A compound surfactant and a preparation method thereof

Abstract

The present application relates to a kind of complex surfactants and its preparation method.A kind of complex surfactants, by the following components by weight parts: nonionic surfactant 40-70 parts, anionic surfactant 20-30 parts.A kind of complex surfactant preparation method, comprising the following steps: S1, the formula amount of polymerization monomer, formula amount of catalyst, formula amount of initiator are respectively dehydrated treatment;S2, after the dehydration treatment of catalyst, initiator in step S1 is added to reaction kettle, the polymerization monomer of dehydrated treatment in step S1 is added in portions, is reacted under nitrogen atmosphere, obtains nonionic surfactant;S3, formula amount of anionic surfactant is mixed with the nonionic surfactant of step S2 and is obtained, namely the complex surfactant of uniformity is obtained.The present application has the following beneficial effects: 1, reaction efficiency is high;2, can well reduce the molecular weight distribution of product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surfactants, in particular to a compound surfactant and a preparation method thereof. BACKGROUND

[0002] Since the advent of polyether polyols in the 1930s, it was first used as a non-ionic surfactant, and in the following decades, polyether polyols developed very rapidly, and currently the global polyether polyol has reached millions of tons of annual production capacity, and its application field is continuously expanding, becoming more and more important, only a small amount needs to be added in the process of product processing or manufacturing, and one or several functions can produce great effect and benefit.

[0003] Chinese patent CN103846082B discloses a mesoporous carbon composite metal oxide as a basic solid catalyst, which has a two-dimensional hexagonal mesostructure, and also has the characteristics of large specific surface area and uniform pore size distribution, and is used to catalyze ethoxylation reaction, compared with traditional ethoxylation catalyst strong base, has the advantages of narrow product distribution, high reaction conversion rate and high selectivity, easy post-processing, etc. However, the technical solution of the above patent still has the following shortcomings: it can only catalyze the ethoxylation reaction of low-carbon alcohol with carbon atom number less than 4, and the product is only fatty alcohol monoether, and the application range is narrow.

[0004] Chinese patent application CN109369903A discloses that an oxide of Zr is used as a catalyst carrier, then a promoter is added, and finally an alkali metal is loaded, and by this method, a fatty alcohol polyether with narrow distribution, low raw material residue and low PEG / PPG content can be prepared. However, the technical solution of the above patent still has the following shortcomings: the loading of the alkali metal on the catalyst carrier adopts the impregnation method, which increases the post-processing step, and at the same time, since the catalyst has only a surface layer, the activity of the catalyst will decrease sharply with the number of uses.

[0005] The surfactants on the market at present mainly include fatty alcohol polyoxyethylene ethers, which have good comprehensive properties such as diffusion, uniform dyeing, wetting, foaming, etc., but strong base catalysts are used in the preparation process, and there are disadvantages such as poor flow performance, uneven diffusion, and narrow application range. SUMMARY

[0006] The present application provides a compound surfactant and a preparation method thereof, which solves the problems of the prior art. The present application selects long-chain multi-fatty alcohol as a starter, and ethylene oxide and propylene oxide as reaction monomers to prepare a non-ionic surfactant with narrow molecular weight distribution and high surface activity, and further enhances the emulsifying performance of the surfactant by compounding with a specific proportion of anionic surfactant.

[0007] Technical solution: A compound surfactant, by weight parts, consists of: non-ionic surfactant 40-70 parts, anionic surfactant 20-30 parts, preferably non-ionic surfactant 40-60 parts, anionic surfactant 20-25 parts.

[0008] Further, the anionic surfactant is at least one of ammonium stearate, sodium stearate, sodium n-dodecyl sulfonate (CAS: 2386-53-0), sodium alkyl aryl sulfonate, sodium alkyl sulfate.

[0009] Further, the anionic surfactant is a mixture of sodium n-dodecyl sulfonate and ammonium stearate, and the weight ratio of sodium n-dodecyl sulfonate to ammonium stearate is 1:(2-5), preferably 1:2.5.

[0010] Further, the sodium alkyl aryl sulfonate is one of C10-C18 sodium benzene sulfonate or C10-C18 sodium naphthalene sulfonate.

