JP2009286896A - Apparatus for producing polyamide resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable batch type apparatus for production without blocking trouble in a batch type method for producing a polyamide resin by which a diamine is added to a dicarboxylic acid in a molten state and direct polycondensation is carried out by using a batch type reaction vessel having a dephlegmator. <P>SOLUTION: The apparatus for producing the polyamide resin is designed to continuously or intermittently add the diamine to the dicarboxylic acid in the molten state, and carry out the direct polycondensation of the diamine with the dicarboxylic acid. The apparatus for producing the polyamide resin is characterized by providing the batch type reaction vessel, the dephlegmator, and a pipe connecting the reaction vessel to the dephlegmator, and providing a function to lead a vapor consisting essentially of condensation water produced by the polycondensation reaction from the reaction vessel to the dephlegmator and a function to return a reflux condensed in the dephlegmator to the reaction vessel in combination. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyamide resin production apparatus.

  A general polyamide production method uses nylon salt or an aqueous solution thereof as a feedstock, and in a batch system, the aqueous nylon salt solution is heated under pressure in a single reaction tank, and polymerization is carried out in a uniform phase while suppressing the distillation of diamine. Then, after fixing the diamine, the water vapor in the system is gradually released, and finally the pressure is reduced to normal pressure or reduced pressure to complete the polymerization. At this time, it is common to use an aqueous solution of about 50% by weight nylon salt as a feedstock, but a high pressure resistance specification is required in order to prevent the distillation of water as a solvent in the initial stage of polymerization. A large amount of water and condensed water must be removed. At this time, polyamide adheres to the reaction vessel wall surface due to foaming, solidification of the polymer due to the latent heat of vaporization of water, and large liquid level fluctuation during the reaction, resulting in thermal degradation. It is necessary to take measures to avoid various inconveniences. In addition, a large amount of water is required to remove a large amount of water, and there are many technical and economic problems such as a low yield of polyamide obtained by one reaction. On the other hand, when nylon salt is used as a feedstock (Patent Document 1 and Patent Document 2), these disadvantages are considerably solved, but it is necessary to isolate and purify the nylon salt, which is an efficient method. hard.

  As a polymerization method in which nylon salt and an aqueous solution of nylon salt are not used as a feedstock, a reaction is carried out by dropping a diamine containing a small amount of water into a dicarboxylic acid in a molten state at a temperature of 220 ° C. or lower under normal pressure (Patent Document 3) There is also a method (Patent Document 4, Patent Document 5, etc.) in which a diamine is dropped into a dicarboxylic acid in a molten state under normal pressure to cause a direct reaction.

  These methods are technically and economically advantageous. However, as a problem with adding a diamine directly to a dicarboxylic acid in a molten state, the dicarboxylic acid in a molten state has sublimation property, and polymerization Dicarboxylic acid sublimate adheres to the ceiling of the apparatus. Further, the sublimate of dicarboxylic acid adheres to the inner walls of various pipes connected to the upper part of the polymerization apparatus, for example, the inlet of the additive, the inlet of the diamine, the inner wall of the steam pipe, and the inside of the condenser. Most of the attached sublimates of dicarboxylic acid are dissolved and washed by the vapor of condensed water generated in the reaction during the polymerization reaction. The dicarboxylic acid sublimate is generated not only when the molten dicarboxylic acid is present alone in the polymerization apparatus, but also during the diamine addition step in which the dicarboxylic acid is not sufficiently fixed. For this reason, since the sublimate of dicarboxylic acid entrained by the vapor of the condensed water generated by the polymerization reaction is attached to the steam pipe and the partial condenser, most of the sublimate of dicarboxylic acid adheres in the part of the polymerization apparatus. . Moreover, it reacts with the entrained diamine to produce a nylon salt or oligomer, which does not dissolve in condensed water, adheres and accumulates every time the number of batches is increased, and receives a thermal history.

