High-stability organic silicon defoaming agent and preparation method thereof

Abstract

The invention relates to the technical field of defoaming agents, and particularly discloses a high-stability organic silicon defoaming agent and a preparation method thereof. Under the preferable proportioning condition, the surface active component blocks direct contact between oil drops and water, the large steric hindrance of the silicon polyether limits movement of various surface active components on the surfaces of the oil drops, the emulsifying auxiliary agent and the floating oil improver are associated with hydrophilic groups, exposed out of the oil drops, of the surface active component through hydrogen bonds, and the surface active component can be separated from the surface active component. The organic silicon defoaming agent provided by the invention can be used for blocking the combination of oil drops, so that the organic silicon defoaming agent is not easy to demulsify even under a high-temperature storage condition, can maintain a stable state for a long time, is not easy to generate the phenomena of particle size enlargement, silicone grease precipitation and the like, and has good high-temperature-resistant stability.

Description

Technical Field

[0001] The present application relates to the technical field of defoaming agents, and more specifically, to a high-stability organosilicon defoaming agent and a preparation method thereof. Background Art

[0002] Organic silicon defoamer is a chemical additive widely used in industrial production, mainly used to control and eliminate the foam generated in the production process. When organic silicon defoamer is added to the foam system, the defoaming components will quickly diffuse to the gas-liquid interface of the foam, destroying the stability of the foam and causing the foam to burst. Due to this characteristic of organic silicon defoamer, it is widely used in coatings, inks, papermaking, textiles, fermentation, food processing, pharmaceutical manufacturing and other industries.

[0003] The use of silicone defoamers began in the late 1930s. Silicone can be used as a defoamer because it has the following characteristics: (1) Low surface tension: From the defoaming mechanism, it can be seen that the surface tension of the defoamer must be lower than the surface tension of the foaming liquid. Dimethyl silicone oil has the characteristic of low surface tension, so the application range of dimethyl silicone oil defoamers is very wide. (2) Low solubility in water and general oily solvents: Polysiloxane has a special molecular structure, and its main chain is a silicon-oxygen chain, which is not compatible with water and has low affinity with general oily solvents. Therefore, a small amount of dimethyl silicone oil can have high activity. (3) The chemical inertness and physiological inertness of dimethyl silicone oil are also an important reason why it is widely used as a defoamer.

[0004] With respect to the above-mentioned related technologies, the inventors believe that although the organosilicon defoamers currently on the market have certain defoaming capabilities, their high-temperature stability is poor when the content of active ingredients is high. When stored for a long time in a high-temperature environment, they are prone to particle size enlargement and silicone grease precipitation, which affects subsequent use. Summary of the invention

[0005] In the related art, the organosilicon defoamer has poor high temperature stability when the active ingredient content is high, and is prone to particle size enlargement and silicone grease precipitation when stored in a high temperature environment for a long time. In order to improve this defect, the present application provides a high-stability organosilicon defoamer and a preparation method thereof.

[0006] In the first aspect, the present application provides a high-stability organosilicon defoamer, which adopts the following technical solution: A high-stability organosilicon defoamer comprises the following components in weight percentage: 20-30% silicone grease, 20-30% composite emulsifier, 3-5% stabilizer, 2-4% thickener, 3-5% bleaching oil improving agent, and the balance is supplemented to 100% by water; the composite emulsifier comprises the following components in weight parts: 0.01-0.5 parts of anionic surfactant, 3-5 parts of nonionic surfactant, 10-20 parts of silicone polyether, and 1-5 parts of emulsifying aid, wherein the emulsifying aid is fatty alcohol and / or polyol, and the bleaching oil improving agent is polyether.

[0007] By adopting the above technical scheme, the present application uses a composite emulsifier containing anionic surfactants, nonionic surfactants, silicone polyethers and emulsifying aids to prepare a silicone defoamer. In the silicone defoamer product of the present application, silicone grease exists in the form of oil droplets, and the hydrophobic ends of the anionic surfactants, nonionic surfactants and silicone polyethers in the composite emulsifier are inserted into the oil droplets, and the hydrophilic ends extend out of the oil droplets, forming a transition layer between the oil droplets and water. Under the preferred ratio conditions of the present application, the anionic surfactants, nonionic surfactants and silicone polyethers fully reduce the surface tension of the oil droplets through synergistic effects, and effectively block the direct contact between the oil droplets and water. At the same time, the emulsifying aid and the floating oil improver can form hydrogen bonds with the hydrophilic groups of these surfactant components exposed outside the oil droplets, thereby limiting the mutual contact between the oil droplets and hindering the merging of the oil droplets. The hydrogen bond itself has good heat resistance, and the large steric hindrance of the silicone polyether limits the movement of various surfactant components on the surface of the oil droplet. Therefore, the silicone defoamer of the present application is not easy to demulsify even under high-temperature storage conditions, can maintain a stable state for a long time, and is not prone to particle size enlargement, silicone grease precipitation, etc., which fully overcomes the defects of traditional silicone defoamers.

