METHOD FOR PREPARING POLYAMIDE BY USING MOLECULAR WEIGHT CONTROL AGENT HAVING DOUBLE ACTIVE GROUP, AND POLYAMIDE PREPARED THEREBY

Abstract

Provided are a method for preparing a polyamide by using a molecular weight controller having a double active group in anionic ring-opening copolymerization of a polyamide, thereby enabling molecular weight to be controlled through the addition reaction of the molecular weight controller, and a polyamide prepared thereby.

Claims

1. A method for preparing a polyamide which includes a molecular weight controller having a double active group by an anionic polymerization reaction, wherein lactam, and based on 100 parts by weight of the entire lactam, 0.01 parts by weight to 20 parts by weight of an alkali metal as an initiator, 0.01 parts by weight to 5.0 parts by weight of a compound represented by Formula 2 as a molecular weight controller having a double active group, and a compound represented by Formula 1 using 0.01 parts by weight to 5.0 parts by weight of an activator are included: ##STR00006## wherein n and m are each independently a rational number satisfying n=m or n>m, and k is a rational number satisfying a condition that a weight average molecular weight (Mw) of the compound represented by Formula 1 is in a range of 20,000 g/mol to 100,000 g/mol, ##STR00007##

2. The method of claim 1, wherein the lactam comprises at least one selected from the group consisting of caprolactam, laurolactam, pyrrolidone, piperidinone, and any mixture thereof.

3. The method of claim 2, wherein two materials selected as the lactam are included at a weight ratio of 20 to 80:80 to 20.

4. The method of claim 1, wherein the activator comprises at least one selected from the group consisting of carbon dioxide (CO.sub.2), benzoyl chloride, N-acetyl caprolactam, N-acetyl laurolactam, octadecyl isocyanate (SIC), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and any mixture thereof.

5. The method of claim 1, wherein the alkali metal comprises at least one selected from the group consisting of metal hydride, metal hydroxide, and metal alkoxide.

6. The method of claim 1, wherein the polymerization reaction is performed in a range of 160 C. to 300 C.

7. A polyamide prepared by the method of claim 1.

8. The polyamide of claim 7, wherein the polyamide has a polydispersity index (PDI) of 4 or less.

9. The polyamide of claim 7, wherein a weight average molecular weight (Mw) of the polyamide is in a range of 20,000 g/mol to 100,000 g/mol.

10. The polyamide of claim 7, wherein the polyamide has a linear, branched, hyperbranched, or dendritic structure.

11. A parts material selected from the group consisting of a vehicle material, an electronic device material, an industrial pipe material, a construction engineering material, a 3D printer material, a textile material, a cladding material, a machine tool material, a medical material, an aviation material, a photovoltaic material, a battery material, a sports material, a household appliance material, a household material, and a cosmetic material, which each include the polyamide of claim 7.

Description

BRIEF DESCRIPTION OF DRAWING

[0033] FIG. 1 is a graph showing the result of .sup.13C-NMR analysis of a molecular weight controller prepared according to the present invention.

[0034] FIG. 2 is a graph showing the result of DSC analysis of the molecular weight controller prepared according to the present invention.

BEST MODE

[0035] The present invention will be described with reference to specific embodiments and the accompanying drawings. The embodiments will be described in detail in such a manner that the present invention may be carried out by those of ordinary skill in the art. It should be understood that various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain shapes, structures, and features described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in connection with one embodiment.

[0036] Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims and the entire scope of equivalents thereof, if properly explained.

[0037] In addition, unless otherwise specified in the present specification, the term substitution or substituted means that one or more hydrogen atoms in the functional groups of the present invention are substituted with one or more substituents selected from the group consisting of a halogen atom (F, Cl, Br, or I), a hydroxy group, a nitro group, a cyano group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group, an ester group, a ketone group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alicyclic organic group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted heteroaryl group, and a substituted or unsubstituted heterocyclic group. These substituents may be linked to each other to form a ring.

[0038] In the present invention, unless otherwise specified, the term substituted means that a hydrogen atom is substituted with a substituent such as a halogen atom, a C.sub.1-C.sub.20 hydrocarbon group, a C.sub.1-C.sub.20 alkoxy group, and a C.sub.6-C.sub.20 aryloxy group.

