Cyclic polyamide resin, method for producing the same, and cyclic polyamide resin solution

Abstract

This invention provides a method for producing a cyclic polyamide resin that has excellent mechanical strength, is easily soluble in various organic solvents, and is useful as a material for coatings and adhesives. [Solution] A method for producing a cyclic polyamide resin comprising: (1) reacting a mixture containing 20-44 mol% itaconic acid, 20-44 mol% diamine having an alkylene group with 4-36 carbon atoms, and 12-60 mol% aminoalkylcarboxylic acid having an alkylene group with 3-12 carbon atoms (provided that the total of itaconic acid, diamine, and aminoalkylcarboxylic acid is 100 mol%) to obtain a reaction product; and (2) cyclizing and polymerizing the reaction product to obtain a cyclic polyamide resin containing a structure represented by the following formula (1). TIFF2026053849000007.tif28170 (In formula (1), "*" indicates the bonding position with other structures)

Description

Technical Field

[0001] The present invention relates to a cyclic polyamide resin, a method for producing the cyclic polyamide resin, and a cyclic polyamide resin solution.

Background Art

[0002] By forming a coating film, the polyamide resin can impart properties such as abrasion resistance, friction resistance, oil resistance, solvent resistance, chemical resistance, gas barrier property, and adhesiveness to various substrates. Therefore, the polyamide resin is widely used in coating agents, adhesives, fiber treatment agents, fiber sealants, glass fiber bundling agents, paper treatment agents, binders, lubricants, steel plate surface treatment agents, surface modifiers, water-based inks, and hot melt adhesives such as core adhesives.

[0003] In recent years, polyamide resins having a high glass transition temperature and exhibiting performance as engineering plastics have been developed. For example, a polyamide resin obtained by reacting itaconic acid with an aliphatic alkylene diamine or an aromatic diamine and subjecting them to dehydration condensation has been proposed (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the polyamide resin proposed in Patent Document 1 has low solubility in hydrocarbon solvents and ester solvents, similar to general-purpose polyamides, and cannot necessarily be said to be a suitable material for applications such as coating agents and adhesives.

[0006] This invention has been made in view of the problems of the prior art, and its objective is to provide a cyclic polyamide resin that has excellent mechanical strength, is easily soluble in various organic solvents, and is useful as a material for coatings and adhesives, as well as a method for producing the same. Another objective of this invention is to provide a cyclic polyamide resin solution using the above-mentioned cyclic polyamide resin. [Means for solving the problem]

[0007] In other words, the present invention provides a method for producing the following cyclic polyamide resin. [1] A method for producing a cyclic polyamide resin, comprising the steps of: (1) reacting a mixture containing 20-44 mol% itaconic acid, 20-44 mol% diamine having an alkylene group having 4-36 carbon atoms, and 12-60 mol% aminoalkylcarboxylic acid having an alkylene group having 3-12 carbon atoms (where the total of the itaconic acid, the diamine, and the aminoalkylcarboxylic acid is 100 mol%) to obtain a reaction product; and (2) cyclizing and polymerizing the reaction product to obtain a cyclic polyamide resin having a structure represented by the following formula (1).

[0008] TIFF2026053849000001.tif28170 (In formula (1) above, "*" indicates the bonding position with other structures)

[0009] [2] A method for producing a cyclic polyamide resin according to [1], wherein the proportion of the structure represented by formula (1) in the cyclic polyamide resin is 25 to 81.1 mol%. [3] The method for producing a cyclic polyamide resin according to [1] or [2], wherein the aminoalkylcarboxylic acid is at least one selected from the group consisting of 4-aminobutanoic acid, 6-aminohexanoic acid, and 11-aminoundecanoic acid. [4] A method for producing a cyclic polyamide resin according to any one of [1] to [3], wherein the diamine is at least one selected from the group consisting of 1,5-pentanediamine, 1,6-hexanediamine, 1,10-decanediamine, 1,12-dodecanediamine, and dimeramine. [5] A method for producing a cyclic polyamide resin according to any one of [1] to [4] above, wherein the itaconic acid, the diamine, and the aminoalkylcarboxylic acid are all compounds derived from biological resources.

[0010] Furthermore, the present invention provides the following cyclic polyamide resins. [6] A cyclic polyamide resin manufactured by any of the manufacturing methods described in [1] to [5] above. [7] The cyclic polyamide resin according to [6], wherein the relative viscosity of a 0.01 g / mL solution in m-cresol as a solvent is 1.8 to 4.5 at 25°C.

