KR101938615B1 - Method for preparing polyamide resin - Google Patents

Abstract

Disclosed is a novel method for preparing a linear aliphatic polyamide resin, wherein in preparing a linear aliphatic polyamide resin containing cadaverine, the amount of cyclic byproducts generated during polymerization and the discoloration occurring under high temperature and high pressure is reduced, and the use of a flash process is not required. Provided is the method for preparing a linear aliphatic polyamide resin, which comprises the following steps: (a) adding a dicarboxylic acid, a diamine and a solvent to a first reactor and preliminarily polymerizing to prepare a prepolymer; (b) discharging and solidifying the preliminarily polymerized prepolymer while maintaining the temperature of the preliminarily polymerized prepolymer higher than the melting point of the prepolymerized prepolymer; and (c) introducing the solidified prepolymer into a second reactor and performing solid phase polymerization at the temperature of less than 200°C.

Description

[0001] METHOD FOR PREPARING POLYAMIDE RESIN [0002]

The present invention relates to a method for producing a polyamide resin, and more particularly, to a method for producing a linear aliphatic polyamide resin by an economical method.

Polyamide (PA) is one of the engineering plastics widely used in automobiles, electric and electronic parts, etc., and has different physical properties depending on the number of carbon atoms of constituent components, and is used in various fields depending on properties suitable for industrial use.

These polyamides are produced mainly through ring-opening reaction and condensation reaction. PAAM, PA610, PA612, and PA6T, which are polyamide resins prepared through the condensation reaction, are amide monomers mainly composed of hexamethylene diamine ; HMDA) have been used.

Examples of diamine monomers other than HMDA include 1,4-butanediamine, 1,10-decanediamine, 1,12-dodecanediamine, and the like. Monomers having an even number of carbons were mainly used. This is due to the economical problem of using a petrochemical-based diamine having an odd number of carbons as a monomer of a polymer.

However, as the technology capable of biologically producing monomers developed, various diamine monomers began to be produced, and an odd number of carbon-bearing cadaverine (CAD) appeared. Cadaverine has five carbons, biologically producible through de-carbonation of lysine produced from biomass, and economically applicable as a polymeric monomer.

Non-Patent Document 1 (Dyetec vision 139, 2016, p12-15) shows that PA56 incorporating bio-derived cadaverine having an odd number of carbons is excellent in dyeability and water absorbency compared to PA66, The lack of one carbon number relative to hexamethylenediamine indicates that all the NHs are not fully involved in the hydrogen bonding, leaving room for the acceptance of dye and moisture. However, this document does not describe the manufacturing technique as a literature on the characteristics of polymers including cadaverine.

The synthesis of novel polyamide resins incorporating cadaverine in this way can develop polyamide resins having new physical properties and is expected to be used for various applications. However, there is a problem in that cyclic by-products are generated by deammonia reaction when a new resin introducing cadaverine is produced at a high temperature and a high pressure, and a problem of color discoloration due to high temperature also occurs, Do.

WO2010-113736 discloses a method for producing an aliphatic polyamide resin by melt polycondensation reaction of biologically produced cadaverine with an aliphatic long chain diacid. This patent restricts the content of cyclic by-products of biologically produced cadaverine, but does not refer to cyclic by-products produced through polymerization, and describes only the method of preparation by melt polymerization.

Korean Patent Laid-Open Publication No. 2015-0062943 discloses the preparation of an aliphatic polyamide resin through solid-state polymerization of a prepolymer, but alicyclic diamine is used as a main monomer, and the use of cadaverine as a monomer . In this case, it is necessary to include a step of carrying out the solid phase polymerization of the prepolymer of the polyamide resin at a temperature of 200 ° C or more. In order to introduce the prepolymer into the solid-state polymerization reactor, it includes a flash process in which the polymer is flash-discharged at a high temperature and a high pressure at room temperature and atmospheric pressure. However, for the process of discharging at a normal temperature and atmospheric pressure instantaneously at high temperature and high pressure, There is a problem in that it is necessary to additionally introduce it.

