TWI797953B - A non-phosgene process for preparing polyurethanes and their intermediates - Google Patents

Abstract

A non-phosgene process for preparing polyurethanes comprises following steps: Digest polycarbonates by amino-alcohols and follow by pyrolysis to obtain an intermediate comprises a cyclic urethane, and then prepare the polyurethanes via a ring-opening polymerization of the cyclic urethanes.

Description

A kind of non-phosgene method polyurethane production process and its intermediate product

The invention provides a non-phosgene method polyurethane production process and intermediate products thereof. Specifically, the aforesaid non-phosgene method polyurethane production process includes the following steps: after polycarbonate and monoalcohol amine compound are subjected to digestion and cracking reactions, an intermediate product comprising cyclic carbamate is obtained, and then the cyclic carbamate is The acid ester is then subjected to ring-opening polymerization to obtain polyurethane.

In the technical field of polyurethane (PU), the traditional preparation method needs to use isocyanate as the starting material, but isocyanate is mainly produced by the highly toxic gas carbonyl chloride (COCl ₂ , phosgene), which is a highly toxic and corrosive gaseous substances. Therefore, the conventional phosgene-based polyurethane manufacturing process requires a rather complex safety design, thereby reducing the risk of industrial safety accidents and the resulting hazards.

Furthermore. With today's environmental pollution, global warming intensifying, and social environmental awareness rising, how to solve plastic waste by recycling, sorting and reusing waste in daily life, such as discarded polycarbonate, is actually a problem facing the industry today. big challenge.

To sum up, how to design a novel process technology so that waste polymer materials or plastics can be recycled to obtain another polymer material is still a major topic that the industry needs to invest in research and development, so as to achieve The purpose of circular economy and green chemistry.

In view of the above-mentioned previous technical background, in order to conform to the future development trend of the industry In order to achieve the purpose of circular economy and green chemistry, the present invention provides a non-phosgene polyurethane manufacturing process and its intermediate products. In particular, the non-phosgene polyurethane process uses polycarbonate as raw material to prepare polyurethane.

Specifically, the non-phosgene polyurethane production process includes the following steps: step 1, performing a digestion reaction on polycarbonate and a monoalcohol amine compound, thereby obtaining a first intermediate product; step 2, performing a cracking reaction on the above-mentioned first intermediate product , thereby obtaining a second intermediate product comprising a cyclic carbamate; and Step 3, subjecting the cyclic carbamate to ring-opening polymerization, thereby obtaining the polyurethane.

More specifically, the non-phosgene polyurethane production process is to subject the polycarbonate and the alcohol amine compound to an aminolysis digestion reaction to generate the first intermediate product, and then pyrolyze the first intermediate product to obtain the cyclic amine-containing The second intermediate product of carbamate, obtain high-purity cyclic carbamate through separation and purification steps, and use the high-purity cyclic carbamate as a monomer to carry out cationic ring-opening polymerization reaction, by This gives the polyurethanes described. Specifically, the polyurethane is an aliphatic linear polyurethane.

To sum up, the non-phosgene polyurethane manufacturing process described in the present invention is also a non-isocyanate polyurethane manufacturing process. Compared with the known phosgene method or isocyanate method polyurethane process, it obviously has the advantages of safe and harmless raw materials and environmental friendliness, and has the process technology characteristics of high atomic economic benefits, and can achieve the goals of green chemistry and circular economy.

In particular, the non-phosgene polyurethane process can be further applied to recycle waste polycarbonate, without adding any catalyst, the waste polycarbonate can be digested and cracked to form cyclic carbamate , and its yield is at least 40%, and the cyclic urethane is then subjected to ring-opening polymerization to obtain the aliphatic linear polyurethane, which endows the waste poly The new use and value of carbonate achieves the economic purpose of waste recycling and high value.

〔Fig. 1〕 is the non-phosgene process polyurethane process path diagram of the present invention.

[Fig. 2] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the cleavage product pDPC-2C of the present invention.

[Fig. 3] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the cleavage product pDPC-3C of the present invention.