[0008] Preferably, the nonionic surfactant includes at least one of alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ether, fatty alcohol polyoxyethylene ether, Span, Tween, and castor oil polyoxyethylene ether.

[0009] By adopting the above technical scheme, the present application optimizes the type of non-ionic surfactant. The above-mentioned non-ionic surfactants all contain a polyoxyethylene ether structure. The polyoxyethylene ether structure has good hydrophilicity and can fully form hydrogen bonds with the emulsifier on the outside of the oil droplets, thereby improving the stability of the silicone defoamer under high temperature conditions.

[0010] Preferably, the alkylphenol polyoxyethylene ether includes at least one of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, dodecylphenol polyoxyethylene ether and dinonylphenol polyoxyethylene ether.

[0011] By adopting the above technical scheme, the present application further optimizes the type of alkylphenol polyoxyethylene ether, among which dodecylphenol polyoxyethylene ether has a longer alkyl group, and dinonylphenol polyoxyethylene ether has two alkyl side chains. These two types of alkylphenol polyoxyethylene ethers can effectively increase the density of hydrophobic groups on the inner side of oil droplets, help reduce the high-temperature demulsification of the silicone defoamer, make it less likely to have particle size enlargement, silicone grease precipitation, etc., and improve the stability of the silicone defoamer.

[0012] Preferably, the fatty acid polyoxyethylene ether includes at least one of lauric acid polyoxyethylene ether, oleic acid polyoxyethylene ether, palmitic acid polyoxyethylene ether and stearic acid polyoxyethylene ether.

[0013] By adopting the above technical scheme, the present application preferably selects the type of fatty acid polyoxyethylene ether. The above fatty acid polyoxyethylene ethers can make the silicone defoamer have good high temperature stability by combining with anionic surfactants and emulsifying aids.

[0014] Preferably, the silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a hydrosilylation reaction, and the unsaturated monomer is any two of allyl alcohol polyether, acetylene glycol polyether, liquid olefin, and vinyl silicone oil.

[0015] By adopting the above technical scheme, the present application preferably selects the composition of silicone polyether, wherein hydrogenated silicone oil is the matrix of silicone polyether, which mainly plays a role similar to that of silicone paste. Allyl alcohol polyether, acetylene glycol polyether, liquid olefin, and vinyl silicone oil can all undergo silylation reaction with hydrogenated silicone oil through unsaturated bonds to obtain silicone polyether. Allyl alcohol polyether can adjust the hydrophilic-lipophilic balance value; the main function of acetylene glycol polyether and liquid olefin is to improve the spreadability of the defoamer, which helps to achieve rapid defoaming; vinyl silicone oil can also play a role similar to that of silicone paste while adjusting the viscosity of silicone polyether. By selecting any two of allyl alcohol polyether, acetylene glycol polyether, liquid olefin, and vinyl silicone oil to react with hydrogenated silicone oil, a silicone polyether with relatively ideal performance and helpful to improve the high temperature stability of silicone defoamer can be obtained.

[0016] Preferably, the hydrogen content of the hydrogen-containing silicone oil is 0.1-0.36%.

[0017] By adopting the above technical solution, the present application preferably selects the hydrogen content range of the hydrogen-containing silicone oil, within which a silicone polyether with good compatibility with silicone paste can be obtained through a hydrosilylation reaction.

[0018] Preferably, the structural formula of the allyl alcohol polyether is CH2=CHCH2O(C3H6O) m (C2H4O) n H, where m ranges from 0 to 14 and n ranges from 0 to 20.

[0019] By adopting the above technical solution, the present application defines the parameter range of the structural unit of allyl alcohol polyether, within which a silicone polyether with a relatively ideal hydrophilic-lipophilic balance value can be obtained through a hydrosilylation reaction.

