Method for producing polyamide resin, polyamide resin, and polyamide resin composition

Abstract

To provide a polyamide resin including a cyclic molecule and exhibiting resistance to decomposition and yellowing, as well as a simplified method for producing the polyamide resin.SOLUTION: A method for producing a polyamide resin, comprising polymerizing a cyclic monomer (C) having an amide bond in the presence of a compound (A) comprising at least one selected from alkali metals and alkaline earth metals, and a polymerization co-catalyst (B), wherein the polymerization co-catalyst (B) comprises a derivative of a cyclic molecule having a molecular weight of 300 g / mol or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polyamide resin having a cyclic structure, a polyamide resin, and a polyamide resin composition. [Background technology]

[0002] Polyamides have excellent mechanical properties such as rigidity and toughness, as well as excellent thermal properties, making them suitable for use as engineering plastics. Therefore, they are widely used, primarily for injection molding, in a variety of electrical and electronic components, machine components, and automobile components. Known methods for further improving the toughness of polyamide resins include blending them with olefinic elastomers or core-shell compounds in which a rubbery core layer is covered with a glassy resin shell layer (see Patent Documents 1 and 2).

[0003] On the other hand, as a method for improving impact strength and toughness, for example, a resin composition obtained by reacting a polyolefin modified with an unsaturated carboxylic acid anhydride with a polyrotaxane having a functional group (see, for example, Patent Document 3) has been proposed. Patent Document 4 also proposes a resin composition in which the toughness of a polyamide is greatly improved by adding a polyrotaxane. Furthermore, polyamide-modified polyrotaxane (see Patent Document 5) and polyamide-modified cyclodextrin (see Patent Document 6) have been proposed as modifiers with excellent compatibility with polyamide, and they have succeeded in greatly improving the toughness of polyamide while reducing the amount of polyamide modifier containing a cyclic molecule added. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-31325 [Patent Document 2] Japanese Patent Application Publication No. 5-339462 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-209460 [Patent Document 4] International Publication No. 2016 / 167247 [Patent Document 5] Japanese Patent Application Publication No. 2019-11462 [Patent Document 6] Japanese Patent Application Publication No. 2019-194304 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Documents 5 and 6, by using a polyamide resin in which a cyclic structure has been introduced into the polyamide molecular chain as a modifier, it has been possible to successfully increase toughness even when the amount of polyamide modifier added is reduced. However, the methods for producing polyamide resins described in these patent documents have a problem in that they involve many steps. In addition, these polyamide resins have problems such as decomposition due to backbiting and yellowing due to oxidation because the polyamide terminal groups are amino groups.

[0006] In view of the problems in the background art described above, an object of the present invention is to provide a polyamide resin having a cyclic structure that is resistant to decomposition and yellowing, and a simple method for producing the same. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration. (1) A method for producing a polyamide resin by polymerizing a cyclic monomer (C) having an amide bond in the presence of a compound (A) containing at least one selected from an alkali metal and an alkaline earth metal, and a polymerization co-catalyst (B), wherein the polymerization co-catalyst (B) contains a derivative of a cyclic molecule having a molecular weight of at least 300 g / mol. (2) The method for producing a polyamide resin according to (1), wherein the polymerization co-catalyst (B) has a structure represented by the following formula (I):

[0008] [ka] (n is an integer from 3 to 18.)

[0009] (3) The method for producing a polyamide resin according to (1) or (2), wherein the polymerization co-catalyst (B) is obtained by reacting a cyclic molecule having a molecular weight of at least 300 g / mol, a 5- to 20-membered cyclic lactam, and a coupling agent having at least one isocyanate group. (4) The method for producing a polyamide resin according to (3), wherein the coupling agent having at least one isocyanate group is any one selected from a diisocyanate compound and a silane coupling agent having one isocyanate group. (5) The method for producing a polyamide resin according to any one of (1) to (4), wherein the polymerization co-catalyst (B) is a derivative of cyclodextrin. (6) The method for producing a polyamide resin according to any one of (1) to (5), wherein the cyclic monomer (C) having an amide bond is a 5- to 20-membered cyclic lactam. (7) The method for producing a polyamide resin according to (6), wherein the cyclic monomer (C) having an amide bond is ε-caprolactam. (8) A polyamide resin having a cyclic structure derived from a derivative of a cyclic molecule having a molecular weight of 300 g / mol or more, and having a terminal amino group concentration of 5.0 × 10 -5 mol / g or less. (9) The polyamide resin according to (8), wherein the cyclic structure is derived from a derivative of cyclodextrin. (10) The polyamide resin according to (8) or (9), which contains a structure derived from a 5- to 20-membered cyclic lactam. (11) The polyamide resin according to (10), which contains a structure derived from ε-caprolactam. (12) A polyamide resin composition comprising at least the polyamide resin according to any one of (8) to (11) and a polyamide resin (D). [Effects of the Invention]

[0010] According to the present invention, a polyamide resin having a cyclic structure that is resistant to decomposition and yellowing can be easily obtained. Furthermore, by mixing the polyamide resin of the present invention with other polyamide resins and other additives and molding the mixture, a molded product having an excellent balance of rigidity and toughness can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will now be described in further detail.

[0012] The method for producing a polyamide resin according to the present invention involves polymerizing a cyclic monomer (C) having an amide bond (hereinafter sometimes abbreviated as cyclic monomer (C)) in the presence of a compound (A) (hereinafter sometimes abbreviated as compound (A)) containing at least one selected from alkali metals and alkaline earth metals, and a polymerization co-catalyst (B), wherein the polymerization co-catalyst (B) is a derivative of a cyclic molecule having a molecular weight of 300 g / mol or more. Using a derivative of a cyclic molecule as the polymerization co-catalyst (B) allows for the incorporation of a cyclic structure into the polyamide resin, effectively enhancing toughness. Furthermore, the polymerization method described above simplifies the polymerization process. Furthermore, the terminals of the resulting polyamide resin can be converted to formula (I) or a carboxyl group, thereby preventing decomposition and yellowing of the polyamide resin.

