A bio-based polyol suitable for supercritical carbon dioxide assisted foaming, a method of making, and a rigid polyurethane foam employing the same

Abstract

This application discloses a bio-based polyether polyol suitable for supercritical carbon dioxide-assisted foaming, its preparation method, and a rigid polyurethane foam using the same, belonging to the field of polyurethane technology. This application uses vegetable oil as raw material and obtains a bio-based polyol suitable for scCO2-assisted foaming through alcohol (amine) ester exchange, free radical Pudovik reaction, and epoxide anion ring-opening reaction. This polyol also possesses intrinsic flame-retardant properties. While using scCO2-assisted foaming, it eliminates the need for adding non-environmentally friendly physical foaming agents, and the main component of the raw material is biomass-derived vegetable oil, offering advantages such as green environmental protection and low cost, making it suitable for industrial-scale application.

Description

Technical Field

[0001] This application relates to the field of polyurethane technology, and more specifically, to a bio-based polyether polyol suitable for supercritical carbon dioxide-assisted foaming, its preparation method, and rigid polyurethane foam using the same. Background Technology

[0002] Rigid polyurethane foam is a porous polymer material prepared by foaming reaction using polyols and isocyanates as the main raw materials. Most of it has a closed-cell structure and exhibits excellent thermal insulation effect, high strength and good dimensional stability. It is widely used as a thermal insulation material in construction, industrial manufacturing and other fields.

[0003] Rigid polyurethane foam production typically uses physical blowing agents. Historically, fluorinated physical blowing agents such as chlorofluorocarbons (CFC-11) and hydrochlorofluorocarbons (HCFC-141b) have been ozone-depleting substances (ODS). Alternative fluorinated blowing agents, such as hydrofluorocarbons (HFC-245fa), are greenhouse gases with a high global warming potential (GWP). While hydrofluoroolefin blowing agents (HFO-1233zd) have a low GWP, their degradation product, trifluoroacetaldehyde, can further degrade into trifluoroacetic acid (TFA), a persistent new pollutant. Therefore, developing environmentally friendly rigid polyurethane foam foaming processes is a perpetual challenge for the sustainable development of the polyurethane industry.

[0004] Many of the aforementioned foaming agents have environmental drawbacks to varying degrees. In contrast, CO2 possesses excellent properties such as an ozone depletion potential (ODP) of 0, an extremely low gas content power (GWP) value, high foaming efficiency, non-flammability, and non-toxicity, making it a low-cost foaming agent with broad application prospects. However, due to CO2's extremely low boiling point and high volatility in air, it is necessary to explore the feasible applications of CO2 in polyurethane foaming.

[0005] Chinese invention patent CN201711282839.9, published on April 24, 2018, discloses a method for preparing rigid polyurethane foam using supercritical carbon dioxide (scCO2) as a physical blowing agent. It introduces a polyurethane composite polyether system suitable for scCO2-assisted foaming, with urethane ether and polycarbonate as the main polyethers. However, due to the limitations of technology at the time, this system still uses some non-environmentally friendly physical blowing agents, and the polyols are all from petrochemical sources. Therefore, there is still room for further improvement and refinement. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the purpose of this application is to provide a bio-based polyol suitable for supercritical carbon dioxide-assisted foaming, its preparation method, and a rigid polyurethane foam using the same. This application uses vegetable oil as a raw material and obtains a bio-based polyol suitable for scCO2-assisted foaming through alcohol (amine) ester exchange, free radical Pudovik reaction, and epoxide anion ring-opening reaction. Furthermore, this polyol possesses intrinsic flame-retardant properties.

[0007] To solve the above problems, the technical solution adopted in this application is as follows: A method for preparing a bio-based polyol, specifically comprising: S1, vegetable oil is subjected to alcohol (amine) ester exchange reaction with small molecule alcohol amine and small molecule polyol to obtain intermediate product A; S2, intermediate product A is reacted with a chemical containing a PH bond structure via a free radical Pudovik reaction to obtain intermediate product B; S3, intermediate product B is reacted with epoxide via an anionic ring-opening reaction to obtain the bio-based polyol.