[0011] Further, the sodium alkyl sulfate is one of sodium dodecyl sulfate, sodium tridecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate.

[0012] Further, the non-ionic surfactant consists of: initiator, polymerized monomer, catalyst, wherein:

[0013] The molar ratio of the initiator to the polymerized monomer is 1:(40-60), preferably 1:45;

[0014] The catalyst accounts for 0.1-0.5wt% of the total weight of the polymerized monomer, preferably 0.15-0.4wt%, and most preferably 0.18wt% by mass percentage.

[0015] Further, the initiator is at least one of dodecanediol (CAS: 5675-51-4), 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol (CAS: 3155-43-9).

[0016] Further, the initiator is a mixture of dodecanediol and 1,18-octadecanediol, and the weight ratio of dodecanediol to 1,18-octadecanediol is 1:(1-3), preferably 1:3.

[0017] Further, the catalyst is a double metal cyanide catalyst, which is purchased from Shanghai Qikeliu Fluorine Silicon Material Co., Ltd., model: DMC-001.

[0018] Further, the polymerization monomers are ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide to propylene oxide is 1:(0.05-0.2), preferably 1:0.1.

[0019] A preparation method of the above-mentioned complex surfactant comprises the following steps:

[0020] S1, the formula amount of polymerization monomer, the formula amount of catalyst, the formula amount of initiator are respectively dehydrated;

[0021] S2, the catalyst and initiator after the dehydration treatment in step S1 are added to the reaction kettle, and the polymerization monomer after the dehydration treatment in step S1 is added in several times, and the reaction is carried out under the atmosphere of nitrogen to obtain the non-ionic surfactant;

[0022] S3, the formula amount of anionic surfactant is mixed with the non-ionic surfactant obtained in step S2 to obtain the complex surfactant.

[0023] Further, in step S2, the catalyst and initiator after the dehydration treatment in step S1 are added to the reaction kettle, and 30-40wt% of the polymerization monomer after the dehydration treatment in step S1 is added first, and the first reaction is carried out under the atmosphere of nitrogen, and when the pressure rises to 0.8-1.2MPa, the remaining polymerization monomer after the dehydration treatment in step S1 is added to continue the second reaction for 1-2h to obtain the non-ionic surfactant.

[0024] Further, the reaction temperature of the first reaction in step S2 is 80-115℃, preferably 90-100℃.

[0025] Further, the reaction temperature of the second reaction in step S2 is 110-145℃, preferably 120-135℃, and most preferably 128℃.

[0026] The reaction pressure of the second reaction in step S2 is 0.5-1.5MPa, preferably 1-1.5MPa, and most preferably 1.05MPa.

[0027] Beneficial effects: the complex surfactant and the preparation method thereof disclosed by the application have the following beneficial effects:

[0028] 1. High reaction efficiency - the molar ratio of the initiator to the polymerization monomer is controlled to be 1:(40-60), the reaction temperature of the second reaction is controlled to be 110-145℃, and the pressure of the second reaction is controlled to be 0.5-1.5MPa, which can improve the reaction efficiency.

[0029] 2. The product molecular weight distribution can be well reduced - by adding 30-40wt% of the polymerization monomer first, and carrying out the reaction under nitrogen atmosphere, when the pressure rises to 0.8-1.2MPa, adding the rest of the polymerization monomer can well reduce the product molecular weight distribution. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application are described in detail below.

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values should be interpreted as approximately between the stated values and include values proximate the stated values. For values having an increment, the increments between the stated values, between the stated values and the individual values, and between the individual values should be understood as being included in the text.

