A bio-based polyol, and a method of making and using the same

Abstract

The application provides a kind of bio-based polyol and its preparation method and application.The preparation method contains the following steps: mixing alcohol with catalyst, adding epoxy soybean oil to react, removing catalyst and VOC after treatment, adding epoxide, natural oil and small molecule polyol reaction and ester exchange.The application adjusts the viscosity, functionality and molecular weight of the product through specific ester exchange reaction, and improves the compatibility of the product by adding epoxide, so that it can meet the needs of various applications.The bio-based polyether polyol synthesized by the method has good performance effect in soft foam, slow rebound and CASE field.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a bio-based polyol, its preparation method, and its application. Background Technology

[0002] Polyurethane is a high-performance polymer material, its basic synthesis consisting of the reaction of polyester or polyether polyols with isocyanates. Due to its excellent foaming properties and ease of handling, its products are widely used in insulation, footwear, furniture, adhesives, elastomers, coatings, and imitation leather. In downstream applications of polyurethane foam, especially in adhesives, its use is often closely related to, and even directly related to, people's daily lives. With increasing emphasis on food safety and environmental awareness, more and more consumers want their everyday skin-contact and food packaging products to be safe and environmentally friendly, ideally made from bio-based materials. Traditional polyether polyols, whose core components are petrochemical raw materials, are mostly non-renewable resources. This invention proposes a bio-based polyether polyol. The product has a high bio-based content, does not generate solid waste or waste liquid, and the resulting product exhibits advantages such as high peel strength, good hydrolysis resistance, and suitable reactivity in applications such as flexible foam, slow rebound, and CASE.

[0003] CN 104945256 B discloses a method for preparing vegetable oil polyols, the preparation steps of which include: a) epoxidation reaction of vegetable oil: vegetable oil undergoes an epoxidation reaction in an environment of formic acid / acetic acid and hydrogen peroxide to obtain epoxidized vegetable oil; b) ring-opening reaction: the epoxidized vegetable oil obtained in step a) is reacted with water under high temperature and high pressure in the presence of acidic substances to obtain the vegetable oil polyols described in this invention. This patented method requires high temperature and high pressure, which is demanding.

[0004] CN 101830802 A describes a method for preparing epoxidized soybean oil-based polyols from epoxidized soybean oil. The method involves adding epoxidized soybean oil, anhydrous methanol, solvent, water, and catalyst to an autoclave, purging with nitrogen to create a vacuum, and heating at a rate of 2–10 °C / min to 100–160 °C. The reaction pressure is autogenous, and the reaction is carried out for 12–20 hours to obtain the product. After the reaction is complete, the catalyst is filtered to obtain solvent, methanol, and epoxidized soybean oil-based polyols by vacuum distillation. The filtered catalyst and the distilled solvent and methanol are directly used in the next reaction, achieving recycling. However, this reaction is time-consuming and involves high temperatures, making it unsuitable for industrial applications.

[0005] CN 109320709 A discloses a method for preparing reactive flame-retardant polyether polyols by phosphorylation of epoxidized soybean oil, relating to the field of rigid foam polyether polyols. The preparation method includes the following steps: (1) adding phosphoric acid and solvent to a three-necked flask to obtain a phosphoric acid solution; (2) dissolving epoxidized soybean oil in a solvent to obtain an epoxidized soybean oil solution, then adding the epoxidized soybean oil solution dropwise to the phosphoric acid solution, reacting for 1-6 hours after the addition, removing the solvent after the reaction is complete to obtain phosphoricated epoxidized soybean oil; (3) adding an alkaline catalyst to the phosphoricated epoxidized soybean oil and adjusting the pH to 8-14 to obtain alkaline phosphoricated epoxidized soybean oil. This patent requires an additional solvent, acetone, and requires solvent removal, making the production process very complex.