For the deposition on the steam pipe and the partial condenser, the internal temperature of the steam pipe, which is mainly composed of condensed water generated by the polycondensation reaction, leads the steam generated in the reaction tank from the reaction tank to the partial condenser, and A method in which the internal temperature of the partial condenser is controlled to condense a part of the water vapor, and the dicarboxylic acid adhering to the sublimation and / or the adhering nylon salt or oligomer is washed away and circulated in the reaction tank together with the condensed water (Patent Document 6) There is. This method was effective in washing out the deposits in the steam pipe and the partial condenser, but the reflux pipe was filled with condensed water, so it was thinner than the vapor pipe and washed out the deposits in the partial condenser. At this time, undissolved deposits adhere and deposit on the reflux pipe. Nylon salts, oligomers or solutions thereof having a different molar balance between these desired diamines and dicarboxylic acids are retained in the reflux tube, thereby creating a difference between the molar ratio in the reaction tank and the desired molar ratio. . Further, by continuing the deposition, the reflux pipe is blocked, and continuous batch production cannot be performed. In addition, if these solids accumulated in the reflux pipe are lost during the reaction and mixed into the polyamide, there is a risk of causing appearance defects such as fish eyes and gels when formed into final products such as films, bottles and monofilaments. .
Japanese Patent Publication No.33-15700 Japanese Patent Publication No.43-22874 Japanese Patent Laid-Open No. 48-12390 JP 57-200420 A JP 58-1111829 A Japanese Patent Laid-Open No. 2002-60486

  An object of the present invention is to provide a polyamide resin batch production method in which a diamine is added to a dicarboxylic acid in a molten state using a batch reactor equipped with a partial condenser, and then directly polycondensed. It is in providing a batch type manufacturing apparatus.

  As a result of intensive studies to solve such problems, the present inventors have installed a pipe that shares a steam pipe and a reflux pipe, and distributes the steam and the condensate through the same pipe so that a nylon salt is formed on the pipe wall. / While preventing oligomer accumulation, blockage of piping due to nylon salt / oligomer accumulated in the pressure reducer can be prevented, eliminating troubles between the pressure reducer and the reaction tank, and mixing in solid matter. And the present invention has been completed by finding that it enables stable and continuous batch production of polyamide resin.

  That is, the present invention is an apparatus for producing a polyamide resin by continuously or intermittently adding a diamine to a dicarboxylic acid in a molten state and directly polycondensing the diamine and the dicarboxylic acid. A reactor and a decondensing unit that has both the function of introducing steam mainly composed of condensed water generated by the polycondensation reaction from the reaction tank to the deconcentrator and the function of returning the reflux liquid condensed in the decondenser to the reaction tank. It is invention regarding the manufacturing apparatus of the polyamide resin characterized by having piping which connects a container.

The following effects can be obtained by the method for producing a polyamide resin according to the present invention.
(B) The trouble of blockage of the piping connecting the reaction tank and the partial reducer is solved, and stable continuous batch production becomes possible.
(B) A high-quality polyamide resin that does not have a single reflux tube and solid matter does not accumulate, eliminates the mixing of solid matter into the reaction system, and provides molded products with little appearance defects such as fish eyes and gels. Is obtained.
(C) Since there is no single reflux pipe and no solid matter is deposited, the charged molar ratio is accurately reproduced, and a high molar ratio control becomes possible.

  Examples of the diamine used in the present invention include xylylenediamine, bis (aminomethyl) cyclohexane, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, and paraphenylenediamine. Examples of xylylenediamine include meta, para, and orthoxylylenediamine, and examples of bis (aminomethyl) cyclohexane include 1,2-, 1,3-, 1,4-bis (aminomethyl) cyclohexane. These diamines can be used alone or in combination of two or more. Here, the diamine is preferably a diamine containing xylylenediamine and / or bis (aminomethyl) cyclohexane, and 80 mol% or more of the diamine is preferably xylylenediamine and / or bis (aminomethyl) cyclohexane. . Moreover, it is preferable that 50 mol% or more of xylylenediamine and / or bis (aminomethyl) cyclohexane is metaxylylenediamine and / or 1,3-bis (aminomethyl) cyclohexane, more preferably 70 mol% or more. It is.

  Examples of the dicarboxylic acid include adipic acid, succinic acid, sebacic acid, dodecanedioic acid, isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid. These dicarboxylic acids can be used alone or in combination of two or more. Considering the practical properties of the resulting polyamide, it is particularly preferred that 50 mol% or more of the dicarboxylic acid is adipic acid. Examples of polyamide constituents other than diamines and dicarboxylic acids include lactams such as caprolactam, valerolactam, laurolactam, and undecalactam, and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. , Together with the dicarboxylic acid or with the added diamine.