Japanese Patent Application Laid-Open No. 1999-228690 discloses a method for producing a polyamide resin by solid-state polymerization of a prepolymer, but refers only to an aromatic polyamide resin, and furthermore, a technique for preventing fusion by performing solid- The solid phase polymerization is carried out at a temperature of 195 占 폚 or less in the first stage and 205 to 280 占 폚 in the second stage, and the technique is disclosed. In order to prevent fusion, the solid phase polymerization is carried out at a temperature lower than 200 deg. C in the first stage, but finally, the solid phase polymerization must be carried out at a temperature of 200 deg. Further, there is a problem that it involves a flash process in which a prepolymer is introduced into a solid-state polymerization reactor at a high temperature and a high pressure under normal temperature and atmospheric pressure, and is then discharged in the same manner as the preceding prior patent.

The present invention relates to a novel straight-chain type aliphatic polyamide resin containing cadarin which is capable of reducing cyclic by-products generated during polymerization and reducing discoloration of color occurring under high temperature and high pressure, And a method for producing an aliphatic polyamide resin.

(A) preparing a prepolymer by adding a dicarboxylic acid, a diamine, and a solvent to the first reactor and preliminarily polymerizing the mixture; (b) discharging and solidifying the temperature of the prepolymerized prepolymer while keeping the temperature higher than the melting point of the prepolymerized prepolymer; And (c) introducing the solidified prepolymer into a second reactor to solid-phase-polymerize at a temperature of less than 200 ° C. The present invention also provides a method for producing a linear aliphatic polyamide resin.

And the dicarboxylic acid is a straight chain aliphatic dicarboxylic acid having 4 to 14 carbon atoms and the diamine is cadaverine.

And the amount of the solvent is 20 to 70 parts by weight based on 100 parts by weight of the total amount of the raw materials to be fed into the first reactor.

The prepolymerization may be carried out by: i) substituting the first reactor with an inert gas, raising the temperature to 1 to 20 ° C above the melting point of the added dicarboxylic acid, and then stirring for 10 minutes to 3 hours to form a polyamide salt ; And ii) raising the temperature of the first reactor to 200 to 250 ° C and then carrying out a prepolymerization reaction while maintaining a pressure of 5 to 30 bar for 30 to 300 minutes to prepare a prepolymer. The present invention provides a method for producing a chain aliphatic polyamide resin.

The present invention also provides a process for producing a linear aliphatic polyamide resin, wherein a terminal sealing agent, which is a monocarboxylic acid, is further added to the first reactor, and the amount of the terminal sealing agent is 0.001 to 0.1 equivalent based on the dicarboxylic acid .

And the temperature higher than the melting point of the prepolymer is 200 to 250 ° C. The present invention also provides a method for producing the linear aliphatic polyamide resin.

And the pressure of the first reactor during discharge of the prepolymer is equal to the pressure outside the first reactor.

Wherein the solid phase polymerization is carried out by continuously introducing an inert gas into the second reactor or under a vacuum of 1 torr or less.

The relative viscosity (RV) of the prepolymer prepared in the step (a) is 1.0 to 2.0, and the relative viscosity (RV) of the polymerized polymer after the step (b) is 2.0 to 4.0. Amide resin.

And the cyclic byproduct content of the polymerized polymer after step (b) is 10 mol% or less.

According to the present invention, in the production of a linear aliphatic polyamide resin containing cadaverine, solid phase polymerization is carried out after preparation of a prepolymer, and the temperature of the prepolymer is kept higher than the melting point of the prepolymer to be polymerized during the discharge of the prepolymer, There is provided a process for producing a linear aliphatic polyamide resin which can perform solid phase polymerization at a low temperature of less than 200 占 폚 without introduction of a process to reduce cyclic by-products generated during polymerization and reduce color discoloration occurring under high temperature and high pressure .

In addition, instead of applying the conventional melt polymerization process, the linear aliphatic polyamide resin can be produced at a low temperature of less than 200 ° C to increase the thermal efficiency, thereby providing price competitiveness to the final product. There is an advantage that the manufacturing method of the new method according to the present invention can be applied immediately to the existing production line without.

Hereinafter, preferred embodiments of the present invention will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, when an element is referred to as "including " an element, it means that it can include other elements, not excluding other elements, unless specifically stated otherwise.

The present inventors have conducted intensive studies to obtain a method capable of performing solid-state polymerization at a low temperature of less than 200 ° C without introducing a flash process in the production of a linear aliphatic polyamide resin. As a result, it has been surprisingly found that solid phase polymerization is carried out after preparation of a prepolymer, When the temperature of the prepolymer is maintained at a temperature higher than the melting point of the prepolymer to be polymerized, the solid phase polymerization is carried out at a low temperature of less than 200 ° C without introduction of a flash process to reduce cyclic byproducts generated during polymerization, It is possible to provide a method of producing a linear aliphatic polyamide resin capable of reducing the discoloration of color occurring, leading to the present invention.

