An emulsion type silicone defoamer, a preparation method and application thereof

Abstract

The application discloses an emulsion type silicone defoamer and a preparation method and application thereof. The emulsion type silicone defoamer comprises silicone, and the defoamer further comprises a heat-resistant modifier, wherein the heat-resistant modifier comprises sodium lignosulfonate and carboxymethyl cellulose ether; the mass ratio of the sodium lignosulfonate and the carboxymethyl cellulose ether is 0.4-68:1; and the pH value of the defoamer is 5-9. By simultaneously using the sodium lignosulfonate and the carboxymethyl cellulose ether in the emulsion type silicone defoamer and controlling the mass ratio of the two within a specific range, the sodium lignosulfonate and the carboxymethyl cellulose ether can produce a synergistic effect, the heat stability of the silicone defoamer is significantly improved, the defoamer does not precipitate silicone after long-term storage at high temperature, the defoaming performance of the defoamer does not decrease obviously at high temperature, and the defoamer can still effectively defoam.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone defoaming agent, in particular to an emulsion type silicone defoaming agent, a preparation method and application thereof. BACKGROUND

[0002] Among many defoaming agents such as silicone defoaming agent, polyether defoaming agent, mineral oil defoaming agent and the like, the silicone defoaming agent is popular due to its moderate price, unique chemical structure and excellent / rapid defoaming ability. However, the defoaming agent is unstable during use and storage, especially under heat. The defoaming performance of the defoaming agent is significantly reduced after storage under heat (e.g. 50-100℃), and even the defoaming ability is completely lost.

[0003] In order to improve the thermal stability of the silicone defoaming agent, the prior art usually synthesizes a new structure of silicone compound, and / or adjusts the formula of the silicone defoaming agent.

[0004] Patent CN118954680A discloses that dimethyl dimethoxysilane, methyl phenyl siloxane and cyclic silicon are first synthesized into modified polysiloxane by polymerization, and then other additives such as emulsifier, surface tension regulator, stabilizer and thickening agent are added into the defoaming agent composition formula, so as to achieve high temperature resistance of 121℃. Patent CN108339296B discloses that vinyl silicone oil, allyl polyether and sodium allyl sulfonate are mixed and then copolymerized, and then the copolymer is mixed with dimethyl silicone oil, so as to promote the defoaming performance and realize self-emulsification in water. The obtained defoaming agent can be stored under boiling condition. Patent CN111116863B discloses that acetylene diol / derivative thereof, allyl polyether and hydrogen-containing silicone oil are reacted, and then the generated intermediate is polymerized with specific isocyanate to generate a high molecular silicone defoaming agent containing polyurethane functional groups in the molecular chain. The defoaming agent can be stably stored at 50℃ for 14 days, and the defoaming property is almost unchanged. However, in the above patents, the steps of synthesizing new structure of silicone are complex, difficult to industrialize and high in cost.

[0005] The existing patents for adjusting the formula of the silicone defoaming agent can improve the stability of the silicone defoaming agent, but the improvement degree is not enough. The thermal stability of the silicone defoaming agent is not high enough. The silicone defoaming agent is prone to precipitate silicone under high temperature, and the defoaming performance is also significantly reduced. SUMMARY

[0006] In view of the shortcomings and deficiencies of the prior art, the present application provides an improved emulsion type silicone defoaming agent. The thermal stability of the defoaming agent is significantly improved. The defoaming agent does not precipitate silicone after high temperature storage, and the defoaming performance is not significantly reduced under high temperature. The defoaming agent can still effectively defoam. Moreover, the defoaming agent does not involve complex preparation process, is easy to industrialize and low in cost.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] An emulsion type silicone defoamer, comprising silicone, the defoamer further comprising a heat-resistant modifier, the heat-resistant modifier comprising sodium lignosulfonate and carboxymethyl cellulose ether; the mass ratio of the sodium lignosulfonate and the carboxymethyl cellulose ether being 0.4-68:1; the pH value of the defoamer being 5-9.

