JPS6214569B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses N-methylpyrrolidone or N.N-
Economically and technically improved, industrially useful, highly polymerized poly-p-phenylene terephthalamide (hereinafter referred to as , sometimes abbreviated as PPTA). So-called wholly aromatic polyamides such as PPTA are useful as fibers, films, fibres, resins, etc. due to their excellent thermal and mechanical properties, and are obtained by low-temperature solution polymerization in amide-based polar solvents. This is well known. (For example, special public relations
No. 14399. ) Also, in this method, high polymerization degree
Solvent systems that give PPTA include hexamethylphosphoramide alone or a mixture of hexamethylphosphoramide and other amide polar solvents such as N-methylpyrrolidone (such as U.S. Pat. No. 3,869,429), and N-methylphosphoramide. Two suitable examples are systems in which inorganic salts such as calcium chloride and lithium chloride are added to N-dimethylacetamide, N-methylpyrrolidone, etc. (Vysokomol. Soyed. A12, 2185, 1970, etc.), which have been widely used since It was known. However, it has become clear that the use of hexamethylphosphoramide is not very desirable in terms of occupational hygiene. (Chem.and Eng.News,
(Sept. 23, 1975) Therefore, the latter inorganic salt addition system has been reviewed, and the technology for the calcium chloride addition system has recently been published. (JP-A-51-109099, JP-A-52-71593) The present inventors have discovered that calcium chloride-added PPTA
As a result of studying solution polymerization using a unique polymerization method that involves crushing and continuing to apply shear force to polymerization reaction intermediates produced during polymerization even after solidification, the following results were discovered. I found out. (1) Even in a solvent system in which calcium chloride is added to N・N-dimethylacetamide, PPTA with a high degree of polymerization is comparable to PPTA obtained in a solvent system in which calcium chloride is added to N-methylpyrrolidone. This is a result that contradicts the content of JP-A-51-109099, but this may be a reflection of the difference in the polymerization method, which mainly involves stirring and mixing. (2) In a system in which calcium chloride is added to N-methylpyrrolidone, the concentration of calcium chloride claimed in JP-A-52-71593 is such that when polymerization is carried out at an industrially useful high polymer concentration, It is often seen that the polymer dissolving power of the solvent system is insufficient and PPTA precipitates during polymerization, resulting in PPTA with a low degree of polymerization being obtained.The greater the shear force applied to the polymerization reaction intermediate, the more The difference in the degree of polymerization of PPTA when PPTA precipitation occurs and when it does not occur is expanded, and the calcium chloride concentration and polymer concentration should be correlated, and JP-A-51-109099
In the example disclosed in the issue, in addition to being economically disadvantageous if the concentration of calcium chloride is higher than necessary, the solvent system gels, probably because calcium chloride forms a special adduct with N-methylpyrrolidone. This is frequently observed, and this causes a situation in which the polymerization of PPTA is not carried out smoothly, and the polymer concentration (expressed as a weight percentage of PPTA formed with respect to N-methylpyrrolidone) is approximately 9.5. %, the polymerization product exhibits viscosity and is difficult to transport and handle, and there remains a problem with the corrosivity of the polymerization equipment. Therefore, the present inventors found that there remained a major problem in industrially manufacturing PPTA using the technology generally disclosed in these two applications, and While investigating suitable technology for
By carrying out the polymerization of PPTA at very limited and selected ranges of specific polymer concentrations and calcium chloride concentrations as generally and generally indicated in US Pat. It was discovered that technical problems such as low polymerization degree due to precipitation and gelation of solvents, difficulty in handling polymerized products, and corrosivity could be overcome, and that the process could be carried out economically. The present invention was completed by overlapping the above. That is, the present invention provides a method for preparing calcium chloride in a mixture consisting essentially of at least one of N-methylpyrrolidone and N.N-dimethylacetamide and calcium chloride.