Accordingly, the present invention provides a process for producing a prepolymer, comprising: (a) adding a dicarboxylic acid, a diamine and a solvent to a first reactor and then preliminarily polymerizing to prepare a prepolymer; (b) discharging and solidifying the temperature of the prepolymerized prepolymer while keeping the temperature higher than the melting point of the prepolymerized prepolymer; And (c) introducing the solidified prepolymer into a second reactor to solid-phase-polymerize at a temperature of less than 200 ° C to produce a linear aliphatic polyamide resin.

The first polymerization step

In the present invention, the first polymerization step is a step of prepolymerizing polyamide resin by solution polymerization in a first reactor and then discharging it to prepare a prepolymer, which can be carried out according to the following solution polymerization and discharge method of polyamide resin.

First, the dicarboxylic acid and the solvent are introduced into the first reactor, and then the liquid type diamine is then introduced into the first reactor. Here, the first reactor is not particularly limited as long as it is a reactor capable of solution polymerization of a known polyamide resin.

The dicarboxylic acid component used as a raw material for producing a polyamide resin in the present invention is a linear aliphatic dicarboxylic acid, preferably a straight chain aliphatic dicarboxylic acid having 4 to 14 carbon atoms, such as succinic acid ), Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid and the like, preferably sebacic acid or dodecanedioic acid, Can be used.

The diamine component used as a raw material for producing a polyamide resin in the present invention is a straight chain aliphatic diamine. The diamine component used in the production of the polyamide resin can be used without limitation. However, in the present invention, In view of the problems to be solved by the present invention, there is proposed a method capable of performing solid-state polymerization at a low temperature of less than 200 캜 without introducing a flash process, while improving problems such as generation of cyclic byproducts and high- It is preferable to select cadaverine. The cadaverine may be either petrochemical-derived or bio-derived, and may have a purity of 95% or more, preferably 98% or more.

In the present invention, the equivalent ratio of the dicarboxylic acid component to the diamine component is preferably in the range of 1: 1 to 1: 4, more preferably in the range of 1: 1 to 1: 4 in consideration of the reaction yield and the prepolymer production efficiency. 1.2, and most preferably in the range of 1: 1 to 1: 1.05.

The solvent is not particularly limited as long as it is a solvent used in the solution polymerization of a conventional polyamide resin. For example, water, methanol, ethanol and the like can be used, and water can be preferably used. By performing the polymerization using the above solvent, deterioration and solidification of the polymer generated during polymerization can be prevented. The solvent content is preferably 20 to 70 parts by weight, more preferably 30 to 60 parts by weight, and most preferably 40 to 50 parts by weight, based on 100 parts by weight of the total weight of the raw materials to be added. When the content of the solvent is less than 20 parts by weight, the effect of introducing a solvent for preventing deterioration and solidification during polymerization may be insignificant. If the content of the solvent is more than 70 parts by weight, the time required for removing the solvent may become longer.

Next, the catalyst and the end sealant may be added to the first reactor in addition to the monomer component and the solvent, and the catalyst and the end sealant may be introduced by itself or dissolved in a solvent.

As the catalyst in the present invention, a phosphorus-based catalyst may be used, and for example, phosphoric acid, phosphorous acid, hypophosphorous acid, phosphates, phosphites, hypophosphites and the like may be used, more preferably hypophosphite may be used. However, the catalyst is not particularly limited as long as it is a substance which does not inhibit the polymerization reaction among the phosphorus compounds in addition to the above-mentioned substances. When the phosphorus catalyst is applied to the polymerization reaction, the catalyst not only accelerates the polymerization reaction but also acts as a thermal stabilizer for the polymerization reaction. Therefore, it is preferable to use the phosphorus compound as a catalyst. The amount of the phosphorus compound to be used is preferably 10 to 5,000 ppm, more preferably 30 to 1,000 ppm, and most preferably 50 to 300 ppm based on the polymerized product. If the amount of the catalyst used is less than 10 ppm, the action of the catalyst may not be sufficiently exhibited. If the amount of the catalyst is more than 5,000 ppm, the decomposition reaction may occur during processing due to the catalyst remaining in the final product.