[0006] CN 115572385 A relates to a method for preparing polyether polyols, specifically a method for preparing plant-based polyether polyols. This invention uses epoxidized soybean oil as a starting agent, reacts it with a small molecule alcohol, then combines it with sucrose or solid sorbitol, and further reacts it with a mixture of castor oil and hydrogenated soybean oil, and propylene oxide to obtain a polyether polyol with high pentane miscibility. The small molecule alcohol is one or more of diethylene glycol, glycerol, or propylene glycol, and the mass ratio of epoxidized soybean oil, castor oil, and hydrogenated soybean oil is 1:(1-2):(1.8-8.1). The plant-based content of the polyether polyol in this invention accounts for 45-75% of the total raw material mass, and the polyether polyol does not separate or become cloudy, resulting in a plant-based polyether polyol with high pentane miscibility. However, the ring-opening stage of the epoxidized soybean oil also requires high temperature and pressure, leading to excessive consumption of utilities.

[0007] However, in existing patented technologies, the ring-opening process of epoxidized soybean oil often involves high temperature, high pressure, and the addition of solvents. Because epoxidized soybean oil contains multiple epoxy groups, it can react not only with small molecule alcohol initiators but also with already ring-opened epoxidized soybean oil to form multiple polymerized products. These polymers have large molecular weights, high viscosity, high functionality, and poor reactivity, making them difficult to apply to flexible foam and CASE production. Summary of the Invention

[0008] To address the aforementioned technical problems, one objective of this invention is to provide a method for synthesizing bio-based polyether polyols. The bio-based polyether polyols synthesized by this method solve the above-mentioned problems and exhibit good performance in the fields of flexible foam, slow rebound, and CASE.

[0009] To achieve the above-mentioned effects, the present invention adopts the following technical solution:

[0010] A method for preparing a bio-based polyol, the method comprising the following steps:

[0011] S1: Mix the alcohol with the catalyst;

[0012] S2: Add epoxidized soybean oil to react;

[0013] S3: Post-treatment to remove unreacted small molecule alcohols and VOCs;

[0014] S4: Add epoxides, natural oils and small molecule polyols for reaction and transesterification.

[0015] In one embodiment of the present invention, the alcohol in S1 is a C1-C4 monofunctional alcohol, preferably methanol and / or ethanol.

[0016] In one embodiment of the present invention, the catalyst in S1 is an acidic catalyst, preferably one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and tetrafluoroboric acid.

[0017] In one embodiment of the present invention, when epoxidized soybean oil is added to S2, the ratio of alcohol to epoxidized soybean oil is (0.05-0.6):1, preferably (0.05-0.4):1.

[0018] In one embodiment of the present invention, the epoxy value of the epoxidized soybean oil added in S2 is 4.0-6.5.

[0019] In one embodiment of the invention, the epoxide in S4 is a C2-C4 epoxide, preferably propylene oxide and / or ethylene oxide.

[0020] In one embodiment of the present invention, the small molecule polyol in S4 is a polyol with a C2 to C4 function of 2 to 4, preferably one or more of ethylene glycol, propylene glycol, diethylene glycol, glycerol, and butylene glycol.

[0021] In one embodiment of the present invention, the natural oil in S4 is a triglyceride structure oil, preferably one or more of palm oil, soybean oil, cottonseed oil, and castor oil; preferably, the mass ratio of epoxidized soybean oil, natural oil, small molecule polyol, and epoxide in S4 is 1:(0.1-0.6):(0.02-0.1):(0.1-0.5), more preferably 1:(0.2-0.4):(0.03-0.06):(0.2-0.5).

[0022] In one embodiment of the present invention, the catalyst in S4 is an amine and / or imidazole, preferably one or more of trimethylamine, dimethylamine, N,N-dimethylcyclohexylamine, and N-methylimidazole; preferably, the concentration of the catalyst is 2000-10000 ppm, more preferably 4000-6000 ppm.

[0023] In one embodiment of the present invention, the temperature in S4 is 90°C to 115°C.

[0024] Another objective of this invention is to provide a bio-based polyol.

[0025] A bio-based polyol, wherein the polyol is prepared by the above-described preparation method, and the raw materials of the bio-based polyol include: epoxidized soybean oil, alcohol, natural oil, polyol, and epoxide; and the alcohol content used is 5% to 20% based on the total amount of the above-described polymerized monomers as 100%.

[0026] In one embodiment of the present invention, the intermediate bio-based polyol obtained by reacting alcohol with epoxidized soybean oil has a molecular weight of 1000-1200 as its main component, and a first byproduct with a molecular weight of 1900-2200. The first byproduct is generated by ring-opening polymerization of a molecule of hydroxyl-containing epoxidized soybean oil polyether and a molecule of soybean oil derivative containing epoxy groups. The second byproduct has a molecular weight of 2800-3300 and is generated by ring-opening polymerization of a molecule of the first byproduct and a molecule of soybean oil derivative containing epoxy groups.

