Preparation method of polyether ester defoaming agent

Abstract

The invention relates to a preparation method of a polyether ester defoaming agent, mainly solves the technical problems of high reaction temperature, high energy consumption, complex preparation process, unfavorable industrial production and the like of the polyether ester defoaming agent in the prior art, and provides the preparation method of the polyether ester defoaming agent. Oleate is obtained by catalyzing oleic acid and small-molecule polyol by using a catalyst 1-methylimidazolium bromide, and can be polymerized with alkylene oxide without a post-treatment process; the multi-block polyether ester structure has good defoaming and foam inhibition performance, and can be applied to the field of defoaming agents.

Description

Technical Field

[0001] The invention relates to a preparation method of a polyether ester defoamer. Background Art

[0002] Polyether defoamers form hydrogen bonds between the polyoxyethylene chains and water molecules, increasing their hydrophilicity and improving their solubility in aqueous solutions. They offer advantages such as strong antifoaming ability, high temperature resistance, resistance to strong acids and alkalis, and excellent stability. They are widely used in fields such as papermaking and water treatment. However, polyether defoamers have relatively poor defoaming capabilities. Polyester defoamers are generally condensates of polyols and polyacids. The presence of ester groups weakens the hydrogen bonds between water molecules and the polyoxyethylene chains, reducing their hydrophilicity and increasing their lipophilicity. This helps reduce surface tension and improves their defoaming ability. However, polyester defoamers have disadvantages such as high cost, susceptibility to hydrolysis, and poor compatibility, which limit their application.

[0003] Polyether ester defoamers came into being based on the combination of polyether defoamers and polyester defoamers. In the prior art for preparing polyether ester defoamers, Chinese patent CN115869663A discloses a method for preparing a multifunctional composite defoamer, which uses glycerol polyoxyethylene polypropylene vinyl ether oleate, PEG400DO and Span-80 as the main raw materials, and utilizes the structural characteristics of polyether esters and the compounding method to improve the anti-foaming ability and stability of the defoamer. However, this invention uses compounding to achieve the purpose of improving the ability of the defoamer, which has the disadvantages of limited scope of use and complicated preparation steps. Chinese patent CN117258358 A first uses an aliphatic initiator to prepare a monofunctional polyether polyol, which needs to be refined and then esterified with fatty acids. The process is relatively complicated, and the application scenario of the resulting polyether ester defoamer is relatively single. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing technology has technical problems such as high reaction temperature, high energy consumption, complex preparation process, and being unfavorable for industrial production in the preparation of polyether ester defoaming agents. A new preparation method of polyether ester defoaming agents is provided, which has the advantages of low reaction temperature, low energy consumption and simple preparation process.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for preparing a polyether ester defoamer comprises the following preparation steps:

[0006] (1) Preparation of oleic acid ester: oleic acid, small molecule polyol, and 1-methylimidazolium bromide are added to container A, and while stirring, a gas inert to the raw material reaction is introduced to replace the air, the reaction pressure is maintained at -0.01 MPa to -0.1 MPa, the temperature is raised to 100 to 120° C., and the reaction is carried out for 5 to 12 hours to obtain oleic acid ester; wherein the molar ratio of the small molecule polyol to oleic acid is 1:1 to 10, and the amount of 1-methylimidazolium bromide added is 0.1% to 1% of the total mass of oleic acid and the small molecule polyol;

[0007] (2) Preparation of crude polyetherester defoamer: Add the above-prepared oleic acid ester and alkali metal catalyst into container B, introduce a gas inert to the raw material reaction to replace the air, maintain the reaction pressure at -0.01Mpa to -0.1Mpa, introduce ethylene oxide in an amount of 5% to 10% of the total mass of oleic acid ester and alkylene oxide, and pressurize for 1h to 2h; introduce propylene oxide in an amount of 20% to 55% of the total mass of oleic acid ester and alkylene oxide, and pressurize for 3h to 6 .... 15% to 35% of the total mass of oleate and alkylene oxide in ethylene oxide, and the internal pressure is 1h to 2h; 5% to 10% of the total mass of oleate and alkylene oxide in propylene oxide, and the internal pressure is 3h to 6h; the reaction temperature is controlled at 110 to 130°C and the reaction pressure is ≤ 0.45Mpa to obtain a crude ether of a polyetherester defoamer, wherein the mass ratio of oleate to the total mass of alkylene oxide is 1:2 to 10, and the amount of alkali metal catalyst added is 0.1% to 1% of the total mass of oleate and alkylene oxide;

[0008] (3) Preparation of polyetherester defoamer refined ether: adding glacial acetic acid to the above-mentioned polyetherester defoamer crude ether for neutralization to obtain polyetherester defoamer refined ether, wherein the molar ratio of glacial acetic acid to alkali metal catalyst is 1 to 3:1.

