Bio-based succinic acid composition as well as preparation method and application thereof

Abstract

The invention provides a bio-based succinic acid composition as well as a preparation method and application thereof. The bio-based succinic acid composition comprises bio-based succinic acid and a readily oxidizable substance, the content of readily oxidizable substances in the bio-based succinic acid composition is less than or equal to 0.32 mL / g. The bio-based succinic acid composition is long in shelf life, small in b value change after aging and good in aging stability; and the polyester prepared from the bio-based succinic acid composition is lower in acid value, whiter in color and higher in molecular weight.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester preparation, and specifically relates to a bio-based succinic acid composition and a preparation method and application thereof. Background Art

[0002] Succinic acid is an important C4 compound. As an organic synthesis raw material, intermediate product or special chemical, it is widely used in food, light industry and pharmaceutical industry. It is the raw material for preparing basic chemical products such as 1,4-butanediol, tetrahydrofuran, γ-butyrolactone, N-methylpyrrolidone, and is also the main raw material for the fully biodegradable plastic polybutylene succinate (PBS). At present, the raw materials of succinic acid are mostly derived from petroleum resources (such as maleic anhydride as raw material) and are produced by chemical methods. However, petroleum resources are non-renewable and will produce a lot of pollution during the production process. Therefore, in order to avoid the depletion of fossil fuel resources and slow down the increase of carbon dioxide, and avoid environmental problems such as greenhouse effect caused by the increase of carbon dioxide, the preparation of bio-based succinic acid from biomass resources has become a feasible strategy. In addition, the method of preparing succinic acid from biomass resources can utilize renewable biomass resources, has the advantages of high efficiency, no dependence on petroleum, and low pollution, and can absorb fixed greenhouse gases (CO2 gas) during the biosynthesis process, which has become a hot spot for research and application at home and abroad in recent years.

[0003] Bio-based succinic acid is usually produced from biomass resources by fermentation and / or chemical conversion; therefore, bio-based succinic acid usually contains a variety of impurities, such as cell debris, proteins, amino acids directly from the fermentation broth, and nitrogen or ammonia and metal cations from fermentation bacteria. The presence of impurities will reduce the quality of succinic acid.

[0004] In addition, these impurities, especially oxidizable substances, have an adverse effect on the polyester prepared from succinic acid from biomass resources; for example, if oxidizable substances are present in large quantities, solid byproducts that are deposited in the reactor are easily produced during the polyester synthesis process, and the productivity of the polyester is limited, and high molecular weight polyester cannot be obtained, or in order to obtain high molecular weight polyester, a longer residence time is often required, resulting in a high acid value of the polyester and poor hydrolysis resistance. In addition, in the case of intermittent polymerization processes, due to the presence of impurities such as oxidizable substances, substantial changes in process conditions are required to adjust the final viscosity of the desired polyester, but such adjustments often also result in a high acid value of the obtained polyester (acid value ≥ 2.0 mg KOH / g) and a decrease in the hydrolysis resistance of the polyester.

[0005] Therefore, it is an urgent problem to be solved in the art to develop a bio-based succinic acid composition that has both a long shelf life and excellent aging resistance stability, while being able to reduce the acid value and color value of polyester and being conducive to the preparation of high molecular weight polyester. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a bio-based succinic acid composition and a preparation method thereof. The bio-based succinic acid composition has a long shelf life, good aging stability, and a small change in b value after aging; and the polyester prepared from the bio-based succinic acid composition has a low acid value, a whiter color and a higher molecular weight.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a bio-based succinic acid composition, wherein the bio-based succinic acid composition comprises bio-based succinic acid and an oxidizable substance; the content of the oxidizable substance in the bio-based succinic acid composition is ≤0.32 mL / g.

[0009] In the present invention, the presence of easily oxidized substances is beneficial to improving the shelf life of bio-based succinic acid, while controlling the content of easily oxidized substances in the bio-based succinic acid and the b value of the bio-based succinic acid within a specific range, thereby ensuring that the bio-based succinic acid has a long shelf life while taking into account the aging stability of the bio-based succinic acid, so that the b value of the bio-based succinic acid changes less after aging; and preparing polyester using the bio-based succinic acid as a raw material is beneficial to reducing the acid value of the polyester, increasing the intrinsic viscosity of the polyester, making the polyester less prone to yellowing, and is beneficial to improving the production efficiency of the polyester, and avoiding the generation of solid by-products.

[0010] In the present invention, the content of easily oxidized substances in the bio-based succinic acid composition is ≤0.32 mL / g, for example, it can be 0.001 mL / g, 0.005 mL / g, 0.01 mL / g, 0.02 mL / g, 0.04 mL / g, 0.06 mL / g, 0.08 mL / g, 0.1 mL / g, 0.12 mL / g, 0.14 mL / g, 0.16 mL / g, 0.18 mL / g, 0.2 mL / g, 0.22 mL / g, 0.24 mL / g, 0.26 mL / g, 0.28 mL / g, 0.30 mL / g or a range between any of the above values.

[0011] In the present invention, the content of the easily oxidizable substance is expressed by the volume of 0.1 mol / L potassium permanganate consumed by 1 g of the bio-based succinic acid composition, that is, the unit is mL / g.

[0012] Preferably, the content of easily oxidizable substances in the bio-based succinic acid composition is 0.01 to 0.29 mL / g, more preferably 0.12 to 0.24 mL / g.

[0013] In the present invention, it is more preferred that the easily oxidized substance content is within the above-defined range. If the easily oxidized substance content is too low, the shelf life of the bio-based succinic acid will be short; if the easily oxidized substance content is too high, the acid value of the obtained polyester will be high, which is not conducive to the preparation of high molecular weight polyester. GB / T34686-2017 stipulates that the easily oxidized substance content of qualified succinic acid products is ≤0.60 mL / g.