[0009] In some embodiments, the mass ratio of the sodium lignosulfonate and the carboxymethyl cellulose ether is 1-8:1. Within this mass ratio range, the high-temperature stability and defoaming performance of the silicone defoamer can be further improved.

[0010] In some embodiments, the mass ratio of the sodium lignosulfonate and the silicone is 0.04-1:1.

[0011] In some embodiments, the silicone is polydimethylsiloxane. The present application can not perform complex structural modification on the silicone molecules.

[0012] In some embodiments, the defoamer further comprises an anionic emulsifier and a nonionic emulsifier.

[0013] In some embodiments, the anionic emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polycarboxylate and sodium polyacrylate.

[0014] In some embodiments, the nonionic emulsifier is selected from at least one of fatty alcohol polyoxyethylene ether, Tween and Span.

[0015] In some embodiments, the fatty alcohol polyoxyethylene ether includes isomeric alcohol polyoxyethylene ether. Specifically, the fatty alcohol polyoxyethylene ether can be fatty alcohol polyoxyethylene ether AEO-9, and the isomeric alcohol polyoxyethylene ether can be isomeric decanol polyoxyethylene ether, isomeric undecanol polyoxyethylene ether, isomeric tridecanol polyoxyethylene ether, etc.

[0016] In some embodiments, the mass ratio of the anionic emulsifier and the nonionic emulsifier is 0.5-0.8:1.

[0017] In some embodiments, the defoamer further comprises at least one of a cosolvent, a thickening agent, a pH regulator.

[0018] In some embodiments, the cosolvent is selected from at least one of isopropyl alcohol, ethanol, ethylene glycol, n-propanol.

[0019] In some embodiments, the thickening agent is selected from at least one of fumed silica and bentonite.

[0020] In some embodiments, the pH regulator is selected from sulfuric acid, hydrochloric acid, citric acid, triethanolamine or ammonia.

[0021] In some embodiments, the defoaming agent comprises polydimethylsiloxane, sodium lignosulfonate, carboxymethyl cellulose ether, an anionic emulsifier, a non-ionic emulsifier, a cosolvent, a thickening agent, a pH regulator and water.

[0022] In some embodiments, the defoaming agent comprises, in parts by weight, 20-30 parts of polydimethylsiloxane, 0.5-30 parts of sodium lignosulfonate, 0.1-10 parts of carboxymethyl cellulose ether, 1-5 parts of an anionic emulsifier, 1-5 parts of a non-ionic emulsifier, 3-10 parts of a cosolvent, 0.1-0.8 parts of a thickening agent, 55-65 parts of water, and the pH regulator is used in an amount such that the pH value of the defoaming agent is 5-9.

[0023] In some embodiments, the defoaming agent comprises, in parts by weight, 22-26 parts of polydimethylsiloxane, 1-20 parts of sodium lignosulfonate, 0.2-5 parts of carboxymethyl cellulose ether, 1-3 parts of an anionic emulsifier, 2-4 parts of a non-ionic emulsifier, 4-6 parts of a cosolvent, 0.1-0.3 parts of a thickening agent, 63-65 parts of water, and the pH regulator is used in an amount such that the pH value of the defoaming agent is 5-9.

[0024] In some embodiments, the pH value of the defoaming agent is 6-8.

[0025] In some embodiments, the viscosity of the defoaming agent at 20℃ is 100-300 mPa·s.

[0026] The present application also provides a preparation method of the aforementioned emulsion type silicone defoaming agent, comprising the following steps: 1) mixing and dispersing silicone, an anionic emulsifier, a non-ionic emulsifier and water to obtain a mixed solution; 2) heating the mixed solution, then adding a cosolvent, a thickening agent, sodium lignosulfonate and carboxymethyl cellulose ether, stirring and dispersing, and then adding a pH regulator to obtain the emulsion type silicone defoaming agent.

[0027] In some embodiments, in step 2), the temperature is raised to 40-80℃.