[0032] The inventor found that when the molar ratio of initiator to polymerization monomer is 1:(40-60), the reaction efficiency can be improved, and as the amount of polymerization monomer increases, the highest temperature reached in the reactor is higher, the induction period temperature is lower, the induction time is shorter, and the reaction is faster. The reason is that at a higher temperature, the more polymerization monomer, the more gas molecules per unit volume, so the more contact probability of monomer and initiator molecules per unit volume. When the molecules absorb energy and change from normal molecules to activated molecules, the effective collision between molecules will increase, so the reaction occurs in a short time, and once the reaction occurs, the released heat will further intensify the reaction, and the reaction can be completed rapidly. Because the more molecules participating in the reaction per unit time, the more intense the reaction, the more heat released, and at too high a temperature, not only can the reaction rate not be further improved to improve product quality, but also the increase of by-products and the waste of resources. At the same time, too high a temperature will also cause safety problems.

[0033] The inventors found that the reaction efficiency can be improved when the temperature of the second reaction is 110-145℃ and the pressure of the second reaction is 0.5-1.5 MPa. When the temperature is lower, the reaction lasts longer and the maximum pressure reached is smaller. With the increase of the temperature, the maximum pressure in the reactor increases. This is because at a relatively low temperature and in a limited space, a small amount of liquid propylene oxide does not change into gas, and the pressure is small. With the increase of the temperature, a small amount of liquid propylene oxide begins to change into gas, and the pressure begins to increase. Since the amount of propylene oxide is constant, the pressure has a maximum value. When the temperature reaches 128℃, the induction time of the reaction is the shortest and the reaction is the fastest. This is because at this temperature, the gas pressure in the reaction system is in a suitable range, and the effective collision between molecules is more likely to occur, so the reaction can be activated in a short time and proceed rapidly. Further research found that adding the polymerization monomer in batches can reduce the molecular weight distribution of the product, which may be due to the control of the stable increase of the temperature of the reaction system and the maintenance of the temperature near 128℃ for a long time.

[0034] Example 1

[0035] The complex surfactant comprises, by weight parts, 50 parts of non-ionic surfactant and 22 parts of anionic surfactant.

[0036] Further, the anionic surfactant is a mixture of sodium n-dodecyl sulfonate (CAS: 2386-53-0) and ammonium stearate, and the weight ratio of the sodium alkyl sulfonate to the ammonium stearate is 1:2.5.

[0037] The non-ionic surfactant is composed of a starter, a polymerization monomer and a catalyst, wherein:

[0038] The molar ratio of the starter to the polymerization monomer is 1:45;

[0039] The catalyst accounts for 0.18wt% of the polymerization monomer in terms of mass percentage.

[0040] The starter is a mixture of dodecanediol (CAS: 5675-51-4) and 1,18-octadecanediol (CAS: 3155-43-9), and the weight ratio of the dodecanediol to the 1,18-octadecanediol is 1:3.

[0041] The catalyst is a double-metal cyanide catalyst, which is purchased from Shanghai Qikeliu Silica Material Co., Ltd. and the model number is DMC-001.

[0042] The polymerization monomer is a mixture of ethylene oxide and propylene oxide, and the molar ratio of the ethylene oxide to the propylene oxide is 1:0.1.

[0043] A preparation method of the above-mentioned complex surfactant, comprising the following steps:

[0044] S1, the formula amount of polymerization monomer, the formula amount of catalyst, the formula amount of initiator are respectively dehydrated;

[0045] S2, the catalyst and initiator after dehydration treatment in step S1 are added to a reaction kettle, 35wt% of the polymerization monomer is first added, and the first reaction is carried out under a nitrogen atmosphere, when the pressure of the reaction kettle rises to 0.8MPa, the remaining polymerization monomer is added to continue the second reaction for 1.5h, and a nonionic surfactant is obtained;

[0046] S3, the formula amount of anionic surfactant is mixed with the nonionic surfactant obtained in step S2, and the complex surfactant is obtained.

[0047] Further, the reaction temperature of the first reaction in step S2 is 95℃.

[0048] Further, the reaction temperature of the second reaction in step S2 is 128℃, and the reaction pressure of the second reaction in step S2 is 1.05MPa.

[0049] Example 2

[0050] The preparation method is substantially the same as that of example 1, and the only difference is that the molar ratio of the initiator to the polymerization monomer is 1:50.

