Method for producing polyamide

Abstract

Provided is a method for producing a polyamide having an excellent appearance after heating. A method for producing a polyamide, comprising: a step of heating a composition comprising a diamine represented by formula (1), a dicarboxylic acid, and a solvent; and a step of removing the solvent during the heating step of the composition, after the heating step, or after the heating step, and an operation of adding a basic compound and / or a base generating agent to the composition during the heating step of the composition and / or before the heating step. In formula (1), X is a heteroatom, and n is an integer of 0 to 5. The portion of the ring containing X represents a cyclic structure containing X.

Description

Technical Field

[0001] The present invention relates to a method for producing polyamide. Background Art

[0002] The problems of global warming and depletion of petroleum resources are becoming increasingly serious. From the perspective of protecting the global environment, the use of biomass plastics has attracted much attention. As biomass plastics, polylactic acid, polybutylene succinate, and recently bio-polyethylene have been developed. However, the melting point of these biomass plastics is less than 180°C and their heat resistance is poor. As a method of improving the heat resistance of plastics, the use of aromatic monomers and alicyclic monomers is effective, but the types of aromatic monomers and alicyclic monomers derived from biomass are limited. Among them, in recent years, polyamides using 2,5-bis(aminomethyl)tetrahydrofuran obtained from biomass have been studied (Non-Patent Literature 1).

[0003] Prior art literature

[0004] Non-patent literature

[0005] Non-Patent Literature 1: New Developments in Wood Chemistry, CMC Publishing Co., Ltd., 1st edition published on August 31, 2007 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, the properties and improvements of polyamides using 2,5-bis(aminomethyl)tetrahydrofuran as a raw material diamine have not been fully studied. In particular, the present inventors have conducted studies and found that polyamides using 2,5-bis(aminomethyl)tetrahydrofuran as a raw material diamine have a time difference in appearance after heating.

[0008] An object of the present invention is to solve the above problems, and an object of the present invention is to provide a method for producing a polyamide having an excellent appearance after heating.

[0009] Solutions for solving problems

[0010] Based on the above problems, the present inventors have conducted studies and found that the above problems can be solved by allowing a basic compound to be present during the polycondensation reaction of a diamine such as 2,5-bis(aminomethyl)tetrahydrofuran and a dicarboxylic acid.

[0011] Specifically, the above-mentioned problems were solved by the following means.

[0012] <1> A method for producing polyamide, comprising:

[0013] a step of heating a composition comprising a diamine represented by formula (1), a dicarboxylic acid, and a solvent; and

[0014] a step of removing the solvent during or after the heating step of the composition,

[0015] The step of heating the composition and / or before the heating step may include adding a basic compound and / or a base generating agent to the composition.

[0016] Formula (1)

[0017]

[0018] (In formula (1), X is a heteroatom, and n is an integer of 0 to 5. The portion of the ring containing X represents a cyclic structure containing X.)

[0019] <2> according to <1> The method for producing polyamide comprises adding the basic compound and / or the base generating agent to the composition in the heating step of the composition.

[0020] <3> according to <1> or <2> The method for producing a polyamide, wherein the diamine represented by the formula (1) includes a diamine represented by the formula (2).

[0021] Formula (2)

[0022]

[0023] (In formula (2), n is an integer from 0 to 5.)

[0024] <4> according to <1> or <2> The method for producing a polyamide, wherein the diamine represented by the formula (1) contains 2,5-bis(aminomethyl)tetrahydrofuran.

[0025] <5> according to <1> ~ <4> The method for producing a polyamide according to any one of the preceding claims, wherein the molar ratio of diamine to dicarboxylic acid contained in the composition is 0.8<diamine / dicarboxylic acid<1.2

[0026] <6> according to <1> ~ <5> The method for producing a polyamide as described in any one of the above, comprising the step of adding the basic compound to the composition.

[0027] <7> according to <1> ~ <6> The method for producing a polyamide according to any one of the above, wherein the basic compound and the basic compound generated by the base generator each contain at least one selected from ammonia, an organic amine, a salt of ammonia and a weak acid, and a metal salt of a weak acid.

[0028] <8> according to <7> In the method for producing polyamide, the basic compound and the basic compound generated by the base generator each contain at least one selected from ammonia and a metal salt of a weak acid.

[0029] <9> according to <1> ~ <8> The method for producing a polyamide according to any one of the preceding claims, wherein the pH of the solution when the basic compound and the basic compound generated by the base generator are dissolved in the solvent contained in the composition at 23°C to a concentration of 0.55 mmol / 40 g of solvent is 7 to 11.

