JPH0742353B2 - Method for producing copolyamide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing a copolyamide, and more particularly to a method for producing a copolyamide suitable for a permselective membrane.

(Prior Art) A solution of one or more organic substances dissolved in a common solvent is pumped to a permselective membrane at a pressure higher than the osmotic pressure of this solution, or the permeation side is set to a low pressure in the solution. There are dialysis method and pervaporation separation method that can selectively permeate and separate the components of, and reverse osmosis that allows water to selectively pass from an aqueous solution of an inorganic salt, but does not pass an inorganic salt.

In these methods, a selectively permeable membrane or a membrane called a reverse osmosis membrane is used. (Hereinafter, both are collectively referred to as a selective permeation film.) Such a selective permeation film is generally made of an organic polymer substance. Its morphology is the same material as a homogeneous film consisting of a dense and homogeneous structure or a composite film in which it is applied to an appropriate support, or a dense surface polymer layer generally having a thickness of 0.1 to 0.3 microns or less There are membranes that have an asymmetric structure consisting of a porous substructure that serves as a thin layer support. This is generally called an asymmetric membrane.

The high water permeability and desalination performance of this asymmetric membrane is dependent on the dense, thin surface polymer layer described above.

Conventionally, cellulose acetate has been industrially used as a material for a selectively permeable membrane. However, this membrane is hydrolysis resistant,
There were problems in terms of microbial resistance and membrane life. On the other hand, aromatic polyamide is known as a new separation membrane material replacing cellulose for the purpose of improving these points (Japanese Patent Publication No. Sho.
53-43540). As a result, hydrolysis, microbial decomposition, and thermal decomposition deterioration have been improved, but there is a drawback that chlorine resistance is very weak. That is, there is a problem that it is very weak against chlorine (oxidizing chlorine) used as a bactericide for water, that is, it lacks chlorine resistance.

In addition, meta-phenylenediamine from Filmtec Co.,
There has been proposed a membrane obtained by cross-linking paraffinylenediamine with an aromatic polyacid halide such as trimesic acid chloride (JP-A-55-147106). It is disclosed that it has not only very good reverse osmosis membrane performance, but also chlorine resistance.

On the other hand, there is known a reverse osmosis anisotropic membrane (see JP-A-49-109271) having good chlorine resistance and made of a copolyamide obtained by reacting a piperazine-based diamine with an aromatic dicarboxylic acid.

(Problems to be Solved by the Invention) The reverse osmosis membrane disclosed in JP-A-55-147106 described above is
Although it has chlorine resistance, it has been found that the chlorine resistance is only short-term and cannot be used for a long time.

In addition, the polyamide using piperazine is N, N-dimethylacetamide, which is usually used for film formation, is hardly soluble in an organic solvent such as N-methylpyrrolidone, and is dangerous to handle, formic acid, and metacresol. It only dissolves in protic solvents. Therefore, it has been found difficult to industrially produce a permselective membrane using this polyamide.

As a result of intensive studies on the deterioration resistance (chlorine resistance) of aromatic polyamides composed of various aromatic diamines to chlorine (chlorine resistance), the chlorine resistance of aromatic polyamides depends largely on the chemical structure of the aromatic amine component used. Found.

As a result of further intensive study on this point, it was found that a copolyamide containing a piperazine-based diamine and a diphenylsulfone-based diamine as an amine component is excellent in film-forming property, selective permeability and chlorine resistance, and has already filed a patent application.

However, since the amine component of the present copolyamide is composed of an aliphatic diamine and an aromatic diamine having different reactivities, it is difficult to obtain a copolyamide having a high degree of polymerization suitable for producing a hollow fiber membrane.

As a result of earnest studies for increasing the degree of polymerization of the present copolyamide, the present inventors have found that the degree of polymerization of the present copolyamide depends on the type of the acid scavenger used, and have reached the present invention.