[0027] In one embodiment of the present invention, the bio-based polyol has a functionality of 1 to 4, a hydroxyl value of 60 to 170 mg KOH / g, and a viscosity of 500 to 8000 mPa·s at 25°C.

[0028] Another object of the present invention is to provide a use of a bio-based polyol.

[0029] Use of a bio-based polyol, wherein the polyol is prepared by the above-described preparation method or is the polyol described above, wherein the polyol is used in polyurethane foam, preferably in flexible polyurethane foam.

[0030] Another object of the present invention is to provide a polyurethane flexible foam product.

[0031] A polyurethane flexible foam product, wherein the product is prepared using the polyol obtained by the above-described preparation method, or the polyol described above.

[0032] For example, the reactions involved in S1-S4 of the present invention are as follows:

[0033] (1) S2, epoxidized soybean oil undergoes a ring-opening addition reaction with a small molecule alcohol under the action of a catalyst.

[0034]

[0035] (2) In the transesterification reaction in S4, any ester bond reacts with the exposed alcohol group, resulting in transesterification.

[0036]

[0037] This reaction is reversible, and the ester and alcohol bonds can freely combine, resulting in no fixed product structure.

[0038] (3) The addition of PO in S4

[0039]

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) Compared with other epoxidized soybean oil polyethers, its S2 stage product does not require solvents or pressure, and has low viscosity, which is beneficial for its application in the field of flexible foam.

[0042] (2) In the S4 stage of this process, small molecule alcohols and natural oils are further introduced, which further reduces the viscosity of the product and improves its lipophilicity, thus significantly increasing the application areas of the product.

[0043] (3) In the S4 stage of this process, propylene oxide is introduced, which extends the carbon chain of the hydroxyl groups, making the foam less prone to collapse in flexible foam applications. At the same time, it increases hydrophilicity, which helps with the mixing with other foaming materials. Detailed Implementation

[0044] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0045] Experimental materials:

[0046] Epoxidized soybean oil A, Guangdong Fufeng Chemical Co., Ltd., standard product. Epoxy value (%) is 6.2 (GB / T1677), acid value (KOH) is 0.53 (GB / T1668), moisture (%) ≤0.1 (GB5009.229).

[0047] Epoxidized soybean oil B, from Haierma Technology Co., Ltd., standard product. Epoxy value (%) is 6.1 (GB / T1677), acid value (KOH) is 0.62 (GB / T1668), moisture (%) ≤0.1 (GB5009.229).

[0048] Anhydrous methanol, Beijing Innoka Technology, AR99.5%.

[0049] Anhydrous ethanol, Beijing Innovent Technology, AR99.7%

[0050] Tetrafluoroboric acid, Guoyao Reagent, 40% aqueous solution.

[0051] Palm oil, COFCO, national standard 24℃ palm oil. Acid value (KOH) ≤ 0.2 (GB5009.229), moisture (%) ≤ 0.05 (GB5009.236)

[0052] Soybean oil, COFCO, National Standard Grade 1 soybean oil. Acid value (KOH) ≤ 0.5 (GB5009.229), Moisture (%) ≤ 0.1 (GB5009.236)

[0053] Castor oil, Beijing Innocare Technology. Hydroxyl value 154-170 mg KOH / g, viscosity 650-700 mPa·s, moisture (%) ≤0.1 (GB5009.236)

[0054] Glycerin, Beijing Innocare Technology, AR99%

[0055] Diethylene glycol, Beijing Inokai Technology, 99%

[0056] Dimethylamine, Beijing Inokai Technology, 40% aqueous solution.

[0057] Trimethylamine, Beijing Innocare Technology, 95%.

[0058] N,N-Dimethylcyclohexylamine, Beijing Inokai Technology, 95%

[0059] N-Methylimidazole, Beijing Inokai Technology, 95%

[0060] Experimental equipment:

[0061] 3000ml four-necked flask, heating mantle, stirrer, circulating water vacuum pump, constant pressure dropping funnel. 5L metal reactor, plunger pump.

