A method for efficiently synthesizing polycarbonate polyols

Abstract

The application discloses a method for efficiently synthesizing polycarbonate polyols. The method uses polyhydric alcohol and small-molecule carbonate as raw materials, and generates polycarbonate polyols in the presence of a polycondensation catalyst and a phosphite. The method can significantly improve the reaction efficiency and reduce the reaction time, and the product has a low color number.

Description

Technical Field

[0001] This invention relates to a synthesis method, and more particularly to a method for efficiently synthesizing polycarbonate polyols. Background Technology

[0002] Polycarbonate polyols are a type of polyester polyol, specifically a special polyester polyol whose main molecular chain contains repeating carbonate groups. Polycarbonate polyols are considered among the highest-performing polyols currently available.

[0003] The synthesis of polycarbonate polyols involves a long reaction cycle, sometimes exceeding 30 hours. For example, the synthesis method for a phosphorus-containing polycarbonate polyol with a side chain described in patent CN114316239A requires approximately 35 hours. This prolonged reaction time not only affects production efficiency but also leads to higher color grades in the polycarbonate polyols, impacting downstream applications. Summary of the Invention

[0004] To address the above technical problems, this invention proposes a method for the efficient synthesis of polycarbonate polyols.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A highly efficient method for synthesizing polycarbonate polyols involves reacting polyols and small-molecule carbonates as raw materials in the presence of a polycondensation catalyst and phosphite to generate polycarbonate polyols.

[0007] As a preferred embodiment of the present invention, the mass ratio of the polyol to the small molecule carbonate is (30-70):(70-30), preferably (40-60):(60-40);

[0008] Preferably, the polyol is selected from one or more of the following: glycerol, trimethylolpropane, cyclohexanediol, neopentyl glycol, caprolactone diol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol.

[0009] Preferably, the small molecule carbonate is one or two of dimethyl carbonate, ethylene carbonate, diphenyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0010] As a preferred embodiment of the present invention, the polycondensation catalyst is one or more selected from dibutyltin dilaurate, stannous octanoate, dibutyltin octanoate, trimethylamine, triethylamine, tripropylamine, tetrabutyl titanate, tetraisopropyl titanate, and p-toluenesulfonic acid.

[0011] Preferably, the amount of the polycondensation catalyst is 10-60 ppm of the total mass of the polyol and the small molecule carbonate, more preferably 20-40 ppm.

[0012] As a preferred embodiment of the present invention, the phosphite is one or more selected from trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triphenyl phosphite, triisooctyl phosphite, and triisodecyl phosphite.

[0013] Preferably, the amount of the phosphite is 10-300 ppm of the total mass of the polyol and the small molecule carbonate, more preferably 30-100 ppm.

[0014] As a preferred embodiment of the present invention, the reaction process is a batch process, including an atmospheric pressure reaction stage, a hydrolysis reaction stage, and a vacuum reaction stage. The reaction is stopped after the product hydroxyl value reaches the designed hydroxyl value ±8mg KOH / g.

[0015] As a preferred embodiment of the present invention, the atmospheric pressure reaction stage is carried out in a temperature range of 160-270℃, preferably 190-210℃, and the reaction time is 3-8h, preferably 5-7h.

[0016] As a preferred embodiment of the present invention, in the hydrolysis reaction stage, 0.5-3% of the total mass of polyol and small molecule carbonate, preferably 1-2% water, needs to be added to the reaction system;

[0017] Preferably, the reaction time of the hydrolysis stage is 0.5-2 hours, more preferably 1-1.5 hours.

[0018] As a preferred embodiment of the present invention, the vacuum degree of the vacuum reaction stage is 1-9 kPa absolute pressure, preferably 1-2 kPa;

[0019] Preferably, the reaction time of the vacuum reaction stage is 5-15 hours, more preferably 8-11 hours.

[0020] The above reaction process can be carried out in a batch reactor.

[0021] This invention introduces phosphite into the preparation process of polycarbonate polyol, which can significantly improve reaction efficiency, shorten the total polymerization time, and help increase equipment capacity. The resulting product also has the advantage of a lower color number. Detailed Implementation

[0022] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0023] Unless otherwise specified, all raw materials and reagents used in the following embodiments of the present invention were purchased through commercial channels.

[0024] The testing method involved in this invention:

[0025] (1) Hydroxyl value: The hydroxyl value of polycarbonate polyols shall be tested in accordance with GB / T 12008.5-2009;

[0026] (2) Color number: The color of polycarbonate polyols is tested according to the Pt / Co colorimetric method.

