JP2009203422A - Continuously production method for polyamide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of reduced energy consumption, simplifying a process, allowing short time treatment, and producing continuously, efficiently and stably a polyamide of uniform quality over a long time, in the continuous production method for the polyamide. <P>SOLUTION: In this continuous production method for the polyamide, a dicarboxylic acid component and an alicyclic diamine component are continuously supplied to a polymerization reactor to be continuously polymerized into a polyamide prepolymer, and then the polyamide prepolymer is continuously supplied to a twin-shaft extruder for high polymerization. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for continuously producing a polyamide from a dicarboxylic acid component having 6 to 22 carbon atoms and an alicyclic diamine component. More specifically, the dicarboxylic acid component having 6 to 22 carbon atoms and the alicyclic diamine component are supplied to the polymerization reactor to continuously polymerize the polyamide prepolymer, and then the polyamide prepolymer is continuously polymerized with a twin screw extruder. The present invention relates to an efficient and economical continuous process for producing polyamides.

  Polyamide resins are excellent in mechanical properties, heat resistance, oil resistance, gas barrier properties, and the like, and are used in various applications such as fibers, films, automobile parts, and electrical / electronic parts. Along with the expansion of application fields, there are demands for fibers, films, and covers for various devices that have characteristics of polyamide resin and have excellent transparency and shape retention of molded products.

  Conventionally, various proposals have been made regarding a method for obtaining a transparent and amorphous (amorphous) polyamide resin by suppressing the crystallinity of the polyamide resin. For example, Patent Documents 1, 2, and 3 disclose a method of producing a polymer by melting and reacting an amorphous polyamide resin with a dicarboxylic acid and a diamine using a batch type high-pressure polymerization kettle. However, the amorphous polyamide resin has a problem that it has a high melt viscosity relative to the molecular weight and must be discharged from the polymerization kettle at a low molecular weight stage.

  In addition, several production methods have been proposed in order to obtain a high molecular weight polyamide resin by dividing it into several production steps. For example, in Patent Document 4, a low-order condensate is prepared by melt reaction of dicarboxylic acid and diamine, and this is solid-phase polymerized to prepare a polyamide precursor, and then the precursor is further melt-polymerized to produce a polyamide. A method has been proposed. However, manufacturing requires three steps, which is not preferable because the manufacturing cost increases and is not economical. Further, in the solid phase polymerization in the second step, the polymerization rate is slow and it takes time to produce, so an apparatus having a large processing capacity is required. Furthermore, in order to melt-polymerize the polyamide precursor solid-phase polymerized at a low temperature and remelt it, heat energy is disadvantageous.

  On the other hand, as a method of polymerizing in two steps, for example, in Patent Document 5, after dicarboxylic acid and diamine are mixed in equimolar amounts, a low-order polymer is obtained by uniform melt polymerization in the presence of water, and then melt-kneaded. A method for producing a polyamide copolymer by polymerization has been proposed. However, in the polymerization of a low-order polymer using a batch type polymerization kettle, it is necessary to prepare the raw material as an aqueous solution of salt or / and monomer in the polymerization kettle and prevent solidification during the polymerization by lowering the freezing point of the low-order polymer. For this reason, not only a polymerization kettle that can maintain a high polymerization pressure is required, but also extra energy for removing water in the polymerization stage is required, which is not preferable.

  As a continuous production method that does not use an aqueous solution as a raw material, for example, Patent Document 6 discloses that an essentially dry dicarboxylic acid and diamine are melted and mixed in an equimolar amount to form a molten reaction mixture, and aeration is performed. A non-reacting vessel forms a first product stream containing polyamide and polymerized water, and the polymerized water is removed through the vented vessel to produce a second product stream containing polyamide. Here, a portion of the second product stream is recycled to the aerated container. In order to obtain the polymer molecular weight of the final product as the second product stream, a method for producing polyamide has been proposed in which the second product stream is supplied to the second reactor and further polymerized. However, since part of the second product stream is recirculated, the residence time in the reactor is uneven, and the second reactor that polymerizes to the final product is inferior in self-cleaning properties. There is a problem that is easy to generate, which is not preferable.