[0014] In the present invention, the oxidizable substances are oxidizable substances produced in the process of preparing succinic acid using biomass resources as raw materials.

[0015] Preferably, the oxidizable substances include: cell debris, proteins, amino acids, etc. directly derived from the fermentation broth, and also include reducing agents that are non-toxic or low-toxic to microorganisms, such as sulfites, thiosulfates, etc., which may be selectively added based on the need to adjust the redox potential of the fermentation system.

[0016] Preferably, according to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, the b value of the bio-based succinic acid composition is ≤4.2, for example, it can be 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2 or a range between any of the above values; preferably, the b value is ≤2.5; more preferably, the b value is 0.7 to 1.6.

[0017] Preferably, according to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, after aging for 2 hours at 150° C., the bio-based succinic acid composition has a Δb value ≤ 2.5, preferably a Δb value ≤ 2.0; more preferably a Δb value ≤ 1.5.

[0018] In the present invention, the Δb is the change in b value after aging, that is, the difference between the b value of the bio-based succinic acid composition after aging and the b value of the bio-based succinic acid composition before aging.

[0019] In a second aspect, the present invention provides a method for preparing the bio-based succinic acid composition according to the first aspect, the preparation method comprising the following steps:

[0020] (1) Using biomass resources as raw materials to prepare succinic acid stock solution;

[0021] (2) purifying the succinic acid stock solution obtained in step (1) to obtain the bio-based succinic acid composition;

[0022] The purification method comprises treating with an oxidant solution; the mass of the oxidant solution accounts for 18-50wt% of the mass of the solution to be treated with the oxidant solution, and the concentration of the oxidant solution is 0.02-0.07mol / L.

[0023] Alternatively, the preparation method comprises the following steps: (S) recrystallizing and filtering the bio-based succinic acid having an oxidizable substance content of ≥0.35 mL / g to obtain the bio-based succinic acid composition.

[0024] In the present invention, in the preparation method, bio-based succinic acid with a specific content of easily oxidized substances can be obtained by adding a specific content of an oxidant solution for treatment or by recrystallizing the bio-based succinic acid with a low content of easily oxidized substances.

[0025] In the present invention, the solution to be treated with the oxidant solution can be a succinic acid stock solution, or a solution of the succinic acid stock solution after other purification treatments (such as neutralization with a neutralizer, adsorption with an ion exchange resin, decolorization with activated carbon, etc.); the 18-50wt% refers to the total mass of the oxidant solution including the solvent.

[0026] In the present invention, the mass of the oxidant solution accounts for 18 to 50 wt% of the mass of the solution to be treated with the oxidant solution, for example, it can be 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38wt%, 39wt%, 40wt%, 42wt%, 44wt%, 45wt%, 46wt%, 48wt%, 50wt% or any range therebetween; the concentration of the oxidant solution is 0.02-0.07mol / L, for example, 0.02mol / L, 0.03mol / L, 0.04mol / L, 0.05mol / L, 0.06mol / L, 0.07mol / L or any range therebetween.

[0027] Preferably, the mass of the oxidant solution accounts for 20-40 wt %, more preferably 25-35 wt % of the mass of the solution to be treated with the oxidant solution.

[0028] In the present invention, the content of the oxidant solution is within the above range, which can ensure that the content of easily oxidized substances in the obtained bio-based succinic acid composition is low and avoid cost increase.

[0029] Preferably, the oxidant solution comprises at least one of an aqueous potassium permanganate solution, an aqueous hydrogen peroxide solution, and a chloric acid solution, more preferably an aqueous potassium permanganate solution and / or a chloric acid solution.

[0030] Preferably, the temperature for treatment with the oxidant solution is 60-90°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 85°C, 90°C or any range between the above values; the time is 35-165min, for example, it can be 35min, 40min, 45min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 165min or any range between the above values.

[0031] Preferably, the mass concentration of succinic acid in the succinic acid stock solution in step (1) is 70 to 95 g / L, for example, it can be 70 g / L, 72 g / L, 75 g / L, 78 g / L, 80 g / L, 82 g / L, 85 g / L, 88 g / L, 90 g / L, 92 g / L, 95 g / L or a range between any of the above values.

[0032] Preferably, the biomass resources include plant resources and / or animal resources, preferably plant resources.

[0033] In the present invention, the plant resources refer to biomass resources that can convert the sun's light energy into starch or cellulose and store it through photosynthesis; the animal resources refer to biomass resources that grow and develop by preying on plants; the plant resources or animal resources also include products obtained by processing plant resources or animal resources.

[0034] In the present invention, illustratively, the plant resources include but are not limited to wood, rice straw, rice husk, rice bran, old rice, corn, sugarcane, cassava, corn nodes, cassava starch residue, bagasse, vegetable oil residue, barley, soybeans, food waste, etc.

[0035] In the present invention, the preparation method also includes converting the biomass resources into a carbon source, and then preparing a succinic acid stock solution using the carbon source as a raw material; the method for converting into a carbon source includes but is not limited to chemical treatment, physical treatment, biological treatment, etc.; illustratively, the chemical treatment can be acid treatment (for example, treatment with strong acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc.), alkali treatment, ammonia freezing, cooking and blasting treatment, solvent extraction treatment, supercritical fluid treatment, oxidant treatment, etc.; the physical treatment can be pulverization treatment, cooking and blasting treatment, microwave treatment, electron beam irradiation treatment, etc.; the biological treatment can be microbial treatment, enzyme treatment, etc.

[0036] In the present invention, the carbon source illustratively includes but is not limited to hexoses such as glucose, mannose, galactose, fructose, sorbose, tagatose, etc.; pentoses such as arabinose, xylose, ribose, xylulose, ribulose, etc.; disaccharides or polysaccharides such as pentosans, sucrose, starch, cellulose, etc., preferably glucose, fructose, xylose, and particularly preferably glucose.