[0027]

Example 1

[0028] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 4.3 kg of 3-methyl-1,5-pentanediol, 5 kg of dimethyl carbonate, and 50 ppm of triethyl phosphite and 30 ppm of tetraisopropyl titanate (based on the total mass of 3-methyl-1,5-pentanediol and dimethyl carbonate) were added sequentially. The reaction was initiated, and the temperature was raised to 210℃ under normal pressure and maintained for 7 hours. Once the temperature at the top of the distillation column significantly increased to the industry-standard threshold for ceasing further reaction, 0.26 kg of deionized water was added, and the reaction continued for 1.5 hours. Then, a vacuum was applied to 2 kPa, and the reaction continued for 10 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 60.5 mg KOH / g, a total reaction time of 18.5 hours, and a color number of 20.

[0029]

Example 2

[0030] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 2.3 kg of hexanediol, 2.1 kg of pentanediol, 5.2 kg of dimethyl carbonate, and 110 ppm of triethyl phosphite and 40 ppm of tetraisopropyl titanate (based on the total mass of hexanediol, pentanediol, and dimethyl carbonate) were added sequentially. The reaction was initiated, and the temperature was raised to 190°C under normal pressure and held for 6 hours. Once the temperature at the top of the distillation column significantly increased to the industry standard for determining when the reaction should cease, 0.29 kg of deionized water was added, and the reaction continued for 1 hour. Then, a vacuum was applied to 2 kPa, and the reaction continued for 8 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 62.5 mg KOH / g, a total reaction time of 15 hours, and a color number of 15.

[0031]

Example 3

[0032] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 4.8 kg of 1,5-pentanediol, 5.7 kg of dimethyl carbonate, and 100 ppm of triphenyl phosphite and 20 ppm of tetrabutyl titanate (based on the total mass of 1,5-pentanediol and dimethyl carbonate) were added sequentially. The reaction was initiated, and the temperature was raised to 200°C under normal pressure and held for 5 hours. Once the temperature at the top of the distillation column significantly increased to the industry-standard threshold for ceasing further reaction, 0.22 kg of deionized water was added, and the reaction continued for 1 hour. Then, a vacuum was applied to 1 kPa, and the reaction continued for another 8 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 61.1 mg KOH / g, a total reaction time of 14 hours, and a color number of 15.

[0033]

Example 4

[0034] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 2.1 kg of hexanediol, 2.3 kg of diethylene glycol, 4.7 kg of dimethyl carbonate, and 90 ppm of triethyl phosphite and 20 ppm of stannous octoate (based on the total mass of hexanediol, diethylene glycol, and dimethyl carbonate) were added sequentially. The reaction was initiated, and the temperature was raised to 200°C under normal pressure and held for 5 hours. Once the temperature at the top of the distillation column significantly increased to the industry standard for determining when the reaction should cease, 0.29 kg of deionized water was added, and the reaction continued for 1.5 hours. Then, a vacuum was applied to 2 kPa, and the reaction continued for 11 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 59.5 mg KOH / g, a total reaction time of 17.5 hours, and a color number of 20.

[0035]

Example 5

[0036] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 4.7 kg of 1,4-butanediol, 5.5 kg of dimethyl carbonate, and 90 ppm of triethyl phosphite and 30 ppm of tetrabutyl titanate (based on the total mass of 1,4-butanediol and dimethyl carbonate) were added sequentially. The reaction was initiated, and the temperature was raised to 200°C under normal pressure and held for 5 hours. Once the temperature at the top of the distillation column significantly increased to the industry standard for determining when the reaction should cease, 0.27 kg of deionized water was added, and the reaction continued for 1.5 hours. Then, a vacuum was applied to 1 kPa, and the reaction continued for 10 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 61.9 mg KOH / g, a total reaction time of 16.5 hours, and a color number of 20.

[0037]

Example 6

[0038] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 4.5 kg of 1,5-pentanediol, 5.1 kg of dimethyl carbonate, 100 ppm of tripropyl phosphite (based on the total mass of 1,5-pentanediol and dimethyl carbonate), and 40 ppm of p-toluenesulfonic acid were added sequentially. The reaction was initiated, and the temperature was raised to 210°C under normal pressure and held for 5 hours. Once the temperature at the top of the distillation column significantly increased to the industry-standard threshold for ceasing further reaction, 0.24 kg of deionized water was added, and the reaction continued for 1 hour. Then, a vacuum was applied to 1 kPa, and the reaction continued for 9 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 60.2 mg KOH / g, a total reaction time of 15 hours, and a color number of 15.