[0008] Furthermore, the vegetable oil is selected from one or more of the following: jatropha oil, tung oil, tallow tree oil, castor oil, Chinese pistache oil, and bark tree oil, with tung oil and castor oil being preferred.

[0009] Furthermore, the small molecule polyol is selected from one, two, or three of glycerol, trimethylolpropane, and pentaerythritol, and the small molecule alkanolamine is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine.

[0010] Furthermore, in S1, the mass ratio of small molecule alkanolamines to the total mass of small molecule alkanolamines and small molecule polyols is 40-100%. Specifically, S1 can use only alkanolamines or a mixture of alkanolamines and polyols.

[0011] Furthermore, the PH-bonded chemical is selected from one or more of methyl methyl hypophosphite (MMP), methyl phenyl hypophosphite (MPP), ethyl phenyl hypophosphite (EPP), diethyl phosphite (DEP), or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO).

[0012] Further, the epoxide is one or more of ethylene oxide, propylene oxide, and butane oxide; preferably, the epoxide is a mixture of propylene oxide and ethylene oxide, wherein the mass content of ethylene oxide in the mixture is 0-15%. That is, it can be propylene oxide or a mixture of propylene oxide and ethylene oxide.

[0013] Furthermore, in S2, the free radical initiator used in the Pudovik reaction is one of azobisisobutyronitrile, azobisisovalerate, azobiscyclohexylformitrile, or dimethyl azobisisobutyrate.

[0014] Furthermore, in S3, the mass ratio of intermediate product B to epoxide is 100:(35-150).

[0015] Bio-based polyols prepared using the aforementioned method.

[0016] Rigid polyurethane foam, the formulation of which uses the aforementioned bio-based polyols.

[0017] Compared to existing technologies, the beneficial effects of this application are as follows: This application uses vegetable oil as raw material and obtains a bio-based polyol suitable for scCO2-assisted foaming through alcohol (amine) ester exchange, free radical Pudovik reaction, and epoxide anion ring-opening reaction. This polyol also has intrinsic flame retardant properties.

[0018] The preparation of rigid polyurethane foam using the bio-based polyols of this application eliminates the need for non-environmentally friendly physical foaming agents while employing scCO2-assisted foaming. Furthermore, the main component of the raw material is biomass-derived plant oil, which has the advantages of being green, environmentally friendly, and low-cost, making it suitable for industrial-scale promotion and application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0020] For the purposes of this application, it should be understood that various alternative variations and sequences of steps may be employed in this application unless expressly stated to the contrary. Furthermore, except in any operational instance or otherwise stated, all numerical values ​​indicating the amount of an ingredient as used, for example, in the specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless stated to the contrary, the numerical parameters listed in the following specification and appended claims are approximate values ​​that may vary depending on the desired properties to be obtained in this application. At least, without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be interpreted at least based on the reported significant figures and by applying ordinary rounding techniques.

[0021] While the numerical ranges and parameters listed in this application are approximate, the values ​​listed in the specific embodiments are reported as accurately as possible. However, any numerical value inherently contains some error that must be caused by the standard deviation found in its respective test measurements.

[0022] The polyols used in this application are mainly composed of four categories of raw materials: vegetable oils, small molecule polyols and small molecule alkanolamines, chemicals containing pH bonds, and epoxides. The vegetable oils are selected from one or more of the following: jatropha oil, tung oil, tallow tree oil, castor oil, Chinese pistache oil, and bark oil, with tung oil and castor oil being preferred. The polyols and alkanolamines are one or more of the following: glycerol, trimethylolpropane, pentaerythritol, monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine. Specifically, alkanolamines or mixtures of alkanolamines and polyols can be used, with the mass content of alkanolamines in the mixture being 40-100%. The chemicals containing pH bonds are... The epoxide is one or more of methyl hypophosphite (MMP), methyl phenyl hypophosphite (MPP), ethyl phenyl hypophosphite (EPP), diethyl phosphite (DEP), or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO); the epoxide is one, two, or three of ethylene oxide, propylene oxide, and butane oxide, preferably propylene oxide, or a mixture of propylene oxide and ethylene oxide, wherein the mass content of ethylene oxide in the mixture is 0-15%.

