JPH11343338A - Production of alpha, omega-aminocarboxylic acid and polymerization of lactam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aminocarboxylic acid in high yields within a short time by hydrolyzing a lactam in a supercritical state. SOLUTION: Water is added to a lactam represented by the formula, 0.00001-10 wt.%, based on the lactam, acidic catalyst such as sulfuric acid is further added to the mixture, and the resultant mixture is subjected to hydrolysis at a critical temperature of 374 deg.C or above and a critical pressure of 220 kg/cm<2> or above. After the reaction, the reaction mixture is filtered to obtain an α,ω- aminocarboxylic acid. This product is then added to a lactam, and the resulting mixture is adjusted to a moisture content of 0.5 wt.% or below, and then polymerized by heating to 100-400 deg.C to obtain a polylactam having a relative viscosity of 1.7-5.5 as measured in 98% sulfuric acid in a concentration of 1% at 25 deg.C. If necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a mold release agent, or the like, are added to the polymerization system. The lactam is exemplified by γ-butyrolactam, ε-caprolactam, or ω-laurolactam. In the formula, R<1> is hydrogen or a 1-18C monovalent organic group; an R<2> is a 2-20C divalent hydrocarbon group which may be substituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an α, ω-aminocarboxylic acid by hydrolysis of a lactam and a method for polymerizing a lactam using the α, ω-aminocarboxylic acid. By using the manufacturing method of the present invention, α, ω
-The aminocarboxylic acid can be produced with high purity and high yield. Further, the polymerization time can be greatly reduced by adding the obtained product to a lactam for polymerization.

[0002]

2. Description of the Related Art Many lactam polymerization methods have been proposed so far, but a polymerization widely used industrially is a polymerization using water as a catalyst (sometimes referred to as an initiator). Water-catalyzed polymerization of lactams can be generally used for various lactams, and ε-caprolactam, ω-laurolactam, ω-undecalactam, etc. are subjected to polymerization, and nylon 6 and nylon 6, respectively. 1
2. Used as nylon 11. Water-catalyzed polymerization of lactams is not only applicable to many lactams, but also has many industrial advantages without using special reagents and because the catalyst is an inexpensive and safe compound called water. Widely applied.

[0003] However, this polymerization method cannot be said to have a sufficiently high polymerization rate and has a long polymerization time. For this reason, a large-scale polymerization facility is required to obtain a large amount of polymer industrially.

In order to solve these problems, many studies and proposals have been made. As means for improving the polymerization rate and efficiently obtaining a large amount of polymer in a small polymerization tower,
Japanese Patent Application Laid-Open No. 49-120992 discloses a method of returning a part of the reaction intermediate in the middle part of the polymerization tower to the top of the column, and obtaining an anhydrous lactam monomer after reaching an equilibrium represented by Japanese Patent Application Laid-Open No. 50-24394. There has been proposed a method of adding and further performing polymerization, a method of lowering the temperature of a post-polymerization tower compared to a pre-polymerization tower as represented by JP-B-51-2960, and the like. Also, a method of adding a mineral acid represented by phosphoric acid (Polyamide Handbook, Osamu Fukumoto, Nikkan Kogyo Shimbun, 198
8 years, pp. 56-57), a method of adding a hydrolysis product of a lactam represented by aminocaproic acid (Polyamide Handbook, Osamu Fukumoto, edited by Nikkan Kogyo Shimbun, 1988)
Year, pages 56-57) are also known.

[0005] Among these, the simplest method is to add a hydrolysis product of a lactam represented by aminocaproic acid, that is, an α, ω-aminocarboxylic acid.

As a method for producing an α, ω-aminocarboxylic acid represented by aminocaproic acid, for example, a method of hydrolyzing a lactam by heating it in the presence of an acidic catalyst or a basic catalyst (JP-B-29-7577) , Organic S
yntheses, 17, 7-8, 1937, Organic S
syntheses, 32, 13-16, 1952).

