Synthetic method of propylene glycol polyether

Abstract

The invention belongs to the technical field of polyether polyol preparation, and discloses a synthesis method of propylene glycol polyether. The synthesis method comprises the following steps: mixing propylene glycol, an organic boron catalyst and a cocatalyst, then introducing alkylene oxide at 10-80 DEG C for reaction, adding a solvent into a reaction system after the reaction is finished, and carrying out reduced pressure distillation, washing and drying to obtain propylene glycol polyether, the cocatalyst is selected from one or a combination of at least two of trimethylphosphine, triethylphosphine, triphenylphosphine, tris (dimethylamino) phosphine and tripyrrolidine phosphine. According to the invention, the organic boron catalyst and the cocatalyst phosphine salt are matched for use, and the cocatalyst is selected, so that the reaction can be carried out under a relatively wide temperature condition, and the propylene glycol polyether with controllable molecular weight and narrow distribution is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of polyether polyol preparation, and specifically relates to a method for synthesizing propylene glycol polyether. Background Art

[0002] Propylene glycol polyether is a propylene glycol derivative synthesized by propylene glycol and propylene oxide (abbreviated as: PO) or propylene oxide and ethylene oxide (abbreviated as: EO) under the action of a catalyst. It is a non-ionic surfactant and is widely used in the production of various types of polyurethane elastomers, coatings, adhesives, finishing agents, sealants, water-based polyurethanes and other fields. Propylene glycol polyether has two active hydroxyl groups and can react with polyisocyanates. It is applied to polyurethane and can be used as rigid foam polyurethane insulation materials, as well as soft foam polyurethane materials and polyurethane elastomers. In cosmetics, PPG400 can be used as an emollient, softener, and lubricant. Propylene glycol polyether can also be used as an anti-foaming agent in coatings and hydraulic oils, an anti-foaming agent in synthetic rubber and latex processing, a refrigerant and coolant for heat transfer fluids, and a viscosity improver.

[0003] At present, there are two common synthetic routes for propylene glycol polyether at home and abroad. One is the anion catalytic synthesis process. Anionic polymerization uses inorganic strong base (such as KOH) as a catalyst. Inorganic strong base has the advantages of being cheap and easy to remove in polyether polyols, and is widely used in industrial production when preparing low molecular weight polyether polyols. However, inorganic strong base easily causes propylene oxide to isomerize, producing monohydroxy polyethers with unsaturated double bonds at the end, which reduces the functionality and relative molecular weight of polyether polyols and broadens the distribution, especially when preparing high molecular weight products, the content of monohydroxy polyethers is very high. The second is the bimetallic complex catalytic synthesis process. Although double metal cyanide complex catalysts are highly active in propylene oxide homopolymerization and ethylene oxide / propylene oxide random copolymerization and can produce high molecular weight polyether polyols, they cannot directly use small molecular weight polyols (such as propylene glycol) as initiators. In particular, when double metal cyanide complex catalysts are used for ethylene oxide homopolymerization, ethylene oxide will undergo self-polymerization reaction to generate polyethylene oxide byproducts, thereby affecting the performance of polyether polyols.

[0004] Patent CN106008953A discloses a method for producing polyether polyols, wherein alkylene oxide is homopolymerized under the action of an alkaline catalyst to obtain polyether polyols; the preparation method has high reactivity and can controllably synthesize low molecular weight polyether polyols. However, the process is still not applicable to polyethers with a molecular weight of more than 6000, and the molecular weight distribution is also relatively wide, and the viscosity is relatively high, which cannot meet the high requirements of high-end automobiles, aircraft seat cushions, etc., which require higher molecular weight and lower viscosity.

[0005] Patent CN117887062A provides a scheme for the synergistic catalytic polyetherization using an organic boron non-metallic catalyst and a co-catalyst. However, the organic boron catalyst and co-catalyst used in this patent are only suitable for synthesizing low molecular weight polyether polyols. The molecular weight of the obtained polyether is below 4500, and when the molecular weight reaches above 3500, the distribution of the polyether product synthesized by this process becomes wider and the distribution coefficient becomes larger. Moreover, in this technology, the temperature has a great influence on the reaction, and the molecular weight distribution can only be well controlled within a narrow temperature reaction range. When the temperature exceeds 40°C, although the monomer conversion rate can be improved, the molecular weight distribution will increase significantly.

