Adipic acid crystal

Abstract

With respect to polymerization using adipic acid as a starting material, the present invention is capable of increasing the productivity of a polymer by using, as a starting material, adipic acid crystals that contain a boron compound and have an elemental boron content of 1 ppm to 1,000 ppm inclusive, or adipic acid crystals that contain fluorescent impurities and have a fluorescence intensity of 0.55 or more as calculated by the following formulae 1 to 3 when fluorescence measurement is performed with slit widths on both the excitation side and the observation side set to 3 nm. (Formula 1) Fluorescence intensity A = (Sum of fluorescence intensities at 400-436 nm (every 2 nm) at excitation wavelengths of 300-340 nm (every 5 nm)) / 171 (Formula 2) Scattering intensity B (Raman scattering intensity) = (Sum of scattering intensities at 378-382 nm (every 2 nm) at an excitation wavelength of 340 nm) / 3 (Formula 3) Fluorescence intensity of adipic acid crystals = (Fluorescence intensity A) / (scattering intensity B)

Description

Adipic acid crystals

[0001] This invention relates to adipic acid crystals, which have adipic acid as their main component, and to polyamides and polyesters made from these adipic acid crystals.

[0002] Adipic acid is used as a monomer for polyamides, and polyamide 6,6, obtained by polycondensation of hexamethylenediamine and adipic acid, is widely used in various applications, including fibers and resins, due to its excellent properties. Specifically, polyamide 6,6 fibers are used in clothing applications, taking advantage of their high strength, abrasion resistance, and elasticity, and in industrial applications such as airbags and tire cords, taking advantage of their high strength, high heat resistance, and lightweight properties. Polyamide 6,6 resin is used as an injection molding material in a wide range of applications, including automobiles, industrial parts, and home appliances, due to its excellent mechanical strength, heat resistance, abrasion resistance, and chemical resistance.

[0003] Furthermore, adipic acid is also used as a monomer for polyesters. For example, copolymerizing adipic acid with 1,4-butanediol, terephthalic acid, or succinic acid yields polybutylene adipate terephthalate (PBAT) and polybutylene succinate adipate (PBSA), respectively. Because these polyesters are biodegradable, they are increasingly being used in environmentally conscious applications such as compost bags, packaging and agricultural films, agricultural and forestry materials, and construction materials.

[0004] Adipic acid is industrially produced by nitrate oxidation of a mixture of cyclohexanone and cyclohexanol (KA oil) derived from petroleum, but nitrous oxide (N) has a high greenhouse effect. ２ O) Because a large amount of gas is produced as a by-product, there is a need for a method of producing adipic acid that does not produce nitrous oxide as a by-product during the manufacturing process. One method of producing adipic acid that does not produce nitrous oxide as a by-product and is attracting attention is a method of producing adipic acid using biomass, which is a renewable resource, or substances that can be derived from biomass resources, as raw materials.

[0005] Known methods for producing adipic acid from biomass resources include a fermentation method using sugars and fatty acids as raw materials (Non-Patent Document 1), and a method in which an acid is added to 3-hydroxyadipic acid produced by fermentation using sugars as raw materials to form 3-hydroxyadipic acid-3,6-lactone, and then the mixture is reacted with hydrogen in an aqueous solvent in the presence of a hydrogenation catalyst to produce adipic acid (Patent Document 1). However, adipic acid derived from biomass resources contains a wide variety of impurities derived from the biomass resources, and these impurities are known to inhibit polymer polymerization or degrade the quality of the polymer. However, because the impurities are so diverse, purification is difficult, and practical application has not yet been achieved.

[0006] Furthermore, a method for producing polyamide 6,6 is known in which boric acid is added during the polycondensation of adipic acid and hexamethylenediamine to suppress the volatilization of hexamethylenediamine and improve the production efficiency of polyamide 6,6 (Patent Document 2).

[0007] International Publication No. 2021 / 060335, Chinese Patent Application Publication No. 115612094

[0008] Biochemical Engineering Journal, vol. 105, p. 16-26 (2016).

[0009] Polyamides and polyesters are manufactured by polycondensation, but this reaction requires heating above the melting point of the polymer, necessitating enormous amounts of energy for production. Furthermore, prolonged heating can lead to side reactions during polymerization and a decrease in the polymer's properties.

[0010] Therefore, the objective of this invention is to find a method for producing energy-saving and economically efficient polyamides and polyesters by improving the polymerization rate and shortening the polymerization time.

[0011] As a result of diligent research to solve the above problems, the inventors of the present invention have found that by including a specific amount of a boron compound in adipic acid crystals, which are raw materials for polyamides and polyesters, the polymerization rate of the polymer, as evaluated by the number-average molecular weight of the polymer, increases when reaction conditions such as temperature, pressure, and time in polymer polymerization are kept the same.

[0012] Furthermore, we discovered that certain fluorescent impurities, which can be detected in relatively large quantities in adipic acid crystals derived from biomass resources, do not inhibit polymer polymerization. Rather, in polymer polymerization using adipic acid as a raw material, they contribute to improving the polymerization rate of the polymer, as evaluated by the weight-average molecular weight of the polymer when the reaction conditions such as temperature, pressure, and time are kept the same. This discovery led to the completion of the present invention.

[0013] In other words, the present invention consists of the following (1) to (38): (1) an adipic acid crystal containing adipic acid derived from biomass resources. (2) the adipic acid crystal according to (1), wherein the biomass is cellulose-containing biomass. (3) an adipic acid crystal containing a boron compound, wherein the content of boron element is 1 ppm or more and 1000 ppm or less. (4) an adipic acid crystal containing a fluorescent impurity, wherein when fluorescence measurement is performed with both the excitation and observation slit widths set to 3 nm, the fluorescence intensity of the adipic acid crystal calculated by the following formulas 1 to 3 is 0.55 or more. (Equation 1) Fluorescence intensity A = {Sum of fluorescence intensities from 400 to 436 nm (at 2 nm intervals) at excitation wavelengths of 300 to 340 nm (at 5 nm intervals)} / 171 (Equation 2) Scattering intensity B (Raman scattering intensity) = {Sum of scattering intensities from 378 to 382 nm (at 2 nm intervals) at excitation wavelength of 340 nm} / 3 (Equation 3) Fluorescence intensity of adipic acid crystal = Fluorescence intensity A / Scattering intensity B (5) The adipic acid crystal according to (3) or (4), wherein the boron compound or the fluorescent impurity is an impurity derived from biomass resources. (6) The adipic acid crystal according to (3) or (4), wherein the boron compound or the fluorescent impurity is an impurity contained in adipic acid obtained by chemical synthesis from a C6 hydroxycarboxylic acid or unsaturated dicarboxylic acid or its derivative derived from biomass resources. (7) The adipic acid crystal according to (6), wherein the impurity is an impurity contained in adipic acid obtained by chemical synthesis from 3-hydroxyadipic acid or its derivatives derived from biomass resources. (8) The adipic acid crystal according to (6), wherein the impurity is an impurity contained in adipic acid obtained by microbial fermentation using carbohydrates derived from biomass resources as raw materials. (9) The adipic acid crystal according to (3) or (4), wherein the adipic acid crystal is obtained by crystallizing an adipic acid-containing solution. (10) The adipic acid crystal according to (9), wherein the crystallization step includes a step of crystallizing an adipic acid-containing solution, a step of solid-liquid separation of the adipic acid crystal and the crystallization mother liquor, and a step of circulating the crystallization mother liquor to the crystallization step. (11) The adipic acid crystal according to (3) or (4), wherein the adipic acid is a free form of adipic acid. (12) The adipic acid crystal according to (3) or (4), wherein the adipic acid content in the crystal is 99% by weight or more.(13) A method for producing adiponitrile, comprising the step of dehydrating adiponitrile crystals described in (3) or (4) in the presence of ammonia. (14) A method for producing hexamethylenediamine, comprising the step of hydrogenating adiponitrile obtained by the method described in (13). (15) A method for producing ε-caprolactam, comprising the step of reacting adiponitrile crystals described in (3) or (4) with hydrogen and ammonia in the presence of a catalyst. (16) A polyamide made from adiponitrile crystals described in (3) or (4) and a diamine as raw materials. (17) The polyamide according to (16), wherein the diamine is 1,4-butanediamine, 1,5-pentanediamine, or hexamethylenediamine. (18) The polyamide according to (17), wherein the polyamide is polyamide 4,6, polyamide 5,6, or polyamide 6,6. (19) A polyamide made from hexamethylenediamine and a dicarboxylic acid obtained by the method described in (14). (20) The polyamide according to (19), wherein the dicarboxylic acid is adipic acid or sebacic acid. (21) The polyamide according to (19), wherein the dicarboxylic acid raw material is adipic acid crystals described in (3) or (4). (22) The polyamide according to (20), wherein the polyamide is polyamide 6,6 or polyamide 6,10. (23) Polyamide 6 made from ε-caprolactam obtained by the method described in (15). (24) A polyester made from adipic acid crystals and glycols described in (3) or (4). (25) The polyester according to (24), wherein the glycols are 1,4-butanediol. (26) The polyester according to (25), wherein the polyester is polybutylene adipate terephthalate or polybutylene succinate adipate. (27) Resin pellets made from the polyamide according to (16). (28) Resin pellets made from the polyamide according to (19). (29) Resin pellets made from the polyamide 6 according to (23). (30) Resin pellets made from the polyester according to (24). (31) Fibers obtained by processing the resin pellets according to any one of (27) to (30). (32) Textile products made using the fibers according to (31).(33) The textile product according to (32), wherein the textile product is clothing, industrial material, building / housing material or living material. (34) A molded article made by processing resin pellets according to any of (27) to (30). (35) The molded article according to (34), wherein the molded article is an electrical / electronic equipment component, automobile part, machine part or building / housing material. (36) A polyester film made by processing the resin pellets of (30). (37) A film product made using the polyester film according to (36). (38) The film product according to (37), wherein the film product is a film for packaging materials or an agricultural film.