[Fig. 4] is the ¹ H-NMR spectrum analysis chart of the cleavage product pDPC-4C of the present invention.

[Fig. 5] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the cleavage product pDPC-5C of the present invention.

[Fig. 6] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the cleavage product pDPC-6C of the present invention.

[Fig. 7] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the five-membered cyclic carbamate of the present invention.

[Fig. 8] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the six-membered cyclic carbamate of the present invention.

[Figure 9] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis chart of the seven-membered cyclic carbamate of the present invention

[Fig. 10] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis diagram of the polyurethane prepared by the six-membered cyclic carbamate of the present invention.

[Fig. 11] is the ¹ H-NMR nuclear magnetic resonance spectrum analysis diagram of polyurethane prepared from seven-membered cyclic carbamate of the present invention.

[Fig. 12] is the thermogravimetric analysis diagram of polyurethane prepared from six-membered and seven-membered cyclic carbamates of the present invention.

[Figure 13] is the DSC analysis chart of the polyurethane prepared from six-membered cyclic urethane according to the present invention.

[Figure 14] is the DSC analysis chart of the polyurethane prepared from the seven-membered cyclic urethane of the present invention.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. In order to provide a thorough understanding of the present invention, detailed steps and components thereof will be set forth in the following description. Obviously, the practice of the invention is not limited to specific details familiar to those skilled in the art. On the other hand, well-known components or steps are not described in detail in order to avoid unnecessarily limiting the invention. The preferred embodiments of the present invention will be described in detail as follows, but in addition to these detailed descriptions, the present invention can also be widely implemented in other embodiments, and the scope of the present invention is not limited, which is subject to the scope of the patents that follow .

According to the aforementioned content of the invention, the first embodiment of the present invention discloses a non-phosgene polyurethane production process, which uses polycarbonate as raw material to prepare polyurethane, and the above-mentioned non-phosgene polyurethane production process is also a non-phosgene polyurethane production process. Isocyanate-based polyurethane process. Accordingly, compared with the conventional phosgene or isocyanate polyurethane production process, the non-phosgene polyurethane production process of the present invention obviously has the advantages of safe and harmless raw materials and environmental friendliness, as well as a process technology with high atomic economic benefits Features, can achieve the goal of green chemistry and circular economy.

In particular, the non-phosgene polyurethane process can be further applied to the recovery of waste polycarbonate, without adding any catalyst, the waste polycarbonate can be digested and cracked to form cyclic carbamate , and its yield is at least 40%, the ring-opening polymerization of the cyclic urethane to obtain aliphatic linear polyurethane, which endows the waste polycarbonate with new uses and values, and achieves waste recycling and high-value economic purpose.

In a specific embodiment, the above-mentioned non-phosgene polyurethane manufacturing process includes the following steps step.

Step 1. Digesting the polycarbonate and the monoalcohol amine compound to obtain a first intermediate product.

Step 2, subjecting the above-mentioned first intermediate product to a cleavage reaction, thereby obtaining a second intermediate product comprising a cyclic carbamate.

Step 3, subjecting the cyclic carbamate to ring-opening polymerization, thereby obtaining the polyurethane.

In a specific embodiment, the alcoholamine compound is selected from one or a combination of the following groups: ethanolamine, 3-amino-1-propanol and 4-amino-1-butanol.

In a specific embodiment, the composition of the first intermediate product includes bisphenol A (BPA), diphenylene monocarbamate and diphenylene biscarbamate.

In a specific embodiment, the temperature range of the cracking reaction is 180-250°C. Preferably, the temperature range is 180-220°C.

In a specific embodiment, the cyclic carbamate is a five-membered cyclic carbamate, a six-membered cyclic carbamate or a seven-membered cyclic carbamate. It has a general structural formula as shown in formula (1), wherein n is an integer from 2 to 4.

In a specific embodiment, the ring-opening polymerization reaction is a cationic ring-opening polymerization reaction answer.

In a specific embodiment, the initiator of the cationic ring-opening polymerization comprises methyl trifluoromethanesulfonate, ethyl trifluoromethylsulfonate or a combination thereof.

