JPS62187729A - Production of aromatic polyamide - Google Patents

Abstract

PURPOSE:To obtain the titled high-quality uniform polymer having a high m.p. and a high degree of polymerization and being excellent in strength, modulus, heat resistance and flame retardancy, by polymerizing p-phenylenediamine with terephthaloyl chloride by using a specified solvent system. CONSTITUTION:CaCl2 preheated, if necessary, to about 200 deg.C is heated for 5hr or longer at 250-500 deg.C in air or an inert gas such as N2 and cooled to about 80 deg.C in an inert gas such as N2 under the exclusion of moisture. The CaCl2 heat-treated under the above-specified conditions is dissolved in an N- substituted solvent (e.g., N-methyl-2-pyrrolidone) so that the concentration may be 0.30-0.90mol/l. About equimolar amounts of p-phenylenediamine and terephthaloyl chloride are dissolved in this solution so that the resulting solution may have a monomer concentration as high as 0.40-0.50mol/l, and the monomers are polymerized at -10-70 deg.C under an applied high shearing force.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to solution polymerization of polyvalent phenylene terephthalamide, and its purpose is to heat-treat calcium chloride used for polymerization under specific conditions to increase the degree of polymerization. The object of the present invention is to provide a method for polymerizing the following polymers.

(Prior art) In order to obtain a polymer with a high degree of polymerization by solution polymerization of polyparaphenylene terephthalamide, it has been found that hexamethyl 7-osphoramide, or a mixed solvent of hexamethyl 7-osphoramide and an organic polar solvent is suitable as a solvent. Are known.

However, since hexamethyl 7-osphoramide is biologically active and its use is not preferred, it has been proposed to use N-substituted carbonamide as the solvent and add calcium chloride to it to obtain a highly polymerized polymer. (Japanese Unexamined Patent Publication No. 109099/1989, Japanese Unexamined Patent Publication No. 1983
-71593).

(Problems to be solved by the present invention) However, in this N-substituted carbonamide calcium chloride system, the degree of polymerization of the resulting polymer is not so high, and it also has the disadvantage that there is large variation between patches. .

On the other hand, the mechanical performance of fibers and films obtained by molding polyvalent phenylene terephthalamide is greatly affected by the degree of polymerization, and in order to obtain good performance, it is necessary to use a polymer with an intrinsic viscosity (ηinh) of 6 or more. There is a strong desire for technology to produce it stably.

For this purpose, it is known that monomers of as high purity as possible should be used, and that the water content of the solvent and calcium chloride should be removed as much as possible to reduce the amount of water to a few hundred ppm or less. It has been difficult to stably produce polymers with a high degree of polymerization.

(Means for Solving the Problems) In view of the above-mentioned shortcomings, the present inventor has developed a polyphenylene terephthalamide based on N-substituted carbonamide calcium chloride with a high degree of polymerization, with less variation in the degree of polymerization. As a result of extensive research on the production method, we surprisingly found that by using calcium chloride heat-treated under certain specific conditions for polymerization, it was not only possible to obtain a polymer with a high degree of polymerization, but also to obtain a polymer with a high degree of polymerization. The present invention was completed after discovering that the variation could be reduced and conducting further research.

In the present invention, p-phenylenediamine di, terephthalic acid A chloride k, and N-substituted carbonamide type solvent are polymerized using a solvent system in which calcium chloride is added, and heating is performed at 250 to 500'C for 5 hours or more. This is a method for producing polyvalent phenylene terephthalamide, which is characterized by using treated calcium chloride.

Calcium dichloride used in the present invention has a temperature of 250°C.
It must be heat-treated at a temperature of at least 500°C. If the heat treatment temperature is below 250'C, a polymer with a sufficiently high degree of polymerization cannot be obtained. At temperatures above 500° C., calcium chloride undergoes deterioration due to thermal decomposition, etc., so the degree of polymerization of the obtained polymer varies and is not suitable. From the heat treatment speed and practical standpoint, the heat treatment temperature is 300°C to 400°C.
'C is preferred. Further, the heat treatment time varies somewhat depending on the combination with the heat treatment temperature, but if it is less than 5 hours, a polymer with a high degree of polymerization cannot be obtained, so it is necessary to heat the polymer for at least 5 hours or more. If the process takes more than 5 hours,
It is possible to obtain a polymer with a high degree of polymerization and little variation in the degree of polymerization, and depending on the case, it is also possible to perform the treatment for several tens of hours or more. Preferably, the time period is selected within the range of 10 to 40 hours.

By polymerizing using calcium chloride heat-treated under such specific conditions, a polymer with a high degree of polymerization can be stably obtained. Although the reason is not clear, it is assumed that it is not simply due to the water removal effect contained in calcium chloride.

In other words, in conventional techniques, calcium chloride as a raw material usually contains water that inhibits polymerization, so to remove this water, calcium chloride is vacuum-dried at a temperature of about 200°C, or calcium chloride is dissolved in a solvent. After that, dehydration is carried out using an adsorption dehydrating agent such as molecular sheep.