[0062] Analytical instruments and methods: Hydroxyl value conformed to GB / T 12008.3-2009; viscosity was measured using a BROOKFIELD DV 2T, conforming to GB / T 12008.7-2010; acid value conformed to GB / T 12008.5-2010. Product molecular weight characterization: Instrument - Waters 2414. Detection method: Calibration using polyethylene glycols of different molecular weights. Injection temperature: 35℃. Injection flow rate: 1 ml / min. Injection solvent: tetrahydrofuran.

[0063] Example 1

[0064] 50g of methanol and 3g of a 40% aqueous solution of tetrafluoroboric acid were added to a four-necked flask. Nitrogen was used to purge the mixture, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the epoxidized soybean oil A was added, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum level was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum level was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum level was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product a2.

[0065] The intermediate product a2 polyether polyol obtained had a hydroxyl value of 113 mgKOH / g, a viscosity of 3523 mPa·s at 25℃, an acid value of 0.07 mgKOH / g, and GPC-determined molecular weights of 1070 (58.09%), 1971 (16.46%), and 3043 (25.45%). Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.9. 1000 g of intermediate product a1 polyether polyol was taken, and 400 g of cottonseed oil, 73.6 g of propylene glycol, and 10 g of a 40% wt aqueous solution of dimethylamine catalyst were added. The mixture was purged with nitrogen, heated to 105℃, and 232 g of ethylene oxide was gradually added dropwise. After the addition was complete, the mixture was heated to mature and degas, yielding the finished polyether polyol A2. The hydroxyl value is 131 mg KOH / g, the viscosity at 25℃ is 1745 mPa·s, the acid value is 0.09 mg KOH / g, and the theoretical functionality is 1.2 based on the hydroxyl value and molecular weight.

[0066] Example 2

[0067] 300g of ethanol and 7.5g of 80% wt phosphoric acid aqueous solution were added to a four-necked flask. Nitrogen was used for purging, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the addition of epoxidized soybean oil B was complete, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum degree was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum degree was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum degree was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product a3.

[0068] The obtained epoxidized soybean oil polyether polyol had a hydroxyl value of 81 mgKOH / g, a viscosity of 2786 mPa·s at 25℃, an acid value of 0.07 mgKOH / g, and GPC-determined molecular weights of 1123 (75.26%), 1977 (16.16%), and 2855 (7.98%). Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.3. 1000 g of intermediate product a3 polyether polyol was taken, and 200 g of castor oil, 92.4 g of diethylene glycol, and 6 g of catalyst N,N-dimethylcyclohexylamine were added. The mixture was purged with nitrogen, heated to 105℃, and 432 g of propylene oxide was gradually added dropwise. After the addition was complete, the mixture was heated to mature and degas, yielding the finished polyether polyol A3. The hydroxyl value is 136 mg KOH / g, the viscosity at 25℃ is 2217 mPa·s, the acid value is 0.11 mg KOH / g, and the theoretical functionality is 1.6 based on the hydroxyl value and molecular weight.

[0069] Example 3

[0070] 60g of ethanol and 2.5g of 40% wt aqueous solution of tetrafluoroboric acid were added to a four-necked flask. Nitrogen was used for purging, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil A was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the epoxidized soybean oil was added, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum degree was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum degree was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum degree was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product a4.

[0071] The obtained epoxidized soybean oil polyether polyol had a hydroxyl value of 61 mgKOH / g, a viscosity of 1628 mPa·s at 25℃, an acid value of 0.05 mgKOH / g, and GPC-determined molecular weights of 1110 (47.33%), 2058 (17.47%), and 3243 (35.20%). Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.0. 1000 g of intermediate product a4 polyether polyol was taken, and 300 g of soybean oil, 34 g of diethylene glycol, and 2 g of N-methylimidazolium catalyst were added. The mixture was purged with nitrogen, heated to 100℃, and 232 g of ethylene oxide was gradually added dropwise. After the addition was complete, the mixture was heated to mature and degas, yielding the finished polyether polyol A4. The hydroxyl value is 55 mg KOH / g, the viscosity at 25℃ is 1207 mPa·s, the acid value is 0.09 mg KOH / g, and the theoretical functionality is 1.0 based on the hydroxyl value and molecular weight.

[0072] Comparative Example 1

[0073] Compared with Example 2, the difference is that a non-monofunctional small molecule alcohol is added in the S1 stage.

