Method for continuously manufacturing bio-based polycarbonate polyol for high-performance polyurethane elastomer

Abstract

The invention discloses a continuous preparation method of a high-performance polyurethane elastomer based on a continuous flow technology, and belongs to the technical field of organic synthesis. The method comprises the following steps: in a continuous flow reactor, performing synthesis and polycondensation in a catalytic manner to synthesize a polyurethane prepolymer. Compared with an existing polyurethane elastomer manufacturing process, the method has the obvious advantages that the manufacturing process is efficient and stable, the difference between batches is small, byproducts do not need to be removed, the production cost is low, and good economic benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of polymer synthesis and polycondensation, and particularly relates to a technology for preparing polycarbonate polyols from bio-based raw materials in a continuous flow reaction system and further preparing high-performance polyurethane elastomers. Background Art

[0002] Polyurethane elastomers are high molecular compounds formed by the reaction of polyether or polyester polyols with polyisocyanates (such as HMDI, MDI). With their excellent properties, such as high elasticity, wear resistance, chemical corrosion resistance, etc., they are widely used in many fields. The quality of polycarbonate plays a decisive role in the performance of polyurethane. Traditional polycarbonate polyols are mostly synthesized from petrochemical raw materials. With the in-depth concept of sustainable development, finding environmentally friendly and renewable bio-based raw materials to prepare polycarbonate polyols and selecting high-quality polycarbonates from them for synthesizing polyurethane has become a research hotspot.

[0003] Currently, the catalytic polycondensation method is a common method for preparing polycarbonate polyols. In this method, polyol monomers and organic carbonates undergo a polycondensation reaction under the action of a catalytic system. The carbonate groups and aliphatic / alicyclic structural units in the product molecular chain are alternately distributed. The polyurethane elastomers produced in this way have good weather resistance [M.M M, et al. Thermo-environmental performance of polycarbonate materials as a glazing substitute in hot climates. Advances in Building Energy Research, (2024)], thermal stability, chemical stability, light aging resistance, and thermo-oxidative stability [Wongsamut C, et al. Structural and Dynamic Properties of Flame-Retardant Phosphorylated-Polycarbonate / Polycarbonate Blends. International Journal of Molecular Sciences, (2025): 3241-3241.], making them have important applications in microelectronics packaging, construction industry, medical equipment, and special coatings, etc.

[0004] However, there are many problems in the synthesis of traditional polyurethane elastomers. On the one hand, traditional synthesis is mostly carried out in a batch reactor. The batch reactor is large in volume, with poor mixing effect and low mass transfer efficiency, resulting in uneven product distribution and poor repeatability between batches, seriously restricting the industrial production scale and product quality stability. On the other hand, existing synthesis technologies mostly rely on petrochemical raw materials, which not only face the problem of resource depletion, but also require complex post-treatment for phenol residues; the use of petroleum-based monomers leads to high carbon emission intensity, increasing production costs and environmental burden. Continuous flow technology has made certain progress in the research of polyurethane elastomer synthesis, and among them, microfluidic reactors also show advantages such as high mass transfer efficiency and precise temperature control [Victoria R, et al. A disposable, continuous-flow polymerase chain reaction device: design, fabrication and evaluation.. Biomedical microdevices, (2016)], but there are still technical bottlenecks in the design and large-scale application of microfluidic reactors, such as small reactor throughput, short catalyst life, and poor adaptability to bio-based raw materials, which cannot achieve industrial production. At the same time, the application research of bio-based raw materials in continuous flow reaction systems is not deep enough. How to convert bio-based raw materials into high-quality polycarbonate polyols and meet the requirements of industrial production of high-performance polyurethane elastomers is an important research direction at present. Summary of the Invention

[0005] The present invention aims to overcome the deficiencies of the prior art. The object of the present invention is to provide a non-reversible and reproducible high-efficiency polycondensation method carried out in a continuous flow and a preparation method of high-performance polyurethane elastomers. Based on bio-based raw materials and combined with continuous flow technology, this method realizes the efficient, stable and green synthesis of polyurethane elastomers. The obtained products have excellent properties, meet the application requirements of high-performance polyurethane elastomers in the fields of microelectronics, construction, medical treatment, etc., while reducing production costs and environmental impact.