[0011] Furthermore, the present invention provides the following cyclic polyamide resin solutions. [8] A cyclic polyamide resin solution containing the cyclic polyamide resin described in [6] or [7] above, and an organic solvent for dissolving the cyclic polyamide resin. [9] The cyclic polyamide resin solution according to [8], wherein the organic solvent is at least one selected from the group consisting of toluene, n-propanol, isopropanol, methyl ethyl ketone, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a cyclic polyamide resin that has excellent mechanical strength, is easily soluble in various organic solvents, and is useful as a material for coatings and adhesives, as well as a method for producing the same. Furthermore, according to the present invention, it is possible to provide a cyclic polyamide resin solution using the above-mentioned cyclic polyamide resin. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the 1H-NMR measurement results of the cyclic polyamide resin produced in Example 1. [Figure 2] This figure shows the measurement results of the infrared absorption spectrum of the cyclic polyamide resin produced in Example 1. [Modes for carrying out the invention]

[0014] <Cyclic polyamide resin and method for producing the same> The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. One embodiment of the method for producing the cyclic polyamide resin of the present invention comprises the steps of (1) reacting a mixture containing itaconic acid, a diamine having an alkylene group having 4 to 36 carbon atoms, and an aminoalkylcarboxylic acid having an alkylene group having 3 to 12 carbon atoms to obtain a reaction product, and (2) cyclizing and polymerizing the reaction product to obtain a cyclic polyamide resin having a structure represented by the following formula (1). Furthermore, one embodiment of the cyclic polyamide resin of the present invention is produced by the above method. The details of the cyclic polyamide resin of the present invention and the method for producing the same will be described below.

[0015] TIFF2026053849000002.tif28170 (In formula (1) above, "*" indicates the bonding position with other structures)

[0016] (Monomers) In the manufacturing method of this embodiment, a polyamide resin having a cyclic structure is produced using a dicarboxylic acid, a diamine, and an aminoalkylcarboxylic acid. Itaconic acid is used as the dicarboxylic acid. The compound represented by the following general formula (1-1) is used as the diamine. The compound represented by the following general formula (1-2) is used as the aminoalkyldicarboxylic acid. H2N-R1-NH2···(1-1) HOOC-R2-NH2···(1-2) (In general formula (1-1), R1 represents an alkylene group having 4 to 36 carbon atoms.) (In the general formula (1-2), R2 represents an alkylene group having 3 to 12 carbon atoms)

[0017] Itaconic acid may be produced using a fungus such as Aspergillus terreus, or may be synthesized using petroleum as a raw material. Among them, itaconic acid produced using a fungus such as Aspergillus terreus is a compound derived from biological resources (biomass), and thus has the advantage of being more environmentally friendly than itaconic acid synthesized using petroleum as a raw material.

[0018] The diamine has an alkylene group having 4 to 36 carbon atoms. This alkylene group may be linear or branched. Further, the alkylene group may be a structure derived from dimer acid. By using a diamine having an alkylene group having 4 to 36 carbon atoms, appropriate water resistance, solvent solubility, and mechanical properties can be imparted to the resulting cyclic polyamide resin.

[0019] Examples of diamines include 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine, 1,16-hexadecanediamine, and 1,17-heptadecanediamine. Examples include 1,18-octadecanediamine, 1,19-nonadecanediamine, 1,20-eicosanediamine, 2-methyl-1,5-pentamethylenediamine, 3-methyl-1,5-pentamethylenediamine, 2-methyl-1,8-octanediamine, 2,2,4-trimethyl-1,6-hexamethylenediamine, 2,4,4-trimethyl-1,6-hexamethylenediamine, 5-methyl-1,9-nonanediamine, and dimer amines. In particular, it is preferable to use at least one diamine selected from the group consisting of 1,5-pentanediamine, 1,6-hexanediamine, 1,10-decanediamine, 1,12-dodecanediamine, and dimer amines. Furthermore, in terms of being able to use biomass-derived compounds, it is even more preferable to use a diamine selected from the group consisting of 1,5-pentanediamine, 1,10-decanediamine, and dimeramine.

[0020] Aminoalkylcarboxylic acids have an alkylene group having 3 to 12 carbon atoms. This alkylene group may be linear or branched. By using an aminoalkylcarboxylic acid having an alkylene group having 3 to 12 carbon atoms, mechanical properties can be imparted to the resulting cyclic polyamide resin.