[0030] <10> according to <1> ~ <9> The method for producing a polyamide as described in any one of the above, wherein the total amount of the basic compound and / or the base generating agent is 0.1 to 100 mol relative to 100 mol of the dicarboxylic acid contained in the composition.

[0031] <11> according to <1> ~ <10> The method for producing a polyamide according to any one of the above aspects, wherein the dicarboxylic acid comprises at least one selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, glutaric acid, adipic acid, and sebacic acid.

[0032] <12> according to <1> ~ <11> The method for producing a polyamide according to any one of the preceding claims, further comprising heating under reduced pressure after the step of removing the solvent.

[0033] <13> according to <1> ~ <12> The method for producing a polyamide as described in any one of the preceding claims, wherein in the aforementioned composition, the value obtained by subtracting the pH of the aforementioned basic compound and the basic compound generated by the aforementioned base generator from the pH of the diamine represented by the formula (1) is 0.1 or more and 5 or less, and the aforementioned pH is the pH of a solution when the aforementioned basic compound, the basic compound generated by the aforementioned base generator or the diamine represented by the formula (1) is dissolved in a solvent contained in the aforementioned composition at 23° C. so as to have a concentration of 0.55 mmol / 40 g of the solvent.

[0034] Effects of the Invention

[0035] According to the present invention, a method for producing a polyamide having excellent appearance after heating can be provided. DETAILED DESCRIPTION

[0036] Hereinafter, the content of the present invention will be described in detail. It should be noted that "to" in the present specification is used to mean that the numerical values ​​described before and after it are the lower limit and the upper limit.

[0037] In this specification, measured values, various physical property values, and characteristic values ​​are values ​​at 23° C. unless otherwise specified.

[0038] In addition, the "mass part" in this specification represents the relative amount of a component, and the "mass %" represents the absolute amount of a component.

[0039] In this specification, polyamide before solid phase polymerization is sometimes referred to as prepolymer to distinguish it from polyamide after solid phase polymerization. In addition, when simply referred to as polyamide, it means to include both prepolymer and polyamide after solid phase polymerization.

[0040] The method for producing a polyamide of the present invention (hereinafter sometimes referred to as the "production method of the present invention") is characterized in that it includes: a step of heating a composition comprising a diamine represented by formula (1), a dicarboxylic acid, and a solvent (hereinafter sometimes referred to as the "monomer composition"); and a step of removing the solvent during the heating step of the composition and after the heating step, or after the heating step, and an operation of adding a basic compound and / or a base generating agent to the monomer composition during the heating step of the monomer composition and / or before the heating step.

[0041] Formula (1)

[0042]

[0043] (In formula (1), X is a heteroatom, and n is an integer of 0 to 5. The portion of the ring containing X represents a cyclic structure containing X.)

[0044] By adopting such a configuration, a polyamide having excellent appearance after heating can be obtained. More specifically, the yellowing index (ΔYI) can be kept low.

[0045] The mechanism is not limited, but can be inferred as follows. That is, the diamine shown in formula (1) contains a cyclic structure containing heteroatoms represented by a tetrahydrofuran ring. It is believed that in the cyclic structure containing heteroatoms, protons are easily coordinated to heteroatoms. In the present invention, it is inferred that the basic compound is allowed to capture protons, which can inhibit the coordination of protons to the cyclic structure containing heteroatoms. At the same time, the protonation of the amino group possessed by the diamine shown in formula (1) is inhibited, thereby maintaining the nucleophilic ability of the amino group. As a result, it is inferred that amidation becomes easier to proceed.

[0046] Furthermore, in the production method of the present invention, by carefully selecting the type of the basic compound, a polyamide having a high 5% weight loss temperature can be obtained.

[0047] Hereinafter, the production method of the present invention will be described in detail.

[0048] The production method of the present invention includes: a step of heating a composition comprising a diamine represented by formula (1), a dicarboxylic acid, and a solvent (hereinafter sometimes referred to as a "monomer composition"); and a step of removing the solvent during the heating step of the composition and after the heating step, or after the heating step.

[0049] Formula (1)

[0050]

[0051] (In formula (1), X is a heteroatom, and n is an integer of 0 to 5. The portion of the ring containing X represents a cyclic structure containing X.)

[0052] First, the diamine represented by the formula (1) contained in the monomer composition will be described.