[0009] In the above scheme, preferably, the molecular weight of the polyetherester defoamer is 800-5000 and the functionality is 2-6.

[0010] In the above scheme, preferably, the small molecule polyol is selected from at least one of propylene glycol, diethylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, pentaerythritol or sorbitol.

[0011] In the above scheme, preferably, the preparation method of 1-methylimidazolium bromide comprises the following steps:

[0012] 1) 1-Methylimidazole and 1-bromobutane were added to a container at a molar ratio of 1:1 to 1.2, and an inert gas to the raw material reaction was introduced to replace the air. The reaction pressure was maintained at -0.01 MPa to -0.1 MPa, and the reaction was carried out at a temperature of 85°C to 115°C for 5 to 12 hours;

[0013] 2) After the reaction is completed, degas at 100° C. to 120° C. for 2 to 5 hours to remove excess 1-bromobutane to obtain the target product, 1-methylimidazolium bromide.

[0014] In the above scheme, preferably, the molar ratio of the small molecule polyol to oleic acid is 1:1-4.

[0015] In the above scheme, preferably, the alkali metal catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, cesium hydroxide, potassium methoxide or sodium methoxide; and the added amount is 0.1% to 0.3% of the total mass of oleate and alkylene oxide.

[0016] In the above scheme, preferably, the molar ratio of the glacial acetic acid to the alkali metal catalyst is 1 to 1.5:1.

[0017] The present invention provides a preparation method of a polyetherester defoamer. Specifically, compared with the p-toluenesulfonic acid catalyst used in the existing process, the reaction temperature required is lower, the obtained polyetherester has a higher esterification rate and better defoaming and anti-foaming performance, and the reaction process is simple and does not require post-processing. DETAILED DESCRIPTION

[0018] [Example 1]

[0019] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 662g of oleic acid, 180g of glycerol, and 0.85g of 1-methylimidazolium bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate I.

[0020] To a 5L autoclave, add 500g of oleate ester I and 6.8g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 141g of ethylene oxide is introduced at a constant rate for 1 hour; 1466g of propylene oxide is introduced for 3 hours; 422g of ethylene oxide is introduced for 1 hour; and 281g of propylene oxide is introduced for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain crude polyetherester defoamer I. 7.9g of glacial acetic acid is added dropwise to the crude polyetherester defoamer I for neutralization to obtain refined polyetherester defoamer I.

[0021] [Example 2]

[0022] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 300g of oleic acid, 78g of propylene glycol, and 0.76g of 1-methylimidazolium bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, and the temperature was raised to 115°C. The reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate II.

[0023] To a 5L autoclave, add 350g of oleate II and 7.7g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 206g of ethylene oxide is introduced at a uniform rate for 1 hour; 1297g of propylene oxide is introduced for 3 hours; 566g of ethylene oxide is introduced for 1 hour; and 155g of propylene oxide is introduced for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer II ether. 9.1g of glacial acetic acid is added dropwise to the crude polyetherester defoamer II ether for neutralization to obtain a refined polyetherester defoamer II ether.

[0024] [Example 3]

[0025] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 600g of oleic acid, 145g of pentaerythritol, and 2.2g of 1-methylimidazole bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate III.

[0026] To a 5L kettle, add 664g of oleate III and 6.1g of potassium hydroxide. Nitrogen is introduced to displace the air in the kettle, while maintaining a vacuum. At a pressure of -0.01 MPa, 300g of ethylene oxide is introduced at a uniform rate for 1 hour, followed by 986g of propylene oxide for 3 hours, 900g of ethylene oxide for 1 hour, and 150g of propylene oxide for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain crude polyetherester defoamer III ether. 9.8g of glacial acetic acid is added dropwise to the crude polyetherester defoamer III ether for neutralization to obtain refined polyetherester defoamer III ether.

