JP2850317B2 - Method for producing aromatic polyamide dope - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an aromatic polyamide dope. [Prior art] Conventionally, as a method for producing an aromatic polyamide dope,
Production from aromatic diamines and aromatic diacid halides is most common, but production from aromatic dicarboxylic acids and aromatic diisocyanates is already known. [Problems to be Solved by the Invention] However, in the former method, complicated steps such as reprecipitation are required during neutralization for removing corrosive gas by-produced as a condensate during polymerization. In the latter case, the reaction between the diisocyanate and the dicarboxylic acid hardly occurs selectively, so that the molecular weight cannot be increased and the fiber or film cannot be processed. In addition, various catalysts have been provided for increasing the molecular weight, but they have not been found to have a sufficient effect,
Alternatively, even if the manifestation of the effect is seen, the catalyst is insoluble in the solvent, so that the dope is reprecipitated in a poor solvent, the catalyst is removed and dried,
A cumbersome process is necessary, such as having to redissolve and use. Encyclopedia of Polymer Science and Technolo
Although tertiary amines, potassium acetate, cobalt, manganese, and other heavy metal salts described in gy vol.11.517 are known, their effectiveness as polymerization catalysts is extremely small, and no satisfactory results have been obtained. Was. As catalysts for dicarboxylic acids and diisocyanates, metal alkoxides (USP 4,061,622), lactamates (USP 4,049,86)
6), mono- or dicalcali metal salts of dicarboxylic acids (JP-A-51-151615, 61-9421), cyclic phosphorous oxides (USP 4,156,065) and the like. If the effect is not seen or the effect can be achieved, the catalyst is insoluble in the solvent, so if the dope is processed directly into a fiber or film, the catalyst will remain in the product as foreign matter, and the fiber or Since a problem such as deterioration of the mechanical and electrical properties of the film occurs, a step of separating the polymer and the catalyst is always required. An object of the present invention is to easily generate a high molecular weight without generating highly corrosive hydrogen halide,
It is another object of the present invention to provide a method for stably producing an aromatic polyamide which can be processed into a film or a fibrous form of the obtained dope as it is. [Means for Solving the Problems] To achieve the above object, the present invention provides the following configuration: Or an aromatic dicarboxylic acid containing at least 60 mol% of a mixture thereof, wherein X is one or more selected from a halogen group, a nitro group, and a cyano group. L is an integer of 1 to 4. ) And an aromatic diisocyanate represented by the general formula OCN-R ₁ -NCO (where R ₁ is Wherein Y is at least one selected from a halogen group, a nitro group, a cyano group, an alkyl group having 1 to 3 carbon atoms, and an alkoxy group, and Z is -CH
_{2 -, - O -, -} S -, - SO 2 -, It is a kind selected from among. r is an integer of 0 or 1. m, n, and p are integers of 0 to 4, and q is an integer of 0 to 3. ) In an aprotic organic polar solvent in the presence of 1 to 300 mol% of tertiary amine (based on the number of moles of monomers charged). In the present invention, for at least 60 mol% of the aromatic dicarboxylic acid, it is necessary to use a monomer having one or more electron-withdrawing groups in the benzene nucleus. The electron-withdrawing group exerts an effect of significantly improving the reaction activity between the dicarboxylic acid and the diisocyanate in the presence of the tertiary amine, and at the same time, the aprotic organic solvent of the polyimide obtained by the polarity of the substituent. It is considered that the solubility in water is also improved, and the polymerization in a homogeneous system becomes possible, effectively working to increase the molecular weight. The dicarboxylic acid containing an electron-withdrawing group is 60
When the amount is less than mol%, the reaction activity is low, and the solubility of the polyamide in an aprotic organic polar solvent is low. However, only a polymer dope having poor storage stability or having extremely low storage stability can be obtained even if the molecular weight can be increased to some extent, and the object of the present invention cannot be achieved. The dicarboxylic acid having an electron-withdrawing group is 60