[0007]

However, the method of heating and hydrolyzing a lactam in the presence of an acidic catalyst or a basic catalyst has a problem that the reaction time is long because the reaction rate is low. Further, since a large amount of catalyst is required, a purification step is required, and it has not been possible to directly introduce the reaction solution into the lactam polymerization step.

As described above, since there is no inexpensive method for producing α, ω-aminocaproic acid, the present situation is that the method is not practiced on an industrial scale.
There has been a demand for a method for producing α, ω-aminocarboxylic acid with high purity and high yield.

[0009]

Means for Solving the Problems The present inventors have proposed α,
As a result of an intensive search for an inexpensive method for producing ω-aminocarboxylic acid, the present inventors have found that lactams are easily hydrolyzed in a supercritical state and that there are few by-products.

That is, the present invention provides a method for producing an α, ω-aminocarboxylic acid which hydrolyzes a lactam represented by the following formula (1) in a supercritical state, and a method for producing a lactam represented by the following formula (1): This is a lactam polymerization method in which hydrolysis is performed in a critical state, and the obtained product is added to a lactam represented by the following formula (1) and polymerized.

[0011]

Embedded image (Wherein, R ¹ represents hydrogen or a monovalent organic group having 1 to 18 carbon atoms. R ² represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and has a substituent. May be.)

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, “weight” means “mass”.

Lactam is a cyclic compound having an amide group (-NHCO-) in the ring. The lactam used in the present invention is a compound represented by the following formula (1).

Embedded image (Wherein, R ¹ represents hydrogen or a monovalent organic group having 1 to 18 carbon atoms. R ² represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and has a substituent. The lactam represented by the formula (1) may be unsubstituted or may have a substituent. Examples of the substituent include an alkyl group,
Examples thereof include an alkenyl group, an aryl group, and an aralkyl group. Also, a mixture of two or more of these lactams may be used.

Specific examples of these lactams include β-propiolactam (2-azetidinone), γ-butyrolactam (2-pyrrolidinone), and δ-valerolactam (2-
Piperidone), ε-caprolactam (2-oxahexamethyleneimine), 2-azacyclooctanone, 2-azacyclononanone, 2-azacyclodecanone, 2-azacycloundecanone, 2-azacyclododecanone, Laurolactam (2-azacyclotridecanone), 2-azacyclotetradecanone, 2-azacyclopentadecanone, 2-azacyclohexadecanone, 2-azacycloheptadecanone, 2-azacyclooctadecanone, 2-azacyclononadecanone, 2-azacycloeicosanone,
2-azacyclopheneicosanone, 2-azacyclodocosanone, 2-azacyclotricosanone, 2-azacyclotetracosanone, 2-azacyclopentacosanone, 2-
Azacyclohexacosanone, 2-azacycloheptacosanone, 2-azacyclooctacosanone, 2-azacyclononacosanone, 2-azacyclotriacontanone, N-alkyl-substituted and N-alkenyl-substituted lactams , An N-aryl substituent, an N-aralkyl substituent, an alkyl group, an alkenyl group,
Examples include a substituted lactam having an aryl group or an aralkyl group, or a mixture of two or more of these lactams.

Among these lactams, β-propiolactam (2-azetidinone), γ-butyrolactam (2-pyrrolidinone), δ-valerolactam (2-piperidone), ε-caprolactam (2-oxahexamethyleneimine) , 2-azacyclooctanone, 2-azacyclononanone, 2-azacyclodecanone, 2-azacycloundecanone, 2-azacyclododecanone, laurolactam (2-azacyclotridecanone), and N −
Alkyl-substituted, N-alkenyl-substituted, N-aryl-substituted, N-aralkyl-substituted, substituted lactams having an alkyl, alkenyl, aryl, or aralkyl group on a carbon atom of these lactams, or two of these lactams Mixtures of more than one species are preferred. Among them, β-propiolactam (2-azetidinone), γ-butyrolactam (2-pyrrolidinone), δ-valerolactam (2-piperidone), ε-caprolactam (2-oxahexamethyleneimine), 2-azacyclododeca Non-, laurolactam (2-azacyclotridecanone) and a mixture of two or more of these are preferable, and in particular, ε-caprolactam,
ω-Undecalactam, ω-laurolactam or mixtures thereof are preferred.