In substantially reacting p-phenylene diamine and terephthalic acid dichloride to polymerize poly-p-phenylene terephthalamide, the poly- Let the weight percentage of p-phenylene terephthalamide (hereinafter sometimes simply referred to as polymer concentration) be Xp, and the weight percentage of calcium chloride to be mixed with respect to the total amount of N-methylpyrrolidone and N・N-dimethylacetamide (hereinafter , sometimes simply referred to as calcium chloride concentration) is defined as Xc, within the range that simultaneously satisfies the following four conditions ^: Xc>10 _Xc ≧Xp−3.2 Xc≦0.27 The method is characterized in that the polymerization reaction intermediate is pulverized at the same time as the polymerization system is solidifying or after solidification, and then a shearing force is applied to the pulverized polymerization reaction intermediate to complete the polymerization reaction. poly-p-
This is a method for producing phenylene terephthalamide. The method according to the invention can be carried out in various ways. For example, N-methylpyrrolidone and/or N.N-dimethylacetamide can be mixed with the required amount of calcium chloride, followed by addition of p-phenylenediamine and, with vigorous stirring, terephthalic acid dichloride. Alternatively, the components of the reaction system can be introduced in a different order, for example, first with N-methylpyrrolidone and/or N.N.
- Dimethylacetamide can be co-added with p-phenylenediamine by subsequent addition of calcium chloride. Or, for example, N
- simultaneous introduction of the monomers into the reaction medium by adding a powder mixture of p-phenylenediamine and terephthalic acid dichloride in the required mixing ratio for the methylpyrrolidone and/or N·N-dimethylacetamide-calcium chloride system; I can do it. However, when the amount of calcium chloride added to N-methylpyrrolidone and/or N.N-dimethylacetamide exceeds the saturation solubility of this mixture system, N-methylpyrrolidone or N.N.
- A special adduct is formed between dimethylacetamide and calcium chloride, and the mixture system becomes highly viscous (gelled) due to the formation of this adduct. Adding a powder mixture of p-phenylenediamine and terephthalic acid dichloride to the N-methylpyrrolidone and/or N·N-dimethylacetamide-calcium chloride system is undesirable in providing the necessary sufficient mixing effect to the polymerization system. The method is only suitable if the N-methylpyrrolidone and/or N.N-dimethylacetamide-calcium chloride system causes gelation. In the case of the other two methods, even if the reaction medium system temporarily gels, the concentration of the polymer of the present invention cannot be maintained.
As long as Xp and calcium chloride concentration Xc are maintained, p-
Since the gel disappears by the addition of phenylenediamine, a sufficient mixing effect can be imparted to the polymerization system at the start of polymerization, that is, at the time of introducing terephthalic acid dichloride. The materials involved in this reaction must contain a minimum amount of impurities. In particular, the presence of more than about 0.05% by weight of water, calculated on the total reaction mixture, results in only a low degree of polymerization of the polymer. Therefore, the two monomers as well as N-methylpyrrolidone, N.N-dimethylacetamide and calcium chloride should be practically water-free. The calcium chloride can be rendered water-free by drying the powder, for example at a temperature of 200° C. or higher, under vacuum or under normal pressure. In addition to accelerating the drying process, powdered calcium chloride has the advantage that it can be dispersed more rapidly and effectively in N-methylpyrrolidone and/or N.N-dimethylacetamide. In the present invention, calcium chloride concentration Xc (N
- The amount of calcium chloride to be mixed with respect to the total amount of methylpyrrolidone and N.N-dimethylacetamide, expressed as a weight percentage. same as below. )teeth
At a concentration exceeding 10% by weight and Xc≧Xp−3.2, Xc
It is necessary to satisfy ≦0.27X ² _p −5.13Xp+34.30. The reason for this limitation is that especially when the polymer concentration (Xp) is 10% by weight or less, the PPTA-containing polymer produced by the polymerization reaction is obtained as a sticky or wet gel-like substance, and therefore the polymerization In addition to being difficult to take out from the equipment and handle for post-processing, there are disadvantages such as rapid corrosion of areas that come into contact with polymers containing hydrogen chloride produced during polymerization reactions, such as polymerization equipment, making it difficult to carry out industrial production. It is not suitable for. On the other hand, if polymerization is carried out at the calcium chloride concentration and polymer concentration of the present invention, a dry gel-like material containing PPTA with a high degree of polymerization can be obtained, which is easy to handle and prevents corrosion of the polymerization equipment. The extent is surprisingly small. In carrying out the present invention, high polymerization degree
The obtainable limit Xp of PPTA is 16% by weight.