[0027] [Example 4]

[0028] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 1000g of oleic acid, 162g of sorbitol, and 1.2g of 1-methylimidazole bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate IV.

[0029] To a 5L autoclave, add 600g of oleate IV and 5.2g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave, maintaining a vacuum. At a pressure of -0.01 MPa, 242g of ethylene oxide is introduced at a uniform rate for 1 hour; 539g of propylene oxide is introduced for 3 hours; 848g of ethylene oxide is introduced for 1 hour; and 194g of propylene oxide is introduced for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer IV ether. 7.2g of glacial acetic acid is added dropwise to the crude polyetherester defoamer IV ether for neutralization to obtain a refined polyetherester defoamer IV ether.

[0030] [Example 5]

[0031] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 700g of oleic acid, 330g of trimethylolpropane, and 2.82g of 1-methylimidazole bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate V.

[0032] To a 5L kettle, add 300g of oleate V and 3.2g of potassium hydroxide. Nitrogen is introduced to displace the air in the kettle, while maintaining a vacuum. At a pressure of -0.01 MPa, 226g of ethylene oxide, 1208g of propylene oxide, 980g of ethylene oxide, and 302g of propylene oxide are introduced at a constant rate, respectively, for 1 hour. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude ether of polyetherester defoamer V. 3.5g of glacial acetic acid is added dropwise to the crude ether of polyetherester defoamer V for neutralization to obtain a refined ether of polyetherester defoamer V.

[0033] [Example 6]

[0034] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 800g of oleic acid, 170g of 1,4-butanediol, and 1.79g of 1-methylimidazole bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate VI.

[0035] To a 5L autoclave, add 950g of oleate VI and 4.5g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 150g of ethylene oxide is introduced at a constant rate for 1 hour; 995g of propylene oxide is introduced at a constant rate for 3 hours; 598g of ethylene oxide is introduced at a constant rate for 1 hour; and 299g of propylene oxide is introduced at a constant rate for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer VI ether. 5.9g of glacial acetic acid is added dropwise to the crude polyetherester defoamer VI ether for neutralization to obtain a refined polyetherester defoamer VI ether.

[0036] [Comparative Example 1]

[0037] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 662g of oleic acid, 180g of glycerol, and 0.85g of p-toluenesulfonic acid were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate VII.

[0038] To a 5L autoclave, add 500g of oleate VII and 6.8g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 141g of ethylene oxide, 1466g of propylene oxide, 422g of ethylene oxide, and 281g of propylene oxide are introduced at a constant rate, respectively, for 1 hour. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer VII ether. 7.9g of glacial acetic acid is added dropwise to the crude polyetherester defoamer VII ether for neutralization to obtain a refined polyetherester defoamer VII ether.

[0039] [Comparative Example 2]

[0040] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 662g of oleic acid, 180g of glycerol, and 0.85g of p-toluenesulfonic acid were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 180°C, the reaction time was 10h, and vacuum degassing was carried out for 2h to obtain oleate VIII.

[0041] To a 5L autoclave, add 500g of oleate VII and 6.8g of potassium hydroxide. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 141g of ethylene oxide is introduced at a constant rate for 1 hour; 1466g of propylene oxide is introduced at a constant rate for 3 hours; 422g of ethylene oxide is introduced at a constant rate for 1 hour; and 281g of propylene oxide is introduced at a constant rate for 3 hours. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer VII ether. 7.9g of glacial acetic acid is added dropwise to the crude polyetherester defoamer VII ether for neutralization to obtain a refined polyetherester defoamer VIII ether.

[0042] [Comparative Example 3]

[0043] A 2L high-temperature and high-pressure reactor equipped with a stirrer was charged with 60g of glycerol and 2.8g of potassium hydroxide. The stirred reactor was started, and nitrogen was introduced to displace the air in the reactor. The reactor was maintained in a vacuum state and the temperature was raised to 115°C. At a pressure of -0.01 MPa, 65g of ethylene oxide was introduced at a constant rate for 1 hour; 682g of propylene oxide was introduced for 3 hours; 196g of ethylene oxide was introduced for 1 hour; and 130g of propylene oxide was introduced for 3 hours. The reaction temperature was maintained at 110-130°C and the reaction pressure was ≤0.45 MPa to obtain a crude polyether polyol a.