  In the present invention, in order to obtain a polyamide resin having a desired molar balance (excess of diamine, excess of dicarboxylic acid and equimolar), the molar balance of charging is arbitrarily selected. The method of adjusting the molar balance of charging is, for example, measuring the dicarboxylic acid in a molten state with a mass meter with a mass meter and supplying it to the reaction vessel, then measuring the diamine storage tank with the mass meter, and adding the diamine to the reaction system. The method of supplying can be illustrated. In the present invention, when measuring the mass of diamine and dicarboxylic acid, a mass measuring instrument such as a load cell or a balance can be suitably used.

  The melting step of the dicarboxylic acid is desirably performed in an inert gas atmosphere such as nitrogen for the purpose of avoiding oxidative coloring. Although melting of the dicarboxylic acid can be carried out in a reaction tank or a dedicated melting tank, it is desirable to use a dedicated melting tank for the purpose of increasing the utilization efficiency of the reaction tank.

  When adding a diamine to a dicarboxylic acid in a molten state, it is desirable that the molten dicarboxylic acid be heated to a temperature of 160 ° C. or higher, which is a temperature at which the amidation reaction substantially proceeds, and an oligomer produced as an intermediate It is desirable that the temperature be set to a temperature at which the low molecular weight polyamide is in a molten state and the entire reaction system can maintain a uniform fluid state. Specifically, the diamine is added by stirring the dicarboxylic acid in a molten state in the reaction vessel, continuously or intermittently adding the diamine, and gradually increasing the temperature of the reaction mixture during the addition. By maintaining the temperature at Since the rate of temperature rise depends on the heat of amidation reaction, the latent heat of vaporization of condensed water, the heat of supply, etc., the diamine addition rate is adjusted as appropriate, and the temperature of the reaction mixture at the end of the addition is equal to or higher than the melting point of the polyamide (melting point + 35 ° C. ), Preferably (melting point + 5 ° C.) or more, (melting point + 25 ° C.), more preferably (melting point + 10 ° C.) or more, and (melting point + 15 ° C.).

  The pressure during the addition of the diamine is preferably normal pressure in order to efficiently distill out the generated condensed water out of the system and proceed with the polycondensation reaction, but under conditions pressurized with an inert gas or water vapor. It is also possible to do this. In that case, considering the removal efficiency of the condensed water, the pressure is selected from 0.9 MPaG or less, preferably 0.7 MPaG or less, more preferably 0.5 MPaG or less.

In the direct polymerization method of the present invention, as in the case of the pressurization method using a known nylon salt aqueous solution as a raw material, it is difficult to distill diamine out of the reaction system, and the reaction vessel is equipped with a partial condenser. It is necessary. Further, a sublimate of dicarboxylic acid is generated from the reaction tank before the addition of diamine and in the initial stage of addition. By providing the partial condenser, it is possible to effectively prevent the diamine and dicarboxylic acid from being distilled out of the system. The condensed water produced as the reaction proceeds is separated from the diamine distilled from the reaction tank together with the condensed water and the dicarboxylic acid distilled by sublimation, and condensed in the total condenser and removed from the reaction system. The diamine is condensed in a partial condenser, and the dicarboxylic acid is washed away by the condensed diamine and returned to the reaction vessel.
It is preferable that the internal temperature of the partial condenser (temperature on the inner surface of the vapor side) is 160 ° C. or lower, and is controlled to the saturated water vapor temperature −10 ° C. to the saturated water vapor temperature + 10 ° C. of the internal pressure of the partial condenser. Preferably it is 150 degrees C or less, Comprising: It is this saturated water vapor temperature-5 degree C-this saturated water vapor temperature.

The present invention relates to a function of a steam pipe, that is, a function of guiding steam mainly composed of condensed water generated by a polycondensation reaction from a reaction tank to a partial condenser, and a function of a reflux pipe, that is, a reflux liquid condensed in the partial condenser. It is characterized by having a pipe (hereinafter referred to as “common pipe”) for connecting the reaction tank and the partial condenser, which has a function of returning the water to the reaction tank.
It is preferable that the common pipe has a sufficient pipe diameter corresponding to the amount of steam so that the steam linear velocity is 0.2 to 10 m / sec. By flowing the reflux liquid through the common pipe, it is possible to prevent clogging with the nylon salt / oligomer deposited on the partial condenser while preventing the nylon salt / oligomer from depositing on the inner surface of the common pipe. The common pipe inner surface preferably has a 10-point average roughness specified in JIS B 0601 of 12.5 μm or less, and more preferably 6.3 μm or less. Further, the ten-point average roughness of the inner surface of the reaction tank near the opening on the side of the condenser is preferably 12.5 μm or less, and more preferably 6.3 μm or less.

