Extraction process of long-chain dicarboxylic acid and long-chain dicarboxylic acid product

Abstract

The invention provides an extraction process of long-chain dicarboxylic acid. The extraction process comprises the following steps: (1) carrying out extraction treatment on a material containing the long-chain dicarboxylic acid; the extraction treatment comprises the following steps: mixing the material containing the long-chain dicarboxylic acid with an organic mixed solvent to obtain a first mixture; the first mixture is subjected to heat preservation stirring treatment at the temperature of 50-120 DEG C, then standing layering is conducted, an extraction phase is separated, and a second mixture is obtained; (2) recovering the long-chain dicarboxylic acid from the second mixture; wherein the organic mixed solvent comprises any two or a combination of more than two of an ester compound, an organic acid compound, an alcohol compound, an ether compound, a sulfoxide compound, halogenated alkane, a hydrocarbon compound and a petroleum product. Compared with the traditional process, the extraction process of the long-chain dibasic acid in one embodiment of the invention has the advantages that the long-chain dibasic acid can be separated from most of impurities such as pigments and the like without using a large amount of acid, alkali or activated carbon. And the obtained product has high purity.

Description

Technical Field

[0001] The invention relates to a method for extracting and refining a long-chain dibasic acid prepared by a biological fermentation method, in particular to a solvent extraction process for the long-chain dibasic acid. Background Art

[0002] Long chain dicarboxylic acids refer to aliphatic dicarboxylic acids (DCn for short) with more than 10 carbon atoms in the carbon chain, including saturated and unsaturated dicarboxylic acids. They are a kind of fine chemical products with important and extensive industrial applications. They are important basic raw materials for synthesizing advanced fragrances, high-performance nylon engineering plastics, high-grade nylon hot melt adhesives, high-temperature dielectrics, advanced paints and coatings, advanced lubricants, cold-resistant plasticizers, resins, medicines and pesticides in the chemical industry. Due to the broad development potential of downstream products of long chain dicarboxylic acids, the demand for long chain dicarboxylic acids at home and abroad will continue to increase, and its market potential is huge.

[0003] The biological method (fermentation method) to produce long-chain dibasic acids is the application of microbial technology in the field of petrochemicals that emerged in the 1970s. Its characteristics are that it uses abundant petroleum resources as raw materials, utilizes the unique oxidation ability of microorganisms and the action of microbial intracellular enzymes, and oxidizes the two methyl groups at both ends of long-chain normal alkanes to carboxyl groups at room temperature and pressure to generate various long-chain dibasic acids of corresponding chain lengths; the biological method of producing long-chain dibasic acids overcomes the various shortcomings of simple chemical synthesis methods and vegetable oil cracking methods, and opens up a new way for the mass production of long-chain dibasic acids. Compared with chemical synthesis methods, the biological method of producing long carbon chain dibasic acids has unquestionable advantages and is widely valued at home and abroad. The biological method can not only provide a series of long carbon chain dibasic acid monomers from C9 to C18 and even C22, but also produce long-chain dibasic acids that cannot be produced by chemical synthesis (such as long-chain dibasic acids above C13), which greatly expands the application of dibasic acids in the industrial field.

[0004] The biological method for preparing long-chain dibasic acids has mild conditions and simple processes. However, in addition to dibasic acids, the fermentation broth also contains a large amount of bacteria, organic matter such as protein and pigments. The extraction and refining process is complex, the cycle is long, and the equipment investment is large.

[0005] Patent application CN1255483A (published on June 7, 2000) uses a long-chain dibasic acid monosalt crystallization process to reduce the content of impurities such as protein and pigment in the product, and prepares a long-chain dibasic acid product with a total acid content of more than 99% and a white appearance. This method requires repeated acidification, poor monosalt crystallization properties, and engineering problems such as fine particles, difficulty in filtering, and difficulty in washing, and requires high precision in operation; and the monosalt has a large solubility and a low yield of dibasic acid.

[0006] Patent application CN1351006A (published on May 29, 2002) uses a process of one-time acidification and one-time melting decolorization to reduce the content of impurities such as protein and organic pigments in the product. The adsorbents used are activated carbon, activated clay, etc. This method requires melting the crude dibasic acid, which is prone to Maillard reaction at high temperature, causing the reducing group to react, affecting the product, and the product yield is low. The melting energy consumption is high, and it is not suitable for industrial production.

[0007] Patent application CN102010318A (published on April 13, 2011) uses a method of decolorizing twice or more times and then acidifying in the aqueous phase to remove some pigments and improve the purity of the mixed dibasic acid. The disadvantage is that the process requires two or more activated carbon decolorizations, resulting in a large loss of dibasic acid, low yield, and high cost. Summary of the invention

[0008] A main purpose of the present invention is to provide a long-chain dibasic acid extraction process, comprising the following steps:

[0009] (1) extracting a material containing a long-chain dibasic acid; the extraction process comprising:

[0010] Mixing the material containing the long-chain dibasic acid with an organic mixed solvent to obtain a first mixture; and

[0011] The first mixture is subjected to a heat preservation and stirring treatment at 50 to 120° C., and then allowed to stand for stratification, and the extract phase is separated to obtain a second mixture;

[0012] (2) recovering the long-chain dibasic acid from the second mixture;

[0013] The organic mixed solvent includes any two or more of ester compounds, organic acid compounds, alcohol compounds, ether compounds, sulfoxide compounds, halogenated alkanes, hydrocarbon compounds, and petroleum products, and the hydrocarbon compounds include alkanes and / or aromatic hydrocarbons.

[0014] One embodiment of the present invention provides a long-chain dibasic acid product, wherein the long-chain dibasic acid content is ≥80wt%, the light transmittance of the long-chain dibasic acid product is ≥70%, and the solvent residue of the long-chain dibasic acid product is <800ppm.

[0015] The extraction process of the long-chain dibasic acid in one embodiment of the present invention uses an organic mixed solvent to extract the material containing the long-chain dibasic acid. Compared with the traditional process, it avoids a large amount of acid, alkali or activated carbon, and can achieve the separation of the long-chain dibasic acid from most impurities such as pigments. The obtained product has high purity. DETAILED DESCRIPTION

[0016] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions therein are essentially used as illustrations rather than to limit the present invention.