In one embodiment, the non-phosgene polyurethane production process further comprises a purification step of separating the cyclic carbamate from the second intermediate product.

In a specific embodiment, the purification step comprises vacuum distillation, column chromatography, precipitation, crystallization, sublimation or any combination thereof.

In a preferred embodiment, the purification step for isolating the five-membered cyclic carbamate is vacuum distillation.

In another preferred embodiment, the purification step for isolating the six-membered cyclic carbamate is column chromatography.

In another preferred embodiment, the purification steps for isolating the seven-membered cyclic carbamate are column chromatography and sublimation.

In a specific embodiment, the polyurethane is a linear polyurethane with an average molecular weight ranging from 5,000 to 25,000 Da.

The second embodiment of the present invention provides a recycling method of waste polycarbonate, which uses the non-phosgene polyurethane production process as described in the first embodiment to regenerate the waste polycarbonate into a linear polyurethane.

In a specific embodiment, the average molecular weight of the linear polyurethane is in the range of 5,000-20,000 Da.

In a representative embodiment, please refer to the steps shown in Figure 1. The non-phosgene polyurethane production process of the present invention includes: Step 1. Digestion of polycarbonate by using alcohol amines with different carbon chain lengths Aminolysis and obtain the first intermediate product, its composition comprises bisphenol A (BPA), diphenylene monocarbamate (DP-monocarbamates) and diphenylene dicarbamate (DP-biscarbamates); Step 2. The first intermediate product is cracked at high temperature, and the diphenylene monocarbamate (DP-monocarbamates) and diphenylene biscarbamate (DP-biscarbamates) are generated by breaking bonds at high temperature The isocyanate reacts with the hydroxyl group in the structure to make it reorganize into cyclic carbamate and BPA, which is the second intermediate product; step 3, purifying the cyclic carbamate in different ways; and step 4 1. Using the purified cyclic carbamate as a monomer, the polyurethane is prepared by cationic ring-opening polymerization.

The technical features of the present invention are described below with examples and serve as proof that the present invention has innovative technical effects.

Example 1: General procedure for alcohol amine digestion of polycarbonate as a first intermediate and analysis of the first intermediate

Digest polycarbonate with ethanolamine (2C) as the first intermediate product: install a 250ml double-neck round bottom flask with a nitrogen atmosphere and a feeding tube, add polycarbonate (EW=254.28, 3g, 11.8mmol), and then add benzene Dissolve 30ml of methyl ether in a preheated 90°C oil pan with a magnet. After the polycarbonate is completely dissolved, lower the temperature to 75°C, slowly add ethanolamine (MW=61.08, 0.735g, 12mmol) dissolved in 10ml of anisole through the feed tube, and monitor the polycarbonate with FT-IR during the process When the characteristic absorption peak of C=O stretching at 1773cm ^-1 disappears completely, it is judged that the digestion is complete. The solid is collected by filtration, dried and analyzed by ¹ H-NMR.

FT-IR (KBr): 1705 cm ^-1 ((NH)C=OO, oxazolidone).

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.52(s,6H), 6.62-6.67(m,4H), 6.95-7.01(m,4H), 8.91(s,2H). δ(ppm)=3.41-3.47(m,2H), 4.24-4.32(m,2H),7.47(s,1H).

Digesting polycarbonate with 3-amino-1-propanol (3C) is the first intermediate product: the device has a 250ml double-necked round-bottomed flask with a nitrogen environment and a feed tube, and polycarbonate (EW=254.28, 3g, 11.8 mmol) was added, followed by 90ml of anisole, and dissolved in a preheated 90°C oil pan with magnetic stirring. After the polycarbonate is completely dissolved, lower the temperature to 75°C, and slowly add 3-amino-1-propanol (MW=75.11, 0.9039g, 12mmol) dissolved in 10ml of anisole through the feeding tube, the process is described as FT -IR monitoring polycarbonate C=O stretching when the characteristic absorption peak at 1773cm ^-1 disappears completely, it is judged that the digestion is complete. After the solvent was distilled off under reduced pressure, it was analyzed by ¹ H-NMR.

