Synthesis method of high value-added bio-based poly (butylene succinate) (PBS)

Abstract

The invention discloses a synthetic method of high-added-value bio-based poly (butylene succinate) (PBS), and relates to the technical field of poly (butylene succinate) synthesis. The solvent has a good fusion effect: acetonitrile and toluene can obtain a product with high weight-average molecular weight, n-hexane can obtain a product with high weight-average molecular weight and low polydispersity coefficient, and the synthesis effect and quality can be ensured; the catalytic effect is good; the poly (butylene succinate) of which the number-average molar mass is 5.7 * 10 < 4 >-8.0 * 10 < 4 > g / mol can be prepared by using the titanium catalyst; the efficient composite catalyst is generally composed of multiple components such as amino acid or amino-acid ester, titanate, silicate ester and metal acetate, the catalysts are subjected to esterification reaction, pre-polycondensation reaction and final polycondensation reaction, poly (butylene succinate) with good intrinsic viscosity and good acid value is prepared, the catalysis effect and quality can be guaranteed, and the catalyst is suitable for industrial production. The synthesis quality of the poly (butylene succinate) can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of polybutylene succinate synthesis, and particularly relates to a method for synthesizing high-value-added bio-based polybutylene succinate PBS. Background Art

[0002] Polybutylene succinate (PBS) is a high-value-added bio-based polybutylene succinate, which is a polymer obtained by the polycondensation reaction of succinic acid and butanediol. PBS has various excellent properties, such as good degradability, biocompatibility and processability, so it has a wide range of applications in many fields.

[0003] For example, the patent with the publication number CN114163626B synthesizes PBS using a titanium-based catalyst, but the number-average molecular weight of its product is only 4.5×10 4 g / mol, and corrosive aids (such as phosphoric acid) need to be used. In contrast, through the synergistic effect of n-hexane solvent and an efficient composite catalyst in the present invention, the number-average molecular weight can be increased to 5.7×10 4 ~8.0×10 4 g / mol, and corrosive aids are not required, and the treatment cost of the polycondensation distillate is reduced by 60%. Although the international patent US2020 / 0387145A1 mentions the synthesis of bio-based PBS, it does not disclose the influence of solvent selection on the polydispersity index of the product. However, in the present invention, using n-hexane, the PDI can be controlled below 1.2 (the industry average is 1.8). Therefore, we propose a method for synthesizing high-value-added bio-based polybutylene succinate PBS. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for synthesizing high-value-added bio-based polybutylene succinate PBS to solve the problems mentioned in the above background art.

[0005] The present invention specifically adopts the following technical solutions to achieve the above purpose:

[0006] A method for synthesizing high-value-added bio-based polybutylene succinate PBS, comprising the following steps:

[0007] Step 1, raw material preparation: succinic acid, butanediol, catalyst, solvent;

[0008] Step 2, stirring and mixing: placing the raw materials in a mixer for mixing and stirring;

[0009] Step 3, esterification reaction: carrying out an esterification reaction on succinic acid and butanediol;

[0010] Step 4, polycondensation reaction: carrying out a polycondensation reaction on the mixture after the esterification reaction is completed;

[0011] Step 5, Separation and purification: Separate the mixture after the polycondensation reaction, remove the impurities therein, and perform purification work to obtain poly(butylene succinate).

[0012] Further, the solvent in Step 1 is selected from one of acetonitrile, tetrahydrofuran, toluene, and n-hexane.

[0013] Further, the catalyst in Step 1 is selected from one of titanium-based catalysts, highly efficient composite catalysts, and dual catalyst systems. Among them, the highly efficient composite catalyst is composed of amino acid ester (20 - 30%), titanate (40 - 50%), silicate (15 - 25%), and metal acetate (5 - 10%) by mass ratio.

[0014] Further, the molar ratio of amino acid ester to titanate in the highly efficient composite catalyst is 1:3 - 1:5. The metal acetate, as an active site promoter, can increase the esterification reaction rate by more than 40%.

[0015] Further, in the dual catalyst system, the main catalyst is a titanium-based catalyst (accounting for 70 - 80%), and the co-catalyst is a metal hydroxide (such as Mg(OH) 2 ), and their synergistic effect can shorten the polycondensation reaction time to 1.5 hours, and the number average molecular weight of the product is increased to 8.0×10 4 g / mol.

[0016] Further, the stirring and mixing temperature in Step 2 is 130 - 150°C, and it is depressurized to -10°C using a vacuum pump.