[0017] An embodiment of the present invention provides a long-chain dibasic acid extraction and purification process, comprising the following steps:

[0018] (1) extracting a material containing a long-chain dibasic acid; the extraction process comprises:

[0019] Mixing a material containing a long-chain dibasic acid with an organic mixed solvent to obtain a first mixture;

[0020] The first mixture is heated to 50-120° C., stirred and kept at 50-120° C., and then allowed to stand for stratification to obtain a second mixture (extract phase);

[0021] (2) Recovering the long-chain dibasic acid from the second mixture.

[0022] In one embodiment, the extraction process is solid-liquid extraction.

[0023] In one embodiment, step (1) comprises heating a mixture of a material containing a long-chain dibasic acid and an organic mixed solvent to 50-120° C. under stirring conditions.

[0024] In one embodiment, the mass of the organic mixed solvent in the second mixture accounts for more than 60 wt % of the mass of the organic mixed solvent raw material initially charged.

[0025] In one embodiment, an extract phase and a raffinate phase are formed by selecting a suitable extractant, and then the extract phase is separated to separate the long-chain dibasic acid from the impurities.

[0026] In one embodiment, the long-chain dibasic acid includes any one or a combination of linear azelaic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedicarboxylic acid or 9-ene-octadecanedicarboxylic acid.

[0027] In one embodiment, the material containing long-chain dibasic acid includes one or more of crude long-chain dibasic acid, residue after solvent recovery from recrystallization mother liquor of crude long-chain dibasic acid, precipitate rich in long-chain dibasic acid recovered from a sewage treatment workshop, and slurry of other long-chain dibasic acids.

[0028] In one embodiment, the crude long-chain dibasic acid is obtained by acidifying the fermentation broth of the long-chain dibasic acid with or without bacterial separation, adding acid (such as sulfuric acid, hydrochloric acid, etc.) and filtering crystals.

[0029] In one embodiment, the crude long-chain dibasic acid contains a small amount of impurities such as water, fermentation substrate residues, salts, bacteria and pigments.

[0030] In one embodiment, after the crude long-chain dicarboxylic acid product is crystallized from a solvent, most of the miscellaneous acids (including miscellaneous acids produced as byproducts during the fermentation process, such as monoacids, diacids with carbon chain lengths different from those of the fermentation substrate, etc.) and most of the other impurities (including pigments, sugars, inorganic salts, cell tissues of fermenting microorganisms, proteins, etc.) are dissolved in the solvent and separated from the main long-chain dicarboxylic acids in the crude long-chain dicarboxylic acid product. Since the recrystallization process adopts a method of first dissolving the crude long-chain dicarboxylic acid product in a solvent and then cooling and crystallizing, part of the long-chain dicarboxylic acid is still dissolved in the solvent mother liquor after the crystals are separated. After the solvent mother liquor is passed through a distillation tower or a rectification tower to recover most of the solvent, the remaining bottom material still contains long-chain dicarboxylic acids.

[0031] The present invention does not particularly limit the content of long-chain dibasic acid in the material containing long-chain dibasic acid, and can be 10-99wt%, and further can be 10-85wt%, for example, 20wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 70wt%, 75wt%, 80wt% and the like.

[0032] In one embodiment, the material containing the long-chain dibasic acid may contain a certain amount of water, with the water content being ≤50 wt %, preferably ≤20 wt %, and more preferably ≤10 wt %.

[0033] In one embodiment, the organic mixed solvent includes a combination of any two, three or more of ester compounds, organic acid compounds, alcohol compounds, ether compounds, sulfoxide compounds, halogenated alkanes, hydrocarbon compounds and petroleum products.

[0034] In one embodiment, the ester compounds include but are not limited to phosphorus-oxygen type ester compounds, fatty acid ester compounds with 1 to 10 carbon atoms, and further with 1 to 4 carbon atoms. For example, they may include one or a combination of two or more of di(2-ethylhexyl) phosphate (P204), ethyl acetate, butyl acetate, and methyl acetate.

[0035] In one embodiment, the organic acid compound includes, but is not limited to, one or a combination of two or more fatty acids having carbon atoms of 1 to 5, and further includes one or a combination of two or more fatty acids having carbon atoms of 1 to 4. The fatty acid includes fatty monobasic acid and / or fatty dibasic acid, and further includes any one or a combination of two or more of formic acid, acetic acid, propionic acid, and butyric acid.

[0036] In one embodiment, the density of the organic acid compound is 0.9 to 1.3 g / cm 3 , further 0.95~1.25g / cm 3 .

[0037] In one embodiment, the alcohol compound can be one or more of a monohydric alcohol and a polyhydric alcohol, and the carbon atoms of the alcohol compound can be 1 to 5, for example, any one of methanol, ethanol, propanol, butanol, isopropanol, and ethylene glycol, or a combination of two or more thereof.

[0038] In one embodiment, the hydrocarbon compound includes alkanes and / or aromatic hydrocarbons, and the alkanes may include chain alkanes and / or cycloalkanes.

[0039] In one embodiment, the alkane includes, but is not limited to, straight-chain or branched alkanes, cycloalkanes, or combinations thereof having 5 to 23 carbon atoms; and further includes any one of pentane, hexane, heptane, octane, decane, n-undecane, n-dodecane, n-tridecane, and n-hexadecane, or a combination of two or more thereof.

[0040] In one embodiment, the number of carbon atoms contained in the aromatic hydrocarbon may be 6 to 10, including but not limited to any one of benzene, toluene, ethylbenzene, and xylene, or a combination of two or more thereof.

[0041] In one embodiment, the petroleum product includes, for example, gasoline and / or kerosene.

[0042] In one embodiment, the sulfoxide compound includes but is not limited to dimethyl sulfoxide.

[0043] In one embodiment, the halogenated alkane includes halogenated alkane having 1 to 3 carbon atoms, further including but not limited to one, two or three of chloroform, carbon tetrachloride and dichloromethane.

[0044] In one embodiment, the ether compound includes but is not limited to diethyl ether.

[0045] In one embodiment, the organic mixed solvent includes at least a first solvent, and the first solvent includes hydrocarbon compounds, petroleum products or a combination thereof. Further, the first solvent includes one or more alkanes with 5 to 23 carbon atoms.