[0028] The present application also provides a use of the aforementioned emulsion type silicone defoaming agent for defoaming of glufosinate-ammonium aqueous agent.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The thermal stability of the emulsion type silicone defoaming agent of the present application is significantly improved, the defoaming agent does not precipitate silicone after long-term storage at high temperature, and the defoaming performance does not decrease significantly at high temperature, and the defoaming agent can still effectively defoam.

[0031] The emulsion type silicone defoamer of the present application can use conventional silicone components without complex modification of the chemical structure of the silicone components, thus the preparation process is simple, easy to industrialize, and low in cost. DETAILED DESCRIPTION

[0032] In the prior art, new structures of silicone compounds are usually synthesized to improve the thermal stability of silicone defoamers. Although the existing patents for adjusting the formula of silicone defoamers can also improve the stability of silicone defoamers to some extent, the improvement is not enough, the thermal stability of silicone defoamers is not high enough, and silicone defoamers are prone to precipitate silicone at high temperatures, and the defoaming performance also decreases significantly.

[0033] The innovation of the present application is that by simultaneously using sodium lignosulfonate LS and carboxymethyl cellulose ether CMC in the silicone defoamer emulsion and controlling the mass ratio of the two within a specific range, the two can produce a synergistic effect, ultimately making the defoamer emulsion stable at high temperatures, without precipitation of silicone, and after long-term storage at high temperatures, the defoaming performance of the defoamer emulsion does not decrease significantly, and it can still effectively defoam.

[0034] Sodium lignosulfonate LS has excellent water solubility and can be stably dissolved in water, and it has a rich aromatic ring structure in its chemical structure, so it has excellent heat resistance, for example, the lignin structure part of sodium lignosulfonate LS will hardly depolymerize at 200℃ or below.

[0035] Firstly, sodium lignosulfonate LS is added to the defoamer emulsion, which can wrap the silicone components in the silicone emulsion, and then use its own heat resistance to improve the thermal stability of the defoamer emulsion, so that the silicone components will not precipitate at high temperatures, and then the defoamer emulsion still has good defoaming performance after storage at high temperatures. Secondly, sodium lignosulfonate LS has various polar functional groups such as phenolic hydroxyl, aliphatic hydroxyl, ether bond, sulfonic acid group, etc. These polar functional groups, on the one hand, make it have excellent water solubility, and on the other hand, are also conducive to the interaction and combination between them and the polar functional groups in the anionic emulsifier and non-ionic emulsifier in the defoamer emulsion through hydrogen bonds, van der Waals forces, etc. The sulfonic acid group in LS has a charge, which can electrostatically adsorb the polydimethylsiloxane part in the defoamer emulsion, further improving the thermal stability of the silicone emulsion (not easy to break), and the silicone is not easy to precipitate at high temperatures. Finally, the rich benzene ring structure in sodium lignosulfonate LS can produce steric hindrance effect, so that the silicone molecules are not easy to collide with each other at high temperatures, and thus the precipitation problem of silicone due to increased molecular motion at high temperatures is inhibited.

[0036] However, if sodium lignosulfonate LS is used alone, it is easy to fall off from the surface of the silicone molecule due to its large molecule, resulting in that it cannot effectively and stably wrap the silicone molecule for a long time, and further adding carboxymethyl cellulose ether CMC in the defoaming agent emulsion, since sodium lignosulfonate LS and carboxymethyl cellulose ether CMC have natural good affinity (because lignin and cellulose are both main components of plant cell wall, and the two can be tightly combined, and LS has lignin part and CMC has cellulose part, so LS and CMC can be tightly combined), and multiple carboxyl groups exist in the chemical structure of CMC, which can also electrostatically adsorb polydimethylsiloxane molecules, and the electrostatic adsorption is stronger than that between sodium lignosulfonate LS and polydimethylsiloxane. Therefore, by adding CMC, the connection between the silicone molecule and sodium lignosulfonate LS can be strengthened, and finally the silicone molecule, sodium lignosulfonate and carboxymethyl cellulose ether CMC are tightly combined, the sodium lignosulfonate stably wraps the silicone molecule, and the stability and defoaming performance of the defoaming emulsion after high-temperature storage are significantly improved.