In the present invention, the supercritical state refers to a state in which the temperature exceeds a critical temperature and a critical pressure.

The supercritical fluid used in the present invention is not particularly limited as long as it becomes a reaction solvent in a supercritical state, and examples thereof include carbon dioxide, ethane, ethylene, propane, pentane, chlorofluorocarbon and water. Among them, carbon dioxide is a stable and harmless inert gas, and easily forms a supercritical state even at a relatively low temperature, and is preferably used. In the case of carbon dioxide, critical temperature 31 ° C, critical pressure 75.3kg / cm
² Further, water that is advantageous for hydrolysis is also preferably used. In the case of water, critical temperature 374 ° C, critical pressure 220kg
/ Cm ² . The supercritical fluid used in the present invention is D
It may be used in a state of being mixed with a solvent used for general chemical reactions such as MSO, DMF, alcohols, halogenated solvents and the like. The mixing ratio may be arbitrary.

The hydrolysis of the lactam in the supercritical state in the present invention is carried out as follows.

When supercritical water is used, the reaction temperature is 374
C. or higher, preferably 380 to 500C, more preferably 380 to 450C. The pressure is a saturation pressure necessary to maintain a liquid phase in a region below the critical temperature, and a pressure higher than the critical pressure is necessary in a region above the critical temperature, and is preferably a saturation pressure or a critical pressure or 10 kg above the pressure. / Cm ² higher pressure. If the temperature of the water for dissolving the lactam is too low, its solubility will be low, while if the temperature of the water is too high, the lactam will decompose, which is not preferable. The amount of water used in the reaction depends on the reaction temperature, but an amount that can completely dissolve the lactam or more is used.

After completion of the reaction, the reaction solution is generally heated at 300 ° C.
Hereinafter, preferably 100 to 300 ° C., more preferably 1 to 300 ° C.
Cool to a temperature range of 80-270 ° C. Α, ω obtained
-Methods for separating aminocarboxylic acid include sedimentation separation,
In addition to centrifugation, filtration, and the like, ordinary separation methods such as drying by evaporation of water and solvent extraction can be used. Alternatively, the obtained reaction solution may be directly introduced into a lactam polymerization apparatus.

As another method, a method of adding a lactam and a small amount of water to a supercritical state of carbon dioxide to carry out hydrolysis can also be adopted.

In the hydrolysis of the lactam of the present invention,
Although the desired aminocarboxylic acid can be obtained in a high yield without a catalyst, a high yield can be achieved in a short time by adding a trace amount of an acidic catalyst as a reaction catalyst. Specific examples of the catalyst include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, a compound containing a phosphoric acid group, a compound containing a sulfonic acid group, carboxylic acid, boron trifluoride, and a Lewis acid such as aluminum chloride. Can be

The amount of the catalyst varies depending on the type of the catalyst and the reaction conditions.
It is selected from the range of 0001 to 10% by weight, preferably 0.0001 to 5% by weight, more preferably 0.0005 to 1% by weight.

By adding a product containing an aminocarboxylic acid obtained by the method of the present invention to a lactam, the lactam can be polymerized in a short time. As a device used for the polymerization of lactam, any device such as a device used for producing polycaprolactam from a lactam containing water may be used.

In the present invention, the polymerization temperature at the time of producing a polylactam by lactam polymerization depends on the type of lactam used, but is usually 100 to 400 ° C., preferably 140 to 350 ° C., more preferably 160 to 3 ° C.
20 ° C. If the polymerization temperature is too low, the time required for polymerization becomes extremely long, and the viscosity of the polymer at the time of discharge becomes high, which makes it difficult to discharge. If it is too high, the polycaprolactam tends to deteriorate and the yield tends to decrease.