[0020] Preferably, the bleaching oil improving agent is polyethylene glycol, polypropylene glycol or polyethylene glycol polypropylene glycol polyoxyethylene ether.

[0021] By adopting the above technical solution, the present application preferably selects the type of float oil improver. Among the above-mentioned float oil improvers, polypropylene glycol can more effectively hinder the merging of oil droplets, which helps to enhance the high temperature stability of the silicone defoamer.

[0022] Preferably, the stabilizer is modified halloysite nanotubes, and the modified halloysite nanotubes are prepared according to the following method: (1) drying the halloysite nanotubes and adding them to an aqueous solution containing a silane coupling agent, performing ultrasonic dispersion and then heating, and then filtering and washing to obtain silanized halloysite nanotubes; the silane coupling agent includes KH570 and KH550; (2) acrylamide, silanized halloysite nanotubes, an inhibitor, and sodium dodecylbenzene sulfonate are added to deionized water to obtain a mixed solution, the mixed solution is ultrasonically dispersed, and then an initiator is added to the mixed solution. After heating and reaction, the mixed solution is filtered, the filter residue is crushed, and modified halloysite nanotubes are obtained after Soxhlet extraction and vacuum drying.

[0023] By adopting the above technical solution, the present application first introduces amino and vinyl groups on the surface of halloysite nanotubes using a silane coupling agent, and then copolymerizes vinyl groups with acrylamide in an aqueous solution to obtain modified halloysite nanotubes with long chains of polyacrylamide on the surface. The modified halloysite nanotubes can form hydrogen bonds with the hydrophilic groups of the surfactant components exposed outside the oil droplets, the emulsifying aid, and the oil bleaching improver through the amino groups in the long chains of polyacrylamide, which helps to maintain the suspension of the oil droplets and improves the high temperature stability of the silicone defoamer.

[0024] In a second aspect, the present application provides a method for preparing a high-stability organosilicon defoamer, using the following technical solution.

[0025] A method for preparing a high-stability organosilicon defoamer comprises the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 100-1000 rpm for 10-60 min to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding a portion of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0026] By adopting the above technical solution, the present application first premixes the silicone grease and the composite emulsifier, and obtains a pre-emulsified liquid after emulsification by adding water. By adding a thickener to the pre-emulsified liquid in two steps, and adding a stabilizer and a bleaching oil improver at the same time as the second addition of the thickener, a highly stable organosilicon defoamer can be obtained.

[0027] In summary, this application has the following beneficial effects: 1. Under the preferred ratio conditions of the present application, the surfactant components block the direct contact between the oil droplets and water, the larger steric hindrance of the silicone polyether limits the movement of various surfactant components on the surface of the oil droplets, and the emulsifying aid and the floating oil improver form associations with the hydrophilic groups of the surfactant components exposed outside the oil droplets through hydrogen bonds, which hinders the merging of the oil droplets, making it difficult for the organosilicon defoamer to break even under high-temperature storage conditions, and can maintain a stable state for a long time, and is not prone to the phenomenon of particle size enlargement and silicone grease precipitation, and has good high-temperature stability.

[0028] 2. The present application prepares modified halloysite nanotubes with long chains of polyacrylamide on the surface. The modified halloysite nanotubes can form hydrogen bonds with the hydrophilic groups of the surfactant components exposed outside the oil droplets, emulsifiers and bleaching oil improvers through the amino groups in the long chains of polyacrylamide, which helps to maintain the suspension of the oil droplets and improve the high temperature stability of the silicone defoamer. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0030] Preparation example of modified halloysite nanotubes The following is an explanation using Preparation Example 1.