[0013] The compound (A) containing at least one selected from alkali metals and alkaline earth metals used in the present invention is not limited as long as it is a compound commonly used in anionic polymerization. Examples include hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide; hydrides such as sodium hydride, potassium hydride, and sodium borohydride; metal alkoxides such as lithium t-butoxide, sodium t-butoxide, potassium t-butoxide, lithium n-butoxide, sodium n-butoxide, potassium n-butoxide, lithium t-pentoxide, sodium t-pentoxide, and potassium t-pentoxide; alkyl metal compounds such as methyllithium, n-butyllithium, s-butyllithium, and t-butyllithium; metal halide salts such as lithium halides, sodium halides, potassium halides, and calcium halides; carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, and calcium carbonate; and aryl metals such as sodium naphthalene. These may be used alone or in combination of two or more.

[0014] Among these, metal alkoxides having 4 to 30 carbon atoms are preferred because they can provide polyamide resins with excellent hydrolysis resistance and high molecular weights, and metal alkoxides having 4 to 10 carbon atoms are preferred because of their high availability, and metal alkoxides having 4 to 6 carbon atoms are even more preferred. In addition, the metal species is preferably any one selected from lithium, sodium, and potassium, because it allows the production of polyamide resins with high molecular weights.

[0015] The carbon bonded to the oxygen atom (O) of the metal alkoxide is preferably tertiary. When the carbon bonded to O is tertiary, the hydrocarbon of the metal alkoxide has a bulky structure, which improves the hydrolysis resistance of the metal alkoxide and makes it less susceptible to deactivation by moisture in the reaction system. On the other hand, when the carbon bonded to O is primary or secondary, the hydrocarbon of the metal alkoxide is less likely to have a bulky structure, so the effect of improving the hydrolysis resistance of the metal alkoxide is small and it may be more susceptible to deactivation by moisture.

[0016] In an embodiment of the present invention, when a metal alkoxide having 4 to 30 carbon atoms is used as the compound (A) containing at least one selected from alkali metals and alkaline earth metals, the amount of metal alkoxide added is preferably 0.01 to 10 parts by mole per 100 parts by mole of the cyclic monomer (C) having an amide bond. When the metal alkoxide is 0.01 parts by mole or more, the polymerization rate of the polyamide resin increases and the polymerization time is shortened. When the metal alkoxide is 10 parts by mole or less, a high molecular weight polyamide resin is easily obtained. The metal alkoxide is preferably 0.05 parts by mole or more, and more preferably 5 parts by mole or less.

[0017] In the present invention, the polymerization co-catalyst (B) contains a derivative of a cyclic molecule having a molecular weight of at least 300 g / mol. The polymerization co-catalyst (B) can be obtained by reacting a cyclic molecule having a molecular weight of at least 300 g / mol, a 5- to 20-membered cyclic lactam, and a coupling agent, and has a cyclic structure derived from the cyclic molecule and a structure represented by general formula (I). There are no particular restrictions on the method for introducing the structure represented by general formula (I), but it can generally be introduced by reacting a compound having an isocyanate group or an acyl halide group, or a carboxylic acid anhydride, with a 5- to 20-membered cyclic lactam.

[0018] [ka] (n is an integer from 3 to 18.)

[0019] The cyclic molecule having a molecular weight of 300 g / mol or more is not particularly limited as long as the opening can be penetrated by a linear molecule. Preferred examples of the cyclic molecule include cyclodextrins, crown ethers, cryptands, macrocyclic amines, calixarenes, and cyclophanes. Cyclodextrins are compounds in which multiple glucose units are linked in a ring via α-1,4-bonds. Compounds selected from α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are more preferably used.

[0020] These cyclic molecules may be modified, substituted with other functional groups, or modified with grafted chains.Furthermore, they may be compounds having a rotaxane structure in which a linear molecule threads through a cyclic molecule.

[0021] Compounds with a rotaxane structure may have one or more cyclic molecules threaded by linear molecules. Preferred cyclic molecules include cyclodextrins, crown ethers, cryptands, macrocyclic amines, calixarenes, and cyclophanes. Cyclodextrins are compounds in which multiple glucose units are linked in a ring via α-1,4-bonds. Compounds selected from α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are more preferably used.

[0022] Examples of linear molecules preferably used in compounds having a rotaxane structure include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyolefins such as polybutadiene, polyisoprene, polyisobutylene, poly(acrylonitrile-butadiene), hydrogenated polybutadiene, polyethylene, and polypropylene; polyesters such as polycaprolactone, polylactic acid, polyethylene adipate, polybutylene adipate, polyethylene terephthalate, and polybutylene terephthalate; polyamides such as polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyundecaneamide (nylon 11), and polydodecanamide (nylon 12); and polysiloxanes such as polydimethylsiloxane. Among these, polyalkylene glycols are preferably used.

[0023] The molecular weight of the cyclic molecules is preferably 300 g / mol or more, more preferably 500 g / mol or more, and even more preferably 800 g / mol or more, because the effect of adding the cyclic molecules can be improved by passing the linear molecules through the openings. On the other hand, from the viewpoint of suppressing gelation during the reaction, the molecular weight is preferably 1,000,000 g / mol or less, more preferably 500,000 g / mol or less, and even more preferably 200,000 g / mol or less.

[0024] Examples of the 5- to 20-membered cyclic lactam include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-capryllactam, ω-decanolactam, ω-undecanelactam, and ω-laurolactam. These cyclic monomers may be used alone or in combination of two or more. Of these, ε-caprolactam is preferred.