[0037] When the mass ratio of sodium lignosulfonate LS and carboxymethyl cellulose ether CMC is too high or too low, the synergistic effect of the two cannot be exerted.

[0038] The application will be further described below in conjunction with examples. However, the application is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions not mentioned are conventional conditions in the industry. The technical features involved in each embodiment of the application can be combined with each other as long as there is no conflict between them.

[0039] The pH adjuster in the examples and comparative examples is citric acid (0.5% by mass) and / or triethanolamine (0.5% by mass), which is slowly adjusted according to the target pH. Example 1

[0040] This embodiment provides a silicone defoaming agent emulsion, and the preparation process is as follows:

[0041] The polydimethylsiloxane, sodium dodecyl sulfate, Tween 80 and deionized water are mixed and dispersed, and stirred to be heated to 60°C, then isopropanol and fumed silica are added, and then sodium lignosulfonate LS and carboxymethyl cellulose ether CMC are added and stirred to be uniformly dispersed, and finally a pH adjuster is added to obtain a defoaming agent emulsion with a pH of 7, and the viscosity of the defoaming agent emulsion at room temperature is 200 mPa·s. The weight parts of each raw material are shown in Table 1 below.

[0042] Examples 2-7

[0043] Examples 2-7 provide an organosilicon antifoam emulsion prepared substantially as in Example 1, except that the type and amount of some of the ingredients are varied as shown in Tables 1-2 below. Comparative Example 1

[0044] Substantially as in Example 1, except that sodium lignosulfonate LS and carboxymethyl cellulose ether CMC are not added. Comparative Example 2

[0045] Substantially as in Example 1, except that sodium lignosulfonate LS is not added, and the amount of carboxymethyl cellulose ether CMC is adjusted to 2.3 parts. Comparative Example 3

[0046] Substantially as in Example 1, except that carboxymethyl cellulose ether CMC is not added, and the amount of sodium lignosulfonate LS is adjusted to 2.3 parts. Comparative Example 4

[0047] Substantially as in Example 1, except that sodium lignosulfonate LS is replaced by alkali lignin AL, and the amount of alkali lignin AL remains unchanged. Comparative Example 5

[0048] Substantially as in Example 1, except that sodium lignosulfonate LS is replaced by oxidized lignin OL, and the amount of oxidized lignin OL remains unchanged. Comparative Example 6

[0049] Substantially as in Example 1, except that carboxymethyl cellulose ether CMC is replaced by hydroxyethyl cellulose ether HEC, and the amount of hydroxyethyl cellulose ether HEC remains unchanged. Comparative Example 7

[0050] Substantially as in Example 1, except that carboxymethyl cellulose ether CMC is replaced by hydroxypropyl methyl cellulose HPMC, and the amount of hydroxypropyl methyl cellulose HPMC remains unchanged. Comparative Example 8

[0051] Substantially as in Example 1, except that the amount of sodium lignosulfonate LS is adjusted to 32.5 parts. Comparative Example 9

[0052] Substantially as in Example 1, except that the amount of carboxymethyl cellulose ether CMC is adjusted to 20 parts. Comparative Example 10

[0053] Substantially as in Example 1, except that the amount of pH adjuster is adjusted to control the pH of the final antifoam emulsion to 2.5. Comparative Example 11

[0054] The same as example 1, the only difference is that triethanolamine pH regulator is used to adjust the pH, and the pH of the final defoamer emulsion is controlled at 10. Comparative example 12

[0055] The same as example 1, the only difference is that sodium lignosulfonate LS is replaced by polyvinyl alcohol PVA, and the amount is kept unchanged. Comparative example 13

[0056] The same as example 1, the only difference is that sodium lignosulfonate LS is replaced by sodium polyacrylate, and the amount is kept unchanged.