[0031] Preparation Example 1 In this preparation example, the modified halloysite nanotubes were prepared according to the following method: (1) After drying halloysite nanotubes (CAS: 60676-86-0) at 50°C for 5 hours, the mixture was added to an aqueous solution containing a silane coupling agent, and then ultrasonically dispersed for 1 hour and heated at 110°C for 8 hours. The mixture was then filtered and the filtrate was washed with toluene to obtain silanized halloysite nanotubes; the silanized halloysite nanotubes in toluene were vacuum filtered and Soxhlet extracted, then dried at 50°C for 10 hours for later use; the silane coupling agents were KH570 and KH550, wherein the amount of KH570 was 8% of the weight of the halloysite nanotubes. The amount of KH550 was 2% of the weight of the halloysite nanotubes; (2) acrylamide, silanized halloysite nanotubes, an inhibitor, sodium dodecylbenzene sulfonate, and deionized water are mixed in a weight ratio of 5:1:1:1:20 to obtain a mixed solution, the mixed solution is ultrasonically dispersed for 1 hour, and then an initiator is added to the mixed solution, and the mixed solution is heated at 70° C. for reaction for 4 hours and then filtered, the filter residue is crushed, and modified halloysite nanotubes are obtained after Soxhlet extraction and vacuum drying; in this step, the inhibitor is copper sulfate pentahydrate, the initiator is ammonium persulfate, and the amount of the initiator is 0.5wt% of the total weight of the polymerization system. Example

[0032] Examples 1-5 The following description is given by taking Example 1 as an example.

[0033] Example 1 In this embodiment, the viscosity of the silicone grease is 100000 cPs, the emulsifying agent is ethanol, and the bleaching oil improving agent is polyethylene glycol (PEG2000); the anionic surfactant is a mixture of sodium lauryl polyoxyethylene ether sulfate (CAS#: 68585-34-2), 3-acylglycerol-1,2-disulfate and sodium dodecyl sulfate in a weight ratio of 1:1:4; the nonionic surfactant is a mixture of castor oil polyoxyethylene ether and alkylphenol polyoxyethylene ether in a weight ratio of 1:1, and the alkylphenol polyoxyethylene ether is a mixture of nonylphenol polyoxyethylene ether (NP-10) and octylphenol polyoxyethylene ether (OP-4) in a weight ratio of 1:5; the stabilizer is the modified halloysite nanotubes of Preparation Example 1, and the thickener is xanthan gum (CAS: 11138-66-2).

[0034] In this embodiment, the silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a silylation reaction, the hydrogenated silicone oil has a hydrogen content of 0.1%, the unsaturated monomers are vinyl silicone oil and allyl alcohol polyether, the vinyl content of the vinyl silicone oil is 0.23, the viscosity is 2000 cPs, and the structural formula of allyl alcohol polyether can be expressed as CH2=CH-CH2O(C3H6O)3(C2H4O)5H. The weight ratio of hydrogenated silicone oil, vinyl silicone oil, allyl alcohol polyether and platinum catalyst is 0.56:0.14:0.3:7ppm, and the preparation process of the silicone polyether is: adding materials, adding platinum catalyst when the temperature rises to 60°C, continuing to heat until the system becomes clear, then keeping the temperature for 30 minutes, and cooling to obtain the silicone polyether.

[0035] The present embodiment provides a high-stability organosilicon defoamer, comprising the following components in weight percentage: 30% silicone grease, 20% composite emulsifier, 3% stabilizer, 2% thickener, 3% bleaching oil improver, and the balance is supplemented by water to 100%; the composite emulsifier comprises the following components: 0.01kg anionic surfactant, 3kg nonionic surfactant, 10kg silicone polyether, and 1kg emulsifying aid.

[0036] This embodiment provides a method for preparing a high-stability organosilicon defoamer, comprising the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 100 rpm for 60 min to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding half of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0037] Example 2 In this embodiment, the viscosity of the silicone grease is 100000 cPs, the emulsifying agent is ethylene glycol, the bleaching oil improving agent is polyethylene glycol polypropylene glycol polyoxyethylene ether (EO / PO=1, average molecular weight is 3500); the anionic surfactant is a mixture of sodium potassium laurate sulfonate, sodium ethylhexyl succinate sulfonate and sodium N,N-oleoylmethyl taurate in a weight ratio of 1:1:1; the nonionic surfactant is a mixture of fatty acid polyoxyethylene ether and alkylphenol polyoxyethylene ether in a weight ratio of 1:1. The fatty acid polyoxyethylene ether is mixed with lauric acid polyoxyethylene ether (LAE-4) and oleic acid polyoxyethylene ether (OEO-10) in a weight ratio of 3:5, and the alkylphenol polyoxyethylene ether is mixed with dodecylphenol polyoxyethylene ether (OP-10) and dinonylphenol polyoxyethylene ether (DNPEO) in a weight ratio of 1:5; the stabilizer is the modified halloysite nanotubes of Preparation Example 1, and the thickener is xanthan gum (CAS: 11138-66-2).