[0014] By using the adipic acid crystals of the present invention as a raw material, the polymerization time of the polymer can be shortened, and the productivity of the polymer can be improved.

[0015] The present invention will be described in detail below.

[0016] [Adipic Acid] Adipic acid is a six-carbon dicarboxylic acid. In the present invention, there are no particular restrictions on its origin as long as it contains boron compounds or fluorescent impurities as described later when crystallized. It may be petroleum-derived adipic acid or biomass-derived adipic acid, but biomass-derived adipic acid is preferred. Regarding adipic acid containing fluorescent impurities, there are no particular restrictions as long as it contains fluorescent impurities that emit fluorescence at specific wavelengths as described later when crystallized. However, since such fluorescent impurities are easily present when biomass-derived adipic acid is crystallized, biomass-derived adipic acid is more preferred.

[0017] Biomass resources are defined as renewable, biologically derived organic resources, excluding fossil resources. As described below, biomass resources are preferably plant biomass, and more preferably cellulose-containing biomass.

[0018] In this invention, adipic acid may be adipic acid free form (free adipic acid), an adipic acid salt, an adipic acid ester, or a mixture thereof, and in this specification, these are collectively referred to as "adipic acid."

[0019] Examples of adipine salts include alkali metal salts, alkaline earth metal salts, or ammonium salts, specifically lithium salts, sodium salts, potassium salts, and ammonium salts.

[0020] Examples of adipic acid esters include alkyl esters, and specific alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. Carboxylic acid esters may be monoesters or diesters.

[0021] As adipic acid derived from biomass resources, adipic acid obtained by chemically synthesizing adipic acid from an intermediate using a 6-C6 hydroxydicarboxylic acid derived from biomass resources (preferably 3-hydroxyadipic acid, its salts or esters), a 6-C6 unsaturated dicarboxylic acid (preferably α-hydromuconic acid, its salts or esters), or a derivative thereof (preferably monolactone, more preferably 3-hydroxyadipic acid-3,6-lactone, its salts or esters) as an intermediate is a preferred specific example.

[0022] Specific examples of biomass resource-derived raw materials that serve as raw materials for adipic acid include monosaccharides such as glucose, mannose, galactose, fructose, sorbose, and tagatose, as well as pentoses such as arabinose, xylose, ribose, xylulose, and ribulose, disaccharides and polysaccharides such as pentosan, saccharose, starch, and cellulose, and starch saccharification liquids, molasses, cellulose-containing biomass saccharification liquids containing these, fatty acids such as butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, monotic acid, arachidic acid, eicosenoic acid, arachidonic acid, behenic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, lignoceric acid, and seracolenic acid, and polyalcohols such as glycerin, mannitol, xylitol, and ribitol.

[0023] [Adipic Acid Crystals] The adipic acid crystals of the present invention are characterized in that they mainly consist of adipic acid and contain boron compounds as minor components, which are composed of boron in a specific concentration range, or contain fluorescent impurities that emit fluorescence when irradiated with specific excitation light (hereinafter simply referred to as "fluorescent impurities"). Here, "main component" means that the adipic acid content in the adipic acid crystals is preferably 99% by weight or more, more preferably 99.5% by weight or more, even more preferably 99.9% by weight or more, and particularly preferably 99.99% by weight or more.

[0024] The adipic acid crystals of the present invention may be crystals of adipic acid-free form (free adipic acid), an adipic acid salt, or an adipic acid ester, but crystals of adipic acid-free form are preferred.

[0025] The boron compound used in this invention is not particularly limited and may be boron, an organoboron compound, or an inorganic boron compound. Examples of organoboron compounds include boric acid esters such as alkyl borate and aryl borate, boronic acid and its esters or salts, and boric acid and its esters or salts. Examples of inorganic boron compounds include boric acid and its salts, and borate minerals such as borax. Since these boron compounds exist in nature, they may also be contained in biomass resources. In particular, boric acid is known as an essential inorganic nutrient important for the structure and function of plant cell walls. Therefore, when producing adipic acid crystals using biomass resources, especially plant biomass resources, as raw materials, boric acid derived from the biomass resources may be included as an impurity in the adipic acid crystal production process. Thus, the amount of boric acid (boron) contained in the adipic acid crystals can be adjusted by controlling the production process of adipic acid crystals derived from biomass resources, preferably plant biomass.

[0026] The boron compound content in the adipic acid crystals of the present invention is characterized in that the lower limit of boron element is 1 ppm or more, preferably 1.2 ppm or more, more preferably 1.5 ppm or more, even more preferably 2 ppm or more, and the upper limit is 1000 ppm or less, preferably 500 ppm or less, more preferably 100 ppm or less, even more preferably 50 ppm or less, even more preferably 30 ppm or less, particularly preferably 10 ppm or less, and even more particularly preferably 5 ppm or less. By having the boron element content in the adipic acid crystals within this range, an effect is obtained in which the polymerization rate of the polymer, evaluated by the number-average molecular weight of the polymer when reaction conditions such as temperature, pressure, and time are kept the same in polymer polymerization using adipic acid crystals as a raw material, is improved. If the boron compound content in the adipic acid crystals is less than 1 ppm as boron element, the polymerization rate improvement effect will be small, and if it exceeds 1000 ppm, it is thought to lead to a decrease in physical properties such as a decrease in the crystallinity and melting point of the polymer. The boron compound content in the adipic acid crystals of the present invention is a value detected as the boron element content by an ICP (Inductively Coupled Plasma) mass spectrometer.

[0027] There are no particular restrictions on the method for incorporating a boron compound into adipic acid crystals; it may be prepared by mixing pure adipic acid and a boron compound prepared separately. For example, in the case of adipic acid produced from petroleum, the boron compound is not present as an impurity, or if present, it is only in trace amounts. Therefore, the content of the boron compound can be adjusted to a desired range by appropriately adding the boron compound to petroleum-derived adipic acid crystals.

[0028] Furthermore, as mentioned above, if boron compounds are present as impurities when biomass-derived adipic acid crystals are produced, they may be used as is if the boron compound content is within the range of the present invention, or if the boron compound content is low, the boron content may be adjusted appropriately by adding boron compounds, or conversely, if the boron compound content is too high, the adipic acid crystals of the present invention can be prepared by appropriately adjusting the purification process in adipic acid production.

[0029] As mentioned above, plant biomass is a preferred example of a biomass resource that serves as a raw material for the adipic acid crystals of the present invention. However, since boric acid is an essential inorganic nutrient important for the structure and function of plant cell walls, and cellulose is a major component of plant cell walls, cellulose-containing biomass is more preferred among plant biomass resources.