In the heat treatment of the present invention, dehydration also occurs at the same time, especially at the initial stage, and as a result, calcium chloride with a low moisture content is obtained. However, when comparing calcium chloride heat-treated by the method of the present invention and calcium chloride obtained by a conventional dehydration method, it is found that the moisture content measured after dissolving in a solvent is comparable. First, by using calcium chloride treated by the method of the present invention, a polymer with a high degree of polymerization can be stably obtained. Therefore, the effect of the present invention is not due to dehydration of calcium chloride, but is due to the presence of water in the raw material, although it is not certain. It is presumed that this is due to the influence of impurities contained in K.

In the present invention, calcium chloride is added to K before heat treatment.
It may be preheated to around 200°C, or drying and heat treatment may be performed at the same time. Specifically, the heat treatment may be carried out by commonly used devices and means such as a hot air dryer, a hot air circulation type dryer, a ventilation batch type dryer, a hot air circulation type conveyor dryer, and the like. Although air is usually used as the heating medium, it is preferable to use an inert gas such as nitrogen or argon.

Calcium chloride after heat treatment is usually cooled to 80'C when it is charged into an N-substituted carbonamide type solvent, but it should be cooled in an inert gas atmosphere such as fluorine gas to suppress moisture absorption during cooling. is desirable.

Calcium chloride used in the heat treatment is not particularly limited in the present invention, and may be a hydrated salt in some cases, but preferably anhydrous calcium chloride. Further, although the form of calcium chloride is not particularly limited in the present invention, using a finely powdered one can shorten the heat treatment time, and it can be formed into a fine powder without solidifying during the heat treatment. It has good dispersibility when dissolved in N-substituted carbonamide type solvents,
This has the advantage of shortening adjustment time and improving productivity.

In the present invention, the concentration of calcium chloride in the N-substituted carbonamide type solvent is usually 0.30 to 0.90 mol/l, preferably 0.45 to 0.75 mol/l. In addition, the monomer concentration is 0.30 to 0.50
Usually carried out in mol/l, practically 0.4 to 0.45
Mol/l is preferred. Further, the concentration of calcium chloride is usually about 1.5 to 2.0 times the monomer concentration. By carrying out the polymerization within this range, a highly polymerized polymer can be obtained in a short time with good dispersibility during stirring and good fluidity during the reaction of paraphenylenediamine and terephthalic acid dichloride. The method of dissolving calcium chloride with the N-substituted carbonamide solvent in the present invention is not particularly limited, and calcium chloride may be added to the N-substituted carbonamide solvent, or vice versa. .

The N-substituted carbonamide type solvent used in the present invention refers to a single or mixed solvent selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, and N-acetylpyrrolidine, especially chlorinated N-methyl-2-pyrrolidone is superior because it has fewer side reactions with calcium.

In the present invention, the full effect is exhibited even more at high monomer concentrations. High monomer concentration means 0.
．． It refers to 40 to 0.50 mol/l, and in conventional methods, high polymerization was only possible up to 0.30 to 0.35 mol/l. By employing the method of the present invention, for example, polymerization can be carried out at a monomer concentration of 0.45 mol/l with a calcium chloride concentration of 0.70 mol/l, and a polymer with a high degree of gravity can be stably obtained.

Also, the form of terephthalic acid tetrachloride to be subjected to polymerization may be arbitrarily selected from powder form, molten form, etc., but for example, if it is added in molten form, it can be added quickly and the terephthalate tetrachloride during polymerization can be added quickly. 0 The polymerization temperature is usually carried out within the range of -10 to 70°C, which is preferable because it can increase the diffusion rate of Gium chloride.
If it is too high, the decomposition reaction of the solvent and monomer will be intense, which is undesirable. Further, the allowable content of impurities in the solvent is preferably 500 PPM of water, and in order to obtain a high degree of polymerization, the water content is more preferably 200 PPM or less. Although it is preferable not to include a container that acts as a polymerization terminator, it is also possible to use a monofunctional metal or the like as a terminator for the purpose of adjusting the degree of polymerization.

In order to obtain high molecular weight poly(per)phenylene terephthalamide by the method of the present invention, the molar ratio of para-phenylene diamine and terephthalic acid dichloride must be 'fl'.
It is preferable to make it equal to . However, for the purpose of adjusting the degree of polymerization, one may freely deviate this ratio by a little more than 1.

In polymerizing bolivar phenylene terentalamide by the method of the present invention, it is preferable to apply a large shearing force to the polymerization system in order to obtain a polymer with a high degree of polymerization.

The polymerization of the present invention can be carried out either batchwise or continuously. When carrying out batchwise, it can be carried out using, for example, a polymerization tank equipped with stirring blades, a kneader, or the like. To do this continuously, after dissolving calcium chloride in an N-substituted carbonamide type solvent, adding and dissolving or mixing paraphenylene diamine, or mixing, continuously add terephthalic acid dichloride, e.g. This is carried out by mixing in a self-cleaning continuous kneader or the like, and for example, by adding 90 mol ter or less of terephthalic acid dichloride of para-phenylene diamine and then using a para-phenylene diamine solution, this is 'tN-substituted carbonamide type. It is also possible to mix a solution of calcium chloride in a solvent, or to mix it and then continuously mix it with the remaining terephthalic acid dichloride. , methanol, chloroform, etc., and then drying to isolate the polymer, which is then redissolved in sulfuric acid or the N-substituted carbonamide type solvent described above. The resulting polymer can be diluted to form a dope with a suitable viscosity and then formed into fibers, films, fibrids, etc. by wet, dry, or air-gap wet spinning methods.