  In the upper part of the common pipe, that is, near the opening on the side of the partial condenser, in order to efficiently guide the reflux liquid condensed by the partial condenser to the inner surface of the common pipe, a dispersion device, for example, from the central part to the outer peripheral edge. A Jinkasa-shaped dispersion plate or the like that is inclined obliquely downward may be installed, and the dispersion device may be mounted in a partial condenser. Further, the surface preferably has a 10-point average roughness specified in JIS B 0601 of 12.5 μm or less, and more preferably 6.3 μm or less.

  A temperature adjusting means may be provided on the outer periphery of the common pipe. For example, when using metaxylylenediamine as the diamine and adipic acid as the dicarboxylic acid, the inner surface temperature of the shared pipe is a temperature of 160 ° C. or less, preferably (saturated steam temperature −60 at the pressure inside the shared pipe) C.) to (the saturated water vapor temperature + 30 ° C.) or less, more preferably (the saturated water vapor temperature−10 ° C.) or more and (the saturated water vapor temperature + 10 ° C.) or less. If the inner surface temperature of the common pipe is too high, nylon salts will precipitate due to the evaporation of water in the reflux liquid, or a solid material generated by the thermal history and amidation reaction proceeds to become an oligomer and the solubility rapidly decreases. Causes accumulation. In addition, when the inner surface temperature of the common pipe is too low, condensation of the condensed water generated by the polymerization reaction becomes remarkable, it becomes a reflux state inside the common pipe, and it is difficult to efficiently discharge the condensed water out of the reaction system. Become.

  The dicarboxylic acid sublimate is generated not only when the dicarboxylic acid is present alone in the reaction vessel in a molten state, but also during the diamine addition step, especially in the initial stage of addition when the dicarboxylic acid is not sufficiently fixed. Occurrence is observed. By controlling the internal temperature of the partial condenser, the dicarboxylic acid adhering to the sublimation and / or the adhering nylon salt or oligomer can be washed away and circulated with the condensed water in the reaction vessel. In the present invention, in order to quickly return the deposit in the above-described partial condenser to the reaction tank, the common pipe is inclined downward from the partial condenser toward the reaction tank, and has a structure without a horizontal portion. desirable. If there is a horizontal portion, even if condensation water is sufficiently condensed, the deposits in the partial condenser cannot be completely returned to the reaction vessel. For this reason, it reacts with the diamine accompanying the condensed water to produce a nylon salt. When the solubility of the nylon salt in water is low, the nylon salt is not dissolved, and the amidation reaction proceeds to become an oligomer every time the number of batches is repeated, and further the solubility in water decreases. As a result, solid matter accumulates in the shared pipe, and eventually the shared pipe is blocked.

  Hereinafter, the present invention will be specifically described with reference to examples and comparative examples. However, the present invention is not limited to these examples and comparative examples. Each analysis method is as follows.

(1) Amino end group concentration 0.3-0.5 g of polyamide resin was precisely weighed and dissolved in 30 ml of a phenol / ethanol mixed solution (mixing volume ratio 4: 1) with stirring at room temperature. After complete dissolution, it was determined by neutralization titration with 0.01 mol / l aqueous hydrochloric acid while stirring.
(2) Carboxyl end group concentration 0.3-0.5 g of polyamide resin was precisely weighed and dissolved in 30 ml of benzyl alcohol with stirring at 160-180 ° C. in a nitrogen stream. After complete dissolution, the mixture was cooled to 80 ° C. under a nitrogen stream, 10 ml of methanol was added with stirring, and neutralization titration with a 0.01 mol / l sodium hydroxide aqueous solution was performed.
(3) Number average molecular weight It calculated | required by following Formula from the titration quantitative value of the amino terminal group and the carboxyl terminal group.
Number average molecular weight = 2 / ([NH ₂ ] + [COOH])
However, [NH ₂ ] represents the amino end group concentration, [COOH] represents the carboxyl end group concentration, and the unit is mol / g.