[0030] Although the details of the fluorescent impurities contained in the adipic acid crystals of the present invention are not yet clear, as shown in the examples, they are suitably contained in adipic acid obtained by chemical synthesis from biomass resources, particularly from C6 hydroxycarboxylic acids (preferably 3-hydroxycarboxylic acid, its salts or esters), C6 unsaturated dicarboxylic acids (preferably 3-hydroxyadipic acid, α-hydromuconic acid, their salts or esters), or their derivatives (preferably monolactone, more preferably 3-hydroxyadipic acid-3,6-lactone, their salts or esters), derived from biomass resources. Furthermore, the chemical structure of the fluorescent impurities is thought to have aromatic rings or conjugated electrons, and examples include aromatic amino acids such as tryptophan, phenylalanine, and tyrosine, pigment compounds such as chlorophyll, and microbial metabolites having multiple conjugated double bonds. These can be prominently contained in biomass resources, particularly in culture medium components for microbial culture, and in microorganisms and their metabolites. These fluorescent impurities, along with other biomass resource-derived impurities, are generally undesirable because they inhibit polymer polymerization or degrade polymer quality. However, the present invention, by using adipic acid crystals containing fluorescent impurities as a raw material, unexpectedly yields a technical effect: an improvement in the polymer polymerization rate, which is evaluated by the weight-average molecular weight of the polymer when reaction conditions such as temperature, pressure, and time are kept the same during polymer polymerization.

[0031] Fluorescent impurities are characterized by emitting fluorescence at 400–436 nm when a solid adipic acid crystal is irradiated with excitation light at 300–340 nm. The fluorescence intensity of the fluorescent impurities, a parameter correlated with the amount of fluorescent impurities contained in the adipic acid crystal, is measured using a fluorescence spectrophotometer. With both the excitation and observation slit widths set to 3 nm, the solid adipic acid crystal is first irradiated with excitation light at 300–340 nm at 5 nm intervals (9 excitation wavelengths), and the fluorescence intensity at 400–436 nm is measured at 2 nm intervals (19 fluorescence wavelengths). The average of the fluorescence intensities at a total of 171 points is defined as fluorescence intensity A (Equation 1 below). Next, in the fluorescence analysis described above, when a solid adipic acid crystal is irradiated with excitation light at an excitation wavelength of 340 nm, the scattering intensity of Raman scattered light at wavelengths of 378 to 382 nm is measured at 2 nm intervals, and the average value of the scattering intensities at these three points is defined as the scattering intensity B (Equation 2 below). The ratio of fluorescence intensity A to scattering intensity B (Equation 3 below) is defined as the fluorescence intensity of the adipic acid crystal containing fluorescent impurities.

[0032] Fluorescence intensity A = {Sum of fluorescence intensities at excitation wavelengths of 300-340 nm (at 5 nm intervals) and 400-436 nm (at 2 nm intervals)} / 171 ... (Equation 1).

[0033] Scattering intensity B (Raman scattering light intensity) = {sum of scattering intensities at excitation wavelength 340 nm from 378 to 382 nm (at 2 nm intervals)} / 3 ... (Equation 2).

[0034] The fluorescence intensity of adipic acid crystals = fluorescence intensity A / scattering intensity B ... (Equation 3).

[0035] Here, fluorescence and scattering intensity are normalized by the light intensity of each excitation wavelength, using light from a xenon lamp passed through a spectrometer as the excitation light source, and detecting fluorescence and scattering intensity by a photomultiplier tube (PMT).

[0036] The present invention is characterized in that the fluorescence intensity of the adipic acid crystal calculated from the above formulas 1 to 3 is 0.55 or higher. When the fluorescence intensity of the adipic acid crystal is within this range, the polymerization rate is improved when polyamide is polymerized using the adipic acid crystal as a raw material, resulting in an effect of increasing the molecular weight of the resulting polyamide. If the fluorescence intensity is less than 0.55, the effect of improving the polymerization rate is small, so the fluorescence intensity is 0.55 or higher, preferably 0.60 or higher. On the other hand, there is no particular upper limit to the fluorescence intensity of the adipic acid crystal, but it is estimated to be approximately 40.0 based on the estimated upper limit of the amount of such impurities that may be contained in the adipic acid crystal. However, if the content of fluorescent impurities is high, the substances estimated to be fluorescent impurities will inhibit polymer polymerization, which is thought to lead to a decrease in the polymerization rate and a decrease in polymer properties such as the melting point, so it is preferably 20.0 or less, more preferably 10.0 or less, even more preferably 5.0 or less, and particularly preferably 2.0 or less.

[0037] There are no particular restrictions on the method for incorporating fluorescent impurities into adipic acid crystals. They may be prepared by mixing separately prepared pure adipic acid with the aforementioned biomass resources, particularly components of culture media for microbial cultivation, or fluorescent impurities significantly present in microorganisms and their metabolites. For example, in the case of adipic acid produced from petroleum, the aforementioned fluorescent impurities are either not present or present in only trace amounts. Therefore, the content of boron compounds can be adjusted to a desired range by appropriately adding fluorescent impurities to petroleum-derived adipic acid crystals.

[0038] Furthermore, as mentioned above, if fluorescent impurities are present as impurities when biomass-derived adipic acid crystals are produced, they may be used as is if the fluorescent impurity content is within the range of the present invention. If the fluorescent impurity content is low, it may be adjusted by appropriately adding biomass resources, particularly components of culture media for microbial cultivation, or fluorescent impurities significantly present in microorganisms and their metabolites. Conversely, if the fluorescent impurity content is too high, the adipic acid crystals of the present invention can be prepared by appropriately adjusting the purification process in adipic acid production.

[0039] The adipic acid crystals of the present invention may have any characteristics of the adipic acid crystals containing the above boron compound and the adipic acid crystals containing the above fluorescent impurities, and may also have the characteristics of both the adipic acid crystals containing the above boron compound and the adipic acid crystals containing the above fluorescent impurities. However, it is preferable to have the characteristics of both the adipic acid crystals containing the above boron compound and the adipic acid crystals containing the above fluorescent impurities.

[0040] As a method for synthesizing or deriving adipic acid from biomass resources, a method of using a dicarboxylic acid having 6 carbon atoms derived from biomass resources as an intermediate for adipic acid synthesis is preferable as described above. As a method for producing the intermediate dicarboxylic acid having 6 carbon atoms, for example, a method for producing 3-hydroxyadipic acid and / or α-hydroxymuconic acid by microbial fermentation described in International Publication No. 2022 / 102635 can be mentioned. Further, it is preferable to purify the intermediate before synthesizing adipic acid. As a method for purifying the intermediate, for example, a method for purifying and recovering 3-hydroxyadipic acid-3,6-lactone by the method described in International Publication No. 2020 / 196459 can be mentioned. Further, when synthesizing adipic acid using a dicarboxylic acid having 6 carbon atoms as an intermediate, for example, an aqueous adipic acid solution can be obtained by a hydrogenation reaction using a hydrogenation catalyst in an aqueous solvent in the presence of hydrogen as described in International Publication No. 2021 / 060335. After crystallization of the obtained aqueous adipic acid solution, crystals of adipic acid can be obtained by solid-liquid separation, and the crystals can be suitably used as the adipic acid crystals in the present invention.

[0041] There are no particular restrictions on the crystallization method of adipic acid, and it can be carried out by commonly used methods. For example, a method of making adipic acid supersaturated by cooling an adipic acid-containing solution (cooling crystallization), a method of making adipic acid supersaturated by evaporating a solvent (water) (evaporation crystallization), a method of making it supersaturated by evaporating a solvent (water) and concentrating while cooling an adipic acid-containing solution (adiabatic crystallization), etc. Among the above crystallization methods, adiabatic crystallization can be preferably applied because the energy input for cooling can be reduced. The number of times of the above crystallization may be once, or may be carried out multiple times to further increase the purity, and it can be appropriately selected according to the purity of the obtained adipic acid crystals. Also, in the above crystallization, continuous crystallization, that is, continuous supply of an adipic acid-containing solution and continuous extraction of an adipic acid slurry may be carried out. In addition, seed crystals may be added during the above crystallization.

