A 1,4-butanediol composition, its preparation method and application

Abstract

This invention provides a 1,4-butanediol composition, its preparation method, and its applications. This invention belongs to the field of polyester preparation technology. The 1,4-butanediol composition comprises 1,4-butanediol, 2,5-dihydrofuran, and Fe element; the mass content of 2,5-dihydrofuran in the 1,4-butanediol composition is ≤50 ppm; the mass content of Fe element in the 1,4-butanediol composition is 0.5~11 ppm. In this invention, the polyester prepared from the 1,4-butanediol composition has a long shelf life, while also ensuring low moisture absorption and good storage resistance.

Description

Technical Field

[0001] This invention belongs to the field of polyester preparation technology, specifically relating to a 1,4-butanediol composition, its preparation method, and its application. Background Technology

[0002] 1,4-Butanediol (hereinafter referred to as "BDO") is an important organic chemical and fine chemical raw material, mainly used in the production of downstream products such as polybutylene terephthalate (PBT), polytetramethylene glycol ether (PTMEG), polyurethane (PU), polybutylene adipate (PBAT), and polybutylene succinate (PBS). Currently, the industrially applied BDO synthesis processes mainly include five methods: the acetylene-aldehyde method, the maleic anhydride method, the allyl alcohol method, the butadiene method, and the bio-based method. For example, it can be obtained from petrochemical-derived raw materials starting from various precursors such as butadiene, acetylene, maleic anhydride, or propylene oxide. Alternatively, it can be produced directly through fermentation using biomass glucose as the main raw material, catalyzed by modified E. coli. Alternatively, bio-based succinic acid can be prepared first by fermenting glucose; then, the bio-based succinic acid reacts with methanol in the presence of a cationic resin to produce monomethyl succinate, which is further reacted with methanol in the presence of a cationic resin to produce dimethyl succinate, which is then hydrogenated in the presence of a copper-based catalyst to produce BDO.

[0003] Whether synthesized via petrochemical or bio-fermentation methods, high levels of 2,5-dihydrofuran impurities may be present during the synthesis of BDO. The presence of high levels of 2,5-dihydrofuran impurities affects the stability of 1,4-butanediol, leading to high moisture absorption during storage. Furthermore, high levels of 2,5-dihydrofuran impurities also result in a short shelf life for polyesters prepared from 1,4-butanediol, specifically manifested in significant changes in the melt index before and after boiling.

[0004] Therefore, developing a 1,4-butanediol that can improve the shelf life of polyester while having a low moisture absorption rate is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a 1,4-butanediol composition, its preparation method, and its applications. This addresses the problems of 1,4-butanediol's hygroscopic nature and the short shelf life of polyesters prepared from it in existing technologies.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a 1,4-butanediol composition comprising 1,4-butanediol, 2,5-dihydrofuran, and Fe element; wherein the mass content of 2,5-dihydrofuran in the 1,4-butanediol composition is ≤50 ppm; and the mass content of Fe element in the 1,4-butanediol composition is 0.5~11 ppm.

[0008] 1,4-Butanediol is prone to side reactions during heat treatment, generating 2,5-dihydrofuran. In this invention, introducing Fe into the 1,4-butanediol composition can suppress the occurrence of 1,4-butanediol side reactions during heat treatment, reduce the mass content of 2,5-dihydrofuran in the 1,4-butanediol composition, and thus give the polyester prepared from the 1,4-butanediol a longer shelf life. If the Fe content is too low, the 2,5-dihydrofuran mass content will be high after heat treatment (such as during polymerization), resulting in a short shelf life for the prepared polyester. If the Fe content is too high, although it can effectively reduce the mass content of 2,5-dihydrofuran in the 1,4-butanediol composition, excessive Fe will enter the polyester along with the 1,4-butanediol reaction, resulting in a high Fe content in the polyester, which also leads to a short shelf life for the prepared polyester, making it difficult to meet practical application requirements.

[0009] In addition, controlling the content of 2,5-dihydrofuran and Fe in the 1,4-butanediol composition within a specific range can reduce the moisture absorption rate of the 1,4-butanediol composition, making it more resistant to storage. If the content of 2,5-dihydrofuran is too high, it will affect the stability of the 1,4-butanediol composition, thus leading to an increase in its moisture absorption rate during storage. If the content of Fe is too high, it will introduce too much impurity, which will also affect the moisture absorption rate of the 1,4-butanediol composition.

[0010] In this invention, the Fe content in the 1,4-butanediol composition is 0.5 to 11 ppm by mass, for example, it can be 0.55 ppm, 0.6 ppm, 0.8 ppm, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm or any range of the above values; preferably 1.5 to 8 ppm.