[0023] The specific preparation method is as follows: The first step involves an alcohol (amine) transesterification reaction between vegetable oil and polyols and alkanolamines. The mass ratio of vegetable oil to polyols and alkanolamines is 100:(4-15). The measured amounts of vegetable oil, polyols, and alkanolamines are placed in a reaction vessel, purged with nitrogen, and heated to 135-220℃. The reaction is carried out for 2-6 hours to obtain intermediate product A.

[0024] The second step involves a free radical Pudovik reaction between intermediate product A and a chemical containing a PH bond structure. The mass ratio of intermediate product A to the chemical containing the PH bond structure is 100:(8-25). Intermediate product A is cooled to 30-45°C, and a portion of intermediate product A is taken out to dissolve the free radical initiator. The initiator content in intermediate product A is 0.5-8% by mass, and the dissolved intermediate product A constitutes 5-10% of the total reactant mass. The remaining intermediate product A and the chemical containing the PH bond structure are placed in a reaction vessel, purged with nitrogen, and heated to 60-90°C. The mixture of intermediate product A with dissolved free radical initiator is slowly and continuously added to the reaction system using a syringe pump over 2-4 hours, and the reaction continues for 0.5-2 hours to obtain intermediate product B. The recommended type of free radical initiator is an azo radical initiator, specifically one of azobisisobutyronitrile (AIBN), azobisisovalerate (AMBN), azobiscyclohexylformonitrile (ACCN), or dimethyl azobisisobutyrate (AIBME).

[0025] The third step involves an anionic ring-opening reaction between intermediate product B and the epoxide. The mass ratio of intermediate product B to epoxide is 100:(35-150). A measured amount of intermediate product B is added to a high-pressure reactor, along with 0.07-1.0% (by mass) of potassium hydroxide (KOH). The reactor is heated to 80-100°C and reacted for 0.5-1 hour. The reactor is then purged with nitrogen to remove air and a vacuum is created. Under vacuum, the epoxide is gradually added, and the temperature is raised to 70-105°C. During the reaction, the pressure in the high-pressure reactor is controlled to not exceed 0.25 MPa. After all the measured epoxide has been added to the high-pressure valve, the reactor pressure is observed to gradually decrease to 0 MPa, and the reaction continues for another 0.5 hours. Add an appropriate amount of 37% hydrochloric acid solution to the reaction system, stir at 50-80℃ for 20-30 minutes until the pH of the reaction system reaches neutrality; continue to add an appropriate amount of magnesium silicate adsorbent and stir for 20-30 minutes, filter and dehydrate under vacuum to obtain the bio-based polyol product of this application.

[0026] The present application will be further described below with reference to specific embodiments.

[0027] Example 1 A method for preparing a castor oil-based phosphorus-nitrogen-containing polyether polyol includes the following steps: (1) Alkylamine transesterification reaction: 1000 g of castor oil and 80 g of triethanolamine were weighed and added to a reaction vessel equipped with a stirrer, thermometer and nitrogen protection device. Nitrogen was introduced to replace the air in the vessel and the temperature was raised to 180℃. The reaction was carried out under stirring for 4 h to obtain intermediate product A1.

[0028] (2) Free radical Pudovik reaction: The intermediate product A1 was cooled to 40°C, and 80 g of intermediate product A1 was dissolved in 4 g of azobisisobutyronitrile (AIBN) for later use. The remaining 920 g of intermediate product A1 and 160 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were added to the reaction vessel. After nitrogen purging, the temperature was raised to 80°C. The intermediate product A1 dissolved in AIBN was continuously added to the reaction system by a syringe pump over 3 h. After the addition was completed, the reaction was continued for 1 h to obtain intermediate product B1.