[0017] Further, the esterification reaction temperature in Step 3 is 130 - 170°C. The esterification reaction pressure is carried out under normal pressure or inert gas protection, and the esterification reaction time is 1 - 3 hours.

[0018] Further, the polycondensation reaction temperature in Step 4 is 200 - 230°C, the polycondensation reaction pressure is 10 - 100 Pa, and the polycondensation reaction time is 1 - 5 hours.

[0019] Further, the separation and purification in Step 5 include the following steps:

[0020] Step 51, Pretreatment: Remove the organic solvent by water bath heating (50°C), then extract in ethanol for 2 hours, filter, and crystallize at -10°C for 12 hours;

[0021] Step 52, Washing: Wash 3 times with toluene (purity ≥ 99.5%) for 10 minutes each time to remove chloride ions and unreacted monomers;

[0022] Step 53, Drying: Dry in a vacuum drying oven (temperature 60°C, pressure -10°C) for 4 hours.

[0023] Further, toluene is selected as the organic solvent in the washing step 52.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The solvent fusion effect of the present invention is excellent: acetonitrile and toluene can obtain products with high weight-average molecular weight, and n-hexane can obtain products with high weight-average molecular weight and low polydispersity coefficient, which can ensure the synthesis effect and quality.

[0026] 2. The catalytic effect of the present invention is excellent: using a titanium-based catalyst, poly(butylene succinate) with a number-average molar mass between 5.7×10^4 and 8.0×10^4 g / mol can be prepared; the highly efficient composite catalyst usually consists of multiple components, such as amino acids or amino acid esters, titanates, silicates, and metal acetates, etc. These catalysts are used to prepare poly(butylene succinate) with an intrinsic viscosity ≥1.8 dL·g^-1, L value (lightness value) ≥85, and acid value ≤10 mol / t through esterification reaction, pre-polycondensation reaction, and final polycondensation reaction, which can ensure the catalytic effect and quality, that is, it can ensure the synthesis quality of poly(butylene succinate).

[0027] 3. The process of the present invention optimizes the solvent and catalyst synergistically, combined with highly efficient separation and purification technology, reducing the industrial production cost to 8,000 - 10,000 yuan / ton, which is more than 70% lower than the traditional process (33,000 yuan / ton), and is significantly better than the current mainstream products in the market (35,000 - 40,000 yuan / ton), having outstanding economic competitiveness. This cost advantage comes from: (1). The n-hexane solvent improves the molecular weight and dispersity of the product, reducing the energy consumption of post-treatment; (2). The highly efficient composite catalyst increases the esterification rate by 40% and reduces the catalyst dosage by 30%; (3). The vacuum drying process shortens the purification cycle to 4 hours and increases the production efficiency by 60%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a process schematic diagram of the present invention;

[0029] Figure 2 is a process schematic diagram of separation and purification in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] Please refer to Figure 1 - Figure 2 , the present invention provides a method for synthesizing high-value-added bio-based poly(butylene succinate) PBS, including the following steps:

[0032] Step 1, Raw material preparation: succinic acid, butanediol, catalyst, solvent;

[0033] Step 2, Stirring and mixing: Place the raw materials in a mixer for mixing and stirring;

[0034] Step 3, Esterification reaction: Carry out an esterification reaction on succinic acid and butanediol;

[0035] Step 4, Polycondensation reaction: Carry out a polycondensation reaction on the mixture after the esterification reaction is completed;

[0036] Step 5, Separation and purification: Separate the mixture after the polycondensation reaction is completed, remove the impurities therein, and carry out purification work to obtain polybutylene succinate.

[0037] Preferably, the solvent in Step 1 is selected from one of acetonitrile, tetrahydrofuran, toluene, and n-hexane.

[0038] Acetonitrile is a low-boiling solvent, suitable for the synthesis of polybutylene succinate, and can obtain a product with a high weight-average molecular weight; tetrahydrofuran is another low-boiling solvent, also suitable for the synthesis of polybutylene succinate; toluene is a commonly used organic solvent, which can be used for the synthesis of polybutylene succinate and can obtain a product with a high weight-average molecular weight; n-hexane is a low-boiling solvent, which can obtain a product with a high weight-average molecular weight and a low polydispersity coefficient. Therefore, no matter which one of acetonitrile, tetrahydrofuran, toluene, and n-hexane is selected, it is beneficial to prepare polybutylene succinate.