[0042] For the separation of the adipic acid crystals and the residual liquid (mother liquor) generated in the crystallization step, known solid-liquid separation methods can be applied. Specifically, the adipic acid crystals can be recovered by the decantation method, centrifugation, vacuum / pressure filtration, etc. The mother liquor after recovering the crystals is preferably recycled to the previous crystallization step, thereby increasing the overall adipic acid recovery rate.

[0043] Also, in order to increase the purity of the adipic acid crystals obtained in the crystallization step, the mother liquor adhering to the crystals may be washed with a washing liquid. As the washing liquid, in order to prevent the generated adipic acid crystals from dissolving and the crystal recovery rate from decreasing, it is preferable to use a poor solvent that does not dissolve adipic acid. As such a poor solvent, it is preferable to use a saturated aqueous solution of adipic acid. It is more preferable to dissolve a part of the adipic acid crystals obtained in the present invention in water to prepare a saturated aqueous solution and use it as the washing liquid. After the washing liquid is separated from the washed crystals by the above-mentioned solid-liquid separation method, it is preferably recycled to any step.

[0044] The following describes a detailed and preferred example of the method for producing adipic acid crystals according to the present invention, consisting of steps A to H based on the methods described in International Publication No. 2022 / 102635, International Publication No. 2020 / 196459, and International Publication No. 2021 / 060335.

[0045] (Step A) Prepare a 3-hydroxyadipic acid fermentation solution based on the method described in International Publication No. 2022 / 102635 (e.g., Example 10). Any raw materials can be used as fermentation raw materials, such as monosaccharides like glucose or sugar solutions derived from cellulose-containing biomass as described in International Publication No. 2024 / 009922.

[0046] (Steps B to E) From the 3-hydroxyadipic acid fermentation liquid obtained in Step A, 3-hydroxyadipic acid-3,6-lactone is obtained according to the method described in International Publication No. 2020 / 196459 (e.g., Example 3).

[0047] (Step B) The 3-hydroxyadipic acid fermentation liquid obtained in Step A is filtered through a microfiltration membrane to remove solid components such as microbial cells, and then treated with an ultrafiltration membrane (UF membrane) to remove proteins from the 3-hydroxyadipic acid aqueous solution.

[0048] (Step C) By adding an acid such as concentrated sulfuric acid to the UF membrane permeate containing 3-hydroxyadipic acid obtained in Step B, the pH is adjusted to less than 7, which is an acidic condition, and 3-hydroxyadipic acid-3,6-lactone is generated from 3-hydroxyadipic acid, thereby improving the recovery rate by the subsequent nanofiltration membrane (Step D).

[0049] (Step D) The aqueous solution containing 3-hydroxyadipic acid-3,6-lactone obtained in Step C is filtered through a nanofiltration membrane to obtain an aqueous solution containing 3-hydroxyadipic acid-3,6-lactone with impurities reduced from the permeate side of the membrane. When the concentration of 3-hydroxyadipic acid-3,6-lactone is low, the aqueous solution containing 3-hydroxyadipic acid-3,6-lactone obtained by nanofiltration membrane treatment requires a great deal of energy to remove water, which has a lower boiling point than 3-hydroxyadipic acid-3,6-lactone, so it is preferable to concentrate it. As a method of concentrating the permeate of the nanofiltration membrane, a method using a concentration device such as an evaporator is common and can be applied in the present invention as well, but since the heat capacity of water is much larger than that of an organic solvent, the energy and time required for concentration are enormous. On the other hand, concentration by reverse osmosis membrane is superior to concentration by evaporator from the viewpoint of reducing energy and costs, and is therefore preferably applied.

[0050] (Step E) The nanofiltration membrane permeate obtained in Step D is brought into contact with an extraction solvent that separates the aqueous solution into phase to obtain a 3-hydroxy-3,6-lactone extract. Extraction can be carried out by batch extraction, parallel flow multiple extraction, counterflow multi-stage extraction, etc. For continuous extraction on an industrial scale, a tower-type extraction apparatus such as a mixer-settler type extraction apparatus, a porous plate extraction column, a pulsating column, or a mixer-settler column can be used.

[0051] Next, the extraction solvent is removed from the recovered 3-hydroxyadipic acid-3,6-lactone extract. Common methods for removing the extraction solvent from the 3-hydroxyadipic acid-3,6-lactone extract include evaporating and concentrating the extraction solvent from the extract, separating the extraction solvent by solid-liquid separation after precipitating 3-hydroxyadipic acid-3,6-lactone from the extract, and separating 3-hydroxyadipic acid-3,6-lactone from the extraction solvent by contacting the extract with an aqueous solution, back-extracting 3-hydroxyadipic acid-3,6-lactone into the aqueous phase, and then separating the aqueous phase. The extraction solvent removed from the extract may be reused as is in the extraction process, or it may be purified by distillation before being reused. When purified by distillation, the amount of 3-hydroxyadipic acid-3,6-lactone recovered can be increased by recovering trace amounts of 3-hydroxyadipic acid-3,6-lactone contained in the extraction solvent.

[0052] (Step F) The purity of 3-hydroxyadipic acid-3,6-lactone recovered in Step E is further increased by distillation. In the distillation step, 3-hydroxyadipic acid-3,6-lactone is recovered from the vapor side, and at the same time, high-boiling point or low-volatility impurities are removed as distillation residue. The pressure conditions during distillation are preferably reduced pressure of 1 Pa or more and atmospheric pressure (normal pressure, about 101 kPa) or less, and more preferably reduced pressure of 100 Pa or more and 15 kPa or less. When performed under reduced pressure, the distillation temperature is preferably 20°C or more and 200°C or less, and more preferably 50°C or more and 180°C or less. The above distillation step may be batch or continuous. In addition, the 3-hydroxyadipic acid-3,6-lactone vaporized in the distillation apparatus is cooled and recovered by a condenser. Since the vapor phase contains low-boiling-point components such as water and organic solvents along with 3-hydroxyadipic acid-3,6-lactone, multiple condensers may be used, such as performing partial condensation in the first stage condenser to condense 3-hydroxyadipic acid-3,6-lactone and, if applicable, an arbitrary proportion of water, and then performing total condensation in the second stage condenser to condense the remaining water and low-boiling-point components.

[0053] (Step G) From the 3-hydroxyadipic acid-3,6-lactone obtained in Step F, an aqueous adipic acid solution is obtained based on the method described in International Publication No. 2021 / 060335 (e.g., Example 1). Specifically, the 3-hydroxyadipic acid-3,6-lactone is converted to adipic acid by carrying out a hydrogenation reaction in an aqueous solvent in the presence of a hydrogenation catalyst and hydrogen, thereby obtaining an aqueous adipic acid solution.

[0054] (Step H) After separating the catalyst from the adipic acid aqueous solution obtained in Step G by a normal separation operation such as solid-liquid separation, adipic acid crystals are recovered by the crystallization operation described above.

[0055] [Polyamides using adipic acid crystals as raw materials] The adipic acid crystals of the present invention can be suitably used as a raw material for polyamides composed of a diamine and adipic acid. As a method for producing polyamides using adipic acid crystals as raw materials, known methods of polycondensation of a diamine and adipic acid can be applied (see Fukumoto, Osamu (ed.), "Polyamide Resin Handbook," Nikkan Kogyo Shuppansha (January 1998) or Japanese Patent Publication No. 2004-75932). Specifically, by using 1,4-diaminobutane, 1,5-pentanediamine, and hexamethylenediamine as the diamine, polyamides 4, 6, polyamides 5, 6, and polyamides 6, 6 can be produced, respectively.

[0056] For example, polyamide 6,6 can be produced by pressurized heating polycondensation of hexamethylenediamine and adipic acid crystals of the present invention. Here, pressurized heating polycondensation is a method in which the raw materials, hexamethylenediamine and adipic acid salt, are heated in the presence of water to create a prepolymer by pressurizing the polymerization system with the generated water vapor, then the pressure is released to return to atmospheric pressure, the temperature inside the polymerization system is raised above the melting point of the resulting polymer, and then polycondensation is carried out by maintaining it at atmospheric pressure or reduced pressure.