[0037] Preferably, the preparation method in step (1) comprises microbial fermentation and / or chemical conversion, preferably microbial fermentation.

[0038] In the present invention, the microorganisms used in the microbial fermentation method can produce dicarboxylic acids, and illustratively include: anaerobic bacteria, facultative anaerobic bacteria, aerobic bacteria, etc.; the anaerobic bacteria can be, for example, Anaerobiospirillum (US5143833A); the facultative anaerobic bacteria can be, for example, Actinobacillus (US5504004A), Escherichia (US5770435A), etc.; the aerobic bacteria can be, for example, Corynebacterium (Japanese Patent Publication No. 11-113588 or CN103183813A), and these documents are introduced here as reference.

[0039] In the present invention, step (1) uses biomass resources as raw materials to prepare the succinic acid stock solution by conventional methods in the art; illustratively, in the preparation method, step (1) uses biomass resources as raw materials to prepare the succinic acid stock solution by conventional methods in the art, for example, it can be prepared by referring to the method in CN118459331A.

[0040] Preferably, the purification method in step (2) further comprises any one of filtration, treatment with a neutralizing agent, treatment with activated carbon, and treatment with an ion exchange resin, or a combination of at least two thereof.

[0041] In the present invention, the neutralizing agent includes: ammonia, ammonium carbonate, urea, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, etc. Preferably, at least one of ammonia, ammonium carbonate or urea is used. The alkali metal hydroxide or alkaline earth metal hydroxide includes but is not limited to a mixture of one or more of NaOH, KOH, Ca(OH)2, Mg(OH)2; the alkali metal carbonate or alkaline earth metal carbonate includes but is not limited to a mixture of one or more of Na2CO3, K2CO3, CaCO3, MgCO3.

[0042] Preferably, the treatment time with the neutralizer is 60 to 120 min; the mass concentration of the neutralizer is 18 to 42 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt% or the range between any of the above values.

[0043] Preferably, the neutralizing agent treatment further includes filtering and washing steps.

[0044] Preferably, based on the volume of 1 L of the solution to be treated with activated carbon, the mass of the activated carbon is 5 to 8 g, for example, 5 g, 5.2 g, 5.5 g, 5.8 g, 6 g, 6.2 g, 6.5 g, 6.8 g, 7 g, 7.2 g, 7.5 g, 7.8 g, 8 g or a range between any of the above values.

[0045] In the present invention, the solution to be treated with activated carbon can be a succinic acid stock solution, or a solution that has undergone other purification treatments, such as filtration, neutralization with a neutralizing agent, and adsorption with an ion exchange resin.

[0046] Preferably, the ion exchange resin comprises a cation exchange resin and / or an anion exchange resin.

[0047] In the present invention, the treatment with a cation exchange resin comprises: passing the solution to be treated with the ion exchange resin through a column filled with the cation exchange resin, eluting with water, and collecting the effluent; the mass of the water is 2 to 5 times the mass of the solution to be treated with the ion exchange resin, for example, it can be 2 times, 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, 5 times or a range between any of the above values.

[0048] In the present invention, the treatment with anion exchange resin includes: passing the solution to be treated with ion exchange resin through a column filled with anion exchange resin, eluting with water, and collecting the effluent; the mass of the water is 2 to 5 times the mass of the solution to be treated with ion exchange resin, for example, it can be 2 times, 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, 5 times or any range between the above values.

[0049] Preferably, after the purification in step (2), the step of reduced pressure distillation and / or cooling crystallization is also included.

[0050] In the present invention, the temperature of the reduced pressure distillation is 65 to 75° C., and the pressure is -0.07 to -0.1 MPa. When the content of succinic acid is greater than 15wt%, the distillation is stopped; the concentrated succinic acid solution is placed at a low temperature (≤8° C.) for cooling and crystallization to obtain the bio-based succinic acid composition.

[0051] In the present invention, the bio-based succinic acid with an easily oxidizable substance content of ≥0.35 mL / g in step (S) can be commercially available or bio-based succinic acid prepared by conventional methods.

[0052] Preferably, the recrystallization method in step (S) comprises: mixing the bio-based succinic acid with a solvent at 60-100°C (for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C or any range between the above values), and then cooling the mixture to 15-25°C (for example, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 22°C, 24°C, 25°C or any range between the above values) at a rate of 5-15°C / h (for example, 5°C / h, 6°C / h, 8°C / h, 10°C / h, 12°C / h, 14°C / h, 15°C / h or any range between the above values) for recrystallization.

[0053] Preferably, the recrystallization solvent comprises water.

[0054] Preferably, the number of recrystallizations in step (S) is ≥ 1, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 times or a range between any of the above values.

[0055] In the present invention, when the bio-based succinic acid composition is prepared by a recrystallization method, the content of easily oxidizable substances in the bio-based succinic acid is ≤0.6 mL / g.

[0056] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0057] (1) Using biomass resources as raw materials, preparing a succinic acid stock solution having a succinic acid content of 70 to 95 g / L;

[0058] (2) After filtering the succinic acid stock solution obtained in step (1) for the first time, adding a neutralizing agent thereto and mixing for 60 to 120 minutes, filtering for the second time to obtain a filtrate A having a succinic acid content of 65 to 88 g / L;

[0059] (3) mixing the filtrate A obtained in step (2) with the oxidant solution at 60 to 90° C. for 35 to 165 minutes, adding activated carbon thereto and mixing for 30 to 80 minutes to obtain a filtrate B having a succinic acid content of 50 to 65 g / L;

[0060] (4) treating the filtrate B obtained in step (3) with a cation exchange resin and an anion exchange resin to obtain a filtrate C; there is no requirement for the order of the cation exchange resin treatment and the anion exchange resin treatment, and the cation exchange resin treatment and the anion exchange resin treatment may be used in sequence, or the anion exchange resin treatment and the cation exchange resin treatment may be used in sequence; passing the filtrate B through a column filled with one or more cation exchange resins / anion exchange resins one or more times, and adding water (the mass of the filtrate B is 2 to 5 times the mass of the filtrate B) for elution, and collecting the effluent to obtain a filtrate C having a succinic acid content of 10 to 30 g / L;