[0006] The present invention first proposes to use a continuous flow reactor to achieve large-scale preparation of polyurethane elastomers in a pipeline based on non-reversible reactions. The purity of the reaction by-product phenol is relatively high, and no column chromatography is required.

[0007] Based on the need not for multi-step purification of polycarbonate polyols, the present invention adopts a synthetic route of "polycondensation → transesterification" to realize the continuous synthesis of polyurethane elastomers in a microfluidic reactor. The conversion rate and yield of the reaction are high.

[0008] The technical solutions to achieve the above object are as follows:

[0009] A method for preparing a high-performance polyurethane elastomer, the steps of which are:

[0010] (1) Synthesis of polycarbonate polyol: A diol substrate and diphenyl carbonate are polycondensed in the presence of a catalyst to form a polycarbonate polyol.

[0011] (2) Synthesis of high-performance polyurethane elastomer: The polycarbonate polyol and isocyanate are polycondensed in the presence of a catalyst to form a high-performance polyurethane elastomer; the molecular formula of the high-performance polyurethane elastomer is shown as formula (I):

[0012]

[0013] R is a functional group, and the polycarbonate polyol containing R is selected from the following structures:

[0014]

[0015] The carbonate used for preparing the polycarbonate compound is: diphenyl carbonate.

[0016] The catalyst used for preparing the polycarbonate polyol is: methanesulfonic acid.

[0017] The isocyanate used for preparing the high-performance polyurethane elastomer compound is: 4,4'-methylene-bis(cyclohexyl isocyanate).

[0018] The specific method for polycondensing to prepare the polycarbonate polyol is: Under heating, methanesulfonic acid, diphenyl carbonate and diol are mixed evenly, and then put into a continuous flow reactor. After reacting fully for 1-8 h, the polycarbonate polyol is obtained.

[0019] The specific method for polycondensing to prepare the high-performance polyurethane elastomer is: Under heating, the obtained polycarbonate polyol, without purification, and 4,4'-methylene-bis(cyclohexyl isocyanate) are respectively put into a continuous flow reactor. After reacting fully for 2-10 hours, the high-performance polyurethane elastomer is obtained.

[0020] Beneficial effects

[0021] Adopting the technical solution of the present invention can at least achieve one of the following beneficial effects:

[0022] (1) The bio-based polycarbonate polyol prepared by the present invention, due to the introduction of bio-based raw materials, further improves the biocompatibility and sustainability of the material while maintaining the excellent properties of traditional polycarbonate polyols. When used to prepare high-performance polyurethane elastomers, it can significantly improve their comprehensive performance. For example, when applied in the medical field, the improvement of biocompatibility can reduce the body's rejection reaction; in the construction field, good weather resistance and chemical stability can extend the service life of the material.

[0023] (2) By-products phenol does not need to be removed during the whole synthesis process, reducing the environmental pollution caused by organic solvents. Moreover, the by-product phenol can be recycled and reused, further improving the resource utilization rate.

[0024] (3) The use of a continuous flow reactor gives the reaction system a large specific surface area, enabling rapid heat dissipation or heating, precisely controlling the reaction temperature, ensuring the stability of reaction conditions, and thus obtaining products with more uniform quality. At the same time, the continuous flow production method effectively reduces the differences between batches, improves production efficiency, and the reactor has a small volume and low potential hazards, making the production process safer and more reliable.