[0051] Example 3

[0052] The preparation method is substantially the same as that of example 1, and the only difference is that the specific process parameters of the preparation method are different:

[0053] A preparation method of the above-mentioned complex surfactant, comprising the following steps:

[0054] S1, the formula amount of polymerization monomer, the formula amount of catalyst, the formula amount of initiator are respectively dehydrated;

[0055] S2, the catalyst and initiator after dehydration treatment in step S1 are added to a reaction kettle, 40wt% of the polymerization monomer is first added, and the first reaction is carried out under a nitrogen atmosphere, when the pressure of the reaction kettle rises to 0.8MPa, the remaining polymerization monomer is added to continue the second reaction for 1h, and a nonionic surfactant is obtained;

[0056] S3, the formula amount of anionic surfactant is mixed with the nonionic surfactant obtained in step S2, and the complex surfactant is obtained.

[0057] Example 4

[0058] A compound surfactant, consisting of the following components by weight: non-ionic surfactant 40 parts, anionic surfactant 20 parts.

[0059] Further, the anionic surfactant is ammonium stearate.

[0060] Further, the non-ionic surfactant consists of the following components: initiator, polymerization monomer, catalyst, wherein:

[0061] The molar ratio of the initiator to the polymerization monomer is 1:40;

[0062] The catalyst accounts for 0.1 of the total weight of the polymerization monomer in mass percentage.

[0063] In another embodiment, the non-ionic surfactant consists of the following components: initiator, polymerization monomer, catalyst, wherein:

[0064] The molar ratio of the initiator to the polymerization monomer is 1:40;

[0065] The catalyst accounts for 0.15 of the total weight of the polymerization monomer in mass percentage.

[0066] Further, the initiator is dodecanediol (CAS: 5675-51-4).

[0067] Further, the catalyst is a double metal cyanide catalyst, available from Shanghai Qikeli Fluorine Silicon Material Co., Ltd., model: DMC-001.

[0068] Further, the polymerization monomer is ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide to propylene oxide is 1:0.05.

[0069] A preparation method of the above-mentioned compound surfactant, comprising the following steps:

[0070] S1, the formula amount of the polymerization monomer, the formula amount of the catalyst, and the formula amount of the initiator are respectively subjected to dehydration treatment;

[0071] S2, the catalyst and the initiator subjected to dehydration treatment in step S1 are added to a reaction kettle, and the polymerization monomer subjected to dehydration treatment in step S1 is added in portions, and the reaction is carried out under a nitrogen atmosphere to obtain a non-ionic surfactant;

[0072] S3, the formula amount of the anionic surfactant is uniformly mixed with the non-ionic surfactant obtained in step S2 to obtain a compound surfactant.

[0073] Further, in step S2, the catalyst and initiator after the dehydration treatment in step S1 are added into the reactor, 30wt% of the polymerized monomers after the dehydration treatment in step S1 are added first, and the first reaction is carried out under a nitrogen atmosphere. When the pressure rises to 0.8MPa, the remaining polymerized monomers after the dehydration treatment in step S1 are added to continue the second reaction for 2h, to obtain the nonionic surfactant.

[0074] Further, the reaction temperature of the first reaction in step S2 is 80℃.

[0075] In another embodiment, the reaction temperature of the first reaction in step S2 is 90℃.

[0076] Further, the reaction temperature of the second reaction in step S2 is 110℃, and the reaction pressure of the second reaction in step S2 is 0.5MPa.

[0077] In another embodiment, the reaction temperature of the second reaction in step S2 is 120℃, and the reaction pressure of the second reaction in step S2 is 1MPa.

[0078] Embodiment 5

[0079] A compounded surfactant, consisting of the following components in parts by weight: nonionic surfactant 70 parts, anionic surfactant 30 parts.

[0080] In another embodiment, a compounded surfactant, consisting of the following components in parts by weight: nonionic surfactant 60 parts, anionic surfactant 25 parts.

[0081] Further, the anionic surfactant is sodium stearate.

[0082] Further, the nonionic surfactant consists of the following components: initiator, polymerized monomers, catalyst, wherein:

[0083] The molar ratio of the initiator to the polymerized monomers is 1:60;

[0084] The catalyst accounts for 0.5wt% of the total weight of the polymerized monomers in mass percentage.

