Method for catalytically synthesizing sorbitol-based polyether polyol using liquid sorbitol as raw material

Abstract

The present invention belongs to the technical field of polyether polyols, and specifically relates to a method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material. The synthesis method is as follows: firstly, a first part of liquid sorbitol and a first part of alkylene oxide are subjected to a preliminary polymerization reaction under the action of a first part of an alkali metal nitride catalyst to obtain an intermediate; then, a second part of liquid sorbitol and a second part of alkylene oxide are added to the intermediate, and a polymerization reaction is carried out again under the action of a second part of an alkali metal nitride catalyst to obtain a crude sorbitol-based polyether polyol; finally, the crude sorbitol-based polyether polyol is subjected to a refining treatment to obtain a refined sorbitol-based polyether polyol. The present invention realizes the synthesis of sorbitol-based polyether polyols using high-water content liquid sorbitol as an initiator without a dehydration process, and the functionality of the finished polyether polyol is not reduced, and the product performance is excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of polyether polyols, and particularly relates to a method for catalytically synthesizing sorbitol-based polyether polyols by taking liquid sorbitol as a raw material. Background Art

[0002] Sorbitol has a high functionality, and the position of the hydroxyl groups in its molecular chain is basically the same, so the molecular structure of sorbitol-based polyether polyol is more regular, and the related products also have higher strength and dimensional stability. In addition, the composite material prepared with sorbitol-based polyether polyol as the main raw material often has better fluidity, finer pores and lower thermal conductivity during the foaming process.

[0003] Industrial sorbitol is generally divided into two types: solid sorbitol and liquid sorbitol with a water content of about 30wt.%. Compared with liquid sorbitol, solid sorbitol has higher prices, easy clogging of pipelines during large-scale production, difficulty in feeding, slow initiation of reaction, long production cycle and other problems. Although liquid sorbitol does not have the above problems, it contains a large amount of water, which will react with alkylene oxide during the synthesis process of polyether polyols to generate small molecular weight polyols, causing the product hydroxyl value index to increase significantly, and greatly reducing the functionality of the polyether finished product, resulting in poor product performance.

[0004] In order to avoid a large amount of water in liquid sorbitol from participating in the reaction, the solution currently commonly used in the industry is to dehydrate sorbitol. For example, patent CN112708125A discloses a method for preparing sorbitol-based polyether polyols, which uses liquid sorbitol as an initiator to polymerize liquid sorbitol, a catalyst and a portion of epoxides, dehydrates the resulting product to obtain a first intermediate product with a water content of ≤2wt%, and then continues to polymerize with the remaining epoxides to obtain sorbitol-based polyether polyols. However, the dehydration process results in high production energy consumption, a long production cycle, and produces a large amount of wastewater, which greatly increases the manufacturing cost.

[0005] In addition, patent CN113667111A discloses a method for preparing a sorbitol-based high molecular weight polyether polyol, which uses solid sorbitol and oligosorbitol-based polyether polyol as composite initiators, uses alkali metal as catalyst, and performs ring-opening polymerization with epoxy compounds to obtain a sorbitol-based high molecular weight polyether polyol. In this method, solid sorbitol is more expensive than liquid sorbitol, and there are problems such as easy clogging of pipelines and dust pollution during large-scale production. The production operation is extremely inconvenient.

[0006] Therefore, it is necessary to study a suitable method for synthesizing sorbitol-based polyether polyols using high-water content liquid sorbitol as a raw material, so as to solve the problem of product performance degradation caused by water participating in the reaction of liquid sorbitol during the synthesis process. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material, which realizes the synthesis of sorbitol-based polyether polyols using high-water content liquid sorbitol as a starter without a dehydration process, and the functionality of the finished polyether polyol is not reduced, and the product performance is excellent.

[0008] The method for catalytically synthesizing sorbitol-based polyether polyol using liquid sorbitol as a raw material comprises the following steps: firstly subjecting a first portion of liquid sorbitol and a first portion of alkylene oxide to a preliminary polymerization reaction under the action of a first portion of an alkali metal nitride catalyst to obtain an intermediate; then, adding a second portion of liquid sorbitol and a second portion of alkylene oxide to the intermediate, and subjecting the intermediate to a second polymerization reaction under the action of the second portion of an alkali metal nitride catalyst to obtain a crude sorbitol-based polyether polyol; and finally, subjecting the crude sorbitol-based polyether polyol to a refining treatment to obtain a refined sorbitol-based polyether polyol.

[0009] In the present invention, the water content of the liquid sorbitol is 28-32 wt.%.

[0010] In the present invention, the alkylene oxide is one or both of ethylene oxide and propylene oxide.