[0053] In the above formula (1), X is a nitrogen atom, an oxygen atom or a sulfur atom, preferably an oxygen atom or a sulfur atom, and more preferably an oxygen atom.

[0054] In the above formula (1), the ring portion including X is preferably a heterocyclic ring consisting of 1 heteroatom and 2 to 8 carbon atoms, more preferably a heterocyclic ring consisting of 1 heteroatom and 3 to 5 carbon atoms, and further preferably a heterocyclic ring consisting of 1 heteroatom and 4 carbon atoms. The heterocyclic ring may be an aromatic ring or a non-aromatic ring, and is preferably a non-aromatic ring.

[0055] Specific examples of the cyclic structure including X include a furan ring, a tetrahydrofuran ring, a thiophene ring, and a tetrahydrothiophene ring. A furan ring and a tetrahydrofuran ring are preferred, and a tetrahydrofuran ring is more preferred.

[0056] In the above formula (1), n ​​is preferably 1 or 2, and more preferably 1, respectively and independently.

[0057] The diamine represented by formula (1) is preferably a diamine represented by formula (2).

[0058] Formula (2)

[0059]

[0060] (In formula (2), n is an integer from 0 to 5.)

[0061] n in formula (2) has the same meaning as n in formula (1), and the preferred range is also the same.

[0062] Furthermore, the diamine represented by formula (1) is preferably 2,5-bis(aminomethyl)tetrahydrofuran.

[0063] The monomer composition may contain only one type of the diamine represented by formula (1), or may contain two or more types.

[0064] Furthermore, the monomer composition may contain diamines other than the diamine represented by formula (1) without departing from the gist of the present invention. Examples of diamines other than the diamine represented by formula (1) include aliphatic diamines (including alicyclic diamines) and aromatic diamines.

[0065] As specific examples of aliphatic diamines, reference may be made to paragraph 0016 of International Publication No. 2016 / 056340, the contents of which are incorporated herein. As aromatic diamines, reference may be made to paragraph 0052 of International Publication No. 2017 / 126409, the contents of which are incorporated herein.

[0066] Moreover, as another diamine, 2, 5- bis (aminomethyl) furan can also be illustrated.

[0067] In the present invention, the proportion of the diamine represented by formula (1) among the diamines contained in the monomer composition is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 99% by mass or more, and may be substantially 100% by mass. Substantially 100% by mass means that all diamines except diamines not intentionally contained such as impurities are diamines represented by formula (1).

[0068] Next, the dicarboxylic acid contained in the monomer composition will be described.

[0069] The type of dicarboxylic acid contained in the monomer composition is not particularly limited, and a wide range of known dicarboxylic acids can be used. An aromatic dicarboxylic acid and / or an aliphatic dicarboxylic acid is preferred, and an aromatic dicarboxylic acid is more preferred.

[0070] Examples of the aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 4,4′-methylenebis(2-methylcyclohexane-1-carboxylic acid), 4,4′-methylenebis(cyclohexane-1-carboxylic acid), decahydro-1,4-naphthalenedicarboxylic acid, 4,4′-oxybis(cyclohexane-1-carboxylic acid) and 4,4′-thiobis(cyclohexane-1-carboxylic acid). Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid are preferred, and glutaric acid, adipic acid and sebacic acid are more preferred.

[0071] Examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, phthalic acid, 1,2-naphthalene dicarboxylic acid, 1,3-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid. Isophthalic acid and terephthalic acid are more preferred, and terephthalic acid is further preferred.

[0072] In the present invention, it is particularly preferred that the dicarboxylic acid contained in the monomer composition contains at least one selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, glutaric acid, adipic acid, and sebacic acid, and terephthalic acid is more preferred.

[0073] The monomer composition may contain only one dicarboxylic acid or two or more dicarboxylic acids.

[0074] Here, the lower limit of the molar ratio (A / C ratio) of diamine to dicarboxylic acid in the monomer composition used in the present invention is preferably 0.8<A / C, more preferably 1.0≤A / C, and may be 1.0<A / C. In addition, the upper limit of the A / C ratio is preferably A / C<1.2. By setting the ratio to be less than the upper limit, the appearance of the polyamide after heating can be further improved, and the heat resistance (5% weight loss temperature) can be further improved.