[0029] (3) Ring-opening reaction of epoxide anion: 1000 g of intermediate product B1 was weighed and added to a high-pressure reactor, along with 1.2 g of potassium hydroxide (KOH). The temperature was raised to 90°C and the reaction was carried out for 1 h. Subsequently, the air inside the reactor was replaced with nitrogen and a vacuum was drawn. Under vacuum, 800 g of propylene oxide was continuously added, and the reaction temperature was controlled at 85-100°C, while the pressure inside the reactor was controlled to not exceed 0.25 MPa. After the propylene oxide was added, the pressure inside the reactor was gradually reduced to 0 MPa, and the reaction was continued for 0.5 h. After the reaction was completed, 37% hydrochloric acid solution was added to neutralize the system to a neutral pH, and a small amount of magnesium silicate adsorbent was added. The mixture was stirred at 60°C for 30 min, filtered, and then dehydrated under vacuum to obtain 1795.3 g of castor oil-based phosphorus-nitrogen-containing bio-based polyether polyol P-1. The hydroxyl value of the product was 322.2 mgKOH / g, and the viscosity was 1550 mPa.s.

[0030] The resulting product P-1 is a light brownish-yellow viscous liquid containing a long-chain hydrophobic structure introduced by vegetable oil segments, a nitrogen-containing structure introduced by triethanolamine, a phosphorus-containing structure introduced by DOPO, and a polyether hydroxyl segment formed by ring opening of propylene oxide. It can be used as a reactive polyol component in supercritical carbon dioxide-assisted foaming polyurethane rigid foam systems.

[0031] Example 2 A method for preparing a tung oil-based phosphorus-nitrogen-containing polyether polyol includes the following steps: (1) Alkylamine transesterification reaction: Weigh 1000 g of tung oil, 60 g of diethanolamine and 40 g of glycerol and add them to the reaction vessel. After nitrogen purging, heat to 170℃ and stir for 5 h to obtain intermediate product A2.

[0032] (2) Free radical Pudovik reaction: The intermediate product A2 was cooled to 35°C, and 90 g of intermediate product A2 was dissolved in 3.5 g of azobisisovalerate (AMBN) for later use. The remaining 910 g of intermediate product A2 and 120 g of diethyl phosphite (DEP) were added to the reaction vessel, and the temperature was raised to 70°C under nitrogen protection. The intermediate product A2 containing AMBN was continuously added to the reaction system over 2.5 h, and the reaction was continued for 1 h to obtain intermediate product B2.

[0033] (3) Ring-opening reaction of epoxide anions: 1000 g of intermediate product B2 was weighed and added to a high-pressure reactor, along with 0.9 g of KOH. The reaction was carried out at 90°C for 0.5 h. After nitrogen purging and evacuation, 810 g of propylene oxide and 90 g of ethylene oxide were continuously added as a mixed epoxide. The reaction temperature was controlled at 80-100°C, and the reaction pressure did not exceed 0.25 MPa. After the epoxide addition was complete and the pressure inside the reactor dropped to 0 MPa, the reaction was continued for another 0.5 h. The mixture was then neutralized to neutral with 37% hydrochloric acid, treated with magnesium silicate adsorbent, filtered, and dehydrated under vacuum to obtain 1881.1 g of tung oil-based phosphorus-nitrogen-containing bio-based polyether polyol P-2, with a hydroxyl value of 341.7 mgKOH / g and a viscosity of 782 mPa.s.

[0034] In this embodiment, the unsaturated structure in tung oil is conducive to the introduction of compounds containing pH bonds; the ring-opening of propylene oxide and a small amount of ethylene oxide can adjust the hydroxyl value and viscosity of the resulting polyol, and optimize its hydrophilicity and compatibility with supercritical carbon dioxide.

[0035] Example 3 A method for preparing a castor oil-based arylphosphonate-modified polyether polyol includes the following steps: (1) Alkylamine transesterification reaction: 1000 g of castor oil, 60 g of trimethylolpropane and 40 g of triethanolamine were weighed and added to the reaction vessel. The temperature was raised to 160°C under nitrogen protection and the reaction was carried out for 3.5 h to obtain intermediate product A3.