%, More preferably 70% by mole or more. With this composition, the reaction activity of dicarboxylic acid and diisocyanate and the solubility of the polymer can be further improved, and a stable polymer dope can be obtained. The dicarboxylic acid of less than 40 mol% is not particularly limited as long as it has a carboxyl group directly on the aromatic ring. Next, typical examples of the dicarboxylic acid and diisocyanate constituting the aromatic polyamide of the present invention will be described. As the dicarboxylic acid component, 2-chloroterephthalic acid, 2,3-
Dichloroterephthalic acid, 2,6-dichlorodephthalic acid,
2,3,5-trichloroterephthalic acid, 2-bromoterephthalic acid, 2,6-dibromoterephthalic acid, 2-fluoroterephthalic acid, 2-iodoterephthalic acid, 2-nitroterephthalic acid, 2,6-dinitroterephthalic acid 2-cyanoterephthalic acid, 2-chloroisophthalic acid, 2,6-dichloroisophthalic acid, 2-bromoisophthalic acid, 2,6-dibromoisophthalic acid, 2-fluoroisophthalic acid, 2-nitroisophthalic acid, 2-cyano Isophthalic acid and a mixture thereof; and the like, preferably, 2-chloroterephthalic acid, 2,3-dichloroterephthalic acid, 2,6-dichloroterephthalic acid, 2-bromoterephthalic acid, 2-nitroterephthalic acid, and 2-chloroterephthalic acid. Isophthalic acid and 2,6-dichloroisophthalic acid. The copolymerization component of the dicarboxylic acid is not particularly limited as long as it has a carboxyl group directly on the aromatic ring as long as it is 40 mol%, but, for example, terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, Phenylmethane-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, diphenylmethane-3 , 3'-
Dicarboxylic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenyl sulfone-3,3'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,4
-Dicarboxylic acid and the like, and terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid and mixtures thereof are preferable.The diisocyanate component is diphenylmethane- 4,4'-diisocyanate, 3,3'-dichlorodiphenylmethane-4,4-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylether-4 , 4'-diisocyanate, 3,3'-dichlorodiphenyl ether-4,4'-diisocyanate,
Diphenyl ether-3,4'-diisocyanate, diphenyl ether-3,3'-diisocyanate, toluylene-2,6-diisocyanate, toluylene-2,4-diisocyanate, phenylene-1,3-diisocyanate, phenylene-1, 4-diisocyanate, 2-chlorophenylene-1,3-diisocyanate, 2-chlorophenylene-1,4-diisocyanate, biphenyl-4,4 '
-Diisocyanate, diphenylsulfone-4,4 '
-Diisocyanate, diphenyl sulfide-4,4 '
Diisocyanate, diphenyl ketone-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, and the like, and particularly, diphenylmethane-4, 4'-diisocyanate, toluylene-2,4-diisocyanate, toluylene-2,6-diisocyanate, 2-chlorophenylene-1,4-diisocyanate, naphthalene-2,6-diisocyanate, 2-
Chloro-1,3-diisocyanate and mixtures thereof are preferred. In the present invention, the presence of the tertiary amine is an indispensable substance for increasing the molecular weight, and the object of the present invention cannot be achieved without the tertiary amine reaction promoting action. Third to use
The amount of the tertiary amine can be freely selected within a range of 1 to 300 mol% with respect to the molar ratio of the dicarboxylic acid / diisocyanate used, but is more preferably 5 to 200 mol% in order to make the reaction proceed more smoothly. Representative examples of tertiary amines include:
Aliphatic such as trimethylamine, trieramine, tri-n-propylamine, tri-n-butylamine, tri-iso-butylamine, dimethylethylamine, dimethyl-n-propylamine, dimethyl-iso-propylamine, dimethyl-ter-butylamine Tertiary amines,
Pyridine, 2-methylpyridine, 3-methylpyridine,
4-methylpyridine, 2,3-dimethylpyridine, 2,4,6-
Trimethylpyridine, N, N-dimethylaniline, N, N-diethylaniline, quinoline, 2-methylquinoline, 3-
Methylquinoline, 4-methylquinoline, 2,3-dimethylquinoline, 2,4-dimethylquinoline, 2,6-methylquinoline, aromatic tertiary amines such as isoquinoline, N-methylmorpholine, N-ethylmorpholine, Examples thereof include alicyclic tertiary amines such as N-arylmorpholine, N-methylpiperidine, N-ethylpiperidine, N-arylpiperidine, and triethylenediamine, and particularly, the dissociation constant (PKa) of the amine is 5 or more and 12 or less. Are preferred. Among them, triethylamine, tri-n-propylamine, tri-n-butylamine, 2,4,6-trimethylpyridine, N-ethylmorpholine, triethylenediamine and a mixture thereof are preferred from the viewpoint of catalytic action. Next, typical examples of the aprotic organic polar solvent used in the present invention include N-methyl-2-pyrrolidone and N-methyl-2-pyrrolidone.