[0046] In one embodiment, the organic mixed solvent includes more than 50 wt %, further includes more than 80 wt % of the first solvent, further includes 80-97 wt % of the first solvent, for example, includes 85 wt %, 90 wt % or 95 wt % of the first solvent.

[0047] In one embodiment, the organic mixed solvent includes a second solvent, and the second solvent includes one, two or more of an ester compound, an organic acid compound, an alcohol compound, an ether compound, a sulfoxide compound, and a halogenated alkane.

[0048] In one embodiment, the second solvent includes: one or a combination of P204, formic acid, acetic acid, propionic acid, butyric acid, methanol, ethanol, propanol, butanol, isopropanol, dimethyl sulfoxide, ether, petroleum ether, ethyl acetate, butyl acetate, methyl acetate, carbon tetrachloride, dichloromethane, and chloroform.

[0049] In one embodiment, the first solvent and the second solvent are different.

[0050] In one embodiment, the organic mixed solvent comprises a first solvent and a second solvent, and the mass ratio of the first solvent to the second solvent can be (1-200):1, further (1-100):1, further (1-50):1, further (1-30):1, for example 4:1, 9:1, 15:1, 25:1, 97:3, 40:1, 70:1.

[0051] In one embodiment, the organic mixed solvent includes 80-97 wt % of the first solvent and 3-20 wt % of the first solvent, for example, 5 wt %, 10 wt %, or 15 wt % of the first solvent.

[0052] In one embodiment, the organic mixed solvent includes the following solvent combinations in mass ratios: 20wt% acetic acid and 80wt% kerosene; or 20wt% ethyl acetate and 80wt% kerosene; or 10wt% acetic acid, 10wt% butanol and 80wt% decane; or 20wt% n-butanol and 80wt% n-tridecane; or 20wt% formic acid and 80wt% kerosene; or 10wt% butanol and 90wt% n-tridecane; or 10wt% butyric acid and 90wt% decane; or 10wt% butyric acid and 90wt% n-dodecane; or 3% acetic acid and 97% kerosene.

[0053] In one embodiment, a material containing a long-chain dibasic acid and an organic mixed solvent are mixed under heating conditions. After standing for phase separation, the long-chain dibasic acid component and the impurity component are redistributed in the extract phase and the raffinate phase, the long-chain dibasic acid is enriched in the extract phase, and the impurities remain in the raffinate phase. By separating the extract phase, the long-chain dibasic acid is separated and thus separated from the impurities.

[0054] In one embodiment, after standing for phase separation, the extract phase is located at the top and the raffinate phase is located at the bottom.

[0055] In one embodiment, in step (1), after mixing the material containing the long-chain dibasic acid with the organic mixed solvent, the mixture is stirred while being heated to 50-120°C.

[0056] In one embodiment, the insulation temperature of step (1) can be 50-120°C, further 70-100°C, for example 60°C, 75°C, 80°C, 85°C, 90°C, 95°C, 105°C, 110°C, etc.

[0057] In one embodiment, the extraction treatment in step (1) is carried out in a sealed pressurized container.

[0058] In one embodiment, multi-stage extraction is performed according to the condition parameters of step (1). The total yield of the multi-stage extraction can reach more than 95%.

[0059] In one embodiment, in step (1), the material containing the long-chain dibasic acid and the organic mixed solvent may be fully mixed by stirring to obtain a first mixture.

[0060] In one embodiment, in step (1), the material containing the long-chain dibasic acid and the organic mixed solvent can be fully mixed by pump circulation to obtain a first mixture.

[0061] In one embodiment, the mass ratio of the material containing the long-chain dibasic acid to the organic mixed solvent can be 1:(1-50), further 1:(2-30), for example 1:3.5, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, etc.

[0062] Furthermore, in step (1), after the heating, the mixture is kept warm and stirred until extraction equilibrium is reached.

[0063] The "extraction equilibrium" means that the content (wt%) of the long-chain dibasic acid in the extraction phase is stable. In other words, even if the heat preservation and stirring treatment time is extended, the content of the long-chain dibasic acid in the extraction phase obtained after standing and stratification does not increase, and the extraction equilibrium state is reached.

[0064] In one embodiment, the time of the heat preservation and stirring treatment in step (1) is 0.25 to 12 hours, further 0.5 to 12 hours, preferably 1 to 9 hours, preferably 1 to 6 hours, for example 65 minutes, 100 minutes, 120 minutes, 150 minutes, 240 minutes, 300 minutes, etc.

[0065] In step (1) of one embodiment, the heat-insulating stirring treatment is followed by a static treatment to obtain a stable extract phase, which is then separated.

[0066] The standing time may be sufficient to form a stable extraction phase and a raffinate phase.

[0067] In step (1) of one embodiment, the extract phase is separated after the separation is performed while the solid content in the extract phase no longer changes.

[0068] In one embodiment, the extract phase layer (second mixture) containing most of the target product and the raffinate phase layer containing most of the impurities can be separated by static separation, centrifugal separation, or other operation methods.

[0069] In one embodiment, the second mixture is in a clear state.

[0070] In one embodiment, the turbidity of the second mixture is 6 or less, further 4 or less, further 3 or less.

[0071] In one embodiment, the method may further include filtering the insoluble matter in the second mixture to remove the insoluble matter, and then recovering the long-chain dibasic acid in the second mixture.

[0072] In one embodiment, the method for recovering the long-chain dibasic acid from the second mixture comprises:

[0073] The second mixture is cooled, solid is precipitated, solid-liquid is separated, washed, and dried to obtain a long-chain dibasic acid (first long-chain dibasic acid product). The terminal temperature of the second mixture cooling is less than or equal to 50°C, further 5-50°C, further 10-30°C.

[0074] In one embodiment, the cooling process of the second mixture includes:

[0075] a. cooling the second mixture system to a turbidity of 6 to 15 NTU and then incubating for 0.25 h or more, further 0.25 to 5 h, further 0.25 to 3 h, further 0.25 to 2 h; and

[0076] b. Cooling the second mixture system to the endpoint temperature. The cooling rate to the endpoint temperature can be 0.5 to 20°C / h, further 0.5 to 10°C / h, for example 1°C / h, 6°C / h, 15°C / h, 18°C / h.

[0077] Generally, after the second mixture is cooled to the end temperature, the turbidity of the system reaches more than 100 NTU.