[0085] In another embodiment, the nonionic surfactant consists of the following components: initiator, polymerized monomers, catalyst, wherein:

[0086] The molar ratio of the initiator to the polymerized monomers is 1:60;

[0087] The catalyst accounts for 0.4wt% of the total weight of the polymerized monomers in mass percentage.

[0088] Further, the initiator is 1,14-tetradecanediol.

[0089] Further, the catalyst is a double metal cyanide catalyst, which is purchased from Shanghai Qike Fluorine Silicon Material Co., Ltd., model: DMC-001.

[0090] Further, the polymerization monomer is ethylene oxide and propylene oxide, and the molar ratio of the ethylene oxide to the propylene oxide is 1:0.2.

[0091] A preparation method of the above-mentioned complex surfactant, comprising the following steps:

[0092] S1, the formula amount of the polymerization monomer, the formula amount of the catalyst, and the formula amount of the initiator are respectively subjected to dehydration treatment;

[0093] S2, the catalyst and the initiator subjected to the dehydration treatment in step S1 are added into a reaction kettle, the polymerization monomer subjected to the dehydration treatment in step S1 is added in portions, and a reaction is carried out under a nitrogen atmosphere to obtain a non-ionic surfactant;

[0094] S3, the formula amount of the anionic surfactant is uniformly mixed with the non-ionic surfactant obtained in step S2 to obtain a complex surfactant.

[0095] Further, in step S2, the catalyst and the initiator subjected to the dehydration treatment in step S1 are added into a reaction kettle, 40wt% of the polymerization monomer subjected to the dehydration treatment in step S1 is first added, a first reaction is carried out under a nitrogen atmosphere, when the pressure is increased to 1.2MPa, the remaining polymerization monomer subjected to the dehydration treatment in step S1 is added to continue a second reaction for 1h to obtain a non-ionic surfactant.

[0096] Further, the reaction temperature of the first reaction in step S2 is 115℃.

[0097] In another embodiment, the reaction temperature of the first reaction in step S2 is 100℃.

[0098] Further, the reaction temperature of the second reaction in step S2 is 145℃, and the reaction pressure of the second reaction in step S2 is 1.5MPa.

[0099] In another embodiment, the reaction temperature of the second reaction in step S2 is 135℃, and the reaction pressure of the second reaction in step S2 is 1.5MPa.

[0100] Example 6

[0101] A complex surfactant, consisting of the following components in parts by weight: 46 parts of a non-ionic surfactant and 23 parts of an anionic surfactant.

[0102] Further, the anionic surfactant is sodium n-dodecyl sulfonate (CAS: 2386-53-0).

[0103] Further, the non-ionic surfactant consists of a starter, a polymerized monomer, a catalyst, wherein:

[0104] The molar ratio of the starter to the polymerized monomer is 1:45;

[0105] The catalyst accounts for 0.18wt% of the total weight of the polymerized monomer in terms of mass percentage.

[0106] Further, the starter is 1,16-hexadecanediol.

[0107] Further, the catalyst is a double metal cyanide catalyst, which is purchased from Shanghai Qikeli Fluorine Silicon Material Co., Ltd., model: DMC-001.

[0108] Further, the polymerized monomer is ethylene oxide and propylene oxide, and the molar ratio of the ethylene oxide to the propylene oxide is 1:0.1.

[0109] A preparation method of the above-mentioned compounded surfactant, comprising the following steps:

[0110] S1, respectively dehydrate the formula amount of the polymerized monomer, the formula amount of the catalyst, and the formula amount of the starter;

[0111] S2, add the catalyst and the starter dehydrated in step S1 into a reaction kettle, add the polymerized monomer dehydrated in step S1 in portions, and carry out a reaction under a nitrogen atmosphere to obtain a non-ionic surfactant;

[0112] S3, mix the formula amount of the anionic surfactant with the non-ionic surfactant obtained in step S2 uniformly to obtain a compounded surfactant.