FT-IR (KBr): 1715 cm ^-1 ((NH)C=OO, urethane).

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.51-1.65(m,2H),1.51-1.65(m,6H),3.00-3.11(m,2H),3.36-3.48(m , 2H), 4.45(t, 1H), 6.57-7.33(m, 8H), 7.64(t, 1H), 9.12(s, 2H). δ(ppm)=1.74-1.83(m,2H),3.11-3.18(m,2H),4.13(t,2H),7.14(s,1H).

Digesting polycarbonate with 4-amino-1-butanol (4C) is the first intermediate product: the device has a 250ml double-neck round bottom flask with a nitrogen environment and a feed tube, and polycarbonate (EW=254.28, 3g, 11.8 mmol) was added, followed by 90ml of anisole, and dissolved in a preheated 90°C oil pan with magnetic stirring. After the polycarbonate is completely dissolved, lower the temperature to 75°C, and slowly add 4-amino-1-butanol (MW=89.14, 1.0727g, 12mmol) dissolved in 10ml of anisole through the feeding tube. -IR monitoring polycarbonate C=O stretching when the characteristic absorption peak at 1773cm ^-1 disappears completely, it is judged that the digestion is complete. After the solvent was distilled off under reduced pressure, it was analyzed by ¹ H-NMR.

FT-IR (KBr): 1715 cm ^-1 ((NH)C=OO, urethane).

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.33-1.41(m, 2H), 1.41-1.49(m, 4H), 1.50-1.65(m, 6H), 3.00-3.09(m ,2H), 3.36-3.44(m,2H), 4.35-4.44(m,1H), 6.59-7.31(m,8H), 7.65-7.76(m,1H), 9.14(s,2H). δ(ppm)=1.52-1.62(m,2H),1.70-1.80(m,2H),2.91-2,98(m,2H),3.97(t,2H),7.13(s,1H).

Digesting polycarbonate with 5-amino-1-pentanol (5C) is the first intermediate product: the device has a 250ml double-necked round-bottomed flask with a nitrogen environment and a feed tube, and polycarbonate (EW=254.28, 3g, 11.8 mmol) was added, followed by 90ml of anisole, and dissolved in a preheated 90°C oil pan with magnetic stirring. After the polycarbonate is completely dissolved, lower the temperature to 75°C, and slowly add 4-amino-1-butanol (MW=103.16, 1.2424g, 12mmol) dissolved in 10ml anisole through the feeding tube, the process is described as FT -IR monitoring polycarbonate C=O stretching when the characteristic absorption peak at 1773cm ^-1 disappears completely, it is judged that the digestion is complete. After the solvent was distilled off under reduced pressure, it was analyzed by ¹ H-NMR.

FT-IR (KBr): 1715 cm ^-1 ((NH)C=OO, urethane).

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.20-1.36(m,2H),1.36-1.49(m,2H),1.49-1.66(m,6H),3.03(q,2H ), 3.39(q,2H), 4.35(t,1H), 6.59-7.26(m,8H), 7.66(q,1H), 9.13(s,2H).

Digesting polycarbonate with 6-amino-1-hexanol (6C) is the first intermediate product: the device has a 250ml double-neck round bottom flask with a nitrogen environment and a feed tube, and polycarbonate (EW=254.28, 3g, 11.8 mmol) was added, followed by 90ml of anisole, and dissolved in a preheated 90°C oil pan with magnetic stirring. After the polycarbonate is completely dissolved, lower the temperature to 75°C, and slowly add 4-amino-1-butanol (MW=117.19, 1.4103g, 12mmol) dissolved in 10ml of anisole through the feeding tube. -IR monitoring polycarbonate C=O stretching when the characteristic absorption peak at 1773cm ^-1 disappears completely, it is judged that the digestion is complete. After the solvent was distilled off under reduced pressure, it was analyzed by ¹ H-NMR.

FT-IR (KBr): 1715 cm ^-1 ((NH)C=OO, urethane).

