JPS6017227B2 - Method for producing aromatic polyamide solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aromatic polyamide solution, and more particularly to a method for producing an aromatic polyamide solution having excellent filtration properties.

Molded products such as woven chicks, films, and pulp particles with excellent heat resistance are produced from aromatic polyamide solutions.These molded products not only have excellent heat resistance, but also have flame resistance, chemical resistance, and high temperature resistance. It has excellent morphological stability, thermal decomposition resistance, electrical properties, mechanical properties, etc., and is extremely valuable industrially.

It is industrially advantageous to produce the aromatic polyamide solution by a low-temperature solution polymerization method in which an aromatic diamine and an aromatic dicarboxylic acid chloride are reacted in an amide-type polar solvent. The reason for this is that in this case, there is no need for the troublesome process of isolating, washing, drying, and redissolving the produced polymer in a solvent for producing molded products. This is because production can be performed using a common solvent. That is, after reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in an amide-type polar solvent, the hydrochloric acid produced by the reaction (which exists as a hydrochloride in an amide-type solution) is mixed with ursium hydroxide, calcium oxide, calcium carbonate, lithium hydroxide,
When neutralization is performed with an inorganic alkali such as lithium carbonate, magnesium hydroxide, or magnesium carbonate, the generated calcium chloride, lithium chloride, etc. are soluble in the solvent and have the ability to increase the solubility of the polymer, so neutralization is completed. The resulting solution can be used as is for producing molded products.

However, although this method is economically extremely advantageous compared to the method of once isolating the polymer, it has the disadvantage that the polymer solution has poor tear resistance during the furnace filtration process that is performed prior to manufacturing molded products. has.

Generally, during neutralization, inorganic alkali is added in a substantially equivalent amount or slightly in excess of hydrochloric acid, but after most of the hydrochloric acid has been neutralized, a small amount of hydrochloric acid remains and a small amount The reaction with a solid inorganic alkali is very slow, and the viscosity of the reaction system is very high. It appears to be.

Alternatively, after most of the hydrochloric acid has been neutralized, the neutralization reaction occurs only on the surface of the collective inorganic alkali, and as a result, the water molecules produced form microgels with the unreacted inorganic alkali as cores. It may be for a reason. Regardless of the reason, if the amount of inorganic alkali added is reduced by an equivalent amount relative to hydrochloric acid in order to improve the permeability of the aromatic polyamide solution, the residual hydrochloric acid will significantly corrode the equipment, and therefore There is a problem in that if a device is to be made of a material that is corrosion resistant, the device must be extremely expensive. Therefore, in general, an amount of inorganic alkali that can completely neutralize the hydrochloric acid is added to suppress corrosion of the equipment, but in this case, as mentioned above, the aromatic polyamide solution has extremely poor permeability. Therefore, there is a problem in that the frequency of replacing or cleaning the furnace material increases significantly. The present inventors produced an aromatic polyamide solution by reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in an amide-type polar solvent, and then neutralizing the hydrochloric acid produced by the reaction with an inorganic alkali river. The present invention was arrived at as a result of extensive research into finding and developing a method for producing a polymer solution that is completely neutralized and has good filtration properties. .

That is, in the present invention, an aromatic polyamide solution is produced by reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in a polar amide type solvent, and then neutralizing the resulting inorganic alkali hydrochloric acid with IJI. On this occasion,
A neutralization reaction is carried out by adding an inorganic alkali that produces a solvent-soluble salt upon neutralization in an amount that is at least 90% of the equivalent of the existing hydrochloric acid, but less than the equivalent, and then ammonia is added to neutralize the remaining hydrochloric acid. This is a method for producing an aromatic polyamide solution, which is characterized in that the aromatic polyamide solution is hydrated.

According to the method of the present invention, all of the hydrochloric acid generated by the polymerization reaction is neutralized, so there is no fear of significant corrosion of equipment based on hydrochloric acid, and the phenomenon of deterioration of reactor properties, which is thought to be caused by the inorganic alkali of the hydrochloric acid reaction, is eliminated. Therefore, the frequency of replacing the furnace material in the furnace process is reduced, and work efficiency is significantly improved.