[0078] In one embodiment, the method for recovering the long-chain dibasic acid from the second mixture includes: directly evaporating the second mixture to remove the solvent to obtain the long-chain dibasic acid. In addition, the evaporated solvent or the mother solvent solution after crystallization can be recycled.

[0079] In one embodiment, the extraction and purification process of the long-chain dibasic acid further comprises step (3), wherein step (3) comprises: subjecting the first long-chain dibasic acid product obtained in step (2) to a refining treatment. The refining treatment comprises any one or a combination of two of the following methods:

[0080] Method (I) can be refined by solvent crystallization: the first long-chain dibasic acid product is dissolved in a solvent and then crystallized. Further, after the first long-chain dibasic acid product is dissolved in a solvent, it can be decolorized and filtered by activated carbon, then cooled and crystallized, filtered, washed, and dried to obtain a long-chain dibasic acid product.

[0081] Method (ii) uses vacuum distillation for refining. The number of distillation stages depends on the required purity of the product, and multi-stage distillation can be used to improve the purity of the product. The vacuum distillation includes high vacuum distillation or molecular distillation.

[0082] When the purification treatment is carried out by combining the method (I) and the method (II), there is no particular limitation on the order of using the method (I) and the method (II). For example, the purification is carried out by combining crystallization and high vacuum distillation or molecular distillation: crystallization can be performed first and then distillation, or distillation can be performed and then crystallization.

[0083] Furthermore, in method (a), the terminal temperature of the cooling crystallization is 20 to 45°C, and further 20 to 35°C.

[0084] Furthermore, in method (I), the solvent includes one or more of alcohol compounds, organic acid compounds, ester compounds, ketone compounds, and alkane compounds. The organic acid compounds may be organic monobasic acids with 1 to 4 carbon atoms, such as formic acid and acetic acid; the alcohol compounds may be monohydric alcohols or dihydric alcohols with 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol, and n-butanol; the ester compounds include ethyl acetate and butyl acetate. The ketones include acetone and butanone; the alkane compounds include straight-chain or branched alkanes and cycloalkanes with 5 to 23 carbon atoms. The concentration of the above substances in the solvent is above 90 wt%, for example, the solvent is a mixture of acetic acid and water with an acetic acid content of above 90 wt%.

[0085] Furthermore, in the method (I), the mass ratio of the long-chain dibasic acid to the solvent is 1:1 to 15, further 1:1 to 10. The dissolution process may be heated to promote dissolution, and the heating temperature is 50 to 120°C, further 60 to 100°C.

[0086] Further, in method (a), the amount of activated carbon used in the activated carbon decolorization process is 0.1wt% to 5wt% of the system mass, further 0.5wt% to 4wt%, further 1wt% to 4wt%. The temperature of the activated carbon decolorization treatment is 50 to 120°C, further 60 to 100°C.

[0087] Further, in the method (ii), the pressure of the main evaporator of the molecular distillation can be 0.1-30Pa, and can further be 0.1-20Pa, such as 1Pa, 2Pa, 5Pa, 6Pa, 8Pa, 10Pa, 12Pa, 16Pa, 18Pa, 20Pa, 25Pa. The evaporation surface temperature of the main evaporator of the molecular distillation is 130-250°C, and can further be 130-230°C, such as 140°C, 150°C, 160°C, 180°C, 200°C, 210°C, 220°C, 240°C. The condensation surface temperature of the main evaporator of the molecular distillation is 110-160°C, and can further be 110-150°C, such as 120°C, 135°C, 140°C, 145°C, 150°C, 155°C. The feed inlet temperature of the molecular distillation is 115-160°C, and can further be 120-150°C, for example, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C.

[0088] Further, in the method (ii), the theoretical plate number of the distillation tower used in the high vacuum distillation can be 8 to 24, and can further be 9 to 18, for example, 10, 12, 18, 24. Preferably, a packed tower is used, and the packing can be a commonly used packing in the art, such as a corrugated wire mesh packing. The top pressure of the distillation tower used in the high vacuum distillation can be 1 to 100 Pa, and can further be 25 to 80 Pa, for example, 20 Pa, 30 Pa, 60 Pa, 70 Pa, 80 Pa. The top temperature of the distillation tower used in the high vacuum distillation can be 160 to 250 ° C, and can further be 180 to 250 ° C, for example, 170 ° C, 185 ° C, 190 ° C, 195 ° C, 200 ° C, 210 ° C, 220 ° C, 225 ° C, 228 ° C, 230 ° C, 232 ° C, 235 ° C, 238 ° C, 240 ° C, 245 ° C. The bottom temperature of the distillation tower used in the high vacuum distillation can be 180-270° C., further 200-270° C., for example 190° C., 200° C., 210° C., 220° C., 230° C., 240° C., 243° C., 245° C., 248° C., 250° C., 255° C., 260° C., 265° C. The reflux ratio of the high vacuum distillation can be (1-10):1, further (2-8):1, for example 1:1, 2:1, 5:1, 6:1, 8:1, 10:1.

[0089] In one embodiment, multiple mixed solvent extractions (ie, multi-stage extractions) may be used to increase the yield of long-chain dibasic acids.

[0090] An embodiment of the present invention further provides a long-chain dibasic acid product, wherein the long-chain dibasic acid content is ≥80wt%, the light transmittance is ≥70%, the monobasic acid content is ≤1wt%, and the solvent residue is <800ppm.

[0091] The extraction process of one embodiment of the present invention can effectively remove impurities such as bacteria, pigments, proteins, etc. by a simple separation method; it avoids the disadvantages of large investment and high operating costs caused by the traditional extraction and separation methods that require a large amount of ceramic membrane ultrafiltration, or activated carbon decolorization, filtration to remove bacteria and pigment substances.

[0092] In the extraction process of one embodiment of the present invention, the organic mixed solvent can be recycled.

[0093] The extraction process of one embodiment of the present invention can obtain a long-chain dibasic acid product with high purity, and can be widely used in hot melt adhesives, rust inhibitors, fragrances, coatings, lubricating oils, and nylon polymerization raw materials.

[0094] The extraction process of one embodiment of the present invention can separate effective long-chain dibasic acid components from complex components, which is beneficial for further purification.

