymers suitable for spinning.

Example 14

  
A 6.5% solution of poly-paraphenylene-oxadiazole-1,3,4 is filtered through a fabric resistant to <EMI ID = 42.1> <EMI ID = 43.1>

  
in concentrated sulfuric acid (94-98%) to obtain

  
 <EMI ID = 44.1>

  
in a precipitation bath consisting of 54% sulfuric acid. The freshly spun fiber is subjected to drawing

  
 <EMI ID = 45.1>

  
the

  
 <EMI ID = 46.1>

  
 <EMI ID = 47.1>

  
39 gf / tex for an elongation of 3.4%. This fiber is very markedly self-extinguishing. Its heat stability evaluated by the rate of retention of the breaking strength expressed in% of the initial strength after heating

  
in air at 350 [deg.] C, has the following values: after 10 hours-96%;

  
 <EMI ID = 48.1>

  
30%. The moisture content of the initial fiber, in an atmosphere of 65% humidity and at 20 [deg.] C, is 16.8%, the moisture content of the hot-drawn fiber is equal in same conditions at 4.5%.

Example 15

  
The fiber is spun as in the previous example. The poly-para-phenylene-oxadiazole-1,3,4 used contains 9.73% bromine, and its specific viscosity is 3.4. The concentration of the spinning solution is 4.1%. The plasticizer stretch ratio is 1 / 3.4, the hot stretch ratio

  
at 400 [deg.] C is 1 / 1.7. The final fiber is self-extinguishing. Its thermostability at 350 [deg.] C has the following values after exposure to air: after 25 hours-79%; after 50 hours -59%. The tensile strength of the fiber is 37 gf / tex for an elongation of 3.8%.

  
 <EMI ID = 49.1>

  
The fiber is spun as in Example 14.

  
As a spinning solution we take a solution

  
 <EMI ID = 50.1>

  
by polycondensation of tallow alie hydrazine on diphenylene-dicarboxlic acid-4,4 ', with a bromine content of 15.2% and a specific viscosity of 1.9. A die with 300 holes of 0.08 mm in diameter is used to spin the fiber. The precipitation bath consists of 54% aqueous sulfuric acid. The freshly formed fiber is subjected to air stretch plasticizer at a ratio of 1 / 2.0. The fiber released from acid is stretched

  
 <EMI ID = 51.1>

  
1 / 1.2. The fiber obtained has a tensile strength of 20 gf / tex for an elongation of 4.6%. This fiber is clearly self-extinguishing. Its thermostability at 350 [deg.] C is 86% (duration of exposure to air of 25 hours).

Example 17

  
The fiber is spun in a manner analogous to that of Example 14 &#65533; As the spinning solution, a 4.2% solution in sulfuric acid of a polyoxadiazole obtained by polycondensation of hydrazine sulfate on sulfodiphenylene-dicarboxylic acid-4,4 'at a content of in bromine of 10.4% and a specific viscosity of 0.97. The precipitation bath consists of 55% sulfuric acid. The plasticizer stretching is carried out in a ratio of 1 / 1.9. The fiber freed by washing with sulfuric acid and dried is passed through a heater at 450.degree. C., without drawing. The fiber obtained

  
has a tensile strength of 12.5 gf / tex for an elongation of 9.7%. This fiber is clearly self-extinguishing. Its thermostability at 350 [deg.] C is 98% (when exposed to air for 25 hours).

  
 <EMI ID = 52.1>

  
We. employs as a spinning solution a

  
 <EMI ID = 53.1>

  
 <EMI ID = 54.1>

  
95 mole% terephthalic acid and 5 mole% 5-amino-isophthalic acid. The specific viscosity of the solution of 1 g of

  
 <EMI ID = 55.1>

  
20 [deg.] C is equal to 4.4. The concentration of the solution is 5%.

  
The spinning of the solution of co-poly-oxadiazole is carried out.

  
 <EMI ID = 56.1>

  
300 holes of 0.08 mm in diameter. The precipitation bath

  
consists of 54% sulfuric acid. We submit the fiber

  
 <EMI ID = 57.1>

  
from 1 / 3.0 to 1/3, 5.water enclave to get rid of acid

  
 <EMI ID = 58.1>

  
 <EMI ID = 59.1>

  
an elongation of 6%. The number of double flexures of the fiber

  
 <EMI ID = 60.1>

  
DP-15 Shopper is 52,000.