Moreover, as a continuous manufacturing method of nylon 66, for example, in Patent Document 7, one or more of raw material monomers, an aqueous salt solution, an aqueous salt concentrate and a salt are continuously supplied to a pressure polymerization kettle and stirred under conditions of 150 to 320. A continuous production method of nylon 66 has been proposed in which a primary condensate having a relative viscosity (ηr) of 1.01 to 2.5 is continuously polymerized by heating at 0 ° C. and then continuously increased in degree of polymerization by a melting machine. However, as in the case of Patent Document 5, an aqueous solution is not preferable because it requires extra energy for removing water in the polymerization stage. Furthermore, since the polymerization temperature is as high as 320 ° C., there is a problem that the primary condensate tends to be thermally deteriorated, which is not preferable.
JP-A-8-269194 JP 2000-1544 A JP 2004-83858 A JP-A-8-311198 JP 7-138366 A JP-T-2002-516366 Japanese Patent Laid-Open No. 5-230208

  Therefore, the present invention is to solve the above-mentioned problems of the prior art in the continuous production method of polyamide, the process is simplified, the amount of energy used is reduced by short-time treatment, and a homogeneous polyamide is continuously produced over a long period of time. It is providing the method of manufacturing efficiently and stably.

As a result of intensive studies to solve the above problems, the present invention is as follows.
1. A polyamide prepolymer is continuously polymerized by continuously supplying a dicarboxylic acid component having 6 to 22 carbon atoms and an alicyclic diamine component represented by the following structural formula (1) directly to the polymerization reactor, and then the polyamide prepolymer A continuous production method of polyamide, characterized in that the degree of polymerization is increased by continuously feeding directly to a twin screw extruder.

(Here, R ¹ is a hydrocarbon represented by C _n H _2n (n = 1 to 3), R ² and R ³ may be the same or different, and H or C _n H _{2n + 1} (n = 1 to 3).
2. 2. The method for continuously producing a polyamide according to 1, wherein the polyamide prepolymer is continuously polymerized by continuous polymerization for 10 to 40 minutes under conditions of a temperature of 230 to 320 ° C. and a pressure of 0 to 4 MPa.
3. 3. The method for continuously producing a polyamide according to 1 or 2, wherein the relative viscosity (ηr) of the polyamide prepolymer continuously supplied to the twin-screw extruder is in the range of 1.2 to 2.5.
4). The temperature when continuously increasing the degree of polymerization with a twin-screw extruder is the melting point +5 to + 50 ° C. when the polyamide is crystalline, and the glass transition temperature +50 to + 200 ° C. when the polyamide is amorphous. The continuous production method of a polyamide as described in any one of 1 to 3, wherein the degree of continuous polymerization is increased while removing water generated by the process.
5. The dicarboxylic acid component having 6 to 22 carbon atoms and the alicyclic diamine component represented by the structural formula (1) are melted or slurried and continuously supplied to the polymerization reactor. The continuous manufacturing method of the polyamide in any one.
6). The alicyclic diamine component represented by the structural formula (1) is 4,4′-diaminodicyclohexylmethane or 4,4′-diamino-3,3′-dimethyldicyclohexylmethane. 6. A process for continuously producing a polyamide as described in any of 5 above.

  The method of the present invention simplifies the process, makes it possible to efficiently and stably produce a polyamide having a relatively high molecular weight, which is homogeneous and relatively high in molecular weight, for a long period of time, with a short processing time. .

Below, the continuous manufacturing method of the polyamide of this invention is demonstrated in detail.
According to the present invention, a dicarboxylic acid component and an alicyclic diamine component are continuously supplied to a polymerization reactor to continuously polymerize a polyamide prepolymer, and then the polyamide prepolymer is continuously supplied to a twin-screw extruder. It is important to increase the degree of polymerization. Here, the water contained in the dicarboxylic acid component and the alicyclic diamine component used for the raw material must be removed in the polymerization stage, and extra energy is required for that purpose.