[0061] The mass of the oxidant solution accounts for 18-50wt% of the mass of the filtrate A, and the concentration of the oxidant solution is 0.02-0.07mol / L; based on the volume of the filtrate A being 1L, the mass of the activated carbon is 5-8g;

[0062] (5) subjecting the filtrate C obtained in step (4) to reduced pressure distillation and cooling crystallization to obtain the bio-based succinic acid composition;

[0063] Or, the preparation method comprises the following steps:

[0064] (S) mixing and dissolving bio-based succinic acid having an oxidizable substance content of ≥0.35 mL / g with a solvent at 60-100° C., then cooling to 15-25° C. at a rate of 5-15° C. / h for recrystallization, filtering, and repeating the above steps at least once to obtain the bio-based succinic acid composition.

[0065] In a third aspect, the present invention provides a polyester, wherein the raw materials for preparing the polyester include the bio-based succinic acid composition described in the first aspect.

[0066] The polyester produced by taking the specific bio-based succinic acid composition of the present invention as raw material has a lower acid value and a higher molecular weight.

[0067] Preferably, the polyester comprises the following components:

[0068] Component A:

[0069] Based on the total molar amount of component A being 100 mol%, the dicarboxylic acid compound comprising the following components:

[0070] a1, 65 to 100 mol % of the bio-based succinic acid composition and / or its ester derivatives described in the first aspect;

[0071] a2, 0 to 35 mol% of adipic acid and / or its ester derivatives;

[0072] and component B: 1,4-butanediol in an amount at least equimolar to component A.

[0073] In the present invention, the molar ratio of component B to component A is (1-3):1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1 or a range between any of the above values; more preferably, it is (1-1.6):1.

[0074] In the present invention, the polyester comprising the following components means that the molecular structure of the polyester contains structural units derived from component A and structural units derived from component B; the dicarboxylic acid compound comprising the following components means that in the molecular structure of the polyester, the dicarboxylic acid structural unit part contains structural units derived from component a1 and structural units derived from component a2.

[0075] In the present invention, 65 to 100 mol%, for example, can be 65 mol%, 66 mol%, 68 mol%, 70 mol%, 72 mol%, 74 mol%, 76 mol%, 78 mol%, 80 mol%, 82 mol%, 84 mol%, 86 mol%, 88 mol%, 90 mol%, 92 mol%, 94 mol%, 96 mol%, 98 mol%, 100 mol% or the range between any of the above values.

[0076] In the present invention, 0-35 mol% can be, for example, 0 mol%, 2 mol%, 4 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, 14 mol%, 16 mol%, 18 mol%, 20 mol%, 22 mol%, 24 mol%, 26 mol%, 28 mol%, 30 mol%, 32 mol%, 34 mol%, 35 mol% or a range between any of the above values.

[0077] Preferably, based on the total molar amount of component A being 100 mol%, the dicarboxylic acid compound comprising the following components:

[0078] a1, 72 to 82 mol% of the bio-based succinic acid composition and / or its ester derivatives described in the first aspect,

[0079] a2, 18 to 28 mol % of adipic acid and / or its ester derivatives.

[0080] In the present invention, the derivatives of succinates include alkyl succinates. For example, the alkyl succinates may be at least one of dimethyl succinate, diethyl succinate, di-n-propyl succinate, diisopropyl succinate, di-n-butyl succinate, diisobutyl succinate, di-tert-butyl succinate, di-n-pentyl succinate, diisopentyl succinate, and di-n-hexyl succinate; the alkyl succinate may be an alkyl ester formed from succinic acid or an alkyl ester formed from succinic anhydride, preferably dimethyl succinate formed from succinic anhydride.

[0081] In the present invention, the derivative of the adipate includes alkyl adipate. For example, the alkyl adipate may be at least one of dimethyl adipate, diethyl adipate, di-n-propyl adipate, diisopropyl adipate, di-n-butyl adipate, diisobutyl adipate, di-tert-butyl adipate, di-n-pentyl adipate, diisopentyl adipate, and di-n-hexyl adipate; the alkyl adipate may be an alkyl ester formed from adipic acid or an alkyl ester formed from adipic anhydride.

[0082] In the present invention, the derivatives of dicarboxylic acids or their esters may be used alone or in admixture of two or more.

[0083] In the present invention, the polyester can be prepared by conventional technical methods in the art. Exemplarily, the method comprises the following steps:

[0084] The components A and B are subjected to an esterification reaction at a temperature of 140 to 220° C. and a pressure of 0.5 to 2 bar for 1 to 6 hours to obtain an esterification product; the esterification product is subjected to a pre-condensation reaction at a temperature of 220 to 270° C. and a pressure of 0.1 to 1 bar for 60 to 140 minutes to obtain a pre-condensation product; the pre-condensation product is subjected to a condensation reaction at a temperature of 230 to 280° C. and a pressure of 1 to 5 mbar for 60 to 100 minutes, pelletized, and dried to obtain the polyester.

[0085] In the present invention, the raw materials for the esterification reaction also include a crosslinking agent, and the crosslinking agent includes at least one of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-trisic acid, 1,2,4-trisic acid, 1,2,4-trisic anhydride, 1,2,4,5-pyromellitic acid or pyromellitic dianhydride; based on the mass of the finished polyester as 100wt%, the mass percentage of the crosslinking agent is 0.05-1wt%.