Example 19

  
As the spinning solution, a 4% solution in sulfuric acid of polyoxadiazole obtained by polycondensing hydrazine sulfate with azobenzene-dicarboxylic acid-4,4 'is used. The specific viscosity of the polymer is 4.8. As the precipitation bath, 52% aqueous sulfuric acid is used. The air plasticizer stretch ratio is 1/4. The draw ratio at 400 [deg.] C is 1 / 1.5. The resulting dark cherry-colored fiber has a breaking strength of
52 gf / tex for an elongation of 6%. The number of double flexes of the fiber to failure under a load of 5 kgf / mm <2> is 65,000.

  
 <EMI ID = 61.1>

  
The fiber is spun as in the previous example, with the sole difference that a co-pdlyoxadiazole obtained by starting from a mixture of 80 mole% of terephthalic acid and 20 moles is used as polymer. % azobenzene-dicarboxylic acid-4,4 '. The scarlet fiber obtained has a tensile strength of 43 gf / tex for an elongation of 4%. The number of double flexures of the fiber under a load of 5 kgf / mm <2> is 9000.

  
Examples 21 to 34

  
In the examples cited, the spinning of the fibers

  
from the modified polyarylene-oxadiazole-1,3,4 spinning solutions and subsequent treatments of the fibers formed

  
are carried out by varying the conditions within wide limits in order to obtain the tolerated limit values of the parameters of preparation of the fibers. Table 2 below summarizes

  
the characteristics of the initial spinning solutions as well as the conditions of their transformation into fibers. The fibers formed under the conditions cited are suitable for processing in textile establishments.

  
Of course, various modifications can be made by those skilled in the art to the devices or methods which have just been described by way of non-limiting examples without departing from the scope of the invention.

  

 <EMI ID = 62.1>


  

 <EMI ID = 63.1>


  

 <EMI ID = 64.1>
 

  

 <EMI ID = 65.1>


  

 <EMI ID = 66.1>
 

  

 <EMI ID = 67.1>


  

 <EMI ID = 68.1>


  

 <EMI ID = 69.1>
 

CLAIMS

  
 <EMI ID = 70.1>

  
terized in that their macromolecule consists of the following units:

  

 <EMI ID = 71.1>


  
or d.phenylene

  
in which R 'represents a phenylene / radical, and R "represents a bromophenylene or bromodiphenylene radical, R' (Br),

  
meta-amino-phenylene

  

 <EMI ID = 72.1>


  
or an azodiphenylene radical

  

 <EMI ID = 73.1>


  
, the molar content of con-

  
holding a bromophenylene or bromodiphenylene radical being equal to a maximum of 80%, the molar content of units containing a meta-aminophenylene radical being equal to a maximum of 25% and the molar content of units containing the azodiphenylene radical
-4.4 'being equal to a maximum of 100%.

  
2. Process for the preparation of polyarylene-oxadia-


    

Claims (1)

zoles-1,3,4 according to Claim 1, characterized in that the polycondensation of hydrazine sulfate is carried out on isophthalic acid and / or on terephthalic acid, at a temperature of 85 [deg. ] at 145 [deg.] C in oleum, in the presence of an additive such as salts of hydrobromic acid, amino5-isophthalic acid or azobenzenedicarboxylic acid-4,4 '. 3. Method according to claim 2, characterized in that the hydrazine sulfate is used in an excess of up to 20% of the stoichiometric amount. 4. Method according to claim 2, characterized in that in the case of the use of a hydrobromic acid salt, the reactions are carried out in the presence of an addition <EMI ID = 74.1> hydrobromic. 5. Method according to claim 4, characterized in that the molar ratio of hydrobromic acid salt / aromatic dicarboxylic acid or mixture of aromatic dicarboxylic acids is within the limits of 0.1 / 1 to 1.5 / 1 respectively. . 6. Process according to claim 2, characterized in that the hydrobromic acid salt is introduced before the polycondensation in the suspension of oleum and of the aromatic dicarboxylic acid or of the mixture of aromatic dicarboxylic acids, and in bringing the mixture obtained to a temperature of 50 to 100 [deg.] C, then adding the sulfate <EMI ID = 75.1> 7. Process for the preparation of fibers by spinning from spinning solutions in sulfuric acid, containing modified polyarylene-oxadiazoles-1,3,4, by carrying out an aqueous sulfuric acid precipitation bath with subsequent increase in the strength of the freshly formed fiber by hot drawing, characterized in that as spinning solutions in sulfuric acid, solutions containing polyarylene-oxadiazoles-1,3,4 according to claim 1 and, as a precipitation bath, a 30-35% solution of sulfuric acid, with subsequent plasticizing stretching of the freshly spun fiber in a ratio of 1/2 to 1/6 and strengthening by stretching at a temperature of 350 [ deg.] at 450 [deg.] C. 8.Modified 1,3,4-polyarylene oxadiazoles, their preparation process and the fiber preparation process <EMI ID = 76.1> <EMI ID = 77.1>