  In the present invention, the dicarboxylic acid component and the alicyclic diamine component used in the raw material may be those that form an aromatic amide unit or an aliphatic amide unit constituting the polyamide. The thing is mentioned. Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, and terephthalic acid and isophthalic acid are preferably used.

  Aliphatic dicarboxylic acid components include adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, octadecanedioic acid There are C2-C18 aliphatic dicarboxylic acids such as acids, and dodecanedioic acid is preferably used.

  The alicyclic diamine component of the present invention is an alicyclic diamine represented by the following structural formula (1).

(Here, R ¹ is a hydrocarbon represented by C _n H _2n (n = 1 to 3), R ² and R ³ may be the same or different, and H or C _n H _{2n + 1} (n = 1 to 3))) Specific examples of the alicyclic diamine include 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane and 4,4′-diaminodicyclohexylpropane and the like can be mentioned. These may be used alone or in combination of two or more.

  In the present invention, an aliphatic aminocarboxylic acid or lactam can be further used. The aliphatic aminocarboxylic acid is a ω-aminocarboxylic acid having 4 to 12 carbon atoms, and the lactam is a cyclic amide compound (lactam having three or more members) having 4 to 12 carbon atoms. Specific examples of the aliphatic aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctylic acid, 9-aminononanoic acid, 10-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and so on. Specific examples of the lactam include ε-caprolactam, ω-enantolactam, ω-undecanactam, and ω-dodecalactam. Among these, in the present invention, 12-aminododecanoic acid and ω-dodecalactam are preferable and used.

  It is preferable that the dicarboxylic acid component and the alicyclic diamine component as raw materials and, if necessary, the aliphatic aminocarboxylic acid are in a molten state or a slurry state and directly supplied to the polymerization reactor without premixing. For this, the raw material is heated at a temperature equal to or higher than the melting point, melted and supplied in a liquid state. About the raw material which does not fuse | melt, it is preferable to supply in the state of a slurry with the melt | dissolved raw material or water. Here, when the solid raw material is melted, it is heated to a high temperature equal to or higher than the melting point. Therefore, it is preferable to remove oxygen from the raw material or the raw material tank before heating for the purpose of preventing coloring and deterioration due to oxygen. The method for removing oxygen is not particularly limited, and oxygen can be removed by a known method such as a batch-type vacuum and replacement with an inert gas such as nitrogen, or a method of blowing an inert gas such as nitrogen. That's fine. Moreover, there is no restriction | limiting in particular also about the melting method of a raw material, What is necessary is just to melt | dissolve using a melt | dissolution can, an extruder, etc., However, Selection of the material which considered the corrosion by an acid is required.

  In the present invention, the melted or slurry dicarboxylic acid component and the melted alicyclic diamine component are continuously supplied to the polymerization reactor using a pump capable of quantitative supply, and the dicarboxylic acid component and the dicarboxylic acid component in the upper part of the polymerization reactor. An alicyclic diamine component is mixed, and preferably a polyamide prepolymer can be produced by continuous polymerization for 10 to 40 minutes under conditions of a temperature of 230 to 320 ° C. and a pressure of 0 to 4 MPa. Here, the polyamide prepolymer is a composition obtained by heat treatment of a dicarboxylic acid component and an alicyclic diamine component, and refers to a mixture containing oligomers, unreacted monomers, and water produced by polycondensation.

  The reaction temperature when producing the polyamide prepolymer of the present invention is usually 230 to 320 ° C, preferably 240 to 310 ° C, more preferably 250 to 300 ° C. Since reaction time becomes long, 230 degreeC or more is preferable for reaction temperature. Further, the reaction temperature is preferably 320 ° C. or lower in order to prevent thermal decomposition and formation of a gelled product.

  The pressure at the time of producing the polyamide prepolymer of the present invention is usually operated so as to be maintained at 0 to 4 MPa, preferably 0 to 3 MPa, more preferably 0 to 2 MPa. The pressure is preferably low from the viewpoint of raw material supply accuracy and equipment cost.