[0075] The monomer composition used in the present invention may also include raw material monomers constituting polyamides other than the above-mentioned diamines and dicarboxylic acids. Specifically, examples include lactams such as ε-caprolactam, valerolactam, laurolactam, undecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like. In the monomer composition used in the present invention, among the raw material monomers (raw material monomers such as diamines, dicarboxylic acids, lactams, and aminocarboxylic acids) as the constituent units of polyamides, the total ratio of diamines and dicarboxylic acids is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably substantially 100% by mass. Substantially 100% by mass means that all of them are diamines or dicarboxylic acids, except for raw material monomers not intentionally included such as impurities.

[0076] Next, the solvent contained in the monomer composition will be described. As the solvent, any known solvent may be used without departing from the gist of the present invention, and examples thereof include water, methanol, and ethanol, and water is preferred.

[0077] The ratio of the solvent in the monomer composition used in the present invention is, for example, 20 to 80% by mass. In the monomer composition used in the present invention, preferably 90% by mass or more of the solvent is water, and may be 95% by mass or more, or 99% by mass or more.

[0078] The monomer composition used in the present invention may contain only one solvent or two or more solvents. When two or more solvents are contained, the total amount is preferably within the above range.

[0079] The monomer composition used in the present invention may contain other components such as additives commonly used in the synthesis of polyamides in addition to the above. Specifically, reaction accelerators, antioxidants, catalysts, dyes, pigments, chain inhibitors, lubricants, flame retardants, light stabilizers, plasticizers, nucleating agents, etc. other than the corresponding alkaline compounds and base generating agents may be exemplified. In addition, sodium acetate, calcium acetate, etc. for preventing gelation or fish eyes may also be exemplified as other components. The total amount of the above-mentioned other components in the monomer composition is preferably 3 parts by mass or less, and more preferably 1 part by mass or less, relative to 100 parts by mass of the raw monomers contained in the monomer composition.

[0080] Next, the step of heating the monomer composition and the step of removing the solvent during and after the heating step or after the heating step in the production method of the present invention are described.

[0081] In the present invention, by heating the monomer composition, diamine and dicarboxylic acid are usually polymerized in a molten state to form a low molecular weight polyamide (prepolymer). In addition, the process of removing the solvent is carried out during the heating process of the composition and after the heating process, or after the heating process, but is preferably carried out after the heating process. In addition, when removing the solvent, it is preferred to remove the condensed water together. The removal of the solvent is carried out by releasing the solvent from the reaction system (such as a reaction container) to the outside of the system. In the manufacturing method of the present invention, even when the solvent is removed after the heating process, the condensed water can be removed by the heating process.

[0082] Here, heating means applying heat. By applying heat, the temperature usually rises, but it also includes an operation of maintaining a high temperature state.

[0083] The maximum heating temperature of the prepolymer of the monomer composition is preferably 150°C or higher, more preferably 180°C or higher, and even more preferably 190°C or higher. By setting the temperature to be higher than the lower limit, discoloration of the prepolymer can be effectively suppressed and the degree of polymerization can be increased. In addition, the heating temperature of the monomer composition is preferably 260°C or lower, more preferably 250°C or lower, even more preferably 230°C or lower, and even more preferably 220°C or lower. By setting the temperature to be lower than the upper limit, discoloration of the prepolymer can be more effectively suppressed.

[0084] The heating time is preferably 0.5 hours or longer, more preferably 1 hour or longer, and the upper limit of the heating time is preferably 4 hours or shorter, more preferably 3 hours or shorter.

[0085] The monomer composition may also be pressurized during the heating in the stage of obtaining the prepolymer, and the pressure at this time is preferably 0.1 MPa or more. By setting it to above the lower limit, the formation of the prepolymer based on diamine and dicarboxylic acid can be carried out more effectively. In addition, the pressure is preferably 5 MPa or less.

[0086] Next, the operation of adding a basic compound and / or a base generator (preferably a basic compound) to the monomer composition during and / or before the heating step (preferably during the heating step) of the monomer composition in the production method of the present invention is described.

[0087] In the production method of the present invention, it is presumed that amidation is facilitated by adding a basic compound as described above.

[0088] On the other hand, in the production method of the present invention, the base generator is a compound that generates a basic compound when a stimulus such as heat is applied. Therefore, even when a base generator is added, a basic compound is generated when the monomer composition is heated, etc., and it is presumed that amidation is facilitated as described above.