[0011] In this invention, the Fe content in the 1,4-butanediol composition can be obtained by ICP-OES analysis according to US EPA method 3052:1996.

[0012] Preferably, the iron-containing compound includes a water-soluble iron-containing compound.

[0013] Preferably, the iron-containing compound includes at least one of iron sulfate, iron chloride, iron bromide, and iron nitrate.

[0014] Preferably, the iron-containing compound includes at least one of ferrous sulfate, ferric nitrate, ferrous nitrate, and ferric chloride, more preferably ferric chloride.

[0015] In this invention, the mass content of 2,5-dihydrofuran (DHF) in the 1,4-butanediol composition is ≤50 ppm, for example, it can be 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, 12 ppm, 15 ppm, 18 ppm, 20 ppm, 22 ppm, 25 ppm, 28 ppm, 30 ppm, 32 ppm, 35 ppm, 38 ppm, 40 ppm, 42 ppm, 45 ppm, 48 ppm or any range between the above values, preferably ≤35 ppm, and particularly preferably 3~18 ppm.

[0016] In this invention, controlling the mass content of DHF and Fe elements in the 1,4-butanediol composition within a specific range enables the polyester prepared from the 1,4-butanediol composition to have a longer shelf life. For the art, the lower the DHF content, the better. However, lower DHF content means that more equipment and more complex purification processes are required for refining and purification, leading to increased costs and reduced distillation yield, which is economically disadvantageous.

[0017] In this invention, the DHF content in the 1,4-butanediol composition can be obtained by quantitative analysis using gas chromatography.

[0018] Preferably, the acid value of the 1,4-butanediol composition is ≤0.1 mgKOH / g, for example, it can be 0.001 mgKOH / g, 0.002 mgKOH / g, 0.004 mgKOH / g, 0.006 mgKOH / g, 0.008 mgKOH / g, 0.01 mgKOH / g, 0.02 mgKOH / g, 0.03 mgKOH / g, 0.04 mgKOH / g, 0.05 mgKOH / g, 0.06 mgKOH / g, 0.07 mgKOH / g, 0.08 mgKOH / g, 0.09 mgKOH / g, 0.095 mgKOH / g, or any range of the above values.

[0019] In this invention, the acid value of the 1,4-butanediol composition was tested according to the method in GB / T 6365-2006, specifically: quantitative analysis was performed by titration, using phenolphthalein solution as an indicator and potassium hydroxide solution as a titrant. A certain amount of sample was weighed into an Erlenmeyer flask, and ethanol solution was added to completely dissolve it. An indicator was added, and the solution was titrated with potassium hydroxide solution until a light pink color was obtained and maintained for 30 seconds. At the same time, a blank experiment with ethanol solution was performed. The acid value (mg KOH / g) was calculated using the formula (V-V0)c×56.11 / m, where V and V0 are the volumes (mL) of potassium hydroxide solution consumed by the test sample and blank ethanol, respectively, c is the concentration of potassium hydroxide solution (mol / L), and m is the mass (g) of the test sample.

[0020] Preferably, the 1,4-butanediol composition contains ≥99 wt% 1,4-butanediol, for example, 99.1 wt%, 99.2 wt%, 99.3 wt%, 99.4 wt%, 99.5 wt%, 99.6 wt%, 99.7 wt%, 99.8 wt%, 99.9 wt%, or any range of the above values, more preferably 99.2~99.7 wt%, and particularly preferably 99.5~99.95 wt%.

[0021] In a second aspect, the present invention provides a method for preparing the 1,4-butanediol composition described in the first aspect, the method comprising the following steps:

[0022] (1) The crude 1,4-butanediol product is mixed with an iron-containing compound to obtain a first 1,4-butanediol composition;

[0023] (2) The first 1,4-butanediol composition is post-treated to obtain the 1,4-butanediol composition.

[0024] In the preparation method of this invention, by mixing the crude 1,4-butanediol product with an iron-containing compound and adjusting the content of the iron-containing compound, the content of DHF in the 1,4-butanediol composition can be controlled within a specific range.

[0025] In this invention, the iron-containing compound is mixed with the crude 1,4-butanediol product in the form of an aqueous solution; the concentration of the iron-containing compound in the aqueous solution is 0.01~0.1 mol / L, for example, it can be 0.02 mol / L, 0.05 mol / L, 0.08 mol / L or any range between the above values; based on a mass of 1000g of the crude 1,4-butanediol product, the volume of the aqueous solution of the iron-containing compound is 0.5~30mL, for example, it can be 1 mL, 2 mL, 4 mL, 6 mL, 8 mL, 10 mL, 12 mL, 14 mL, 16 mL, 18 mL, 20 mL, 22 mL, 24 mL, 26 mL, 28 mL or any range between the above values.