[0039] In addition, unless otherwise specified, the term hydrocarbon group refers to a linear, branched, or cyclic saturated or unsaturated hydrocarbon group. The alkyl group, the alkenyl group, the alkynyl group, and the like may be linear, branched, or cyclic.

[0040] In addition, unless otherwise specified in the present specification, the term alkyl group refers to a C.sub.1-C.sub.30 alkyl group and the term aryl group refers to a C.sub.6-C.sub.30 aryl group. In the present specification, the term heterocyclic group refers to a group in which one to three heteroatoms selected from the group consisting of O, S, N, P, Si, and any combination thereof are contained in one ring. Examples of the heterocyclic group may include pyridine, thiophene, and pyrazine, but the present invention is not limited thereto.

[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, so that those of ordinary skill in the art can easily carry out the present invention.

[0042] As described above, since an activator used in a conventional anionic polymerization has only one carbonyl group that opens a cyclic structure in a molecular structure, there is a limitation in obtaining a polyamide having a high molecular weight.

[0043] The present invention seeks a solution to the above-described problems by providing a method for preparing a polyamide through anionic copolymerization using a molecular weight controller having a double active group in an anionic polymerization reaction.

[0044] Specifically, the present invention provides a method for preparing a polyamide, wherein a molecular weight controller by an anionic polymerization reaction is included.

[0045] Lactam, and based on 100 parts by weight of the entire lactam, 0.01 parts by weight to 20 parts by weight of an alkali metal as an initiator, 0.01 parts by weight to 5.0 parts by weight of a compound represented by Formula 2 as a molecular weight controller having a double active group, and a compound represented by Formula 1 using 0.01 parts by weight to 5.0 parts by weight of an activator may be included.

##STR00003##

[0046] n and m are each independently a rational number satisfying n=m or n>m, and k is a rational number satisfying a condition that a weight average molecular weight (Mw) of the compound represented by Formula 1 is in a range of 20,000 g/mol to 100,000 g/mol.

##STR00004##

[0047] More specifically, compositions included in the preparation of the polyamide, including the amide-based molecular weight controller according to the present invention, will be described below.

[0048] First, the lactam according to the present invention is a monomer for preparing a polyamide. Laurolactam may be preferably used as the monomer. However, the present invention is not limited thereto. For example, the lactam having 4 to 12 carbon atoms may include caprolactam, piperidone, pyrrolidone, enantolactam, and caprylactam. In some cases, the lactam may include propiolactam, 2-pyrrolidone, valerolactam, caprolactam, heptanolactam, octanolactam, nonanolactam, decanolactam, undecanolactam, and dodecanolactam.

[0049] In addition, the alkali metal catalyst according to the present invention is an initiator for preparing the polyamide and may include at least one selected from the group consisting of metal hydride, metal hydroxide, and metal alkoxide as a compound that allows the formation of the laurolactam anion.

[0050] In a specific example, the metal hydride may include sodium hydride and potassium hydride, the metal hydroxide may include sodium hydroxide and potassium hydroxide, and the metal alkoxide may include potassium tert-butoxide and aluminum isopropoxide, but the present invention is not limited thereto.

[0051] The metal alkoxide may include sodium caprolactamate or potassium caprolactamate, alkaline earth metal caprolactamate, for example, magnesium bromide caprolactamate, magnesium chloride caprolactamate, or magnesium biscaprolactamate, an alkali metal, for example, sodium or potassium, alkali metal base, for example, sodium base, for example sodium hydride, sodium, sodium hydroxide, sodium methanolate, sodium ethanolate, sodium propanolate, or sodium butanolate, or at least one selected from the group consisting of potassium base, for example potassium hydride, potassium, potassium hydroxide, potassium methanolate, potassium ethanolate, potassium propanolate, potassium butanolate, or any mixture thereof, and preferably at least one selected from the group consisting of sodium caprolactate, potassium caprolactate, magnesium bromide caprolactate, magnesium chloride caprolactate, magnesium biscaprolactate, sodium hydride, sodium, sodium hydroxide, sodium ethanolate, sodium methanolate, sodium propanolate, sodium butanolate, potassium hydride, potassium, potassium hydroxide, potassium methanolate, potassium ethanolate, potassium propanolate, potassium butanolate, and any mixture thereof. In addition, at least one selected from the group consisting of sodium hydride, sodium, sodium caprolactamate, and any mixture thereof may be included.