[0057] In the melt polymerization of polyamides, a step is required to maintain a pressurized state within the polymerization system to generate a prepolymer, which is usually carried out in the presence of water. The amount of water added is preferably 10% to 70% by weight of the total amount of raw materials and water combined. If the amount of water is less than 10% by weight, the uniform dissolution of the nylon salt takes a long time, and excessive heat history tends to occur, which is undesirable. Conversely, if the amount of water is more than 70% by weight, a large amount of thermal energy is expended to remove the water, and it takes a long time to generate the prepolymer, which is also undesirable. Furthermore, the pressure used to maintain the pressurized state is 10 kg / cm². ２ More than 20kg / cm ２ The following is preferable: 10 kg / cm² ２ Maintaining a concentration below 20 kg / cm³ is undesirable because the diamine component is prone to volatilization outside the polymerization system. ２ To maintain a higher molecular weight, it is necessary to raise the temperature within the polymerization system, which is undesirable because it makes the diamine component more likely to volatilize out of the system.

[0058] In the polycondensation of polyamide under pressure and heat according to the present invention, in order to suppress the volatilization of diamine components and cyclization due to the deammonia reaction of diamine components, it is important to minimize the thermal history the polymer experiences throughout the polymerization process. As a means of achieving this, lowering the maximum temperature reached in the polymerization system is effective, but in order to obtain a polyamide with a high molecular weight, it is preferable to control the maximum temperature reached in the polymerization system to a specific temperature range. In the present invention, it is preferable to set the maximum temperature reached in the polymerization system to be above the melting point of the obtained polyamide and below 300°C, and more preferably between 270°C and 290°C. If the maximum temperature reached is below the melting point, the polymer precipitates in the polymerization system, and productivity is greatly reduced, which is undesirable. Furthermore, if the temperature is higher than 300°C, the volatilization and cyclization of diamine components are promoted, and the obtained polyamide tends to deteriorate.

[0059] Furthermore, in this invention, the time for which the polymerization system is held above the melting point of the polyamide under normal or reduced pressure affects the molecular weight of the resulting polyamide. Therefore, it is preferable to control the time for which the temperature inside the polymerization system is held above the melting point of the polyamide to 0.02 hours or more and 2 hours or less, and more preferably to 0.05 hours or more and 1 hour or less. If the time for holding above the melting point is less than 0.02 hours, the increase in molecular weight may be insufficient. Also, if the time for holding above the melting point is longer than 1 hour, the volatilization and cyclization of the diamine component may be promoted, and the resulting polyamide may deteriorate.

[0060] The polyamide of the present invention can also have its molecular weight increased by further solid-phase polymerization or by melt extrusion after pressurized and heated polycondensation. Solid-phase polymerization proceeds by heating in a vacuum or in an inert gas at a temperature range of 100°C to the melting point.

[0061] When producing the polyamide of the present invention, other components such as antioxidants and heat stabilizers (hindered phenols, hydroquinones, phosphates and their derivatives, copper halides, iodine compounds, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.), mold release agents and lubricants (aliphatic alcohols, aliphatic amides, aliphatic bisamides, bisurea and polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), dyes (nigrosine, aniline black, etc.), nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate anionic antistatic agents, quaternary ammonium salt cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agents, etc.), and flame retardants (melamine cyanide Flame retardants such as phosphates, hydroxides including magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.), fillers (particulate, fibrous, needle-shaped, and plate-shaped fillers such as graphite, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, antimony oxide, titanium dioxide, aluminum oxide, zinc oxide, iron oxide, zinc sulfide, zinc, lead, nickel, aluminum, copper, iron, stainless steel, glass fiber, carbon fiber, aramid fiber, bentonite, montmorillonite, synthetic mica, etc.), and other polymers (other polyamides, polyethylene, polypropylene, polyester, polycarbonate, polyphenylene ether, polyphenylene sulfide, liquid crystal polymer, polysulfone, polyethersulfone, ABS resin, SAN resin, polystyrene, etc.) can be added at any time.

[0062] Polyamide fibers can be produced by processing resin pellets made from polyamide with adipic acid as a raw material using known methods (for example, International Publication No. 2019 / 208427). The polyamide fibers thus obtained can be used in textile products for clothing, industrial materials, building and housing materials, or consumer goods. Specifically, they can be used in clothing applications such as innerwear, sportswear, and casual wear, as well as in industrial materials such as airbags and tire cords.

[0063] Furthermore, the resin pellets can be molded by known methods (for example, International Publication No. 2021 / 006257) to produce polyamide molded articles. The resulting polyamide molded articles can be used in resin products such as automotive parts, electrical and electronic components, machine parts, building and housing materials, various containers, daily necessities, household goods, and hygiene products.

[0064] The most distinctive feature of the polyamide of the present invention is that, by using adipic acid crystals with a boron content of 1 ppm to 1000 ppm as a raw material, or by using adipic acid crystals with a fluorescence intensity of 0.55 or higher as shown in formulas 1 to 3 above, the polymerization rate is improved compared to known polyamides made from petroleum-derived adipic acid. In the present invention, the improvement in polymerization rate was evaluated by comparing the number-average molecular weight or weight-average molecular weight when the reaction conditions such as temperature, pressure, and time during the polyamide polycondensation reaction were kept the same. This means that when polyamide polymerization is carried out under the same reaction conditions, those with a larger number-average molecular weight or weight-average molecular weight have a faster polymerization rate. When polyamide polymerization is carried out using the adipic acid crystals of the present invention as a raw material, the number-average molecular weight or weight-average molecular weight increases compared to when conventional petroleum-derived adipic acid is used, i.e., the polymerization rate improves. By producing polyamide using the adipic acid crystals of the present invention as a raw material, the polymerization time to reach the target molecular weight can be shortened, resulting in effects such as reduced energy input due to shortened heating time and increased polyamide production per unit time.

[0065] [Polyester made from adipic acid crystals] Polyester can be produced by polycondensation of the adipic acid crystals of the present invention with glycols by known methods (see, for example, "Research on Paints, vol. 151, pp. 2-8", Kansai Paint Co., Ltd. (November 2009)). Specifically, as glycols, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, etc. can be used. In this case, in addition to the adipic acid obtained in the present invention, it may be copolymerized with any dicarboxylic acid. Specifically, examples of dicarboxylic acids to be copolymerized include oxalic acid, malonic acid, succinic acid, glutaric acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 2,5-frandicarboxylic acid, etc. Here, by using 1,4-butanediol as the diol and terephthalic acid or succinic acid as the dicarboxylic acid, polybutylene adipate terephthalate (PBAT) and polybutylene succinate adipate (PBSA) can be obtained, respectively. These polyesters are biodegradable and therefore preferable from an environmental standpoint. Polybutylene adipate terephthalate (PBAT) and polybutylene succinate adipate (PBSA) can be produced by known methods (for example, Journal of Polymer Science: Part A: Polymer Chemistry, vol. 40, pp. 4141-4157 (2002) and International Publication No. 1996 / 019521). "Biodegradability" means the property of being broken down to the molecular level by the action of microorganisms and ultimately circulating back into nature as carbon dioxide and water.

[0066] Polyester resin pellets can be processed by known methods (e.g., International Publication No. 2007 / 037174) to produce polyester fibers. The polyester fibers thus obtained can be used for clothing, industrial materials, building and housing materials, or consumer goods. Specifically, they can be used in textile products such as woven fabrics, knitted fabrics, and nonwoven fabrics, as well as in clothing, fiber brushes, carpets, and the like.

[0067] Polyester resin pellets can be molded and processed by known methods (e.g., International Publication No. 2015 / 072216) to produce polyester molded articles. The resulting polyester molded articles can be used in automotive parts, electrical and electronic components, machine parts, building materials, various containers, daily necessities, household goods, and hygiene products. In addition, polyamide fibers can be produced in the same way as polyamide, and these can be used in clothing, industrial materials, building and housing materials, or household goods.

[0068] Polyester resin pellets can be stretched by known methods (e.g., International Publication No. 2010 / 038655) to produce a polyester film. The resulting polyester film can be used in film products for packaging, agricultural applications, electronic equipment, semiconductor products, electrical products, automotive parts, building materials, and more.

[0069] [Hexamethylenediamine Polyamide Using Adipic Acid as a Raw Material] The adipic acid crystals of the present invention can be suitably used as a raw material for hexamethylene. Known methods can be used to produce hexamethylenediamine using adipic acid crystals as a raw material (see, for example, Organic Synthesis Chemistry, Vol. 35, No. 6, 59-66 (1977)). Specifically, hexamethylenediamine can be produced by reacting adipic acid with ammonia, dehydrating with a dehydrating catalyst to produce adiponitrile, and then hydrogenating the adiponitrile.