Examples of aromatic diamines used in the present invention include m-phenylene diamine, P-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'
Examples include -diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminodiphenyl sulfone, but these diamines may have substituents that do not inhibit the reaction.

Furthermore, examples of the aromatic dicarboxylic acid chloride used in the present invention include isophthalic acid chloride,
Examples include terephthalic acid chloride, 4,4-diphenyldicarboxylic acid chloride, and 2,6-naphthalenedicarboxylic acid chloride, but these acid chlorides may have a substituent that does not inhibit the reaction. The present invention is also applicable to the case where an aromatic copolyamide is produced using two or more kinds of aromatic diamines and/or aromatic dicarboxylic acid chlorides. Furthermore, monomers other than aromatic diamines and aromatic dicarboxylic acid chlorides, such as piperazine, 2,5-dimethylpiverazine, hydrazine salts, hexahydrolysophthalic acid chloride, hexahydroterephthalic acid chloride, other aliphatic diamines, and fatty acids The present invention is also applicable to the production of a copolymer containing a small amount of group dicarboxylic acid chloride or the like.

As the polar amide type solvent used in the present invention,
Examples include dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, tetramethylurea, and hexamethylphosphoramide.

As for the inorganic alkali used in the present invention, it is necessary that the salt produced by neutralization is soluble in the above-mentioned polar amide type solvent, and it is desirable that the inorganic alkali increases the solubility of the aromatic polyamide ( Examples of such salts are described, for example, in Samurai Publication No. 35-16027.

), Examples of such inorganic alkalis include calcium hydroxide, calcium oxide, calcium carbonate, lithium hydroxide, lithium carbonate, magnesium hydroxide, and magnesium carbonate. In order to produce an aromatic polyamide solution by the method of the present invention, first, an aromatic diamine and an aromatic dicarboxylic acid are subjected to a polymerization reaction in a gutter amide type solvent.

The polymerization reaction can be carried out, for example, by the method described in Japanese Patent Publication No. 35-1439. In the present invention, an inorganic alkali is then added to the reaction mixture after the polymerization is completed. If the amount of inorganic alkali added is less than 90% of the equivalent amount of hydrochloric acid present in the reaction mixture, the subsequent neutralization with ammonia will not improve the filterability. On the other hand, the amount of inorganic alkali added is
Approaching an amount equal to the equivalent amount of hydrochloric acid present tends to reduce the filtration properties of the polymer solution, as mentioned above. Therefore, the amount of inorganic alkali added needs to be at least 90% of the equivalent amount of hydrochloric acid present, but less than the equivalent amount.
Particularly preferred are amounts in the range % to 99.8%. The inorganic alkali may be added alone, but in order to add it as uniformly as possible, it is preferable to add it after being dispersed in a polar amide type solvent.

The neutralization reaction due to the addition of an inorganic alkali is substantially completed by allowing the reaction to proceed for 1 to 5 hours under continuous conditions. In the present invention, it is necessary to then add ammonia to neutralize the remaining hydrochloric acid. As for the form of ammonia to be added, ammonia itself can be added, but from the point of view of ease of handling, a solution of ammonia dissolved in a polar amide solvent, an aqueous ammonia solution, or a solution of an aqueous ammonia solution mixed in a polar amide solvent are recommended. It is preferable to use Regarding the amount of ammonia added, even if excess ammonia exists, it will not adversely affect the furnace stability of the solution, and since it can be easily removed in the defoaming process, it will not adversely affect the molding process. Nor. Therefore, ammonia can be added in a substantially equivalent amount or more than the equivalent amount to the remaining hydrochloric acid, but in consideration of the dissipation of ammonia, it is particularly preferable to add the equivalent amount or more.

However, since there is no particular need for excess ammonia to be present, the object of the present invention can be achieved by adding at most an amount of 1M or less equivalent to the amount of residual hydrochloric acid. After adding ammonia, the mixture is heated for 1 to 3 hours to neutralize all of the hydrochloric acid, and a solution with good filtration properties is obtained. The aromatic polyamide solution obtained by the method of the present invention is suitably used for producing molded products such as fibers, films, and pulp particles.

