JPS5839861B2 - polyamide sewage - Google Patents

Description

Detailed Description of the Invention The present invention provides molded products such as fibers and films that are suitable for forming by spinning or film forming, have excellent properties such as heat resistance and high Young's modulus, and have excellent fluidity and stability. Concerning superior polyamide solutions.

Polyamides with aromatic rings oriented coaxially or parallel axes (e.g. poly-p-phenylene terephthalamide, poly-p-
benzamide, etc.) and certain solvents (e.g. concentrated sulfuric acid, oleum, protic acids such as hydrofluoric acid, chlorosulfonic acid, bromsulfonic acid, methanesulfonic acid, etc.; organic polar solvents such as amide-based or urea-based solvents containing salts) ) It is already known that solutions with higher Young's modulus exhibit optical anisotropy and can be used for producing high Young's modulus fibers.

(See, for example, US Pat. No. 3,671,542; US Pat. No. 3,673,143) However, such polyamide solutions have various problems.

In other words, when a solution is made by mixing a polyamide with aromatic rings oriented coaxially or parallel axes with a protic acid such as sulfuric acid or fuming sulfuric acid, it exhibits optical anisotropy within a certain concentration range and the viscosity of the solution decreases. do.

The concentration range of a solution exhibiting this optical anisotropy varies depending on the purchase of the polymer, the type of solvent, and the temperature.

In order to obtain a solution suitable for use as a spinning dope with excellent fluidity and spinnability, it is common to lower the concentration or raise the temperature, but if the concentration is lowered, there will be economic disadvantages. Instead, the solution viscosity may increase on the contrary because it approaches the region of an optically isotropic solution.

Furthermore, when the temperature of the solution is raised, amide bonds in the polymer chains are likely to be broken, accelerating a decrease in the degree of polymerization, and it is expected that this will cause a decrease in the physical properties of the molded product.

When using organic solvents such as amide-based or urea-based solvents containing salts, the dissolution rate of the polymer is extremely slow and it takes a long time to reach dissolution equilibrium, resulting in many problems such as moisture absorption during that time. In many cases, the solvent's dissolving power cannot be fully utilized.

It is possible to increase the temperature to increase the dissolution rate, but this does not give good results because the crystallization of the polymer is promoted at the same time.

On the other hand, polymers containing heterocycles such as polybenzoxazole and polybenzimidazole have superior characteristics such as superior heat resistance and good hygroscopicity compared to ordinary polyamides, but they have extremely low affinity for solvents and Even when a low concentration solution is obtained, the viscosity of the solution becomes too high, making it difficult to obtain molded articles such as fibers and films.

The present inventors have solved these drawbacks of solutions of polyamides having coaxially or parallelly oriented aromatic rings, improved the solubility of polymers containing heterocycles, and achieved fluidity and stability at high concentrations. As a result of extensive research in order to obtain a solution excellent in The present invention was completed based on the discovery that it exhibits optical anisotropy, has excellent fluidity and stability at high concentrations, and can be used for spinning and film formation.

That is, the present invention provides the following general formula (I) [Here, X represents one of O, S, and NH.

Ar'' and Ar2 represent divalent aromatic rings oriented along coaxial or parallel axes.

] A polyamide polymer containing at least 70 mol% or more of repeating units represented by the formula ** and sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, furomsulfonic acid,
The optically anisotropic solution consists essentially of at least one protonic acid selected from metal sulfonic acid and hydrogen fluoride.

The polymer used in the present invention has general formula (I) [Here, X represents one of o, S, and NH.

Ar' and Ar2 represent divalent aromatic rings oriented along coaxial or parallel axes.

] refers to a polymer containing at least 70 mol% of repeating units.

Examples of substituents used for Ar1 and Ar2 include lower alkyl dichromes such as methyl and ethyl, nitrogen such as bromine; ★★alkoxy such as methoxy and ethoxy; groups such as nitro and cyano.

Specific examples of the repeating unit represented by the general formula (I) include polyamide benzoxazoles such as , polyamide benzimidazoles such as , and polyamide benzthiazoles such as .

The polymer used in the present invention may contain 30% or less of repeating units other than those of general formula (I).

Specific examples of such repeating units include oxadiazoles, other polyimides, polyamide-imides, polyesters, polyamide esters, and polkina.
zolindione, polyindolone, polythiadiazole,
Examples include polytriazole, polyquinoxaline, polyimidazopyrrolone, polyquinazolone, and the like.

It is necessary that the degree of polymerization of such a polymer is above a certain value.

The required degree of polymerization varies somewhat depending on the type of polymer, but ηi
nh (intrinsic viscosity at 30°C of a solution of 0.51 of the polymer dissolved in 100 ml of concentrated sulfuric acid) is preferably 1.0 or more, and more preferably 30 or more.

That is, in the case of a polymer having ηinh of 1,0 or less, the solution thereof often does not exhibit optical anisotropy.

Methods for obtaining such polymers include polycondensation of a diamine containing a benzoxazole or benzimidazole ring and a dicarboxylic acid cybaride; and polycondensation of a diamine having OH, SH, or NH2 groups as a substituent and a dicarboxylic acid cybaride. There is a method of dehydrating and ring-closing the obtained polyamide.

The polycondensation of diamine and dicarboxylic acid halide is preferably carried out by low-temperature solution polymerization in an amide or urea solvent.

As a matter of course, the solvent used in the present invention must be a solvent that dissolves the polymer.