[0006] Therefore, there is an urgent need to provide a method for synthesizing propylene glycol polyether with controllable molecular weight and narrow distribution, which can be carried out in a relatively mild and Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a method for synthesizing propylene glycol polyether. The synthesis method provided by the present invention can control the molecular weight distribution of propylene glycol polyether, and the reaction conditions are green and mild, and the reaction temperature range is wide, which is conducive to actual production application.

[0008] The invention provides a method for synthesizing propylene glycol polyether.

[0009] Specifically, a method for synthesizing propylene glycol polyether comprises the following steps:

[0010] Propylene glycol, an organic boron catalyst and a co-catalyst are mixed, and then alkylene oxide is introduced at 10 to 80° C. to react, and after the reaction is completed, the reaction system is quenched, and then a solvent is added to the reaction system, and the system is subjected to reduced pressure distillation, washing and drying to obtain propylene glycol polyether;

[0011] The co-catalyst is selected from one or a combination of at least two of trimethylphosphine, triethylphosphine, triphenylphosphine, tri(dimethylamino)phosphine and tripyrrolidinephosphine.

[0012] In some embodiments of the present invention, the organic boron catalyst is selected from one or a combination of at least two of 9-borabicyclo[3.3.1]nonane, dicyclohexylborane, triethylboron, tributylboron, triphenylboron, and tris(pentafluorophenyl)borane.

[0013] In some embodiments of the present invention, the alkylene oxide is ethylene oxide and / or propylene oxide.

[0014] In some embodiments of the present invention, the mass percentage of the ethylene oxide to the alkylene oxide is 0% to 100%.

[0015] In some embodiments of the present invention, the mass ratio of the organic boron catalyst to the co-catalyst is (1-5):1; preferably, the mass ratio of the organic boron catalyst to the co-catalyst is (1.5-3.5):1.

[0016] In some embodiments of the present invention, the amount of the organic boron catalyst is 0.05ppm to 20ppm of the mass of the alkylene oxide; preferably, the amount of the organic boron catalyst is 0.08ppm to 15ppm of the alkylene oxide; further, the amount of the organic boron catalyst is 0.3ppm to 12ppm of the alkylene oxide.

[0017] In some embodiments of the present invention, the molar ratio of the alkylene oxide to the propylene glycol is (5-1500):1.

[0018] In some embodiments of the present invention, the alkylene oxide is introduced at 20-80° C. to carry out the reaction.

[0019] In some embodiments of the present invention, the reaction temperature is 10 to 80°C, and the reaction time is 0.5 to 12 hours. Preferably, the reaction temperature is 20 to 80°C, and the reaction time is 2 to 8 hours. The higher the reaction temperature, the faster the reaction rate and the shorter the required reaction time. Under the catalyst and co-catalyst system selected by the present invention, a wide range of reaction temperatures can be selected. It can react at room temperature (such as 20°C), the reaction conditions are mild and the cost can be reduced; it can also react at a higher temperature (such as 80°C), which increases the reaction rate and monomer conversion rate without affecting the molecular weight distribution.

[0020] In some embodiments of the present invention, the quenching process is: adding a mixture of methanol and hydrochloric acid to the system for quenching. Preferably, the volume ratio of the methanol to the hydrochloric acid is (0.5-2):1; more preferably, the volume ratio of the methanol to the hydrochloric acid is (0.8-1.5):1.

[0021] In some embodiments of the present invention, the solvent is anhydrous ethanol.

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

[0023] (1) The synthesis method provided by the present invention adopts the combination of an organic boron catalyst and a co-catalyst phosphonium salt, and the synergistic effect, through the selection of the co-catalyst, can react under a wide temperature condition to prepare a propylene glycol polyether with a controllable molecular weight and narrow distribution. The synthesis method can not only synthesize polyether polyols with different desired molecular weights; but also make its molecular weight distribution index between 1.0 and 1.05, so as to achieve a controllable molecular weight and narrow distribution of the propylene glycol polyether.