(Effects of the Invention) Due to its excellent heat resistance, phenylene terephthalamide is useful as fibers, films, 7-iprids, etc., and these molded products are widely used in both industrial and clothing applications. For example, it is used in fields such as reinforcing materials for tires, belts, etc., reinforcing materials for resins, and as heat-resistant clothing, heat-resistant films, heat-resistant paper, etc., which have a melting point (or decomposition point) of 500° C. or higher. In this way, the characteristics of polypara-7-ethylene terephthalamide, such as high strength, high modulus, heat resistance, and flame retardancy, have been developed and it has been utilized in various fields. According to the method of the present invention, it is possible to produce a polymer having a high degree of polymerization for obtaining such useful molded articles, and a polymer having stable quality with little variation in the degree of polymerization.

(Example) Next, the present invention will be specifically explained by using examples. In addition,
The logarithmic viscosity ηinh, which is a guideline for the degree of polymerization, is es, s q
From the relative viscosity dar measured at 35°C using an Ostwald viscometer using a conventional method for a solution of polymer dissolved in sulfuric acid at a concentration of 0.2 f7100 m, Wi
It is calculated as nh = tnWr/c. Further, unless otherwise specified, the concentration is expressed as % by weight.

Example 1 Micronized anhydrous calcium chloride 220ff was placed in a dryer with hot air circulation and capable of slight vibration, and heated at a temperature of 330°C for 25 minutes.
After the heat treatment for an hour, it was quickly taken out of the dryer and cooled in a nitrogen blow chamber for 2 hours. Then calcium chloride 209.
80f was weighed into a closed test. Next, a water content of 42 PPM (2
) 2700 cc of N-methyl-2-pyrrolidone was added, the inside was filled with nitrogen gas, and the above-measured amount of calcium chloride was added within 60 seconds while stirring. After stirring for 90 minutes under nitrogen gas, it was confirmed that the calcium chloride was completely dissolved. When the moisture content of the solution was measured in this state, it was 106 PPM.

Add phenylenediamine 116.60f to this solution and dissolve for another 90 minutes.It was confirmed that phenylenediamine was completely dissolved.Ride 219.2
Although the solution solidified 180 seconds after adding Of, stirring was continued, and stirring was stopped after 10 minutes to obtain a polymer.

The polymer obtained in this way consists of powdery polymer cL,
It was washed with water several times and dried. As a result, the logarithmic viscosity η
A highly polymerized polymer having a roar nh of 9.73 was obtained.

Examples 2 to 4 Calcium chloride heat treatment time: 15 hours, 20 hours, 3
The experiment was conducted under the same conditions as in Example 1 except that the time was 0 hours.

The results are shown in Table 1.

Table 1 Examples 5 to 8 Except for the heat treatment temperature of calcium chloride being 350°C,
It was carried out in the same manner as in Example 1.

The results are shown in Table 2.

Table 2 Comparative Examples 1 to 8 Comparative examples 1 to 8 were carried out under the same conditions as in Example 1, except that calcium chloride was dried at 200°C and 550°C for 15 to 30 hours.

The results are shown in Table 3.

The moisture content of the polymerization system is similar to that of the method of the present invention, but η1
NH is low.

Margin below Table 3 Examples 11-34 Calcium chloride heat treatment 200°C, 240°C, 26
0℃, 300℃, 350℃, 400℃, 450℃, 51
The treatment time was 15 hours and 25 hours, respectively.
Polymerization was carried out in 4 batches under the same conditions as in Example 1 for 40 hours.

The results are shown in Table 144.

Calcium chloride When dried at 250° C. or lower, the intrinsic viscosity does not rise above 6, and the variation is large. By heat-treating calcium chloride at a temperature of 250°C or higher, an intrinsic viscosity of 6 or higher can be easily achieved.

In short-time treatment at 500° C. or higher, polymerization with an intrinsic viscosity of 6 or higher is possible, but the variation between repetitions is large, and when the treatment time reaches 40 hours, the intrinsic viscosity becomes 6 or lower. Furthermore, as is clear from Table 4, it was demonstrated that the method of the present invention had little variation in the degree of polymerization and that a polymer with stable quality could be obtained.

Claims (1)

[Scope of Claims] 1. Chlorinated chloride heat-treated at 250 to 500°C for 5 hours or more when polymerizing p-phenylenediamine and terephthalic acid dichloride in a solvent system in which calcium chloride is added to an N-substituted carbonamide type solvent. Method 2 for producing polyparaphenylene terephthalamide, characterized in that calcium is used, and the method according to claim 1, characterized in that the heat treatment temperature of calcium chloride is 300 to 400°C.