In the present invention, the end sealant is added to control the molecular weight. For example, a monocarboxylic acid or a monoamine of a monofunctional group may be used. In the present invention, the solid encapsulant is promoted, It is preferable to use a monocarboxylic acid.

Wherein the monocarboxylic acid end-capping agent is selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, carraic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutylic acid Alicyclic monocarboxylic acids such as aliphatic monocarboxylic acids and cyclohexanecarboxylic acids, aromatic monocarboxylic acids such as benzoic acid, toluic acid, naphthalenecarboxylic acid and phenylacetic acid, And acetic acid with good solubility.

The content of the end sealant is preferably 0.001 to 0.1 equivalents, more preferably 0.002 to 0.1 equivalents, and most preferably 0.005 to 0.1 equivalents, relative to the amount of the dicarboxylic acid to be added. If the content of the end-capping agent is less than 0.001 equivalent, the effect of controlling the molecular weight may be insignificant, and if it exceeds 0.1 equivalent, it may be difficult to obtain a desired high molecular weight polymer product.

Next, a prepolymer is prepared by forming a polyamide salt in a first reactor into which the above components are introduced, and then performing a prepolymerization reaction.

The formation of the polyamide salt can be carried out, for example, by sufficiently replacing the first reactor with an inert gas such as nitrogen or argon at room temperature, then completely sealing the reactor and adding 1 to 20 ° C, The temperature is elevated to a high temperature of 10 ° C, and when the temperature is elevated, stirring is carried out at that temperature for 10 minutes to 3 hours, preferably 30 minutes to 1 hour, so that the polyamide salt is completely formed.

Thereafter, the temperature of the first reactor is raised to 200 to 250 ° C, preferably 210 to 230 ° C, and then the temperature is raised to 5 to 30 bar, preferably 15 to 20 bar, for 30 to 300 minutes, preferably 60 to 180 minutes The prepolymerization reaction proceeds while maintaining the pressure to prepare the prepolymer. At this time, the inner solvent and the resulting condensate may be removed to maintain the pressure inside the first reactor.

Next, the polymerized polymerized by the prepolymerization reaction is discharged to prepare a solidified prepolymer.

The discharge of the prepolymer may be performed by gradually lowering the pressure inside the first reactor after the formation of the polyamide salt to bring the pressure of the reactor to the same pressure as the pressure externally of the first reactor and then opening and discharging the resulting prepolymer at the bottom of the first reactor have. At this time, the cooling water can be discharged, but it is not limited thereto, and it is of course possible to discharge the air into the air. The cooling water may be cooled to room temperature. However, the temperature of the cooling water is not limited thereto. For example, cooling water at a temperature of 5 to 35 ° C may be used if there is no particular problem in solidification of the polymer during discharge of the generated prepolymer , Preferably 10 to 30 DEG C, may be used.

On the other hand, the 'same pressure' refers to the case where no external pressure is applied to the reactor after opening the discharge portion, so that the pressure of the reactor is completely matched to the external pressure and the external pressure is applied. May be understood to mean a state in which there is a slight pressure difference of about 1 atm, preferably within 0.5 atm, by means such as blowing.

Here, in the present invention, in order to perform an effective discharging process without using the conventional flash process under the above-described pressure condition, the temperature of the first reactor at the time of discharging is set to be 5 to 30 ° C, preferably 10 to 20 ° C higher than the melting point of the generated prepolymer Can be set. The temperature higher than the melting point of the prepolymer specifically produced may be 200 to 250 ° C, preferably 210 to 240 ° C, and most preferably 225 to 235 ° C. Thereafter, the pre-polymerized prepolymer may be pelletized to be used in a subsequent solid-state polymerization process.

On the other hand, the prepolymer prepared through the process described above has a low molecular weight ranging from 1.0 to 2.0 in terms of relative viscosity (RV, concentration of 1 g / dl with 98% sulfuric acid as a solvent) And it was confirmed that polymerization could be carried out at a low temperature in the subsequent solid phase polymerization.