[0025] (4) Bio-based diols, diphenyl carbonate, methanesulfonic acid, and isocyanates are widely sourced and easily obtainable. Moreover, the reaction process does not require complex solvent recovery and treatment steps, reducing production costs. The reuse of the by-product phenol further improves economic efficiency, making the present invention more competitive in industrial production. Description of the Drawings

[0026] The embodiments of the present invention will be described in detail in conjunction with the accompanying drawings, where

[0027] Figure 1 : 1H NMR spectrum of the polyurethane prepolymer in Example 1

[0028] Figures 2 to 5 : Respectively, 1H NMR spectra of the polyurethane prepolymers in Examples 2 to 5 in sequence Detailed Embodiments

[0029] The present invention can be further illustrated by the following examples, which are for illustration purposes and not intended to limit the present invention. Any ordinary technician in the art can understand that these examples do not limit the present invention in any way and can make appropriate modifications and data transformations without departing from the essence and scope of the present invention.

[0030] The nuclear magnetic resonance hydrogen spectra involved in the examples were measured using a Bruker Ascend TM-400 nuclear magnetic resonance hydrogen spectrometer from Bruker Corporation, and the deuterated reagent used was deuterated chloroform (CDCl3).

[0031] The raw materials used in the following examples were all purchased from AlfaAesar.

[0032] The polycarbonate polyol used in the examples has the following structure:

[0033]

[0034] Example 1:

[0035] Add methanesulfonic acid (0.49 g, 5.1 mmol, 0.03 equiv), 1,6 - hexanediol (20 g, 0.17 mol, 1.0 equiv), and diphenyl carbonate (32.6 g, 0.15 mol, 0.9 equiv) into the reaction flask, and place it in a continuous - flow pipeline at 160 °C for reaction for 3 hours. The obtained product is an orange - red clear liquid. Transfer the obtained product and isocyanate (80.7 g, 0.48 mol, 2.9 equiv) into two syringes, fix them on the syringe pump, and then put them into a micro - flow field reactor at 50 °C for reaction for 4 h. The obtained product is a reddish - brown clear liquid. Coat it on the film with a film coater, put it into an oven at 80 °C for drying for 24 h, take out the dried film and conduct peel strength test. The hydrogen spectrum of the product is as shown in Figure 1 shown, (1H NMR, 400 Hz, CDCl3). The spectral data are: 1 H NMR (400 MHz, Chloroform - d) δ7.43 - 7.30 (m, 1H), 7.23 - 7.09 (m, 1H), 4.12 (t, J = 6.7 Hz, 9H), 4.03 (s, 2H), 3.39 (t, J = 6.7 Hz, 1H), 1.99 (d, J = 11.9 Hz, 1H), 1.67 (q, J = 6.8 Hz, 8H), 1.63 (s, 9H), 1.56 (q, J = 7.0, 6.4 Hz, 1H), 1.42 (tq, J = 8.3, 4.6, 4.2 Hz, 13H), 1.26 (d, J = 4.7 Hz, 1H), 1.11 (h, J = 7.7 Hz, 1H).

[0036] Example 2:

[0037] Add methanesulfonic acid (0.44 g, 4.6 mmol, 0.03 equiv), 1,7 - heptanediol (20 g, 0.15 mol, 1.0 equiv), and diphenyl carbonate (29.2 g, 0.14 mol, 0.9 equiv) into the reaction flask. Place it in a continuous - flow pipeline at 160 °C for reaction for 3 hours. The obtained product is an orange - red clear liquid. Transfer the obtained liquid and isocyanate (75.7 g, 0.45 mol, 2.9 equi v ) into two syringes, fix them on the syringe pump, and then put them into a micro - flow field reactor at 50 °C for reaction for 4 h. The obtained product is a reddish - brown clear liquid. Coat it on the film with a film coater, put it into an oven at 80 °C for drying for 24 h, take out the dried film and conduct peel strength test. The hydrogen spectrum of the product is as shown in Figure 2 shown, (1H NMR, 400 Hz, CDCl3). The spectral data are: 11H NMR (400 MHz, Chloroform-d) δ 7.43 - 7.30 (m, 1H), 7.23 - 7.08 (m, 1H), 4.11 (t, J = 6.7 Hz, 6H), 4.03 (dt, J = 11.1, 5.1 Hz, 1H), 3.82 - 3.74 (m, 0H), 3.38 (t, J = 6.7 Hz, 1H), 1.99 (d, J = 11.6 Hz, 1H), 1.81 - 1.72 (m, 1H), 1.67 (t, J = 7.1 Hz, 8H), 1.61 - 1.55 (m, 3H), 1.55 (d, J = 6.9 Hz, 1H), 1.49 - 1.32 (m, 13H), 1.22 - 1.05 (m, 1H), 1.00 (s, 1H).