[0021] Examples of aminoalkylcarboxylic acids include 4-aminobutanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminolauric acid. From the viewpoint of obtaining a cyclic polyamide resin that balances solvent solubility and mechanical properties, it is preferable that the aminoalkylcarboxylic acid is at least one selected from the group consisting of 4-aminobutanoic acid, 6-aminohexanoic acid, and 11-aminoundecanoic acid. Furthermore, from the viewpoint of consideration for the global environment, it is preferable that itaconic acid, diamine, and aminoalkylcarboxylic acid are all compounds derived from biological resources.

[0022] Further amino group-containing compounds other than diamines and aminoalkylcarboxylic acids may be used. Examples of amino group-containing compounds include aromatic diamines such as phenylenediamine and xylylenediamine.

[0023] (Process (1)) In step (1), a mixture containing itaconic acid, diamine, and aminoalkylcarboxylic acid is reacted to obtain a reaction product. The mixture contains 20-44 mol% itaconic acid, 20-44 mol% diamine, and 12-60 mol% aminoalkylcarboxylic acid. However, the total of itaconic acid, diamine, and aminoalkylcarboxylic acid is 100 mol%. By using a mixture in which the content of each component is within the above range, a cyclic polyamide resin with excellent solvent solubility and mechanical properties can be obtained, in which the structure represented by formula (1) (oxopyrrolidine skeleton) is introduced in a predetermined proportion.

[0024] A mixture containing itaconic acid, a diamine, and an aminoalkylcarboxylic acid may further contain an organic solvent. Preferably, the organic solvent is one that dissolves the itaconic acid, diamine, and aminoalkylcarboxylic acid at a temperature range of, for example, 20 to 90°C, while being insoluble or substantially insoluble in the resulting reaction product (salt). Examples of organic solvents include aliphatic alcohols such as methanol, ethanol, propanol, and butanol; ketone compounds such as acetone and methyl ethyl ketone; ethyl acetate; butyl acetate; and tetrahydrofuran. Among these, lower alcohols such as ethanol are preferred. The amount of organic solvent in the mixture is preferably about 1 to 20 times the total mass of the itaconic acid, diamine, and aminoalkylcarboxylic acid, and more preferably about 3 to 15 times the total mass.

[0025] From the viewpoint of increasing reaction efficiency, it is preferable to react a mixture containing itaconic acid, a diamine, and an aminoalkylcarboxylic acid under temperature conditions of 20 to 90°C. By reacting the mixture, a reaction product containing a salt produced by the ionization reaction between the carboxyl group of itaconic acid and the amino group of the diamine or aminoalkylcarboxylic acid can be obtained. The reaction time varies depending on the amount of organic solvent and the reaction temperature, and cannot be determined in general terms, but it is usually sufficient to take about 1 to 6 hours. The atmosphere during the reaction may be air, or an inert gas atmosphere such as nitrogen gas or argon gas.

[0026] After the reaction, the reaction product can be recovered by crystallization. Methods for crystallizing the reaction product include, for example, cooling the reaction mixture to a temperature of about 0 to 25°C; adding poor solvents such as hexane, toluene, xylene, and ethyl acetate dropwise to the reaction mixture; and evaporating the organic solvent contained in the reaction mixture.

[0027] The crystallized reaction product can be recovered by methods such as filtration. The recovered reaction product may be washed with an organic solvent at approximately 0-25°C as needed. Alternatively, the recovered reaction product may be dried by vacuum drying or other methods.

[0028] (Process (2)) In step (2), the reaction product obtained in step (1) is subjected to cyclization and polymerization. This yields a cyclic polyamide resin containing the structure represented by formula (1). Methods for polymerization of the reaction product (polymerization method) include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among these, bulk polymerization is preferred from the viewpoint of efficiently preparing a cyclic polyamide resin with a low amount of impurities.

[0029] The temperature at which the reaction products are cyclized and polymerized is preferably above the glass transition temperature of the cyclic polyamide resin produced, and below the temperature at which the cyclic polyamide resin does not thermally decompose. Specifically, the temperature at which the reaction products are cyclized and polymerized is preferably 150 to 250°C.