Conventional polyamide production processes are difficult to melt-polymerize due to their high melting point (Tm), so that solid-state polymerization is carried out. For example, in the case of polyphthalamide (PPA), solid phase polymerization is mainly carried out, since a melting point of 300 ° C or higher is required and a temperature of 300 ° C or higher is required for melt polymerization. Therefore, a temperature lower than the melting point of the polyphthalamide resin The solid phase polymerization is carried out. Therefore, in this case, ejection is not possible unless the flash process is used in the prepolymerization process. That is, in the case of the polyphthalamide, the prepolymerization is carried out at a temperature of about 230 to 250 ° C. At this temperature, the polyphthalamide is not hardly discharged when the solvent is not present. Therefore, It is necessary to adopt a flash process for instantaneously discharging it together with water.

On the other hand, in the first polymerization step of the present invention, when a polyamide resin having a certain level of melting point is to be prepared, the flash process used in conventional polyamide polymerization is not employed, the solvent is completely removed to atmospheric pressure, In addition, there is a merit that it is possible to apply directly to an existing production line because it is not necessary to introduce additional equipment for the flash process. In addition, when performing solid phase polymerization at a low temperature of less than 200 캜, There is an effect of producing a polyamide resin having physical properties and quality equal to or higher than those of the polyamide resin.

Second polymerization step

In the present invention, the second polymerization step is a step of performing solid phase polymerization using the prepolymer on the pellet prepared in the first polymerization step in the second reactor.

The second reactor used for solid phase polymerization is not particularly limited as long as it is a reactor capable of solid phase polymerization of a known polyamide resin, and can be carried out using, for example, a fluidized bed reactor or a tumbler reactor.

In the solid phase polymerization reaction, the prepolymer prepared in the first polymerization step is introduced into the second reactor. In the present invention, however, the prepolymer introduced into the second reactor is not obtained through the conventional flash process, The temperature of the reactor is kept higher than the melting point of the prepolymer to be polymerized, and the polyamide resin thus obtained is discharged at a temperature higher than the melting point of the prepolymer to be polymerized. Is produced.

Thus, in the present invention, the solid state polymerization is carried out at a temperature of less than 200 ° C, preferably greater than 150 ° C and less than 200 ° C, more preferably greater than 170 ° C and less than 200 ° C. In this case, the polymerization time may be suitably set in the range of 1 to 48 hours, preferably 5 to 24 hours, in consideration of generation of cyclic byproducts and color discoloration.

In addition, the solid state polymerization may be carried out by continuously introducing an inert gas, or may be carried out by applying a vacuum. Any of the two methods may be employed. Nitrogen is preferably used as the inert gas, and when the solid-state polymerization is carried out through vacuum, the vacuum is preferably made to be 1 torr or less.

The polymer produced through the solid phase polymerization has a relative viscosity (RV, analysis of 98% sulfuric acid as a solvent at a concentration of 1 g / dl) in the range of 2.0 to 4.0, It is suitable for application to materials. The cyclic byproduct content of the polymerized product produced through the solid phase polymerization is 10 mol% or less, preferably 8 mol% or less, more preferably 5 mol% or less, still more preferably 3 mol% or less, Can be significantly reduced.

Thus, in the second polymerization step of the present invention, solid-state polymerization is carried out at a low temperature of less than 200 ° C, color discoloration is reduced and color characteristics are excellent, and generation of cyclic by-products generated in the polymerization of a polyamide resin containing cadaverine The present invention can provide a method for producing a polyamide resin capable of dramatically reducing the amount of the polyamide resin. Particularly, in the polymerization of a polyamide resin containing cadaverine, the generation of piperidine end groups by cyclization of cadaverine at the end of the reactor can be reduced, and the inhibition of the polymer production reaction by terminal group capping can be minimized, It is possible to manufacture a linear fatty acid polyamide resin containing cadaverine.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1

1,700 g (47 parts by weight based on 100 parts by weight total) of sodium cyanoborohydride, 132 mg (1.25 mmol, 79 ppm based on the final polymer) of sodium hypophosphite, 1,260 g (6.23 mol, 1.00 eq) of sebacic acid, 650 g (6.36 mol, 1.02 eq) (0.03 mol, 0.005 eq) of acetic acid were charged into a 10 L high-pressure reactor and then purged with nitrogen at room temperature for 10 minutes. After the reactor was completely closed, the temperature was raised to 140 占 폚. After the heating was completed, the mixture was stirred at 140 DEG C for 30 minutes to completely form the polyamide salt. Then, the temperature was set at 230 ° C, and the temperature was gradually raised. When the temperature reached 210 ° C, the pressure was 17.2 bar, and the pressure was maintained while gradually removing water. The reaction temperature gradually reached 230 DEG C to maintain the above pressure. After reaching 230 [deg.] C, the pressure in the reactor was slowly reduced to atmospheric pressure once the pressure could no longer be maintained. When the atmospheric pressure was reached, the discharge portion at the bottom of the reactor was opened to discharge the generated prepolymer to the cooling water. The total reaction time required 300 minutes including the temperature rise time.