[0086] In the present invention, the pre-polycondensation reaction also includes a catalyst; the catalyst can be a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound or a titanium compound, more preferably a zinc compound, an aluminum compound or a titanium compound, and most preferably a titanium compound; the titanium compound can be tetrabutyl titanate or tetraisopropyl titanate; the total mass of the catalyst is 0.001 to 1 wt% of the mass of the polycondensation product.

[0087] Preferably, the polyester has an acid number of ≤1.20 mg KOH / g according to standard DIN EN 12634-1998.

[0088] Preferably, according to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, the a value of the polyester is ≤1.5, more preferably ≤1.0, and more preferably ≤0.8.

[0089] Preferably, the intrinsic viscosity of the polyester measured according to GB / T 17931-1999 is ≥1.40 dL / g, more preferably the intrinsic viscosity is ≥1.45 dL / g, and more preferably the intrinsic viscosity is ≥1.60 dL / g.

[0090] The polyesters described in the present invention are also biodegradable.

[0091] For the purposes of the present invention, a substance or a mixture of substances is characterized as "biodegradable" if it shows a percentage degree of biodegradation, as defined in DIN EN 13432, of at least 90%.

[0092] Biodegradation generally results in the decomposition of the polyester or polyester blend within a reasonable period of time. Degradation can occur via enzymatic, hydrolytic or oxidative pathways and / or, by exposure to electromagnetic radiation such as ultraviolet radiation, most often by exposure to microorganisms such as bacteria, yeasts, fungi or algae. Biodegradability can be quantified by mixing the polyester with compost and storing it for a specific period of time. For example, according to DIN EN 13432, during the composting process, CO2-free air is introduced into the mature compost and the compost is subjected to a specific temperature course. Here, biodegradability is defined as the percentage degree of biodegradation expressed as the ratio of the net amount of CO2 released by the sample (after deducting the amount of CO2 released by the compost without the sample) to the maximum amount of CO2 that the sample can release (calculated from the carbon content of the sample).

[0093] Additionally, other methods for determining biodegradability are described in ASTM D5338 and ASTM D6400.

[0094] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] The bio-based succinic acid composition provided by the present invention contains a specific content of easily oxidized substances, which can ensure that the b value of the bio-based succinic acid composition changes little before and after aging, does not affect the production efficiency and process of polyester, and has a long shelf life; the polyester obtained by using the bio-based succinic acid composition as a raw material has a lower acid value, a whiter color and a higher molecular weight. DETAILED DESCRIPTION

[0097] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0098] If not otherwise specified, the raw materials used in the present invention are as follows:

[0099] 1,4-Butanediol: purchased from Xinjiang Meike Chemical Co., Ltd.;

[0100] Glycerin: Purchased from Aladdin;

[0101] Commercially available bio-based succinic acid, first-class specifications: purchased from Shandong Landian Biotechnology Co., Ltd., easily oxidizable content 0.47mL / g;

[0102] Tetrabutyl titanate: purchased from Jianyi Chemical Import & Export Co., Ltd.

[0103] In the present invention, the oxidizable substance content test is carried out with reference to GB / T 34686-2017, and the specific test method is as follows:

[0104] 1) Sample measurement

[0105] Weigh 1.0 g of the sample, accurate to 0.0001 g, add 30 mL of carbon dioxide-free water and 30 mL of sulfuric acid solution (mass fraction is 20%) respectively, and titrate with 0.1 mol / L potassium permanganate standard titration solution until the solution turns pink. The end point is that if it does not completely fade for 3 minutes, the temperature of the sample solution shall not be lower than 55°C during the entire titration process.

[0106] 2) Result calculation

[0107] The oxidizable substance X is expressed as the volume of 0.1 mol / L potassium permanganate standard titration solution consumed per gram of sample, in milliliters per gram (mL / g). The calculation formula is as follows:

[0108]

[0109] in,

[0110] V-the volume of 0.1 mol / L potassium permanganate standard titration solution consumed, in milliliters (mL);

[0111] c-actual concentration of potassium permanganate standard titration solution, in moles per liter (mol / L);

[0112] m-mass of the sample, in grams (g);

[0113] c0-0.1, theoretical concentration of potassium permanganate, in moles per liter (mol / L).

[0114] The arithmetic mean of the two parallel determination results was taken as the result, and the difference between the two parallel determination results should not exceed 5% of the mean value.

[0115] In the present invention, the b value of the bio-based succinic acid composition before and after aging is tested according to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system; wherein the specific method of aging comprises: weighing 20±0.5g of the sample into a weighing bottle, placing the weighing bottle in a blast drying oven at a constant temperature of 150°C, baking for 2 hours, after aging, placing the weighing bottle in a dryer, cooling for 20±2 minutes, and testing the color value b value of the bio-based succinic acid composition after aging according to the standard GB / T14190-2008, using the CIE 1976 (L*a*b*) color system, and calculating the b value change (Δb value).

[0116] In the present invention, the purity of the bio-based succinic acid composition (i.e., the mass percentage of bio-based succinic acid in the bio-based succinic acid composition) is determined by referring to the detailed method specified in 4.3 of standard GB / T 34686-2017.

[0117] In the preparation method of the present invention, the concentration of succinic acid in the obtained succinic acid fermentation broth and filtrate is tested by liquid chromatography. The specific testing method refers to the method disclosed in CN118459331A.

[0118] Example 1

[0119] This embodiment provides a bio-based succinic acid composition, including bio-based succinic acid and an easily oxidized substance, wherein the content of the easily oxidized substance in the bio-based succinic acid composition is 0.18 mL / g.