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.17-1.35(m,2H),1.35-1.48(m,2H),1.50-1.66(m,2H),2.89-3.06(m ,2H), 3.03(q,2H), 3.37(q,2H), 4.35(t,1H), 6.60-7.32(m,8H), 7.68(q,1H), 9.16(s,2H).

The first intermediate product of this series is called DPC-X, and X represents the aminolysis monomer; where ethanolamine is 2C, 3-amino-1-propanol is 3C, 4-amino-1-butanol is 4C, 5-amino- 1-pentanol is 5C, 6-amino-1-hexanol is 6C.

Example 2: General procedure for cleaving the first intermediate to prepare a second intermediate comprising a cyclic carbamate and analysis of the second intermediate

Cracking of DPC-2C: DPC-2C is placed in a distillation device, and the cracking and distillation steps are carried out at a pressure of 1.5x10 ^-3 Torr and a temperature of 150°C-200°C. After the cracking and distillation are completed, the DPC-2C is collected and analyzed by ¹ H-NMR The ¹ H-NMR spectrum of the second intermediate product obtained by the cleavage is shown in FIG. 2 . Final calculated yield: 97.5 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.52(s,6H), 6.64(m,4H), 6.98(m,4H), 9.12(s,2H). δ(ppm)=3.41-3.47(m,2H), 4.24-4.32(m,2H),7.47(s,1H).

Cracking of DPC-3C: DPC-3C is placed in a distillation device, and the cracking and distillation steps are carried out at a pressure of 1.5x10 ^-3 Torr and a temperature of 150°C-210°C. After the cracking and distillation are completed, the DPC-3C is collected and analyzed by ¹ H-NMR The chemical composition analysis of the second intermediate product obtained by the cleavage was carried out, and the ¹ H-NMR spectrum is shown in FIG. 3 . Finally calculated yield: 93.2 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.52(s,6H), 6.61-6.69(m,2H), 6.94-7.03(m,4H), 9.13(s,2H). δ(ppm)=1.74-1.83(m,2H), 3.11-3.18(m,2H), 4.13(t,2H),7.14(s,1H).

Cracking of DPC-4C: DPC-4C is placed in a distillation device, and the cracking and distillation steps are carried out at a pressure of 1.5x10 ^-3 Torr and a temperature of 150°C-200°C. After the cracking and distillation are completed, the DPC-4C is collected and analyzed by ¹ H-NMR The chemical composition analysis of the second intermediate product obtained by the cleavage was carried out, and the ¹ H-NMR spectrum is shown in FIG. 4 . Final calculated yield: 76.4 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.52(s,6H), 6.57-6.71(m,4H), 6.91-7.05(d,4H), 9.15(s,2H). δ(ppm)=1.52-1.62(m,2H),1.70-1.80(m,2H),2.91-2.98(m,2H),3.96(t,2H),7.09-7.26(m,1H).

Cracking of DPC-5C: DPC-5C is placed in a distillation device, and the cracking and distillation steps are carried out at a pressure of 1.5x10 ³ Torr and a temperature of 150°C-220°C. After the cracking and distillation are completed, it is collected and carried out by ¹ H-NMR The ¹ H-NMR spectrum of the second intermediate product obtained from the cleavage was analyzed for its chemical composition, as shown in FIG. 5 . Final calculated yield: 67.3 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.33-1.53(m,4H),1.52-1.68(m,6H),3.10(q,2H),3.46(t,2H), 4.50 (s, 1H), 6.59-7.28 (m, 8H), 7.64 (q, 1H), 9.20 (s, 2H).

Cracking of DPC-6C: DPC-6C is placed in a distillation device, and the cracking and distillation steps are carried out at a pressure of 1.5x10 ^-3 Torr and a temperature of 150°C-220°C. After the cracking and distillation are completed, the DPC-6C is collected and analyzed by ¹ H-NMR The chemical composition analysis of the second intermediate product obtained by the cleavage was carried out, and the ¹ H-NMR spectrum is shown in FIG. 6 . Final calculated yield: 64.8 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.19-1.48(m,4H),1.47-1.61(m,6H),2.89-3.06(m,2H),3.84-4.00(m ,2H), 4.30-4.45(m,1H), 6.60-7.27(m,8H), 7.67(t,1H), 9.16(s,2H).