[0025] The coupling agent is not particularly limited as long as it has at least a functional group that reacts with a cyclic molecule and a functional group that can react with a 5- to 20-membered cyclic lactam to obtain the structure of general formula (I).

[0026] For example, when the cyclic molecule is a molecule having a hydroxyl group such as cyclodextrins, examples of the functional group that reacts with the cyclic molecule include an isocyanate group, a glycidyl group, an epoxy group, a carboxyl group, a carboxylic acid anhydride, an acyl halide group, an alkoxysilyl group, etc. From the viewpoint of reactivity, an isocyanate group, an epoxy group, and an alkoxysilyl group are preferred, and an isocyanate group and an alkoxysilyl group are more preferred.

[0027] Examples of alkoxy groups constituting the alkoxysilyl group include methoxy, ethoxy, propoxy, and butoxy. From the viewpoint of reactivity, methoxy or ethoxy is preferred. The alkoxysilyl group may be a monoalkoxysilyl group, a dialkoxysilyl group, or a trialkoxysilyl group.

[0028] Examples of functional groups that can react with a 5- to 20-membered cyclic lactam to give the structure of general formula (I) include an isocyanate group, an acyl halide group, and a carboxylic acid anhydride, with an isocyanate group being preferred.

[0029] Examples of the coupling agent include diisocyanate compounds such as diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate, polyisocyanates, and silane coupling agents. Among these, from the viewpoints of availability and reactivity, diisocyanate compounds such as diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate, or silane coupling agents having one isocyanate group such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane are preferably used.

[0030] Furthermore, as long as the effects of the present invention are not impaired, general polymerization promoters such as acyllactams, carbamidolactams, isocyanates, acid halides, and urea derivatives may be used simultaneously. Of these, N-acyllactams are preferred.

[0031] In an embodiment of the present invention, the amount of polymerization co-catalyst (B) added is preferably 0.01 to 10 molar parts, more preferably 0.05 to 5 molar parts, relative to 100 molar parts of the cyclic monomer (C) having an amide group. When the amount of polymerization co-catalyst (B) added is 0.01 molar parts or more, the polymerization rate is improved and the effect of the cyclic molecules can be fully obtained, which is preferable. When the amount of polymerization co-catalyst (B) added is 10 molar parts or more, the cyclic molecules become cross-linking points, increasing the possibility of gelation, so 10 molar parts or less is preferable. When two or more polymerization co-catalysts are added, it is preferable that the total amount thereof falls within the above range.

[0032] In the present invention, the cyclic monomer (C) having an amide bond means a monomer having a multi-membered ring structure and having a secondary amide bond.

[0033] As the cyclic monomer (C) having an amide bond, a lactam having a 5- to 20-membered ring is preferably used. Examples include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-capryllactam, ω-decanolactam, ω-undecanelactam, and ω-laurolactam. These cyclic monomers may be used alone or in combination of two or more types as long as the polymerizability is not impaired. Among these, ε-caprolactam is preferred because the resulting polyamide resin has excellent mechanical properties.

[0034] The water content of the cyclic monomer is preferably 0.2 parts by weight or less, and more preferably 0.1 parts by weight or less, per 100 parts by weight of the cyclic monomer. A water content of 0.2 parts by weight or less makes it difficult for the metal alkoxide to be deactivated, allowing a high-molecular-weight polyamide resin to be obtained. Since the water content of a cyclic monomer typically does not exceed 0.2 parts by weight unless the monomer is left in an extremely humid open system for a long period of time, no special drying step is required under the conditions of the present invention. While a low water content in the cyclic monomer is preferred, in embodiments of the present invention, it may exceed 0.01 parts by weight per 100 parts by weight of the cyclic monomer. The water content of the cyclic monomer can be determined using a Karl Fischer moisture analyzer.

[0035] The polyamide resin of the present invention is obtained by polymerizing a cyclic monomer (C) having an amide bond in the presence of a compound (A) containing at least one selected from alkali metals and alkaline earth metals, using a derivative of a cyclic molecule having a molecular weight of at least 300 g / mol as a polymerization promoter (B).

[0036] The polymerization temperature for obtaining the polyamide resin of the present invention is not particularly limited as long as it is a temperature equal to or higher than the melting point of the raw material cyclic monomer (C), but is preferably 50°C or higher and 300°C or lower. A polymerization temperature of 50°C or higher is preferred because polymerization proceeds rapidly. A polymerization temperature of 300°C or lower is preferred because side reactions such as thermal decomposition and gelation can be suppressed. Note that when the raw material cyclic monomer (C) is ε-caprolactam, the polymerization temperature is particularly preferably 160°C or higher and 260°C or lower.

[0037] The polymerization time in this embodiment is set depending on the amounts of compound (A) and polymerization promoter (B) blended, and the target molecular weight, but is usually in the range of 10 to 120 minutes.

[0038] In an embodiment of the present invention, the raw materials may be blended in any of the following ways: (I) a compound (A) containing at least one selected from an alkali metal and an alkaline earth metal, a polymerization promoter (B), and a cyclic monomer (C), as well as additives as needed, are blended in advance and then heated to melt; (II) a compound (A) containing at least one selected from an alkali metal and an alkaline earth metal, a polymerization promoter (B), and additives as needed are directly blended with the heated and melted cyclic monomer (C); or (III) a component consisting of a compound (A) containing at least one selected from an alkali metal and an alkaline earth metal and the cyclic monomer (C), a component consisting of the polymerization promoter (B) and the cyclic monomer (C), and as needed a component consisting of the cyclic monomer (C) and additives, and the components are mixed in a state where each component is heated and melted in advance.

