Preparation method of low-odor polyether polyol

Abstract

The invention relates to a preparation method of low-odor polyether polyol, which comprises the following steps: 1) mixing a potassium alkoxide initiator with inorganic phosphazene salt, and generating phosphazene salt which has catalytic activity and is combined with initiator anions and sylvite without catalytic activity at 50-120 DEG C; 2) in the presence of the product in the step 1), carrying out ring opening polymerization on alkylene oxide to obtain polyether polyol; and 3) filtering the product in the step 2) to remove potassium salt, inorganic acid and water for neutralization, removing water in polyether at high temperature, and filtering to obtain inorganic phosphazene salt and polyether polyol products. The inorganic phosphazene salt can be co-catalyzed with the potassium alkoxide initiator again to synthesize the polyether polyol. The inorganic phosphazene catalyst used in the method is good in stability, the prepared polyether polyol is extremely low in odor, meanwhile, the recovery rate of the phosphazene catalyst can reach 95% or above, and the problems that in an existing process for preparing polyether through the phosphazene catalyst, the product odor is large, and the cost is high are solved.

Description

Technical Field

[0001] The invention belongs to the field of polyether polyol synthesis, and particularly relates to a method for preparing low-odor polyether polyol by phosphazene catalysis and recycling the catalyst. Background Art

[0002] Polyether polyols are important chemical raw materials and are widely used in the fields of foam products, elastomers, sealants, coatings, adhesives, leather products, lubricants, automotive brake fluids, metal processing and textiles. The preparation methods of polyether polyols mainly include cationic polymerization, anionic polymerization and coordination polymerization. The catalysts for cationic polymerization mainly include protonic acids and Lweis acids. A large amount of by-products such as dioxane will be generated during the polymerization process, which requires relatively cumbersome steps to remove, and are basically not used in industry. The catalyst used in anionic polymerization is mainly KOH, which has the advantages of mild reaction conditions, low catalyst cost, and easy removal in polyether. Therefore, it has been widely used in industry. However, KOH is easy to cause propylene oxide to undergo isomerization reaction during the reaction process to generate polyethers with unsaturated double bonds at the end group, resulting in high unsaturation of the product, which seriously affects downstream applications. The catalysts that have been industrialized for coordination polymerization are mainly double metal cyanide complex catalysts, which have extremely high catalytic activity. The synthesized polyether polyols have the advantages of low unsaturation, high relative molecular weight, and narrow distribution. However, double metal cyanide complex catalysts also have problems such as inability to use small molecule initiators, inability to be used for EO end-capping, and high product viscosity.

[0003] The catalytic mechanism of phosphazene catalyst belongs to anionic polymerization. Due to its large molecular size, delocalized cations, single active point and very strong alkalinity, the catalytically synthesized polyether has the advantages of low unsaturation and high activity. However, there are some problems in the application of existing phosphazene catalysts. First, the storage stability of phosphazene catalysts is poor. They are easy to decompose and deactivate during storage. Generally, the catalytic activity will drop by more than 80% after storage for about one month. Second, phosphazene catalysts are more unstable at high temperatures. When synthesizing polyether polyols, some phosphazenes will decompose to form amine substances with a strong odor, which are also difficult to remove in the refining stage. Third, the molecular weight of phosphazene catalysts is large. When catalyzing small molecule initiators such as ethylene glycol and glycerol, the catalytic activity will drop significantly, resulting in a decrease in production efficiency. When using small molecule polyether polyols as initiators, potassium ions in polyether polyols must be removed, and the steps are cumbersome. Fourth, phosphazene catalysts are expensive and have high use costs. This is a key factor that makes phosphazene catalysts difficult to be widely used in industry.

[0004] CN102171272B discloses a catalyst for the manufacture of polyalkylene glycol and a method for manufacturing polyalkylene glycol using the same. The patent uses an organic phosphazene catalyst to synthesize polyalkylene glycol, and the product does not contain metal components and has no odor residue. However, the patent does not measure the odor level of the product, nor does it explain how to ensure that the organic phosphazene catalyst will not decompose and leave ammonia odor in the product when using an organic phosphazene catalyst with poor thermal stability to synthesize polyalkylene glycol. At the same time, the patent CN111801337B discloses a divalent phosphazene salt and a polyalkylene oxide composition containing it, and a polyurethane forming composition containing the polyalkylene oxide composition, which can provide a polyurethane forming composition that helps to form a polyurethane with suppressed odor and turbidity. However, this method requires the use of a large amount of organic sulfonic acid to neutralize the polyether during the refining of the polyether, resulting in an increase in the production cost of the polyether, and making the polyether process more complicated. At the same time, the catalyst is completely left in the polyether and is not removed. It is unknown whether the product will release odor and VOC when stored for a long time.