(Means for Solving Problems) The present invention relates to a mixed diamine component having a molar ratio of piperazine and / or a derivative thereof and a diphenylsulfone diamine of 5/95 to 65/35 to an aromatic dicarboxylic acid chloride compound. It is an improvement in the method for producing an aromatic copolyamide obtained by reacting

The molar ratio of the following diamine compounds (1) and (2) is 95
In producing a copolyamide by reacting a diamine component of / 5 to 35/65 with an aromatic dicarboxylic acid halide compound represented by the following general formula (3) in an organic solvent,
It has been found that when pyridine and / or N, N-dialkylaniline is used as a scavenger of hydrogen chloride produced during the reaction, a copolyamide having a high viscosity can be easily purified.

(However, R ¹ and R ² are hydrogen atoms or hydrocarbon groups having 1 to 12 carbon atoms, R ³ and R ⁴ are hydrogen atoms or monovalent organic groups having no active hydrogen, n ₁ and n ₂ represents 0 or a natural number of 1 to _3. ) (However, R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.) XOC-R-COX (3) (wherein X represents a halogen atom and R represents an organic group having 2 to 15 carbon atoms which may contain a hetero atom.) In particular, in the above formula, diamine compound (1) is 3, 3'-
Diaminodiphenyl sulfone and / or 4,4'-diaminodiphenyl sulfone, diamine compound (2) is piperazine and / or t (trans) -2,5-dimethylpiperazine, and aromatic dicarboxylic acid halide compound (3) In the production of a copolyamide in which R is a phenylene group, pyridine added as an acid scavenger and / or
It has been found that N, N-dialkylaniline is very effective in terms of increasing the viscosity of the polymer and easiness of purifying the polymer.

Examples of the compound represented by the general formula (1) include 3,3′-diaminodiphenyl sulfone, 3,3′-diamino-4,4′-dimethyldiphenyl sulfone and N, N′-dimethyl-3,3 ′. −
Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminodiphenyl sulfone, N, N'-dimethyl-4,4'-diaminodiphenyl sulfone, 3 3,3'-dinitro-4,4'-diaminodiphenyl sulfone and the like can be mentioned, and particularly preferred compounds are 3,3'-diaminodiphenyl sulfone and 4,4'-
It is diaminodiphenyl sulfone.

Examples of the compound represented by the general formula (2) include piperazine,
2-methylpiperazine, t (trans) -2,5-dimethylpiperazine, cis-2,5-dimethylpiperazine, 2,6-
Dimethylpiperazine, 2,3,5-trimethylpiperazine,
2,2,3,3,5,5,6,6-octamethylpiperazine, 2,2,5,5-
Tetramethylpiperazine, 2,2,3,5,5,6-hexamethylpiperazine, 2-ethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2,2,3,5,5 , 6
-Hexaethylpiperazine, 2,3,5,6-tetraethylpiperazine, 2-propylpiperazine, 2,6-dipropylpiperazine, 2,3,5-tripropylpiperazine, 2,3,5,6
-Tetra-n-propylpiperazine, 2-butylpiperazine, 2,5-di-n-butylpiperazine, 2,5-di-tert
-Butylpiperazine, 2,3,5-tri-n-butylpiperazine, 2-pentylpiperazine, 2-decylpiperazine, 2,5-divinylpiperazine, 2,5-diphenylpiperazine, 2-phenylpiperazine, 2, 3,5,6-tetraphenylpiperazine, 2-naphthylpiperazine, 2,5-dinaphthylpiperazine, 2-tolylpiperazine, 2,5-ditolylpiperazine, 2,3,5,6-tetratolylpiperazine, etc. Can be mentioned. Particularly preferred diamine compounds (2) are piperazine and t-2,5-dimethylpiperazine.

Examples of the acid halide compound (3) in the present invention include phthalic acid, isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, 1,2-naphthalene dicarboxylic acid, 1,3-
Naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid acid,
Examples thereof include aromatic dicarboxylic acid halide compounds such as 2,6-naphthalene dicarboxylic acid and 2,7-naphthalene dicarboxylic acid. Of these, isophthalic acid dichloride and terephthalic acid dichloride are particularly preferable.

The above aromatic dicarboxylic acid halide compounds can be mixed and used in any proportion.

The copolymerization ratio of the compound represented by the general formula (1) and the diamine compound represented by the general formula (2) is 95/5 to 35/65 in terms of molar ratio.
Is.