The prepared prepolymer was pulverized, and then 300 g was put into a 5 L tumbler reactor, and then it was closed and slowly rotated at 10 rpm. The internal oxygen was firstly removed by rotating the reactor at room temperature for 15 minutes while applying a vacuum so that the internal pressure of the reactor became 1 torr or less. Thereafter, the temperature was gradually raised to reach 190 캜, and solid state polymerization was carried out at 190 캜 for 5 hours. The polymerized solid product was discharged into cooling water to prepare a final polyamide resin.

Example 2

(633 mol, 1.02 eq), distilled water 170 g (47 parts by weight based on 100 parts by weight total), 13.2 mg (0.12 mmol, based on the final polymer 79 ppm) of sodium hypophosphite, and 187 mg (31 mmol, 0.005 eq) was introduced into a 1 L high-pressure reactor and then purged with nitrogen at room temperature for 10 minutes. After the reactor was completely closed, the temperature was raised to 140 占 폚. After the heating was completed, the mixture was stirred at 140 DEG C for 30 minutes to completely form the polyamide salt. Then, the temperature was set at 230 ° C, and the temperature was gradually raised. When the temperature reached 210 ° C, the pressure was 17.2 bar, and the pressure was maintained while gradually removing water. The reaction temperature gradually reached 230 DEG C to maintain the above pressure. After reaching 230 [deg.] C, the pressure in the reactor was slowly reduced to atmospheric pressure once the pressure could no longer be maintained. When the atmospheric pressure was reached, the discharge portion at the bottom of the reactor was opened to discharge the generated prepolymer to the cooling water. The total reaction time required 300 minutes including the temperature rise time.

The prepared prepolymer was pulverized, and then 50 g was added to the fluidized bed reactor. Nitrogen at 180 캜 was blown into the reactor at a rate of 5 L / m 2 and solid phase polymerization was carried out for 24 hours to prepare a final polyamide resin.

Comparative Example

1,700 g (47 parts by weight based on 100 parts by weight total) of sodium cyanoborohydride, 132 mg (1.25 mmol, 79 ppm based on the final polymer) of sodium hypophosphite, 1,260 g (6.23 mol, 1.00 eq) of sebacic acid, 650 g (6.36 mol, 1.02 eq) (0.03 mol, 0.005 eq) of acetic acid were charged into a 10 L high-pressure reactor and then purged with nitrogen at room temperature for 10 minutes. After the reactor was completely closed, the temperature was raised to 140 캜. After the heating was completed, the mixture was stirred at 140 DEG C for 30 minutes to completely produce the polyamide salt. Then, the temperature was set at 230 ° C, and the temperature was gradually raised. When the temperature reached 210 ° C, the pressure was 17.2 bar, and the pressure was maintained while gradually removing water. The reaction temperature gradually reached 230 DEG C to maintain the above pressure. After reaching 230 [deg.] C, the pressure in the reactor was slowly reduced to atmospheric pressure once the pressure could no longer be maintained. The temperature of the autoclave reactor was raised to 270 ° C for 20 minutes, and then the autoclave was further maintained at a normal pressure for 50 minutes and under a vacuum of 1 torr or less for 10 minutes. After completion of the polymerization, the discharged portion of the bottom was opened, and the resulting polymer was discharged into cooling water and pelletized to prepare a final polyamide resin. The total reaction time was 380 minutes including the temperature rise time.

Test Example

The melting point (Tm), the crystallization temperature (Tc), the relative viscosity (RV), the cyclic byproduct content, and the color of the polyamide resin prepared according to the Examples and Comparative Examples were measured in the following manner. Respectively.

[How to measure]

1) Melting point (Tm) and crystallization temperature (Tc)

The melting point and the crystallization temperature were confirmed by differential scanning calorimetry (DSC). The temperature was raised from 20 ° C to 300 ° C at a rate of 10 ° C / min, then gradually cooled to 10 ° C / min and then increased again.