Ethyl-2-pyrrolidone, N, N-dimethylacetamide, tetramethylurea, hexamethylphosphoramide,
γ-butyrolactone, dimethyl sulfoxide, sulfolane, N-methylbutyrolactam and the like are preferred. Further, the reaction between the dicarboxylic acid and the diisocyanate of the present invention is preferably performed at 30 ° C to 250 ° C. If the temperature is lower than 30 ° C., an extremely long time is required for the reaction.
A side reaction between the diisocyanate and the solvent, self-condensation of the diisocyanate, and the like may occur, and it may be difficult to increase the degree of polymerization. The reaction temperature is more preferably in the range of 50 ° C to 200 ° C so that the reaction can be performed more quickly and without increasing the degree of polymerization.
The optimum range of the initial monomer concentration depends on the type of the monomer used, but is preferably 5 to 50% by weight. If it is less than 5 wt%, the reactivity may be reduced, and if it exceeds 50 wt%, the stirring effect may be deteriorated due to an increase in the viscosity of the solution and the degree of polymerization may not be increased, or the polymer may be gelled. In consideration of such points, a more preferable monomer concentration is 10 to 40% by weight. In addition, it is optimal that the polymerization reaction is carried out with a stoichiometrically equivalent molar ratio of dicarboxylic acid and diisocyanate in the main polymerization, but the range in which the object of the present invention can be achieved, that is, with respect to 100% of dicarboxylic acid, Polymerization can be performed with 90 to 110 mol% of the diisocyanate, but 95 to 105 mol% is more preferable for more stably increasing the degree of polymerization. The reaction is preferably carried out with stirring for 1 hour to 10 hours, and it is desirable that the solvent used and the tertiary amine are removed of water by rectification or a dehydrating agent. It is better to use dried monomers. The method of adding the monomer, the solvent, and the tertiary amine, the order of addition, and the temperature of addition can be freely selected, and typical methods are shown below. (1) A dicarboxylic acid and a diisocyanate are charged into a reaction vessel at room temperature, and an organic solvent and a tertiary amine are added thereto, and the mixture is heated to a reaction temperature and reacted. (2) A dicarboxylic acid is charged at room temperature and heated to a reaction temperature, and then a diisocyanate and a tertiary amine are added to react. (3) After dissolving each monomer separately in a solvent, they are simultaneously or separately charged into a reactor containing an organic solvent and a tertiary amine. There is no problem if the organic solvent and the tertiary amine are added after the monomer is charged. (4) When a solution prepared by charging a dicarboxylic acid, an organic solvent, and a tertiary amine at room temperature or at a reaction temperature is charged at room temperature, the temperature is raised to the reaction temperature, and the diisocyanate is dissolved in a melt or an organic solvent to obtain an instantaneous or long-term solution. Add over time. However, the method is not limited to these.
