Preparation method of low-foam surfactant polyether polyol

Abstract

The invention provides a preparation method of low-foam surfactant polyether polyol, and relates to the technical field of surfactants, the preparation method comprises the following steps: placing 138 parts by weight of C8-C13 straight-chain fatty alcohol, 76-210 parts by weight of polyol and 0.2 part by weight of a first catalyst in a high-pressure reaction kettle, firstly carrying out hydroxyl conversion, then carrying out an etherification reaction to obtain alcohol ether, and then adding a second catalyst into the high-pressure reaction kettle to obtain a polyether polyol product; removing small molecular substances generated in the reaction after etherification is finished; adding 1-1.5 parts of a second catalyst, continuously adding 264-290 parts of epoxide while stirring, carrying out ring-opening polymerization reaction at the temperature of 110-160 DEG C under the pressure of 0.1-0.3 MPa, and curing for 3-5 hours to generate crude polyether polyol; and then adding 1.5 parts of a post-treatment agent, and carrying out neutralization treatment to obtain a final product. The polyether polyol prepared by the method has the advantages of high conversion rate, low foam, good cleaning effect, low environmental load and the like.

Description

Technical Field

[0001] The invention relates to the technical field of surfactants, in particular to a method for preparing a low-foaming surfactant polyether polyol. Background Art

[0002] In the field of surfactants, surface-active polyether polyols, as core components of industrial cleaning agents, play a key role in cleaning effectiveness. The structure of the initiator alcohol and the efficiency of the epoxide ring-opening grafting are important factors in determining the performance of polyether polyols. Currently, commonly used initiator alcohols include secondary alcohols (containing 8-13 carbon atoms), C8-C13 primary alcohols, and isomeric alcohols.

[0003] When using secondary alcohols as initiators, existing processes have significant drawbacks. Specifically, the conversion rate of the epoxide-alcohol reaction is only approximately 50%, leaving a large amount of unreacted epoxide as monomer in the product system. This not only requires complex post-processing steps such as distillation and adsorption to remove the residual monomer, significantly increasing production costs, but the residue can also cause problems such as abnormal viscosity and poor foam stability in the polyether polyol, severely limiting its application in high-end industrial cleaning applications.

[0004] While using C8-C13 primary or isomeric alcohols as initiators can avoid some of the issues associated with secondary alcohols, polyethers are often prepared through epoxide ring-opening polymerization using a batch process. However, this process has the following drawbacks: First, the reaction efficiency is low. Limited by mass transfer efficiency and catalyst activity, epoxide conversion is incomplete, and the concentration of residual unreacted monomer in the system after the reaction often exceeds 5000 ppm. Second, there are high environmental risks. If the residual epoxide is not recovered through an exhaust gas treatment system or treated harmlessly through catalytic combustion, it is directly discharged, resulting in a sharp increase in COD values in the water. Third, product performance is limited. Residual monomers cause an imbalance in the HLB value of the polyether, resulting in reduced detergency of the cleaning agent and excessive foaming, which can easily cause secondary contamination of workpieces during the oil cleaning process on metal surfaces.

[0005] In summary, it is urgent to develop a new process with high conversion rate, low foam, good cleaning effect and low environmental load, which is of great significance to promoting the development of the surfactant industry. Summary of the Invention

[0006] In order to address the deficiencies in the prior art, the present invention provides a method for preparing a low-foaming surfactant polyether polyol. The polyether polyol prepared by this method has the advantages of high conversion rate, low foam, good cleaning effect, and low environmental load.