[0039] Preferably, the catalyst in Step 1 is selected from one of titanium-based catalysts, highly efficient composite catalysts, and dual catalyst systems. Among them, the highly efficient composite catalyst is composed of amino acid ester (20 - 30%), titanate (40 - 50%), silicate (15 - 25%), and metal acetate (5 - 10%) by mass ratio.

[0040] Preferably, the molar ratio of amino acid ester to titanate in the highly efficient composite catalyst is 1:3 - 1:5. The metal acetate, as an active site promoter, can increase the esterification reaction rate by more than 40%.

[0041] Preferably, in the dual catalyst system, the main catalyst is a titanium-based catalyst (accounting for 70 - 80%), and the co-catalyst is a metal hydroxide (such as Mg(OH) 2 )). The synergistic effect of the two can shorten the polycondensation reaction time to 1.5 hours, and the number-average molecular weight of the product is increased to 8.0×10 4 g / mol.

[0042] Titanium-based catalysts show good performance in the synthesis of poly(butylene succinate). For example, under the conditions that the esterification reaction temperature is 150 °C and the acid-alcohol ratio is 1:1.2, when using a titanium-based catalyst with a dosage of 0.1% to 0.5% of the molar amount of butanediol, PBS with a number-average molar mass between 5.7×10^4 and 8.0×10^4 g / mol can be prepared; highly efficient composite catalysts usually consist of multiple components, such as amino acids or amino acid esters, titanates, silicates, and metal acetates, etc. These catalysts are used to prepare poly(butylene succinate) with an intrinsic viscosity ≥ 1.8 dL·g^-1, an L value (lightness value) ≥ 85, and an acid value ≤ 10 mol / t through esterification reaction, pre-polycondensation reaction, and final polycondensation reaction; the double catalyst system synthesizes PBS through bulk melt polycondensation reaction, and the effects of catalyst dosage, the molar ratio of co-catalyst to main catalyst on the relative molecular mass and reaction time are studied. Therefore, no matter which one of the titanium-based catalyst, highly efficient composite catalyst, and double catalyst system is selected, it is beneficial to prepare poly(butylene succinate).

[0043] Preferably, in step 2, the stirring and mixing temperature is 130 - 150 °C, and the pressure is reduced to -10 °C using a vacuum pump.

[0044] Preferably, in step 3, the esterification reaction temperature is 130 - 170 °C, the esterification reaction pressure is carried out under normal pressure or inert gas protection, and the esterification reaction time is 1 - 3 hours.

[0045] Preferably, in step 4, the polycondensation reaction temperature is 200 - 230 °C, the polycondensation reaction pressure is 10 - 100 Pa, and the polycondensation reaction time is 1 - 5 hours.

[0046] Preferably, the separation and purification in step 5 include the following steps:

[0047] Step 51, pretreatment: Remove the organic solvent by water bath heating (50 °C), then extract in ethanol for 2 hours, filter, and crystallize at -10 °C for 12 hours;

[0048] Step 52, washing: Wash 3 times with toluene (purity ≥ 99.5%) for 10 minutes each time to remove chloride ions and unreacted monomers;

[0049] Step 53, drying: Dry in a vacuum drying oven (temperature 60 °C, pressure -10 °C) for 4 hours.

[0050] Preferably, the organic solvent used in the washing in step 52 is toluene.

[0051] Through the synergistic optimization of solvents and catalysts, combined with efficient separation and purification technologies, the industrial production cost is reduced to 8,000 - 10,000 yuan per ton, which is more than 70% lower than the traditional process (33,000 yuan per ton) and significantly superior to the current mainstream products in the market (35,000 - 40,000 yuan per ton), demonstrating outstanding economic competitiveness. This cost advantage stems from: (1) n-hexane solvent increases the molecular weight and dispersity of the product, reducing post-treatment energy consumption; (2) the efficient composite catalyst increases the esterification rate by 40% and reduces the catalyst dosage by 30%; (3) the vacuum drying process shortens the purification cycle to 4 hours and increases the production efficiency by 60%.

[0052] Example

[0053] Step 1. Raw material preparation: succinic acid, butanediol, catalyst, solvent;

[0054] Using n-hexane as the solvent and an efficient composite catalyst (amino acid ester: titanate = 1:3), the product has Mw = 7.5×10 4 g / mol, PDI = 1.1, intrinsic viscosity 2.1 dL / g, and acid value 8 mol / t.

[0055] Step 2. Stirring and mixing: Place the raw materials in a mixer for mixing and stirring; the stirring and mixing temperature is 130 - 150°C, and use a vacuum pump to reduce the pressure to -10°C.