[0074] 50g of diethylene glycol and 3g of a 40% aqueous solution of tetrafluoroboric acid were added to a four-necked flask. Nitrogen was used for purging, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil A was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the epoxidized soybean oil was added, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum degree was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum degree was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum degree was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product b2.

[0075] The intermediate product b2 polyether polyol obtained had a hydroxyl value of 152 mg KOH / g, a viscosity of 10337 mPa·s at 25℃, an acid value of 0.07 mg KOH / g, and GPC-determined molecular weights of 1163 (25.18%), 1973 (36.56%), and 3115 (38.26%). 1000 g of the intermediate product b2 polyether polyol was mixed with 400 g of cottonseed oil, 73.6 g of propylene glycol, and 10 g of a 40% wt aqueous solution of dimethylamine catalyst. The mixture was purged with nitrogen, heated to 105℃, and 232 g of ethylene oxide was gradually added dropwise. After the addition was complete, the mixture was heated to mature and degas. The finished polyether polyol B2 was obtained. It had a hydroxyl value of 129 mg KOH / g, a viscosity of 4773 mPa·s at 25℃, and an acid value of 0.09 mg KOH / g. Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.4.

[0076] Comparative Example 2

[0077] Compared with Example 3, the difference is that PO is not added in S4.

[0078] 300g of ethanol and 7.5g of 80% wt phosphoric acid aqueous solution were added to a four-necked flask. Nitrogen was used for purging, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil B was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the epoxidized soybean oil was added, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum degree was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum degree was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum degree was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product B3.

[0079] The obtained epoxidized soybean oil polyether polyol b3 had a hydroxyl value of 80 mg KOH / g, a viscosity of 2774 mPa·s at 25℃, an acid value of 0.07 mg KOH / g, and GPC-determined molecular weights of 1131 (74.46%), 1975 (17.33%), and 2903 (8.21%). Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.3. 1000 g of intermediate product b3 polyether polyol was taken, and 203 g of castor oil, 92.4 g of diethylene glycol, and 6 g of N,N-dimethylcyclohexylamine catalyst were added. The mixture was purged with nitrogen, heated to 105℃ to initiate the transesterification reaction, and after completion, it was cured and degassed to obtain the finished polyether polyol B3. The hydroxyl value is 141 mg KOH / g, the viscosity at 25℃ is 1622 mPa·s, the acid value is 0.11 mg KOH / g, and the theoretical functionality is 1.6 based on the hydroxyl value and molecular weight.

[0080] Comparative Example 3

[0081] Compared with Example 3, no small molecule alcohol was added in S4.

[0082] 60g of ethanol and 2.5g of 40% wt aqueous solution of tetrafluoroboric acid were added to a four-necked flask. Nitrogen was used for purging, and stirring was started at 100 rpm. 1000g of epoxidized soybean oil A was added using a constant-pressure dropping funnel at a dropping rate of 500g / h. The condenser system was turned on, and the reaction temperature was controlled at 85℃. After the epoxidized soybean oil was added, stirring and aging continued for 2 hours. After aging, the vacuum system was turned on for degassing. Degassing stage 1: Nitrogen was turned on, and the vacuum degree was controlled at -0.07MPa for 2 hours. Degassing stage 2: Nitrogen was turned on, and the vacuum degree was controlled at -0.09MPa for 2 hours. Degassing stage 3: The nitrogen line was turned off, and the vacuum degree was controlled at -0.097MPa for 2 hours. After degassing, the material was discharged to obtain intermediate product b4.

[0083] The prepared epoxidized soybean oil polyether polyol b4 had a hydroxyl value of 63 mgKOH / g, a viscosity of 1530 mPa·s at 25℃, an acid value of 0.05 mgKOH / g, and GPC-determined molecular weights of 1092 (46.15%), 2033 (17.41%), and 3217 (36.44%). Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 1.0. 1000 g of intermediate product b4 polyether polyol was taken, 304 g of soybean oil was added, and 2 g of N-methylimidazolium catalyst was added. Nitrogen was used for purging, and the temperature was raised to 100℃. 232 g of ethylene oxide was gradually added dropwise. After the addition was complete, the mixture was heated to mature and degas. The finished polyether polyol B4 was obtained. It had a hydroxyl value of 41 mgKOH / g, a viscosity of 1409 mPa·s at 25℃, and an acid value of 0.07 mgKOH / g. Based on the hydroxyl value and molecular weight, the theoretical functionality was calculated to be 0.8.

