SU833163A3 - Method of preparing polyamides - Google Patents

Abstract

Continuous prepn. of a polyamide of formula (I): (in which 50-100% of the R groups are p-phenylene groups and 0-50 wt.% are n-butylene groups), comprises reacting molten terephthaloyl chloride (TPC) and opt. adipoyl chloride with a soln. of p-phenylenediamine and/or 4,4'-diaminoadipanilide and opt. of a prepolymer of the acid chloride and diamine, in a mixt. of N-methylpyrrolidone-2-(NMP) and CaCl2. The polymer having an inherent viscosity >=3, measured on a soln. in 100% sulphuric acid at 25 degrees C at a concn. of 0.5g polymer in 100 ml solvent. The reaction conditions are such that the acid chloride and the diamine are in stoichiometric amts. The soln. of diamine is homogeneous. The mole ratio between the CaCl2 and the no. of units (I) is >=1 pref. >=1.15 and the relative amts. of reactants and solvents is such that at the end of the reaction the compsn. contains >=5 wt.% polyamide wrt NMP. Compared to prior art, the process is non-toxic. NMP is also more stable to hydrolysis and thermolysis than hexamethylphosphotriamide, resulting in reduced losses during recovery. Also only small amts. of CaCl2 are used.

Description

(54) METHOD FOR OBTAINING POLYAMIDES

one .

The invention relates to a process for the continuous production of polyparaphenylene terephthalamide and its copolymers with improved viscosity. "

A known method for producing aromatic polyslides such as polyparaphenylene terephthalamide, acidic and with a viscosity greater than one, in sulfuric or hydrofluoric acid, different Q -amide amides and urea derivatives, namely dimethylacetamide (DMMA), 1Y-methylpyrrolidene-2 (NMP ); hexame- .tilphosphoriamide (HMPA) and tetramethyl aochevine (TMM). Salts such as lithium chloride or calcium can be eilt. added to amides and urea derivatives; polyparaphenylene terephthalamide is prepared. (PPD-T) in a mixture with. HMPT / NMP in a weight ratio of 1: 2. BUT, it is known that HMPA is a salvific globular substance, so that when it is used, great precautions are needed, which considerably complicate the process. This method 25 allows the preparation of other aromatic polymers in situ in a solvent that is used for the spinning compositions. For example, as in the case of poly-JQ parabenzamide, the preparation of which in TMM is completed in the presence of ZiCI, which occurs when the resulting HC I is neutralized with lithium carbonate flj.

But this method gives polymers with low viscosity. This refers to the preparation of polychlorophenylene terephthalamide in a mixture of DMAA with 1% ZiCI, but here we are talking about a much more soluble polymer than PPD-T.

There is also known a method for producing PPP-T with a viscosity of at least 2.5 (measured at 25 ° C in a solution of 0.5 weight PPD-T in 100 ml of 96% sulfuric acid) by reacting p-phenylenediamine and terephthalic acid chloride in a mixture NMP and calcium chloride in a ratio of 5% in relation to NMP, but preferably higher. And even beyond the solubility limit, to remain in suspension and even with a weight quantity at least equal to the weight quantity of PPD-T formed, if you wish to pselute increased values of the characteristic viscosity 2j.