[0007] In order to achieve the above object, the specific scheme adopted by the present invention is: A method for preparing a low-foaming surfactant polyether polyol mainly comprises the following steps: Step 1: Weigh 138 parts of C8-C13 straight-chain fatty alcohol, 76-210 parts of polyol, 0.2 parts of the first catalyst, 1-1.5 parts of the second catalyst, 264-290 parts of epoxide and 1.5 parts of the post-treatment agent in parts by weight, and set aside; Step 2: placing a C8-C13 straight-chain fatty alcohol, a polyol, and a first catalyst in a high-pressure reactor with an external circulation device, stirring them uniformly, first performing hydroxyl conversion, and then performing an etherification reaction at a temperature of 140-240° C. and a vacuum degree controlled at -0.025 MPa for 4-6 hours to obtain an alcohol ether. After the etherification is completed, the small molecular substances produced in the reaction are removed; Step 3: Add the second catalyst to the autoclave, then continuously add the epoxide while stirring at a speed of 30-85 rpm, and undergo a ring-opening polymerization reaction at a temperature of 110-160° C. and a pressure of 0.1-0.3 MPa. The mixture is aged for 3-5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches more than 20% of the total amount, the external circulation device is turned on to optimize mass and heat transfer to ensure continuous reaction. After step 4 and step 3 are completed, the pressure of the autoclave is discharged to 0 MPa, and a post-treatment agent is added to the autoclave for neutralization treatment to obtain the final product.

[0008] Furthermore, the C8-C13 straight-chain fatty alcohol is selected from C8 alcohol or C13 alcohol.

[0009] Furthermore, the polyol is selected from diol and / or triol.

[0010] Furthermore, the polyol is selected from any one or more of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol.

[0011] Furthermore, the first catalyst is zinc acetate or antimony trioxide.

[0012] Furthermore, the second catalyst is selected from one or more of potassium hydroxide, sodium hydroxide, dodecyl tertiary amine, and tridecyl tertiary amine.

[0013] Furthermore, the epoxide is one or more of ethylene oxide, propylene oxide, epichlorohydrin, and butylene oxide.

[0014] Furthermore, the post-treatment agent is at least one of glacial acetic acid, phosphoric acid, and citric acid.

[0015] Beneficial effects: (1) The present invention first etherifies fatty alcohols to obtain alcohol ethers, and then reacts them with epoxides, abandoning the process of directly connecting epoxides to primary or secondary alcohols in the prior art, significantly improving the reaction conversion rate from the traditional 50.0% to more than 99.5%. This greatly reduces the residual unreacted epoxide monomers, not only reducing the cost of removing residual monomers through complex post-processing steps such as distillation and adsorption, but also avoiding the quality problems of polyether polyols caused by residual monomers, indirectly improving the product profit margin; at the same time, the method of obtaining alcohol ethers by etherifying fatty alcohols reduces the difficulty of alcohol ether production, and the cost of raw materials is also reduced, giving the product a significant cost advantage. The preparation method effectively overcomes the defects of the prior art of using C8-C13 primary alcohols as initiators, such as poor cleaning power of polyethers, incomplete removal of oil stains on the workpiece surface, and excessive foaming. The polyether polyols prepared by the present invention perform well in the cleaning process, have a significant effect on removing oil stains on metal workpieces, can effectively avoid secondary contamination of workpieces, and exhibit excellent cleaning effects, meeting the needs of industrial cleaning, especially high-end cleaning.

[0016] (2) On the one hand, the polyether polyol prepared by the present invention has a suitable molecular structure. By controlling the type and amount of raw materials, the HLB value (hydrophile-lipophile balance) of the polyether polyol can be precisely controlled. The appropriate HLB value enables the polyether polyol to better balance the hydrophilicity and lipophilicity during the cleaning process, effectively reducing the surface tension and quickly emulsifying and dispersing the oil without generating excessive foam. On the other hand, during the reaction process, the high conversion rate reduces the residual epoxide monomer, avoiding the problem of HLB value imbalance of the polyether polyol caused by the monomer, thereby ensuring the good detergency of the cleaning agent and reducing the generation of foam. In particular, in the cleaning of oil stains on metal surfaces, it can effectively avoid secondary contamination of the workpiece and achieve excellent cleaning effect.

[0017] (3) From the perspective of raw materials, the raw materials used in the present invention can fully participate in the reaction during the reaction process, reducing the residual unreacted monomers. For example, in the use of epoxides, the high conversion rate significantly reduces the residual amount, reducing environmental pollution. In the production process, the use of external circulation devices and appropriate reaction conditions improves reaction efficiency and reduces energy consumption. At the same time, the neutralization treatment of the post-treatment agent further reduces the content of harmful substances in the product, significantly reducing the environmental load of the final product and reducing pollution to water bodies and other environments, which is in line with the concept of sustainable development.