[0039] The polyamide resin obtained by the polymerization method has a cyclic structure derived from a derivative of a cyclic molecule of the polymerization co-catalyst (B) having a molecular weight of 300 g / mol or more, and a terminal amino group concentration of 5.0×10 -5 The terminal amino group concentration is preferably 3.0×10 mol / g or less. -5 mol / g or less, and more preferably 2.0 × 10 -5 mol / g or less. The terminal amino group concentration is 5.0×10-5 If the concentration exceeds mol / g, the resin will decompose or turn yellow when heated and melted. Furthermore, in theory, no amino terminal groups are produced according to the method for producing a polyamide resin of the present invention. Therefore, the ideal minimum concentration of terminal amino groups is 0 mol / g.

[0040] The polyamide resin of the present invention has either a structure represented by formula (I) or a carboxyl group at its terminal.

[0041] [ka] (n is an integer from 3 to 18.)

[0042] In the method of the present invention, one or more kinds of additives may be added during ring-opening polymerization as needed to obtain a polyamide resin, provided that the addition does not significantly inhibit the polymerization.

[0043] Specific examples of various additives include heat stabilizers, coupling agents such as organosilane compounds, organotitanate compounds, and organoborane compounds, plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organophosphorus compounds, nucleating agents such as organophosphorus compounds and polyether ether ketone, metal soaps such as Montan acid waxes, lithium stearate, and aluminum stearate, mold release agents such as ethylenediamine-stearic acid-sebacic acid polycondensates and silicone compounds, color inhibitors such as hypophosphites, lubricants, ultraviolet inhibitors, colorants, flame retardants, and foaming agents. When these additives are added, their amount is preferably 10 parts by weight or less, more preferably 1 part by weight or less, per 100 parts by weight of the cyclic monomer (C) to fully utilize the characteristics of the polyamide.

[0044] In the method of the present invention, in order to improve mechanical properties, other resins such as elastomers and thermoplastic resins can be added during ring-opening polymerization to obtain a polyamide resin composition. Examples of these include thermoplastic resins such as acrylonitrile / acrylic styrene resin (AAS), acrylonitrile / ethylene / propylene / diene / styrene resin (AES), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), liquid crystal polymer (LCP), ethylene / vinyl chloride copolymer (E-PVC), ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl alcohol copolymer (EVOH), chlorinated polyvinyl chloride (PVC-C), chlorinated polyethylene (PE-C), chlorinated polypropylene (CPP), wholly aromatic polyester, phenoxy resin, fluororesin, polyacrylate, polyacetal (POM), polyamideimide (PAI), polyarylate (PAR), polyetherimide (PEI), polyetheretherketone (PEEK), polyethylene (PE), cross-linked polyethylene, and polyethylene terephthalate. Examples of the resin include polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), polyoxybenzoyl ester, polycarbonate (PC), polyvinyl acetate (PVAC), polysulfone (PSF), polystyrene (PS), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), the polyamide resin (D) described below, polypropylene (PP), polymethyl methacrylate (PMMA), methylpentene polymer (TPX), and PE, PP, PPE, and PS modified with α,β-unsaturated carboxylic acids and their acid anhydrides (e.g., maleic acid, maleic anhydride, citraconic acid, citraconic anhydride, maleimide, maleic anhydride imide, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, crotonic acid, etc.), acrylic acid esters (methyl methacrylate, glycidyl methacrylate, etc.), etc.Examples of elastomers include ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, and copolymers in which a part or all of the carboxylic acid moieties in these copolymers have been converted into salts with sodium, lithium, potassium, zinc, or calcium (ionomer resins), ethylene / methyl acrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / ethyl acrylate-g-maleic anhydride copolymers ("g" represents graft, the same applies hereinafter), ethylene / methyl methacrylate-g-maleic anhydride copolymers, ethylene / ethyl acrylate-g-maleimide copolymers, ethylene / ethyl acrylate-g-N-phenylmaleimide copolymers, and partially saponified products of these copolymers, ethylene / propylene copolymers, ethylene / propylene / 1,4-hexadiene copolymers, ethylene / propylene / dicyclopentadiene copolymers, ethylene / propylene / 2,5-norbornadiene copolymers, ethylene / butene copolymers, and α,β-unsaturated copolymers thereof. Examples of suitable elastomers include copolymers modified with carboxylic acids and their acid anhydrides (e.g., maleic acid, maleic anhydride, maleimide anhydride, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, crotonic acid, etc.), acrylic acid esters (e.g., methyl methacrylate, glycidyl methacrylate, etc.), block copolymers consisting of a polymer based on at least one vinyl aromatic compound (e.g., styrene, o-methylstyrene, p-methylstyrene, α-methylstyrene, 1,3-dimethylstyrene, vinylnaphthalene, etc.) and a polymer block based on a diene compound (e.g., 1,3-pentadiene, 1,3-hexadiene, etc.), hydrogenated block copolymers of such block copolymers, copolymers modified with the above-mentioned α,β-unsaturated carboxylic acids and their acid anhydrides, acrylic acid esters, etc., polyurethane-based thermoplastic elastomers, silicone rubber, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers. These elastomers and thermoplastic resins may be used alone or in combination. The form of the added elastomer or thermoplastic resin is not important. It may be in the form of granules, powder or fibers.

[0045] Furthermore, if necessary, inorganic or organic fibrous reinforcing materials such as glass fiber, carbon fiber, asbestos fiber, and wholly aromatic polyamide fiber, or powdery or spherical fillers such as talc, wollastonite, bentonite, montmorillonite, calcium carbonate, magnesium oxide, alumina, mica, glass beads, and potassium titanate whiskers, or sliding agents such as molybdenum disulfide, carbon black, paraffin, and silicone can be incorporated. The fibrous reinforcing materials can be in any form, such as milled fiber, roving, mat, or cloth.