[0089] The basic compound used in the present invention and the basic compound generated by the base generator (hereinafter sometimes referred to as "basic compound etc.") are not particularly limited, but are preferably weaker in basicity than the diamine represented by formula (1). Specifically, the value obtained by subtracting the pH of the basic compound etc. from the pH of the diamine represented by formula (1) is preferably 0.1 or more, and more preferably 0.2 or more. The upper limit of the value obtained by subtracting the pH of the basic compound etc. from the pH of the diamine represented by formula (1) is preferably 5 or less, more preferably 4 or less, further preferably 3 or less, further preferably 2 or less, and further preferably 1 or less. The pH here refers to the pH of a solution when the basic compound etc. or the diamine represented by formula (1) is dissolved in a solvent contained in the monomer composition so as to have a concentration of 0.55 mmol / 40 g of solvent at 23°C. In addition, when two or more diamines represented by formula (1) are used, the pH of the mixture thereof is the above pH. Furthermore, when two or more basic compounds and / or basic compounds generated by the base generator are used, the pH of the mixture of these basic compounds is the above pH. Compared with the diamine represented by formula (1), the basic compound or the like has weaker basicity, so the salt of the diamine represented by formula (1) and the dicarboxylic acid is preferentially formed, and it is presumed that the basic compound can effectively capture the remaining protons. In particular, by setting the upper limit of the difference between the pH of the diamine represented by formula (1) and the pH of the basic compound or the like to 2 or less, the ΔYI after heating is further reduced, and further, there is a tendency that the 5% weight loss temperature is further increased.

[0090] In addition, the pH of the basic compound used in the present invention is preferably 7 to 11. The pH here refers to the pH of a solution when the basic compound is dissolved in a solvent contained in the monomer composition in a concentration of 0.55 mmol / 40 g of solvent at 23° C. By setting such a structure, the nucleophilic ability of the amino group can be maintained, and the coordination of the proton to the furan ring can be more effectively suppressed.

[0091] The basic compound or the like is preferably selected from ammonia, organic amines, salts of ammonia and weak acids, and metal salts of weak acids, more preferably selected from ammonia and metal salts of weak acids, and further preferably ammonia.

[0092] In addition, by using ammonia, an organic amine or a salt of ammonia and a weak acid (further ammonia or a salt of ammonia and a weak acid, especially ammonia), a polyamide with better heat resistance can be obtained. Specifically, a polyamide with a higher 5% weight loss temperature can be obtained. In particular, a higher 5% weight loss temperature can be achieved at the prepolymer stage.

[0093] The organic amine is preferably selected from trialkylamine, dialkylamine, and monoalkylamine. The number of carbon atoms in the alkyl group constituting the alkylamine is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3.

[0094] Examples of the weak acid used in the salt of ammonia and a weak acid include carbonic acid and acetic acid, and acetic acid is preferred.

[0095] On the other hand, the weak acid used in the metal salt of a weak acid can be exemplified by carbonic acid and acetic acid, preferably acetic acid. In addition, the metal used in the metal salt of a weak acid is preferably an alkali metal or an alkaline earth metal, more preferably an alkali metal, further preferably lithium, sodium, potassium, and further preferably potassium.

[0096] The total amount of the alkaline compound and / or the base generating agent is preferably 0.1 mol or more, more preferably 0.3 mol or more, and may be 1 mol or more, and may be 5 mol or more, relative to 100 mol of the dicarboxylic acid contained in the monomer composition. By setting it to be above the aforementioned lower limit, the appearance of the obtained polyamide is better, and the degree of polymerization tends to be further improved. On the other hand, the upper limit of the total amount of the alkaline compound and / or the base generating agent is preferably 100 mol or less, more preferably 60 mol or less, and further preferably 15 mol or less, relative to 100 mol of the dicarboxylic acid contained in the monomer composition. By setting it to be below the aforementioned upper limit, there is a tendency to obtain a prepolymer with a higher 5% weight loss temperature.

[0097] The basic compound and the base generating agent may be used alone or in combination of two or more. When two or more are used, the total amount is preferably within the above range.

[0098] Here, preferred physical properties of the above-mentioned prepolymer are described.

[0099] The prepolymer is a polymer having two or more amide bonds, and has a weight average molecular weight of usually 3,000 or more, preferably 5,000 or more, and usually 20,000 or less, more preferably 15,000 or less.

[0100] The number average molecular weight of the prepolymer is usually 2,000 or more, preferably 3,000 or more, and is usually 10,000 or less, more preferably 8,000 or less.