[0026] In this invention, the crude 1,4-butanediol product can be commercially available 1,4-butanediol with low purity, or it can be a crude 1,4-butanediol product prepared by conventional methods (such as petrochemical methods, bio-fermentation methods, etc.).

[0027] For example, the crude 1,4-butanediol product can be prepared by the following method, which includes the following steps:

[0028] (1-1) Succinic acid is esterified with an alcohol to obtain succinic acid ester;

[0029] (1-2) The succinate obtained in step (1-1) is subjected to hydrogenation to obtain the crude 1,4-butanediol product.

[0030] In this invention, the succinic acid in step (1-1) can be commercially available or prepared by conventional methods (such as petrochemical methods, bio-fermentation methods, etc., with bio-fermentation methods preferred for environmental protection considerations); the alcohol includes at least one of methanol, ethanol, propanol or butanol.

[0031] In this invention, the esterification reaction is carried out in the presence of a protective atmosphere, which includes, but is not limited to, nitrogen.

[0032] In this invention, the reaction in step (1-1) includes a first esterification reaction and a second esterification reaction.

[0033] In this invention, the first esterification reaction includes placing succinic acid, an alcohol, and an optional esterification catalyst in a reaction vessel; the molar ratio of succinic acid to alcohol is (0.05~6):1, wherein the specific value of (0.05~6) can be, for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.5, 5.8, or any range of the above values; more preferably, it is (0.1~4):1. The esterification catalyst includes, but is not limited to, sulfonic acid resin; the mass of the esterification catalyst is 0.5~5% of the mass of succinic acid, more preferably 3~4%. The temperature of the first esterification reaction is 80~100℃ and the time is 0.5~2h; more preferably, the temperature is 90~100℃ and the time is 0.8~1.5h.

[0034] In this invention, the second esterification reaction includes: introducing alcohol into a reaction vessel after the first esterification reaction has been completed to carry out a second esterification reaction; the amount of alcohol added is 0.5~5 mL / min, for example, it can be 0.5 mL / min, 1 mL / min, 1.5 mL / min, 2 mL / min, 2.5 mL / min, 3 mL / min, 3.5 mL / min, 4 mL / min, 4.5 mL / min, 5 mL / min or any combination thereof, more preferably 2~3 mL / min. The temperature of the second esterification reaction is 100~120℃, the pressure is 0.05~0.5MPa, and the time is 3~8h; more preferably, the temperature is 112~118℃, the pressure is 0.1~0.3MPa, and the time is 3.5~4.5h.

[0035] In this invention, after the esterification reaction described in step (1-1), the process further includes the steps of distilling the crude esterified product obtained from the esterification reaction and adsorbing it with an adsorption resin.

[0036] In this invention, the distillation temperature is 130~142℃ and the pressure is 5~15 kPa; more preferably, the temperature is 135~141℃ and the pressure is 8~12 kPa. The distillation collects the fraction at 114~116℃.

[0037] In this invention, the adsorption is performed by passing the distilled material through an adsorption column packed with adsorption resin, and the space velocity of the material is controlled at 0.5~2 h⁻¹ during adsorption. -1 A preferred airspeed is 0.8~1.5h. -1 .

[0038] In this invention, the temperature of the hydrogenation reaction in step (1-2) is 150~182℃, the hydrogen flow rate is 180~350L / h, and the pressure is 4~10MPa; more preferably, the temperature is 160~181℃, the hydrogen flow rate is 220~270L / h, and the pressure is 6.5~7.5MPa.

[0039] In this invention, the feed flow rate of the succinate during the hydrogenation reaction in step (1-2) is 0.05~0.3 mL / min, more preferably 0.1~0.21 mL / min.

[0040] In this invention, the hydrogenation reaction described in step (1-2) is carried out in the presence of a hydrogenation catalyst.

[0041] Preferably, the crude 1,4-butanediol product in step (1) contains ≥98% 1,4-butanediol by mass and ≥100 ppm 2,5-dihydrofuran by mass.

[0042] In this invention, the post-processing in step (2) includes distillation.

[0043] Preferably, the distillation temperature is 180~190℃ and the pressure is 2~10KPa; more preferably, the temperature is 183~189℃ and the pressure is 3~7KPa; particularly preferably, the temperature is 184~188℃ and the pressure is 4.5~6.5KPa.

[0044] Preferably, the distillation collects a fraction at 150-160°C, more preferably a fraction at 153-158°C, and particularly preferably a fraction at 154-156°C.

[0045] Preferably, the number of distillations is ≥1, for example, 1, 2, 3, 4, 5, 6, or any range of the above values.