[0057]

[0058]

[0059] The viscosity of the defoamer emulsion prepared in each example and comparative example is tested at room temperature, and an NDJ-8S rotary viscosity tester is used for testing. The specific steps are as follows: at room temperature, 400 mL of the prepared emulsion is taken, a No. 1 rotor is used, the rotor is kept at an angle and immersed in the sample to be tested until the rotor groove mark is flush with the liquid surface of the sample to be tested, and the rotation speed is set to 12 r / min. Each sample is measured three times and the average value is taken.

[0060] The stability of the defoamer emulsion after storage at high temperature (54±2℃) for 14 days, and the defoaming performance after storage at high temperature for 14 days are also tested. The test method is as follows: according to the requirements of GB / T 28137-2011, the foaming property of the glufosinate solution in the initial state (the solution just prepared at room temperature and not stored is tested) is tested. The specific operation steps are as follows: 180 mL of hard water (the preparation method of hard water is referred to GB / T 28137-2011) is added to a 250 mL graduated cylinder, 1 g of prepared glufosinate solution is weighed into the hard water, and finally the liquid surface is leveled to 9 cm±1 cm from the bottom of the graduated cylinder, and the plug is covered. Take the graduated cylinder as the center, upside down 180° for 30 times (2s each time). Place vertically on the test table, stand for 1 min, observe the foam volume, and repeat the same steps three times, and finally take the average as the permanent foaming determination result of the sample. When the graduated cylinder is upside down, pay attention to smooth and uniform operation, and avoid "jumping" of the liquid inside the graduated cylinder caused by violent shaking. If the foam height exceeds 60 mL, it is unqualified.

[0061] Precipitation means that, by visual observation, solid silicone is precipitated from the prepared glufosinate solution, which is no longer a homogeneous solution. Among them, the average value of three measurement data of each experiment of the initial foam height and the defoaming property after high-temperature storage is taken. The results are shown in Table 3.

[0062]

[0063] As can be seen from Table 3, by using sodium lignosulfonate LS and carboxymethyl cellulose ether CMC in the silicone defoamer emulsion at the same time and controlling the mass ratio of the two within a specific range, the two can produce a synergistic effect, so that the defoamer emulsion can exist stably at high temperature, the silicone does not precipitate, and after long-term storage at high temperature, the defoaming performance of the defoamer emulsion does not decrease significantly and can still effectively defoam. The mechanism is as described above.

[0064] In Examples 1-7, sodium lignosulfonate and carboxymethyl cellulose ether with a mass ratio of 0.4-68:1 are added to the emulsion, and the final emulsion has a suitable viscosity, excellent defoaming performance at room temperature, and no silicone precipitates after long-term storage at high temperature, and the defoaming performance is still good.

[0065] In Comparative Examples 1-3, no LS and CMC are added, or only one of them is added, and as can be seen from Table 3, although the defoamer emulsion has excellent defoaming performance at room temperature, the silicone component precipitates visibly after long-term storage at high temperature, and the defoaming performance is unqualified, which cannot achieve good defoaming. The reason is that the above-mentioned effect or the above-mentioned synergistic effect cannot be achieved, and the silicone molecules are thermally degraded at high temperature, and the emulsion is also prone to demulsification at high temperature, resulting in precipitation after long-term storage at high temperature and a sharp decrease in defoaming performance.

[0066] In Comparative Example 4, sodium lignosulfonate LS is replaced by alkali lignin AL, and as can be seen from Table 3, although the defoamer has good defoaming performance at room temperature and the defoaming performance is also qualified after long-term storage at high temperature, the silicone molecules precipitate after long-term storage at high temperature. The reason is that although alkali lignin AL has a large molecular weight and good thermal stability, it has poor water solubility and cannot be well dispersed in the aqueous system, resulting in a risk of emulsion demulsification after long-term storage at high temperature, which leads to precipitation of silicone molecules.