When the amount of the diamine compound (2) is more than 65 mol%, it is difficult to obtain a highly viscous copolyamide. The preferred amount of diamine compound (2) is in the range of 10 to 60 mol%, and particularly preferred
It is in the range of 10 to 40 mol%.

The copolyamide of the present invention can be synthesized by the following solution polymerization method.

As the solvent used in the solution polymerization method, various organic solvents can be used, but an amide solvent is preferably used.
Preferred solvents include N-methyl-2-pyrrolidone,
Hexamethylphosphoramide, N, N'-dimethylacetamide, N, N'-dimethylformamide and mixtures thereof can be mentioned. Further, methylene chloride, chloroform, 1,2-dichloroethane, 1,
It is also possible to mix chlorine-based solvents such as 1,2-trichloroethane, 1,1,2,2-tetrachloroethane and chlorobenzene.

The above-mentioned solvents used for the polymerization must be sufficiently dehydrated in advance with a dehydrating agent such as distillation or molecular sieve. The water content of the solvent used in the polymerization reaction of the present invention is 50.
0ppm or less, preferably 300ppm or less, particularly preferably 150p
Below pm.

Further, pyridine and / or N, N-dialkylaniline is used as the acid scavenger. As the N, N-dialkylaniline compound, N, N-dimethylaniline and N, N-diethylaniline are particularly preferable from the viewpoints of increasing the viscosity of the polymer and easiness of purification.

The water content of the acid scavenger used in the polymerization reaction of the present invention is 500 ppm or less, preferably 300 ppm or less, and particularly preferably 150 ppm or less. The acid scavenger used is preferably purified in advance by distillation.

As a general polymerization method of solution polymerization, a mixture of diamine compounds (1) and (2) is dissolved in the amide solvent or the mixed solvent. The concentration of the charged monomer in the solvent is 10 to 50% (wt monomer / vol solvent), preferably
20-40%.

Further, a predetermined amount of pyridine and / or N, N-dialkylaniline compound is added to the mixed system as a scavenger of hydrogen chloride generated during the reaction. The addition amount of pyridine as an acid scavenger is not particularly limited, but basically it is preferably 1.0 to 3.0 times mol, more preferably 1.0 to 2.0 times mol of the theoretical amount of hydrogen chloride generated during the reaction.

If the amount of pyridine added as an acid scavenger is large relative to the reaction solvent used, pyridine acts as a poor solvent for the polymer, making the solution non-uniform during the reaction, and increasing the viscosity and hindering the purification process. .

The ratio of the amount of pyridine to the amount of the reaction solvent is 1/2 or less, preferably 1/3 or less in volume ratio.

As for the amount of N, N-dialkylaniline compound added, the theoretical amount of hydrogen chloride generated during the reaction is 1.0 to 1.2.
A double mole is preferable. If the amount added is 1.0 or less, the effect as a hydrogen chloride scavenger is reduced, and the viscosity of the resulting copolyamide is also reduced.

On the other hand, when it is 1.2 or more, the polymer becomes insoluble in the reaction solvent and the reaction system becomes non-uniform. As a result, it becomes difficult to purify the polymer. Furthermore, the viscosity of the obtained polymer also decreases with the addition amount.

When the amine compound is dissolved in a mixed solvent of the above solvent and an acid scavenger to form a uniform solution, an appropriate solvent may be added or the mixed solvent may be heated for the purpose of improving solubility. Is also possible. The solvent for promoting the solubility needs to be sufficiently dehydrated in advance by distillation or a desiccant.
The heating temperature may be any temperature as long as it does not decompose the solvent used and the amine compound, but the most preferable temperature is room temperature.

Then, the mixed solution is cooled with a suitable refrigerant to bring the temperature of the mixed solution to -10 ° C to 20 ° C, preferably -5 ° C to 10 ° C.
Water and / or ethylene glycol are generally and preferably used as the refrigerant, but the method is not particularly limited.

Next, the dicarboxylic acid halide is added to the cooled mixed liquid of the diamine compound, the acid scavenger and the reaction solvent with stirring, and the stirring is continued for an appropriate time. The form of the dicarboxylic acid halide at the time of addition may take any form such as a solid state (powder, flake or pellet), a solution dissolved in a suitable solvent, or a state melted by heating. Although possible, it is preferably in the solid state.