[0113] Further, in step S2, after the catalyst and the starter dehydrated in step S1 are added into a reaction kettle, 35wt% of the polymerized monomer dehydrated in step S1 is first added, a first reaction is carried out under a nitrogen atmosphere, when the pressure rises to 1MPa, the remaining polymerized monomer dehydrated in step S1 is added to continue a second reaction for 1.5h to obtain a non-ionic surfactant.

[0114] Further, the reaction temperature of the first reaction in step S2 is 95℃.

[0115] Further, the reaction temperature of the second reaction in step S2 is 128℃.

[0116] The reaction pressure of the second reaction in step S2 is 1.05 MPa.

[0117] Examples 7-31

[0118] The same as Example 4, except that the anionic surfactant is different:

[0119]

[0120]

[0121] Examples 32-37 are the same as Example 4, except that the initiator is different:

[0122]

[0123] Comparative Example 1

[0124] The same as Example 1, except that the molar ratio of the initiator to the polymerization monomer is 1:30.

[0125] Comparative Example 2

[0126] The same as Example 1, except that the reaction temperature of the second reaction is 110°C and the reaction pressure of the second reaction is 0.7 MPa.

[0127] Comparative Example 3

[0128] The same as Example 1, except that the specific process parameters of the preparation method are different:

[0129] A preparation method of the above-mentioned compounded surfactant, comprising the following steps:

[0130] S1, dehydrate the formula amount of polymerization monomer, the formula amount of catalyst, and the formula amount of initiator, respectively;

[0131] S2, add the catalyst, initiator, and polymerization monomer after dehydrating treatment in step S1 into a reaction kettle, and carry out reaction under nitrogen atmosphere at a pressure of 1.05 MPa, a reaction temperature of 128°C, and a reaction time of 1.5 h. After the reaction is completed, a non-ionic surfactant is obtained;

[0132] S3, mix the formula amount of anionic surfactant with the non-ionic surfactant obtained in step S2 uniformly, and a compounded surfactant is obtained.

[0133] Performance test method

[0134] 1) The non-ionic surfactants prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to GPC (gel permeation chromatography) test for molecular weight distribution, and the test data are shown in Table 1.

[0135] 2) The surface activity of the composite surfactants prepared in Examples 1-3 and Comparative Examples 1-3 were tested by the pull-off method and the surface tension of their aqueous solutions was measured. The test data are shown in Table 1.

[0136] Performance test data

[0137] Table 1

[0138] Molecular weight distribution Surface tension mN / m Example 1 1.12 20.5 Example 2 1.13 21.6 Example 3 1.16 21.4 Comparative Example 1 1.31 27.1 Comparative Example 2 1.29 26.5 Comparative Example 3 1.34 26.5

[0139] As can be seen from Table 1, the surface tension of Examples 1-3 is reduced by about 25% relative to Comparative Examples 1-3, and the molecular weight distribution of the products of Examples 1-3 is also greatly reduced relative to Comparative Examples 1-3.

[0140] The above detailed the embodiments of the present application. However, the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A compound surfactant, characterized in that, By weight, it consists of the following components: 40-70 parts nonionic surfactant and 20-30 parts anionic surfactant, wherein: The anionic surfactant is at least one of ammonium stearate, sodium stearate, sodium dodecyl sulfonate, sodium alkyl aryl sulfonate, and sodium alkyl sulfate. The nonionic surfactant is composed of the following components: initiator, polymerizing monomer, and catalyst, wherein: The molar ratio of the initiator to the polymerizing monomer is 1:(40-60); The catalyst accounts for 0.1 wt% to 0.5 wt% of the total weight of the polymerizing monomers by mass percentage; The initiator is at least one selected from dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, and 1,18-octadecanediol; The catalyst is a bimetallic cyanide catalyst; The polymerization monomers are ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide to propylene oxide is 1:(0.05-0.2). The nonionic surfactant is prepared by the following steps: S1. Dehydrate the formulated amounts of monomer, catalyst, and initiator respectively. S2. The catalyst and initiator, after dehydration treatment in step S1, are added to the reactor. First, 30-40 wt% of the polymerizable monomers after dehydration treatment in step S1 are added, and the first reaction is carried out under a nitrogen atmosphere. When the pressure rises to 0.8-1.2 MPa, the remaining polymerizable monomers after dehydration treatment in step S1 are added, and the second reaction is continued for 1-2 hours to obtain a nonionic surfactant, wherein: The reaction temperature of the first reaction in step S2 is 80-115℃; The reaction temperature of the second reaction in step S2 is 110-145℃; The reaction pressure of the second reaction in step S2 is 0.5-1.5 MPa.