[0120] This embodiment provides a method for preparing a bio-based succinic acid composition, which specifically comprises the following steps:

[0121] (1) using biomass resources as raw materials, and adopting a microbial fermentation method to prepare a succinic acid fermentation broth having a succinic acid content of 81 g / L, wherein the fermentation broth is prepared by a conventional method in the art, for example, the method described in CN118459331A can be used for preparation;

[0122] (2) filtering the succinic acid fermentation broth obtained in step (1), adding 3 g of a 30% mass concentration Na2CO3 solution to the obtained filtrate, with the volume of the filtrate (succinic acid content of 85.1 g / L) being 1 L, reacting for 80 min under stirring, and filtering to obtain filtrate A;

[0123] (3) adding 0.05 mol / L KMnO4 aqueous solution of 40 wt% by weight to the filtrate A obtained in step (2), heating to 85°C, stirring and reacting for 160 min; then adding activated carbon for decolorization for 60 min, based on the volume of filtrate A being 1 L, the amount of decolorization activated carbon used is 7 g, filtering to obtain filtrate B;

[0124] (4) passing the filtrate B obtained in step (3) through a cation exchange resin column and an anion exchange resin column in sequence, and eluting with water 5 times the weight of the filtrate B, repeatedly washing 4 times, collecting the effluent, and obtaining a filtrate C having a succinic acid content of 16.2 g / L;

[0125] (5) The filtrate C obtained in step (4) is subjected to reduced pressure distillation treatment, the distillation temperature is controlled at 70° C., the pressure is -0.07 to -0.1 MPa, and samples are taken for liquid chromatography testing and moisture testing until the content of succinic acid is greater than 15 wt %, then the distillation is stopped, and the concentrated succinic acid solution is placed at a low temperature (4° C.) for cooling and crystallization to obtain white succinic acid crystals, that is, the bio-based succinic acid composition.

[0126] Example 2

[0127] This embodiment provides a bio-based succinic acid composition, including bio-based succinic acid and an easily oxidized substance, wherein the content of the easily oxidized substance in the bio-based succinic acid composition is 0.23 mL / g.

[0128] This embodiment provides a method for preparing a bio-based succinic acid composition, which specifically comprises the following steps:

[0129] (1) Using biomass resources as raw materials, a succinic acid fermentation liquid was prepared by a microbial fermentation method, and the preparation method was the same as that in Example 1;

[0130] (2) filtering the succinic acid fermentation broth obtained in step (1), adding 2 g of a 25% mass concentration Na2CO3 solution to the obtained filtrate, with the volume of the filtrate (succinic acid content of 83.5 g / L) being 1 L, reacting for 70 min under stirring, and filtering to obtain filtrate A;

[0131] (3) adding 0.05 mol / L KMnO4 solution (30% by weight) to the filtrate A obtained in step (2), heating to 85°C, stirring and reacting for 160 min; then adding activated carbon for decolorization for 60 min, based on the volume of filtrate A being 1 L, the amount of decolorization activated carbon used is 7 g, filtering to obtain filtrate B;

[0132] (4) passing the filtrate B obtained in step (2) through a cation exchange resin column and an anion exchange resin column in sequence, and eluting with water 4 times the weight of the filtrate B, repeatedly washing 3 times, collecting the effluent, and obtaining a filtrate C having a succinic acid content of 19.8 g / L;

[0133] (5) The filtrate C obtained in step (4) is subjected to reduced pressure distillation treatment, the distillation temperature is controlled at 70° C., and the pressure is -0.07 to -0.1 MPa. When the content of succinic acid is greater than 15 wt %, the distillation is stopped, and the concentrated succinic acid solution is placed at a low temperature (4° C.) for cooling and crystallization to obtain white succinic acid crystals, that is, the bio-based succinic acid composition.

[0134] Example 3

[0135] This embodiment provides a bio-based succinic acid composition, including bio-based succinic acid and an easily oxidized substance, wherein the mass of the easily oxidized substance in the bio-based succinic acid composition is 0.28 mL / g.

[0136] This embodiment provides a method for preparing a bio-based succinic acid composition, which specifically comprises the following steps:

[0137] (1) Using biomass resources as raw materials, a succinic acid fermentation liquid was prepared by a microbial fermentation method, and the preparation method was the same as that in Example 1;

[0138] (2) filtering the succinic acid fermentation broth obtained in step (1), adding 3 g of a 30% mass concentration Na2CO3 solution to the obtained filtrate, with the volume of the filtrate (succinic acid content of 84.2 g / L) being 1 L, reacting under stirring for 90 min, and filtering to obtain filtrate A;

[0139] (3) Add 20% by weight of 0.05 mol / L KMnO4 solution to the filtrate A obtained in step (2), heat to 80°C, and stir to react for 40 minutes; then add activated carbon for decolorization for 60 minutes. Based on the volume of filtrate A being 1 L, the amount of decolorization activated carbon used is 6 g, and filter to obtain filtrate B;

[0140] (4) passing the filtrate B obtained in step (3) through a cation exchange resin column and an anion exchange resin column in sequence, and eluting with water 4 times the weight of the filtrate B, repeatedly washing 4 times, collecting the effluent, and obtaining a filtrate C having a succinic acid content of 20.3 g / L;

[0141] (5) The filtrate C obtained in step (4) is subjected to reduced pressure distillation treatment, the distillation temperature is controlled at 70° C., and the pressure is -0.07 to -0.1 MPa. When the content of succinic acid is greater than 15 wt %, the distillation is stopped, and the concentrated succinic acid solution is placed at a low temperature (4° C.) for cooling and crystallization to obtain white succinic acid crystals, that is, the bio-based succinic acid composition.

[0142] Example 4

[0143] This embodiment provides a bio-based succinic acid composition, which differs from Embodiment 1 only in that, in the preparation method, in step (4), the "40% 0.05 mol / L KMnO4 solution" is adjusted to "45% 0.05 mol / L KMnO4 solution", and the other preparation methods are the same as those in Embodiment 1.