<Example 1>
A double pipe structure with an outer cylinder having a nominal diameter of 125A and an inner cylinder having a nominal diameter of 40A, a common pipe without a horizontal portion through which temperature-adjusted oil flows, and a contractor through which temperature-adjusted oil flows 15 kg of adipic acid (purity: 99.85% by mass, water content: 0.15% by mass) in a 50 liter stainless steel reactor equipped with a total condenser, stirrer, nitrogen gas inlet tube and diamine dropping port Was added, and the temperature was raised to 190 ° C. with stirring while flowing a 250 ° C. heating medium through the jacket while flowing a small amount of nitrogen. Next, 13.902 kg of metaxylylenediamine (purity: 99.93% by mass) was continuously added dropwise under atmospheric pressure over 2 hours while flowing a 300 ° C. heating medium through the jacket and stirring the molten adipic acid. The charged molar ratio (diamine / dicarboxylic acid) is 0.9953. During this time, the internal temperature was continuously raised to 250 ° C. Water distilled with the addition of metaxylylenediamine was removed out of the reaction system through a partial condenser and a full condenser.

  The temperature-adjusted oil was supplied to the common pipe and the partial condenser, and the internal temperature of the common pipe was controlled to 100 ° C to 140 ° C, and the internal temperature of the partial condenser was controlled to 100 to 104 ° C. After completion of the dropwise addition of metaxylylenediamine, the temperature was raised to 260 ° C. with stirring under normal pressure and held for 30 minutes. Thereafter, the pressure was reduced to 80 kPa-abs over 5 minutes, and the pressure was maintained at 80 kPa-abs for 20 minutes. Thereafter, the pressure was changed to normal pressure, and the polyamide resin was taken out from the nozzle at the bottom of the reaction vessel and solidified with water. When the reaction vessel was cooled to 100 ° C. or lower, the next reaction by the same operation was started. In this manner, a total of 10 batch reactions were repeated continuously, and the terminal group concentration of the obtained polyamide resin was quantified. As a result, the molar ratio of the polyamide resin in each batch was 0.994 to 0.995, and the number average molecular weight was stable at 15,000 to 15,500. Similarly, after reacting continuously for 30 batches, the inside of the common pipe was observed, and no solid matter was found in the pipe.

<Example 2>
A double pipe structure with an outer cylinder having a nominal diameter of 125A and an inner cylinder having a nominal diameter of 40A, a common pipe without a horizontal portion through which temperature-adjusted oil flows, and a contractor through which temperature-adjusted oil flows Adipic acid (purity: 99.85% by mass, moisture: 0) in a 50 liter stainless steel reaction vessel (withstand pressure 1.0 MPaG) equipped with a total condenser, stirrer, nitrogen gas inlet tube and diamine dropping port .15 mass%) 15 kg was charged, and the atmosphere was replaced with nitrogen. After pressurizing to 0.4 MPaG with nitrogen, a heating medium of 250 ° C. was passed through the jacket, and the temperature was raised to 190 ° C. while stirring. Then, a heating medium at 300 ° C. was passed through the jacket, and 15.902 kg of metaxylylenediamine (purity: 99.93% by mass) was continuously stirred for 2 hours under a pressure of 0.4 MPaG while stirring the molten adipic acid. It was dripped. The charged molar ratio (diamine / dicarboxylic acid) is 0.9953. During this time, the internal temperature was continuously raised to 250 ° C. Water distilled with the addition of metaxylylenediamine was removed out of the reaction system through a partial condenser and a full condenser.

  The temperature-controlled oil was allowed to flow through the common pipe and the partial condenser, and the internal temperature of the common pipe was controlled at 130 to 170 ° C., and the internal temperature of the partial condenser was controlled at 140 to 150 ° C. After completion of the dropwise addition of metaxylylenediamine, the temperature was raised to 260 ° C. while stirring at a pressure of 0.4 MPaG and held for 5 minutes. Thereafter, the pressure was reduced to 80 kPa-abs over 50 minutes, and the pressure was maintained at 80 kPa-abs for 20 minutes. Thereafter, the pressure was changed to normal pressure, and the polyamide resin was taken out from the nozzle at the bottom of the reaction vessel and solidified with water. When the reaction vessel was cooled to 100 ° C. or lower, the next reaction by the same operation was started. The reaction was repeated continuously for a total of 10 batches in this manner, and the terminal group concentration of the obtained polyamide resin was quantified. As a result, the molar ratio of the polyamide resin in each batch was 0.994 to 0.995, and the number average molecular weight was stable at 15,500 to 16,000. Similarly, after the reaction was continuously carried out for 30 batches, the situation inside the common pipe was observed, and no solid matter was observed.