[0018] (4) The present invention can precisely control the structure and properties of polyether polyols by selecting fatty alcohols (initiators), polyols, and epoxides and adjusting the ratios between them. For example, the selection of C8-C13 straight-chain fatty alcohols with different carbon chain lengths can change the lipophilicity of the polyether polyols; the selection of different types of polyols, such as diols or triols, can adjust the molecular chain structure and the number of functional groups of the polyether polyols, thereby affecting the viscosity, hydroxyl value and other performance indicators of the polyether polyols. In addition, by controlling the reaction conditions, such as reaction temperature, pressure, time and the amount of catalyst, the properties of the polyether polyols can also be finely controlled to meet the diverse performance requirements of the polyether polyols in different industrial fields. DETAILED DESCRIPTION

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0020] The present invention provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C8-C13 straight-chain fatty alcohol, 76-210 parts of polyol, 0.2 parts of the first catalyst, 1-1.5 parts of the second catalyst, 264-290 parts of epoxide and 1.5 parts of the post-treatment agent in parts by weight, and set aside; Step 2: Place a C8-C13 straight-chain fatty alcohol, a polyol, and a first catalyst in a high-pressure reactor equipped with an external circulation device, stir them evenly, first perform hydroxyl conversion, and then perform an etherification reaction at a temperature of 140-240°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure state) for 4-6 hours to obtain an alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add the second catalyst to the autoclave of step 2, then continuously add the epoxide while stirring at a speed of 30-85 rpm, and undergo a ring-opening polymerization reaction at a temperature of 110-160° C. and a pressure of 0.1-0.3 MPa. The reaction is aged for 3-5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches more than 20% of the total amount, the external circulation device is turned on to optimize mass and heat transfer to ensure continuous reaction. After step 4 and step 3, the pressure of the autoclave is discharged to 0 MPa, and a post-treatment agent is added to the autoclave to neutralize the catalyst by the post-treatment agent to prevent degradation during storage, thereby obtaining the final product.

[0021] The preparation method realizes the synthesis of low-foaming polyether polyols through three-step reactions: (1) hydroxyl conversion and etherification: C8-C13 fatty alcohols and polyols are dehydrated and condensed with zinc acetate or antimony trioxide as catalysts to generate branched alcohol ethers (containing hydrophobic chains and multiple active hydroxyl groups); (2) ring-opening polymerization: with the help of a second catalyst, alcohol ethers and epoxides are subjected to anionic ring-opening polymerization to form polyether chains. The external circulation device optimizes mass transfer and heat transfer in the middle and late stages of the reaction and regulates the molecular weight distribution; (3) neutralization and purification: remove residual catalysts and impurities.

[0022] Among them, C8-C13 straight-chain fatty alcohols serve as hydrophobic initiators. Their carbon chain length influences the hydrophilic-hydrophobic balance of the product, thereby regulating surface activity and foam performance. C8-C13 straight-chain fatty alcohols are conventional alcohols in the art, preferably C8 or C13 alcohols.

[0023] Polyols are used to provide a polyhydroxy structure, increase molecular branching, reduce product crystallinity, and enhance solubility. The polyols are various polyols commonly used in the art, preferably including diols and / or triols, more preferably any one or more of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol.

[0024] The first catalyst promotes the dehydration condensation (etherification reaction) of hydroxyl groups to form an initial ether bond structure. The first catalyst is selected from zinc acetate or antimony trioxide.

[0025] The second catalyst acts as an initiator for subsequent ring-opening polymerization to activate the epoxide. The second catalyst is an alkali metal hydroxide, more preferably one or more of potassium hydroxide, sodium hydroxide, dodecyl tertiary amine, and tridecyl tertiary amine.

[0026] The epoxides are various epoxides commonly used in the art, preferably one or more of ethylene oxide, propylene oxide, epichlorohydrin, and butylene oxide.

[0027] The external circulation device is any of the conventional external circulation devices and condensation reflux devices used in the art, and preferably includes a shielded pump and a heat exchanger.