[0046] The polyamide resin composition of the present invention comprises at least the above-described polyamide resin and polyamide resin (D). In addition to the above-described polyamide resin and polyamide (D), the polyamide resin composition of the present invention also contains a reaction product between the above-described polyamide resin and polyamide resin (D), but it is not practical to specify the structure of the reaction product. Therefore, the present invention is specified by the components to be blended.

[0047] The polyamide resin (D) used in the polyamide resin composition of the present invention has a cyclic structure derived from a derivative of the cyclic molecule of the present invention having a molecular weight of 300 g / mol or more, and a terminal amino group concentration of 5.0×10 -5This refers to polyamide resins other than those with a densitometric value of 1 / 2 mol / g or less. Polyamide resin (D) is composed mainly of residues of amino acids, lactams, or diamines and dicarboxylic acids. Typical examples of the raw materials include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and para-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-laurolactam; aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, and 5-methylnonamethylenediamine; aromatic diamines such as metaxylylenediamine and paraxylylenediamine; 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, and bicyclohexane. Examples of suitable polyamides include alicyclic diamines such as bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid. In the present invention, two or more polyamide homopolymers or copolymers derived from these raw materials may be blended.

[0048] Specific examples of the polyamide resin (D) include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sebacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene adipamide (nylon 106), polydecamethylene sebacamide (nylon 612), Nylon 1010), Polydecamethylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecanamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide copolymer (Nylon 66 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon Nylon 66 / 6I), Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 6T / 6I), Polyhexamethylene terephthalamide / Polydodecanamide copolymer (Nylon 6T / 12), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6T / 6I), Polyxylylene adipamide (Nylon XD6), Polyxylylene sebacamide (Nylon XD10), Polyhexamethylene terephthalamide / Poly Examples include pentamethylene terephthalamide copolymer (nylon 6T / 5T), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polypentamethylene terephthalamide / polydecamethylene terephthalamide copolymer (nylon 5T / 10T), polynonamethylene terephthalamide (nylon 9T), polydecamethylene terephthalamide (nylon 10T), polydodecamethylene terephthalamide (nylon 12T), and copolymers thereof. Two or more of these may be blended. Here, " / " indicates a copolymer, and the same applies below.

[0049] In the resin composition of the present invention, the melting point of the polyamide resin (D) is preferably 150° C. or higher and lower than 300° C. If the melting point is 150° C. or higher, heat resistance can be improved. On the other hand, if the melting point is lower than 300° C., the processing temperature during production of the resin composition can be kept appropriately low, and thermal decomposition can be suppressed.

[0050] Here, the melting point of the polyamide resin (D) in the present invention is defined as the temperature of an endothermic peak that appears when the polyamide is cooled from a molten state to 30°C at a rate of 20°C / min under an inert gas atmosphere using a differential scanning calorimeter, and then heated to the melting point + 40°C at a rate of 20°C / min. However, if two or more endothermic peaks are detected, the temperature of the endothermic peak with the greatest peak intensity is taken as the melting point.

[0051] Specific examples of polyamides having a melting point of 150°C or higher and lower than 300°C include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polypentamethylene adipamide (nylon 56), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecane amide (nylon 11), polydodecanamide (nylon 12), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polyhexamethylene adipamide / polyhexamethylene isoflurane copolymer (nylon 6 / 6T), and the like. Examples of suitable acrylic copolymers include polyhexamethylene terephthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyxylylene adipamide (nylon XD6), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polynonamethylene terephthalamide (nylon 9T), and copolymers thereof. Two or more of these may be blended.

[0052] Although there are no particular limitations on the degree of polymerization of the polyamide resin (D), it is preferable that the relative viscosity, measured at 25°C in a 98% concentrated sulfuric acid solution with a resin concentration of 0.01 g / ml, be in the range of 1.5 to 5.0. A relative viscosity of 1.5 or higher can further improve the toughness, rigidity, abrasion resistance, fatigue resistance, and creep resistance of the resulting molded article. A relative viscosity of 2.0 or higher is more preferable. On the other hand, a relative viscosity of 5.0 or lower results in excellent fluidity and therefore excellent moldability.

[0053] The resin composition of the present invention may further contain fillers, thermoplastic resins other than polyamide resins, various additives, etc., within the scope of not impairing the object of the present invention. These may be mixed by, for example, melt kneading.

[0054] The method for producing the polyamide resin composition of the present invention is not particularly limited, and examples thereof include a method in which polyamide resin (D) is polymerized simultaneously with the polymerization of the polyamide resin of the present invention, a method in which polyamide resin (D) is added during the polymerization of the polyamide resin of the present invention and mixed, kneaded in a molten state, or mixed in a solution state, etc. From the viewpoint of simplicity of the production method, a method in which polyamide resin (D) is polymerized simultaneously with the polymerization of the polyamide resin of the present invention, or a method in which polyamide resin (D) is added during the polymerization of the polyamide resin and kneaded in a molten state is preferred.

[0055] When simultaneously polymerizing a polyamide resin and a polyamide resin (D), it is preferable to simultaneously use, in addition to the polymerization cocatalyst (B) of the present invention, a general polymerization cocatalyst such as an acyllactam, a carbamidolactam, an isocyanate, an acid halide, or a urea derivative. Among these, N-acyllactams are preferred. In this case, the polymerization cocatalyst (B) of the present invention is preferably 0.1 mol % or more, more preferably 0.5 mol % or more, and even more preferably 1.0 mol % or more, based on a total of 100 mol % of the polymerization cocatalyst (B) of the present invention and the general polymerization cocatalyst. By using a content of 0.1 mol % or more, the toughness-improving effect of the cyclic structure can be exerted.