[0011] In the present invention, the alkali metal nitride catalyst is one or more of sodium nitride, potassium nitride, sodium azide and potassium azide.

[0012] The raw materials used in the present invention are calculated by weight: 1-40 parts of liquid sorbitol, 10-90 parts of alkylene oxide, and 1-15 parts of alkali metal nitride catalyst.

[0013] In the present invention, the first part of liquid sorbitol accounts for 5-30% of the total mass of the liquid sorbitol.

[0014] In the present invention, the first part of alkylene oxide accounts for 70-90% of the total mass of alkylene oxide.

[0015] In the present invention, the mass of the first part of the alkali metal nitride catalyst accounts for 7-45% of the total mass of the alkali metal nitride catalyst.

[0016] In the present invention, the initial polymerization reaction temperature is 70-90° C., and the reaction time is 60-300 min; the secondary polymerization reaction temperature is 100-120° C., and the reaction time is 60-300 min.

[0017] In the present invention, the refining process is: firstly, phosphoric acid is added to the crude sorbitol-based polyether polyol for neutralization treatment, then an adsorbent is added for adsorption treatment, and finally, dehydration and drying, reduced pressure filtration and extraction are performed to obtain the refined sorbitol-based polyether polyol.

[0018] Preferably, during the neutralization treatment, the amount of phosphoric acid added is 1.5-3.5 times the total mass of the alkali metal nitride; the neutralization treatment temperature is 80-90° C., and the time is 0.5-1 h.

[0019] Preferably, during the adsorption treatment, the adsorbent used is a conventional adsorbent, such as magnesium silicate, aluminum silicate, magnesium aluminum silicate, etc., and the amount of the adsorbent added is 0.05-0.1% of the mass of the crude sorbitol-based polyether polyol; the adsorption treatment temperature is 80-90°C, and the time is 0.5-1h.

[0020] In one embodiment, the method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material comprises the following steps:

[0021] (1) adding the first part of liquid sorbitol and the first part of alkali metal nitride catalyst into a reactor, pumping the pressure of the reactor to below -0.09 MPa after nitrogen replacement, stirring and heating to 70-90° C., slowly introducing the first part of alkylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 60-300 minutes until the pressure of the reactor no longer decreases, thereby obtaining an intermediate product;

[0022] (2) adding a second portion of liquid sorbitol and a second portion of an alkali metal nitride catalyst to the intermediate product, pumping the pressure of the reactor to below -0.09 MPa after nitrogen substitution, heating the reactor to 100-120° C. with stirring, and then slowly introducing the second portion of alkylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 60-300 minutes until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0023] (3) Phosphoric acid is added to the crude sorbitol-based polyether polyol for neutralization treatment, and then an adsorbent is added for adsorption treatment, and finally dehydration, drying, and vacuum filtration are performed to obtain a refined sorbitol-based polyether polyol.

[0024] In order to avoid water participating in the reaction and causing the functionality of the polyether polyol to be reduced, the present invention realizes the synthesis of high-functionality sorbitol-based polyether polyol. Firstly, an alkali metal nitride is used as a catalyst, and a large amount of water can be consumed by the reaction of the alkali metal nitride with water. At the same time, the product generates an alkali metal hydroxide, which catalyzes the subsequent polymerization reaction of sorbitol and alkylene oxide. Secondly, an alkaline catalyst excess process is adopted to make the reaction system present an alkaline environment, thereby inhibiting the reaction activity of water and alkylene oxide. Thirdly, a small amount of liquid sorbitol is used to pre-connect a large amount of alkylene oxide at low temperature, and the remaining large amount of liquid sorbitol is polymerized with a small amount of alkylene oxide, thereby reducing the possibility of large-scale and long-term direct contact between water and alkylene oxide.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention uses alkali metal nitride as a catalyst system and optimizes the reaction process to achieve the synthesis of sorbitol-based polyether polyols without dehydration process using high-water content liquid sorbitol as an initiator, and the functionality of the finished polyether polyol is not reduced, and the product performance is excellent;

[0027] (2) The present invention does not require dehydration of liquid sorbitol with a high water content. Compared with the traditional dehydration process, it has the advantages of low energy consumption and short production cycle, while reducing the generation of wastewater, saving energy and being environmentally friendly. DETAILED DESCRIPTION

[0028] The present invention is further described below with reference to the examples. The raw materials used in the examples, unless otherwise specified, are all commercially available conventional raw materials; the process methods used in the examples, unless otherwise specified, are all conventional methods in the art.

[0029] In actual operation, the temperature control allows a temperature fluctuation of 2°C.