The present invention will be explained in more detail below with reference to Examples.

Note that "parts" in the examples mean "parts by weight." Comparative Example 1 N-methylpi.

Lydon 5000 Anchor 1 com-Phenylenediamine 416
After melting 2 parts at room temperature, cooling to -5°C,
Next, add 7814 parts of terephthalic acid chloride to a temperature of 4.
The viscosity was gradually added so as not to exceed 0.000, and the viscosity was continued for 32 minutes after addition of the acid chloride, and the viscosity reached the required value. Next, a solution containing 291 parts of calcium hydroxide with a purity of 98% (which corresponds to an equivalent amount of hydrochloric acid produced in polymerization when purity is taken into account) and 550 parts of N-methylpyrrolidone was added. Neutralization was carried out for 2 hours. The obtained polymer solution was slightly cloudy, and when quantitative furnace heating was carried out using a stainless steel net of 1480 mesh with a furnace overpressure of 50 mm at a speed of 800 mm/min, the furnace overpressure increased to 100 k9 in about 1 minute. It was difficult to filtrate the solution after rising to 1/2 mL, and the solution had very poor filtration properties.

Comparative Example 2 After polymerization was carried out in the same manner as in Comparative Example 1, 2855 parts of calcium hydroxide with a purity of 98% was added to the reaction solution (corresponding to an amount 1.9% smaller than the equivalent amount of hydrochloric acid present in consideration of purity). A solution prepared by dispersing 550 ml of N-methylpyrrolidone was added, and the mixture was heated for 2 hours for neutralization.

When the obtained polymer solution was subjected to furnace heating in the same manner as in Comparative Example 1, the furnace filtration strength was 100k after 18 days.
9/ The reactor was no longer able to operate the reactor.

In order to examine the corrosive properties of this solution, a portion of it was applied to a mirror-finished SUS30 plate made of 130
After drying with hot air at a temperature of The corrosion spread as the polymer solution was repeatedly applied and dried, and the mirror surface gradually turned white. Comparative Example 3 A polymer was prepared in the same manner as in Comparative Example 2, except that 2,825% of calcium hydroxide with a purity of 10% was used (corresponding to an amount 2.9% less than the equivalent amount of hydrochloric acid present, considering the purity). A solution was obtained.

The furnace susceptibility of the obtained polymer solution was even better than that of Comparative Example 2, and it could be heated for 27 cycles before reaching the point of failure.

However, the corrosivity of this polymer solution was even more severe than that of Comparative Example 2, and a large number of pits occurred after just one application and drying, and the mirror surface turned white.

Example 1 After polymerization was carried out in the same manner as in Comparative Example 1, 2855 parts of calcium hydroxide with a purity of 1% (considering the purity, corresponds to an amount 1.9% smaller than the equivalent amount of hydrochloric acid present)
The first neutralization was carried out by adding a solution in which 550% of N-methylpyrrolidone was dispersed and stirring for 2 hours.

Subsequently, a solution prepared by dissolving 250 parts of 28% aqueous ammonia (there is 2.8 times the amount of ammonia as the equivalent of hydrochloric acid remaining in the first neutralization) in 1300 parts of N-methylpyrrolidone was added. Then, Tanazusa was further applied for 1 hour to perform secondary neutralization. When the obtained polymer solution was subjected to furnace filtration in the same machine as in Comparative Example 1, it took 19 weeks before the furnace could no longer be filtrated.

In addition, a polymer solution was applied to a mirror plate made of 30 SUS vessels,
Even after repeating the drying corrosion test on the IM team, no pitting rot occurred on the mirror surface. Example 2 2825 parts of calcium hydroxide (corresponding to 2.9% less than the equivalent amount of hydrochloric acid present, taking purity into account)
The first neutralization was carried out by repeating the same operation as in Example 1 except for the addition.