[0038] In this embodiment, the silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a silylation reaction, the hydrogenated silicone oil has a hydrogen content of 0.15%, the unsaturated monomer is a liquid olefin and an allyl alcohol polyether, the liquid olefin is dodecene, and the structural formula of the allyl alcohol polyether can be expressed as CH2=CH-CH2O(C2H4O) 20 H. The weight ratio of hydrogenated silicone oil, liquid olefin, allyl alcohol polyether and platinum catalyst is 0.39:0.05:0.56:7ppm, and the preparation process of silicone polyether is as follows: adding materials, adding platinum catalyst when the temperature reaches 60°C, continuing to heat until the system becomes clear, then keeping the temperature for 30 minutes, and cooling to obtain silicone polyether.

[0039] The present embodiment provides a high-stability organosilicon defoamer, comprising the following components in weight percentage: 28% silicone grease, 22% composite emulsifier, 3.5% stabilizer, 2.5% thickener, 3.5% bleaching oil improver, and the balance is supplemented to 100% by water; the composite emulsifier comprises the following components: 0.1kg anionic surfactant, 3.5kg nonionic surfactant, 12kg silicone polyether, and 2kg emulsifying aid.

[0040] This embodiment provides a method for preparing a high-stability organosilicon defoamer, comprising the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 200 rpm for 50 min to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding half of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0041] Example 3 In this embodiment, the viscosity of the silicone grease is 100000 cPs, the emulsifying agent is propylene glycol, and the bleaching oil improver is PPG1000; the anionic surfactant is formed by mixing sodium butylnaphthalene sulfonate, sodium dodecylbenzene sulfonate and sodium dodecyl sulfonate in a weight ratio of 1:1:2; the nonionic surfactant is formed by mixing fatty acid polyoxyethylene ether and fatty alcohol polyoxyethylene ether in a weight ratio of 2:1, the fatty acid polyoxyethylene ether is formed by mixing palmitic acid polyoxyethylene ether and stearic acid polyoxyethylene ether (SG-100) in a weight ratio of 3:5, and the fatty alcohol polyoxyethylene ether is lauryl alcohol polyoxyethylene ether; the stabilizer is the modified halloysite nanotubes of Preparation Example 1, and the thickener is xanthan gum (CAS: 11138-66-2).

[0042] In this embodiment, the silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a silylation reaction, the hydrogenated silicone oil has a hydrogen content of 0.2%, the unsaturated monomer is an acetylene glycol polyether and an allyl alcohol polyether, the acetylene glycol polyether is formed by grafting hydroxyl groups at both ends of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and EO structural units, and the grafting number of EO structural units in the acetylene glycol polyether is 14.3 on average; the structural formula of the allyl alcohol polyether can be expressed as CH2=CH-CH2O(C3H6O) 14 H. The weight ratio of hydrogenated silicone oil, acetylene glycol polyether, allyl alcohol polyether and platinum catalyst is 0.47:0.15:0.38:15ppm, and the preparation process of silicone polyether is as follows: adding materials, adding platinum catalyst when the temperature reaches 60°C, continuing to heat until the system becomes clear, then keeping the temperature for 30 minutes, and cooling to obtain silicone polyether.

[0043] The present embodiment provides a high-stability organosilicon defoamer, comprising the following components in weight percentage: 25% silicone grease, 25% composite emulsifier, 4% stabilizer, 3% thickener, 4% bleaching oil improver, and the balance is supplemented by water to 100%; the composite emulsifier comprises the following components: 0.3kg anionic surfactant, 4kg nonionic surfactant, 15kg silicone polyether, and 3kg emulsifying aid.

[0044] This embodiment provides a method for preparing a high-stability organosilicon defoamer, comprising the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 400 rpm for 40 minutes to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding half of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0045] Example 4 In this embodiment, the viscosity of the silicone grease is 100000 cPs, the emulsifying agent is n-butanol, and the bleaching oil improver is PPG2000; the anionic surfactant is formed by mixing sodium hexadecyl sulfonate, sodium hexadecylbenzene sulfonate and sodium dodecyl diphenyl ether disulfonate in a weight ratio of 1:2:3; the nonionic surfactant is formed by mixing Span 60, Span 80, Tween 60 and Tween 80 in a weight ratio of 1:1:2:2; the stabilizer is the modified halloysite nanotubes of Preparation Example 1, and the thickener is xanthan gum (CAS: 11138-66-2).