[0044] Add 65 g of deionized water to the crude polyether polyol a, control the reactor temperature at 80-85°C, add 10.3 g of a 50% phosphoric acid aqueous solution dropwise, and stir for 1 hour; add 4.5 g of magnesium silicate and 6.8 g of aluminum silicate to the reactor, stir for 1 hour, control the reactor temperature at 100-120°C, and vacuum dehydrate until the moisture content is less than 0.1% to obtain the refined polyether polyol a.

[0045] Add 868g of polyether polyol a refined ether, 141g of oleic acid, and 1.10g of 1-methylimidazole bromide into a 2L kettle, start the stirred kettle, introduce nitrogen to replace the air in the kettle, maintain the vacuum state in the kettle, heat to 115°C, react for 10h, and vacuum degas for 2h to obtain polyether ester defoamer IX.

[0046] [Comparative Example 4]

[0047] Into a 2L high-temperature and high-pressure reactor equipped with a stirring device, 662 g of oleic acid, 180 g of glycerol, and 0.85 g of 1-methylimidazolium bromide were added. The stirring reactor was turned on and nitrogen was introduced to replace the air in the reactor. The reactor was kept in a vacuum state, the temperature was raised to 115°C, the reaction time was 10 h, and vacuum degassing was carried out for 2 h to obtain oleate IX.

[0048] To a 5L autoclave, add 9500g of oleate and 6.8g of potassium hydroxide as a catalyst. Nitrogen is introduced to displace the air in the autoclave while maintaining a vacuum. At a pressure of -0.01 MPa, 400g of ethylene oxide and 1244g of propylene oxide are introduced at a uniform rate for 1 hour and 3 hours, respectively. The reaction temperature is controlled at 110-130°C and the reaction pressure is ≤0.45 MPa to obtain a crude polyetherester defoamer IX ether. 7.9g of glacial acetic acid is added dropwise to the crude polyetherester defoamer IX ether for neutralization to obtain a refined polyetherester defoamer IX ether.

[0049] Table 1 Physical property test indicators of polyether ester polyols prepared in Examples 1-6 and Comparative Examples 1-3

[0050]

[0051]

[0052] As shown in Table 1, Examples 1-6 and Comparative Example 1 demonstrate that oleate polyether polyols prepared using 1-methylimidazolium bromide at relatively low temperatures exhibit high esterification yields, whereas achieving the same esterification yield using p-toluenesulfonic acid requires higher reaction temperatures. The process for preparing oleate polyether polyols in Comparative Example 3 not only requires post-treatment of the pre-synthesized polyether polyol, but also results in a relatively low esterification yield.

[0053] Performance evaluation method of defoaming agent:

[0054] Foam breaking performance: Pour 100ml of foaming liquid into a 600ml graduated cylinder, cap tightly with a stopper, and clamp the cylinder to an oscillator for 100 times (ensure that the cylinder is full of foam). Remove the cylinder immediately after oscillation. Use a dropper to accurately and evenly add a certain amount of polyetherester polyol to the upper port of the cylinder. Immediately start a stopwatch after addition and record the foam height at different times. Repeat three times for each sample in parallel. Calculate the average foam height as the standard for evaluating the defoamer performance. The higher the foam, the worse the defoamer's foam breaking performance, and vice versa.

[0055] Foam suppression performance: record the foam height at that time, repeat each sample 3 times in parallel, and calculate the average foam height as the standard for evaluating the foam suppression performance of the defoamer. The higher the foam height, the worse the foam suppression performance of the defoamer, and vice versa.