  The reaction time when producing the polyamide prepolymer of the present invention is usually 10 to 40 minutes, preferably 15 to 35 minutes, more preferably 20 to 30 minutes. When the resulting polyamide prepolymer has a low viscosity, the composition ratio is shifted during polycondensation in the next step, and the viscosity is difficult to increase. Therefore, the reaction time is preferably 10 minutes or more. Moreover, in order to prevent thermal decomposition, the production | generation of a gelled material, and abnormal residence, reaction time is 40 minutes or less.

  In the present invention, the polymerization reactor is not particularly limited, but a reactor having a vertical cylindrical shape and partitioned by a perforated plate or the like is preferably used so that unnecessary convection does not occur. Moreover, well-known things, such as a static line mixer and a stirrer, can be used for the upper part in a polymerization reactor so that the supplied dicarboxylic acid component and alicyclic diamine component may be mixed easily. In addition, a rectifying tower is installed at the top of the polymerization reactor to prevent the alicyclic diamine component from flowing out so that the alicyclic diamine component flows out together with water during pressure adjustment to prevent the composition ratio from shifting. can do.

  The relative viscosity (ηr) of the polyamide prepolymer obtained here is usually from 1.2 to 2.5, preferably from 1.2 to 2.2, more preferably from 1.2 to 2.0. When the degree of polymerization is increased in the next step, the relative viscosity is preferably 1.2 or more so as to prevent a shift in the composition ratio or to easily increase the degree of polymerization. In addition, the relative viscosity is preferably 2.5 or less in order to prevent the formation of a gelled product in the polymerization reactor due to a high melt viscosity and abnormal residence. Here, the relative viscosity (ηr) is a value obtained by dissolving a sample in 98% sulfuric acid at a concentration of 0.01 g / ml according to JIS K6810 and using an Ostwald viscometer at 25 ° C.

  In the production of the polyamide prepolymer of the present invention, it is effective to add a polymerization degree modifier to facilitate the adjustment of the polymerization degree, and it is added to the polymerization reactor together with the dicarboxylic acid component or the alicyclic diamine component as the raw material. Can be supplied. As the polymerization degree modifier, an organic acid and / or an organic base is used. The organic acid is preferably benzoic acid, acetic acid, or stearic acid, and more preferably benzoic acid is used. As the organic base, an aliphatic diamine having 4 to 14 carbon atoms is used, and hexamethylene diamine is preferably used. The addition amount of the polymerization degree adjusting agent is 0 to 0.1 times mol, preferably 0.0001 to 0.05 times mol, based on the total number of moles of the dicarboxylic acid component and the alicyclic diamine component as raw materials.

  In the production of the polyamide prepolymer of the present invention, a phosphoric acid catalyst can also be used. The phosphorus-based catalyst has a catalytic function for polymerization reaction, and specifically, phosphoric acid, phosphate, hypophosphite, acidic phosphate ester, phosphate ester, and phosphite ester. Examples of hypophosphites include sodium hypophosphite, magnesium hypophosphite, potassium hypophosphite, calcium hypophosphite, vanadium hypophosphite, manganese hypophosphite, nickel hypophosphite, Examples include cobalt phosphite. Examples of acidic phosphate esters include monomethyl phosphate ester, dimethyl phosphate ester, monoethyl phosphate ester, diethyl phosphate ester, propyl phosphate ester, isopropyl phosphate ester, dipropyl phosphate ester, diisopropyl phosphate ester, butyl phosphate ester, Examples include isobutyl phosphate ester, dibutyl phosphate ester, diisobutyl phosphate ester, monophenyl phosphate ester, and diphenyl phosphate ester. Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tri-n-propyl phosphate, tri-i-propyl phosphate, tri-n-butyl phosphate, tri-i-butyl phosphate, triphenyl phosphate, Examples include tri-n-hexyl phosphoric acid, tri-n-octyl phosphoric acid, tri (2-ethylhexyl) phosphoric acid, and tridecyl phosphoric acid. Of these, hypophosphite is preferred, and sodium hypophosphite is particularly preferred. When adding a phosphorus catalyst, 0.001-5 weight part is used with respect to 100 weight part of polyamide prepolymers as the addition amount, and 0.01-1 weight part is preferable. Moreover, the addition method should just supply to a polymerization reactor with the dicarboxylic acid component or alicyclic diamine component which is a raw material, and can also add to the twin-screw extruder of the next process.