[0030] From the viewpoint of improving the molecular weight of the resulting cyclic polyamide resin, polymerization is preferably carried out under atmospheric pressure and nitrogen gas or under reduced pressure as needed. When polymerization is carried out under reduced pressure, the final target pressure is preferably 760 to 0.1 Torr. The polymerization time is preferably 2 to 24 hours. Components generated as polymerization progresses (water, alcohol, etc.) are preferably recovered by cooling and condensing them in a water-cooled condenser, considering cost and environmental factors.

[0031] From the viewpoint of efficiently producing cyclic polyamide resins, it is preferable to use an appropriate amount of catalyst during the polymerization reaction. Examples of catalysts include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, ethyl phosphate, and triphenyl phosphite. Among these, sodium dihydrogen phosphate, disodium hydrogen phosphate, and trisodium phosphate are preferred, and sodium dihydrogen phosphate is even more preferred.

[0032] The obtained cyclic polyamide resin may be dissolved in a solvent such as N,N-dimethylformamide as needed, and then purified by precipitation using a hydrocarbon solvent such as hexane. Alternatively, the obtained cyclic polyamide resin may be dried by vacuum drying or other methods.

[0033] Because cyclic polyamide resins contain the structure represented by formula (1) (oxopyrrolidine skeleton), they are readily soluble in various organic solvents and also exhibit excellent mechanical properties such as tensile strength. The proportion of the structure represented by formula (1) in the cyclic polyamide resin is preferably 25 to 81.1 mol%, more preferably 40 to 75 mol%, and particularly preferably 50 to 70 mol%. By having the proportion of the structure represented by formula (1) (oxopyrrolidine skeleton) within the above range, the solvent solubility and mechanical properties of the cyclic polyamide resin are further improved. In cyclic polyamide resins, the oxopyrrolidine skeleton is usually randomly present. However, the oxopyrrolidine skeleton may be present alternately in the cyclic polyamide resin or in a block-like structure.

[0034] The oxopyrrolidine skeleton is formed by the dehydration Michael addition of 1 mole of the amino group of a diamine or aminoalkyl carboxylic acid to 1 mole of itaconic acid. For example, when reacting itaconic acid / diamine / aminoalkyl carboxylic acid in a ratio of 20 / 20 / 60 moles, 20 moles of a compound containing the oxopyrrolidine skeleton are produced. The ratio of the compound containing the oxopyrrolidine skeleton to the unreacted starting material is then 20 / 80 moles, and the proportion of the oxopyrrolidine skeleton is calculated to be (20 / 80) × 100 = 25 mol%.

[0035] As shown in the following reaction equation, when a mixture containing itaconic acid (2), diamine (3), and aminoalkylcarboxylic acid (4) is reacted, for example, a neutralization salt (5) of itaconic acid (2) and diamine (3) is formed. Then, upon heating, dehydration condensation and Michael cycloaddition reactions proceed, forming a compound (6) with an oxopyrrolidine skeleton. Subsequently, it is thought that the compound (6) with the oxopyrrolidine skeleton and the aminoalkylcarboxylic acid (4) undergo dehydration condensation (polymerization) to form a cyclic polyamide resin (7).

[0036] TIFF2026053849000003.tif122170

[0037] Theoretically, the reaction proceeds as shown in the above reaction equation to form a cyclic polyamide resin. However, in practice, the reaction does not proceed only as shown in the above reaction equation, and various side reactions occur, and the cyclic polyamide resin can also be obtained in the form of a so-called composition (resin composition) containing multiple components. For example, in step (1), it is thought that not only the neutralized salt (5) of itaconic acid (2) and diamine (3), but also the neutralized salt of itaconic acid (2) and aminoalkylcarboxylic acid (4), and the neutralized salt of 2 mol of itaconic acid (2) and 1 mol of diamine (3) are formed. Then, in step (2), when the cyclization and polymerization reactions are carried out in the presence of these multiple types of neutralized salts, multiple resins and by-products having structures other than the structure represented by formula (7) above are formed. As a result, the cyclic polyamide resin of this embodiment can be obtained in the form of a resin composition containing a resin having the structure represented by formula (7) above. Thus, it is difficult or practically impossible to identify the structure and composition ratio of the components in the cyclic polyamide resin of this embodiment by analysis or other means.

[0038] The relative viscosity of a 0.01 g / mL solution of cyclic polyamide resin in m-cresol at 25°C is preferably 1.8 to 4.5. Using a cyclic polyamide resin with a relative viscosity of 1.8 or higher can further improve the mechanical properties of the resulting molded article. Furthermore, if the relative viscosity of the cyclic polyamide resin is 4.5 or lower, the fluidity of the cyclic polyamide resin solution can be further improved.