[0024] (2) The synthesis method provided by the present invention has mild reaction conditions and adopts a metal-free catalyst system, which meets the requirements of green chemistry; and the reaction temperature range is relatively wide, which is conducive to practical production applications. DETAILED DESCRIPTION

[0025] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0026] Unless otherwise specified, the raw materials, reagents or devices used in the following examples and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0027] Example 1

[0028] A method for synthesizing propylene glycol polyether comprises the following steps:

[0029] 2.8 mg of triethylboron catalyst TEB, 1.0 mg of triethylphosphine and 76 g of propylene glycol were mixed and added into a 2.5 L reactor, and 230 g of ethylene oxide was slowly introduced at 20°C. After the introduction, the mixture was reacted for 8 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was first added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0030] Example 2

[0031] A method for synthesizing propylene glycol polyether comprises the following steps:

[0032] 2.5 mg of dicyclohexylborane catalyst, 1.5 mg of triphenylphosphine and 76 g of propylene glycol were mixed and added into a 2.5 L reactor, and 660 g of ethylene oxide and 440 g of propylene oxide were slowly introduced at 30°C. After the introduction, the mixture was reacted for 7.5 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0033] Example 3

[0034] A method for synthesizing propylene glycol polyether comprises the following steps:

[0035] 2.6 mg of 9-boranebicyclo[3.3.1]nonane catalyst, 0.8 mg of tri(dimethylamino)phosphine and 76 g of propylene glycol were mixed and added into a 2.5 L reactor, 960 g of ethylene oxide and 1100 g of propylene oxide were slowly introduced at 45°C, and the mixture was reacted for 6 hours after the introduction was completed. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was first added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0036] Example 4

[0037] A method for synthesizing propylene glycol polyether comprises the following steps:

[0038] 2.4 mg of tri(pentafluorophenyl)borane, 1.0 mg of tripyrrolidinephosphine and 76 g of propylene glycol were mixed and added into a 5 L reactor, 1250 g of ethylene oxide and 1650 g of propylene oxide were slowly introduced at 50°C, and the mixture was reacted for 5 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was first added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0039] Example 5

[0040] A method for synthesizing propylene glycol polyether comprises the following steps:

[0041] 2.2 mg of tributyl boron, 1.1 mg of trimethylphosphine and 76 g of propylene glycol were mixed and added into a 5 L reactor, and 2250 g of ethylene oxide and 1750 g of propylene oxide were slowly introduced at 70°C. After the introduction was completed, the mixture was reacted for 4 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0042] Example 6

[0043] A method for synthesizing propylene glycol polyether comprises the following steps:

[0044] 1.2 mg of tributyl boron, 1.2 mg of dicyclohexylborane catalyst, 1.1 mg of trimethylphosphine and 76 g of propylene glycol were mixed and added into an 8 L reactor, 3000 g of ethylene oxide and 2000 g of propylene oxide were slowly introduced at 70°C, and the mixture was reacted for 3 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0045] Example 7

[0046] A method for synthesizing propylene glycol polyether comprises the following steps:

[0047] 2.1 mg of dicyclohexylborane catalyst, 0.6 mg of trimethylphosphine, 0.8 mg of tri(dimethylamino)phosphine and 76 g of propylene glycol were mixed and added into an 8 L reactor, 3650 g of ethylene oxide and 2300 g of propylene oxide were slowly introduced at 80°C, and the mixture was reacted for 2 h. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0048] Example 8

[0049] A method for synthesizing propylene glycol polyether comprises the following steps:

[0050] 1.2 mg of tributyl boron, 1.2 mg of dicyclohexylborane catalyst, 0.6 mg of trimethylphosphine, 0.8 mg of tri(dimethylamino)phosphine and 76 g of propylene glycol were mixed and added into an 8 L reactor, and 7100 g of propylene oxide was slowly introduced at 75°C. After the introduction, the mixture was reacted for 2.5 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0051] Comparative Example 1