[0056] Table 2 Defoaming performance test of polyether ester polyols prepared in Examples 1-6 and Comparative Examples 1-3

[0057]

[0058] It can be seen from the defoaming performance test data of polyether ester polyols in Table 2 that the polyether ester polyols prepared in Examples 1-6 have relatively excellent anti-foaming and defoaming properties. The defoaming performance test data of Examples 1-6 and Comparative Example 1 and Comparative Example 2 show that the anti-foaming and defoaming properties of oleate polyether polyols obtained by catalysis of 1-methylimidazole bromide at a relatively low temperature are better than those of oleate polyether polyols obtained by catalysis of p-toluenesulfonic acid. The defoaming performance test data of Examples 1-6 and Comparative Example 3 show that the anti-foaming and defoaming properties of polyether ester polyols obtained by directly catalyzing the esterification of polyether polyols with oleic acid by 1-methylimidazole bromide are poor. The defoaming performance test data of Examples 1-6 and Comparative Example 3 show that multi-block polyether ester polyols have better defoaming and defoaming properties.

Claims

1. A method for preparing a polyetherester defoamer, comprising the following steps: (1) Preparation of oleic acid ester: oleic acid, small molecule polyol, and 1-methylimidazolium bromide are added to container A, and while stirring, a gas inert to the raw material reaction is introduced to replace the air, the reaction pressure is maintained at -0.01 MPa to -0.1 MPa, the temperature is raised to 100 to 120°C, and the reaction is carried out for 5 to 12 hours to obtain oleic acid ester; wherein, The molar ratio of the small molecule polyol to oleic acid is 1:1-10, and the amount of 1-methylimidazolium bromide added is 0.1%-1% of the total mass of oleic acid and the small molecule polyol; (2) Preparation of crude polyetherester defoamer: Add the above-prepared oleic acid ester and alkali metal catalyst into container B, introduce a gas inert to the raw material reaction to replace the air, maintain the reaction pressure at -0.01Mpa to -0.1Mpa, introduce ethylene oxide in an amount of 5% to 10% of the total mass of oleic acid ester and alkylene oxide, and pressurize for 1h to 2h; introduce propylene oxide in an amount of 20% to 55% of the total mass of oleic acid ester and alkylene oxide, and pressurize for 3h to 6 .... 15% to 35% of the total mass of oleate and alkylene oxide in ethylene oxide, and the internal pressure is 1h to 2h; 5% to 10% of the total mass of oleate and alkylene oxide in propylene oxide, and the internal pressure is 3h to 6h; the reaction temperature is controlled at 110 to 130°C and the reaction pressure is ≤ 0.45Mpa to obtain a crude ether of a polyetherester defoamer, wherein the mass ratio of oleate to the total mass of alkylene oxide is 1:2 to 10, and the amount of alkali metal catalyst added is 0.1% to 1% of the total mass of oleate and alkylene oxide; (3) Preparation of polyetherester defoamer refined ether: adding glacial acetic acid to the above-mentioned polyetherester defoamer crude ether for neutralization to obtain polyetherester defoamer refined ether, wherein the molar ratio of glacial acetic acid to alkali metal catalyst is 1 to 3:

1.

2. The method for preparing a polyetherester defoamer according to claim 1, wherein The molecular weight of the polyetherester defoamer is 800-5000 and the functionality is 2-6.

3. The preparation method of the polyetherester defoamer according to claim 1, wherein The small molecule polyol is selected from at least one of propylene glycol, diethylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, pentaerythritol or sorbitol.

4. The method for preparing a polyetherester defoamer according to claim 1, wherein The preparation method of 1-methylimidazolium bromide comprises the following steps: 1) 1-Methylimidazole and 1-bromobutane were added to a container at a molar ratio of 1:1 to 1.2, and an inert gas to the raw material reaction was introduced to replace the air. The reaction pressure was maintained at -0.01 MPa to -0.1 MPa, and the reaction was carried out at a temperature of 85°C to 115°C for 5 to 12 hours; 2) After the reaction is completed, degas at 100° C. to 120° C. for 2 to 5 hours to remove excess 1-bromobutane to obtain the target product, 1-methylimidazolium bromide.

5. The method for preparing a polyetherester defoamer according to claim 1, wherein The molar ratio of the small molecule polyol to oleic acid is 1:1-4.

6. The method for preparing a polyetherester defoamer according to claim 1, wherein The alkali metal catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, cesium hydroxide, potassium methoxide or sodium methoxide; and the added amount is 0.1% to 0.3% of the total mass of oleic acid ester and alkylene oxide.

7. The method for preparing a polyetherester defoamer according to claim 1, wherein The molar ratio of the glacial acetic acid to the alkali metal catalyst is 1-1.5:1.

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