[0067] In Comparative Example 5, sodium lignosulfonate LS is replaced by oxidized lignin OL, which is usually prepared by sodium hypochlorite bleaching process. The preparation process requires acid washing, bleaching, and acid precipitation. As can be seen from Table 3, although the defoamer has good defoaming performance at room temperature and the defoaming performance is also qualified (but poor) after long-term storage at high temperature, the silicone molecules precipitate after long-term storage at high temperature. The reason is that in the preparation process of oxidized lignin OL, the depolymerization of the chemical structure of lignin is relatively serious, resulting in a low molecular weight of OL, and the polar functional groups on OL are easily oxidized in the preparation process, and the oxidation degree is high, resulting in a lower hydrophilicity of OL than that of sodium lignosulfonate LS.

[0068] In Comparative Examples 6 and 7, carboxymethyl cellulose ether CMC is replaced by hydroxyethyl cellulose ether HEC and hydroxypropyl methyl cellulose HPMC, respectively. Although the defoaming agent has good defoaming performance at room temperature, the defoaming performance is also qualified after long-term storage at high temperature, but the silicone molecules are precipitated after long-term storage at high temperature. The reason is that hydroxyethyl cellulose ether HEC and hydroxypropyl methyl cellulose HPMC do not have carboxyl groups, and cannot play the electrostatic adsorption effect between carboxyl groups and anionic emulsifiers, and further cannot be stabilized with anionic emulsifiers.

[0069] In Comparative Examples 8 and 9, when excess sodium lignosulfonate LS or excess carboxymethyl cellulose ether CMC is used, it can be seen from Table 3 that, although the defoaming agent has good defoaming performance at room temperature, the silicone is precipitated after long-term storage at high temperature, and the defoaming performance is unqualified at this time. The reason is that the interaction between sodium lignosulfonate LS and carboxymethyl cellulose ether CMC is too strong at this time, which may cause the two to form cross-linked or easily aggregated macromolecules. These macromolecules will occupy the space position of polydimethylsiloxane in the emulsion, causing it to easily collide with each other at high temperature, and thus causing precipitation and a sharp drop in defoaming performance.

[0070] In Comparative Examples 10 and 11, when the pH of the defoaming agent emulsion is too low or too high, i.e. too acidic or too basic, it can be seen from Table 3 that the defoaming performance of the defoaming agent emulsion is poor at room temperature, and the silicone is precipitated after long-term storage at high temperature, and the defoaming performance is unqualified at this time. The reason is that the ionization of the ionic emulsifier in the emulsion system is affected at this time, and the emulsion cannot be effectively stabilized.

[0071] In Comparative Example 12, sodium lignosulfonate LS is replaced by polyvinyl alcohol PVA, and it can be seen from Table 3 that the defoaming performance of the defoaming agent emulsion is poor at room temperature, and the silicone is precipitated after long-term storage at high temperature, and the defoaming performance is unqualified at this time. The reason is that the neutral polyvinyl alcohol cannot play the various roles of the aforementioned sodium lignosulfonate (for example, PVA cannot ionize, and does not contain a benzene ring structure, and also has no strong affinity with CMC, etc.).

[0072] In Comparative Example 13, sodium lignosulfonate LS is replaced by sodium polyacrylate, and it can be seen from Table 3 that the defoaming performance of the defoaming agent emulsion is poor at room temperature, and the silicone is precipitated after long-term storage at high temperature, and the defoaming performance is unqualified at this time. The reason is that sodium polyacrylate cannot play the various roles of the aforementioned sodium lignosulfonate (for example, sodium polyacrylate does not have multiple polar functional groups, and does not contain a benzene ring structure, and also has no strong affinity with CMC, etc.).

[0073] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

[0074] The endpoints of the ranges and any values described herein are not limited to the precise values recited as essentially any range of values can be used. For values which are expressed as ranges, any intervening values, and any individual values, between the stated ranges and individual values are contemplated as being within the scope of the current application. For example, a range from 1 to 6 should be considered to include any number from 1 to 6, for example 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2, 3, 4, 5, and 6.