The rate of addition of the dicarboxylic acid halide to the mixed solution is
Depending on the temperature of the reaction solution at the time of addition, the temperature of the reaction system must be continuously adjusted to 70 ° C by the heat of reaction (heat of polymerization), preferably the addition rate of the dicarboxylic acid halide must be adjusted not to exceed 40 ° C. I won't. The stirring speed at the time of adding the dicarboxylic acid halide affects the degree of polymerization of the polymer produced, and the higher the stirring speed, the higher the degree of polymerization of the obtained polymer, which is preferable from the viewpoint of the physical properties of the polymer.

After the addition of the dicarboxylic acid halide, stirring is continued for about 30 minutes to 1 hour under the above cooling. The stirring speed at this time may be any speed, but it is preferably as high as possible.

After the reaction under cooling as described above, subsequently, at room temperature, about 1
The polymerization reaction is continued for 2 hours. The stirring speed at this time may be any speed, but it is preferable that the stirring speed is as high as possible in order to obtain a highly viscous polymer.

The mode of the polymerization reaction system generally depends on the type and concentration of the acid scavenger, but when the pyridine and N, N-dialkylaniline compounds mentioned in the present invention are used as the acid scavenger, the reaction system is polymerized. The feature is that the reaction system in and after polymerization becomes a transparent homogeneous solution. Therefore, it is very convenient when the polymerization reaction solution is put into a poor solvent for the polymer to solidify and purify the polymer.

Further, since the reaction system is constantly homogeneous during the polymerization, a polymer having a high degree of polymerization can be obtained.

On the other hand, when an acid scavenger other than the present invention, such as triethylamine, is used, the produced polymer becomes insoluble in the reaction system, and the reaction system during and after the polymerization becomes a heterogeneous solution. For this reason,
The reaction active terminal is easily deactivated, resulting in a decrease in polymer viscosity. Further, it is difficult to purify the polymer by the above-mentioned precipitation method, and when this is carried out, a good solvent for the polymer, for example, N, N-dimethylacetamide, N-methylpyrrolidone or the like is added to the reaction system. Dissolve the polymer,
The system must be homogenized before proceeding. Thus, the production method of the present invention is not only effective in increasing the viscosity of the polymer, but also facilitates the purification of the polymer.

At the time of polymerization, the mixture solution is suitable for neutralizing hydrogen halide generated during the polymerization before, during, and after the polymerization and / or for facilitating the dissolution of the polymer in a reaction solvent. It is also possible to add substances.

Examples of such inorganic compounds include lithium chloride,
Preferred examples include calcium chloride, potassium chloride, lithium carbonate, lithium oxide, lithium hydroxide, calcium hydroxide, calcium carbonate and the like. Lithium chloride, calcium chloride, potassium chloride and the like can be added before the polymerization for the purpose of accelerating the dissolution of the polymer, but the others are preferably added after the polymerization for the purpose of neutralizing generated hydrogen halide. . Further, as an organic compound having such an effect, propylene oxide is mentioned as a preferable example. The substance can be added before and / or after the polymerization.

If necessary, a terminal terminating agent can be used as the other additive, and as the terminal terminating agent, a compound having only one group that reacts with an amino group and an acid halide group is suitable.

After the polymerization reaction, the obtained solution is mixed with a poor solvent for the polymer such as methanol and water to take out the polymer as a solid. Further, filtration of solid polymer and washing with water and methanol should be repeated to remove the solvent, acid scavenger, hydrochloric acid and oligomer adsorbed on the polymer as much as possible. Thoroughly washed polymer at 130 ℃ -150
The copolyamide of the present invention can be obtained by vacuum drying at ° C.

The amount of residual hydrochloric acid in the polymer purified in this way is 500 p
It should be below pm, preferably below 200 ppm.

(Effect of the Invention) The method for producing the novel copolyamide of the present invention is characterized in that not only a high-viscosity polymer can be obtained as shown in Examples described later, but also the reaction system is uniform, which is advantageous for purification. is there.