[0028] The autoclave preferably further includes a top nozzle. When the cumulative amount of epoxide added reaches more than 20% of the total amount, the external circulation device is turned on, so that the subsequent addition of epoxide is added through the external circulation pipeline. The epoxide in the external circulation pipeline is heat exchanged through the heat exchanger (so that the reaction temperature is stably controlled at 120-140°C) and then sprayed into the autoclave through the top nozzle, so that the materials are evenly mixed and the reaction is sufficient.

[0029] The post-treatment agent is an acidic substance, preferably at least one of glacial acetic acid, phosphoric acid, and citric acid.

[0030] The low-foaming properties of this low-foaming polyether polyol are derived from the synergistic effect of the following three components: (1) The long carbon chain structure of the C8-C13 linear fatty alcohol reduces the adsorption capacity of surfactants at the liquid-air interface by enhancing the molecular hydrophobicity, thereby reducing the initial generation of foam; (2) The polyol introduces a branched network formed by polyhydroxy compounds, which increases the steric hindrance of the molecular chain, weakens the mechanical strength of the foam liquid film, and accelerates foam collapse; (3) By optimizing the type and ratio of epoxides, the molecular structure of the polyether is precisely adjusted to inhibit the stability and merging of bubbles. The synergistic effect of these three components not only reduces the dynamic surface tension of the system (reducing foam generation), but also destroys the durability of foam through molecular structure design, ultimately achieving high-efficiency low-foaming performance. This feature is particularly suitable for industrial cleaning scenarios, avoiding the problems of secondary contamination of workpieces or reduced equipment efficiency caused by excessive foaming of traditional surfactants.

[0031] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0032] The technical solution of the present invention is described in detail below with reference to specific examples. It should be noted that the reagents and raw materials used in the present invention are all commercially available.

[0033] Example 1 This embodiment provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C8 alcohol, 106 parts of diethylene glycol, 0.2 parts of zinc acetate, 1 part of potassium hydroxide, 264 parts of ethylene oxide and 1.5 parts of glacial acetic acid, and set aside; Step 2: Place C8 alcohol, diethylene glycol, and zinc acetate in a high-pressure reactor equipped with an external circulation device, stir evenly, first perform hydroxyl conversion, and then perform etherification reaction at a temperature of 240°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure) for 4 hours to obtain alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add potassium hydroxide to the autoclave of step 2, then continuously add epoxide while stirring at 50 rpm, and undergo ring-opening polymerization at a temperature of 160° C. and a pressure of 0.3 MPa. The mixture is aged for 3 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 53 parts) of the total amount, the external circulation device (connected to the external circulation heat exchanger via a shielded pump) is turned on to ensure the continuous progress of the ring-opening polymerization reaction. After step 4 and step 3, the pressure of the autoclave is discharged to 0 MPa, and glacial acetic acid is added to the autoclave for neutralization to obtain the final product.

[0034] Example 2 This embodiment provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C8 alcohol, 76 parts of ethylene glycol, 0.2 parts of antimony trioxide, 1 part of potassium hydroxide, 264 parts of ethylene oxide and 1.5 parts of phosphoric acid in parts by weight and set aside; Step 2: Place C8 alcohol, ethylene glycol and antimony trioxide in a high-pressure reactor equipped with an external circulation device, stir evenly, first perform hydroxyl conversion, and then perform etherification reaction at a temperature of 140°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure) for 6 hours to obtain alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add potassium hydroxide to the autoclave of step 2, and then continuously add epoxide while stirring at a speed of 50 rpm. Ring-opening polymerization reaction occurs at a temperature of 110° C. and a pressure of 0.1 MPa. The mixture is aged for 5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 53 parts) of the total amount, the external circulation device is turned on (connected to the external circulation heat exchanger via a shielded pump) to ensure the continuous progress of the ring-opening polymerization reaction. After step 4 and step 3 are completed, the pressure of the autoclave is discharged to 0 MPa, and phosphoric acid is added to the autoclave for neutralization to obtain the final product.