2) Relative viscosity (RV)

Using 98% sulfuric acid as a solvent, a sample having a concentration of 1 g / dl was analyzed at 25 캜 using a Ubbelohde viscosity tube according to the following equation (1).

[Equation 1]

RV =? /? ₀

(η is the number of drops of the solution in which the sample is dissolved, and η ₀ is the number of drops of the solvent in which the sample is not dissolved)

3) Structure of polymer and content of terminal short-term piperidine by cyclodextrin cyclization reaction

Nuclear Magnetic Resonance (NMR) analysis confirmed the structure of the polymer and the content of piperidine in the terminal group by cyclization of cadaverine. A small amount of the polyamide to be analyzed was dissolved in Hexafluoro-2-propanol (HFIP) solution, and a small amount of the polyamide was analyzed by ¹ H-NMR analysis using CDCl ₃ NMR solvent. ¹ H-NMR analysis was carried out by confirming the structure of the polymer product through the position and integral value of ¹ H-NMR peak. (Chemical shift value: 3.0 to 3.5 ppm) bonded to the carbon adjacent to the nitrogen atom of the amide bond of the polyamide main chain and hydrogen bonded to the carbon adjacent to the nitrogen atom of the nitrogen hetero ring (chemical shift value: 3.5 to 4.0 ppm ) To calculate the content of the cyclic byproducts. ≪ tb >< TABLE >

4) Color

The polymer product was visually observed.

Referring to the above Table 1, there is no difference in the thermal properties and the viscosity characteristics of the final product through the melt polymerization (Comparative Example) and the solid phase polymerization (Examples 1 and 2), but in the case of the cyclic byproduct content and color characteristics, It can be confirmed that it is superior in the examples.

That is, in the prepolymerization of the polyamide resin according to the present invention, when the prepolymer is discharged while maintaining the temperature of the prepolymer higher than the melting point of the prepolymer to be polymerized, It can be confirmed that not only polymerization can be effectively promoted to obtain a polymer product having a high molecular weight but also the production of cyclic byproducts occurring upon polymerization and the color discoloration occurring under high temperature and high pressure are dramatically reduced.

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are to be construed as being included within the scope of the present invention do.

Claims (10)

(a) adding a dicarboxylic acid, a diamine and a solvent to a first reactor and preliminarily polymerizing to prepare a prepolymer;
(b) discharging and solidifying the temperature of the prepolymerized prepolymer while keeping the temperature higher than the melting point of the prepolymerized prepolymer; And
(c) introducing the solidified prepolymer into a second reactor to solid-phase polymerize at a temperature of less than 200 ° C;
Lt; / RTI >
In the step (a), the dicarboxylic acid is a straight chain aliphatic dicarboxylic acid having 4 to 14 carbon atoms, the diamine is cadaverine,
The temperature higher than the melting point of the prepolymer in step (b) is 200 to 250 ° C,
The step (b) may include removing the solvent before discharging the prepolymer, reducing the pressure of the first reactor,
Wherein the cyclic byproduct content of the polymerized polymer after step (c) is 10 mol% or less. delete The method according to claim 1,
Wherein the amount of the solvent is 20 to 70 parts by weight based on 100 parts by weight of the total weight of raw materials including the solvent to be added to the first reactor. The method according to claim 1,
The prepolymerization is carried out by: i) substituting the first reactor with an inert gas, raising the temperature to 1 to 20 ° C above the melting point of the added dicarboxylic acid, and then stirring for 10 minutes to 3 hours to form a polyamide salt step; And ii) raising the temperature of the first reactor to 200 to 250 ° C and then performing a prepolymerization reaction while maintaining a pressure of 5 to 30 bar for 30 to 300 minutes to form a prepolymer. A method for producing a chained aliphatic polyamide resin. The method according to claim 1,
Wherein the end sealant is further added to the first reactor and the amount of the end sealer is 0.001 to 0.1 equivalent based on the dicarboxylic acid. delete delete The method according to claim 1,
Wherein the solid-state polymerization is carried out by continuously introducing an inert gas into the second reactor, or is carried out under a vacuum of 1 torr or less. The method according to claim 1,
Wherein the relative viscosity (RV) of the prepolymer prepared in the step (a) is 1.0 to 2.0 and the relative viscosity (RV) of the polymerized polymer after the step (b) is 2.0 to 4.0. Resin. delete