[0101] The lower limit of the 5% weight loss temperature of the prepolymer is, for example, 260°C or higher, preferably 340°C or higher, more preferably 350°C or higher, further preferably 360°C or higher, and further preferably 380°C or higher. The upper limit of the 5% weight loss temperature of the prepolymer is, for example, 410°C or lower, and may be 400°C or lower. When ammonia, an organic amine, or a salt of ammonia and a weak acid is used as the basic compound, such a high weight loss temperature can be effectively obtained. In particular, it is effective when ammonia is used as the basic compound.

[0102] The 5% weight loss temperature of the prepolymer is measured by the method described in Examples below.

[0103] In the method for producing polyamide of the present invention, the prepolymer may be used as polyamide as it is, or may be further heated. When the prepolymer is used as polyamide as it is, the prepolymer may be purified and used.

[0104] In the method for producing polyamide of the present invention, after the step of heating the monomer composition to remove the solvent, it is preferably further heated under reduced pressure. In the present invention, by heating the prepolymer under reduced pressure (preferably under vacuum), additional polymerization proceeds, and a polyamide with a higher molecular weight (polyamide after solid phase polymerization) can be obtained.

[0105] The maximum heating temperature of the prepolymer heating temperature (heating temperature during solid phase polymerization) is preferably 220°C or more, more preferably 230°C or more, further preferably 240°C or more, and further preferably 245°C or more. By setting it to be above the aforementioned lower limit, the late polycondensation (solid phase polymerization) of the prepolymer tends to proceed more effectively. In addition, the heating temperature of the prepolymer is preferably 300°C or less, more preferably 280°C or less, further preferably 270°C or less, and further preferably 260°C or less. By setting it to be below the aforementioned upper limit, modification and discoloration can be more effectively suppressed.

[0106] The heating time of the prepolymer is preferably 0.25 hours or longer, more preferably 0.5 hours or longer. The upper limit of the heating time is preferably 5 hours or shorter, more preferably 3 hours or shorter.

[0107] Next, preferred physical properties of the polyamide obtained by the production method of the present invention after solid phase polymerization will be described.

[0108] The weight average molecular weight of the polyamide obtained by the solid phase polymerization in the production method of the present invention is preferably 30000 or more, more preferably 40000 or more, 50000 or more, or 60000 or more. In addition, the weight average molecular weight is, for example, 300000 or less, 200000 or less, or 150000 or less.

[0109] The number average molecular weight of the polyamide obtained by the production method of the present invention after solid phase polymerization is preferably 5000 or more, more preferably 8000 or more, further preferably 10000 or more, and may be 11000 or more, or 13000 or more. In addition, the number average molecular weight is, for example, 50000 or less, 30000 or less, or 20000 or less.

[0110] The dispersity (Mw / Mn) of the polyamide after solid phase polymerization obtained in the manufacturing method of the present invention can be 1.5 or more, or 2.0 or more. By setting it to above the aforementioned lower limit, the mechanical strength of the polyamide obtained tends to be higher. In addition, the dispersity (Mw / Mn) of the polyamide after solid phase polymerization is preferably 10.0 or less, more preferably 8.0 or less, and further preferably 6.0 or less. By setting it to below the aforementioned upper limit, there are few oligomers, so the heat resistance is high, and the moldability also tends to become good.

[0111] The weight average molecular weight and the number average molecular weight are measured by the method described in Examples below.

[0112] The 5% weight loss temperature of the polyamide obtained by the production method of the present invention after solid phase polymerization is preferably 371°C or higher, more preferably 380°C or higher, further preferably 385°C or higher, and further preferably 390°C or higher. By setting the temperature to be higher than the above lower limit (particularly 390°C or higher), it can be preferably used for applications requiring heat resistance. The upper limit of the 5% weight loss temperature of the polyamide after solid phase polymerization is not particularly limited, and is, for example, 410°C or lower, and may be 400°C or lower.

[0113] The 5% weight loss temperature is measured by the method described in Examples below.

[0114] The yellowing index (ΔYI) of the polyamide after solid phase polymerization obtained in the production method of the present invention is preferably 30 or less, more preferably 20 or less, further preferably 15 or less, further preferably 13 or less, further preferably 12 or less. By setting it below the above upper limit, a molded product with more suppressed coloring can be obtained. The lower limit of ΔYI of the polyamide after solid phase polymerization is not particularly limited, for example, 1 or more is practical, and 5 or more can also fully satisfy the required performance.

[0115] ΔYI is measured by the method described in Examples below.