[0052] The metal catalyst may be used in the form of a solid or a solution, and the catalyst is preferably used in the form of a solid. The catalyst is preferably added to a lactam melt in which the catalyst can be dissolved. These catalysts lead to particularly rapid reactions, thereby increasing the efficiency of the process of preparing the polyamide according to the present invention.

[0053] According to the present invention, an amount of the alkali metal catalyst may be in a range of 0.01 parts by weight to 20 parts by weight based on 100 parts by weight of the entire lactam. The amount of the alkali metal catalyst may be in a range of preferably 0.1 parts by weight to 10 parts by weight, and more preferably 0.5 parts by weight to 5 parts by weight.

[0054] In this case, when the alkali metal catalyst is added in an amount of less than 0.01 parts by weight, unpolymerization may occur or a reaction rate may decrease. When the amount of the alkali metal catalyst exceeds 20 parts by weight, a molecular weight reduction problem may occur. Therefore, the above range is preferable.

[0055] Next, preferably, the molecular weight controller according to the present invention has the double active group including a compound represented by Formula 2.

##STR00005##

[0056] In some cases, the molecular weight controller according to the present invention may be ethylene-bis-stearamide (EBS), but the present invention is not limited thereto. The molecular weight controller may include at least one selected from the group consisting of an amine compound, a urea compound, and a di-urea compound.

[0057] According to the present invention, an amount of the molecular weight controller may be in a range of 0.01 parts by weight to 5 parts by weight based on 100 parts by weight of the entire lactam. The amount of the molecular weight controller may be in a range of preferably 0.01 parts by weight to 2 parts by weight, and more preferably 0.01 parts by weight to 1 part by weight.

[0058] In this case, when the molecular weight controller is added in an amount of less than 0.01 parts by weight, a gelation (crosslinking or branching reaction) problem may occur. When the amount of the molecular weight controller exceeds 5 parts by weight, a molecular weight reduction problem may occur. Therefore, the above range is preferable.

[0059] In this regard, as shown in FIG. 1, it was confirmed from the result of .sup.13C-NMR and DSC analysis of the molecular weight controller prepared as above that, in the case of the above-described molecular weight controller, the melting temperature (Tm) was increased. From this, when the molecular weight controller is added, it can be expected that a fast reaction rate between polymerized chains in the polymerization process is controlled due to the long chain structure or the cyclic structure of the molecular weight controller itself, so that the molecular weight can be adjusted.

[0060] Finally, the activator is not particularly limited.

[0061] For example, the activator is selected from the group consisting of lactam that is N-substituted by electrophilic moiety, aliphatic diisocyanate, aromatic diisocyanate, polyisocyanate having more than two isocyanate groups, aliphatic diacylhalide, and aromatic diacyl halide. In addition, the activator (C) may include at least one selected from the group consisting of mixtures of the above-described materials.

[0062] Specifically, according to the present invention, the activator may preferably include carbon dioxide (CO.sub.2), but the present invention is not limited thereto. For example, the activator may include at least one selected from the group consisting of benzoyl chloride, N-acetyl caprolactam, N-acetyl laurolactam, octadecyl isocyanate (SIC), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and any mixture thereof.

[0063] An amount of the carbon dioxide may be in a range of 0.002 parts by weight to 1.0 part by weight based on 100 parts by weight of the entire lactam. The amount of the carbon dioxide may be in a range of preferably 0.005 parts by weight to 0.5 parts by weight, and more preferably 0.01 parts by weight to 0.1 parts by weight.

[0064] In this case, when the carbon dioxide is added in an amount of less than 0.002 parts by weight, unpolymerization may occur or a reaction rate may decrease. When the amount of the carbon dioxide exceeds 1.0 part by weight, a gelation or depolymerization problem may occur. Therefore, the above range is preferable.

[0065] Hereinafter, preferred examples are presented so as to help the understanding of the present invention. However, the following examples are for illustrative purposes only and the present invention is not limited by the following examples.