However, such a method is costly, difficult for industrial use, especially in a continuous process. In particular, such a method that uses significant amounts of calcium chloride, which is hygroscopic, can lead to significant difficulties in industrial use when dehydrating the recovery, regeneration and processing of effluxites. - The purpose of the invention is to intensify the process, which is continuously implemented. The goal is achieved by the method of obtaining polyamides, with ornates in the reaction of p-phenylediamine and dicarboxylic acid chloride, taken stoichiometrically in a mixture of N-methylpyrrolidone and calcium chloride, and the solution is dissolved in a mixture of dihydroxycarboxylic acid. homogeneous and anhydrous and the molar ratio of calcium chloride used to the degree of condensation is 1-2.75, and the relative amount of reagents and solvent is such that at the end of the reaction The reaction solution contains 5 wt.% polyamide with respect to N-methyl pyrrolidine. The temperature of the diamine is between 0-50 ° C, and the dichlorohydrin is between 60-120 ° C, the preparation of polyparaphenylene terephthalamide / adipamide copolymer is carried out by reacting terephthalyl chloride and adipoyl in a solution of paraphenylenediamine, or by reacting terephthaloyl chloride in a solution of diamino-4, in a solution of diamino-4, a mixture of 4phenylenediamine, or a mixture of terephthaloyl in a solution of diamino-4, diamino-4, 4-diaphenylenediamine, or a mixture of terephthaloyl chloride in a solution of diamine-4, in a solution of diamino-4, 4-diaphenylenediamine; mixed with paraphenylenediamine, or to react the chlorides with a solution of a mixture of diamines. Chlorides can be injected simultaneously (in a mixture or separately), or sequentially. In either case, the preparation of a PPD-T homopolymer or copolymer can also be carried out by reacting one or more chlorides with a prepolymer prepared from chloride and diamine, taken from those mentioned above, in a mixture with a diamine. The diamine solution mixed with HMA + + CaClx; i should be homogeneous, i.e. it should not contain at the time of its use a suspension of simple or complex calcium chloride, which disrupts the regularity of the solution supply, i.e. the course and flexibility of the method and, consequently, the uniformity of the viscosity of the polymer obtained, thereby destroying all the advantages of the continuous method. For this, the weight concentration of calcium chloride in NMP should not exceed 6-8%. The solubility limits vary depending on the water content and the temperature of the diamine solution, the dissolution method (time and temperature), and the type of calcium chloride used (powder, flakes or crystals). A solution of diamine in a mixture of HMn + CaCl should not contain water. A portion of one or more chlorides may be added to it in order to obtain a solution of the diamine and the prepolymer. After cooling and storage for several days, protected from light, a continuous reaction is carried out. This solution with the remaining part of one or more chlorides, added to the stoichiometric ratio. The term dichloride is used to designate terephthaloyl chloride and for eroi mixture b b adipoyl chloride. Also, the term diamine is used for both paraphenylenediamine and for diamino-4,4-adipanilide or a mixture thereof, simple or combined with a prepolymer. In order to implement the method, the stoichiometry between the dichloride and the diamine must be well observed, which is necessary for obtaining a high viscosity. The injection of dichloride and diamine solution must be accurate and regular. And since a substantial part of the reaction between the dichloride and the diamine occurs extremely quickly, within a second, it is necessary to immediately carry out instantaneous or almost instantaneous mixing (which is an effective method of injection and mixing). The temperature of the acid dichloride should be sufficient so that it is in a liquid state and should not be too high. in order not to overheat the reaction mixture and not to cause its decomposition. Normal or lower temperatures are used for adipoyl chloride, and 85-120 seconds are preferred for terephthaloyl chloride. The two chlorides are mixed before injection and a temperature of 60-120 ° C is used for the diamine solution. The temperature of the diamine solution lying between can vary depending on the molar ratio of CaSD-3. Para-phenylenecarbonamide. It is also possible, if the technology permits, to operate with a temperature higher and even lower than 0 ° C until the diamine solution crystallizes. The molar ratio between calcium chloride and the number of units {degree of concentration) -NH-CO-R-CO should be equal to one for copolymers, but for pure PPD-T it should be equal to 1.15. Best results are obtained for the molar ratio lying between 1.25 and 2.76. The relative amount of reagents and solvents is chosen in such a way that at the end of the reaction the resulting composition contains 5 wt.% Polyamide with respect to the NMP. The preferred concentration is -6-10%. The initial injection temperature of the NMP / CaCl (i) solution diamine must be consistent with the solubility of the constituents before and after mixing the reagents and lower than the calcium chloride concentration. The initial micromixing of dichloro and the solution of diamine should be instantaneous or almost instantaneous. For this, it is convenient to use a highly efficient mixer fitted with an apparatus for very precise injection of reagents. For example, a device can be used with a rotor rotating at high speed in a fixed vessel, leaving a small gap for the passage of matter between the rotor and the stator in order to provide very effective and rapid mixing during the first seconds of the reaction. After this first piece of equipment, which does not need a large volume, to provide a residence time of about a second, the substance passes into the second part, in which its kneading continues, but more slowly, for example, in apparatuses having one or several screw mixers. In the manufacture of the copolymer, it is possible to provide an additional injection device for dichlorides located near two injection devices for other reagents and slightly lower in relation to them. Other apparatus can also be used, ensuring that they are sufficiently effective to provide a quasi-instantaneous initial mixing between the reagents. The continuous method allows the PPD-T to be obtained with very high accuracy or its copolymers derived from adipic acid with viscosity from 3 to 4 and reaching 6.5-7 or more measured in 100% H.2.S04 .. Viscosity is calculated by the expression. In t is the relative V I Q / where:, C is the weight concentration per volume, expressed in grams per 100 relative viscosity. Measured in solutions at 25 s in 100% sulfuric acid and at a concentration of 0.5 g of polymer in 100 ml of solvent. . The average weight of a molecule. M is determined by the method of light scattering under the following experimental conditions. Purification of the solution (concentrations, and 0.04-0., 20% by weight) and sulfuric acid, used as solvent, is 86% pure for the PROLABO NOPMAPUP analysis) and is carried out in a centrifuge at 25000 g for 4 hours The measurements are carried out at ordinary temperature on a FiCA 50 instrument equipped with a light source — a mercury lithium with an anti-fluorescent filter of 0.546 microns, mounted on a scattered beam (standard benzene double distillate, incident beam: unpolarized light of 0.546 microns). Measurements of the intensity of the scattered light are carried out at intervals of 7.5 or 15 to 30 or 150 °, the vertical and horizontal components are determined at 90 °. The processing of the measurements is carried out using the obtained uniform ZiMH diagram, by double extrapolating the concentrations and viewing angle to zero. The depolarization ratio is determined at zero concentrations and the correction factor CA8A factor NNES is calculated. The increment of the coefficient of magnitude of the system under study is that the polymer (96% sulfuric acid) is measured in the usual way on a differential refractometer (such as a Deba). Examples 1-19. For all these examples, NMP is used, containing at least 200 ppm w / w water and calcium chloride crystallized with two water molecules, dried under vacuum at C and containing 0.2% water. A rotor / styrator mixer with grooves is used, having protrusions in a capacity of 26 cm. The active element is a mixing turbine rotating at a speed of 5500 rpm. Experimentation was carried out with a flow rate of p-phenylenediamine solution of 1 l / min. Simultaneously with great accuracy and regularity, molten terephthaloyl chloride is injected on the one hand, maintained at, and on the other hand, a solution of p-pheniglendiamine in the MMP / CaCl mixture. in different proportions and at different temperatures. The substance exiting the mixer passes into a double screw apparatus with a nominal capacity of 5.4 liters, where it is additionally mixed. In tab. 1 indicates, for various examples, polymer concentration, expressed in wt.% Relative to NMP: PPD-T / NMP,%: CaCI content, j, expressed in wt.% Relative to NMP, CaCI-i / HMP,%; molar ratio CaCI / p-phenylene terephthalamide unit. See, the initial injection temperature of the diamine solution: T C and the resulting viscosity.