The second intermediate product of this series is called p-DPC-X, X represents the aminolysis monomer, in which ethanolamine is 2C, 3-amino-1-propanol is 3C, 4-amino-1-butanol is 4C, 5- Amino-1-pentanol is 5C, 6-amino-1-hexanol is 6C.

According to the experimental results of Example 2, the H NMR spectra of the second intermediate products p-DPC-2C to p-DPC-6C are shown in FIGS. 2 to 6 . From the analysis of Figure 2, Figure 3 and Figure 4, it is confirmed that the Phenolic monocarbamates and DP-biscarbamates obtained from the polycarbonate (PC) digestion step are converted into corresponding cyclic carbamates in a high proportion after pyrolysis and BPA, but the formation of the corresponding cyclic carbamate was not observed in Figure 5 and Figure 6. This result shows that at high temperature, Phenolic monocarbamates and DP-biscarbamates with short carbon chain length alcoholamines (n=2-4) have cyclization reaction; but the end is long carbon chain length alcoholamines (n=5 -6) Phenolic monocarbamates and DP-biscarbamates, no cyclization reaction occurred. Accordingly, it is confirmed that the cleavage reaction step of the present invention has specificity, and the ring-forming ratio of the cleavage reaction step is summarized in Table 1.

Example 3: General procedure for purification of the cyclic carbamate from the second intermediate product and analysis of the cyclic carbamate

Purification from p-DPC-2C to obtain five-membered cyclic carbamate: put pDPC-2C in the distillation apparatus again, carry out distillation at a pressure of 3x10 ^-2 Torr and a temperature of 130°C for 2 hours, collect after the distillation is completed , and the chemical composition was analyzed by ¹ H-NMR, and the ¹ H-NMR spectrum is shown in FIG. 7 . Five-membered cyclic carbamate yield: 91.9wt%, BPA yield: 99.0wt%.

¹ H-NMR (400 MHz, DMSO-d ₆ ): δ (ppm) = 3.41-3.47 (m, 2H), 4.24-4.32 (m, 2H), 7.47 (s, 1H).

Purification from p-DPC-3C to obtain six-membered cyclic carbamate: pDPC-3C was separated by column chromatography using ethyl acetate/hexane (1/1, v/v) as the initial eluting solvent , and then purified by using tetrahydrofuran as the eluting solvent, collected and dried, and analyzed by ¹ H-NMR. ^{The 1} H-NMR spectrum is shown in FIG. 8 . The yield of six-membered cyclic carbamate: 50.0wt%, the yield of BPA: 89.0wt%.

¹ H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.74-1.87 (m, 2H), 3.11-3.18 (m, 2H), 4.14 (t, 2H), 7.10 (s, 1H).

Purified from p-DPC-4C to obtain seven-membered cyclic carbamate; pDPC-4C was separated by column chromatography using ethyl acetate/hexane (2/1, v/v) as the initial eluting solvent , and then purified with ethyl acetate as the eluting solvent, collected and dried, then sublimed at 60°C and 1.5x10 ^-3 Torr, and analyzed with ¹ H-NMR after collecting the solid. ^{The 1} H-NMR spectrum is shown in the figure 9. Yield of seven-membered cyclic carbamate: 49.8wt%, BPA yield: 93.0wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.52(s,6H), 6.57-6.71(m,4H), 6.91-7.05(d,4H), 9.15(s,2H). δ(ppm)=1.52-1.62(m,2H),1.70-1.80(m,2H),2.91-2.98(m,2H),3.96(t,2H),7.09-7.26(m,1H).

The hydrogen nuclear magnetic resonance spectra of the above-mentioned cyclic carbamate after purification and separation are shown in FIGS. 7 to 9 . Accordingly, it is confirmed that the present invention successfully obtains the above-mentioned cyclic carbamate after digestion, aminolysis, pyrolysis reaction and separation and purification of polycarbonate. Cyclic amine group after purification step The yields of formate and BPA are summarized in Table 2.