[0046] In a second aspect, the present invention provides the use of the 1,4-butanediol composition described in the first aspect in the preparation of polyester.

[0047] Thirdly, the present invention provides a polyester, wherein the raw materials for preparing the polyester include the 1,4-butanediol composition described in the first aspect.

[0048] Preferably, the polyester includes at least one of aliphatic-aromatic polyester and aliphatic polyester.

[0049] In this invention, the aliphatic-aromatic polyester comprises a polyester formed by polycondensation of a diacid and / or its derivative with the 1,4-butanediol composition; the diacid and / or its derivative comprises at least one aromatic diacid and / or its derivative and at least one aliphatic diacid and / or its derivative; the aromatic diacid and / or its derivative includes, but is not limited to, at least one of terephthalic acid and / or its derivative, isophthalic acid and / or its derivative, and furanyl dicarboxylic acid and / or its derivative; the aliphatic diacid and / or its derivative includes, but is not limited to, oxalic acid and / or its derivative, malonic acid and / or its derivative, succinic acid and / or its derivative, adipic acid and / or its derivative, pimelic acid and / or its derivative, azelaic acid and / or its derivative, sebacic acid and / or its derivative, etc.

[0050] Preferably, the aliphatic-aromatic polyester comprises diacid residues and diol residues; in molar percentage, the diacid residues comprise 30-70 mol% of terephthalic acid residues and 30-70 mol% of at least one C4-C10 aliphatic diacid residue; the diol residues are derived from the 1,4-butanediol composition.

[0051] In this invention, 30-70 mol% of terephthalic acid residues can be, for example, 32 mol%, 35 mol%, 38 mol%, 40 mol%, 42 mol%, 45 mol%, 48 mol%, 50 mol%, 52 mol%, 55 mol%, 58 mol%, 60 mol%, 62 mol%, 65 mol%, 68 mol%, or any of the above values.

[0052] In this invention, at least one C4-C10 aliphatic dicarboxylic acid residue, in the range of 30-70 mol%, can be, for example, 32 mol%, 35 mol%, 38 mol%, 40 mol%, 42 mol%, 45 mol%, 48 mol%, 50 mol%, 52 mol%, 55 mol%, 58 mol%, 60 mol%, 62 mol%, 65 mol%, 68 mol%, or any of the above values.

[0053] In this invention, the C4-C10 aliphatic dicarboxylic acid residues can be, for example, C4, C5, C6, C7, C8, C9, and C10 aliphatic dicarboxylic acid residues. Exemplarily, they include, but are not limited to, at least one of succinic acid residues, adipic acid residues, azelaic acid residues, and sebacic acid residues, preferably adipic acid residues and / or sebacic acid residues; the same expressions in the following text have the same meaning.

[0054] In this invention, the aliphatic polyester comprises a polyester formed by polycondensation of an aliphatic diacid and / or its derivatives with the 1,4-butanediol composition; the aliphatic diacid and / or its derivatives include, but are not limited to, oxalic acid and / or its derivatives, malonic acid and / or its derivatives, succinic acid and / or its derivatives, adipic acid and / or its derivatives, pimelic acid and / or its derivatives, azelaic acid and / or its derivatives, sebacic acid and / or its derivatives, etc.

[0055] Preferably, the aliphatic polyester comprises diacid residues and diol residues; in molar percentage, the diacid residues comprise 60-100 mol% succinic acid residues and 0-40 mol% at least one C6-C10 aliphatic diacid residue; the diol residues are derived from the 1,4-butanediol composition.

[0056] In this invention, 60-100 mol% of succinic acid residues can be, for example, 60 mol%, 61 mol%, 62 mol%, 63 mol%, 64 mol%, 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 any of the above values; more preferably, 72-82 mol%.

[0057] In this invention, at least one C6-C10 aliphatic dicarboxylic acid residue, ranging from 0 to 40 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%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, or any of the above values, more preferably 18 to 28 mol%.

[0058] It should be noted that the term "residue" refers to any organic structure introduced into the polymer molecular chain by the relevant monomer through a polycondensation reaction, that is, an organic structure derived from the relevant monomer; for example, diacid residues refer to structures in polyester derived from diacid monomers and / or diacid derivatives.

[0059] In this invention, the derivatives of diacids (including derivatives of aromatic diacids and derivatives of aliphatic diacids) refer to esters; for example, the derivatives of diacids are selected from alkyl esters of diacids. For example, the alkyl ester can be at least one of dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, and di-n-hexyl ester; the alkyl ester can be an alkyl ester formed from a diacid or an alkyl ester formed from a diacid anhydride.