Note. 1- water content. in NMP 420 ppm; 2 - water content in NMP 1100 ppm.

The data in the table show that experiments carried out either by too low a molar ratio of Cm (examples 15 and 15 bis), or with a mixture of diamine / NMP / CaCI2. too saturated with calcium chloride, especially water, as well as diamine, leads to the formation of polymers with too much Mesh viscosity.

The polymer obtained in example 5 has a molecular weight of 5100Q and the polymer

Table 1

Obtained in Example 11, molecular weight 4760.0.

Examples 20-23, Repeat the example with the concentration of the polymer. with respect to NMP of 9.53 wt.% and with a molar ratio of 1.55 of a starting point) without using solutions of p-phenylenediamine

in NMP + CaCI

at other temperatures.

The results are shown in Table. 2

table 2

The results show that for the average polymer concentration and for

Examples 26 and 27 show that it is still possible to obtain a copolymer with a viscosity greater than 3 for the molar ratio of CaC 1 / middle unit of the copolymer equal to 1; 075, subject to the use of a low temperature of the diamine solution.

The polymer obtained in Example 24 has a molecular weight of 6900.

Example 28. In the same salt reactor, which is used in the preceding examples, a mixture of terephthalide and adipoyl chloride is injected at the same time in a molar ratio of 86:14 and p-phenylenediamine solution in an MMP-CaCId mixture at 23 ° C so that the weight content CaCl1 was 5.43% with respect to NMP and so that the molar ratio of CaC 1, / the average coT1O-lem unit was 1.29.

A scattering composition containing 7.631 copolymers with a viscosity of 3.72 is obtained.

Example 29. PPD-T, prepared under conditions analogous to Example 16, has the following viscosity:

the average value of the CaCl2 / zveco p-phenylene terephthalamide-amolar ratio of the obtained polymer is the higher, the lower the temperature.