The reaction temperature and reaction time vary depending on the electron-withdrawing strength of the dicarboxylic acid used, or the basicity and the amount of the tertiary amine used, but in this reaction form, the electron-withdrawing property of the dicarboxylic acid is generally strong. The higher the basicity of the tertiary amine and the higher the amount of the tertiary amine, the more the reaction can be carried out at a lower temperature, and the polymerization is completed in a shorter time. The amount of the tertiary amine to be added is 1 mol% to 300
It works effectively within the range of mol%, but when it is less than 1 mol%, the reaction activity decreases, and when it is more than 300 mol%, the tertiary amine is a poor solvent for the polymer, so that precipitation of the polymer occurs. Not preferred. Polymerized monomer concentration is 5wt% -50wt%
Can be arbitrarily selected, but in general, it should be determined by the rigidity of the obtained polyamide. Generally, the more the rigidity, the lower the monomer concentration. Method for measuring characteristics and method for evaluating effects The method for measuring characteristic values and the method for evaluating effects according to the present invention are as follows. (1) Intrinsic viscosity (ηinh) C: Number of grams of polymer in 1 dl of solution t _o : Flowing time of solvent only t: Flowing time of solution N-methyl-2- as a solvent using a Ubbelohde viscometer
Measured using pyrrolidone. (2) Solution viscosity The value at a temperature of 30 ° C. was shown using a rotary viscometer. (3) Polymer concentration [Examples] Next, embodiments of the present invention will be described based on examples. Example 1 2-Chloroterephthalic acid was placed in an absolutely dry 500 ml four-necked flask equipped with a stirrer and a Dimroth condenser.
0.15 mol (30.09 g) and N-methyl-2-pyrrolidone 130 m
l is stirred and dissolved under nitrogen aeration. After heating this solution in an oil bath and raising the temperature to 65 ° C, diphenylmethane-4,
0.15 mol (37.54 g) of 4-diisocyanate was charged, the measuring vessel for diisocyanate was washed with 17 ml of NMP and poured into the flask. Further, 0.12 mol (16.74 ml) of TEA (triethylamine) was added to the reaction system using a 20 ml syringe. Ten seconds after the addition of TEA (triethylamine), sudden generation of carbon dioxide gas occurred, the reaction started, and the internal temperature rose to 75 ° C due to the heat of polymerization. After about 10 minutes, the evolution of carbon dioxide gas had subsided considerably, and the internal temperature began to drop to 72 ° C. At this point, the temperature of the oil bath is raised and the internal temperature is controlled to be stable at 95 to 100 ° C. After about 60 minutes of reaction time, the viscosity in the system increases, and if the stirring is further continued for 60 minutes, the solution becomes higher in viscosity. However, after 150 minutes from the start of polymerization, the reaction is almost completed and the viscosity becomes constant. After removing the oil bath, 40 ml of N-methyl-2-pyrrolidone was added to the reaction solution, and the mixture was stirred uniformly to complete the polymerization. The solution was taken out into a 200 ml beaker and the solution properties were measured.
1500 poise / 30 ° C., η _inh = 1.32. Using this dope, cast on a glass plate using an applicator at 150 ° C,
It was dried for 3 minutes, peeled from the glass plate, and heat-treated at 300 ° C. for 1 minute under tension. The resulting film was very tough. Comparative Example 1 Exactly the same reaction was carried out as in Example 1 except that triethylamine was not added, and almost no generation of carbon dioxide was observed even when the temperature was raised to 95 to 100 ° C. Therefore, the temperature was further increased. At an internal temperature of 115 ° C., the generation of carbon dioxide became slightly intense, but after 10 minutes at 115 ° C., the generation of carbon dioxide almost stopped, and the solution was colored black. In this state, the mixture was stirred for 120 minutes to complete the polymerization. The solution had the following properties: PC = 25 wt%, viscosity = 20 poise / 30 ° C., η _inh = 0.18. When cast on a glass plate and dried as in Example 1, it became ragged on the glass plate, Could not be converted. Comparative Example 2 Polymerization was carried out in exactly the same manner as in Example 1 except that CTPA (2-chloroterephthalic acid) was changed to IPA (isophthalic acid). The viscosity increased 30 minutes after the start of the polymerization. The 60-minute elapsed viscosity further increased, and the Weissenberg effect occurred, and the entire solution became gel elastic. N-methyl-2-pyrrolidone was gradually added and the reaction was continued for another 60 minutes to complete the polymerization. The polymerization liquid was taken out to a beaker. At this time, η _inh = 0.75 and viscosity 7
It was 00 poise. When this dope was allowed to stand for one day, the viscosity was remarkably reduced. The measured value was reduced to 350 poise, and η _inh = 0.2. Example 2 Using the same apparatus as in Example 1, 0.12 mol (24.07 g) of 2-chloroterphthalic acid and 0.03 mol (4.98 mol) of terephthalic acid were used.
g) and diphenylmethane-4,4'-diisocyanate.