  In the present invention, in order to continuously and quantitatively discharge the polyamide prepolymer from the polymerization reactor, a discharge device such as a gear pump or a ball valve is used and continuously supplied to a directly connected twin-screw extruder. preferable.

  In the present invention, the polyamide prepolymer supplied to the twin-screw extruder has a melting point of +5 to + 50 ° C., preferably a melting point of +10 to + 40 ° C., preferably amorphous when the finally obtained polyamide is crystalline. The glass transition temperature is +50 to + 200 ° C., preferably the glass transition temperature is +80 to + 150 ° C., and is subjected to high polymerization by polycondensation to obtain polyamide. Since the polymerization reaction rate is slow and the viscosity is difficult to increase, the temperature is preferably the melting point + 5 ° C. when crystalline, and the glass transition temperature + 50 ° C. or higher when amorphous. In order to prevent thermal decomposition and the formation of a gelled product, the temperature is preferably the melting point + 50 ° C. when crystalline, and the glass transition temperature + 200 ° C. or lower when amorphous.

  Here, since the polyamide prepolymer and water are continuously supplied to the twin screw extruder at the same time, the water is continuously removed from the rear vent or the first vent installed near the supply port of the twin screw extruder, Polyamide having a high degree of polymerization can be produced by more stable polycondensation and is preferably used. In addition to the above, at least one vent port is installed and the polycondensation reaction proceeds by discharging water generated by polycondensation of the polyamide prepolymer and a very small amount of unreacted monomer out of the system. A polyamide having a high degree of polymerization is produced. The venting is preferably carried out under reduced pressure using a known decompression / vacuum device such as a Nash pump, but the pressure is not particularly limited and can be carried out under normal pressure.

  In the present invention, the residence time in the twin-screw extruder is not particularly defined, but is set so as to increase to a sufficient viscosity as a polyamide and not to cause thermal degradation or thermal decomposition due to residence for a long time, preferably 1 to 10 minutes, preferably 2 to 5 minutes.

  In the present invention, in a polyamide prepolymer production process, a polyamide production process using a twin screw extruder or a compound process, a catalyst, a heat stabilizer, a weather resistance stabilizer, an antioxidant, a plasticizer, a mold release agent, Lubricants, crystal nucleating agents, pigments, dyes, other polymers, and the like can also be added. When compounding the additive, it is more preferable to carry out simultaneously or continuously with the polycondensation in the twin-screw extruder from the viewpoint of productivity. Addition of an antioxidant is effective for improving the color tone of polyamide, and addition of sodium hypophosphite and a hindered phenol antioxidant is particularly preferable.

  The polyamide obtained by the production method of the present invention can be formed into a molded product by an ordinary molding method as in the case of conventional polyamide. There is no restriction | limiting in particular regarding a shaping | molding method, Well-known shaping | molding methods, such as injection molding, extrusion molding, blow molding, and press molding, can be utilized. The molded product referred to here includes shaped products such as fibers, films, sheets, tubes, monofilaments, etc., in addition to molded products by injection molding or the like.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, the definition of the characteristic value and the measuring method described in the claims, the specification text, the examples, and the comparative examples are as follows.

  (1) Relative viscosity (ηr): A sample was dissolved in 98% sulfuric acid at a concentration of 0.01 g / ml according to JIS K6810, and measured at 25 ° C. using an Ostwald viscometer.

  (2) Glass transition temperature (Tg), melting point (Tm): DSC (manufactured by PERKIN-ELMER) was used to measure 8 to 10 mg of sample at a heating rate of 20 ° C./min, and the inflection point of the obtained melting curve And the temperature showing the maximum value was determined from the above.