[0039] The cyclic polyamide resin of this embodiment is thermoplastic and can therefore be used as a molten product after heating and melting. In other words, the cyclic polyamide resin of this embodiment is suitable as a molding material for producing various molded bodies such as films and plates by molding methods such as injection molding. Furthermore, a resin composition containing the cyclic polyamide resin of this embodiment and fibers can be used as a molding material to produce molded bodies using a three-dimensional (3D) printer.

[0040] <Cyclic polyamide resin solution> As described above, the cyclic polyamide resin of this embodiment is readily soluble in various organic solvents and is a suitable resin for applications such as coatings and adhesives. Therefore, a cyclic polyamide resin solution can be obtained by dissolving the cyclic polyamide resin of this embodiment in an organic solvent. That is, one embodiment of the cyclic polyamide resin solution of the present invention contains the aforementioned cyclic polyamide resin and an organic solvent for dissolving this cyclic polyamide resin.

[0041] Conventional polyamide resins are widely used as coating materials for various substrates due to their excellent heat resistance, chemical resistance, and solvent resistance. However, conventional polyamide resins dissolve only in high-boiling-point, highly hygroscopic polar organic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), and γ-butyrolactone (GBL). This requires special environmental preparation and high-temperature heating to volatilize the organic solvents. As a result, there have been challenges such as limitations on processing equipment and substrates, and high costs.

[0042] In contrast, the aforementioned cyclic polyamide resin can be dissolved in polar organic solvents that have high boiling points and high hygroscopicity, thus eliminating the need for special processing equipment or substrates, and allowing for the creation of cyclic polyamide resin solutions dissolved in various organic solvents.

[0043] Non-amide organic solvents can be used as the organic solvent. Preferably, at least one selected from the group consisting of toluene, n-propanol, isopropanol, methyl ethyl ketone, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate is used as the organic solvent. In other words, it is possible to dissolve the cyclic polyamide resin without substantially using high-boiling-point, highly humid polar organic solvents such as NMP, DMAC, and GBL. As a result, a cyclic polyamide resin solution can be obtained that has excellent drying properties, workability, and productivity, while retaining the heat resistance, mechanical properties, chemical resistance, and various other properties inherent to the cyclic polyamide resin.

[0044] The content of cyclic polyamide resin in the cyclic polyamide resin solution is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and particularly preferably 15 to 40% by mass, from the viewpoint of workability and solubility.

[0045] The cyclic polyamide resin and cyclic polyamide solution of this embodiment may contain various additives depending on the application. Examples of additives include colorants such as pigments and dyes, ultraviolet absorbers, ultraviolet stabilizers, antioxidants, rust inhibitors, antibacterial agents, plasticizers, anti-algal agents, antifungal agents, flame retardants, and foaming agents. The amount of additives can be appropriately determined depending on the type of additive. [Examples]

[0046] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0047] <Manufacturing of cyclic polyamide resins> (Example 1) Ten moles of itaconic acid, ten moles of hexamethylenediamine (1,6-hexanediamine), and five moles of 11-aminoundecanoic acid were mixed and then dissolved in 2,000 ml of ethanol to obtain a mixture. The resulting mixture was heated to 60°C with stirring and reacted for 4 hours, then cooled to 25°C to precipitate a white solid reaction product. The reaction product was recovered by filtration, washed with ethanol at approximately 10°C, and then dried in a vacuum dryer at 40°C for 12 hours.

[0048] 200 g of the obtained reaction product and 2.0 g of sodium dihydrogen phosphate, the catalyst, were mixed and heated to 250°C over 2 hours in a nitrogen gas atmosphere. During the heating process, the removal of water was confirmed at around 150°C. It is presumed that at a temperature of around 150°C, the Michael addition reaction between itaconic acid and the amino group, along with dehydration, proceeded, and a five-membered ring was formed. After reaching 250°C, the reaction atmosphere was reduced under pressure and stirred for 5 hours to carry out the polymerization reaction (dehydration condensation) to obtain a cyclic polyamide resin.