[0056] Examples of the melt kneading device for kneading the polyamide resin and the polyamide resin (D) in a molten state include extruders such as a single-screw extruder, a twin-screw extruder, a multi-screw extruder such as a four-screw extruder, a twin-screw composite extruder, etc., and kneaders. From the viewpoint of productivity, an extruder capable of continuous production is preferred, and from the viewpoint of improving kneading properties, reactivity, and productivity, a twin-screw extruder is more preferred.

[0057] Hereinafter, an example of producing the resin composition of the present invention using a twin-screw extruder will be described. From the viewpoint of suppressing thermal degradation and further improving toughness, the maximum resin temperature is preferably 300°C or lower. On the other hand, the maximum resin temperature is preferably equal to or higher than the melting point of the polyamide resin (D). Here, the maximum resin temperature refers to the highest temperature measured using resin thermometers evenly installed at multiple positions on the extruder.

[0058] The extrusion rate of the resin composition is preferably 0.01 kg / h or more, more preferably 0.05 kg / h or more, per 1 rpm of screw rotation from the viewpoint of further suppressing thermal degradation of the polyamide resin and polyamide resin (D). On the other hand, from the viewpoint of efficiently kneading the polyamide resin and polyamide resin (D), it is preferably 1 kg / h or less per 1 rpm of screw rotation. Here, the extrusion rate refers to the weight (kg) of the resin composition extruded from the extruder per hour.

[0059] The resin composition thus obtained can be molded by a commonly known method to obtain various molded articles such as sheets, films, etc. Examples of molding methods include injection molding, injection compression molding, extrusion molding, compression molding, blow molding, and press molding.

[0060] Taking advantage of their excellent properties, the resin composition of the present invention and molded articles thereof can be used in a variety of applications, such as automobile parts, gas tank liners, electrical and electronic parts, building materials, various containers, daily necessities, household goods, and sanitary products, etc. In particular, they are particularly preferably used for automobile exterior parts that require toughness and rigidity, as well as electrical and electronic parts such as automobile electrical parts, automobile underhood parts, automobile gear parts, housings, connectors, and reflectors.Specifically, our products include automobile engine peripheral parts such as engine covers, air intake pipes, timing belt covers, intake manifolds, filler caps, throttle bodies, and cooling fans; automobile underhood parts such as cooling fans, radiator tank tops and bases, cylinder head covers, oil pans, brake piping, fuel piping tubes, high-pressure gas tank liners, and exhaust gas system parts; automobile gear parts such as gears, actuators, bearing retainers, bearing cages, chain guides, and chain tensioners; automobile interior parts such as shift lever brackets, steering lock brackets, key cylinders, door inner handles, door handle cowls, interior mirror brackets, air conditioning switches, instrument panels, console boxes, glove boxes, steering wheels, and trim; front fenders, rear fenders, fuel lids, door panels, cylinder head covers, door mirror stays, tailgate panels, license garnishes, roof rails, etc. Suitable examples of the materials for use in the manufacturing of automobiles include automotive exterior parts such as engine mount brackets, rear garnishes, rear spoilers, trunk lids, rocker moldings, moldings, lamp housings, front grilles, mudguards, and side bumpers; intake and exhaust system parts such as air intake manifolds, intercooler inlets, exhaust pipe covers, inner bushings, bearing retainers, engine mounts, engine head covers, resonators, and throttle bodies; engine coolant system parts such as chain covers, thermostat housings, outlet pipes, radiator tanks, oil inators, and delivery pipes; automotive electrical parts such as connectors, wire harness connectors, motor parts, lamp sockets, sensor-mounted switches, and combination switches; and electrical and electronic parts such as SMT-compatible connectors, sockets, card connectors, jacks, power supply parts, switches, sensors, capacitor base plates, relays, resistors, fuse holders, coil bobbins, housings for ICs and LEDs, and reflectors. [Example]

[0061] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The following raw materials were used to obtain the resin compositions of the examples.

[0062] <Compound containing at least one selected from alkali metals and alkaline earth metals> (A-1) Sodium t-butoxide (Tokyo Chemical Industry Co., Ltd.)

[0063] <Polymerization cocatalyst: cyclic molecule> (b1-1) α-cyclodextrin (Tokyo Chemical Industry Co., Ltd.), molecular weight 973 g / mol (b1-2) β-cyclodextrin (Tokyo Chemical Industry Co., Ltd.), molecular weight 1,135 g / mol (b1-3) Polyrotaxane (Advanced Soft Materials Co., Ltd., "Cellum" (registered trademark) Super Polymer SH1300P), number average molecular weight 180,000 g / mol

[0064] <Polymerization cocatalyst: coupling agent> (b2-1) Hexamethylene diisocyanate (Tokyo Chemical Industry Co., Ltd.) (b2-2) 3-Isocyanatepropyltriethoxysilane (Silane coupling agent KBE-9007N manufactured by Shin-Etsu Chemical Co., Ltd.)

[0065] <Polymerization cocatalyst: 5- to 20-membered cyclic lactam> (b3-1) ε-caprolactam (Tokyo Chemical Industry Co., Ltd.)

[0066] <Cyclic Monomers Having Amide Bonds> (C-1) ε-caprolactam (Tokyo Chemical Industry Co., Ltd.)

[0067] <Polyamide> (D-1): Nylon 6 resin ("Amilan" (registered trademark) manufactured by Toray Industries, Inc.), η r =2.70, melting point 225℃

[0068] Here, the relative viscosity η rwas measured in a 0.01 g / ml solution of 98% concentrated sulfuric acid at 25°C. The melting point was determined using a differential scanning calorimeter by lowering the temperature of the polyamide from a molten state to 30°C at a rate of 20°C / min in an inert gas atmosphere, and then heating it to the melting point + 40°C at a rate of 20°C / min.