[0070] One method for producing adiponitrile from adipic acid is to heat the adipic acid crystals of the present invention in the presence of ammonia using a dehydration catalyst such as phosphoric acid or silica gel. The reaction may be a liquid-phase reaction using a solvent or a gas-phase reaction in which adipic acid is vaporized and reacted. The resulting adiponitrile can be purified by known methods such as distillation and used in a subsequent hydrogenation reaction.

[0071] One method for producing hexamethylenediamine from adiponitrile is to heat adiponitrile in the presence of hydrogen using a common hydrogenation catalyst such as nickel or cobalt. The produced hexamethylenediamine can be purified by known methods such as distillation and can be suitably used as a polyamide raw material as described above.

[0072] The hexamethylenediamine obtained in the present invention can be suitably used as a raw material for polyamides composed of hexamethylenediamine and dicarboxylic acid. As a method for producing polyamides using hexamethylenediamine as a raw material, the known method of polycondensing the aforementioned diamine and adipic acid can be applied (see, for example, Fukumoto, Osamu (ed.), "Polyamide Resin Handbook," Nikkan Kogyo Publishing (January 1998) or Japanese Patent Publication No. 2004-75932). Specifically, by using adipic acid and sebacic acid as the dicarboxylic acid, polyamide 6,6 and polyamide 6,10 can be produced, respectively. Furthermore, by using adipic acid crystals derived from biomass resources in the present invention as the dicarboxylic acid raw material, polyamide 6,6 whose monomer is derived from biomass resources can be produced.

[0073] Polyamide fibers can be produced by processing resin pellets made from polyamide using hexamethylenediamine as a raw material using a known method (for example, International Publication No. 2019 / 208427). The polyamide fibers thus obtained can be used in textile products for clothing, industrial materials, building and housing materials, or consumer goods. Specifically, they can be used in clothing applications such as innerwear, sportswear, and casual wear, as well as industrial material applications such as airbags and tire cords.

[0074] Furthermore, the resin pellets can be molded by known methods (for example, International Publication No. 2021 / 006257) to produce polyamide molded articles. The resulting polyamide molded articles can be used in resin products such as automotive parts, electrical and electronic components, machine parts, building and housing materials, various containers, daily necessities, household goods, and hygiene products.

[0075] [ε-Caprolactam Polyamide 6 Using Adipic Acid Crystals as a Raw Material] The adipic acid crystals of the present invention can be suitably used as a raw material for ε-caprolactam. Known methods can be used to produce ε-caprolactam using adipic acid crystals as a raw material (see, for example, US No. 8946411 or International Publication No. 2012 / 141997). Specifically, ε-caprolactam can be produced by reacting the adipic acid crystals of the present invention with a metal catalyst such as Ru, Pt, or Pd in ​​the presence of hydrogen and ammonia. The resulting ε-caprolactam can be purified by known methods such as distillation and suitably used as a raw material for polyamide 6.

[0076] As a method for producing polyamide 6 by polymerizing ε-caprolactam obtained from the adipic acid crystals of the present invention as a raw material, known methods for ring-opening polymerization of ε-caprolactam can be applied (see, for example, Fukumoto, Osamu (ed.), "Polyamide Resin Handbook," Nikkan Kogyo Shuppansha (January 1998)).

[0077] Polyamide 6 fibers can be produced by processing resin pellets made from polyamide 6 raw materials using known methods. The resulting polyamide 6 fibers can be used in textile products for clothing, industrial materials, building and housing materials, or everyday life materials. Specifically, they can be used in clothing applications such as innerwear, sportswear, and casual wear, as well as in industrial materials such as airbags and tire cords.

[0078] Furthermore, the resin pellets can be molded using known methods to produce polyamide molded articles. The resulting polyamide 6 molded articles can be used in resin products such as automotive parts, electrical components, electronic components, mechanical parts, building and housing materials, various containers, daily necessities, household goods, and hygiene products.

[0079] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples.

[0080] The raw sugar was analyzed and quantified using HPLC analysis conditions 1 shown below. The 3-hydroxyadipic acid, 3-hydroxyadipic acid-3,6-lactone, and adipic acid were analyzed and quantified using HPLC analysis conditions 2 shown below. The raw materials and products were quantified using absolute calibration curves prepared using standards.

[0081] [HPLC Analysis Conditions 1] HPLC instrument: "Prominence" (Shimadzu Corporation) Column: Shodex Sugar series SH1011 (Resonac) Mobile phase: 5 mM sulfuric acid aqueous solution Flow rate: 0.6 mL / min Detector: Refractometer (RI) Column temperature: 65°C.

[0082] [HPLC Analysis Conditions 2] HPLC instrument: "Prominence" (Shimadzu Corporation) Column: "Synergi Polar-RP" (Phenomenex), length 250 mm, inner diameter 4.60 mm, particle size 4 μm + "Synergi hydro-RP" (Phenomenex), length 250 mm, inner diameter 4.60 mm, particle size 4 μm Mobile phase: 5 mM formic acid aqueous solution / acetonitrile = 98 / 2 (volume ratio) Reaction solution: 5 mM formic acid + 20 mM Bis-Tris + 0.1 mM EDTA-2Na aqueous solution / acetonitrile = 98 / 2 (volume ratio) Flow rate: 1.0 mL / min Detector: Electrical conductivity detector (CDD) Column temperature: 45°C.

[0083] [Analysis Conditions for Boron Compounds] Adipic acid crystals were weighed into a fluororesin container, nitric acid was added, and acid decomposition was performed using a microwave sample pretreatment method. Ultrapure water was added to the resulting treatment solution to obtain a fixed volume solution, and the amount of boron element in the fixed volume solution was quantified using an ICP mass spectrometer. Microwave sample pretreatment device: "ETHOS 1" (Milestone) ICP mass spectrometer: "Agilent 8800" (Agilent Technologies).

[0084] The fluorescence intensity of adipic acid crystals was determined using a fluorescence analyzer under the following analytical conditions. With both the excitation and observation side slit widths set to 3 nm, the fluorescence intensity at excitation wavelengths of 300–340 nm (at 5 nm intervals) and 400–436 nm (at 2 nm intervals) was measured, as well as the scattering intensity at excitation wavelength of 340 nm and 378–382 nm (at 2 nm intervals). The fluorescence intensity of the adipic acid crystals was then calculated according to equations 1 to 3 described above.

[0085] [Fluorescence Analysis Conditions] Fluorescence analyzer: "Fluorolog 3-22" (Horiba Jobin Yvon) Light source: Xenon lamp Detector: PMT Excitation wavelength: 250 nm to 700 nm (5 nm intervals) Observation wavelength (fluorescence wavelength): up to 750 nm (2 nm intervals) Slit width: 3 nm on the excitation side, 3 nm on the observation side Time constant: 0.1 s Measurement mode: Sc / Rc.

[0086] The number-average molecular weight of polyamides was determined using gel permeation chromatography (GPC) under the conditions described below. The number-average molecular weight (Mn) was expressed as a value equivalent to standard polymethyl methacrylate.

[0087] The weight-average molecular weight of polyamides was determined using gel permeation chromatography (GPC) under the following conditions. The weight-average molecular weight (Mw) was expressed on a standard polymethyl methacrylate basis.

[0088] [Molecular Weight Analysis Conditions] Pump: “e-Alliance GPC system” (Waters) Detector: Differential refractometer “Waters 2414” (Waters) Column: “Shodex HFIP-806M” (2) + “HFIP-LG” (Shodex) Mobile phase: Hexafluoroisopropanol (with 0.005N sodium trifluoroacetate added) Flow rate: 1 mL / min Sample concentration: Approximately 2.5 mg of polyamide dissolved in 4 mL of mobile phase Temperature: 30°C Injection volume: 0.1 mL.