[0039] Comparative Example 1

[0040] In a 10L stainless steel reactor equipped with a stirrer, heater, distillation column, and column top condenser, under nitrogen protection and stirring conditions, 4.5 kg of 1,5-pentanediol and 5.1 kg of dimethyl carbonate were added sequentially, along with 100 ppm of tripropyl phosphite as a catalyst. The reaction was initiated, and the temperature was raised to 210°C at atmospheric pressure and held for 12 hours. Once the temperature at the top of the distillation column significantly increased to the industry standard for determining when the reaction should cease, 0.24 kg of deionized water was added, and the reaction was continued for 1 hour. Then, a vacuum was applied to 1 kPa, and the reaction continued for 25 hours. The mixture was then cooled and discharged to obtain polycarbonate polyol. Testing showed that the product had a hydroxyl value of 62.2 mg KOH / g, a total reaction time of 37 hours, and a color number of 50.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for efficiently synthesizing polycarbonate polyols, characterized in that, Polycarbonate polyols are produced by reacting polyols and small molecule carbonates in the presence of polycondensation catalysts and phosphites. The polycondensation catalyst is one or more of the following: dibutyltin dilaurate, stannous octanoate, dibutyltin octanoate, trimethylamine, triethylamine, tripropylamine, tetrabutyl titanate, tetraisopropyl titanate, and p-toluenesulfonic acid; the amount of the polycondensation catalyst is 10-60 ppm of the total mass of the polyol and the small molecule carbonate. The phosphite is one or more of trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triphenyl phosphite, triisooctyl phosphite, and triisodecyl phosphite; the amount of the phosphite is 10-300 ppm of the total mass of the polyol and the small molecule carbonate.

2. The method for efficiently synthesizing polycarbonate polyols according to claim 1, characterized in that, The mass ratio of the polyol to the small molecule carbonate is (30-70):(70-30).

3. The method for efficiently synthesizing polycarbonate polyols according to claim 2, characterized in that, The mass ratio of the polyol to the small molecule carbonate is (40-60):(60-40).

4. The method for efficiently synthesizing polycarbonate polyols according to claim 2, characterized in that, The polyol is selected from one or more of the following: glycerol, trimethylolpropane, cyclohexanediol, neopentyl glycol, caprolactone diol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol.

5. The method for efficiently synthesizing polycarbonate polyols according to claim 2, characterized in that, The small molecule carbonate is one or two of dimethyl carbonate, ethylene carbonate, diphenyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

6. The method for efficiently synthesizing polycarbonate polyols according to claim 1, characterized in that, The amount of the polycondensation catalyst used is 20-40 ppm of the total mass of the polyol and the small molecule carbonate.

7. The method for efficiently synthesizing polycarbonate polyols according to claim 1, characterized in that, The amount of the phosphite used is 30-100 ppm of the total mass of the polyol and small molecule carbonate.

8. The method for efficiently synthesizing polycarbonate polyols according to any one of claims 1-7, characterized in that, The reaction process is a batch process, including an atmospheric pressure reaction stage, a hydrolysis reaction stage, and a vacuum reaction stage. The reaction is stopped when the hydroxyl value of the product reaches the designed hydroxyl value ±8mgKOH / g.

9. The method for efficiently synthesizing polycarbonate polyols according to claim 8, characterized in that, The atmospheric pressure reaction stage is carried out at a temperature range of 160-270℃ for a reaction time of 3-8 hours.

10. The method for efficiently synthesizing polycarbonate polyols according to claim 9, characterized in that, The atmospheric pressure reaction stage is carried out at a temperature range of 190-210℃ for a reaction time of 5-7 hours.

11. The method for efficiently synthesizing polycarbonate polyols according to claim 8, characterized in that, The hydrolysis reaction stage requires the addition of 0.5-3% water by total mass of polyols and small molecule carbonates to the reaction system.

12. The method for efficiently synthesizing polycarbonate polyols according to claim 11, characterized in that, The hydrolysis reaction stage requires the addition of 1-2% water by total mass of polyols and small molecule carbonates to the reaction system.

13. The method for efficiently synthesizing polycarbonate polyols according to claim 11, characterized in that, The reaction time for the hydrolysis stage is 0.5-2 hours.

14. The method for efficiently synthesizing polycarbonate polyols according to claim 13, characterized in that, The reaction time for the hydrolysis stage is 1-1.5 hours.

15. The method for efficiently synthesizing polycarbonate polyols according to claim 8, characterized in that, The vacuum level during the vacuum reaction stage is 1-9 kPa absolute pressure.

16. The method for efficiently synthesizing polycarbonate polyols according to claim 15, characterized in that, The vacuum level during the vacuum reaction stage is 1-2 kPa absolute pressure.

17. The method for efficiently synthesizing polycarbonate polyols according to claim 15, characterized in that, The reaction time for the vacuum reaction stage is 5-15 hours.

18. The method for efficiently synthesizing polycarbonate polyols according to claim 17, characterized in that, The reaction time for the vacuum reaction stage is 8-11 hours.