In the method of the present invention, when polymerizing a lactam, a product containing an aminocarboxylic acid obtained by hydrolyzing the lactam in a supercritical state is added to the lactam, and the water content in the mixture is reduced to 0%. The polylactam can be polymerized by adjusting to about 0.5% by weight or less and heating to the above temperature.

In particular, the amount of water in the raw material when polymerizing caprolactam is preferably 0.5% by weight or less, more preferably 0.4% by weight or less, and further preferably 0.3% by weight or less. If the water content is too large, a cyclic oligomer is likely to be generated during polymerization.

When a product containing α, ω-aminocarboxylic acid obtained by hydrolyzing a lactam in a supercritical state is added to the lactam, and a polylactam is produced from this mixture, a lactam / water composition Rather than directly from
The polymerization can be terminated in a short time. Therefore,
It is possible to shorten the polymerization time.

The degree of polymerization of the polylactam obtained in the present invention is not particularly limited, but its relative viscosity (ηr) measured at 98% sulfuric acid concentration of 1% at a temperature of 25 ° C. is in the range of 1.7 to 5.5. Is preferable, the range of 1.8-5.0 is more preferable, and the range of 1.9-4.8 is still more preferable.

When the monomer or oligomer remains after polymerization, the polylactam obtained in the present invention can be removed by means of extraction, heating, reduced pressure or the like, if necessary.

At the time of polymerization, an antioxidant and a heat stabilizer (for example, hindered phenol type, hydroquinone type, phosphite type and substituted products thereof, copper iodide, potassium iodide) as long as the object of the present invention is not impaired. Such),
UV absorbers (eg, resorcinol, salicylate, benzotriazole, benzophenone, hindered amine, etc.), lubricants and release agents (montanic acid and its salts, esters, half esters, stearyl alcohol, stearylamide and polyethylene wax) Colorants including stearic acid, sodium stearate, barium stearate, metal stearate such as aluminum stearate, dyes (eg, nigrosine) and pigments (eg, cadmium sulfide, phthalocyanine, carbon black, titanium oxide, etc.), Ordinary additives such as a plasticizer and an antistatic agent can be added to impart predetermined characteristics.

[0032]

The present invention will be described in more detail with reference to the following examples. In addition, weight means mass. As the caprolactam, a crystal industrially used for polymerization was used as it is.

In the examples, relative viscosity ηr, terminal amino group concentration [NH ₂ ], terminal carboxyl group concentration [COOH],
The quantification of α, ω-aminocarboxylic acid was performed as follows.

(1) Relative viscosity ηr A 98% sulfuric acid solution having a concentration of 0.01 g / mL was prepared and measured at 25 ° C. using an Ostwald viscometer.

(2) Terminal amino group concentration [NH ₂ ] 0.5 g of a sample was mixed with phenol / ethanol = 84/1.
The solution was dissolved in 25 mL of a 6 (wt%) mixed solution at room temperature, and titrated with N / 50N hydrochloric acid using thymol blue as an indicator.

(3) Terminal carboxyl group concentration [COO
H] 0.5 g of the sample was added to 20 mL of benzyl alcohol 19
Dissolve at 5 ° C and use phenolphthalein as an indicator
It was determined by titration with a / 50 N potassium hydroxide / ethanol solution.

(4) Determination of α, ω-aminocarboxylic acid 15 g of the reaction solution was diluted with water to 50 mL, and the carboxyl group was titrated using a potentiometric titrator AT200 manufactured by Kyoto Electronics Co., Ltd. The amount of α, ω-aminocarboxylic acid was determined.

Example 1 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam and 30 g of water and reacted at 380 ° C. and 250 kg / cm ² for 10 hours. Next, cool the reactor and take out the contents,
Aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 92% of the charged caprolactam was converted to aminocaproic acid. Aminocaproic acid was synthesized in high yield by hydrolyzing caprolactam in the supercritical state.