[0030] Example 1

[0031] Sorbitol-based polyether polyols were synthesized as follows:

[0032] (1) Add 30 g of liquid sorbitol (water content 30 wt.%) and 13.5 g of sodium nitride to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 70° C., slowly introduce 240 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0033] (2) adding 70 g of liquid sorbitol (water content 30 wt.%) and 31.5 g of sodium nitride to the intermediate product, pumping the pressure of the reactor to -0.09 MPa after nitrogen replacement, heating to 100° C. with stirring, and then slowly introducing 31 g of propylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 180 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0034] (3) To the crude sorbitol-based polyether polyol, 45 g of 70 wt.% phosphoric acid was added, and the mixture was stirred at 80° C. for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80° C. for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0035] Example 2

[0036] Sorbitol-based polyether polyols were synthesized as follows:

[0037] (1) Add 10 g of liquid sorbitol (water content 32 wt.%) and 5 g of potassium nitride to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 90° C., slowly introduce 230 g of ethylene oxide into the reactor, keep the temperature stable, and continue the reaction for 300 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0038] (2) adding 90 g of liquid sorbitol (water content 32 wt.%) and 20 g of potassium nitride to the intermediate product, pumping the pressure of the reactor to -0.09 MPa after nitrogen replacement, stirring and heating to 120° C., then slowly introducing 33 g of ethylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 60 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0039] (3) Add 50 g of 70 wt.% phosphoric acid to the crude sorbitol-based polyether polyol, stir at 90° C. for 1 h, then add an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate, stir at 90° C. for 0.5 h, dehydrate and dry, and filter under reduced pressure to obtain refined sorbitol-based polyether polyol.

[0040] Example 3

[0041] Sorbitol-based polyether polyols were synthesized as follows:

[0042] (1) Add 20 g of liquid sorbitol (water content 28 wt.%) and 20 g of sodium azide to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 80° C., slowly introduce 220 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 150 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0043] (2) adding 80 g of liquid sorbitol (water content 28 wt.%) and 25 g of sodium azide to the intermediate product, evacuating the pressure of the reactor to -0.09 MPa after nitrogen replacement, stirring and heating to 110° C., and then slowly introducing 60 g of ethylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 100 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0044] (3) Add 80 g of 70 wt.% phosphoric acid to the crude sorbitol-based polyether polyol, stir at 80° C. for 1 h, then add an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate, stir at 80° C. for 1 h, dehydrate and dry, and filter under reduced pressure to obtain refined sorbitol-based polyether polyol.

[0045] Example 4

[0046] Sorbitol-based polyether polyols were synthesized as follows:

[0047] (1) Add 30 g of liquid sorbitol (water content 30 wt.%) and 2 g of potassium azide to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 90° C., slowly introduce 200 g of ethylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0048] (2) adding 70 g of liquid sorbitol (water content 30 wt.%) and 28 g of potassium azide to the intermediate product, evacuating the pressure of the reactor to -0.09 MPa after nitrogen replacement, heating the reactor to 110° C. with stirring, and then slowly introducing 71 g of propylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 210 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0049] (3) Refining treatment: 45 g of 70 wt.% phosphoric acid was added to the crude sorbitol-based polyether polyol, and the mixture was stirred at 80°C for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80°C for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0050] Comparative Example 1

[0051] Sorbitol-based polyether polyols were synthesized as follows:

[0052] (1) 100 g of liquid sorbitol (water content 30 wt.%) and 3 g of potassium hydroxide were added to a 1 L reactor in sequence, and the pressure of the reactor was reduced to -0.09 MPa after nitrogen replacement. The temperature was raised to 100° C. with stirring, and 271 g of propylene oxide was slowly introduced. The reaction was carried out at 100° C. for 120 min until the pressure of the reactor stopped decreasing, thereby obtaining a crude sorbitol-based polyether polyol;

[0053] (2) Add 5 g of 70 wt.% phosphoric acid to the crude sorbitol-based polyether polyol, stir at 80°C for 1 h, then add an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate, stir at 100°C for 1 h, dehydrate and dry, and filter under reduced pressure to obtain refined sorbitol-based polyether polyol.