In addition, the polymerization reaction in the present invention is almost 100%
Since the calculation is performed based on the yield, it is easy to calculate the amount of monomer charged for the desired Xp. The lower limit of calcium chloride concentration Xc is when Xc>10
The reason why Xc is limited to Xp-3.2 is that if Xc is smaller than this, PPTA will precipitate during the polymerization reaction and only PPTA with an extremely low degree of polymerization will be obtained. On the other hand, the upper limit of calcium chloride concentration Xc is
^0.27 _{_} , N-methylpyrrolidone or N-N-dimethylacetamide in a state where calcium chloride and p-phenylenediamine are added and dispersed or dissolved in N-methylpyrrolidone or N-N-dimethylacetamide.
- A special adduct of dimethylacetamide and calcium chloride is frequently formed, resulting in gelation and high viscosity, which is why PPTA with a high degree of polymerization
This is because it is often difficult to provide a sufficient mixing effect necessary to obtain this to the polymerization system at the initial stage of polymerization. This adduct is chlorinated with a saturation solubility in the amide solvent (approximately 6 to 8% by weight for N-methylpyrrolidone and approximately 3 to 5% by weight for N.N.-dimethylacetamide at room temperature). It may be formed when calcium is added, and p-phenylenediamine has the property of interfering with the formation of adducts.
It was determined that the amount of p-phenylenediamine added is related to whether or not adduct formation occurs.As a result of detailed investigation, it was found that when Xc≦0.27X ² _p -5.13Xp + 34.30, addition It was found that gelation of the polymerization system due to the formation of substances did not occur. However, the production of adducts is slightly related to temperature in addition to Xc and _Xc ≦0.27X ^2p
−5.13Xp+33.80 is more preferable. Also, surprisingly, within the scope of the present invention, that is, Xc≦0.27X ² _p −
PPTA polymerized at a calcium chloride concentration of 5.13Xp+34.30 was found to have the advantage of being extremely superior in spinnability compared to PPTA polymerized at a calcium chloride concentration outside the range of the present invention. It should be noted that the scope of the present invention is illustrated in FIG. 1 in order to make it easier to understand. This is the shaded area in FIG. p-phenylenediamine and terephthalic acid dichloride are used in equimolar amounts or in slight excess of either of them compared to the other. Polymerization degree modifiers and other conventional additives can also be used. In the method of the present invention, N-methylpyrrolidone, N.N-dimethylacetamide or a mixture thereof in any proportion is used as the solvent.