[0095] The extraction process of one embodiment of the present invention can recycle the solvent used, without generating waste salt and less waste water; and has good separation effect on impurities such as pigments and inorganic salts.

[0096] The following is a further description of the extraction process of long-chain dibasic acid according to one embodiment of the present invention in conjunction with a specific example. The analysis and detection methods involved are as follows:

[0097] 1. Gas chromatography detection of dibasic acid:

[0098] Standard dibasic acid samples were used as controls, with reference to GB5413.27-2010 Determination of fatty acids in infant foods and dairy products.

[0099] 2. Transmittance measurement:

[0100] The product was mixed with a sodium hydroxide solution to obtain a long-chain dibasic acid sodium salt aqueous solution with a mass concentration of 5%, and then the transmittance at 440 nm was detected by UV.

[0101] 3. Turbidity test of the second mixture (extract phase): The extract phase is clear before cooling, and crystals precipitate during the cooling process, causing the turbidity of the system to increase. Turbidity (unit: NTU) test method: Use the nephelometric method, and refer to the US EPA 180.1.

[0102] 4. The yield of long-chain dibasic acid is calculated as follows: Yield of long-chain dibasic acid (%) = (mass of long-chain dibasic acid product (kg) × content of long-chain dibasic acid (%)) / (mass of bottom material (kg) × mass content of long-chain dibasic acid in bottom material (%)) × 100%.

[0103] Preparatory Example 1

[0104] Referring to the fermentation method of Example 4 of patent document CN1570124A, a dodecanedioic acid fermentation broth was obtained. The dodecanedioic acid fermentation broth was first sterilized by membrane filtration to obtain a filtrate, and then 3wt% of activated carbon by mass of dodecanedioic acid in the filtrate was added to decolorize at 60°C. The decolorized filtrate was acidified and precipitated, filtered, and dried to obtain a crude dodecanedioic acid product (purity 98.2wt%).

[0105] The crude dodecanedioic acid was refined according to Example 30 of CN1570124A. The mother solvent solution after filtering the crystals in the refining process was passed through a distillation tower to recover the solvent, and the remainder was the bottom material (wherein the total content of 9-18 carbon dibasic acids was 76.5wt%).

[0106] Preparatory Example 2

[0107] Referring to the fermentation method of Example 5 of patent document CN1570124A, tridecanedioic acid fermentation broth was obtained. The tridecanedioic acid fermentation broth was acidified to pH 2.7 by adding sulfuric acid, and filtered to obtain a crude tridecanedioic acid product (purity 85 wt%).

[0108] Solvent refining was adopted with reference to Example 30 of CN1570124A. After filtering the crystals in the solvent refining process, the mother solvent liquor was passed through a distillation tower to recover the solvent, and the remainder was the bottom material (the content of 9-18 carbon dibasic acid was 55.2 wt%).

[0109] Example 1

[0110] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0111] (1) A mixed solvent prepared in a mass ratio of 20% acetic acid and 80% kerosene was added to the bottom material in a ratio of 1:4, and the mixture was heated to 90° C., stirred for 75 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.81 NTU).

[0112] (2) The second mixture is cooled to 26° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0113] The process of cooling the second mixture to 26°C is as follows: first, the second mixture is cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the mixture is cooled to 26°C at a rate of 5°C / h.

[0114] According to calculation, the yield of long-chain dibasic acid in the bottom material after treatment in steps (1) to (2) is 53%.

[0115] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0116] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0117] The raffinate phase of step (2) is further subjected to multi-stage extraction, and the total extraction yield reaches more than 95%.

[0118] Example 2

[0119] The raw material used was the tower bottom material prepared according to the method of Preparatory Example 1.

[0120] (1) A mixed solvent prepared in a mass ratio of 20% ethyl acetate and 80% kerosene was added to the bottom material in a ratio of 1:4, and the mixture was heated to 90° C., stirred for 65 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 1.0 NTU).

[0121] (2) The second mixture is cooled to 30° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0122] The process of cooling the second mixture to 30° C. is as follows:

[0123] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 30° C. at a rate of 5° C. / h.

[0124] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 4 times the weight thereof, and heated to 95°C for dissolution. 1.8wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0125] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0126] Example 3

[0127] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0128] (1) A mixed solvent prepared in a mass ratio of 20% butanol and 80% n-tridecane was added to the bottom material in a ratio of 1:6 between the mass of the bottom material and the solvent, and the mixture was heated to 90° C., stirred for 100 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 1.1 NTU).

[0129] (2) The second mixture is cooled to 30° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0130] The process of cooling the second mixture to 30° C. is as follows:

[0131] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 40° C. at a rate of 5° C. / h.

[0132] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0133] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0134] Example 4

[0135] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0136] (1) Adding a mixed solvent prepared in a mass ratio of 20% acetic acid and 80% kerosene to the bottom material in a ratio of 1:6, heating to 90° C., stirring at this temperature for 100 minutes, and then allowing the layers to stand, and then separating the extract phase to obtain a second mixture (turbidity of 0.82 NTU).

[0137] (2) The second mixture is cooled to 30° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0138] The process of cooling the second mixture to 30° C. is as follows:

[0139] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.8 h; then, the temperature was cooled to 30° C. at a rate of 7° C. / h.

[0140] (3) The first long-chain dibasic acid product is subjected to molecular distillation. The pressure of the main evaporator of the molecular distillation device is 18 Pa, the evaporation surface temperature of the main evaporator is 160° C., the condensation surface temperature of the main evaporator is 128° C., and the feed inlet temperature is 130° C. The fractions are collected to obtain a long-chain dibasic acid product.

[0141] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0142] Example 5

[0143] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0144] (1) Adding a mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-dodecane to the bottom material in a ratio of 1:10, heating to 90° C., stirring at this temperature for 100 minutes, and then allowing the layers to stand, and then separating the extract phase to obtain a second mixture (turbidity of 0.15 NTU).

[0145] (2) The second mixture is cooled to 30° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0146] The process of cooling the second mixture to 30° C. is as follows:

[0147] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 30° C. at a rate of 5° C. / h.

[0148] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0149] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0150] Example 6

[0151] The raw material used was the tower bottom material prepared according to the method of Preparatory Example 2.

[0152] (1) A mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-dodecane was added to the bottom material in a ratio of 1:10 between the mass of the bottom material and the mass of the solvent, and the mixture was heated to 90° C., stirred for 100 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.14 NTU).