Example 4. The general steps for preparing polyurethane from the above-mentioned cyclic carbamate and the analysis of the polyurethane

Preparation of polyurethane with six-membered cyclic carbamate: under nitrogen atmosphere, weigh 0.8g of six-membered cyclic carbamate, and draw 4.4ul (0.0066g) trifluoromethanesulfonate with an adjustable quantitative straw Put the methyl ester into a pressure bottle, and then put it into a molten state in a preheated oil pan at 100°C and stir it with a magnet for 2 days. Solid precipitation can be observed. After cooling down, dissolve the solid with 8ml DMAc and drop into 200ml of methanol , white solids were observed to precipitate, and the precipitated solids were collected by filtration and analyzed by ¹ H-NMR. Yield: 12.5 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.65(p,2H), 3.01(q,2H), 3.92(t,2H), 7.11(s,1H).

Preparation of polyurethane with seven-membered cyclic carbamate: under nitrogen environment, weigh 0.2 g of seven-membered cyclic carbamate, and draw 2.8ul (0.0041g) trifluoromethanesulfonate with an adjustable quantitative straw Put the methyl ester into a pressure bottle, then put it into a molten state in a preheated 67°C oil pan and stir it with a magnet for 12 hours. A white solid can be observed. After cooling down, wash the solid with 5ml DCM and collect it by filtration. Then, it was analyzed by ¹ H-NMR. Yield: 39.3 wt%.

¹ H-NMR (400MHz, DMSO-d ₆ ): δ(ppm)=1.32-1.57(m,4H), 2.95(q,2H), 3.90(t,2H), 7.06(t,1H).

The above-mentioned polyurethane prepared by cationic ring-opening polymerization is named PU (Y-ring), and Y represents that the cyclic urethane monomer used is a Y-membered ring. (If cationic ring-opening polymerization is carried out with six-membered cyclic urethane, it is called PU (6-ring), if it is polymerized with seven-membered cyclic urethane, it is called PU (7-ring) )).

Structure and Molecular Weight Analysis of Polyurethane Prepared from Six- and Seven-membered Cyclic Urethanes

According to the H-NMR spectrum shown in Figure 10 and Figure 11, ¹ H-NMR (400MHz, DMSO-d ₆ ) of PU (6-ring): δ (ppm) = 1.65 (p, 2H), 3.01 (q ,2H), 3.92(t,2H),7.11(s,1H)). ¹ H-NMR (400MHz, DMSO-d ₆ ) of PU (7-ring): δ (ppm) = 1.32-1.57 (m, 4H), 2.95 (q, 2H), 3.90 (t, 2H), 7.06 ( t,1H)), thus confirming that the present invention successfully prepared linear PU with six-membered and seven-membered cyclic carbamates by cationic ring-opening polymerization, and further passed the NMR of the CH ₃ structure in the carbamate group Molecular weights were calculated from the integral value of the resonance proton spectrum. The M _n calculated by the integral value of the above terminal group, PU(6-ring) is 17235, PU(7-ring) is 5667, both are close to the theoretical value (PU(6-ring) and PU(7-ring) are respectively 19998 and 8625).

Analysis of thermal properties of polyurethane prepared from six- and seven-membered cyclic carbamates

As shown in Figure 12, the thermal cracking temperature (decomposed temperature, T _d ) is defined as the 5% weight loss temperature, which is mainly affected by the heat resistance of each group in the structure. In order to avoid oxidation reaction, under the protection of 10ml/min nitrogen environment, the solvent and water vapor were removed at a constant temperature of 100°C for 10 minutes, and then the thermal stability of the material was analyzed by TGA at a heating rate of 10°C per minute. Weight loss relationship. The PU prepared by cationic ring-opening polymerization is measured by TGA. It can be observed that the T _d of PU (6-ring) is about 206°C, and the main weight loss temperature is about 273°C; the T _d of PU (7-ring) It is 242°C, and the main weight loss temperature is about 300°C. Comparing PU (6-ring) and PU (7-ring) shows that as the number of carbons between the carbamate functional groups of linear PU increases, its thermal stability also improves.