The superiority or inferiority among these should be determined primarily by factors other than the polymerization process technology, such as price, difficulty in recovery, and stability. Note that different solvents such as other amide solvents, chloroform, acetic acid, γ-butyrolactone, n-hexane, etc. can be present in the reaction system in an amount of about 10% or less. Substances known in particular as acceptors for use in low-temperature solution polymerizations in solvents for the reaction mixtures according to the invention, such as calcium oxide,
Pyridine, N-methylmorpholine, triethylamine, particularly preferably N.N-dimethylaniline, etc. can be added and used. In the practice of the present invention, it is particularly necessary to mix the reaction mixture vigorously so that the p-phenylenediamine and terephthalic acid dichloride are sufficiently mixed with each other to react. This is because if the mixing is insufficient, PPTA with the desired high degree of polymerization cannot be obtained. The mixture is
It is preferable to carry out the stirring from the beginning of the polymerization reaction until the PPTA reaches its final degree of polymerization. In addition to vigorous stirring at the beginning of the polymerization reaction, even after the polymerization reaction system has solidified, pulverization and special shearing force should be applied. is desirable. More preferably, the shear force applied to the polymerization reaction intermediate is at a shear rate of 100 sec ^-1 or more or a stirring blade tip speed of 50 cm/sec or more. As a specific example of the polymerization apparatus, a general vertical stirring tank, a so-called Waring blender, a double motion stirring tank, a planetary motion stirring tank, a Henschel mixer, etc. can be used, but it is preferable to use a general vertical stirring tank. type stirring tank, preferably a stirring tank capable of rotational movement and reciprocating motion as previously proposed by the present inventors (Japanese Patent Laid-open No. 108381/1983), and a variable rotation radius stirring tank (Utility Application No. 6382/1982). Used as the first stage polymerization equipment that imparts intense mixing action in the first half of polymerization, such as screw type mixer, batch type or continuous type kneader, pressure type kneader, co-kneader, vertical type kneader, Banbury mixer, internal mixer, Henschel. This is a two-stage combination method in which a mixer, a votator, a reciprocating rotary reactor, etc. are used as a second stage polymerization device to further stir the highly viscous or solidified material in the latter half of the polymerization, crush it, and apply shearing force. Another example of a preferred polymerization device is a method of performing polymerization continuously, such as a "jet impingement mixer" (such as U.S. Pat. No. 3,849,074), a continuous mixer with a high shear rate, etc. It is a combination of an extruder, a continuous kneader (preferably a so-called "full surface renewal type continuous twin-screw kneader" disclosed in US Pat. No. 3,195,868, etc.), and the like. The method of continuous polymerization is the most preferable in that it can absorb the phase change accompanying the polymerization reaction in the most rational manner while imparting mixing effects such as intense mixing, pulverization, and application of shear force to the polymerization reaction system. In carrying out the method, the method that the present inventors have already disclosed in JP-A-50-128793 and JP-A-51-142100, which is carried out via a prepolymer, is incorporated into the present invention. is also one of the preferred embodiments. The method of the invention is carried out at temperatures below 70°C. Immediately after the rapid coalescence of the reactants, a sudden rise in temperature can be observed followed by a gradual rise in temperature caused by the mechanical energy of the stirrer. Preferably, the process is carried out such that the temperature of the reaction mixture is within the range of 0 to 60°C. This is accomplished by cooling before, during, and/or after the reaction. Temperatures below 0°C can also be used. The actual polymerization reaction proceeds quickly and is usually completed within 30 minutes. The monomers should be added together as quickly as possible, for example within 10 to 20 seconds, and then mixing is continued until the degree of polymerization of the PPTA reaches its final value. Stirring can be extended if necessary to break down the reaction product, which forms into a dried gel-like material, to a particle size suitable for coagulation. Poly-p-phenylene terephthalamide must subsequently be separated from the reaction mixture.
This can be done by first intimately mixing the reaction mixture with water or an aqueous alkali, for example in a Waring mixer. Poly-p-phenylene terephthalamide is filtered or centrifuged from the resulting suspension, purified with water, and dried. N-methylpyrrolidone and/or N·N-dimethylacetamide, calcium chloride, water and
N-methylpyrrolidone or/and N·N-dimethylacetamide and calcium chloride can be recovered from the filtrate consisting of hydrochloric acid formed during the reaction. The polymer produced in this way is formed into fibers, films, fibrils, etc. from a solution dissolved in concentrated sulfuric acid or the like by a wet method, a dry method, a space discharge followed by a wet method, or the like. These molded products are widely used for both clothing and industrial materials, such as heat-resistant clothing, heat-resistant hoses, heat-resistant films, heat-resistant paper, heat-resistant adhesives, flame-resistant curtains, flame-resistant woven fabrics, and flame-resistant carpets. Its characteristics are fully demonstrated in the fields of rubber reinforcing materials and resin reinforcing materials for , bag filters, ropes, tires, belts, airbags, etc. The invention is further illustrated in the following examples.