Preparation Example

Preparation of Molecular Weight Controller (isophthaloyl-bis-laurolactam (IBL)

[0066] A stirrer, a reflux condenser tube, and a dropping funnel were installed in a 3-neck flask. At this time, all glass wares were previously dried in a nitrogen atmosphere, considering moisture-sensitive reactants. 1 mol eq. (197.32 g) of laurolactam as a monomer, 1 mol of triethylamine, and 500 ml of THF were added to the flask and then stirred. Triethylamine acts as a scavenger that removes hydrochloric acid produced when laurolactam and isophthaloyl chloride react with each other. The prepared mixture was stirred and cooled with ice, and a solution in which 0.5 mol eq. of isophthaloyl chloride was dissolved in 150 ml of THF was slowly added dropwise for 40 minutes. After the addition was completed, the reaction mixture was stirred at room temperature for 30 minutes and then filtered. A white solid product was dried in air and then stirred in 200 ml of water to remove a reaction by-product Et.sub.3NH.sup.+Cl.sup.. The resultant product was washed twice with 100 ml distilled water on a filter paper. A white powder was dried in a vacuum oven at 80 C. and a material was identified by using DSC and .sup.13C-NMR.

EXAMPLES

Example 1

Preparation of Polyamide Using Molecular Weight Controller (IBL) Having Double Active Group

[0067] Caprolactam and laurolactam as a monomer and NaH as an initiator were weighed to a molar ratio of 50:50:1 and added to a 3-neck flask. A temperature of an oil bath was set to 160 C., and the monomer and the initiator were primarily dissolved in a nitrogen atmosphere. After confirming that the reactants were all melted, a vacuum was applied to remove hydrogen gas generated in the reactions. After the temperature was set to 230 C. at which the polymerization reaction actually occurred, 0.05 mol of the molecular weight controller and 0.15 mol of the activator (TDI) based on 100 mol of the lactam were added. When the polymerization was completed, a 1:1 mixed solution of formic acid and water was added to terminate the reaction. The resultant product was washed several times with water and alcohol and finally dried in a vacuum oven. A sample having content shown in Table 1 was collected. A relative viscosity of each sample was confirmed and the result thereof is shown in Table 2. At this time, a 2 wt % solution was prepared by adding a polymer to 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and the relative viscosity was measured at 25 C.

TABLE-US-00001 TABLE 1 Molecular Alkali weight End-capping Caprolactam Laurolactam metal Activator controller agent Example 1 50 50 1 0.15 (TDI) 0.05 (IBL) Example 2 50 50 1 0.15 (TDI) 0.05 (IBL) 0.2 Example 3 50 50 1 0.15 (CO.sub.2) 0.05 (IBL) Comparative 50 50 1 0.15 (TDI) 0.05 (IBC) Example 1 Comparative 50 50 1 0.15 (TDI) Example 2

Example 2

[0068] A polyamide was prepared in the same manner as in Example 1, except that an end-capping agent having a molar ratio of 0.2 was added.

Example 3

[0069] A polyamide was prepared in the same manner as in Example 1, except that CO.sub.2 instead of TDI was added as an activator.

Comparative Examples

Comparative Example 1

[0070] A molecular weight controller was prepared by using isophthaloyl-bis-caprolactam instead of isophthaloyl-bis-laurolactam, toluene instead of THF, and caprolactam instead of laurolactam. A polyamide was prepared in the same manner as in Example 1 by using the molecular weight controller.

Comparative Example 2

[0071] A polymerization sample was prepared in the same manner as in Example 1, except that isophthaloyl-bis-laurolactam was not added.

TABLE-US-00002 TABLE 2 Sequence Viscosity (cps) Example 1 19 Example 2 17 Example 3 18 Comparative Example 1 Gelation Comparative Example 2 Gelation

[0072] As shown in Table 2, Comparative Examples 1 and 2 showed gelation because the molecular weight was not adjusted, as compared with Examples 1 to 3.

[0073] Although the present invention has been described with reference to the drawings according to embodiments of the present invention, it will be understood by those of ordinary skill in the art that various applications and modifications can be made thereto without departing from the scope of the present invention.