(Examples) Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

Example 1 Synthesis of poly (isophthaloyl-4,4'-diaminodiphenylsulfone / piperazine (80/20)) copolymer Piperazine 1.72 g (0.02 mol), 4,4'-diaminodiphenyl sulfone 19.8 g (0.08) mol) nitrogen introduction tube, thermometer,
Place in a 500 ml four-necked flask equipped with a stirrer under a nitrogen stream. In addition, pyridine is used as an acid scavenger in this system.
28 ml (0.2 mol) and 200 ml of N-methylpyrrolidone (NMP) as a reaction solvent are added to dissolve the monomer.

Isophthalic acid chloride 20.48 g while cooling the entire reaction system with ice
(0.10 mol) was slowly added under a nitrogen stream. The reaction system was stirred for about 60 minutes under ice cooling and for about 1 hour at room temperature. At this time, the reaction system was a red-orange homogeneous solution.

Then, the reaction solution is added to 1500 ml of methanol to precipitate the polymer. A series of purification steps of grinding the polymer with a household mixer, filtering, and washing with water were repeated several times to remove unreacted substances in the polymer and remove the solvent. Finally, the polymer was washed with methanol and dried under vacuum at about 130 ° C. for about 48 hours.

The reduced viscosity (ηsp / C) of the copolyamide is 0.79 (0.5 g / dlN
MP, 30 ° C).

Examples 2, 3 Synthesis of poly (isophthaloyl-4,4'-diaminodiphenyl sulfone / piperazine (80/20)) copolymer In Example 1, the amount of pyridine was 1.35 times the theoretically generated amount of hydrogen chloride. Was carried out in the same manner as in Example 1 except that the molar ratio was 1.75 times.

All the reaction systems were homogeneous solutions, and the reduced viscosities of the obtained polymers were 1.17 and 1.30, respectively, indicating high polymers.

Examples 4, 5, 6 Synthesis of poly (isophthaloyl-4,4'-diaminodiphenyl sulfone / piperazine (80/20)) copolymer In Examples 1, 2 and 3, the reaction solvent was replaced with NMP.
The same procedure as in Examples 1, 2 and 3 was carried out except that N, N-dimethylacetamide was used.

The reaction systems were all homogeneous solutions, and the reduced viscosities of the obtained polymers were 0.77, 1.19, and 1.30, which were high polymers.

Comparative Examples 1 and 2 In Example 1, no acid scavenger was used and the reaction solvent was NMP.
Alternatively, the same procedure as in Example 1 was carried out except that DMAc was used.

Although the reaction systems were homogeneous solutions, the reduced viscosities of the obtained polymers were 0.37 and 0.52, which were low polymers.

Comparative Examples 3, 4, 5 In all of Examples 4, 5, 6 except that triethylamine (TEA) was used instead of the acid scavenger Py,
It carried out like 5 and 6.

The reaction systems were all heterogeneous solutions, and the reduced viscosities of the obtained polymers were 0.64, 0.41 and 0.32, respectively, indicating low polymers. Further, as the amount of TEA added increased, the reduced viscosity of the produced polymer also decreased.

Examples 7,8,9 Synthesis of Poly (terephthaloyl-3,3'-diaminodiphenylsulfone / piperazine) Copolymer In Example 1, instead of 4,4'-diaminodiphenylsulfone, isophthalic chloride and pyridine. To
The same procedure as in Example 1 was carried out except that 3,3′-diaminodiphenyl sulfone, terephthalic acid chloride and diethylaniline were used, and the amounts of piperazine to the total amount of diamine components were 20, 30, and 50 mol%. .

The reaction solutions were all homogeneous solutions, and the reduced viscosities of the obtained polymers were 0.79, 0.86 and 0.77.

Examples 10, 11, 12, 13 Synthesis of poly (terephthaloyl-4,4'-diaminodiphenyl sulfone / piperazine) copolymer In Example 7, instead of 3,3'-diaminodiphenyl sulfone, 4,3 Using 4'-diaminodiphenyl sulfone, the amount of piperazine to the total amount of diamine components was 10,
All were carried out in the same manner as in Example 7 except that the content was 20, 30, 40 mol%.

The reaction solutions were all homogeneous solutions, and the obtained polymers had high reduced viscosity of 1.18, 1.35, 1.10, 0.99.