[0116] The solid phase polymerized polyamide obtained by the production method of the present invention preferably satisfies at least one of the above-mentioned weight average molecular weight, number average molecular weight, degree of dispersion, 5% weight loss temperature and yellowing index (ΔYI), more preferably satisfies two or more of them, and even more preferably satisfies all of them.

[0117] Next, the uses of the polyamide obtained by the production method of the present invention will be described.

[0118] The polyamide obtained by the production method of the present invention can be used in the form of a resin composition containing the polyamide, and can also be used in the form of a molded article obtained by molding the resin composition.

[0119] For details of the resin composition, the molding method of the molded article, the use of the molded article, etc., reference may be made to paragraphs 0026 to 0040 of Japanese Patent Application Publication No. 2019-026686, paragraph 0039 of Japanese Patent Application Publication No. 2018-165298, and paragraphs 0045 to 0048 of Japanese Patent Application Publication No. 2018-087319, and these contents are incorporated into this specification.

[0120] Example

[0121] The present invention is further specifically described by enumerating examples below. As long as it does not depart from the gist of the present invention, the materials, dosage, ratio, processing content, processing steps etc. shown in the following examples can all be appropriately changed. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0122] <Synthesis Example of 2,5-bis(aminomethyl)tetrahydrofuran>

[0123] 20.70 g (0.1641 mol) of 2,5-bis(aminomethyl)furan (manufactured by Carbosynth, FB187031801), 120 mL of tetrahydrofuran, and 8.00 g of Rh catalyst-containing material (manufactured by NECHEMCAT CORPORATION, 317-160042) were weighed and placed in a 300 cc autoclave reaction container. After being fully substituted with nitrogen, hydrogen was filled to 6 MPaG. After reacting at 90°C for 1 hour, the reaction solution was taken out from the reaction container and filtered under pressure under an Ar atmosphere. The product was subjected to solvent distillation to obtain a crude product, which was then purified by distillation under reduced pressure at 1 hPa and 130°C to obtain 2,5-bis(aminomethyl)tetrahydrofuran.

[0124] The Rh catalyst-containing material is obtained by supporting Rh catalyst powder on carbon, and contains 55 mass % of water and 45 mass % of Rh catalyst, wherein 5 mass % of the Rh catalyst is Rh and 40 mass % is carbon.

[0125] The pH of the solution obtained by dissolving 2,5-bis(aminomethyl)tetrahydrofuran in pure water at 23° C. so as to have a concentration of 0.55 mmol / 40 g of pure water was 11.01.

[0126] Example 1

[0127] <Synthesis of Polyamide>

[0128] In a 30cc autoclave reaction vessel, weighed terephthalic acid (PTM6633 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 0.712g (3.08mmol), pure water 0.60g, 2,5-bis(aminomethyl)tetrahydrofuran synthesized above 0.472g (3.08mmol), 7% by mass ammonia water (prepared with special grade ammonia water (ammonia 28% by mass) manufactured by Kishida Chemical Co., Ltd.) 15μL were added, and after sufficient replacement with nitrogen, the system was heated to 200°C while stirring. After 1.5 hours, the generated water and the water added were removed to the outside of the system, and heating was continued for further 30 minutes. After the reaction, the prepolymer was taken out of the reaction vessel and subjected to post-condensation (solid phase polymerization) in a vacuum dryer at 250°C for 1 hour to obtain a polyamide.

[0129] <5% weight loss temperature>

[0130] The 5% weight loss temperature is measured for the prepolymer obtained in the above synthesis example and the polyamide after solid phase polymerization. Specifically, the prepolymer or the polyamide after solid phase polymerization as the measurement object is heated from 30°C to 400°C at a heating rate of 10.5°C / min. An aluminum pan is used for reference. The temperature at which the initial sample mass reaches 95% is defined as the 5% weight loss temperature, with the initial sample mass being 100%. The unit is expressed in °C.

[0131] For the measurement, TGDTA7220 manufactured by Hitachi High-Tech Science Corporation was used.

[0132] <Yellowing Intensity (ΔYI)>

[0133] Using hexafluoroisopropanol as a solvent, 42.5 mg of the above-mentioned solid phase polymerized polyamide was dissolved in 60 mL of the solvent, and the concentration was adjusted to be the same for all to obtain a sample solution. The yellowness (YI) of the solvent and the sample solution was calculated, and the difference in yellowness between the sample solution and the solvent was defined as the yellowing degree (ΔYI).

[0134] For the measurement, Spectro Color Meter SE2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used.