As shown in the DSC curve of Figure 13, the measurement condition of PU (6-ring) is to start from -50°C, raise the temperature to 200°C at a rate of 10°C/min, and then keep the temperature for 1 minute to eliminate the thermal history. The cooling rate of 10°C per minute is reduced to -50°C, maintained at -50°C for 1 minute, and then heated from -50°C to 200°C at a rate of 10°C per minute for observation. PU (6-ring) has good crystallinity. The melting point (T _m ) in the 1st run is 168°C. After the 2nd run is higher than the glass transition temperature, it can be observed that the recrystallization temperature (T _c ) is about 100.7°C. , with a melting point of 163.4°C.

As shown in Figure 14, the measurement condition of PU (7-ring) is to increase the temperature from -50°C, raise the temperature to 220°C at a rate of 10°C/min, then keep the temperature for 1 minute to eliminate the thermal history, and then increase the temperature at 10°C/min. The cooling rate of °C is reduced to -50 °C, maintained at -50 °C for 1 minute, and then heated from -50 °C to 220 °C at a rate of 10 °C per minute for observation. PU (7-ring) also has good crystallinity. The melting point in the 1st run was about 208°C, and a recrystallization peak appeared when the temperature was lowered. Two melting points were observed in the 2nd run, which were about 206°C. It was speculated that two crystal forms were formed during crystallization.

In summary, the non-phosgene polyurethane process provided by the present invention uses polycarbonate as a raw material to prepare polyurethane, which has the advantages of safe and harmless raw materials and environmental friendliness, and does not use any catalyst in the process. The polycarbonate After digestion and cracking reaction, the key intermediate of cyclic carbamate is formed, and the ring-opening polymerization is carried out with the cyclic carbamate to convert it into polyurethane, so the non-phosgene method polyurethane production process provided by the present invention is 1. High atomic economic benefits It is an innovative polyurethane process technology that can achieve the goals of green chemistry and circular economy.

Claims (10)

A non-phosgene polyurethane production process, which includes the following steps: Step 1, making polycarbonate and a monoalcohol amine compound undergo a digestion reaction, thereby obtaining a first intermediate product, the alcohol amine compound is selected from one of the following groups or Its combination: ethanolamine, 3-amino-1-propanol and 4-amino-1-butanol; step 2, subjecting the above-mentioned first intermediate product to a cleavage reaction, thereby obtaining a first compound containing cyclic carbamate Two intermediate products; and step three, subjecting the cyclic carbamate to ring-opening polymerization, thereby obtaining the polyurethane. According to the non-phosgene polyurethane production process described in Claim 1, the composition of the first intermediate product includes bisphenol A, diphenylene monourethane and diphenylene diurethane. According to the non-phosgene polyurethane production process described in Claim 1, the temperature range of the cracking reaction is 180-250°C. The non-phosgene method polyurethane production process as described in claim item 1, the cyclic carbamate is five-membered cyclic carbamate, six-membered cyclic carbamate or seven-membered cyclic carbamate esters. According to the non-phosgene polyurethane production process described in Claim 1, the ring-opening polymerization reaction is a cationic ring-opening polymerization reaction. According to the non-phosgene polyurethane production process described in claim item 5, the initiator of the cationic ring-opening polymerization comprises methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate or a combination thereof. The non-phosgene polyurethane production process as described in claim 1, further comprising a purification step of separating the cyclic carbamate from the second intermediate product. The non-phosgene polyurethane production process as described in Claim 7, the purification step comprises vacuum distillation, column chromatography, precipitation, crystallization, sublimation or any combination thereof. According to the non-phosgene polyurethane process described in claim 1, the polyurethane is a linear polyurethane with an average molecular weight ranging from 5,000 to 25,000 Da. A method for recycling waste polycarbonate, which uses the non-phosgene polyurethane process described in claims 1 to 8 to regenerate the waste polycarbonate into a linear polyurethane, and the average molecular weight range of the linear polyurethane is 5,000 ~20,000 Da.

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