Example 2 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 14 g of water and 420 g of carbon dioxide, and heated at 250 ° C. and 150 kg / cm ^2.
Was reacted for 10 hours. Next, the reactor was cooled and the contents were taken out, and aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 91% of the charged caprolactam was converted to aminocaproic acid. Aminocaproic acid was synthesized in high yield by hydrolyzing caprolactam in the supercritical state.

Example 3 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 30 g of water and 0.01 g of phosphoric acid and reacted at 380 ° C. and 250 kg / cm ² for 3 hours. Next, the reactor was cooled and the contents were taken out, and aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 94% of the charged caprolactam was converted to aminocaproic acid. By using an acidic catalyst when hydrolyzing caprolactam in a supercritical state, aminocaproic acid could be synthesized in higher yield.

Example 4 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 14 g of water, 420 g of carbon dioxide and 0.01 g of phosphoric acid.
The reaction was carried out at 150 ° C. and 150 kg / cm ² for 3 hours. Next, the reactor was cooled and the contents were taken out, and aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 93% of the charged caprolactam was converted to aminocaproic acid. By using an acidic catalyst when hydrolyzing caprolactam in a supercritical state, aminocaproic acid could be synthesized in higher yield.

Comparative Example 1 Caprolactam (30 g) and water (30 g) were placed in a 600 cc stainless steel autoclave.
And reacted at 200 ° C. and 100 kg / cm ² for 10 hours. Next, the reactor was cooled and the contents were taken out, and aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 10% of the charged caprolactam was converted to aminocaproic acid. Due to the lack of supercritical state, aminocaproic acid could not be synthesized in high yield.

Comparative Example 2 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 14 g of water and 420 g of carbon dioxide, and reacted at 20 ° C. and 40 kg / cm ² for 10 hours. The content was taken out of the reactor, and aminocaproic acid contained in the content was quantified by potentiometric titration. As a result, 5% of the charged caprolactam was converted to aminocaproic acid. Due to the lack of supercritical state, aminocaproic acid could not be synthesized in high yield.

Comparative Example 3 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 30 g of water and 0.01 g of phosphoric acid, and reacted at 200 ° C. and 100 kg / cm ² for 10 hours. Next, the reactor was cooled and the contents were taken out, and aminocaproic acid contained in the contents was quantified by potentiometric titration. As a result, 14% of the charged caprolactam was converted to aminocaproic acid. Since it was not in a supercritical state, aminocaproic acid could not be synthesized in high yield even when an acidic catalyst was used.

Comparative Example 4 A 600 cc stainless steel autoclave was charged with 30 g of caprolactam, 14 g of water, 0.01 g of phosphoric acid, and 420 g of carbon dioxide.
The reaction was carried out at 40 ° C. and 40 kg / cm ² for 10 hours. The content was taken out of the reactor, and aminocaproic acid contained in the content was quantified by potentiometric titration. As a result, 8% of the charged caprolactam was converted to aminocaproic acid. Since it was not in a supercritical state, aminocaproic acid could not be synthesized in high yield even when an acidic catalyst was used.

Example 6 0.13 g of the reaction solution obtained in Example 1 and 30 g of caprolactam were charged into a glass ampule and heated at 230 ° C. for 5 hours. After the reaction, the mixture was cooled to room temperature, the ampule was cracked, and the polymer was taken out. Ηr of polymer: 2.71, [NH ₂ ] = 5.30 × 10 ⁻⁵ mo
l / g and [COOH] = 5.12 × 10 ⁻⁵ mol / g, and the degree of polymerization could be increased to a practical level in a short time.

A desired solution of caprolactam could be produced in a short time by adding a reaction solution obtained by hydrolyzing caprolactam in a supercritical state to caprolactam as it is, mixing and polymerizing.