[0060] In this invention, according to standard ISO 1133-2-2012, under the conditions of 190°C and 2.16 kg, the melt index of the polyester is ≤30 g / 10 min, preferably 2~12 g / 10 min, and more preferably 3~8 g / 10 min.

[0061] In this invention, it is more preferable that the melt index of the aliphatic-aromatic polyester is ≤10 g / 10 min, and even more preferably that the melt index of the aliphatic-aromatic polyester is 3~6 g / 10 min.

[0062] In this invention, the polyester, after being boiled in distilled water at 95°C for 3 hours, exhibits a melt index change rate η ≤ 72%, preferably η ≤ 50%; more preferably η ≤ 30%.

[0063] In this invention, the aliphatic polyester and aliphatic-aromatic polyester can be prepared using methods conventional in the art. For example, the method includes the following steps:

[0064] S1: A dicarboxylic acid, a diol, a crosslinking agent, and a catalyst are mixed and esterified at 165~235℃ and 0.5~1.5 bar for 3~5 hours to obtain the esterified product.

[0065] S2: The esterified product is prepolymerized at 235~255℃ and 0.1~0.5 bar for 50~90 min to obtain the prepolymerized product;

[0066] S3: The prepolymer product is subjected to polycondensation reaction at 240~260℃ and 1~5mbar for 150~170min, sliced, and dried to obtain the polyester.

[0067] In this invention, the diacid can be a diacid derivative, and the molar ratio of the diacid to the diol is 1:(1.4~3); the mass of the crosslinking agent is 0.1~1wt% of the mass of the diacid, more preferably 0.3~0.7wt%; the crosslinking agent includes, but is not limited to, tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzotriic acid, 1,2,4-benzotriic acid, 1,2,4-benzotriic anhydride, 1,2,4,5-benzotetraic acid, benzopyrene dianhydride, etc.; the mass of the catalyst is 0.05~0.2wt% of the mass of the diacid, more preferably 0.08~0.15wt%; the catalyst includes, but is not limited to, tetrabutyl titanate or tetraisopropyl titanate, etc.

[0068] The aliphatic polyesters and aliphatic-aromatic polyesters described in this invention are biodegradable.

[0069] For the purposes of this invention, a substance or mixture of substances is considered "biodegradable" if it exhibits a biodegradability of at least 90%, as defined in DIN EN 13432.

[0070] Biodegradation typically results in the breakdown of polyester or polyester blends within a reasonable observation period. Degradation can occur via enzymatic, hydrolytic, or oxidative pathways, and / or through exposure to electromagnetic radiation such as ultraviolet radiation, and most commonly through exposure to microorganisms such as bacteria, yeast, fungi, or algae. Biodegradability can be quantified by mixing polyester with compost and storing it for a specific period. For example, according to DIN EN 13432, during composting, CO2-free air is introduced into the maturing compost, and the compost is subjected to a specific temperature process. Here, biodegradability is defined as the percentage degree of biodegradation expressed as the ratio of the net amount of CO2 released by the sample (minus the amount of CO2 released by compost without the sample) to the maximum amount of CO2 that the sample can release (calculated from the carbon content in the sample).

[0071] In addition, other methods for determining biodegradability are described in ASTM D5338 and ASTM D6400.

[0072] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] The 1,4-butanediol composition provided by the present invention contains a specific amount of Fe element and 2,5-dihydrofuran, which makes the 1,4-butanediol composition have a low moisture absorption rate, and the polyester prepared from the 1,4-butanediol composition has a long shelf life and a small change rate of melt index before and after boiling. Detailed Implementation

[0075] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0076] All materials used in this invention are commercially available or prepared using conventional methods. Unless otherwise specified, the raw materials used in this invention are as follows:

[0077] 1,4-Butyric acid was purchased from Liaoning Kingfa Biomaterials Co., Ltd.

[0078] Glycerin, purchased from Aladdin.

[0079] Tetrabutyl titanate was purchased from Jianyi Chemical Import & Export Co., Ltd.

[0080] Commercially available bio-based 1,4-butanediol: purchased from Zhejiang Boju New Materials Co., Ltd., with a mass percentage of 99.72%, DHF content of 121 ppm, and Fe content of ND.

[0081] Esterification catalyst: DT-01 strong acid resin, purchased from Dandong Mingzhu Special Resin Co., Ltd.

[0082] Hydrogenation catalyst: CuCAT-2400T, purchased from Shanghai Xunkai New Material Technology Co., Ltd.

[0083] Adsorption resin: Amberlyst 40wet macroporous styrene resin.

[0084] In this invention, the specific testing methods for the content of 1,4-butanediol, Fe content, DHF content, and acid value in the 1,4-butanediol composition are as follows.