[0036] (2) Free radical Pudovik reaction: The intermediate product A3 was cooled to 40°C, and 100 g of intermediate product A3 was dissolved in 5 g of azobiscyclohexylformonitrile (ACCN) for later use. The remaining 900 g of intermediate product A3 and 200 g of methyl phenyl hypophosphite (MPP) were added to the reaction vessel, and the temperature was raised to 78°C under nitrogen protection. The intermediate product A3 containing ACCN was continuously added to the reaction system over 4 h, and the reaction was continued for 1.5 h to obtain intermediate product B3.

[0037] (3) Ring-opening reaction of epoxide anion: 1000 g of intermediate product B3 was weighed and added to a high-pressure reactor, along with 3.5 g of KOH. The reaction was carried out at 95℃ for 1 h. After nitrogen purging and vacuuming, 600 g of propylene oxide was continuously added. The reaction temperature was controlled at 90-105℃, and the pressure was controlled at no more than 0.25 MPa. After the addition was completed and the pressure in the reactor dropped to 0 MPa, the reaction was continued for 0.5 h. After neutralization with hydrochloric acid, adsorption with magnesium silicate, filtration, and vacuum dehydration, 1577.3 g of castor oil-based arylphosphonate modified bio-based polyether polyol P-3 was obtained, with a hydroxyl value of 288.5 mgKOH / g and a viscosity of 1224 mPa.s.

[0038] In this embodiment, the introduction of an aryl phosphorus-containing structure through methyl phenyl hypophosphite can improve the flame retardant contribution of the resulting polyol in the rigid polyurethane foam system, and the subsequent ring-opening with propylene oxide can enhance the reactivity and formulation applicability.

[0039] Example 4 A method for preparing a *Pistacia chinensis* oil-based phosphorus-nitrogen-containing polyether polyol includes the following steps: (1) Alkylamine transesterification reaction: 1000 g of Coptis chinensis oil and 100 g of triisopropanolamine were weighed and added to the reaction vessel. After nitrogen purging, the temperature was raised to 190℃ and stirred for 4 h to obtain intermediate product A4.

[0040] (2) Free radical Pudovik reaction: The intermediate product A4 was cooled to 45°C, and 85 g of intermediate product A4 was dissolved with 4 g of dimethyl azobisisobutyrate (AIBME) for later use. The remaining 915 g of intermediate product A4 and 150 g of ethyl phenyl hypophosphite (EPP) were added to the reaction vessel, and the temperature was raised to 75°C under nitrogen protection. The intermediate product A4 containing dissolved AIBME was continuously added to the reaction system over 3 h, and the reaction was continued for 1 h to obtain intermediate product B4.

[0041] (3) Ring-opening reaction of epoxide anion: 1000 g of intermediate product B4 was weighed and added to a high-pressure reactor, along with 4.8 g of KOH. The reaction was carried out at 85°C for 1 h. After nitrogen purging and evacuation, 1000 g of propylene oxide was continuously added. The reaction temperature was controlled at 80-100°C, and the reaction pressure did not exceed 0.25 MPa. After the addition of propylene oxide was completed and the pressure dropped to 0 MPa, the reaction was continued for 0.5 h. After neutralization with hydrochloric acid, adsorption with magnesium silicate, filtration, and vacuum dehydration, 1958.6 g of *Pistacia chinensis* oil-based phosphorus-nitrogen-containing bio-based polyether polyol P-4 was obtained, with a hydroxyl value of 299.3 mgKOH / g and a viscosity of 1080 mPa.s.

[0042] This embodiment illustrates that, in addition to castor oil and tung oil, other vegetable oils can also be used as raw material sources for the bio-based polyols of this application. Bio-based polyether polyols suitable for supercritical carbon dioxide-assisted foaming can be prepared through alkanolamine ester exchange, free radical Pudovik reaction and epoxide ring-opening reaction.

[0043] Example 5 A method for preparing castor oil-based phosphorus-nitrogen-containing polyether polyol suitable for water / supercritical carbon dioxide composite foaming systems includes the following steps: (1) Alkylamine transesterification reaction: 1000 g of castor oil, 70 g of diethanolamine and 40 g of glycerol were weighed and added to a reaction vessel equipped with a stirrer, thermometer and nitrogen protection device. Nitrogen was introduced to replace the air in the vessel and the temperature was raised to 175℃. The reaction was carried out for 4 h under stirring to obtain intermediate product A5.