[0135] <Measurement of Weight Average Molecular Weight (Mw) and Number Average Molecular Weight (Mn)>

[0136] The Mw and Mn of the solid phase polymerized polyamide were measured by gel permeation chromatography. Specifically, 5 mL of 1,1,1,3,3,3-hexafluoroisopropanol was added to 10 mg of the solid phase polymerized polyamide to be measured, and the mixture was filtered with a membrane filter (pore size 0.2 μm) to prepare a sample solution.

[0137] The measurement was performed using GPC-104 (RI detector) manufactured by SHOKO SCIENTIFIC CO., LTD. The column used was Shodex GPC LF-404 manufactured by Showa Denko K.K. If the gel permeation chromatography apparatus and column are difficult to obtain due to discontinuation of production, other equipment with equivalent performance may be used.

[0138] Eluent: 1,1,1,3,3,3-hexafluoroisopropanol (+10mmol sodium trifluoroacetate)

[0139] The measurement conditions are shown below.

[0140] Flow rate: 0.3mL / min

[0141] Column temperature: 40°C

[0142] Standard material: polymethyl methacrylate

[0143] Sample concentration: 0.2 mass / volume %

[0144] Injection volume: 10 μL

[0145] The degree of dispersion (Mw / Mn) was calculated from the values ​​of Mw and Mn measured above.

[0146] Example 2, Example 3, Example 4, Example 5, Comparative Example 1

[0147] In Example 1, the type and addition amount of the basic compound were changed as shown in Table 1, and the other operations were carried out in the same manner. Potassium acetate was 166-03172 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., and the powder was directly charged into an autoclave reaction vessel together with terephthalic acid, 2,5-bis(aminomethyl)tetrahydrofuran and pure water.

[0148] The results are shown in Table 1 below.

[0149] [Table 1]

[0150]

Claims

1. A method for producing a polyamide, comprising: A step of heating a composition comprising a diamine represented by formula (2), a dicarboxylic acid, and a solvent; and a step of removing the solvent during or after the heating step of the composition, The step of heating the composition and / or before the heating step includes adding a basic compound and / or a base generating agent to the composition. Formula (2) In formula (2), n is an integer from 0 to 5, The total amount of the basic compound and / or the base generator is 0.1 to 100 mol relative to 100 mol of the dicarboxylic acid contained in the composition.

2. The method for producing polyamide according to claim 1, wherein: In the step of heating the composition, the basic compound and / or the base generating agent is added to the composition.

3. The method for producing a polyamide according to claim 1 or 2, wherein: The diamine represented by the formula (2) includes 2,5-bis(aminomethyl)tetrahydrofuran.

4. The method for producing a polyamide according to claim 1 or 2, wherein: The composition comprises a diamine and a dicarboxylic acid in a molar ratio of 0.8<diamine / dicarboxylic acid<1.

2. 5 . The method for producing polyamide according to claim 1 , comprising the step of adding the basic compound to the composition.

6. The method for producing a polyamide according to claim 1 or 2, wherein: The basic compound and the basic compound generated by the base generator each include at least one selected from ammonia, an organic amine, a salt of ammonia and a weak acid, and a metal salt of a weak acid.

7. The method for producing polyamide according to claim 6, wherein: The basic compound and the basic compound generated by the base generator each include at least one selected from ammonia and a metal salt of a weak acid.

8. The method for producing a polyamide according to claim 1 or 2, wherein: The pH of the solution when the basic compound and the basic compound generated by the base generator are dissolved in the solvent contained in the composition at 23° C. so as to have a concentration of 0.55 mmol / 40 g of the solvent is 7 to 11.

9. The method for producing a polyamide according to claim 1 or 2, wherein: The dicarboxylic acid includes at least one selected from phthalic acid, isophthalic acid, terephthalic acid, glutaric acid, adipic acid and sebacic acid.

10. The method for producing a polyamide according to claim 1 or 2, wherein: After the step of removing the solvent, the method further includes heating under reduced pressure.

11. The method for producing a polyamide according to claim 1 or 2, wherein: In the composition, a value obtained by subtracting the pH of the basic compound and the basic compound generated by the base generator from the pH of the diamine represented by formula (2) is 0.1 or more and 5 or less, and the pH is the pH of a solution when the basic compound, the basic compound generated by the base generator or the diamine represented by formula (2) is dissolved in a solvent contained in the composition at 23° C. in a concentration of 0.55 mmol / 40 g of solvent.

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