[0085] 1. 1,4-Butanediol content test

[0086] In this invention, the method for testing the mass content of 1,4-butanediol in the 1,4-butanediol composition includes: quantitative analysis by gas chromatography according to GB / T 24768-2009; preparation of a standard solution of 1,4-butanediol; testing the correction coefficient of impurities relative to 1,4-butanediol; taking the correction coefficient of unknown impurities as 1; and calculating the content of 1,4-butanediol by the correction integral area.

[0087] 2. Fe content test

[0088] In this invention, the Fe content in the 1,4-butanediol composition was tested according to US EPA Method 3052:1996, using ICP-OES analysis. The procedure was as follows: approximately 0.1 g of the 1,4-butanediol composition was weighed, and 5 mL of nitric acid was added to completely submerge the composition. Then, 1.0 mL of hydrogen peroxide was added dropwise and reacted for 2 min. The mixture was then sealed in a microwave digestion vessel and digested at 210°C for 3 hours. After cooling to room temperature, the mixture was filtered through a 0.45 μm filter membrane and diluted with distilled water to 50 mL. The result was then tested using ICP-OES. ND indicates that the content of the relevant element was not detected.

[0089] 3. DHF content test

[0090] In this invention, the method for testing the DHF content in the 1,4-butanediol composition includes: quantitative analysis using gas chromatography; preparation of a DHF standard solution; and establishment of peak area-weight content standard curves using a gas chromatograph (Agilent 8860 GC, manufactured by Agilent Technologies (China) Co., Ltd.). The DHF content in the 1,4-butanediol composition is calculated from the obtained peak area and the standard curves. The chromatographic column is an Agilent J&W CP-Sil 8 CB, the detection temperature is 60~280℃, and a gradient temperature increase is used. The specific temperature increase program is shown in Table 1. The solvent for the standard solution is ethanol.

[0091] Table 1

[0092]

[0093] Example 1

[0094] This embodiment provides a 1,4-butanediol composition, and the specific preparation method of the 1,4-butanediol composition includes the following steps:

[0095] (1-1) 413g of 1,4-succinic acid, 360g of methanol and 18g of esterification catalyst were added to a high-pressure reactor according to the metered amount. Nitrogen was used to purge the reactor and the temperature was raised to 95℃ for 1h (first esterification). Then the temperature was raised to 115℃, the gas phase was collected by turning on the condenser at the top of the high-pressure reactor, and methanol was added to the high-pressure reactor at a metered amount of 2.5mL / min using a horizontal flow pump. The pressure inside the reactor was controlled at 0.22MPa. The reaction was continued for 5h (second esterification) and then the addition of methanol was stopped. All the methanol and water produced in the reactor were evaporated to complete the succinic acid esterification reaction and dimethyl succinate was obtained, which was denoted as crude dimethyl succinate.

[0096] The crude dimethyl succinate was purified by distillation, with the material temperature controlled at 136-140℃ and the pressure at 10 kPa. The fraction at 114-116℃ was collected and passed into an adsorption column packed with Amberlyst 40wet macroporous styrene resin for adsorption, with the material space velocity controlled at 1 h⁻¹. -1 The purified dimethyl succinate was obtained and is denoted as purified dimethyl succinate.

[0097] (1-2) The dimethyl succinate was added to a fixed-bed reactor containing a hydrogenation catalyst using a metering pump at a flow rate of 0.20 mL / min. The hydrogen flow rate was controlled at 250 L / h, the reaction temperature at 180 °C, and the pressure at 6.7 MPa to carry out the hydrogenation reaction, and 1,4-butanediol was obtained, which was denoted as crude 1,4-butanediol (1,4-butanediol mass percentage content was 98.32%, acid value was 0.38 mg KOH / g, and DHF content was 138 ppm).

[0098] (2) 10 mL of 0.05 mol / L ferric chloride aqueous solution was gradually added to 1000 g of crude 1,4-butanediol to obtain the first 1,4-butanediol composition;

[0099] (3) The first 1,4-butanediol composition is purified by negative pressure distillation three times. During the distillation process, the material temperature is controlled at 184~188℃ and the tower pressure is 5.0KPa. The fraction at 154~156℃ is collected to obtain the purified 1,4-butanediol composition, which is the 1,4-butanediol composition.

[0100] Example 2

[0101] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 4 mL in step (2), and the other steps are the same as in Example 1.

[0102] Example 3

[0103] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 22 mL in step (2), and the other steps are the same as in Example 1.

[0104] Example 4

[0105] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the distillation in step (3) is performed twice, and the other steps are the same as in Example 2.