[0089] [Polyamide 6,6 Polymerization Test] The polyamide 6,6 raw materials prepared in Comparative Example 1 and Examples 1-3 were each placed in test tubes. The prepared test tubes were then placed together in an autoclave, sealed, and purged with nitrogen. Next, the heater temperature was set to 285°C and heating was started. The internal pressure of the autoclave was 17.5 kg / cm². ２ After reaching this point, the internal pressure of the can is set to 17.5 kg / cm². ２ The mixture was held in this state for two hours. Then, the pressure inside the can was gradually returned to atmospheric pressure over 1.5 hours, and heating was stopped when the temperature inside the can reached 275°C. After cooling to room temperature, the test tube was removed from the autoclave to obtain polyamide 6,6.

[0090] (Comparative Example 1) Preparation of polyamide 6,6 using petroleum-derived adipic acid crystals as raw material 20 g of a 50 wt% aqueous solution of equimolar salts of hexamethylenediamine (Kanto Chemical, purity > 98.0%) and petroleum-derived adipic acid (Fujifilm Wako Pure Chemical Industries, adipic acid content 99.5 wt%) was used as the raw material for polyamide 6,6 and subjected to the polyamide 6,6 polymerization test described above. The results of the boron compound analysis of the petroleum-derived adipic acid crystals and the number-average molecular weight analysis of polyamide 6,6 are shown in Table 1.

[0091] (Reference Example 1) Preparation of adipic acid aqueous solution using reagent glucose as raw material Using reagent glucose (manufactured by San-ei Sugar Refining Co., Ltd.) as the sugar raw material, 8 L of 3-hydroxyadipic acid ferment broth was prepared according to the method using the EcΔGPPR / 3HA strain described in Example 10 of International Publication No. 2022 / 102635. Analysis of the supernatant by HPLC showed a 3-hydroxyadipic acid concentration of 8.1 g / L.

[0092] In preparing 3-hydroxyadipic acid-3,6-lactone from the above-mentioned 3-hydroxyadipic acid fermentation broth, the method described in Example 3 of International Publication No. 2020 / 196459 was followed. Specifically, 8 L of the 3-hydroxyadipic acid fermentation broth was passed through a microfiltration membrane (porous membrane with pore size of 0.01 μm or more and less than 1 μm: manufactured by Toray Industries, Inc.), and the permeate from the microfiltration membrane was passed through an ultrafiltration membrane (molecular weight cutoff 10000: manufactured by Toray Industries, Inc.) to collect the permeate. Concentrated sulfuric acid (manufactured by Sigma-Aldrich) was added to the obtained aqueous solution to adjust the pH to 2.5, and the mixture was stirred for 12 hours. 7.5 L of the resulting 3-hydroxyadipic acid-3,6-lactone aqueous solution was passed through a nanofiltration membrane under the following nanofiltration membrane treatment conditions to obtain a filtrate (3-hydroxyadipic acid-3,6-lactone concentration 5.4 g / L).

[0093] [Nanofiltration membrane processing conditions] Separation membrane: UTC-63 (Toray) Membrane separation device: "SEPA" (registered trademark) CF-II (GE W&PT) Operating temperature: 25℃ Filtration pressure: 2MPa.

[0094] Next, the permeate from the nanofiltration membrane was concentrated using a rotary evaporator (Tokyo Rikakikai) to obtain 90 mL of concentrated 3-hydroxyadipic acid-3,6-lactone. This aqueous solution containing 3-hydroxyadipic acid-3,6-lactone was transferred to a glass separatory funnel (capacity 300 mL), 30 mL of ethyl acetate (Fujifilm Wako Pure Chemical Industries) was added, and after shaking, the ethyl acetate phase was collected. The same procedure was repeated to extract 3-hydroxyadipic acid-3,6-lactone using a total of 90 mL of ethyl acetate. The 3-hydroxyadipic acid-3,6-lactone extract obtained by collecting the ethyl acetate phase was concentrated using a rotary evaporator to remove the ethyl acetate, the extraction solvent, and obtain 34.6 g of pale yellow syrup-like 3-hydroxyadipic acid-3,6-lactone.

[0095] Next, 3-hydroxyadipic acid-3,6-lactone was subjected to vacuum distillation at 0.7 kPa and 160°C to obtain 27.9 g of 3-hydroxyadipic acid-3,6-lactone.

[0096] In preparing an aqueous solution of adipic acid from 3-hydroxyadipic acid-3,6-lactone, the method described in Example 1 of International Publication No. 2021 / 060335 was followed. Into a stainless-steel autoclave (pressure-resistant glass industry) with an internal volume of 0.1 L, 3 g of distilled 3-hydroxyadipic acid-3,6-lactone, 30 mL of water, and 0.075 g of Palladium, 5% on gamma alumina powder, reduced (5% Pd / Al ２ O ３ , Alfa Aesar) were added. After purging the inside of the autoclave with nitrogen, hydrogen gas was added, and the hydrogen partial pressure inside the autoclave was adjusted to 0.9 MPa. Then, the temperature inside the autoclave was raised to 170 °C. The gauge pressure at 170 °C was 1.2 MPa. After holding at 170 °C for 8 hours, it was allowed to cool to 60 °C, the gas inside the autoclave was released to return to normal pressure, and then the reaction solution was recovered. The reaction solution kept at 60 °C was filtered to remove the catalyst, a part of the aqueous adipic acid solution was collected, diluted with water and analyzed by HPLC. As a result, the adipic acid concentration was 91.3 g / L.

[0097] (Example 1) Preparation of Adipic Acid Crystals and Polyamide 6,6 Using Glucose as a Raw Material 0.12 L of the aqueous adipic acid solution prepared in Reference Example 1 (equivalent to 4 times the hydrogenation reaction) was heated to 60 °C to completely dissolve adipic acid, and then water was removed by an evaporator while heating to 80 °C to concentrate adipic acid (adipic acid concentration: about 33% by weight). After the concentrated solution was gradually cooled to room temperature, it was left standing at 4 °C overnight to crystallize adipic acid, recovered by solid-liquid separation, and then dried at 110 °C overnight to obtain 9.1 g of adipic acid crystals (adipic acid content: 99.8% by weight). Table 1 shows the results of the analysis of boron compounds in the obtained adipic acid crystals.

[0098] Subsequently, except using the above adipic acid crystals as a raw material, a polyamide 6,6 raw material was prepared in the same manner as in Comparative Example 1 and subjected to the above polyamide 6,6 polymerization test. Table 1 shows the results of the analysis of the number-average molecular weight of polyamide 6,6 polymerized using adipic acid crystals prepared from reagent glucose as a raw material.

[0099] (Reference Example 2) Preparation of an aqueous adipic acid solution using cellulose-containing biomass saccharification liquid as a raw material. 5 L of sugar solution was prepared according to the method described in Example 1 of International Publication No. 2024 / 009922. The glucose concentration of the sugar solution was analyzed by HPLC and found to be 120 g / L. Using this sugar solution as a raw material, 8 L of 3-hydroxyadipic acid fermentation liquid was prepared in the same manner as in Reference Example 1. The supernatant was analyzed by HPLC and found to have a 3-hydroxyadipic acid concentration of 7.9 g / L. Thereafter, an aqueous adipic acid solution was prepared from the 3-hydroxyadipic acid fermentation liquid using the same method as in Reference Example 1 (adipic acid concentration 90.6 g / L).

[0100] (Example 2) Preparation of adipic acid crystals and polyamide 6,6 using cellulose-containing biomass saccharification liquid as raw material Using 0.12 L of adipic acid aqueous solution obtained in Reference Example 2 (equivalent to 4 hydrogenation reactions), concentration and crystallization were carried out using an evaporator in the same manner as in Example 1 to obtain 8.9 g of adipic acid crystals (adipic acid content 99.7% by weight). The results of the boron compound analysis of the obtained adipic acid crystals are shown in Table 1.

[0101] Next, polyamide 6,6 raw materials were prepared in the same manner as in Comparative Example 1, except that the above-mentioned adipic acid crystals were used as raw materials, and subjected to the polyamide 6,6 polymerization test described above. Table 1 shows the number-average molecular weight analysis results of polyamide 6,6 polymerized using adipic acid crystals made from cellulose-containing biomass saccharification liquid as a raw material.