[0046] In this embodiment, the silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a silylation reaction, the hydrogenated silicone oil has a hydrogen content of 0.28%, the unsaturated monomers are acetylene glycol polyether and allyl alcohol polyether, the acetylene glycol polyether is formed by grafting hydroxyl groups at both ends of 1,4-butanediol and EO structural units, and the grafting number of EO structural units in the acetylene glycol polyether is 12.6 on average; the structural formula of allyl alcohol polyether can be expressed as CH2=CH-CH2O(C3H6O) 14 H. The weight ratio of hydrogen-containing silicone oil, acetylene glycol polyether, allyl alcohol polyether and platinum catalyst is 0.39:0.05:0.56:17ppm, and the preparation process of silicone polyether is as follows: adding materials, adding platinum catalyst when the temperature reaches 60°C, continuing to heat until the system becomes clear, then keeping the temperature for 30 minutes, and cooling to obtain silicone polyether.

[0047] The present embodiment provides a high-stability organosilicon defoamer, comprising the following components in weight percentage: 22% silicone grease, 28% composite emulsifier, 4.5% stabilizer, 3.5% thickener, 4.5% bleaching oil improver, and the balance is supplemented to 100% by water; the composite emulsifier comprises the following components: 0.4kg anionic surfactant, 4.5kg nonionic surfactant, 18kg silicone polyether, and 4kg emulsifying aid.

[0048] This embodiment provides a method for preparing a high-stability organosilicon defoamer, comprising the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 500 rpm for 30 min to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding half of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0049] Example 5 In this embodiment, the viscosity of the silicone grease is 100000 cPs, the emulsifying agent is glycerol, and the bleaching oil improver is PPG4000; the anionic surfactant is formed by mixing sodium hexadecyl sulfonate, sodium hexadecylbenzene sulfonate and sodium dodecyl diphenyl ether disulfonate in a weight ratio of 1:1:3; the nonionic surfactant is formed by mixing Span 65, Span 85, Tween 65 and Tween 85 in a weight ratio of 1:1:3:3; the stabilizer is the modified halloysite nanotubes of Preparation Example 1, and the thickener is xanthan gum (CAS: 11138-66-2).

[0050] In this embodiment, the silicon polyether is obtained by hydrogenated silicone oil and unsaturated monomers through a silylation reaction. The hydrogen content of the hydrogenated silicone oil is 0.36%. The unsaturated monomers are acetylene glycol polyether and allyl alcohol polyether. The acetylene glycol polyether is formed by grafting hydroxyl groups at both ends of 1,4-butanediol and EO structural units. In the acetylene glycol polyether, the number of grafted EO structural units is 12.6 on average. The structural formula of allyl alcohol polyether can be expressed as CH2=CH-CH2O(C3H6O)2(C2H4O)5H. The weight ratio of hydrogenated silicone oil, acetylene glycol polyether, allyl alcohol polyether and platinum catalyst is 0.35:0.1:0.56:20ppm. The preparation process of silicon polyether is as follows: feed, add platinum catalyst when the temperature rises to 60°C, continue to heat until the system becomes clear, then keep the temperature for 30 minutes, and cool down to obtain silicon polyether.

[0051] The present embodiment provides a high-stability organosilicon defoamer, comprising the following components in weight percentage: 20% silicone grease, 30% composite emulsifier, 5% stabilizer, 4% thickener, 5% bleaching oil improver, and the balance is supplemented by water to 100%; the composite emulsifier comprises the following components: 0.5kg anionic surfactant, 5kg nonionic surfactant, 20kg silicone polyether, and 5kg emulsifying aid.

[0052] This embodiment provides a method for preparing a high-stability organosilicon defoamer, comprising the following steps: (1) mixing silicone grease and composite emulsifier, stirring and dispersing at 1000 rpm for 10 min to obtain a premix; (2) adding water to the premix for emulsification, continuously sampling to test the particle size during the water addition process, and observing the phase transition temperature. When the particle size D90 is detected to be ≤20 μm, the water addition is stopped to obtain a pre-emulsified liquid; (3) adding the remaining water to the pre-emulsion and stirring evenly, and then adding half of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable organosilicon defoamer.