[0054] Comparative Example 2

[0055] Sorbitol-based polyether polyols were synthesized as follows:

[0056] (1) Add 30 g of liquid sorbitol (water content 30 wt.%) and 13.5 g of sodium nitride to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 70° C., slowly introduce 40 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0057] (2) adding 70 g of liquid sorbitol (water content 30 wt.%) and 31.5 g of sodium nitride to the intermediate product, pumping the pressure of the reactor to -0.09 MPa after nitrogen replacement, heating to 100° C. with stirring, and then slowly introducing 231 g of propylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 180 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0058] (3) To the crude sorbitol-based polyether polyol, 45 g of 70 wt.% phosphoric acid was added, and the mixture was stirred at 80° C. for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80° C. for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0059] Comparative Example 3

[0060] Sorbitol-based polyether polyols were synthesized as follows:

[0061] (1) Add 30 g of liquid sorbitol (water content 30 wt.%) and 13.5 g of potassium hydroxide to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 70° C., slowly introduce 240 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0062] (2) adding 70 g of liquid sorbitol (water content 30 wt.%) and 31.5 g of potassium hydroxide to the intermediate product, evacuating the pressure of the reactor to -0.09 MPa after nitrogen replacement, heating the reactor to 100° C. with stirring, and then slowly introducing 31 g of propylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 180 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0063] (3) To the crude sorbitol-based polyether polyol, 45 g of 70 wt.% phosphoric acid was added, and the mixture was stirred at 80° C. for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80° C. for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0064] Comparative Example 4

[0065] Sorbitol-based polyether polyols were synthesized as follows:

[0066] (1) Add 30 g of liquid sorbitol (water content 30 wt.%) and 2.5 g of sodium nitride to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 70° C., slowly introduce 240 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0067] (2) adding 70 g of liquid sorbitol (water content 30 wt.%) and 2.5 g of sodium nitride to the intermediate product, pumping the pressure of the reactor to -0.09 MPa after nitrogen replacement, heating to 100° C. with stirring, and then slowly introducing 31 g of propylene oxide into the reactor, keeping the temperature stable, and continuing the reaction for 180 min until the pressure of the reactor no longer decreases, thereby obtaining a crude sorbitol-based polyether polyol;

[0068] (3) To the crude sorbitol-based polyether polyol, 45 g of 70 wt.% phosphoric acid was added, and the mixture was stirred at 80° C. for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80° C. for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0069] Comparative Example 5

[0070] Sorbitol-based polyether polyols were synthesized as follows:

[0071] (1) Add 100 g of liquid sorbitol (water content 30 wt.%) and 45 g of sodium nitride to a 1 L reactor, pump the reactor pressure to -0.09 MPa after nitrogen replacement, stir and heat to 70° C., slowly introduce 100 g of propylene oxide into the reactor, keep the temperature stable, and continue the reaction for 120 min until the reactor pressure no longer decreases, to obtain an intermediate product;

[0072] (2) The reactor was heated to 105° C. and the pressure was evacuated to −0.09 MPa. Nitrogen was bubbled into the reactor from the bottom of the reactor to maintain the pressure at −0.08 MPa for 3 h. After the dehydration was completed, 171 g of propylene oxide was slowly introduced into the reactor. The temperature was kept stable and the reaction was continued for 180 min until the pressure in the reactor stopped decreasing, thereby obtaining a crude sorbitol-based polyether polyol.

[0073] (3) To the crude sorbitol-based polyether polyol, 45 g of 70 wt.% phosphoric acid was added, and the mixture was stirred at 80° C. for 0.5 h. Then, an adsorbent consisting of 0.4 g of magnesium silicate and 0.2 g of aluminum silicate was added. The mixture was stirred at 80° C. for 1 h, and then dehydrated, dried, and filtered under reduced pressure to obtain a refined sorbitol-based polyether polyol.

[0074] The sorbitol-based polyether polyols synthesized in the examples and comparative examples were tested for performance indicators, wherein the hydroxyl value was tested with reference to the standard GB / T 12008.3-1989, and the viscosity was tested with reference to the standard GB / T 12008.7-2010. The test results are shown in Table 1.

[0075] Table 1 Performance indexes of sorbitol-based polyether polyols

[0076]

[0077]

[0078] The sorbitol-based polyether polyols synthesized in the examples and comparative examples were formulated according to the formula shown in Table 2 to obtain composite polyethers, wherein:

[0079] INOVOL R6207 is a polyether polyol produced by Shandong INOVOL New Materials Co., Ltd.

[0080] H 2 O is a chemical foaming agent;

[0081] N,N-dimethylcyclohexylamine as catalyst;

[0082] TMR-2 is the catalyst, produced by Xindian Chemical Materials (Shanghai) Co., Ltd.;

[0083] BDMA (N,N-dimethylbenzylamine) is the catalyst;

[0084] Cyclopentane is a physical foaming agent;

[0085] TEGOSTAB B8460 is a silicone oil produced by Evonik Specialty Chemicals (Shanghai) Co., Ltd.