[0153] (2) The second mixture is cooled to 30° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0154] The process of cooling the second mixture to 30° C. is as follows:

[0155] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 30° C. at a rate of 8° C. / h.

[0156] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0157] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0158] Example 7

[0159] The raw material used was the tower bottom material prepared according to the method of Preparatory Example 2.

[0160] (1) A mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-dodecane was added to the bottom material at a ratio of 1:8, and the mixture was heated to 65° C., stirred for 120 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.16 NTU).

[0161] (2) The second mixture is cooled to 32° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0162] The process of cooling the second mixture to 32° C. is as follows:

[0163] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 32° C. at a rate of 5° C. / h.

[0164] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0165] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0166] Example 8

[0167] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0168] (1) Adding a mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-dodecane to the bottom material in a ratio of 1:10, heating to 90° C., stirring at this temperature for 100 minutes, and then allowing the layers to stand, and then separating the extract phase to obtain a second mixture (turbidity of 0.15 NTU).

[0169] (2) directly cooling the second mixture to 35° C. at a rate of 12° C. / h, filtering, washing, and drying at 95° C. to obtain a first long-chain dibasic acid product.

[0170] (3) The first long-chain dibasic acid product is subjected to high vacuum distillation, the distillation tower has 12 plates, the top pressure is 60 Pa, the top temperature is 238° C., the bottom temperature is 250° C., the reflux ratio is 5:1, and the fractions are collected and cooled to obtain a long-chain dibasic acid product.

[0171] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0172] Example 9

[0173] The raw material used was crude dodecanedioic acid prepared according to the method of Preparative Example 1.

[0174] (1) A mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-pentane was added to the crude dodecanedioic acid in a ratio of 1:3, and the mixture was heated to 90° C., stirred for 100 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.25 NTU).

[0175] (2) The second mixture is cooled to 35° C., filtered, washed, and dried at 95° C. to obtain the first dodecanedioic acid product.

[0176] The process of cooling the second mixture to 35° C. is as follows:

[0177] First, the second mixture was cooled to a system turbidity of 10.0 NTU and then kept warm for 0.5 h; then, the temperature was cooled to 35° C. at a rate of 15° C. / h.

[0178] (3) The first dodecanedioic acid product is subjected to high vacuum distillation, the distillation tower has 12 plates, the top pressure is 60 Pa, the top temperature is 238° C., the bottom temperature is 250° C., the reflux ratio is 5:1, the fractions are collected, and the distillates are cooled to obtain the dodecanedioic acid product.

[0179] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0180] Example 10

[0181] The raw material used was crude dodecanedioic acid prepared according to the method of Preparative Example 1.

[0182] (1) A mixed solvent prepared in a mass ratio of 10% acetic acid, 10% butanol, and 80% decane was added to the crude dodecanedioic acid in a ratio of 1:6, and the mixture was heated to 90° C., stirred for 100 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.37 NTU).

[0183] (2) The second mixture is cooled to 30° C., filtered, and dried at 95° C. to obtain the first dodecanedioic acid product.

[0184] The process of cooling the second mixture to 30° C. is as follows:

[0185] First, the second mixture was cooled to a system turbidity of 8.0 NTU and then kept warm for 1.5 h; then, the temperature was cooled to 30° C. at a rate of 15° C. / h.

[0186] (3) The dodecanedioic acid is subjected to high vacuum distillation, the distillation tower has 12 plates, the top pressure is 60 Pa, the top temperature is 238° C., the bottom temperature is 250° C., the reflux ratio is 5:1, the fractions are collected, and the fractions are cooled to obtain the dodecanedioic acid product.

[0187] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0188] Embodiment 11

[0189] The raw material used was crude dodecanedioic acid prepared according to the method of Preparative Example 1.

[0190] (1) A mixed solvent prepared in a mass ratio of 3% acetic acid and 97% kerosene was added to the crude dodecanedioic acid in a ratio of 1:20, and the mixture was heated to 90° C., stirred for 100 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.18 NTU).

[0191] (2) The second mixture is cooled to 35° C., filtered, washed, and dried at 95° C. to obtain the first dodecanedioic acid product.

[0192] The cooling process of cooling the second mixture extract phase to 35° C. is as follows:

[0193] First, the second mixture was cooled to a system turbidity of 7.5 NTU and then kept warm for 2 hours; then, the temperature was cooled to 35° C. at a rate of 15° C. / h.

[0194] (3) Add dodecanedioic acid to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heat to dissolve at 95°C. Add 2.5wt% activated carbon to the solution, decolorize at 95°C for 30 minutes, and filter. Cool the filtrate to 30°C for crystallization, and then perform solid-liquid separation. Wash the solid with water and dry to obtain the dodecanedioic acid product.

[0195] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0196] Example 12

[0197] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0198] (1) A mixed solvent prepared in a mass ratio of 10% butyric acid and 90% n-pentane was added to the bottom material in a ratio of 1:4, and the mixture was heated to 80° C., stirred for 75 minutes, and then allowed to stand and separate, and then the extract phase was separated to obtain a second mixture (turbidity of 0.24 NTU).

[0199] (2) The second mixture is cooled to 26° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0200] The process of cooling the second mixture to 26°C is as follows: first, the second mixture is cooled to a system turbidity of 11 NTU and then kept warm for 0.5 h; then, the temperature is cooled to 26°C at a rate of 7°C / h.

[0201] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95° C. for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95° C. for 35 min and then filtered. The obtained filtrate is cooled to 28° C. for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0202] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0203] Comparative Example 1

[0204] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0205] (1) Kerosene was added to the bottom material in a ratio of 1:4, and the mixture was heated to 90° C. After being stirred for 75 minutes, the mixture was allowed to stand and separate into layers. The extract phase was then separated to obtain a second mixture (with a turbidity of 0.52 NTU).

[0206] (2) The second mixture is cooled to 26° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0207] The process of cooling the second mixture to 26°C is as follows: first, the second mixture is cooled to a system turbidity of 8.0 and then kept warm for 0.5 h; then, the temperature is cooled to 26°C at a rate of 5°C / h.

[0208] According to calculation, the yield of long-chain dibasic acid in the bottom material after treatment in steps (1) to (2) is 1.4%.