[0049] A sample was prepared by dissolving the obtained cyclic polyamide resin in didimethylformamide. 1 ¹H-NMR was measured. The measurement results are shown in Figure 1. As shown in Figure 1, the disappearance of peaks originating from the protons of the double bond of itaconic acid (5.88 ppm, 6.35 ppm) and the generation of peaks originating from the protons of the five-membered ring (oxopyrrolidine ring) were confirmed. In addition, the infrared absorption spectrum was measured using an infrared spectrophotometer. The measurement results are shown in Figure 2. As shown in Figure 2, the absorption originating from the double bond of itaconic acid (1,620 cm⁻¹) -1 The disappearance of the surrounding area and the generation of absorption originating from the amide bond were confirmed. The structure of the cyclic polyamide resin was then confirmed using the same method. The proportion of the structure represented by formula (1) (oxopyrrolidine skeleton) in the obtained cyclic polyamide resin can be calculated to be 66.7 mol%.

[0050] (Examples 2-8, Comparative Examples 1-4) A cyclic polyamide resin was produced in the same manner as in Example 1 described above, except that the formulation was as shown in Table 1.

[0051] TIFF2026053849000004.tif144170

[0052] <Rating> (Relative viscosity (ηr)) A cyclic polyamide resin was dissolved in m-cresol (reagent grade) to prepare a 0.01 g / mL solution. The viscosity of the prepared solution at 25°C was measured using an Ostwald viscometer, and the relative viscosity was calculated. The results are shown in Table 2.

[0053] (Solubility) 35 g of n-propanol and 35 g of ethyl acetate were placed in a 200 mL beaker, and the temperature was adjusted to 25°C. 30 g of cyclic polyamide resin was added, and the mixture was stirred using a stirrer for 24 hours. After stirring, the presence or absence of insoluble matter was checked, and the solubility of the cyclic polyamide resin was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. ◎: It dissolved completely relatively quickly. ○: Completely dissolved. ×: Insoluble material remained.

[0054] (Tensile strength) Pellets of cyclic polyamide resin were prepared using a twin-screw extruder. The prepared pellets were molded using an injection molding machine to obtain test specimens (ASTM No. 1 dumbbell) for strength measurement. Tensile strength measurements were performed using a precision universal testing machine (product name "Autograph AGX", manufactured by Shimadzu Corporation) at a speed of 50 mm / min, and the tensile strength (MPa) of the test specimens at the yield point was measured. The results are shown in Table 2.

[0055] TIFF2026053849000005.tif41170 [Industrial applicability]

[0056] The cyclic polyamide resin of the present invention is soluble in various solvents and is therefore useful as a material for coatings and adhesives.

Claims

1. Step (1) involves reacting a mixture containing 20-44 mol% itaconic acid, 20-44 mol% diamine having an alkylene group with 4-36 carbon atoms, and 12-60 mol% aminoalkylcarboxylic acid having an alkylene group with 3-12 carbon atoms (where the total of the itaconic acid, the diamine, and the aminoalkylcarboxylic acid is 100 mol%) to obtain a reaction product. A method for producing a cyclic polyamide resin, comprising the steps of: (2) cyclizing and polymerizing the reaction product to obtain a cyclic polyamide resin having a structure represented by the following formula (1). (In formula (1) above, "*" indicates the bonding position with other structures.)

2. A method for producing a cyclic polyamide resin according to claim 1, wherein the proportion of the structure represented by formula (1) in the cyclic polyamide resin is 25 to 81.1 mol%.

3. The method for producing a cyclic polyamide resin according to claim 1, wherein the aminoalkylcarboxylic acid is at least one selected from the group consisting of 4-aminobutanoic acid, 6-aminohexanoic acid, and 11-aminoundecanoic acid.

4. The method for producing a cyclic polyamide resin according to claim 1, wherein the diamine is at least one selected from the group consisting of 1,5-pentanediamine, 1,6-hexanediamine, 1,10-decanediamine, 1,12-dodecanediamine, and dimeramine.

5. A method for producing a cyclic polyamide resin according to claim 1, wherein the itaconic acid, the diamine, and the aminoalkylcarboxylic acid are all compounds derived from biological resources.

6. A cyclic polyamide resin produced by the manufacturing method described in any one of claims 1 to 5.

7. The cyclic polyamide resin according to claim 6, wherein the relative viscosity of a 0.01 g / mL solution in m-cresol as a solvent at 25°C is 1.8 to 4.

5.

8. A cyclic polyamide resin solution containing the cyclic polyamide resin described in claim 6 and an organic solvent for dissolving the cyclic polyamide resin.

9. The cyclic polyamide resin solution according to claim 8, wherein the organic solvent is at least one selected from the group consisting of toluene, n-propanol, isopropanol, methyl ethyl ketone, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate.

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