[0052] A method for synthesizing propylene glycol polyether comprises the following steps:

[0053] Add 50g of propylene glycol and 3.5g of KOH catalyst into a 2.5L pressure reactor, replace the air in the reactor with nitrogen three times, and after the reactor temperature rises to 110-115°C, dehydrate for 60min under a vacuum degree ≥0.097MPa. After dehydration, slowly add a mixture of 485g of ethylene oxide and 600g of propylene oxide into the reactor, and continue the reaction for 8 hours after the addition is completed.

[0054] Comparative Example 2

[0055] A method for synthesizing propylene glycol polyether comprises the following steps:

[0056] Add 50g of propylene glycol and 2.0g of sodium metal catalyst to a 2.5L pressure reactor, replace the air in the reactor with nitrogen three times and wait for the sodium metal to react with the raw materials. After the sodium metal disappears completely, replace the air in the reactor with nitrogen three times again, then increase the temperature. When the reactor temperature rises to 110-115°C, slowly add a mixture of 485g of ethylene oxide and 600g of propylene oxide, and continue the reaction for 8 hours after the addition is completed.

[0057] Comparative Example 3

[0058] A method for synthesizing propylene glycol polyether comprises the following steps:

[0059] Add 50g of propylene glycol PO400 and 1 drop of phosphoric acid to a 2.5L pressure reactor, replace the air in the reactor with nitrogen three times and then heat it up. After the temperature rises to 110-115°C, dehydrate for 1h, then cool to 80°C and add 0.04g of DMC. Replace nitrogen again and heat up. When the temperature reaches 135°C, slowly add 700g of propylene oxide. After the addition is completed, continue to react for 10min and then cool down for degassing.

[0060] Comparative Example 4

[0061] A method for synthesizing a polyether polyol (the method is the method corresponding to Example 6 in patent CN117887062A), comprising the following steps:

[0062] 2.4 mL of 1,2-butylene oxide, 60 uL of triethylboron catalyst TEB, 20 mg of tetrabutylphosphine bromide and 70 mg of phenylethanol were put into a 10 mL reactor and reacted at 20°C for 8 h. After the reaction, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol to hydrochloric acid is 1:1) was added thereto for quenching, and then dichloromethane was added thereto. After filtering, vacuum distillation, washing and drying, polyether polyols were obtained.

[0063] Comparative Example 5

[0064] A method for synthesizing propylene glycol polyether comprises the following steps:

[0065] 2.1 mg of triethylboron catalyst TEB catalyst, 0.6 mg of trimethylphosphine, 0.8 mg of tetrabutylphosphine bromide and 76 g of propylene glycol were mixed and added into an 8L reactor, and 3650 g of ethylene oxide and 2300 g of propylene oxide were slowly introduced at 80°C. After the introduction, the mixture was reacted for 2 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol and hydrochloric acid was 1:1) was added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0066] Comparative Example 6

[0067] A method for synthesizing propylene glycol polyether comprises the following steps:

[0068] 2.1 mg of triethylboron catalyst TEB catalyst, 0.6 mg of trimethylphosphine, 0.8 mg of tetraphenylphosphine bromide and 76 g of propylene glycol were mixed and added into an 8L reactor, and 3650 g of ethylene oxide and 2300 g of propylene oxide were slowly introduced at 80°C. After the introduction, the mixture was reacted for 2 hours. After the reaction was completed, a mixed solution of methanol and hydrochloric acid (the volume ratio of methanol and hydrochloric acid was 1:1) was first added thereto for quenching, and then anhydrous ethanol was added thereto. The mixture was filtered, distilled under reduced pressure, washed and dried to obtain propylene glycol polyether.

[0069] The polyethers prepared in Examples 1 to 8 and Comparative Examples 1 to 6 were tested, including the actual molecular weight (Mn) and the molecular weight distribution coefficient (D). The test results are shown in Table 1.