Example 1
10 kg of dodecanedioic acid (DDS) was put into a 30 L capacity can, and after nitrogen substitution, DDS was dissolved at a temperature of 170 ° C. In addition, 10 kg of 4,4′-diamino-3,3′-dimethyldicyclohexylmethane (MACM) contained in a poly container was melted in a temperature control chamber set at a room temperature of 60 ° C. and charged into a raw material tank. After the replacement, the tank was kept at 60 ° C. In addition, as a polymerization catalyst, sodium hypophosphite was mixed and added to the DDS solution so as to be 0.05 wt% with respect to 100 parts by weight of the polyamide prepolymer obtained after polymerization. The prepared raw materials were each 3 L at a feed rate of 3.45 kg / hr (14.98 mol / hr) for the DDS solution and 3.62 kg / hr (15.18 mol / hr) for the MACM solution using a plunger pump. The polymer was continuously supplied to a vertical cylindrical polymerization reactor, and the polyamide prepolymer was continuously polymerized under the conditions shown in Table 1. The polymerization reactor used was an apparatus having a rectifying column at the top of the reactor and a perforated plate inside the reactor. Sampling immediately before being supplied to a φ30 mm twin screw extruder (L / D = 42) directly connected to the polymerization reactor, the relative viscosity of the obtained polyamide prepolymer was 1.78. The continuously polymerized polyamide prepolymer was supplied from the polymerization reactor to the twin screw extruder to remove the flashed water from the rear vent, and the degree of polymerization was increased under the conditions shown in Table 1. The obtained polyamide had a relative viscosity of 2.45 and a glass transition temperature of 153 ° C., and could be produced without any problem.

Example 2
10 kg of dodecanedioic acid (DDS) was put into a 30 L capacity can, and after nitrogen substitution, DDS was dissolved at a temperature of 170 ° C. In addition, 10 kg of 4,4′-diaminodicyclohexylmethane (PACM) in a plastic container, which was melted in a temperature control room set at room temperature 60 ° C., was put into a raw material tank and replaced with nitrogen. Was kept at 60 ° C. In addition, as a polymerization catalyst, sodium hypophosphite was mixed and added to the DDS solution so as to be 0.05 wt% with respect to 100 parts by weight of the polyamide prepolymer obtained after polymerization. The prepared raw materials were each 3 L at a feed rate of 3.45 kg / hr (14.98 mol / hr) for the DDS solution and 3.19 kg / hr (15.16 mol / hr) for the PACM solution using a plunger pump. The polymer was continuously supplied to a vertical cylindrical polymerization reactor, and the polyamide prepolymer was continuously polymerized under the conditions shown in Table 1. The polymerization reactor used was an apparatus having a rectifying column at the top of the reactor and a perforated plate inside the reactor. Sampling was performed immediately before feeding to a φ30 mm twin screw extruder (L / D = 42) directly connected to the polymerization reactor, and the relative viscosity of the obtained polyamide prepolymer was 1.82. The continuously polymerized polyamide prepolymer was supplied from the polymerization reactor to the twin screw extruder to remove the flashed water from the rear vent, and the degree of polymerization was increased under the conditions shown in Table 1. The obtained polyamide had a relative viscosity of 2.51 and a melting point of 250 ° C., and could be produced without any problem.

Example 3
2.49 kg of isophthalic acid (IPA), 6.46 kg of 12-aminododecanoic acid (ADA) and 8.95 kg of ion-exchanged water were put into a 30 L slurry can, purged with nitrogen, and then slurryed at a temperature of 80 ° C. Internal stirring was started with a stirrer installed in the can to prepare a uniform dicarboxylic acid slurry. In addition, 10 kg of 4,4′-diamino-3,3′-dimethyldicyclohexylmethane (MACM) in a plastic container, which was melted in a temperature control room set at a room temperature of 60 ° C., was put into a raw material tank, and nitrogen was added. After the replacement, the tank was kept warm at 60 ° C. As a polymerization catalyst, sodium hypophosphite was mixed and added to the dicarboxylic acid slurry so as to be 0.05 wt% with respect to 100 parts by weight of the polyamide prepolymer obtained after polymerization. The prepared raw materials were each using a plunger pump, the dicarboxylic acid slurry was 8.34 kg / hr (IPA: 6.98 mol / hr, ADA: 13.98 mol / hr), and the MACM solution was 1.67 kg / hr (7. 00 mol / hr) was continuously supplied to a 3 L vertical cylindrical polymerization reactor, and the polyamide prepolymer was continuously polymerized under the conditions shown in Table 1. Next, the degree of polymerization was increased by the twin-screw extruder under the conditions shown in Table 1. The obtained polyamide had a relative viscosity of 2.38 and a glass transition temperature of 158 ° C., and could be produced without any problem.