[0209] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0210] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0211] Comparative Example 2

[0212] The raw material used was the tower bottom material prepared according to the method of Preparation Example 1.

[0213] (1) Add acetic acid to the bottom material in a ratio of 1:4 between the mass of the bottom material and the mass of acetic acid, heat to 90° C., keep warm and stir for 75 minutes, and then stand for 75 minutes without obvious stratification. Remove insoluble matter by filtration to obtain a second mixture (dark brown, turbidity>50 NTU).

[0214] (2) The second mixture is cooled to 26° C., filtered, washed, and dried at 95° C. to obtain a first long-chain dibasic acid product.

[0215] The process of cooling the second mixture to 26°C is as follows: first, the second mixture is cooled to a system turbidity of 8.0 and then kept warm for 0.5 h, and then cooled to 15°C at a rate of 5°C / h.

[0216] According to calculation, the yield of long-chain dibasic acid in the bottom material after treatment in steps (1) to (2) is 16%.

[0217] (3) The first long-chain dibasic acid product is added to a mixture of 95wt% (acetic acid content) acetic acid and water in an amount of 3 times the weight thereof, and heated to 95°C for dissolution. 2.5wt% activated carbon is added to the solution, and the mixture is decolorized at 95°C for 30 minutes and then filtered. The obtained filtrate is cooled to 30°C for crystallization, and then solid-liquid separation is performed. The obtained solid is washed with water and then dried to obtain the long-chain dibasic acid product.

[0218] The obtained product was tested for purity, transmittance, impurity content, etc., and the relevant results are shown in Table 1.

[0219] Preparation of hot melt adhesive

[0220] The long-chain dibasic acid products obtained in the examples and comparative examples are used to prepare hot melt adhesives, and the preparation process is as follows:

[0221] (1) Under a nitrogen atmosphere, 260 g of pentamethylenediamine, 200 g of adipic acid, 322 g of a long-chain dibasic acid product, 65 g of isophthalic acid, 250 g of caprolactam and water were uniformly mixed to prepare an 80 wt % salt solution. The pH value of the salt solution was 7.89 when the concentration was 10 wt %.

[0222] (2) The salt solution obtained in step (1) was filtered and heated, the pressure in the reaction system was raised to 1.7 MPa, the air was exhausted, and the pressure was maintained. At the end of the pressure maintenance, the temperature of the reaction system was 244°C, and the pressure was reduced to 0.01 MPa (gauge pressure) and maintained for 20 min. After the pressure reduction, the temperature of the reaction system was 264°C, and the pressure was maintained at -0.09 MPa. The vacuum time was maintained for 22 min. The temperature after vacuum was 269°C, and a polyamide hot melt adhesive melt was obtained.

[0223] (3) Melting and discharging the material, and pelletizing it underwater; the temperature of the cooling water is 20° C., and the cooling time is 35 min to obtain polyamide hot melt adhesive resin chips.

[0224] The hot melt resin slices were subjected to peel strength test and yellow index test. The test method of peel strength was as follows: refer to the peel strength test standard FZ / T 80007.1-2006 for adhesive lining; the test of yellow index (YI value) was as follows: refer to ASTMD6290. The specific test results are shown in Table 1.

[0225] Table 1

[0226]

[0227] As shown in Table 1, the mixed solvent used in the present invention has a good extraction effect on long-chain dibasic acid, and the extraction efficiency is high. At the same time, the extraction system can prevent impurities such as pigments, bacterial proteins, etc. from entering the extraction phase, avoiding the traditional extraction and separation methods that require a large amount of ceramic membrane ultrafiltration, or activated carbon decolorization, filtration to remove bacteria and pigment substances, etc., which brings about large investment and high operating costs. Long-chain dibasic acid products have a wide range of applications, and the prepared hot melt adhesive products have good performance.

[0228] Unless otherwise defined, the terms used in the present invention have the meanings commonly understood by those skilled in the art.

[0229] The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various other substitutions, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but is only limited by the claims.

Claims

1. A process for extracting a long-chain dibasic acid, comprising the following steps: (1) extracting a material containing a long-chain dibasic acid; the extraction process comprising: Mixing the material containing the long-chain dibasic acid with an organic mixed solvent to obtain a first mixture; as well as The first mixture is subjected to a heat preservation and stirring treatment at 50 to 120° C., and then allowed to stand for stratification, and the extract phase is separated to obtain a second mixture; (2) recovering the long-chain dibasic acid from the second mixture; Wherein, the organic mixed solvent comprises a first solvent and a second solvent, the first solvent is selected from hydrocarbon compounds, petroleum products or a combination thereof, and the second solvent is selected from one, two or more of ester compounds, organic acid compounds and alcohol compounds; The mass ratio of the material containing the long-chain dibasic acid to the organic mixed solvent is 1:(1-50).

2. The extraction process according to claim 1, wherein: The ester compounds include phosphorus-oxygen ester compounds, fatty acid ester compounds with 1 to 10 carbon atoms, and further include one or a combination of two or more of di(2-ethylhexyl) phosphate, ethyl acetate, butyl acetate, and methyl acetate; And / or, the organic acid compound includes one or a combination of two or more fatty acids having 1 to 5 carbon atoms; And / or, the alcohol compound includes monohydric alcohol and / or polyhydric alcohol having 1 to 5 carbon atoms, and further includes any one of methanol, ethanol, propanol, butanol, isopropanol, and ethylene glycol, or a combination of two or more thereof; And / or, the hydrocarbon compound includes one, two or more of linear or branched alkanes, cycloalkanes and aromatic hydrocarbons with carbon atoms of 5 to 23; further includes one, two or more of pentane, hexane, heptane, octane, decane, n-undecane, n-tridecane, n-dodecane, n-hexadecane, benzene, toluene and ethylbenzene; And / or, the petroleum product includes gasoline and / or kerosene.

3. The extraction process according to claim 1, wherein the mass ratio of the material containing the long-chain dibasic acid to the organic mixed solvent is 1:(2-30); And / or, the water content of the material containing the long-chain dibasic acid is ≤50wt%, further ≤20wt%, further ≤10wt%; And / or, the content of the long-chain dibasic acid in the material containing the long-chain dibasic acid is 10 to 99 wt %; And / or, the insulation temperature of step (1) is 70-100° C.; And / or, the time of the heat preservation and stirring treatment in step (1) is 0.25 to 12 hours, further 0.5 to 12 hours.