Examples 24-27. Several solutions of diamine and a mixture of NMP + CaC 1 are prepared. The content of p-phenylenediamine and diamine-4,4-adipanilide is in the 63:37 weight ratio, but in varying amounts and the temperature and CaC content vary.

At the same time, each prepared solution and molten terephthaloyl chloride are injected at the same apparatus as in the previous examples.

The results are shown in Table. 3

.Table.Z

When measured at 100% H2.50d at 3.65

0 When measured in 96% SO at 25С3,02

 When measured in 96% HjSO at, 95

Squeeze out a hot solution containing by weight 18.5% of this polymer into frequent sulfuric acid (100%) through a filter with 250 holes of 60 microns in size. Before entering the coagulum bath, which was washed at a low temperature, the freshly applied filaments pass through the air layer. Then the thread is neutralized, washed and wound at a speed of 20 m / min. The thread has the following 5 properties (average of 10 measurements per one thread, sample length: 2.5%): Yarn number, dtex 1.50 Tear resistance, CN / Tex 181 0 Elongation,% 3.92

Initial modulus of elasticity5360

This example shows that it is possible even with a polymer with slightly increased viscosity prepared by

in accordance with the proposed method, to obtain fiber, with a very high quality

Examples 30-33. The procedure is performed as described in Example 1, but a homogeneous solution containing 8.28% by weight of CaCla is used. in NMP and 20 ppm of water, obtained by dehydration, by distillation at a pressure of 85 torr.

. Table 4 shows, for various examples, the polymer concentration, expressed in% by weight relative to NMP:: PPD-T / NMP,%; molar ratio CaC12. / p-phenylene terephthalamide unit,. the initial injection temperature of the diamine solution and the resulting viscosity.,

Table 4

It is less high than PPD-T viscosity.

 Examples 39-40. Within 14-30 minutes, 35.6 hours of chloride are added to the reactor, containing a solution consisting of 10861 parts of paraphenylenediamine in a mixture of NMP-CaC l, maintained at and containing 7.1% of CaC 12 and 150 ppm of water . The resulting prepolymer solution is maintained for 3 hours (Example 39 or 24 hours (Example 40).

Then, a solution simultaneously with molten terephthaloyl chloride at 98 s in a stoichiometric ratio is injected into a reactor similar to the reactor of Example 1, but with a volume of SS3

The examples show (with respect to example 18) that good results can be obtained with a high CaC / 2 content, provided that the diamine solution in the NMP + CaC l, j mixture is homogeneous, even for too high concentrations of the diamine.

Example 34. Operate similarly to the previous examples, but with a relative polymer concentration in NMP equal to 8.30 wt.%, With a molar ratio of Stm 1.85 and using a pre-dried solution with a water content of 150 ppm and CaC NMP 7.1 weight. Terephthaloyl chloride is used at 98, and paraphenylenediamine solution at 20 ,.

C a

The most significant viscosities for the copolymer are obtained.

Example 41. Reproduction of Example 39, but adding adipoyl chloride to the reactor containing a solution of paraphenylene diamine in a mixture of NMP + CaClg containing 500 ppm of water. In this case, a viscosity of 3.66 is obtained.

Examples 42-46. Prepared paraphenylenediamine solution in various NMP + CaCI / z mixtures. Then

one time, different amounts are added in different examples of chloride, adipoyl in order to form a prepolymer solution with adipine units.

This solution, along with a stoichiometric amount of molten terephthalyl chloride, is injected into the same reactor as in Example 39.

The data obtained are given in table. 7. Table

Claims (3)

1. The method of producing polyamides by the reaction of n-phenylenediamine and dichlorangide35 in a stoichiometric ratio, in a mixture of N-methylpyrrolidone and calcium chloride, characterized in that, in order to intensify the process carried out continuously, a homogeneous and anhydrous solution of diamine or prepolymer b is used. mixtures of N'-methylpyrrolidone and calcium chloride with a molar ratio of calcium chloride to the degree of polycondensation of polyamide equal to 1-2.75, and the starting materials are used in an amount providing a concentration of the obtained polyamide in N-methylpyrrolidone equal to 5 wt.%. 2. The method according to claim 1, characterized in that the temperature of the supplied dicarboxylic acid dichloride is 60-120 ° C. , 3. The method according to claim 1, characterized in that the temperature of the supplied diamine or prepolymer is 0-50 ° C.