[0035] Example 3 This embodiment provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C13 alcohol, 166 parts of triethylene glycol, 0.2 parts of zinc acetate, 1 part of sodium hydroxide, 100 parts of propylene oxide, 164 parts of ethylene oxide, 25 parts of butylene oxide and 1.5 parts of citric acid in parts by weight and set aside; Step 2: Place C13 alcohol, triethylene glycol, and zinc acetate in a high-pressure reactor equipped with an external circulation device, stir evenly, first perform hydroxyl conversion, and then perform etherification reaction at a temperature of 240°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure) for 4 hours to obtain alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add sodium hydroxide to the autoclave of step 2, and then continuously add epoxide while stirring at a speed of 50 rpm. Ring-opening polymerization reaction occurs at a temperature of 160° C. and a pressure of 0.3 MPa. The mixture is aged for 5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 58 parts) of the total amount, the external circulation device is turned on (connected to the external circulation heat exchanger via a shielded pump) to ensure the continuous progress of the ring-opening polymerization reaction. After step 4 and step 3 are completed, the pressure of the autoclave is discharged to 0 MPa, and citric acid is added to the autoclave for neutralization to obtain the final product.

[0036] Example 4 This embodiment provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C13 alcohol, 76 parts of propylene glycol, 134 parts of dipropylene glycol, 0.2 parts of zinc acetate, 1 part of sodium hydroxide, 100 parts of epichlorohydrin, 164 parts of ethylene oxide, and 1.5 parts of glacial acetic acid, and set aside; Step 2: Place C13 alcohol, propylene glycol, dipropylene glycol, and zinc acetate in a high-pressure reactor equipped with an external circulation device, stir evenly, first perform hydroxyl conversion, and then perform etherification reaction at a temperature of 240°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure) for 4 hours to obtain alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add sodium hydroxide to the autoclave of step 2, and then continuously add epoxide while stirring at a speed of 50 rpm. Ring-opening polymerization reaction occurs at a temperature of 160° C. and a pressure of 0.3 MPa. The mixture is aged for 5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 53 parts) of the total amount, the external circulation device (connected to the external circulation heat exchanger via a shielded pump) is turned on to ensure the continuous progress of the ring-opening polymerization reaction. After step 4 and step 3, the pressure of the autoclave is discharged to 0 MPa, and glacial acetic acid is added to the autoclave for neutralization to obtain the final product.

[0037] Example 5 This embodiment provides a method for preparing a low-foaming surfactant polyether polyol, which mainly comprises the following steps: Step 1: Weigh 138 parts of C13 alcohol, 192 parts of tripropylene glycol, 0.2 parts of zinc acetate, 1 part of dodecyl tertiary amine, 0.5 parts of tridecyl tertiary amine, 100 parts of propylene oxide, 164 parts of ethylene oxide, 20 parts of butylene oxide and 1.5 parts of glacial acetic acid, and set aside; Step 2: Place C13 alcohol, tripropylene glycol, and zinc acetate in a high-pressure reactor equipped with an external circulation device, stir evenly, first perform hydroxyl conversion, and then perform etherification reaction at a temperature of 240°C and a vacuum degree controlled at -0.025 MPa (slightly negative pressure) for 4 hours to obtain alcohol ether. After the etherification is completed, remove the small molecular substances produced in the reaction; Step 3: Add dodecyl tertiary amine and tridecyl tertiary amine to the autoclave of step 2, and then continuously add epoxides (propylene oxide, ethylene oxide, and butylene oxide) while stirring at a speed of 50 rpm. Ring-opening polymerization reaction occurs at a temperature of 160° C. and a pressure of 0.3 MPa. The mixture is aged for 5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 57 parts) of the total amount, the external circulation device is turned on (connected to the external circulation heat exchanger via a shielded pump) to ensure the continuous progress of the ring-opening polymerization reaction. After step 4 and step 3, the pressure of the autoclave is discharged to 0 MPa, and glacial acetic acid is added to the autoclave for neutralization to obtain the final product.

[0038] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that in step 1, isomeric decanol is used instead of C8 alcohol.

[0039] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the raw materials do not contain antimony trioxide.

[0040] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that the raw materials do not contain potassium hydroxide.

[0041] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that the number of parts of sodium hydroxide in the raw materials is 2 parts.

[0042] Comparative Example 5 The difference between Comparative Example 5 and Example 4 is that the raw materials do not contain propylene glycol and dipropylene glycol.