[0038] Example 3:

[0039] Add methanesulfonic acid (0.39 g, 4.1 mmol, 0.03 equiv), 1,8 - octanediol (20 g, 0.14 mol, 1.0 equiv), and diphenyl carbonate (26.4 g, 0.12 mol, 0.9 equiv) to the reaction flask. React in a continuous - flow pipeline at 160 °C for 3 hours. The resulting product is an orange - red clear liquid. Transfer the obtained liquid and isocyanate (65.6 g, 0.39 mol, 2.9 equi v ) to two syringes, fix them to the syringe pump, and then put them into a micro - flow field reactor at 50 °C for reaction for 4 h. The resulting product is a reddish - brown clear liquid. Coat it on a film with a film coater, put it into an oven at 80 °C to dry for 24 h, and take out the dried film for peel strength testing. The 1H NMR spectrum of the product is as Figure 3 shown, (1H nuclear magnetic resonance spectrum, 400 Hz, CDCl3). The spectral data are: 1 1H NMR (400 MHz, Chloroform-d) δ 7.41 - 7.30 (m, 1H), 7.23 - 7.09 (m, 1H), 4.11 (t, J = 6.7 Hz, 7H), 4.03 (d, J = 7.0 Hz, 2H), 3.38 (t, J = 6.7 Hz, 1H), 1.99 (d, J = 11.8 Hz, 1H), 1.83 - 1.73 (m, 1H), 1.72 (d, J = 13.6 Hz, 1H), 1.66 (t, J = 7.2 Hz, 8H), 1.57 (s, 1H), 1.48 - 1.03 (m, 22H), 1.03 - 0.93 (m, 1H).

[0040] Example 4:

[0041] Add methanesulfonic acid (0.36 g, 3.7 mmol, 0.03 equiv), 1,9-nonanediol (20 g, 0.13 mol, 1.0 equiv), and diphenyl carbonate (24.0 g, 0.11 mol, 0.9 equiv) to the reaction flask. React in a continuous flow pipe at 160 °C for 3 hours. The resulting product is an orange-red clear liquid. Transfer the obtained liquid and isocyanate (58.9 g, 0.35 mol, 2.9 equiv) to two syringes, fix them to the syringe pump, and then put them into a microfluidic reactor at 50 °C for reaction for 4 h. The resulting product is a reddish-brown clear liquid. Coat it on a film with a film coater and dry it in an oven at 80 °C for 24 h. Take out the dried film and conduct a peel strength test. The hydrogen spectrum of the product is as shown in Figure 4 shown, (1H NMR, 400 Hz, CDCl3). The spectral data are: 1 H NMR (400 MHz, Chloroform-d) δ4.11 (t, J = 6.7 Hz, 10H), 4.02 (s, 2H), 3.38 (t, J = 6.7 Hz, 1H), 1.67 (q, J = 7.0 Hz, 11H), 1.56 (dd, J = 14.2, 7.5 Hz, 6H), 1.37 (d, J = 8.0 Hz, 6H), 1.30 (q, J = 4.3 Hz, 28H), 1.16 - 1.03 (m, 2H).