[0005] JP3739175B2 discloses a method of synthesizing polyether polyols by catalysis of phosphazene, neutralizing with acid, and adding water to catalytically recover the phosphazene catalyst. This recovery process is complicated, and the recovered phosphazene catalyst needs to be subjected to complex treatment to restore its catalytic activity. In addition, there are problems of low catalyst recovery rate and decreased catalytic activity. Summary of the invention

[0006] To solve the above problems, the present invention provides a method for preparing low-odor polyether polyols by phosphazene catalysis and recycling the catalyst, wherein potassium alcohol is used as an initiator, and reacts with an inorganic phosphazene catalyst to generate a phosphazene salt combined with an initiator anion having catalytic activity, and the catalytically synthesized polyether polyol has extremely low odor, and the inorganic phosphazene catalyst can be recovered after neutralization with an inorganic acid and dehydration and filtration, and can be directly used again for catalytic preparation of polyether polyols without any treatment. In addition, compared with organic phosphazene catalysts, inorganic phosphazene catalysts have better storage stability and can be stably stored for more than one year without affecting the catalytic activity.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a low-odor polyether polyol comprises the following steps:

[0009] 1) mixing a potassium alcohol initiator with an inorganic phosphazene salt to generate a phosphazene salt with catalytic activity combined with an anion of the initiator and a potassium salt without catalytic activity at 50-120° C.;

[0010] 2) in the presence of the product of step 1), ring-opening polymerization of alkylene oxide to form polyether polyol;

[0011] 3) Filtration Step 2) The product is freed from potassium salt, neutralized with inorganic acid and water, and the water in the polyether is removed at high temperature, and the inorganic phosphazene salt and polyether polyol product are obtained by filtration.

[0012] As a preferred solution, the inorganic phosphazene salt obtained in step 3) can be used to repeat steps 1) to 3) with a potassium alcohol initiator to synthesize a polyether polyol.

[0013] In a specific embodiment, the inorganic phosphazene salt has the structural formula [R2N]2C=N]4P + X, wherein R is an alkyl group of 1 to 10 carbon atoms or an aryl group of 6 to 10 carbon atoms, suitable examples include but are not limited to methyl, ethyl, propyl, benzyl, etc., and X is one of Cl-, Br-, I-, H2PO4-, HSO4-, BF4-, etc.

[0014] In a specific embodiment, the potassium alcohol initiator is a product in which the hydrogen on a hydroxyl group of an alcohol compound is replaced by potassium, and the structural formula is as follows:

[0015] YO - K +

[0016] Wherein Y is a polyol having 2 to 10 carbon atoms and containing 1 to 5 hydroxyl groups, or a polyoxyalkylene polyol having 1 to 5 hydroxyl groups and a molecular weight of 500 to 5000. Suitable examples include but are not limited to ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, pentaerythritol, sorbitol, and the like.

[0017] In a specific embodiment, the molar ratio of potassium ions to inorganic phosphazene salt in the potassium alcoholate initiator is 1:1 to 10:1, preferably 1.1:1 to 3:1.

[0018] In a specific embodiment, the alkylene oxide comprises one or more of ethylene oxide, propylene oxide, 1,2-butylene oxide, and the like.

[0019] In a specific embodiment, in step 2), the polymerization reaction temperature is 60 to 160° C., preferably 90 to 110° C., and the reaction pressure is -0.09 to 5 MPa, preferably 0 to 0.5 MPa.

[0020] In a specific embodiment, in step 3), the inorganic acid is one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, sulfuric acid, tetrafluoroboric acid, and the like.

[0021] In a specific embodiment, the molar ratio of the inorganic acid to the inorganic phosphazene salt is 0.5 to 3, preferably 0.9 to 1.5.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1) The present invention uses potassium alcohol initiator and inorganic phosphazene as catalyst to jointly catalyze the synthesis of polyether polyols, thereby solving the problem of strong odor in existing low-unsaturation, high-activity polyethers;

[0024] 2) Compared with the organic phosphazene catalyst, the inorganic phosphazene catalyst used in the present invention has good storage stability and can be stably stored for one year without affecting the catalytic activity;

[0025] 3) The present invention can use a polyether polyol containing potassium ions as an initiator, thereby eliminating the process of removing potassium ions;

[0026] 4) The recovery rate of the inorganic phosphazene catalyst of the present invention can reach more than 95%, which solves the problem of high price and high use cost of phosphazene. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0028] The chemical reagents used in the examples are all commercially available reagents and are of analytical grade.

[0029] Odor test method for polyether polyols: 100 mL of polyether polyol is put into a 200 mL glass bottle and placed in an 80°C oven for 2 hours. After taking it out, more than 5 people smell the polyether polyol and give an odor evaluation. The average of each person's evaluation is taken as the final result.