[0043] Comparative Example 6 This comparative example provides a method for preparing a surfactant, which mainly comprises the following steps: Step 1: Weigh 138 parts of C13 alcohol, 192 parts of tripropylene glycol, 1 part of dodecyl tertiary amine, 0.5 parts of tridecyl tertiary amine, 100 parts of propylene oxide, 164 parts of ethylene oxide, 20 parts of butylene oxide and 1.5 parts of glacial acetic acid, and set aside; Step 2: Add C13 alcohol and tripropylene glycol to a high-pressure reactor, followed by adding dodecyl tertiary amine and tridecyl tertiary amine. Then, continuously add epoxides (propylene oxide, ethylene oxide, and butylene oxide) while stirring at 50 rpm. The reaction is carried out at a temperature of 160°C and a pressure of 0.3 MPa, and the mixture is aged for 5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches 20% (i.e., 57 parts) of the total amount, the external circulation device is turned on (connected to the external circulation heat exchanger via a shielded pump) to ensure the continuous progress of the reaction. After step 3 and step 2 are completed, the pressure of the autoclave is discharged to 0 MPa, and glacial acetic acid is added to the autoclave for neutralization to obtain the final product.

[0044] The hydroxyl value, viscosity, and reaction conversion rate of the products obtained in Examples 1-5 and Comparative Examples 1-6 were tested, and the appearance of the products was observed. The results are shown in Table 1.

[0045] Table 1 Hydroxyl value, viscosity, reaction conversion rate, and appearance of the products obtained in Examples 1-5 and Comparative Examples 1-6 As shown in Table 1, the hydroxyl value, viscosity, and appearance indicators of the products produced in Examples 1-5 are qualified, and the reaction conversion rate is high, while the hydroxyl value and viscosity of the products obtained in Comparative Examples 1-6 are unqualified, and the reaction conversion rate is also low. This is because in Comparative Example 1, isomeric decanol is used to replace C8 alcohol. The carbon chain branching structure of the isomeric alcohol destroys the molecular regularity of the polyether polyol, resulting in enhanced intermolecular forces and a significant increase in viscosity. The branching structure may hinder the ring-opening polymerization reaction of the epoxide, reducing reaction efficiency and causing a decrease in the reaction conversion rate. In addition, the steric hindrance of the isomeric alcohol may cause uneven mixing of the raw materials, the production of byproducts during the reaction, and the appearance of the product is turbid and the color is darkened. Comparative Example 2 does not add the first catalyst. The first catalyst is a key component of the etherification reaction and is used to promote the hydroxyl conversion and etherification reaction of the fatty alcohol and polyol. The lack of the first catalyst will lead to incomplete etherification reaction, and a large amount of unreacted hydroxyl groups will remain in the system, resulting in a high hydroxyl value. Inadequately etherified raw material structures are difficult to react effectively with epoxides, resulting in a reduced degree of polymerization, molecular chain breakage, a significant decrease in reaction conversion, an increase in byproducts, and a turbid appearance. Comparative Example 3 did not add a second catalyst. The second catalyst is an initiator for the ring-opening polymerization reaction, used to activate the epoxy groups of the epoxide. Without a catalyst, the epoxide polymerization reaction hardly occurs, and a large amount of unreacted epoxide and alcohol ether raw materials remain, resulting in an extremely high hydroxyl value (excessive free hydroxyl groups), making the reaction impossible. The system is dominated by small molecules, and local overheating may cause side reactions (such as epoxide hydrolysis), resulting in colored impurities, a turbid appearance, and an extremely low reaction conversion. In Comparative Example 4, the second catalyst is excessive (the weight of sodium hydroxide is 2 parts, while the maximum weight of the second catalyst specified in the present invention is 1.5 parts). This excess second catalyst can lead to excessive polymerization of the epoxide, forming long-chain polymers with uneven molecular weight distribution, increased intermolecular entanglement, and a significant increase in viscosity. The strong alkaline environment may trigger side reactions (such as polyether chain breakage and oxidation), forming colored substances (such as aldehydes and ketones), causing the product to turn yellow. Excessive second catalyst is not fully neutralized, and residual residues may catalyze polyether degradation or hydrolysis, leading to system instability and a turbid appearance. In Comparative Example 5, no polyol was added. The role of the polyol is to provide a polyhydroxy structure, increase molecular branching, and reduce crystallinity. In the absence of a polyol, the fatty alcohol (monohydroxy) can only form linear polyether chains with the epoxide. These chains are highly regular and prone to crystallization, resulting in a sudden increase in viscosity. The lack of a branched structure can lead to insufficient hydrophilicity of the polyether, an imbalance in the HLB value, poor system compatibility, phase separation, and a turbid appearance. A linear structure can hinder mass transfer in the late stages of the reaction, leading to excessively high local concentrations of the epoxide, triggering side reactions, abnormal hydroxyl values, and a darker color.Comparative Example 6, without etherification, reacted directly with the epoxide. The unetherified fatty alcohol (monohydroxy) reacted directly with the epoxide, resulting in only a single-chain polyether with a low molecular weight, few functional groups, and a high hydroxyl value (a high proportion of free hydroxyl groups). The lack of an etherification step resulted in insufficient molecular branching, weak interchain interactions, and a tendency to form loosely entangled long chains, leading to abnormally high viscosity. Direct reaction can lead to uneven insertion of the epoxide, the formation of a large number of byproducts (such as cyclic ethers and dimers), and the system is high in impurities, resulting in a viscous appearance and darker color.