[0106] Example 5

[0107] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 1.6 mL in step (2), and the other steps are the same as in Example 1.

[0108] Example 6

[0109] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 16 mL in step (2), and the other steps are the same as in Example 1.

[0110] Example 7

[0111] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the ferric chloride aqueous solution in step (2) is replaced with an aqueous solution of ferrous sulfate of equal mass of Fe (concentration of 0.05 mol / L), and the other steps are the same as in Example 1.

[0112] Example 8

[0113] This embodiment provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, steps (1-1) and (1-2) are omitted. The crude 1,4-butanediol product in step (2) is replaced with commercially available 1,4-butanediol. The other steps are the same as in Example 1.

[0114] Comparative Example 1

[0115] This comparative example provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, step (2) is omitted, and the other steps are the same as in Example 1.

[0116] Comparative Example 2

[0117] This comparative example provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 0.5 ml in step (2), the distillation purification is performed 6 times in step (3), and the other steps are the same as in Example 1.

[0118] Comparative Example 3

[0119] This comparative example provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, the volume of the ferric chloride aqueous solution is adjusted to 30 ml in step (2), and the other steps are the same as in Example 1.

[0120] Comparative Example 4

[0121] This comparative example provides a 1,4-butanediol composition. In the preparation method of the 1,4-butanediol composition, in step (2), the ferric chloride aqueous solution is replaced with an aqueous solution of calcium chloride of equal metal mass (concentration of 0.05 mol / L), and the other steps are the same as in Example 1.

[0122] Comparative Example 5

[0123] This comparative example provides a 1,4-butanediol, which is a commercially available bio-based 1,4-butanediol.

[0124] Comparative Example 6

[0125] This comparative example provides a 1,4-butanediol composition, the preparation method of which includes: adding 0.05 mol / L ferric chloride aqueous solution to the 1,4-butanediol composition obtained in Example 1, so that the composition of the 1,4-butanediol composition is as shown in Table 3.

[0126] In this invention, the compositions of the 1,4-butanediol compositions provided in Examples 1 to 8 are shown in Table 2; the compositions of the 1,4-butanediol compositions provided in Comparative Examples 1 to 6 are shown in Table 3.

[0127] Table 2

[0128]

[0129] Table 3

[0130]

[0131] Application examples

[0132] This application example provides a polyester, the raw materials for which include 350 kg of a 1,4-butanediol composition, 327 kg of succinic acid, 1.8 kg of glycerol, and 0.38 kg of tetrabutyl titanate; the method for preparing the polyester includes the following steps:

[0133] S1: Succinic acid, 1,4-butanediol and glycerol are physically mixed. After mixing, the resulting mixture is transferred to an esterification reactor and esterified for 4 h at a temperature of 170°C and a pressure of 1.0 bar to obtain the esterified product.

[0134] S2: The esterification product obtained in step S1 is transferred to a vertical reactor with a stirrer, tetrabutyl titanate is added, and the reaction mixture is pre-polymerized at 250°C and 0.3 bar for 70 min to obtain the pre-polymerized product.

[0135] S3: The prepolymer obtained in step S2 is transferred to a horizontal reactor with a stirrer and subjected to polycondensation reaction at a temperature of 253°C and a pressure of 2.5 mbar for 160 min. The product is then sliced, dried, and the polyester is obtained. The 1,4-butanediol compositions are the 1,4-butanediol compositions provided in the examples and comparative examples, respectively.

[0136] Performance testing

[0137] The shelf life of the polyester prepared from the 1,4-butanediol composition was tested.

[0138] The shelf life of the polyester is assessed by the melt flow index change rate η. The specific assessment method is as follows: According to standard ISO 1133-2-2012, under conditions of 190°C and 2.16 kg, the initial melt flow index of the polyester is tested and recorded as MFR0. Then, the polyester is placed in distilled water at 95°C and boiled for 3 hours, followed by vacuum drying at 60°C for 6 hours. The melt flow index of the polyester after boiling is then tested and recorded as MFR1. The melt flow index change rate is calculated according to formula I.

[0139] .

[0140] The larger the melt flow index change rate η, the shorter the shelf life of the polyester.

[0141] The moisture absorption rate γ of the 1,4-butanediol composition was tested using the following method: 25 mL of the 1,4-butanediol composition was placed in a 50 mL beaker. The beaker was left open and stored at 25±2℃ and 50±5% humidity for 4 hours. The moisture content before and after moisture absorption was tested according to ISO 15512 Method C. The moisture content before moisture absorption was recorded as w1, and the moisture content after 4 hours of storage was recorded as w2. The moisture absorption rate γ was calculated using the following formula:

[0142] .