[0030] The odor evaluation criteria are as follows:

[0031] Table 1

[0032]

[0033]

[0034] Example 1

[0035] 20g glycerol and 0.123g KOH were added to the reaction kettle, and the water in the kettle was removed by a vacuum pump. The temperature was kept at 100°C for 1 hour to obtain potassium glycerol alcohol. 1.04g [(CH3)2N]2C=N]4P was added to the kettle. + Cl - After sufficient nitrogen replacement, the reaction was carried out at 100°C for 1 hour. 867 g of propylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual propylene oxide was removed by vacuum. 157 g of ethylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual ethylene oxide was removed by vacuum.

[0036] After the reaction, potassium chloride in the polyether was removed by filtration, 0.22 g of hydrochloric acid (36.5 wt%) and 50 g of water were added, the temperature was raised to 80°C for neutralization for 1 h, and the water in the polyether was removed by vacuum at 110°C. When the water content was less than 500 ppm, 1.01 g of [R2N]2C=N]4P was recovered by filtration. + Cl - The recovery rate of phosphazene catalyst was 96.79%. The hydroxyl value of the refined polyether polyol was 34.8 mgKOH / g, the unsaturation was 0.02 mmol / g, and the product odor grade was 1.

[0037] Example 2

[0038] 16g of ethylene glycol and 0.148g of KOH were added to the reaction kettle, and the water in the kettle was removed by a vacuum pump. The temperature was kept at 100°C for 1 hour to obtain potassium ethylene glycol. 1.03g of [(CH3)2N]2C=N]4P was added to the kettle. + H2PO4 - After sufficient nitrogen replacement, the reaction was carried out at 50°C for 3 hours. 841 g of propylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual propylene oxide was removed by vacuum. 175 g of ethylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual ethylene oxide was removed by vacuum.

[0039] After the reaction, potassium dihydrogen phosphate in the polyether was removed by filtration, 0.305 g of phosphoric acid (85 wt%) and 50 g of water were added, the temperature was raised to 80°C for neutralization for 1 h, and the moisture in the polyether was removed by vacuum at 110°C. When the moisture was less than 500 ppm, 1.02 g of [R2N]2C=N]4P was recovered by filtration. + H2PO4 - The recovery rate of phosphazene catalyst was 98.81%. The hydroxyl value of the refined polyether polyol was 28.1 mgKOH / g, the unsaturation was 0.019 mmol / g, and the product odor grade was 1.5.

[0040] Example 3

[0041] 100 g of polyoxypropylene triol with a number average molecular weight of 500 was added to the reaction kettle, and the potassium ion concentration was 0.19 wt %. 1.4 g of [(CH3)2N]2C=N]4P was added to the kettle. + BF4 -- After sufficient nitrogen replacement, the reaction was carried out at 120°C for 0.5h. 1160g of propylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual propylene oxide was removed by vacuum. 140g of ethylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual ethylene oxide was removed by vacuum.

[0042] After the reaction, potassium tetrafluoroborate in the polyether was filtered out, 0.74 g tetrafluoroboric acid (50 wt%) and 50 g water were added, the temperature was raised to 80 ° C for 1 h, and the water in the polyether was removed under vacuum at 110 ° C. When the water content was less than 500 ppm, 1.35 g [R2N]2C=N]4P was recovered after filtration. + BF4 - The recovery rate of phosphazene catalyst was 96.43%. The hydroxyl value of the refined polyether polyol was 23.9 mgKOH / g, the unsaturation was 0.022 mmol / g, and the product odor grade was 2.

[0043] Example 4

[0044] 150 g of polyoxypropylene triol with a number average molecular weight of 3000 was added to the reaction kettle, and the potassium ion concentration was 0.2 wt%. 1 g of [(CH3)2N]2C=N]4P was added to the kettle. + HSO4 - After sufficient nitrogen replacement, the reaction was carried out at 80°C for 2h. 700g of propylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual propylene oxide was removed by vacuum. 150g of ethylene oxide was continuously introduced into the reactor, and the reaction was continued until the pressure in the reactor remained constant, and the residual ethylene oxide was removed by vacuum.

[0045] After the reaction, potassium hydrogen sulfate in the polyether was filtered out, 0.15 g sulfuric acid (98 wt%) and 50 g water were added, the temperature was raised to 80°C for neutralization for 1 h, and the water in the polyether was removed under vacuum at 110°C. When the water content was less than 500 ppm, 0.961 g [R2N]2C=N]4P was recovered by filtration. + BF4 - The recovery rate of phosphazene catalyst was 96.1%. The hydroxyl value of the refined polyether polyol was 8.5 mgKOH / g, the unsaturation was 0.025 mmol / g, and the product odor grade was 1.5.