[0070] Table 1

[0071]

[0072] As shown in Table 1, the synthesis method provided by the present invention obtains propylene glycol polyether by homopolymerizing alkylene oxide in the presence of propylene glycol through the synergistic effect of an organic boron catalyst and a co-catalyst, and selecting the co-catalyst. The method can synthesize polyether polyols with different required molecular weights and narrow molecular weight distribution by adjusting the ratio of alkylene oxide to propylene glycol. Compared with the base-catalyzed synthesis process, the molecular weight of the synthesized polyether is higher and the distribution index of the product is also narrower (molecular weight distribution index: 1.0-1.05). Although the double metal cyanide complex catalytic process can prepare high molecular weight narrow distribution polyethers, the reaction temperature is 140-145°C, while this process belongs to a non-metallic catalytic reaction and the reaction conditions are mild, which meets the requirements of green chemistry.

[0073] From the data of Comparative Example 4, it can be seen that when the molecular weight of the polyether reaches 4300, the distribution coefficient of the comparative process is 1.24, and the distribution effect is poor, indicating that the organic boron and the co-catalyst used in the process of Comparative Example 4 are only suitable for preparing polyethers with a molecular weight below 4300, which has limitations; and the technology involved in Comparative Example 4 requires strict temperature control, and the temperature above 40°C will seriously affect the molecular weight distribution. The method provided in the embodiment of the present invention can react at 20-80°C to obtain polyether polyols with a narrow molecular weight distribution, which is more conducive to actual production applications.

[0074] It can be seen from the data of Comparative Examples 5 to 6 that when propylene glycol is used as the initiator, the synthesis method provided by the present invention requires the selection of a co-catalyst. When a co-catalyst other than that claimed in the present invention is used, although a polyether polyol with a correspondingly higher molecular weight can be prepared, its molecular weight distribution will increase significantly, and the distribution coefficient will reach about 1.34, and the catalytic effect is obviously not as good as the synthesis method provided in the embodiment of the present invention.

[0075] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for synthesizing propylene glycol polyether, characterized in that: The following steps are involved: Propylene glycol, an organic boron catalyst and a co-catalyst are mixed, and then alkylene oxide is introduced at 10 to 80° C. to react, and after the reaction is completed, the reaction system is quenched, and then a solvent is added to the reaction system, and the system is subjected to reduced pressure distillation, washing and drying to obtain propylene glycol polyether; The co-catalyst is selected from one or a combination of at least two of trimethylphosphine, triethylphosphine, triphenylphosphine, tri(dimethylamino)phosphine and tripyrrolidinephosphine.

2. The synthesis method according to claim 1, characterized in that The organic boron catalyst is selected from one or a combination of at least two of 9-borabicyclo[3.3.1]nonane, dicyclohexylborane, triethylboron, tributylboron, triphenylboron and tri(pentafluorophenyl)borane.

3. The synthesis method according to claim 2, characterized in that The mass ratio of the organic boron catalyst to the co-catalyst is (1-5):

1.

4. The synthesis method according to any one of claims 1 to 3, characterized in that The alkylene oxide is ethylene oxide and / or propylene oxide.

5. The synthesis method according to claim 4, characterized in that The amount of the organic boron catalyst used is 0.05ppm to 20ppm based on the mass of the alkylene oxide.

6. The synthesis method according to any one of claims 1 to 3, characterized in that The molar ratio of the alkylene oxide to the propylene glycol is (5-1500):

1.

7. The synthesis method according to any one of claims 1 to 3, characterized in that Alkylene oxide is introduced at 20-80°C to carry out the reaction.

8. The synthesis method according to claim 7, characterized in that The reaction temperature is 10-80° C., and the reaction time is 0.5-12 h.

9. The synthesis method according to any one of claims 1 to 3, characterized in that The quenching process is: adding a mixed solution of methanol and hydrochloric acid into the system for quenching; the volume ratio of the methanol to the hydrochloric acid is (0.5-2):

1.

10. The synthesis method according to claim 1, characterized in that The solvent is anhydrous ethanol.

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