[0084] A comparison of the examples and comparative examples shows that the viscosity is significantly reduced when using monofunctional small-molecule polyols. In the CASE and flexible foam fields, lower viscosity is significantly beneficial for production. In the S4 stage, omitting PO leads to foam collapse, while omitting small-molecule alcohol leads to product stratification.

[0085] This invention illustrates the detailed process equipment and process flow through the above embodiments. However, this invention is not limited to the detailed process equipment and process flow described above, meaning that this invention does not necessarily depend on the detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method for the preparation of a bio-based polyol, characterized in that, The preparation method includes the following steps: S1: Mix the alcohol with the catalyst; S2: Add epoxidized soybean oil to react; S3: Post-treatment to remove unreacted small molecule alcohols and VOCs; S4: Add epoxides, natural oils and small molecule polyols for reaction and transesterification.

2. The production method according to claim 1, characterized by, The alcohol in S1 is a monofunctional alcohol of C1 to C4, preferably methanol and / or ethanol; And / or, the catalyst in S1 is an acidic catalyst, preferably one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and tetrafluoroboric acid.

3. The preparation method according to claim 1, characterized in that, When epoxidized soybean oil is added to S2, the ratio of alcohol to epoxidized soybean oil is (0.05-0.6):1, preferably (0.05-0.4):1; And / or, the epoxy value of the epoxidized soybean oil added in S2 is 4.0-6.

5.

4. The production method according to claim 1, characterized by, The epoxide in S4 is a C2-C4 epoxide, preferably propylene oxide and / or ethylene oxide; And / or, the small molecule polyol in S4 is a polyol with a C2 to C4 function of 2 to 4, preferably one or more of ethylene glycol, propylene glycol, diethylene glycol, glycerol, and butylene glycol; And / or, the natural oil in S4 is an oil with a triglyceride structure, preferably one or more of palm oil, soybean oil, cottonseed oil, and castor oil; Preferably, the mass ratio of epoxidized soybean oil, natural oil, small molecule polyol, and epoxide in S4 is 1:(0.1-0.6):(0.02-0.1):(0.1-0.5), more preferably 1:(0.2-0.4):(0.03-0.06):(0.2-0.5); And / or, the catalyst in S4 is an amine and / or imidazole, preferably one or more of trimethylamine, dimethylamine, N,N-dimethylcyclohexylamine, and N-methylimidazole; Preferably, the concentration of the catalyst is 2000-10000 ppm, more preferably 4000-6000 ppm; And / or, the temperature in S4 is 90℃~115℃.

5. A bio-based polyol, obtainable by the process according to any one of claims 1 to 4, characterized in that, The raw materials for the bio-based polyol include: epoxidized soybean oil, alcohol, natural oils, polyols, and epoxides; based on the total amount of the above-mentioned polymerized monomers being 100%, the alcohol content used is 5% to 20%.

6. The bio-based polyol according to claim 5, characterized in that, The intermediate bio-based polyol obtained by reacting alcohol with epoxidized soybean oil has a molecular weight of 1000-1200. Its first byproduct has a molecular weight of 1900-2200 and is generated by the ring-opening polymerization of one molecule of hydroxyl-containing epoxidized soybean oil polyether and one molecule of soybean oil derivative containing epoxy groups. The second byproduct has a molecular weight of 2800-3300 and is generated by the ring-opening polymerization of one molecule of the first byproduct and one molecule of soybean oil derivative containing epoxy groups.

7. The bio-based polyol of claim 5, wherein, The bio-based polyol has a functionality of 1–4, a hydroxyl value of 60–170 mgKOH / g, and a viscosity of 500–8000 mPa·s at 25°C.

8. Use of a bio-based polyol, wherein the polyol is prepared by the method of any one of claims 1-4, or is the polyol of any one of claims 5-7, wherein the polyol is used in polyurethane foam, preferably in flexible polyurethane foam.

9. A polyurethane flexible foam article made using the polyol made according to the process of any one of claims 1-4, or the polyol of any one of claims 5-7.

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