[0046] Comparative Example 1

[0047] 20g glycerol and 1.04g [(CH3)2N]2C=N]4P + CH3O - Add to the reactor, use a vacuum pump to remove the water in the kettle, continue at 100 ° C for 1h, after sufficient nitrogen replacement, continue to pass 867g of propylene oxide into the reactor, continue to react until the pressure in the kettle remains unchanged, and then vacuum remove the residual propylene oxide. Continue to pass 157g of ethylene oxide into the reactor, continue to react until the pressure in the kettle remains unchanged, and then vacuum remove the residual ethylene oxide. After the reaction is completed, use phosphoric acid to neutralize, add magnesium silicate adsorbent, dehydrate and filter to obtain refined polyether polyols. The product hydroxyl value is 35.2mgKOH / g, the unsaturation is 0.028mmol / g, and the product odor level is 4.

[0048] Example 5

[0049] Preparation of initiator-phosphazene

[0050] 20g glycerol and 0.123g KOH were added to the reaction kettle, and the water in the kettle was removed by a vacuum pump. The temperature was kept at 100°C for 1 hour to obtain potassium glycerol alcohol. 1g [(CH3)2N]2C=N]4P was added to the kettle. + Cl-, react at 100℃ for 1h.

[0051] Continue to introduce propylene oxide into the reactor, maintain the pressure in the reactor at 0.2 MPa, and record the time required to introduce 500 g of propylene oxide into the reactor as t. The catalyst reaction activity is 500 / t gPO / g catalyst / h. See Table 2.

[0052] Comparative Example 2

[0053] 20g glycerol and 1.04g [(CH3)2N]2C=N]4P + CH3O - Add to the reaction kettle, use a vacuum pump to remove the moisture in the kettle, and continue at 100°C for 1 hour.

[0054] Continue to introduce propylene oxide into the reactor, maintain the pressure in the reactor at 0.2 MPa, and record the time required to introduce 500 g of propylene oxide into the reactor as t. The catalyst reaction activity is 500 / t gPO / g catalyst / h. See Table 2.

[0055] Comparison of storage stability of inorganic phosphazene salts and organic phosphazene salts, testing of inorganic phosphazene salt [(CH3)2N]2C=N]4P + Cl - With organic phosphazene salt [(CH3)2N]2C=N]4P + CH3O - After the catalytic activity of the two samples was tested, the two samples were stored in a nitrogen environment for 1 year and the catalytic activity of the two samples was further tested. The catalytic activities of the inorganic phosphazene salt and the organic phosphazene salt are shown in Table 2 below:

[0056] Table 2

[0057]

Claims

1. A method for preparing a low-odor polyether polyol, comprising the following steps: 1) mixing a potassium alcohol initiator with an inorganic phosphazene salt to generate a phosphazene salt with catalytic activity combined with an anion of the initiator and a potassium salt without catalytic activity at 50-120° C.; 2) in the presence of the product of step 1), ring-opening polymerization of alkylene oxide to form polyether polyol; 3) Filtration Step 2) The product is freed from potassium salt, neutralized with inorganic acid and water, and the water in the polyether is removed at high temperature, and the inorganic phosphazene salt and polyether polyol product are obtained by filtration.

2. The method according to claim 1, characterized in that The structural formula of the inorganic phosphazene salt is [R2N]2C=N]4P + X, wherein R is an alkyl group of 1 to 10 carbon atoms or an aryl group of 6 to 10 carbon atoms, preferably one or more of methyl, ethyl, propyl, and benzyl, and X is Cl-, Br - 、I-、H2PO4 - 、HSO4 - 、BF4 - One or more of.

3. The method according to claim 1 or 2, characterized in that: The potassium alcohol initiator structural formula is as follows: - K + Wherein Y is a polyol residue having 2 to 10 carbon atoms and containing 1 to 5 hydroxyl groups, or a polyoxyalkylene polyol residue having a hydroxyl functionality of 1 to 5 and a number average molecular weight of 500 to 5000, preferably a residue of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, pentaerythritol, or sorbitol.

4. The method according to any one of claims 1 to 3, characterized in that: The molar ratio of potassium ions to inorganic phosphazene salt in the potassium alcoholate initiator is 1:1 to 10:1, preferably 1.1:1 to 3:

1.

5. The method according to any one of claims 1 to 4, characterized in that: The alkylene oxide includes one or more of ethylene oxide, propylene oxide, and 1,2-butylene oxide.

6. The method according to any one of claims 1 to 5, characterized in that: In the step 2), the polymerization reaction temperature is 60 to 160° C., preferably 90 to 110° C., and the reaction pressure is -0.09 to 5 MPa, preferably 0 to 0.5 MPa.

7. The method according to any one of claims 1 to 6, characterized in that: In the step 3), the inorganic acid is one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, sulfuric acid, and tetrafluoroboric acid.

8. The method according to any one of claims 1 to 7, characterized in that: The molar ratio of the inorganic acid to the inorganic phosphazene salt is 0.5 to 3, preferably 0.9 to 1.5.

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