[0044] (2) Free radical Pudovik reaction: The intermediate product A5 was cooled to 40°C, and 90 g of intermediate product A5 was dissolved in 4 g of azobisisobutyronitrile (AIBN) for later use. The remaining 910 g of intermediate product A5 and 140 g of diethyl phosphite (DEP) were added to the reaction vessel, purged with nitrogen, and heated to 75°C. The intermediate product A5 containing dissolved AIBN was continuously added to the reaction system over 3 h using a syringe pump. After the addition was completed, the reaction was continued for 1 h to obtain intermediate product B5.

[0045] (3) Anionic ring-opening reaction of epoxides: 1000 g of intermediate product B5 was weighed and added to a high-pressure reactor, along with 1.5 g of potassium hydroxide (KOH). The temperature was raised to 90°C and the reaction was carried out for 1 h. Subsequently, the air inside the reactor was replaced with nitrogen and a vacuum was drawn. Under vacuum, 790 g of propylene oxide and 60 g of ethylene oxide mixed epoxides were continuously added. The reaction temperature was controlled at 80-100°C, and the pressure inside the reactor did not exceed 0.25 MPa. After the mixed epoxides were added, the pressure inside the reactor was gradually reduced to 0 MPa, and the reaction was continued for 0.5 h. After the reaction was completed, 37% hydrochloric acid solution was added to neutralize the system to a neutral pH, and a small amount of magnesium silicate adsorbent was added. The mixture was stirred at 60°C for 30 min, filtered, and then dehydrated under vacuum to obtain 1832.0 g of castor oil-based phosphorus-nitrogen-containing bio-based polyether polyol P-5. The hydroxyl value of the product was 309.3 mg KOH / g, and the viscosity was 1180 mPa•s.

[0046] The resulting product P-5 contains castor oil long-chain structures, nitrogen-containing alcohol amine structures, phosphorus-containing structures, and polyether segments formed by ring-opening of propylene oxide and a small amount of ethylene oxide. The introduction of a small amount of ethylene oxide segments improves the compatibility of the polyol with the aqueous composite system, making it suitable for polyurethane rigid foam systems synergistically foamed with water-based foaming agents and supercritical carbon dioxide.

[0047] Example 6 A method for preparing a tung oil-based phosphorus-nitrogen-containing polyether polyol includes the following steps: (1) Alkylamine transesterification reaction: 1000 g of tung oil, 60 g of triethanolamine and 60 g of trimethylolpropane were weighed and added to a reaction vessel equipped with a stirrer, thermometer and nitrogen protection device. Nitrogen was introduced to replace the air in the vessel and the temperature was raised to 170℃. The reaction was carried out for 5 h under stirring to obtain intermediate product A6.

[0048] (2) Free radical Pudovik reaction: The intermediate product A6 was cooled to 40°C, and 100 g of intermediate product A6 was dissolved in 5 g of azobisisovalerate (AMBN) for later use. The remaining 900 g of intermediate product A6 and 180 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were added to the reaction vessel. After nitrogen purging, the temperature was raised to 80°C. The intermediate product A6 dissolved in AMBN was continuously added to the reaction system using a syringe pump over 3.5 h. After the addition was completed, the reaction was continued for 1 h to obtain intermediate product B6.

[0049] (3) Anionic ring-opening reaction of epoxides: 1000 g of intermediate product B6 was weighed and added to a high-pressure reactor, along with 2.2 g of potassium hydroxide (KOH). The temperature was raised to 95℃ and the reaction was carried out for 1 h. Subsequently, the air inside the reactor was replaced with nitrogen and a vacuum was drawn. Under vacuum, 475 g of propylene oxide and 35 g of ethylene oxide mixed epoxides were continuously added. The reaction temperature was controlled at 85-105℃, and the pressure inside the reactor did not exceed 0.25 MPa. After the mixed epoxides were added, the pressure inside the reactor was gradually reduced to 0 MPa, and the reaction was continued for 0.5 h. After the reaction was completed, 37% hydrochloric acid solution was added to neutralize the system to a neutral pH, and a small amount of magnesium silicate adsorbent was added. The mixture was stirred at 60℃ for 30 min, filtered, and then dehydrated under vacuum to obtain 1426.4 g of tung oil-based phosphorus-nitrogen-containing bio-based polyether polyol P-6. The hydroxyl value of the product was 337.4 mg KOH / g, and the viscosity was 2980 mPa•s.