4. The extraction process according to claim 1, wherein the organic mixed solvent contains more than 80 wt% of the first solvent; Furthermore, the organic mixed solvent comprises 80 to 97 wt % of the first solvent and 3 to 20 wt % of the second solvent.

5. The extraction process according to claim 1, wherein: The step (2) further comprises filtering the second mixture to remove insoluble matter therein, and then recovering the long-chain dibasic acid in the obtained filtrate.

6. The extraction process according to claim 1 or 5, wherein: The step (2) comprises: cooling the second mixture to precipitate solids, solid-liquid separation, washing, and drying to obtain a long-chain dibasic acid, wherein the terminal temperature of the cooling is less than or equal to 50° C.; Alternatively, the second mixture is subjected to evaporation treatment to remove the solvent to obtain the long-chain dibasic acid.

7. The extraction process according to claim 6, wherein: The cooling process of the second mixture comprises: a. Cooling the second mixture to a turbidity of 6 to 15 NTU and then keeping warm for more than 0.25 h; b. Continue cooling the second mixture to the end temperature.

8. The extraction process according to claim 7, wherein in step a, the holding time is 0.25 to 5 h, further 0.25 to 3 h, further 0.25 to 2 h; And / or, in step b, the cooling rate is 0.5 to 20°C / h, further 0.5 to 10°C / h.

9. The extraction process according to claim 6 or 7, wherein the turbidity of the system reaches above 100 NTU after the second mixture is cooled to the end temperature. 10 . The extraction process according to claim 1 , 6 or 7 , wherein the turbidity of the second mixture is 6 or less, further 4 or less, further 3 or less.

11. The extraction process according to claim 1, further comprising step (3): subjecting the first long-chain dibasic acid product obtained in step (2) to a refining treatment, wherein the refining treatment comprises any one of the following methods or a combination of two methods: Method (I): dissolving the first long-chain dibasic acid product in a solvent and then crystallizing; Method (two): the first long-chain dibasic acid product is refined by vacuum distillation.

12. The extraction process according to claim 11, in method (1), the first long-chain dibasic acid product is dissolved in a solvent, decolorized and filtered using activated carbon, then cooled and crystallized, filtered, washed, and dried to obtain a long-chain dibasic acid product.

13. The extraction process according to claim 11 or 12, wherein in method (1), the solvent comprises one or more of alcohol compounds, organic acid compounds, ester compounds, ketone compounds, and alkane compounds; And / or, the mass ratio of the long-chain dibasic acid to the solvent is 1:1-15, further 1:1-10.

14. The extraction process according to claim 13, wherein the organic acid compound is an organic monobasic acid having 1 to 4 carbon atoms, such as formic acid or acetic acid; and / or, the alcohol compound is a monohydric alcohol or a dihydric alcohol having 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol and n-butanol; And / or, the ester compound includes ethyl acetate and butyl acetate; And / or, the ketones include acetone and butanone; And / or, the alkane compounds include straight-chain or branched alkanes and cycloalkanes having 5 to 23 carbon atoms.

15. The extraction process according to claim 12, During the dissolution process with the solvent, heating is performed to promote dissolution, and the heating temperature is 50 to 120° C., and further 60 to 100° C.; And / or, the amount of activated carbon used in the activated carbon decolorization process is 0.1wt% to 5wt% of the system mass; and / or, the temperature of the activated carbon decolorization treatment is 50 to 120° C.; And / or, the terminal temperature of the temperature drop crystallization is 20-45°C.

16. The extraction process according to claim 11, in method (ii), the reduced pressure distillation includes high vacuum distillation or molecular distillation.

17. The extraction process according to claim 16, wherein the pressure of the main evaporator of the molecular distillation is 0.1-30 Pa; and / or, the evaporation surface temperature of the main evaporator of molecular distillation is 130-250°C; and / or, the condensing surface temperature of the main evaporator of molecular distillation is 110-160°C; And / or, the feed inlet temperature of the molecular distillation is 115-160°C.

18. The extraction process according to claim 16, wherein the distillation tower used in the high vacuum distillation has a theoretical plate number of 8 to 24; And / or, the top pressure of the distillation tower is 1 to 100 Pa; and / or, the top temperature of the distillation tower is 160-250° C.; and / or, the bottom temperature of the distillation tower is 180-270° C.; And / or, the reflux ratio is (1-10):

1.

19. The extraction process according to claim 1, wherein: The material containing the long-chain dibasic acid includes one or more of a crude long-chain dibasic acid, a residue after solvent recovery from a recrystallization mother liquor of a crude long-chain dibasic acid, a precipitate rich in long-chain dibasic acid recovered from a sewage treatment plant, and a slurry of other long-chain dibasic acids; And / or, the long-chain dibasic acid includes any one or more combinations of azelaic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedicarboxylic acid or 9-ene-octadecanedicarboxylic acid.

20. The extraction process according to claim 1, wherein: The organic mixed solvent comprises a first solvent and a second solvent, wherein the first solvent is selected from hydrocarbon compounds, petroleum products or a combination thereof, and the second solvent is selected from organic acid compounds; The hydrocarbon compound includes one, two or more of linear or branched alkanes, cycloalkanes and aromatic hydrocarbons with carbon atoms of 5 to 23; further includes one, two or more of pentane, hexane, heptane, octane, decane, n-undecane, n-tridecane, n-dodecane, n-hexadecane, benzene, toluene and ethylbenzene; The petroleum products include gasoline and / or kerosene; The organic acid compound includes one or a combination of two or more fatty acids having 1 to 5 carbon atoms.

21. According to the extraction process of claim 2 or 20, the organic acid compound includes one or a combination of two or more of fatty acids with 1 to 4 carbon atoms, and further, the fatty acid includes fatty monoacids and / or fatty diacids, and further includes any one or a combination of two or more of formic acid, acetic acid, propionic acid, and butyric acid.

22. A long-chain dibasic acid product, wherein: The content of the long-chain dibasic acid is ≥80wt%, and / or the light transmittance of the long-chain dibasic acid product is ≥70%, and / or the solvent residue of the long-chain dibasic acid product is <800ppm.

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