[0069] <Structural analysis of reaction products> The structural analysis of the reaction product was carried out using the nuclear magnetic resonance (NMR) spectrometer shown below under the following conditions. Equipment: JEOL Ltd. AL-400 Deuterated solvents: deuterated water, deuterated dimethyl sulfoxide, deuterated trifluoroacetic acid Sample concentration: 5 mg sample / 1 mL deuterated solvent.

[0070] <Measurement of amino group concentration in polyamide resin> The amino group concentration of the polyamide resin was determined by titration. An oven-dried polyamide resin was dried at 80°C for more than 10 hours to prepare an oven-dried sample. 1.0 g of the oven-dried sample was dissolved in 50 ml of a phenol / methanol (9:1) solution and titrated with 0.01 mol / L hydrochloric acid.

[0071] <Checking the color tone of polyamide resin when heated> The polyamide resin was heated on a hot stage at 80°C for 30 minutes, and the change in color tone was visually confirmed.

[0072] Example 1 0.4 g of hexamethylene diisocyanate was added to 0.3 g of ε-caprolactam and the mixture was allowed to react at 180°C for 5 minutes. The above reaction mixture was then added to a solution of 0.2 g of α-cyclodextrin dissolved in 10 g of acetone and the mixture was allowed to react at 50°C for 10 minutes. The acetone was then removed, and 60 g of ε-caprolactam was added. The mixture was heated at 180°C for 5 minutes to obtain a mixture of the polymerization cocatalyst and ε-caprolactam. NMR analysis revealed that the polymerization cocatalyst contained 40 mol% of a compound in which hexamethylene diisocyanate, α-cyclodextrin, and ε-caprolactam were combined, and 60 mol% of a compound in which hexamethylene diisocyanate and two ε-caprolactams were combined.

[0073] The reaction mixture was placed in a test tube, 0.5 g of sodium t-butoxide was added, and the mixture was heated and stirred at a polymerization temperature of 180°C for 30 minutes. Stirring was continued until the torque applied to the stirrer began to increase, at which point stirring was stopped and heating was continued. After 30 minutes, the mixture was immediately air-cooled to obtain a polyamide resin.

[0074] The amino group concentration of polyamide resin is 8.9 x 10 -7 mol / g, and the sample was white after heating.

[0075] Example 2 0.4 g of 3-isocyanatepropyltriethoxysilane was added to 60 g of ε-caprolactam and reacted for 5 minutes at 180°C. Then, 0.2 g of α-cyclodextrin was added to the reaction mixture, and the mixture was heated at 180°C for 10 minutes to obtain a mixture of the polymerization cocatalyst and ε-caprolactam.

[0076] The reaction mixture was placed in a test tube, 0.5 g of sodium t-butoxide was added, and the mixture was heated and stirred at a polymerization temperature of 180°C for 30 minutes. Stirring was continued until the torque applied to the stirrer began to increase, at which point stirring was stopped and heating was continued. After 30 minutes, the mixture was immediately air-cooled to obtain a polyamide resin.

[0077] The amino group concentration of polyamide resin is 2.1 x 10-6 mol / g, and the sample was white after heating.

[0078] Example 3 0.4 g of 3-isocyanatepropyltriethoxysilane was added to 60 g of ε-caprolactam and reacted for 5 minutes at 180°C. Then, 0.2 g of β-cyclodextrin was added to the reaction mixture, and the mixture was heated at 180°C for 10 minutes to obtain a mixture of the polymerization cocatalyst and ε-caprolactam.

[0079] The reaction mixture was placed in a test tube, 0.5 g of sodium t-butoxide was added, and the mixture was heated and stirred at a polymerization temperature of 180°C for 30 minutes. Stirring was continued until the torque applied to the stirrer began to increase, at which point stirring was stopped and heating was continued. After 30 minutes, the mixture was immediately air-cooled to obtain a polyamide resin.

[0080] The amino group concentration of polyamide resin is 1.3 x 10 -6 mol / g, and the sample was white after heating.

[0081] Example 4 0.4 g of 3-isocyanatepropyltriethoxysilane was added to 60 g of ε-caprolactam and reacted for 5 minutes at 180°C. 0.2 g of polyrotaxane was then added to the reaction mixture and heated at 180°C for 10 minutes to obtain a mixture of the polymerization cocatalyst and ε-caprolactam.

[0082] The reaction mixture was placed in a test tube, 0.5 g of sodium t-butoxide was added, and the mixture was heated and stirred at a polymerization temperature of 180°C for 30 minutes. Stirring was continued until the torque applied to the stirrer began to increase, at which point stirring was stopped and heating was continued. After 30 minutes, the mixture was immediately air-cooled to obtain a polyamide resin.

[0083] The amino group concentration of polyamide resin is 5.1 x 10 -7 mol / g, and the sample was white after heating.

[0084] (Comparative Example 1) <Cyclodextrin tosylation> 4.4 g of β-cyclodextrin was dispersed in 40 mL of pyridine and cooled in an ice bath. 8.8 g of paratoluenesulfonyl chloride was then added, and the mixture was allowed to react in an ice bath for 6 hours. The reaction mixture was then added to 300 mL of deionized water to precipitate a solid, which was then collected using a glass filter. The resulting solid was washed with a large amount of deionized water and diethyl ether and then vacuum-dried to obtain tosylated β-cyclodextrin (referred to as "tosylated β-cyclodextrin"). The tosylation of β-cyclodextrin was confirmed by structural analysis using NMR.

[0085] <Amination of cyclodextrin> 6.65 g of the tosylated β-cyclodextrin obtained above was dissolved in 35 mL of dimethylformamide and added dropwise over 20 minutes using a dropping funnel to 100 mL of 1,2-ethylenediamine heated to 70°C. The reaction was then allowed to proceed for an additional 3 hours, and the reaction solution was poured into 1 L of chloroform to precipitate a solid. The solid was collected by suction filtration, washed with chloroform, and vacuum dried to obtain aminated β-cyclodextrin (referred to as "aminated β-cyclodextrin"). The amination of the β-cyclodextrin was confirmed by structural analysis using NMR.