[0050] The resulting product, P-6, uses tung oil as a bio-based raw material. Nitrogen-containing and polyhydroxy structures are introduced through transesterification reactions involving both alkanolamines and polyols. Furthermore, phosphorus-containing structures are introduced via DOPO, and the polyether segment structure is adjusted through ring-opening with a mixture of propylene oxide and ethylene oxide. This polyol possesses bio-based origin, phosphorus and nitrogen-containing flame-retardant modification characteristics, and compatibility with water-based foaming / supercritical carbon dioxide-assisted foaming systems.

[0051] To further illustrate the application of the bio-based polyether polyols in rigid polyurethane foam, the polyether polyols obtained in Examples 1-6 were used as part of a composite polyether in a rigid polyurethane foam system foamed with both water and supercritical carbon dioxide. Rigid polyurethane foams were prepared and compared with formulations that did not contain the polyols from the above examples. Specific application formulations are shown in Table 1.

[0052] Table 1. Formulations for rigid polyurethane foam applications (by parts by weight)

[0053] The properties of the obtained rigid polyurethane foam are shown in Table 2.

[0054] Table 2. Performance test results of rigid polyurethane foam

[0055] As can be seen from Table 2, compared with the control sample, rigid polyurethane foam with relatively ideal performance was prepared by using the bio-based polyether polyol of this application for scCO2-assisted foaming.

Claims

1. A method for preparing a bio-based polyol, characterized in that, Specifically: S1, vegetable oil is subjected to alcohol (amine) ester exchange reaction with small molecule alcohol amine and small molecule polyol to obtain intermediate product A; S2, intermediate product A is reacted with a chemical containing a PH bond structure via a free radical Pudovik reaction to obtain intermediate product B; S3, intermediate product B is reacted with epoxide via an anionic ring-opening reaction to obtain the bio-based polyol.

2. A method for preparing a bio-based polyol according to claim 1, characterized in that, The plant oil is selected from one or more of the following: jatropha oil, tung oil, tallow tree oil, castor oil, Chinese pistache oil, and bark tree oil, with tung oil and castor oil being preferred.

3. A method for preparing a bio-based polyol according to claim 1, characterized in that, The small molecule polyol is selected from one, two, or three of glycerol, trimethylolpropane, and pentaerythritol, and the small molecule alkanolamine is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine.

4. A method for preparing a bio-based polyol according to claim 1 or 3, characterized in that, In S1, the mass ratio of small molecule alcohol amines to the total mass of small molecule alcohol amines and small molecule polyols is 40-100%.

5. A method for preparing a bio-based polyol according to claim 1, characterized in that, The PH-bonded chemical is selected from one or more of methyl hypophosphite, phenyl hypophosphite, ethyl phenyl hypophosphite, diethyl phosphite, or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

6. A method for preparing a bio-based polyol according to claim 1, characterized in that, The epoxide is one or more of ethylene oxide, propylene oxide, and butane oxide; preferably, the epoxide is a mixture of propylene oxide and ethylene oxide, wherein the mass content of ethylene oxide in the mixture is 0-15%.

7. A method for preparing a bio-based polyol according to claim 1, characterized in that, In S2, the free radical initiator used in the Pudovik reaction is one of azobisisobutyronitrile, azobisisovalerate, azobiscyclohexylformitrile, or dimethyl azobisisobutyrate.

8. A method for preparing a bio-based polyol according to claim 1, characterized in that, In S3, the mass ratio of intermediate product B to epoxide is 100:(35-150).

9. A bio-based polyol prepared by any one of claims 1 to 8.

10. Rigid polyurethane foam, characterized in that, Its formulation uses the bio-based polyol described in claim 9.

Images