Example 4
Dodecanedioic acid (DDS) (5.76 kg) and terephthalic acid (TPA) (4.15 kg) were charged into a 20 L-capacity dissolution vessel, and after nitrogen substitution, DDS was dissolved at a temperature of 170 ° C. After the DDS was dissolved, stirring inside was started with a stirrer installed in a dissolving can to prepare a uniform dicarboxylic acid slurry. In addition, 10 kg of 4,4′-diamino-3,3′-dimethyldicyclohexylmethane (MACM) contained in a poly container was melted in a temperature control chamber set at a room temperature of 60 ° C. and charged into a raw material tank. After the replacement, the tank was kept at 60 ° C. As a polymerization catalyst, sodium hypophosphite was mixed and added to the dicarboxylic acid slurry so as to be 0.05 wt% with respect to 100 parts by weight of the polyamide prepolymer obtained after polymerization. Each prepared raw material was supplied with a dicarboxylic acid slurry of 2.97 kg / hr (DDS and TPA of 7.49 mol / hr) and MACM solution of 3.62 kg / hr (15.18 mol / hr) using a plunger pump. The polyamide prepolymer was continuously polymerized under the conditions shown in Table 1 by continuously feeding it into a 3 L vertical cylindrical polymerization reactor at a speed. Next, the degree of polymerization was increased by the twin-screw extruder under the conditions shown in Table 1. The obtained polyamide had a relative viscosity of 2.27 and a glass transition temperature of 211 ° C., and could be produced without any problem.

Comparative Example 1
In a 3 l pressure vessel equipped with a stirrer, a thermometer, a pressure gauge, a nitrogen inlet, a pressure outlet and a polymer outlet, 460 g (2 mol) of dodecanedioic acid (DDS), 4,4′-diamino-3, 477 g (2 mol) of 3′-dimethyldicyclohexylmethane (MACM), 0.4 g of sodium hypophosphite (0.05 wt% based on 100 parts by weight of the polyamide prepolymer) and 600 g of ion-exchanged water were charged. Next, after the inside of the pressure vessel was sufficiently substituted with nitrogen, the temperature was raised in a sealed state with stirring, and the temperature in the pressure vessel was raised to 280 ° C. over 120 minutes while maintaining the pressure at 1.8 MPaG. Thereafter, the pressure in the pressure vessel was gradually released over 60 minutes to normal pressure, and then reduced pressure polymerization was performed at 300 ° C. and −160 mmHg for 30 minutes. Thereafter, the stirring was stopped, and the polyamide resin produced while pressurizing the inside of the pressure vessel with nitrogen was taken out from the polymer discharge port at the bottom of the pressure vessel in a gut shape. The obtained polyamide had a relative viscosity of 1.98 and a glass transition temperature of 154 ° C.