Subsequently, a solution of 25 g of 28% ammonia water (containing 1.8 times the amount of ammonia equivalent to the amount of hydrochloric acid remaining in the first neutralization) dissolved in 130 g of N-methylpyrrolidone was added. Then, Nada Azusa was carried out for 1 hour to perform the second neutralization. When the obtained polymer solution was subjected to filtration in the same manner as in Comparative Example 1, it was possible to filtrate the polymer solution for 28 hours before the filtration became impossible.

Even when a corrosion test in which a polymer solution was applied to a mirror plate made of SUS304 and dried was repeated 10 times, no pitting occurred on the mirror surface.

Example 3 A solution of 6327 parts of m-phenylenediamine dissolved in 4200 miyako dimethylacetamide at room temperature was -
After cooling to 5°C, 11,880 parts of isophthalic acid chloride was gradually added so that the inner stripe did not exceed 60q0, and stirring was continued for another 40 minutes. (according to the amount equivalent to 3.0% less than the equivalent amount of hydrochloric acid present) in a dimethylacetamide solution of 550 foundations was added, and the mixture was heated for 2 hours to perform the first neutralization. went.

Subsequently, 40 parts of 28% ammonia water (there is 1.8 times the amount of ammonia as the equivalent of hydrochloric acid remaining in the first neutralization)
A solution prepared by dissolving 200 parts of dimethylacetamide was added, and the mixture was left to stand for 1 hour for secondary neutralization. When the filtration property of the obtained polymer solution was measured in the same manner as in Comparative Example 1, the solution could be passed through the oven for 31 hours before it became impossible to pass through the oven, and the filtration property was good.

Further, a corrosion test using a mirror plate made of SUS30 conductor was repeated 20 times, but no pitting occurred. For comparison, a corrosion test was conducted on a polymer solution obtained by performing only the first neutralization, and pitting was already observed in the first neutralization.

Moreover, the reactability of the obtained polymer solution obtained by neutralizing by adding calcium hydroxide in an equivalent amount to the existing hydrochloric acid was extremely poor. Comparative Example 4 Polymerization was carried out in exactly the same manner as in Example 3, and when adding the neutralizing agent, first a solution prepared by dissolving the same amount of 28% ammonia water as in Example 3 in 200 g of dimethylacetamide was added. A first neutralization was carried out by keeping the light on for one hour, and then a solution of 410 parts of calcium hydroxide (equivalent to the remaining hydrochloric acid) dispersed in 550 parts of dimethylacetamide was added. I spent an hour at a loss.

The resulting polymer solution was turbid, and its permeability was measured in the same manner as in Comparative Example 1, and it was found that the overpressure increased significantly by 0.4 to 0.5 weeks, and could not be permeated. became.

Comparative Example 5 After polymerization was carried out in the same manner as in Comparative Example 1, 2474 parts of calcium hydroxide with a purity of 98% (corresponding to 85% of the equivalent amount of hydrochloric acid present if purity is considered) was added to 500 parts of N-methylpyrrolidone. The first neutralization was performed by adding the dispersed solution and stirring for 1 hour.

Claims (1)

[Claims] 1. After reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in a polar amide type solvent, an aromatic polyamide solution is prepared by neutralizing the hydrochloric acid produced in the reaction with an inorganic alkali. During production, an inorganic alkali that produces a solvent-soluble salt upon neutralization is added in an amount equal to or more than 90% of the equivalent amount of hydrochloric acid present, but less than the equivalent amount to perform a neutralization reaction, and then ammonia is added. A method for producing an aromatic polyamide solution, characterized by neutralizing residual hydrochloric acid. 2. The manufacturing method according to claim 1, wherein the neutralization reaction is carried out by adding an inorganic alkali that produces a solvent-soluble salt upon neutralization in an amount of 95% to 99.8% of the equivalent of the existing hydrochloric acid. 3. The manufacturing method according to claim 1 or 2, wherein the neutralization reaction is carried out by adding an inorganic alkali dispersed in a polar amide type solvent. 4 Claims 1 to 4 in which the remaining hydrochloric acid is neutralized by adding ammonia in an amount equivalent to or more than the remaining hydrochloric acid.
The manufacturing method described in any of paragraphs.