15 mol (37.54 g) was charged into a flask, and then 148 ml of N-methyl-2-pyrrolidone was charged under a stream of nitrogen and dissolved by stirring at 50 ° C. At this temperature, 0.075 mol (10.5 ml) of triethylamine was injected by syringe. Approximately 30 seconds after the addition of triethylamine, the generation of carbon dioxide vigorously occurred, and the reaction started. The temperature was further increased and the reaction was completed at 90 ° C. for 120 minutes. Η _inh of the obtained polymer solution was 1.43. When a film was prepared using this dope in the same manner as in Example 1, the film was transparent and tough. Comparative Example 3 Using the same apparatus as in Example 1, 0.045 mol (9.03 g) of 2-chloroterephthalic acid and 0.105 mol of terephthalic acid (17.
44G) and diphenylmethane-4,4'-diisocyanate.
15 mol (37.54 g) was charged into the flask, and then 140 ml of N-methyl-2-pyrrolidone was charged under a stream of nitrogen and dissolved by stirring at 50 ° C. At this temperature, 0.075 mol (10.5 ml) of triethylamine was injected by syringe. After the addition of triethylamine, generation of carbon dioxide gas was observed. After a lapse of 2 minutes when the reaction temperature was raised to 90 ° C., the polymer was precipitated, and thereafter no increase in viscosity was observed. This polymer was as low as η _inh = 0.32 and did not form a film. Examples 3-5, Comparative Examples 4-6 As a result of polymerization using various monomers and additives using a 100 ml kneader with a jacket equipped with a condenser, the dicarboxylic acid having an electron-withdrawing group of the present invention
The system using 1 mol% to 300 mol of the tertiary amine could clearly have a higher molecular weight than the composition out of the claims, and a polymer having good storage stability was obtained. Table 1 shows the results. [Effects of the Invention] In the present invention, as a result of polymerizing a monomer having an electron-withdrawing group in an aromatic dicarboxylic acid in an amount of 60 mol% or more and a tertiary amine in combination, a high molecular weight can be obtained with good reproducibility and storage stability. This makes it possible to process the resulting polyamide dope into a fiber or film without any need for complicated steps such as reprecipitation. The thus obtained polyamide dope of the present invention is processed into a film or a fiber, and as a film application, utilizing its heat resistance, a base film for thermal transfer, a base film for magnetic recording, especially a base for thin-leaf high-density magnetic recording tape Optimally used for films. The fibers are preferably used for heat-resistant fibers and tire cords.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-10431 (JP, A) JP-A-61-9421 (JP, A) JP-A-51-10896 (JP, A) JP-A 50-50 45095 (JP, A) JP-A-54-48872 (JP, A) JP-A-58-67723 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 77/00-77 / 12 C08G 18/00-18/87 D01F 6/60 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] General formula, Or an aromatic dicarboxylic acid containing at least 60 mol% of a mixture thereof, wherein X is one or more selected from a halogen group, a nitro group, and a cyano group. L is an integer of 1 to 4. ) And an aromatic diisocyanate represented by the general formula OCN-R ₁ -NCO (where R ₁ is Wherein Y is at least one selected from a halogen group, a nitro group, a cyano group, an alkyl group having 1 to 3 carbon atoms, and an alkoxy group, and Z is -CH
_{2 -, - O -, -} S -, - SO 2 -, It is a kind selected from among. r is an integer of 0 or 1. m, n, and p are integers of 0 to 4, and q is an integer of 0 to 3. ) In an aprotic organic polar solvent in the presence of 1 to 300 mol% of tertiary amine (based on the number of moles of monomers charged).