[0102] (Example 3) Preparation of adipic acid crystals and polyamide 6,6 using cellulose-containing biomass saccharification liquid as raw material Adipic acid crystals were prepared in the same manner as in Examples 1 and 2, except that the adipic acid aqueous solution obtained in Reference Example 2 was crystallized twice. For the second crystallization, pure water was added to the adipic acid crystals obtained in the first crystallization (adipic acid concentration of approximately 33% by weight), and after heating to 80°C to completely dissolve the adipic acid, crystallization of adipic acid was carried out again to obtain 8.5 g of second-order adipic acid crystals (adipic acid content of 99.9% by weight). The results of the boron compound analysis of the obtained adipic acid crystals are shown in Table 1.

[0103] Next, polyamide 6,6 raw materials were prepared in the same manner as in Comparative Example 1, except that the above-mentioned adipic acid crystals were used as raw materials, and subjected to the polyamide 6,6 polymerization test described above. Table 1 shows the number-average molecular weight analysis results of polyamide 6,6 polymerized using adipic acid crystals (second-order crystals) made from cellulose-containing biomass saccharification liquid as a raw material.

[0104]

[0105] (Comparative Example 2) Preparation of polyamide 6,6 using petroleum-derived adipic acid crystals as raw material A polymerization test of polyamide 6,6 was performed using the same method as in Comparative Example 1. The fluorescence analysis results of petroleum-derived adipic acid crystals and the weight-average molecular weight analysis results of polyamide 6,6 are shown in Table 2.

[0106] (Example 4) Preparation of adipic acid crystals and polyamide 6,6 using glucose as a raw material 9.1 g of adipic acid crystals (adipic acid content 99.8% by weight) were obtained by the same method as in Example 1. The results of fluorescence analysis of the obtained adipic acid crystals are shown in Table 2.

[0107] Next, polyamide 6,6 raw materials were prepared in the same manner as in Comparative Example 1, except that the above-mentioned adipic acid crystals were used as raw materials, and subjected to the polyamide 6,6 polymerization test described above. Table 2 shows the weight-average molecular weight analysis results of polyamide 6,6 polymerized using adipic acid crystals prepared from reagent glucose.

[0108] (Example 5) Preparation of adipic acid crystals and polyamide 6,6 using cellulose-containing biomass saccharification liquid as raw material Using the same method as in Example 2, 8.9 g of adipic acid crystals (adipic acid content 99.7% by weight) were obtained. The results of fluorescence analysis of the obtained adipic acid crystals are shown in Table 2.

[0109] Next, polyamide 6,6 raw materials were prepared in the same manner as in Comparative Example 1, except that the above-mentioned adipic acid crystals were used as raw materials, and subjected to the polyamide 6,6 polymerization test described above. The weight-average molecular weight of polyamide 6,6 polymerized using adipic acid crystals made from cellulose-containing biomass saccharification liquid is shown in Table 2.

[0110] (Example 6) Preparation of adipic acid crystals and polyamide 6,6 using cellulose-containing biomass saccharification liquid as raw material Using the same method as in Example 3, 8.5 g of second-order adipic acid crystals (adipic acid content 99.9% by weight) were obtained. The results of fluorescence analysis of the obtained adipic acid crystals are shown in Table 2.

[0111] Next, polyamide 6,6 raw materials were prepared in the same manner as in Comparative Example 1, except that the above-mentioned adipic acid crystals were used as raw materials, and subjected to the polyamide 6,6 polymerization test described above. Table 2 shows the results of analyzing the weight-average molecular weight of polyamide 6,6 polymerized using adipic acid crystals (second-order crystals) derived from cellulose-containing biomass saccharification liquid as a raw material.

[0112]

Claims

1. Adipic acid crystals containing adipic acid derived from biomass resources.

2. The adipic acid crystal according to claim 1, wherein the biomass is cellulose-containing biomass.

3. Adipic acid crystals containing a boron compound, wherein the boron content is 1 ppm or more and 1000 ppm or less.

4. An adipic acid crystal containing fluorescent impurities, wherein when fluorescence is measured with both the excitation and observation slit widths set to 3 nm, the fluorescence intensity of the adipic acid crystal calculated by the following equations 1 to 3 is 0.55 or higher. (Equation 1) Fluorescence intensity A = {Sum of fluorescence intensities from 400 to 436 nm (every 2 nm) at excitation wavelengths of 300 to 340 nm (every 5 nm)} / 171 (Equation 2) Scattering intensity B (Raman scattering intensity) = {Sum of scattering intensities from 378 to 382 nm (every 2 nm) at excitation wavelength of 340 nm} / 3 (Equation 3) Fluorescence intensity of adipic acid crystal = Fluorescence intensity A / Scattering intensity B 5. The adipic acid crystal according to claim 3 or 4, wherein the boron compound or the fluorescent impurity is an impurity derived from biomass resources.

6. The adipic acid crystal according to claim 3 or 4, wherein the boron compound or the fluorescent impurity is an impurity contained in adipic acid obtained by chemical synthesis from a hydroxycarboxylic acid or unsaturated dicarboxylic acid having six carbon atoms derived from biomass resources or a derivative thereof.

7. The adipic acid crystal according to claim 6, wherein the impurity is an impurity contained in adipic acid obtained by chemical synthesis from 3-hydroxyadipic acid or its derivatives derived from biomass resources.

8. The adipic acid crystal according to claim 6, wherein the impurity is an impurity contained in adipic acid obtained by microbial fermentation using carbohydrates derived from biomass resources as raw material.

9. The adipic acid crystal according to claim 3 or 4, wherein the adipic acid crystal is obtained by crystallizing an adipic acid-containing solution.

10. The adipic acid crystal according to claim 9, wherein the crystallization step includes a step of crystallizing an adipic acid-containing solution, a step of solid-liquid separation of adipic acid crystals and mother liquor, and a step of circulating the mother liquor back to the crystallization step.

11. The adipic acid crystal according to claim 3 or 4, wherein the adipic acid is a free form of adipic acid.

12. The adipic acid crystal according to claim 3 or 4, wherein the adipic acid content in the crystal is 99% by weight or more.

13. A method for producing adiponitrile, comprising the step of dehydrating adipic acid crystals according to claim 3 or 4 in the presence of ammonia.

14. A method for producing hexamethylenediamine, comprising the step of hydrogenating adiponitrile obtained by the method of claim 13.

15. A method for producing ε-caprolactam, comprising the step of reacting the adipic acid crystals described in claim 3 or 4 with hydrogen and ammonia in the presence of a catalyst.

16. A polyamide comprising adipic acid crystals and a diamine as raw materials according to claim 3 or 4.

17. The polyamide according to claim 16, wherein the diamine is 1,4-butanediamine, 1,5-pentanediamine, or hexamethylenediamine.

18. The polyamide according to claim 17, wherein the polyamide is polyamide 4,6, polyamide 5,6, or polyamide 6,6.

19. A polyamide made from hexamethylenediamine and a dicarboxylic acid obtained by the method of claim 14.

20. The polyamide according to claim 19, wherein the dicarboxylic acid is adipic acid or sebacic acid.

21. The polyamide according to claim 19, wherein the dicarboxylic acid raw material is the adipic acid crystal according to claim 3 or 4.

22. The polyamide according to claim 20, wherein the polyamide is polyamide 6,6 or polyamide 6,10.

23. A polyamide 6 made from ε-caprolactam obtained by the method described in claim 15.

24. A polyester made from adipic acid crystals and glycols as raw materials according to claim 3 or 4.

25. The polyester according to claim 24, wherein the glycol is 1,4-butanediol.

26. The polyester according to claim 25, wherein the polyester is polybutylene adipate terephthalate or polybutylene succinate adipate.

27. Resin pellets made from polyamide as described in claim 16.

28. Resin pellets made from polyamide as described in claim 19.

29. Resin pellets made from polyamide 6 as described in claim 23.

30. Resin pellets made from polyester as described in claim 24.

31. A fiber obtained by processing the resin pellets according to any one of claims 27 to 30.

32. A textile product made using the fibers described in claim 31.

33. The textile product according to claim 32, wherein the textile product is clothing, industrial material, building / housing material, or living material.

34. A molded article obtained by processing a resin pellet according to any one of claims 27 to 30.

35. The molded article according to claim 34, wherein the molded article is an electrical or electronic equipment component, an automobile component, a machine component, or a building or housing material.

36. A polyester film obtained by processing the resin pellets of claim 30.

37. A film product made using the polyester film described in claim 36.

38. The film product according to claim 37, wherein the film product is a film for packaging materials or an agricultural film.

Images