Comparative Example 5 30 g of caprolactam and 0.12 g of water were charged into a glass ampoule and heated at 230 ° C. for 5 minutes.
Heated for hours. After the reaction, the mixture was cooled to room temperature, the ampule was cracked, and the polymer was taken out. Ηr of the polymer = 1.35,
[NH ₂ ] = 29.5 × 10 ⁻⁵ mol / g, [COOH]
= 28.9 × 10 ⁻⁵ mol / g, and the degree of polymerization was not increased to a practical level. In this case, the polymerization of caprolactam was slow because the reaction solution hydrolyzed in the supercritical state was not added.

Comparative Example 6 30 g of caprolactam, 0.12 g of water and 0.01 g of phosphoric acid were charged in a glass ampoule and heated at 230 ° C. for 5 hours. After the reaction, the mixture was cooled to room temperature, the ampule was cracked, and the polymer was taken out. Ηr of polymer: 2.01, [NH ₂ ] = 4.63 × 10 ⁻⁵ mol /
g, [COOH] = 4.58 × 10 ⁻⁵ mol / g,
The degree of polymerization did not rise to a practical level. In this case, too, the polymerization of caprolactam was slow because the reaction solution hydrolyzed in the supercritical state was not added.

Example 7 0.13 g of the reaction solution obtained in Example 1 and 30 g of laurolactam were charged into a glass ampule and heated at 230 ° C. for 5 hours. After the reaction, the mixture was cooled to room temperature, the ampule was cracked, and the polymer was taken out. Ηr of the polymer was 2.65, and it was found that the degree of polymerization increased to a practical level in a short time.

This example shows that caprolactam is hydrolyzed in a supercritical state, and the reaction solution is mixed with laurolactam and polymerized to produce a laurolactam polymer in a short time.

Reference Example The reaction solution obtained in Example 1 was concentrated under reduced pressure, and the obtained solid was purified by recrystallization from a mixed solvent of ethanol / water. 0.3 g of the obtained purified aminocaproic acid, 30 g of caprolactam and 0.12 g of water
It was charged in a glass ampoule of mL volume and heated at 230 ° C. for 5 hours. After the reaction, the mixture was cooled to room temperature, the ampule was cracked, and the polymer was taken out. Ηr of the polymer = 2.78, [N
H ₂ ] = 5.11 × 10 ⁻⁵ mol / g, [COOH] =
It was 5.04 × 10 ⁻⁵ mol / g. By adding aminocaproic acid obtained by purification, a practical level of polymerization could be achieved in a short time, but the productivity was inferior due to the purification step.

[0053]

According to the present invention, α, ω-aminocarboxylic acid can be obtained in a high yield in a short time by using the hydrolysis method in a supercritical state of the present invention. Further, by adding the obtained reaction solution to lactam and polymerizing, a lactam polymer having a high degree of polymerization can be obtained in a short time and with high yield.

Claims (4)

[Claims] 1. A method for producing an α, ω-aminocarboxylic acid, comprising hydrolyzing a lactam represented by the following formula (1) in a supercritical state. Embedded image (Wherein, R ¹ represents hydrogen or a monovalent organic group having 1 to 18 carbon atoms. R ² represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and has a substituent. May be.) 2. The method according to claim 1, wherein the lactam is ε-caprolactam, ω
The process for producing α, ω-aminocarboxylic acid according to claim 1, which is -undecalactam, ω-laurolactam or a mixture thereof. 3. A lactam represented by the following formula (1) is hydrolyzed in a supercritical state, and the obtained product is added to a lactam represented by the following formula (1) for polymerization. Lactam polymerization method. Embedded image (Wherein, R ¹ represents hydrogen or a monovalent organic group having 1 to 18 carbon atoms. R ² represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and has a substituent. May be.) 4. The method according to claim 1, wherein the lactam is ε-caprolactam, ω
4. The process for polymerizing a lactam according to claim 3, wherein the process is undecalactam, ω-laurolactam or a mixture thereof.