Comparative Example 2
In a 3 l pressure vessel equipped with a stirrer, a thermometer, a pressure gauge, a nitrogen inlet, a pressure outlet and a polymer outlet, 460 g (2 mol) of dodecanedioic acid (DDS), 4,4′-diamino-3, 477 g (2 mol) of 3′-dimethyldicyclohexylmethane (MACM), 0.4 g of sodium hypophosphite (0.05 wt% based on 100 parts by weight of the polyamide prepolymer) and 600 g of ion-exchanged water were charged. Next, after the inside of the pressure vessel was sufficiently substituted with nitrogen, the temperature was raised in a sealed state with stirring, and the temperature in the pressure vessel was raised to 280 ° C. over 120 minutes while maintaining the pressure at 1.8 MPaG. Thereafter, the pressure in the pressure vessel was gradually released over 60 minutes to normal pressure, and then reduced pressure polymerization was performed at 300 ° C. and −160 mmHg for 120 minutes. After that, the stirring was stopped, and the polyamide resin produced while pressurizing the inside of the pressure vessel with nitrogen was taken out from the polymer discharge port at the bottom of the pressure vessel in a gut-like shape, so that the melt viscosity was high and remained as a residual polymer in the pressure vessel. The yield was less than half that of Comparative Example 1. The relative viscosity of the obtained polyamide was 2.48, and the glass transition temperature was 153 ° C.

Comparative Example 3
Next, the degree of polymerization of the polyamide obtained in Comparative Example 1 was increased by the twin screw extruder under the same conditions as in Example 1. However, the obtained polyamide had a relative viscosity of 2.23 and a glass transition temperature of 153 ° C., and the viscosity could not be increased so much.

Comparative Example 4
The degree of polymerization of the polyamide prepolymer polymerized in the same manner as in Example 1 was increased not by a twin-screw extruder but by a thin film evaporator equipped with rotating blades. Although normal operation was possible at the beginning of operation, gelled material was generated after about 1 day. As a result of disassembling inspection of the thin film evaporator, polymer adhered to the shaft part of the rotor blade, and there was no self-cleaning property, so gelation was generated due to thermal degradation, and it could not be continuously operated. .

  Tables 1 and 2 show the production conditions of Examples 1 to 4 and Comparative Examples 1 to 4 and the properties of the obtained polyamide.

  As is apparent from Tables 1 and 2, in the methods of the examples, a polyamide having a relatively high molecular weight (high relative viscosity) that stably exhibits a desired viscosity and a glass transition temperature (melting point) can be efficiently obtained. No gelled product was observed.

According to the method of the present invention, the process is simplified in the continuous polyamide production method, the amount of energy used is reduced by short-time treatment, and a homogeneous and relatively high molecular weight polyamide is continuously produced for a long period of time, efficiently and stably. can do.

Claims (6)

A polyamide prepolymer is continuously polymerized by continuously supplying a dicarboxylic acid component having 6 to 22 carbon atoms and an alicyclic diamine component represented by the following structural formula (1) directly to the polymerization reactor, and then the polyamide prepolymer. A continuous production method of polyamide characterized in that it is continuously fed directly to a twin screw extruder to increase the degree of polymerization.

(Where R ¹ is a hydrocarbon represented by C _n H _2n (n = 1 to 3), R ² and R ³ may be the same or different, and H or C _n H _{2n + 1} (n = 1 to 3). The method for continuously producing a polyamide according to claim 1, wherein the polyamide prepolymer is continuously polymerized by continuous polymerization for 10 to 40 minutes under conditions of a temperature of 230 to 320 ° C and a pressure of 0 to 4 MPa. The method for continuously producing a polyamide according to claim 1 or 2, wherein the polyamide prepolymer continuously supplied to the twin-screw extruder has a relative viscosity (ηr) in the range of 1.2 to 2.5. The temperature when continuously increasing the degree of polymerization with a twin-screw extruder is the melting point +5 to + 50 ° C. when the polyamide is crystalline, and the glass transition temperature +50 to + 200 ° C. when the polyamide is amorphous. The continuous production method of a polyamide according to any one of claims 1 to 3, wherein the degree of continuous polymerization is increased while removing water generated by the process. The dicarboxylic acid component having 6 to 22 carbon atoms and the alicyclic diamine component represented by the structural formula (1) are in a molten state or a slurry state, and are continuously supplied to the polymerization reactor. 4. The continuous production method of a polyamide as described in any one of 4 above. The alicyclic diamine component represented by the structural formula (1) is 4,4'-diaminodicyclohexylmethane or 4,4'-diamino-3,3'-dimethyldicyclohexylmethane. The continuous manufacturing method of the polyamide in any one of 1-5.