Unless otherwise specified, calcium chloride and poly-p
- Phenylene terephthalamide All weight percentages mentioned in the examples are based on the total amount of N-methylpyrrolidone and N.N-dimethylacetamide. Further, the logarithmic viscosity ηinh of poly-p-phenylene terephthalamide as a measure of the degree of polymerization is defined as follows. ηinh=lnηrel/0.5 where ηrel is the polymer solution (96% by weight in 100ml of sulfuric acid)
0.5g poly-p-phenylene terephthalamide)
It is the ratio of the efflux times of the pure solvent and the pure solvent as measured with a capillary viscometer at 25°C. Reference Example 1 and Comparative Examples 1 to 4 Polymer concentrations (Xp) and calcium chloride concentrations ( Xc), first 5 kg of N-methylpyrrolidone purified by distillation was added, then p-phenylenediamine, and then anhydrous calcium chloride were added and dissolved and dispersed. (For example, in Reference Example 1, 227 g of p-phenylene diamine and 500 g of calcium chloride are used.) Next, after cooling to 10°C, powdered terephthalic acid dichloride in an equimolar amount to p-phenylene diamine was quickly added and vigorously added. The mixture was stirred to initiate polymerization. Terephthalic acid dichloride quickly dissolved and reacted, and within 2 to 3 minutes, the polymerization reaction system rapidly became viscous and eventually became difficult to stir. Six minutes after the start of polymerization, the polymerization reaction product was taken out and transferred to a Henschel mixer made of stainless steel (SUS304).
High-speed processing at 8000 rpm was performed for 10 minutes to perform pulverization and application of shear force. The diameter of the stirring blade of the Henschel mixer used was approximately 30 cm at the tip, so
In that case, shearing force was applied at a stirring blade tip speed of approximately 12,600 cm/sec. The resulting polymerization mixture containing PPTA was transferred to a glass container, poured with about 20 g of water, washed with water, and filtered.
This operation was repeated five more times. The obtained polymer was dried and the logarithmic viscosity ηinh was measured. On the other hand, the filtrate is N-
The concentration of methylpyrrolidone and the concentration of metal (Fe, Ni) ions were measured, and their ratio (weight ratio of metal ions to N-methylpyrrolidone) was calculated and used as a guideline for the degree of corrosion of the polymerization apparatus. Since this ratio for each washing stage was constant within the range of measurement error for the same polymerization batch, it is shown in Table 1 only for the first washing filtrate. Table 1 summarizes these results. In addition, the first
Although not shown in the table, in Comparative Examples 1 to 4, it was more difficult to discharge from the Henschel mixer than in Reference Example 1. In other words, in the case of Reference Example 1, almost all of the polymerization reactants could be discharged by simply opening the discharge valve and slightly rotating the stirring blade, but in the case of Comparative Example 1, which is not within the scope of the present invention, this was not the case. It was difficult to discharge by simple operation alone, and the particles often remained near the center of the stirring blade, with a particularly large amount of Comparative Examples 2 and 4 remaining. As can be seen from Table 1 and this phenomenon, outside the scope of the present invention, if Xc is appropriately selected, PPTA with a degree of polymerization comparable to that of Reference Example 1 can be obtained; ) is used in a relatively large amount, handling of the polymerization reactants is troublesome, and the polymerization equipment is prone to corrosion, so it is clear that this method has considerable disadvantages in industrial implementation.

[Table] Example 1 A cylindrical separable flask with a lid made of stainless steel and a body made of glass was prepared.
A stirring blade rotatable at 300 rpm was set up. Next, the separable flask was dried by heating from the outside while flowing dry nitrogen into the interior of the separable flask. Put 500g of distilled N-methylpyrrolidone into a separable flask, and add 60g of powdered reagent grade calcium chloride (Xc
= 12%) added and dissolved. Add and dissolve 29.5g of p-phenylenediamine while some of the calcium chloride is suspended, then adjust the temperature to -5℃, and then melt at 95~110℃ and 55.4g of terephthalic acid dichloride. was added and stirred at approximately 300 rpm. The polymerization reaction proceeded in a transparent state throughout, and after the polymerization reaction product began to solidify, it was stirred at 200 rpm for 10 minutes. The produced dry crumb-like polymerization reaction product containing Xp = 13% PPTA was first washed with a 5% quicklime aqueous solution and then with water several times, dried to obtain a polymer, and the logarithmic viscosity ηinh was measured. . ηinh=4.10. (Example 1 is indicated by G in FIG. 1.) Example 2 and Comparative Examples 5 to 7 Polymerization was carried out in the same manner as in Example 6, and the results shown in Table 2 were obtained.