[0144] Example 5

[0145] This embodiment provides a bio-based succinic acid composition and a preparation method thereof, wherein the preparation method specifically comprises the following steps:

[0146] (1) adding commercially available bio-based succinic acid at a concentration of 40 g / 100 mL to deionized water at room temperature (23±2° C.), and then heating the deionized water solution containing the bio-based succinic acid to 85° C. to completely dissolve the bio-based succinic acid, thereby forming a bio-based succinic acid aqueous solution;

[0147] (2) cooling the bio-based succinic acid aqueous solution obtained in step (1) to 20±1° C. at a cooling rate of 10° C. / h to allow the bio-based succinic acid to crystallize;

[0148] (3) filtering the solution obtained in step (2) to obtain a bio-based succinic acid product A;

[0149] (4) Repeating the above steps (1) to (3) with the bio-based succinic acid product A obtained in step (3) to obtain the target bio-based succinic acid product, i.e., a bio-based succinic acid composition with a low content of easily oxidized substances.

[0150] Example 6

[0151] This embodiment provides a bio-based succinic acid composition, which differs from Embodiment 1 only in that, in the preparation method, KMnO4 is replaced by a 10% H2O2 aqueous solution which is 40% by mass of filtrate B in step (4), and the other preparation methods are the same as those in Embodiment 1.

[0152] Comparative Example 1

[0153] This comparative example provides a bio-based succinic acid composition, which differs from Example 1 only in that, in the preparation method, step (3) is not performed, and the other preparation methods are the same as those in Example 1.

[0154] Comparative Example 2

[0155] This comparative example provides a bio-based succinic acid composition, which differs from Example 1 only in that, in the preparation method, the "40% 0.05 mol / L KMnO4 solution" in step (3) is adjusted to "15% 0.05 mol / L KMnO4 solution", and the other preparation methods are the same as those in Example 1.

[0156] The test results of the mass percentage of succinic acid, the content of easily oxidized substances, and the b-values ​​before and after aging in the bio-based succinic acid compositions provided in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 1; the remainder in the bio-based succinic acid composition is water and other impurity acids remaining in the process of preparing succinic acid.

[0157] The testing method for the shelf life of the bio-based succinic acid composition includes: placing the bio-based succinic acid composition in a forced air drying oven at 80° C., conducting a thermal oxygen baking experiment, and testing the purity of the bio-based succinic acid composition every 4 hours. When the purity of the bio-based succinic acid composition is lower than 99.0%, the corresponding time is reduced by 4 hours, which is the shelf life of succinic acid. For example, when the purity of succinic acid is lower than 99.0%, the time is 80 hours, and the shelf life is 76 hours.

[0158] Table 1

[0159]

[0160] As can be seen from Table 1, the bio-based succinic acid composition provided by the present invention controls the content of easily oxidized substances within a specific range, so that the bio-based succinic acid can have both aging stability (low Δb value) and a long product shelf life.

[0161] Application Example 1

[0162] This application example provides a polyester, and the preparation method of the polyester includes:

[0163] S1: 187.9 kg of the bio-based succinic acid composition provided in Example 1, 205 kg of 1,4-butanediol and 0.85 kg of glycerol were physically mixed. After the mixing was completed, the obtained mixture was transferred to a multi-stage stirred tank cascade reactor, and the reaction mixture was esterified for 3 hours at a temperature of 180° C. and a pressure of 1.0 bar to obtain an esterified product with an intrinsic viscosity of 0.08 dL / g;

[0164] S2: The esterification product obtained in step S1 is transferred to a vertical reactor with stirring, 0.10 kg of tetrabutyl titanate is added, and the reaction mixture is subjected to a pre-polycondensation reaction at 240° C. and a pressure of 0.35 bar in the reactor for 120 min to obtain a pre-polycondensation product with an intrinsic viscosity of 0.42 dL / g;

[0165] S3: The prepolymer product obtained in step S2 is transferred to a horizontal reactor with stirring, and polycondensed at 243° C. and a pressure of 2.0 mbar for 85 min, pelletized, and dried to obtain the polyester.

[0166] Application Examples 2 to 6, Comparative Application Examples 1 and 2

[0167] Application Examples 2 to 6 and Comparative Application Examples 1 and 2 respectively provide a polyester, which differs from Application Example 1 only in that the bio-based succinic acid composition is provided by Examples 2 to 6 and Comparative Examples 1 and 2 respectively, and other raw materials, amounts and preparation methods are the same as those in Application Example 1.

[0168] Performance Testing

[0169] (1) Intrinsic viscosity: measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C according to the method specified in GB / T 17931-1999.

[0170] (2) Acid value: The acid value AN (mg KOH / g) of the sample was determined according to standard DIN EN 12634-1998.

[0171] The solvent mixture used includes: 1 part by volume of dimethyl sulfoxide, 8 parts by volume of isopropanol, and 7 parts by volume of toluene, and the volume of the solvent mixture is 150 mL.

[0172] The specific method includes: pre-titration of the sample according to the provisions of DIN EN 12634 standard, determining the appropriate sample mass, and ensuring that the volume of the consumed titrant is 2-3mL. Add the sample to the solvent mixture and heat it to 70-85°C to dissolve all the samples into a clear solution. During the titration, keep the solution temperature at 65-75°C to avoid sample precipitation. If appropriate, use tetrabutylammonium hydroxide as the titrant and avoid using highly toxic tetramethylammonium hydroxide. At the same time, in order to prevent the solvent mixture from absorbing CO2 in the air and thus affecting the volume of the blank solvent consumed titrant, when testing the volume of the blank solvent consumed titrant, the blank solvent should be pre-treated according to the same process as the sample test operation, such as heating the blank solvent for the same time and temperature, and then titrating the blank solvent.

[0173] (3) Color value: Standard GB / T 14190-2008, using CIE 1976 (L*a*b*) color system to test the a value of polyester.

[0174] The specific test results are shown in Table 2.

[0175] Table 2

[0176]

[0177] As shown in Table 2, the polyester prepared by using the specific bio-based succinic acid composition of the present invention as a raw material has a low acid value of ≤1.18 mgKOH / g; an intrinsic viscosity of ≥1.46 dL / g, and a higher molecular weight; a color value a≤1.5, and a whiter color.