[0086] <Polycaprolactamization of cyclodextrin> 10.0 g of ε-caprolactam was dissolved by heating at 150°C under a nitrogen flow, and 0.5 g of the above-mentioned aminated β-cyclodextrin and a solution of 0.3 g of tin octoate in 0.8 g of toluene were added. The mixture was then gradually heated to 210°C and reacted at 210°C for 1 hour. 20 mL of 3% phosphoric acid in methanol was added to the resulting reaction mixture, which was stirred for 5 minutes. The solid was then poured into ion-exchanged water to precipitate, followed by vacuum drying to obtain the desired polyamide-modified cyclodextrin bearing lactam-derived modifying groups. NMR structural analysis confirmed the formation of polyamide-modified cyclodextrin.

[0087] The amino group concentration of the polyamide-modified cyclodextrin was 3.7 × 10 -4 mol / g, and the sample was yellow after heating.

[0088] (Comparative Example 2) <Tosylation of polyrotaxane> 1 g of polyrotaxane prepared by the method of Synthesis Example 1 was dispersed in 30 mL of pyridine and cooled in an ice bath. 2.0 g of paratoluenesulfonyl chloride was then added, and the mixture was allowed to react in an ice bath for 6 hours. The reaction solution was then poured into 500 mL of deionized water to precipitate the solid, which was then collected using a glass filter. The resulting solid was washed with a large amount of deionized water and diethyl ether and then vacuum-dried to obtain a tosylated polyrotaxane. The tosylation of the polyrotaxane was analyzed by NMR for structural analysis.

[0089] <Amination of tosylated polyrotaxane> 1 g of the synthesized tosylated polyrotaxane was dissolved in 30 mL of dimethylformamide. This solution was added dropwise to a mixture of 40 mL of ethylenediamine and 20 mL of dimethylformamide preheated to 70°C. The reaction was allowed to proceed for 5 hours at 70°C. The reaction mixture was then poured into 1 L of diethyl ether to precipitate the solids, which were then collected by centrifugation. The solids were then dissolved in dimethylformamide and purified by reprecipitation in diethyl ether. The resulting solids were then dried to obtain aminated polyrotaxane. The amination of the polyrotaxane was analyzed by NMR for structural analysis.

[0090] <Polycaprolactamization of aminated polyrotaxane> 6.8 g of ε-caprolactam was heated to 150 °C under a nitrogen flow and dissolved. 0.2 g of the above-mentioned aminated polyrotaxane and a solution of 0.3 g of tin octoate in 0.8 g of toluene were added. The temperature was then gradually increased to 190 °C, and the reaction was carried out at 190 °C for 1 hour. The resulting reaction mixture was poured into 200 mL of methanol to precipitate the solid, which was then dried in vacuo to obtain the desired modified polyrotaxane bearing lactam-derived modifying groups. The structure of the modified polyrotaxane was analyzed by NMR.

[0091] The amino group concentration of the polyamide-modified polyrotaxane was 5.2 × 10 -4 mol / g, and the sample was yellow after heating.

[0092] The polyamide resins (Comparative Examples 1 and 2) produced by the methods shown in Patent Documents 5 and 6 have a high amino group concentration and turn yellow after heating at 80°C for 30 minutes, whereas the polyamide resins (Examples 1 to 4) produced by the method of the present invention have a low amino group concentration and do not turn yellow even after heating, demonstrating high heat resistance.

Claims

1. A method for producing a polyamide resin by polymerizing a cyclic monomer (C) having an amide bond in the presence of a compound (A) containing at least one selected from an alkali metal and an alkaline earth metal, and a polymerization co-catalyst (B), wherein the polymerization co-catalyst (B) contains a derivative of a cyclic molecule having a molecular weight of at least 300 g / mol.

2. The method for producing a polyamide resin according to claim 1, wherein the polymerization co-catalyst (B) has a structure represented by the following formula (I): 【Chemical 1】 (n is an integer from 3 to 18.)

3. The method for producing a polyamide resin according to claim 2, wherein the polymerization co-catalyst (B) is obtained by reacting a cyclic molecule having a molecular weight of at least 300 g / mol or more, a 5- to 20-membered cyclic lactam, and a coupling agent having at least one isocyanate group.

4. 4. The method for producing a polyamide resin according to claim 3, wherein the coupling agent having at least one isocyanate group is any one selected from the group consisting of a diisocyanate compound and a silane coupling agent having one isocyanate group.

5. The method for producing a polyamide resin according to any one of claims 1 to 4, wherein the polymerization co-catalyst (B) is a derivative of cyclodextrin.

6. The method for producing a polyamide resin according to claim 1, wherein the cyclic monomer (C) having an amide bond is a 5- to 20-membered cyclic lactam.

7. The method for producing a polyamide resin according to claim 6, wherein the cyclic monomer (C) having an amide bond is ε-caprolactam.

8. A polyamide resin having a cyclic structure derived from a derivative of a cyclic molecule having a molecular weight of 300 g / mol or more, and a terminal amino group concentration of 5.0×10 －５ mol / g or less.

9. The polyamide resin according to claim 8 , wherein the cyclic structure is derived from a derivative of cyclodextrin.

10. The polyamide resin according to claim 8, wherein the polyamide resin contains a structure derived from a 5- to 20-membered cyclic lactam.

11. The polyamide resin according to claim 10, wherein the polyamide resin contains a structure derived from ε-caprolactam.

12. A polyamide resin composition comprising at least the polyamide resin according to any one of claims 8 to 11 and a polyamide resin (D).

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