[Table] As is clear from Table 2, those polymerized outside the range of the method of the present invention, that is, Xc<Xp-3.2 (Comparative Example 5
In cases 7) to 7), turbidity of the polymerization reaction solution occurred shortly after the start of polymerization, probably due to precipitation of the polymer, and the degree of polymerization of the obtained PPTA was lower than that obtained when the polymerization was carried out within the scope of the method of the present invention. PPTA
The degree of polymerization is significantly lower than that of Examples 3 to 5 and Comparative Examples 8 to 11 Polymerization was started in the same manner as in Example 1 using the separable flask used in Example 1. however,
4 minutes after the start of polymerization, the separable flask was disassembled in a dry atmosphere and the contents were taken out, and the internal volume was approximately 2.
The mixture was transferred to a small test kneader, covered with a lid, and processed in the kneader for about 20 minutes while running cooling water through the jacket. At this time, a shear rate of 185 sec ^-1 was calculated to be applied, and the lid was useful in order to do this effectively. Post-treatment of the polymerization reaction product and measurement of logarithmic viscosity were also carried out in accordance with Example 1. The dissolution and dispersion of calcium chloride in N-methylpyrrolidone were all carried out at room temperature for about 2 hours, and the presence or absence of gelation of the reaction solution was observed during addition of p-phenylenediamine and after dissolution of p-phenylenediamine. I did this. These results are shown in Table 3. From Table 3, the range of the method of the present invention, that is, Xc≦
PPTA with a high degree of polymerization is obtained in Examples 3 to 5 that satisfy 0.27X ² _p -5.13 Gelation (increase in viscosity), which is thought to be due to the formation of adducts, occurs at the start of polymerization, that is, when terephthalic acid dichloride is added.
As a result, dissolution, dispersion, and mixing of terephthalic acid dichloride cannot be performed smoothly, resulting in a low degree of polymerization.
It turns out that you can only get PPTA.

【table】 [Brief explanation of the drawing]

FIG. 1 illustrates the operational range of the present invention, namely calcium chloride concentration (Xc) and PPTA concentration (Xp). G, H, L, M, and N are illustrations of Examples 1, 2, 3, 4, and 5 belonging to the scope of the present invention;
C, ..., L are illustrations of Comparative Examples 1, 2, 3, ..., 11 that do not fall within the scope of the present invention.

Claims (1)

[Claims] 1. Substantially N-methylpyrrolidone and N.N-
In the step of polymerizing poly-p-phenylene terephthalamide by reacting substantially p-phenylenediamine and terephthalic acid dichloride in a mixture comprising at least one dimethylacetamide and calcium chloride, N-methylpyrrolidone and The weight percentage of poly-p-phenylene terephthalamide produced relative to the total amount of N.N-dimethylacetamide is Xp, and the calcium chloride to be mixed relative to the total amount of N-methylpyrrolidone and N.N-dimethylacetamide is Weight percentage of Xc
When the polymerization is carried out within a _range that simultaneously satisfies the following ^four conditions: Xc>10 Xc≧Xp−3.2 Xc≦0.27 A poly-p characterized in that the polymerization reaction intermediate is pulverized at the same time or after solidification, and then a shearing force is applied to the pulverized polymerization reaction intermediate to complete the polymerization reaction.
- A method for producing phenylene terephthalamide. 2. The method for producing poly-p-phenylene terephthalamide according to claim 1, characterized in that Xc≧Xp−2.7. 3 Xc≦0.27X ² −5.13Xp+33.80.
Process for producing phenylene terephthalamide.