2. The compound surfactant as described in claim 1, characterized in that, The compound surfactant is composed of the following components: by weight, 40-60 parts of nonionic surfactant and 20-25 parts of anionic surfactant.

3. A compound surfactant as described in claim 2, characterized in that, The anionic surfactant is a mixture of sodium dodecyl sulfonate and ammonium stearate, wherein the weight ratio of sodium dodecyl sulfonate to ammonium stearate is 1:(2-5).

4. A compound surfactant as described in claim 3, characterized in that, The anionic surfactant is a mixture of sodium dodecyl sulfonate and ammonium stearate, wherein the weight ratio of sodium dodecyl sulfonate to ammonium stearate is 1:2.

5.

5. A compound surfactant as described in claim 1, characterized in that, The alkylaryl sulfonate sodium is one of C10-C18 benzenesulfonate sodium or C10-C18 naphthalenesulfonate sodium.

6. A compound surfactant as described in claim 1, characterized in that, The sodium alkyl sulfate is one of sodium dodecyl sulfate, sodium tridecyl sulfate, sodium tetradecyl sulfate, and sodium pentadecyl sulfate.

7. A compound surfactant as described in claim 1, characterized in that, The nonionic surfactant is composed of the following components: initiator, polymerizing monomer, and catalyst, wherein: The molar ratio of the initiator to the polymerizing monomer is 1:45; The catalyst accounts for 0.15 wt% to 0.4 wt% of the total weight of the polymerizing monomers by mass percentage.

8. A compound surfactant as described in claim 1, characterized in that, The initiator is a mixture of dodecanediol and 1,18-octadecanediol, wherein the weight ratio of dodecanediol to 1,18-octadecanediol is 1:(1-3).

9. A compound surfactant as described in claim 8, characterized in that, The initiator is a mixture of dodecanediol and 1,18-octadecanediol, wherein the weight ratio of dodecanediol to 1,18-octadecanediol is 1:

3.

10. A compound surfactant as described in claim 1, characterized in that, The polymerization monomers are ethylene oxide and propylene oxide, and the molar ratio of ethylene oxide to propylene oxide is 1:0.

1.

11. A method for preparing a compound surfactant according to any one of claims 1-10, characterized in that, Includes the following steps: S1. Dehydrate the formulated amounts of monomer, catalyst, and initiator respectively. S2. The catalyst and initiator, after dehydration treatment in step S1, are added to the reactor. First, 30-40 wt% of the polymerizable monomers after dehydration treatment in step S1 are added, and the first reaction is carried out under a nitrogen atmosphere. When the pressure rises to 0.8-1.2 MPa, the remaining polymerizable monomers after dehydration treatment in step S1 are added, and the second reaction is continued for 1-2 hours to obtain a nonionic surfactant, wherein: The reaction temperature of the first reaction in step S2 is 80-115℃; The reaction temperature of the second reaction in step S2 is 110-145℃; In step S2, the reaction pressure of the second reaction is 0.5-1.5 MPa; S3. Mix the formulated amount of anionic surfactant with the nonionic surfactant obtained in step S2 until homogeneous to obtain the compound surfactant.

12. The method for preparing the compound surfactant as described in claim 11, characterized in that, The reaction temperature of the first reaction in step S2 is 90-100℃.

13. The method for preparing the compound surfactant as described in claim 11, characterized in that, The reaction temperature of the second reaction in step S2 is 120-135℃; The reaction pressure of the second reaction in step S2 is 1-1.5 MPa.

14. The method for preparing the compound surfactant as described in claim 13, characterized in that, The reaction temperature of the second reaction in step S2 is 128°C; The reaction pressure of the second reaction in step S2 is 1.05 MPa.

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