<Comparative Example 1>
Instead of the common pipe, a double pipe structure having an outer cylinder having a nominal diameter of 125A and an inner cylinder having a nominal diameter of 40A, a steam pipe through which temperature-controlled oil flows and a reflux pipe having a nominal diameter of 20A are used. The reaction was conducted in the same manner as in Example 1 except that. The 30th batch had a molar ratio of 0.984 and a number average molecular weight of 10,000. When the inside of the reflux pipe was observed, solid matter in the piping was adhered, the piping was blocked by solid matter, and a pool of condensate containing unreacted metaxylenediamine was seen upstream. It was. When the solid substance collected from the inside of the reflux tube was dissolved with hot water at 90 ° C., 15 to 35% by mass was insoluble. This solid substance is considered to be a mixture of adipic acid, nylon salt and oligomer, and it is considered that a part of the polymerization progressed and it became insoluble in hot water.

<Comparative Example 2>
Instead of the common pipe, a double pipe structure having an outer cylinder having a nominal diameter of 125A and an inner cylinder having a nominal diameter of 40A, a steam pipe through which temperature-controlled oil flows and a reflux pipe having a nominal diameter of 20A are used. The reaction was conducted in the same manner as in Example 2 except that. When the reaction was carried out continuously for 30 batches, no accumulation of condensate containing unreacted metaxylenediamine was observed in the upstream part of the reflux pipe, but solid matter in the reflux pipe was deposited, and the pipe was solid. As a result, 2/3 of the cross-sectional area of the reflux pipe was blocked.

  The production apparatus for polyamide resin of the present invention is suitably used as a stable batch production apparatus without clogging.

Claims (11)

An apparatus for producing a polyamide resin by continuously or intermittently adding a diamine to a dicarboxylic acid in a molten state and directly polycondensing the diamine and the dicarboxylic acid, and comprising a batch reactor, a partial condenser, and a polycondensation Piping that connects the reaction tank and the partial condenser, which has both the function of guiding the steam, mainly condensed water generated by the reaction, from the reaction tank to the condenser and the function of returning the reflux liquid condensed in the partial condenser to the reaction tank. An apparatus for producing a polyamide resin, comprising: The apparatus for producing a polyamide resin according to claim 1, wherein a dispersion device for guiding the reflux liquid condensed in the partial condenser is provided in the vicinity of the opening on the partial condenser side of the pipe. The apparatus for producing a polyamide resin according to claim 2, wherein the ten-point average roughness defined in JIS B 0601 on the surface of the dispersing device is 12.5 µm or less. The apparatus for producing a polyamide resin according to claim 1, wherein the ten-point average roughness defined in JIS B 0601 of the inner surface of the pipe is 12.5 µm or less. 2. The polyamide resin production apparatus according to claim 1, wherein the ten-point average roughness defined in JIS B 0601 is 12.5 μm or less on the inner surface of the reaction tank in the vicinity of the opening on the side of the condenser. The apparatus for producing a polyamide resin according to claim 1, wherein a temperature adjusting means is provided on an outer peripheral portion of the pipe. The apparatus for producing a polyamide resin according to claim 6, wherein the temperature adjusting means can adjust the surface temperature in the pipe to a temperature of a saturated water vapor temperature of -60 ° C or higher and a saturated water vapor temperature of + 30 ° C or lower at a pressure inside the pipe. . The apparatus for producing a polyamide resin according to claim 1, wherein the diamine contains xylylenediamine and / or bis (aminomethyl) cyclohexane. The apparatus for producing a polyamide resin according to claim 1, wherein 80 mol% or more of the diamine is xylylenediamine and / or bis (aminomethyl) cyclohexane. The apparatus for producing a polyamide resin according to claim 9, wherein 50 mol% or more of xylylenediamine and / or bis (aminomethyl) cyclohexane is metaxylylenediamine and / or 1,3-bis (aminomethyl) cyclohexane. The apparatus for producing a polyamide resin according to claim 1, wherein 50 mol% or more of the dicarboxylic acid is adipic acid.