[0143] The lower the moisture absorption rate γ, the better the storage resistance of the 1,4-butanediol composition. Specific test results are shown in Table 4.

[0144] Table 4

[0145]

[0146] As shown in Table 4, the 1,4-butanediol composition provided by the present invention, by controlling the mass content of Fe and 2,5-dihydrofuran in the 1,4-butanediol composition within a specific range, results in a low moisture absorption rate. When stored openly at 25±2℃ and 50±5% humidity for 4 hours, the moisture absorption rate is ≤330%, and the polyester prepared from it has a long shelf life. The polyester prepared from the 1,4-butanediol composition, after being boiled in distilled water at 95℃ for 3 hours, has a melt index change rate η ≤72%.

[0147] As can be seen from Comparative Example 1, the 1,4-butanediol composition does not contain Fe element, has a high DHF content, and the resulting polyester has an increased melt index change rate after boiling and a shorter shelf life; moreover, the 1,4-butanediol composition has a high moisture absorption rate.

[0148] As can be seen from Comparative Example 2, the DHF content is within the range defined by this invention, but the Fe element content is too low. The melt index change rate of the polyester prepared from the 1,4-butanediol composition increases, and the shelf life is short.

[0149] As can be seen from Comparative Examples 3 and 6, if the Fe content is too high, the moisture absorption rate of the 1,4-butanediol composition is high. At the same time, the melt index change rate of the polyester prepared from the 1,4-butanediol composition increases and the shelf life is short.

[0150] As shown in Comparative Example 4, when Fe is replaced with other metal elements (such as calcium), the DHF content in the 1,4-butanediol composition is higher, the melt index change rate of the prepared polyester increases, and the 1,4-butanediol composition has a high moisture absorption rate.

[0151] As can be seen from Comparative Example 5, the 1,4-butanediol composition provided by the present invention has a lower moisture absorption rate and the polyester prepared therefrom has a lower melt index change rate compared to commercially available 1,4-butanediol.

[0152] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A 1,4-butanediol composition, characterized in that, The 1,4-butanediol composition comprises 1,4-butanediol, 2,5-dihydrofuran, and Fe element; The mass content of 2,5-dihydrofuran in the 1,4-butanediol composition is ≤50 ppm. The Fe content in the 1,4-butanediol composition is 0.5~11 ppm by mass.

2. The 1,4-butanediol composition according to claim 1, characterized in that, The Fe content in the 1,4-butanediol composition is 1.5~8 ppm by mass.

3. The 1,4-butanediol composition according to claim 1, characterized in that, The Fe element is derived from iron-containing compounds; The iron-containing compounds include water-soluble iron-containing compounds.

4. The 1,4-butanediol composition according to claim 3, characterized in that, The iron-containing compound includes at least one of iron sulfate, iron chloride, iron bromide, and iron nitrate.

5. The 1,4-butanediol composition according to claim 4, characterized in that, The iron-containing compound includes at least one of ferrous sulfate, ferric nitrate, ferrous nitrate, and ferric chloride.

6. The 1,4-butanediol composition according to claim 1, characterized in that, The mass content of 2,5-dihydrofuran in the 1,4-butanediol composition is ≤35 ppm; The 1,4-butanediol composition contains ≥99 wt% 1,4-butanediol.

7. A method for preparing a 1,4-butanediol composition according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: (1) The crude 1,4-butanediol product is mixed with an iron-containing compound to obtain a first 1,4-butanediol composition; (2) The first 1,4-butanediol composition is post-treated to obtain the 1,4-butanediol composition; In step (1), the crude 1,4-butanediol product contains ≥98% 1,4-butanediol by mass and ≥100 ppm 2,5-dihydrofuran by mass.

8. The use of a 1,4-butanediol composition according to any one of claims 1 to 6 in the preparation of polyesters.

9. A polyester, characterized in that, The raw materials for preparing the polyester include the 1,4-butanediol composition according to any one of claims 1 to 6; The polyester includes at least one of aliphatic-aromatic polyester and aliphatic polyester.

10. The polyester according to claim 9, characterized in that, The aliphatic-aromatic polyester includes diacid residues and diol residues; Based on molar percentage, the dicarboxylic acid residue comprises 30-70 mol% of terephthalic acid residue and 30-70 mol% of at least one C4-C10 aliphatic dicarboxylic acid residue; The diol residues are derived from the 1,4-butanediol composition; The aliphatic polyester includes diacid residues and diol residues; Based on molar percentage, the dicarboxylic acid residue comprises 60-100 mol% succinic acid residue and 0-40 mol% at least one C6-C10 aliphatic dicarboxylic acid residue; The diol residues are derived from the 1,4-butanediol composition.

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