Example 14 Synthesis of poly (terephthaloyl-3,3'-diaminodiphenylsulfone-4,4'-diaminodiphenylsulfone / piperazine) copolymer In Example 7, instead of 3,3'-diaminodiphenylsulfone The same procedure as in Example 7 was carried out except that 3,3'-diaminodiphenyl sulfone and 4,4-diaminodiphenyl sulfone were used in equal amounts.

The reaction solution was a homogeneous solution, and the polymer thus obtained had a high reduced viscosity of 1.05.

Comparative Examples 6 and 7 The procedure of Example 7 was repeated except that the acid scavenger DEA was not used or TEA was used in place of the acid scavenger DEA.

When the acid scavenger was not used, the reaction solution was a homogeneous solution, but the polymer obtained had a low reduced viscosity of 0.30. In the latter case, the reaction solution was a heterogeneous solution, and the polymer obtained had a low reduced viscosity of 0.17.

Examples 15, 16, 17 Synthesis of Poly (terephthaloyl-3,3'-diaminodiphenylsulfone / trans-2,5-dimethylpiperazine) Copolymer In Examples 7, 8 and 9, instead of piperazine, trans was used. Using -2,5-dimethylpiperazine, except that the amount of trans-2,5-dimethylpiperazine with respect to the total amount of diamine components was 20, 30, 50 mol%, Example 7,
It carried out like 8 and 9.

The reaction solutions were all homogeneous solutions, and the reduced viscosities of the obtained polymers were 0.73, 0.59 and 0.50.

Example 18 Synthesis of poly (terephthaloyl-3,3'-diaminodiphenylsulfone / trans-2,5-dimethylpiperazine) copolymer In Example 15, except that dimethylaniline was used instead of the acid scavenger DEA. Was performed in the same manner as in Example 15.

The reaction solution was a homogeneous solution, and the polymer obtained had a reduced viscosity of 0.53.

Examples 19, 20, 21, 22 Poly (terephthaloyl-3,3'-diaminodiphenylsulfone / trans-2,5-dimethylpiperazine) Copolymers Synthesis In Examples 10, 11, 12, 13 the piperazine Instead of using trans-2,5-dimethylpiperazine, the same procedure as in Examples 10, 11, 12, and 13 was performed.

The reaction solutions were all homogeneous solutions, and the obtained polymers had high reduced viscosities of 1.04, 0.91, 0.86 and 0.72.

Examples 23, 24 Synthesis of Poly (terephthaloyl-3,3'-diaminodiphenylsulfone-4,4'-diaminodiphenylsulfone / trans-2,5-dimethylpiperazine) Copolymer Instead of 3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone and 4,4'-diaminodiphenyl sulfone are added at 24:56 or 4
The same procedure as in Example 15 was carried out except that the molar ratio was 0:40.

The reaction solution was a homogeneous solution, and the obtained polymer had high reduced viscosity of 0.83 and 0.70.

Comparative Example 8 The procedure of Example 15 was repeated except that TEA was used instead of the acid scavenger DEA.

In this case, the reaction solution was a heterogeneous solution, and the polymer thus obtained had a low reduced viscosity of 0.25.

Claims (3)

[Claims] 1. A diamine component having a molar ratio of the following diamine compounds (1) and (2) of 95/5 to 35/65 and an aromatic dicarboxylic acid halide compound represented by the following general formula (3). And an organic solvent and pyridine and / or N, N-
A method for producing a copolyamide, which comprises polymerizing in the presence of a dialkylaniline. (However, R ¹ and R ² are hydrogen atoms or hydrocarbon groups having 1 to 12 carbon atoms, R ³ and R ⁴ are hydrogen atoms or monovalent organic groups having no active hydrogen, n ₁ and n ₂ represents 0 or a natural number of 1 to _3. ) (However, R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.) XOC-R-COX (3) (wherein X represents a halogen atom and R represents an organic group having 2 to 15 carbon atoms which may contain a hetero atom). 2. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ ,
The method for producing a copolyamide according to claim 1, wherein R ¹² is a hydrogen atom and R is a phenylene group. 3. R ¹ , R ² , R ³ , R ⁴ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹² are hydrogen atoms, R ⁵ and R ¹¹ are methyl groups, and R The method for producing a copolyamide according to claim 1, wherein is a phenylene group.