Examples of such solvents include protic acids such as sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, bromesulfonic acid, methanesulfonic acid, and hydrogen fluoride.

The polymer concentration in the optically anisotropic polymer solution according to the present invention varies depending on the type of polymer and the combination of solvent,
When the solvent is sulfuric acid, oleum, etc., the polymer concentration must exceed about 10% by weight.

Otherwise, the polyamide solution obtained will exhibit optical anisotropy and will have poor spinnability.

According to conventional knowledge, the property of optical anisotropy has been observed only in solutions of polymers that have a combination of amide bonds (-C-NH-) and skeleton elements with coaxial or parallel axis orientation. Since the polymer in the present invention contains a 5-membered heterocycle such as benzoxazole or benzimidazole as described above, the skeleton structure is obviously non-coaxial and non-parallel oriented.

Nevertheless, it is surprising that the polymer solutions of the present invention exhibit optical anisotropy.

Note that the optically anisotropic solution as used in the present invention refers to a solution that exhibits a birefringence phenomenon when the solution is viewed with a polarizing microscope.

A polymer solution that provides such an optically anisotropic solution is characterized by a maximum in polymer concentration and solution viscosity.

That is, at low concentrations, the solution is optically isotropic and the solution viscosity increases with the concentration, but at a certain concentration or higher, the solution becomes optically anisotropic and the solution viscosity decreases.

Methods for obtaining the polymer solution in the present invention include a method of mixing a pre-isolated polymer powder with a solvent, and a method of directly obtaining the desired polymer solution by carrying out a polymerization reaction to obtain such a polymer in a solvent. , after polymerization is carried out in solution,
There is a method of neutralizing part or all of the generated hydrogen chloride with a metal hydroxide, oxide, carbonate hydride, etc. to obtain a solution containing a metal salt and a polymer.

The polyamide solution of the present invention has good fluidity and spinnability, and can be used to produce excellent fibers or films by extruding it into an aqueous coagulation bath through a spinning hole or slit, for example.

Specific examples of the present invention will be illustrated below with reference to Examples.

In the examples, ηinh means 0.5 f of polymer in 100 g of concentrated sulfuric acid.
The intrinsic viscosity at 30℃ of a solution dissolved in m1★
It is ★.

Example 1 Polyamide benzoxazole (ηin
h 7.72 ) 2.21 and 100% sulfuric acid 7.8i were vigorously mixed at 0° C., and then the temperature was returned to room temperature to obtain a solution with excellent fluidity and stringability.

When a polish was added to this solution, a striped turbidity appeared, and when a part of this solution was observed under a polarizing microscope, it showed birefringence, which revealed that this solution was an optically anisotropic solution.

When this solution was heated to about 80° C., the fluidity and spinnability of the solution were further improved, and the optical anisotropy was also maintained.

The strength of the filament obtained by extruding an optically anisotropic solution at 80°C into water through a nozzle is T ('?/de)/
Elongation E (%)/Young's modulus Mi (?/de) are each 1
It was 3.2/4°0/420.

Comparative example 1 Poly(p-phenylene terephthalamide) *.

*(η1nh5.41) After vigorously mixing 22P and 78 g of ioo% sulfuric acid at 0°C, the system remained dry and heterogeneous even after the mixture was returned to room temperature.

This mixture was further heated to 80°C, but the appearance of the mixture did not change much, and only after heating to 130°C did it become fluid.
Both stringability improved.

However, the viscosity of this solution gradually decreased, and the degree of polymerization of the polymer decreased significantly.

Example 2 Polyamide benzoxazole (ηinh 7.72 ) represented by the same formula as in Example 1 and 100% sulfuric acid were dissolved in the same manner as in Example 1 to give various concentrations.

The viscosity of each solution at 25°C was measured by a falling ball method.

A portion of each solution was also observed with a polarizing microscope to determine optical isotropy and anisotropy.

These results are shown in Table 1.

Example 3 (m/n=5o/2o) Aromatic polyamide benzoxazole represented by the above formula (
77inh 5.66 ) in 102% sulfuric acid at 0℃ for 15 minutes.
wt% dissolved.

The obtained solution had good fluidity and stringability at room temperature, and exhibited optical anisotropy.

★★ηinh after keeping this solution at 80℃ for 3 hours
was 5.50.

The T/E/M i of filaments obtained by extruding a solution at 80°C through a nozzle into cold water is 12.
It was 1/3.2/390.

Example 4 Polyamide benzimidazole (yi
inh 4.77) was dissolved in 18% by weight in 100% sulfuric acid at 0°C.

The obtained solution exhibits optical anisotropy※※ and can be heated from room temperature to 80℃
It showed good fluidity and stringability.

Example 5 Polyamide benzimidazole (η1n
h6.11) was dissolved in 101% sulfuric acid at 0°C at various concentrations.

A solution having a polymer concentration in the range of 12% to 30% by weight exhibited optical anisotropy at room temperature to 80°C, and had excellent fluidity and stringability.

Claims (1)

[Claims] 1 The following general formula (I) [In the foreplant, X is 0. 10 weight percent of a polyamide polymer containing at least 70 mol% of repeating units represented by either S or NH, and Ar 1, Ar'' represents a divalent aromatic ring oriented along a coaxial or parallel axis. % and at least one protonic acid selected from sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, bromesulfonic acid, metalsulfonic acid and hydrogen fluoride.