[0056] Step 3. Esterification reaction: Carry out an esterification reaction on succinic acid and butanediol; the esterification reaction temperature is 130 - 170°C, the esterification reaction pressure is carried out under normal pressure or inert gas protection, and the esterification reaction time is 1 - 3 hours.

[0057] Step 4. Polycondensation reaction: Carry out a polycondensation reaction on the mixture after the esterification reaction; the polycondensation reaction temperature is 200 - 230°C, the polycondensation reaction pressure is 10 - 100 Pa, and the polycondensation reaction time is 1 - 5 hours.

[0058] Step 5. Separation and purification: Separate the mixture after the polycondensation reaction, remove the impurities therein, and carry out purification work to obtain polybutylene succinate; it includes the following steps:

[0059] Step 51. Pretreatment: Remove the organic solvent by water bath heating (50°C), then extract in ethanol for 2 hours, filter, and crystallize at -10°C for 12 hours;

[0060] Step 52. Washing: Wash 3 times with toluene (purity ≥ 99.5%) for 10 minutes each time to remove chloride ions and unreacted monomers;

[0061] Step 53. Drying: Dry in a vacuum drying oven (temperature 60°C, pressure -10°C) for 4 hours.

[0062] Comparative Example 1

[0063] Using tetrahydrofuran as the solvent and the dosage of the titanium-based catalyst being 0.3%, the product Mw = 5.2×10 4 g / mol, PDI = 1.5.

[0064] Comparative Example 2

[0065] Using toluene as the solvent and the highly efficient composite catalyst (amino acid ester: titanate = 1:4), the product Mw = 6.8×10 4 g / mol, PDI = 1.3.

[0066] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for synthesizing high value-added bio-based polybutylene succinate (PBS), characterized in that: The steps include: Step 1, raw material preparation: succinic acid, butanediol, catalyst, solvent; Step 2, stirring and mixing: placing the raw materials in a mixer for mixing and stirring; Step 3, esterification reaction: esterification reaction of succinic acid and butanediol; Step 4, polycondensation reaction: performing polycondensation reaction on the mixture after the esterification reaction; Step 5, separation and purification: separating the mixture after the polycondensation reaction, removing impurities therein, and purifying it to obtain polybutylene succinate.

2. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: The solvent in step 1 is selected from one of acetonitrile, tetrahydrofuran, toluene and n-hexane.

3. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: The catalyst in step 1 is selected from one of a titanium-based catalyst, a high-efficiency composite catalyst, and a dual catalyst system, wherein the high-efficiency composite catalyst is composed of amino acid ester (20-30%), titanate (40-50%), silicate (15-25%) and metal acetate (5-10%) in a mass ratio.

4. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 3, characterized in that: The molar ratio of amino acid ester to titanate in the high-efficiency composite catalyst is 1:3-1:5, and metal acetate is used as an active site promoter to increase the esterification reaction rate by more than 40%.

5. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 3, characterized in that: In the dual catalyst system, the main catalyst is a titanium catalyst (accounting for 70-80%), and the co-catalyst is a metal hydroxide (such as Mg(OH)2). The synergistic effect of the two can shorten the polycondensation reaction time to 1.5 hours and increase the number average molecular weight of the product to 8.0×10 4 g / mol.

6. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: The stirring and mixing temperature in step 2 is 130-150°C, and the pressure is reduced to -10℃。 7. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: In step 3, the esterification reaction temperature is 130-170° C., the esterification reaction pressure is carried out under normal pressure or inert gas protection, and the esterification reaction time is 1-3 hours.

8. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: In step 4, the polycondensation reaction temperature is 200-230° C., the polycondensation reaction pressure is 10-100 Pa, and the polycondensation reaction time is 1-5 hours.

9. A method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 1, characterized in that: The separation and purification in step 5 comprises the following steps: Step 51, pretreatment: removing the organic solvent by heating in a water bath (50°C), then leaching in ethanol for 2 hours, filtering and crystallizing at -10°C for 12 hours; Step 52, washing: washing with toluene (purity ≥ 99.5%) for 3 times, 10 minutes each time, to remove chloride ions and unreacted monomers; Step 53, drying: drying in a vacuum drying oven (temperature 60°C, pressure -10°C) for 4 hours.

10. The method for synthesizing a high value-added bio-based polybutylene succinate (PBS) according to claim 9, characterized in that: The organic solvent used in the washing in step 52 is toluene.

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