[0086] Table 2 Rigid polyurethane foam sample formula

[0087] raw material Weight Sorbitol based polyether polyol 70 INOVOL R6207 30 <![CDATA[H 2 The]]> 1.5 N,N-Dimethylcyclohexylamine 1 TMR-2 0.5 BDMA 0.3 Cyclopentane 20 TEGOSTAB B8460 2

[0088] The above-mentioned combined polyether was mixed with isocyanate PM200 (Wanhua Chemical Group Co., Ltd.) to prepare a rigid polyurethane foam sample as follows:

[0089] Under the conditions of ambient temperature of 25°C and mold temperature of 45°C, the materials were accurately weighed according to the formula in Table 2, and prepared into a combined polyether in a 500mL beaker. 50 parts by weight of the combined polyether and 60 parts of isocyanate PM200 were fully stirred. When the system was uniform, stirring was stopped, and the stirred materials were poured into a constant temperature foaming molding mold. After the foam was foamed, matured and cured, it was taken out of the mold to obtain a polyurethane rigid foam sample.

[0090] The performance of the polyurethane rigid foam samples was tested, among which the compression strength was tested according to the standard GB / T 8813-2008, and the sample size was 5cm×5cm×5cm; the dimensional stability was tested by placing the sample block with the size of 10cm×10cm×2.5cm at 80℃ and -30℃ for 48h, and then measuring the foam shrinkage. The test results are shown in Table 3.

[0091] Table 3 Performance test results of rigid polyurethane foam samples

[0092]

[0093] As can be seen from Table 3, Comparative Example 1 adopts a one-step synthesis process, Comparative Example 2 is not the process of pre-connecting a small amount of liquid sorbitol with a large amount of alkylene oxide in the present invention, Comparative Example 3 is not the alkali metal nitride catalysis process in the present invention, Comparative Example 4 is not the alkaline catalyst excess process, and Comparative Example 5 adopts a conventional dehydration process.

[0094] Compared with Example 1, Comparative Example 5 has a production cycle increased by 3 hours due to the presence of a dehydration process, which inevitably leads to increased energy consumption and wastewater discharge.

[0095] Compared with Comparative Examples 1-5, the actual hydroxyl value of the sorbitol-based polyether polyol of Examples 1-4 is basically consistent with the designed hydroxyl value, and the viscosity index is basically in line with expectations, indicating that there is no large amount of water participating in the reaction to cause a significant increase in the hydroxyl value index; the rigid polyurethane foam samples prepared therefrom have significantly better compressive strength performance, and higher dimensional stability at high and low temperatures, indicating that there is no large amount of water participating in the reaction to cause a decrease in functionality and loss of product performance.

Claims

1. A method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material, characterized in that: First, a first portion of liquid sorbitol and a first portion of alkylene oxide are subjected to a preliminary polymerization reaction under the action of a first portion of alkali metal nitride catalyst to obtain an intermediate; a second portion of liquid sorbitol and a second portion of alkylene oxide are added to the intermediate, and a second polymerization reaction is carried out under the action of the second portion of alkali metal nitride catalyst to obtain a crude sorbitol-based polyether polyol; and finally, the crude sorbitol-based polyether polyol is subjected to a refining treatment to obtain a refined sorbitol-based polyether polyol; in: The water content of liquid sorbitol is 28-32wt.%; The alkali metal nitride catalyst is one or more of sodium nitride, potassium nitride, sodium azide, and potassium azide; The raw materials are calculated by weight: 1-40 parts of liquid sorbitol, 10-90 parts of alkylene oxide, and 1-15 parts of alkali metal nitride catalyst; The first part of liquid sorbitol accounts for 5-30% of the total mass of the liquid sorbitol; The first part of alkylene oxide accounts for 70-90% of the total mass of alkylene oxide; The mass of the first part of the alkali metal nitride catalyst accounts for 7-45% of the total mass of the alkali metal nitride catalyst.

2. The method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material according to claim 1, characterized in that: The alkylene oxide is one or both of ethylene oxide and propylene oxide.

3. The method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material according to claim 1, characterized in that: The initial polymerization reaction temperature is 70-90°C, and the reaction time is 60-300min; the secondary polymerization reaction temperature is 100-120°C, and the reaction time is 60-300min.

4. The method for catalytically synthesizing sorbitol-based polyether polyols using liquid sorbitol as a raw material according to claim 1, characterized in that: The refining process is as follows: firstly, phosphoric acid is added to the crude sorbitol-based polyether polyol for neutralization treatment, then an adsorbent is added for adsorption treatment, and finally, dehydration and drying and vacuum filtration are performed to obtain refined sorbitol-based polyether polyol.

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