Claims

1. An emulsion-type silicone antifoam agent comprising a silicone, characterized in that: The defoaming agent further comprises a heat-resistant modifier, the heat-resistant modifier comprises sodium lignosulfonate and carboxymethyl cellulose ether; the mass ratio of the sodium lignosulfonate and the carboxymethyl cellulose ether is 0.4-68:1; the pH value of the defoaming agent is 5-9.

2. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The mass ratio of the sodium lignosulfonate and the carboxymethyl cellulose ether is 1-8:

1.

3. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The mass ratio of the sodium lignosulfonate and the organic silicon is 0.04-1:

1.

4. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The organic silicon is polydimethylsiloxane.

5. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The defoaming agent further comprises an anionic emulsifier and a nonionic emulsifier.

6. The emulsion-type silicone antifoam according to claim 5, characterized in that: The anionic emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polycarboxylate and sodium polyacrylate; and / or, the nonionic emulsifier is selected from at least one of fatty alcohol polyoxyethylene ether, Tween, Span; and / or, the mass ratio of the anionic emulsifier and the nonionic emulsifier is 0.5-0.8:

1.

7. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The defoaming agent further comprises at least one of a cosolvent, a thickening agent, a pH regulator.

8. The emulsion-type silicone antifoam according to claim 7, characterized by: The cosolvent is selected from at least one of isopropyl alcohol, ethanol, ethylene glycol, n-propanol; and / or, the thickening agent is selected from at least one of fumed silica, bentonite; and / or, the pH regulator is selected from sulfuric acid, hydrochloric acid, citric acid, triethanolamine or ammonia water.

9. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The defoaming agent comprises polydimethylsiloxane, sodium lignosulfonate, carboxymethyl cellulose ether, an anionic emulsifier, a nonionic emulsifier, a cosolvent, a thickening agent, a pH regulator and water.

10. The emulsion-type silicone antifoam agent according to claim 9, characterized by: In terms of weight parts, the defoaming agent comprises 20-30 parts of polydimethylsiloxane, 0.5-30 parts of sodium lignosulfonate, 0.1-10 parts of carboxymethyl cellulose ether, 1-5 parts of an anionic emulsifier, 1-5 parts of a nonionic emulsifier, 3-10 parts of a cosolvent, 0.1-0.8 parts of a thickening agent, 55-65 parts of water, and the amount of the pH regulator is such that the pH value of the defoaming agent is 5-9.

11. The emulsion-type silicone antifoam agent according to claim 9, characterized by: In terms of weight parts, the defoaming agent comprises 22-26 parts of polydimethylsiloxane, 1-20 parts of sodium lignosulfonate, 0.2-5 parts of carboxymethyl cellulose ether, 1-3 parts of an anionic emulsifier, 2-4 parts of a nonionic emulsifier, 4-6 parts of a cosolvent, 0.1-0.3 parts of a thickening agent, 63-65 parts of water, and the amount of the pH regulator is such that the pH value of the defoaming agent is 5-9.

12. The emulsion-type silicone antifoam agent according to claim 1, characterized by: The pH value of the defoaming agent is 6-8; and / or, the viscosity of the defoaming agent at 20°C is 100-300 mPa·s.

13. A process for the preparation of the emulsion-type silicone antifoam agent according to any one of claims 1 to 12, characterized in that: The preparation method comprises the following steps: 1) mixing and dispersing organic silicon, an anionic emulsifier, a nonionic emulsifier and water to obtain a mixed solution; 2) heating the mixed solution, then adding a cosolvent, a thickening agent, sodium lignosulfonate and carboxymethyl cellulose ether, stirring and dispersing, and then adding a pH regulator to obtain the emulsion-type organic silicon defoaming agent.

14. Use of the emulsion-type organic silicon defoaming agent of any one of claims 1-12 for defoaming glufosinate-ammonium aqueous solution.

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