[0042] Example 5:

[0043] Add methanesulfonic acid (0.33 g, 3.4 mmol, 0.03 equiv), 1,10-decanediol (20 g, 0.11 mol, 1.0 equiv), and diphenyl carbonate (22.1 g, 0.10 mol, 0.9 equiv) to the reaction flask. React in a continuous flow pipe at 160 °C for 3 hours. The resulting product is an orange-red clear liquid. Transfer the obtained liquid and isocyanate (53.8 g, 0.32 mol, 2.9 equiv) to two syringes, fix them to the syringe pump, and then put them into a microfluidic reactor at 50 °C for reaction for 4 h. The resulting product is a reddish-brown clear liquid. Coat it on a film with a film coater and dry it in an oven at 80 °C for 24 h. Take out the dried film and conduct a peel strength test. The hydrogen spectrum of the product is as shown in Figure 1 shown, (1H NMR, 400 Hz, CDCl3). The spectral data are: 11H NMR (400 MHz, Chloroform-d) δ 7.35 (t, J = 7.8 Hz, 1H), 7.16 - 7.09 (m, 1H), 4.11 (t, J = 6.7 Hz, 9H), 4.02 (s, 1H), 3.77 (s, 1H), 3.38 (t, J = 6.8 Hz, 2H), 1.99 (d, J = 11.9 Hz, 1H), 1.65 (q, J = 7.0 Hz, 10H), 1.56 (dd, J = 14.4, 7.6 Hz, 6H), 1.37 (s, 2H), 1.33 (dd, J = 11.2, 5.5 Hz, 15H), 1.29 (d, J = 5.1 Hz, 16H), 1.18 - 1.06 (m, 1H), 1.00 (s, 1H).

[0044] The peel force test measured data such as the tensile strength, maximum displacement, and maximum force regarding the properties of the polyurethane elastomer. The results are shown in Table 1.

[0045] Table 1 Determination of the Tensile Properties of the Polyurethane Elastomer

[0046]

[0047]

[0048] It can be seen from the above results that the polyurethane elastomer catalysts provided in Examples 1 - 5 have good catalytic activity, and under certain reaction conditions, the polymerization reaction of isocyanate and polycarbonate diol is completed relatively quickly; in Example 3, the polyurethane elastomer prepared has excellent physical properties and better viscosity.

Claims

1. A preparation method of a high-performance polyurethane elastomer, characterized in that: It includes the following steps: (1) Synthesis of polycarbonate polyol: A diol substrate and diphenyl carbonate are polycondensed under the action of a catalyst to produce polycarbonate polyol; (2) Synthesis of high-performance polyurethane elastomer: Polycarbonate polyol and isocyanate are polycondensed under the action of a catalyst to produce high-performance polyurethane elastomer; The molecular formula of the high-performance polyurethane elastomer is shown in Formula (I): R is a functional group, and the polycarbonate polyol containing R is selected from the following structures:

2. The preparation method according to claim 1, characterized in that: The catalyst in step (1) is methanesulfonic acid.

3. The preparation method according to claim 1, characterized in that: The carbonate used for polycondensation in step (1) is diphenyl carbonate.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the diol, carbonate and catalyst in step (1) is 1:0.5:0.003 to 1:2.99:0.

3.

5. The preparation method according to claim 1, characterized in that: Step (1) is carried out in a continuous flow reactor, reacting at 50-200 °C for 1-8 hours.

6. The preparation method according to claim 1, characterized in that: The isocyanate used for the polycondensation reaction in step (2) is 4,4′-methylene-bis(cyclohexyl isocyanate).

7. The preparation method according to claim 1, characterized in that: The molar ratio of the polycarbonate polyol and isocyanate in step (2) is 1:0.9: to 1:2.

99.

8. The preparation method according to claim 1, wherein: Step (2) is carried out in a continuous flow reactor, reacting at 30-90 °C for 2-10 hours.

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