[0046] Application experiments were conducted on the products obtained in Examples 1-5 and Comparative Examples 1-6. The experimental methods were based on national standards or industry standards. The experimental results are shown in Table 2.

[0047] Table 2 Application test results of the products obtained in Examples 1-5 and Comparative Examples 1-6 As shown in Table 2, the surfactant polyether produced by the method of the present invention has excellent surface activity, low epoxide residue, high efficiency and low foaming properties, meeting current environmental protection requirements and meeting customers' cleaning requirements.

[0048] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made based on the essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-foaming surfactant polyether polyol, characterized in that: The main steps are as follows: Step 1: Weigh 138 parts of C8-C13 straight-chain fatty alcohol, 76-210 parts of polyol, 0.2 parts of the first catalyst, 1-1.5 parts of the second catalyst, 264-290 parts of epoxide and 1.5 parts of the post-treatment agent in parts by weight, and set aside; Step 2: placing a C8-C13 straight-chain fatty alcohol, a polyol, and a first catalyst in a high-pressure reactor with an external circulation device, stirring them uniformly, first performing hydroxyl conversion, and then performing an etherification reaction at a temperature of 140-240° C. and a vacuum degree controlled at -0.025 MPa for 4-6 hours to obtain an alcohol ether. After the etherification is completed, the small molecular substances produced in the reaction are removed; Step 3: Add the second catalyst to the autoclave, then continuously add the epoxide while stirring at a speed of 30-85 rpm, and undergo a ring-opening polymerization reaction at a temperature of 110-160° C. and a pressure of 0.1-0.3 MPa. The mixture is aged for 3-5 hours to produce a crude polyether polyol. When the cumulative amount of epoxide added reaches more than 20% of the total amount, the external circulation device is turned on to optimize mass and heat transfer to ensure continuous reaction. After step 4 and step 3 are completed, the pressure of the autoclave is discharged to 0 MPa, and a post-treatment agent is added to the autoclave for neutralization treatment to obtain the final product.

2. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein The C8-C13 straight-chain fatty alcohol is selected from C8 alcohol or C13 alcohol.

3. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein The polyol is selected from diol and / or triol.

4. The method for preparing a low-foaming surfactant polyether polyol according to claim 3, wherein: The polyol is selected from any one or more of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol.

5. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein: The first catalyst is zinc acetate or antimony trioxide.

6. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein: The second catalyst is selected from one or more of potassium hydroxide, sodium hydroxide, dodecyl tertiary amine, and tridecyl tertiary amine.

7. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein: The epoxide is one or more of ethylene oxide, propylene oxide, epichlorohydrin and butylene oxide.

8. The method for preparing a low-foaming surfactant polyether polyol according to claim 1, wherein: The post-treatment agent is at least one of glacial acetic acid, phosphoric acid and citric acid.

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