[0178] From the comparison between the application examples and the comparative application examples, it can be seen that the easily oxidizable substance content of the bio-based succinic acid composition is not within the specific range, the b value changes too much before and after aging, and the aging stability is poor; the obtained polyester has a high acid value, a high color value, a low intrinsic viscosity, and a small molecular weight.

[0179] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bio-based succinic acid composition, characterized in that: The bio-based succinic acid composition comprises bio-based succinic acid and an easily oxidized acid; The content of easily oxidizable substances in the bio-based succinic acid composition is ≤0.32 mL / g.

2. The bio-based succinic acid composition according to claim 1, characterized in that The content of easily oxidizable substances in the bio-based succinic acid composition is 0.01 to 0.29 mL / g.

3. The bio-based succinic acid composition according to claim 1, characterized in that According to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, the b value of the bio-based succinic acid composition is ≤4.2; According to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, the bio-based succinic acid composition has a Δb value of ≤2.5 after aging for 2 hours at 150°C.

4. A method for preparing the bio-based succinic acid composition according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) Using biomass resources as raw materials to prepare succinic acid stock solution; (2) purifying the succinic acid stock solution obtained in step (1) to obtain the bio-based succinic acid composition; The purification method comprises treating with an oxidant solution; the mass of the oxidant solution accounts for 18-50 wt % of the mass of the solution to be treated with the oxidant solution, and the concentration of the oxidant solution is 0.02-0.07 mol / L; or, The preparation method comprises the following steps: (S) Recrystallizing the bio-based succinic acid having an oxidizable substance content of ≥0.35 mL / g and filtering the bio-based succinic acid composition.

5. The preparation method according to claim 4, characterized in that: The mass of the oxidant solution accounts for 20 to 40 wt% of the mass of the solution to be treated with the oxidant solution; The oxidant solution includes at least one of a potassium permanganate aqueous solution, a hydrogen peroxide aqueous solution or a chloric acid solution; The temperature of the treatment with the oxidant solution is 60 to 90° C. and the time is 35 to 165 minutes; The mass concentration of succinic acid in the succinic acid stock solution in step (1) is 70 to 95 g / L.

6. The preparation method according to claim 4, characterized in that: The biomass resources in step (1) include plant resources and / or animal resources; The preparation method in step (1) includes microbial fermentation and / or chemical conversion; The purification method in step (2) further comprises any one of filtering, treating with a neutralizing agent, treating with activated carbon, treating with an ion exchange resin, or a combination of at least two thereof; The time for treating with the neutralizing agent is 60 to 120 minutes; The mass of the activated carbon is 5 to 8 g, based on the volume of the solution to be treated with the activated carbon being 1 L; The ion exchange resin includes a cation exchange resin and / or an anion exchange resin; After the purification in step (2), the process further comprises the steps of reduced pressure distillation and / or cooling crystallization; The recrystallization method in step (S) comprises: mixing bio-based succinic acid with a solvent at 60 to 100° C., and then cooling to 15 to 25° C. at a rate of 5 to 15° C. / h for recrystallization; The solvent in the recrystallization includes water; The number of recrystallizations in step (S) is ≥ 1.

7. The preparation method according to claim 4, characterized in that: The preparation method comprises the following steps: (1) Using biomass resources as raw materials, preparing a succinic acid stock solution with a succinic acid content of 70 to 95 g / L; (2) After filtering the succinic acid stock solution obtained in step (1) for the first time, adding a neutralizing agent thereto and mixing for 60 to 120 minutes, filtering for the second time to obtain a filtrate A having a succinic acid content of 65 to 88 g / L; (3) mixing the filtrate A obtained in step (2) with the oxidant solution at 60 to 90° C. for 35 to 165 minutes, adding activated carbon thereto and mixing for 30 to 80 minutes to obtain a filtrate B having a succinic acid content of 50 to 65 g / L; (4) treating the filtrate B obtained in step (3) with a cation exchange resin and an anion exchange resin to obtain a filtrate C having a succinic acid content of 10 to 30 g / L; The mass of the oxidant solution accounts for 18-50wt% of the mass of the filtrate A, and the concentration of the oxidant solution is 0.02-0.07mol / L; based on the volume of the filtrate A being 1L, the mass of the activated carbon is 5-8g; (5) subjecting the filtrate C obtained in step (4) to reduced pressure distillation and cooling crystallization to obtain the bio-based succinic acid composition; or, The preparation method comprises the following steps: (S) mixing and dissolving bio-based succinic acid having an oxidizable substance content of ≥0.35 mL / g with a solvent at 60-100° C., then cooling to 15-25° C. at a rate of 5-15° C. / h for recrystallization, filtering, and repeating the above steps at least once to obtain the bio-based succinic acid composition.

8. A polyester, characterized in that The raw material for preparing the polyester includes the bio-based succinic acid composition according to any one of claims 1 to 3.

9. The polyester according to claim 8, characterized in that The polyester comprises the following components: Component A: Based on the total molar amount of component A being 100 mol%, the dicarboxylic acid compound comprising the following components: a1, 65 to 100 mol % of the bio-based succinic acid composition and / or its ester derivative according to any one of claims 1 to 3, a2, 0 to 35 mol% of adipic acid and / or its ester derivatives; and Component B: 1,4-butanediol in an amount at least equimolar to that of component A.

10. The polyester according to claim 8, characterized in that According to standard DIN EN 12634-1998, the acid value of the polyester is ≤1.20 mg KOH / g; According to the standard GB / T 14190-2008, using the CIE 1976 (L*a*b*) color system, the a value of the polyester is ≤1.5; The intrinsic viscosity of the polyester measured according to GB / T 17931-1999 is ≥1.40 dL / g.

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