[0053] Example 6 The difference between this embodiment and embodiment 2 is that dodecylphenol polyoxyethylene ether (OP-10) is replaced by octylphenol polyoxyethylene ether (OP-4), and dinonylphenol polyoxyethylene ether (DNPEO) is replaced by nonylphenol polyoxyethylene ether (NP-10).

[0054] Example 7 The difference between this embodiment and embodiment 1 is that the modified halloysite nanotubes are replaced with halloysite nanotubes (CAS: 60676-86-0) of the same weight.

[0055] Comparative Example Comparative Example 1 The difference between this comparative example and Example 3 is that the silicone polyether in the composite emulsifier component is completely replaced by a nonionic surfactant.

[0056] Comparative Example 2 The difference between this comparative example and Example 3 is that the components of the composite emulsifier do not include an emulsifying aid.

[0057] Comparative Example 3 The difference between this comparative example and Example 3 is that the components of the composite emulsifier do not include anionic surfactants.

[0058] Comparative Example 4 The difference between this comparative example and Example 3 is that the components of the composite emulsifier do not include a nonionic surfactant.

[0059] Comparative Example 5 The difference between this comparative example and Example 3 is that the defoaming agent does not include a stabilizer.

[0060] Comparative Example 6 The difference between this comparative example and Example 3 is that the defoaming agent does not include a bleaching oil improving agent.

[0061] Performance testing methods 1. Oven aging particle size test The D90 particle size in the silicone defoamer was detected using an LS-POP (9) laser particle size analyzer. The silicone defoamer was added to a sealed container and allowed to stand in an oven at 50°C for 7 days. The D90 particle size in the silicone defoamer was then detected again. The ratio of the D90 particle size before and after standing was calculated and recorded as the particle size ratio. The results are shown in Table 1.

[0062] 2. Shear precipitation test of oven aging samples The organosilicon defoamer was diluted to a solid content of 30% (solid content is the sum of the weight percentages of all components except water), and then the dilution was placed at 50°C for 45 hours, sheared at a rate of 300 r / min for 1 hour, and then filtered. The precipitate was dried and weighed, recorded as the precipitation amount, and the precipitation amount of Comparative Example 1 was used as a benchmark to calculate the ratio between the precipitation amount of each embodiment and comparative example and the precipitation amount of Comparative Example 1, and the ratio was recorded as the relative precipitation amount. The results are shown in Table 1.

[0063] Table 1 Test results sample Particle size ratio Relative precipitation amount / % Example 1 1.43 65.7 Example 2 1.48 62.1 Example 3 1.50 64.7 Example 4 1.49 62.5 Example 5 1.54 61.6 Example 6 2.31 66.3 Example 7 2.54 73.6 Comparative Example 1 4.76 100.0 Comparative Example 2 4.13 82.3 Comparative Example 3 3.94 75.9 Comparative Example 4 4.08 78.1 Comparative Example 5 3.72 73.8 Comparative Example 6 4.31 84.5 Combining Examples 1-5 and Comparative Examples 1-6 and Table 1, it can be seen that the particle size ratio and relative precipitation amount measured in Examples 1-5 are lower than those in Comparative Examples 1-6. This is because under the preferred conditions of the present application, the surfactant components fully reduce the surface tension of the oil droplets through synergistic action, effectively blocking the direct contact between the oil droplets and water, and the larger steric hindrance of the silicone polyether limits the movement of various surfactant components on the surface of the oil droplets. The emulsifying aid and the floating oil improver form an association with the hydrophilic groups of the surfactant components exposed outside the oil droplets through hydrogen bonds, which hinders the merging of the oil droplets. Through the coordinated coordination of the various components, the organosilicon defoamer of the present application is not easy to demulsify even under high temperature storage conditions, can maintain a stable state for a long time, is not prone to particle size enlargement, silicone grease precipitation and other phenomena, and has good high temperature stability.

[0064] Combining Example 3 and Comparative Example 1 with Table 1, it can be seen that in the absence of silicone polyether in the composite emulsifier, various surfactant components on the surface of the oil droplets are easier to migrate under high temperature conditions, resulting in an increase in the degree of demulsification of the defoaming agent. Therefore, the particle size ratio and relative precipitation amount measured in Comparative Example 1 are significantly higher than those in Example 3.

[0065] Combining Example 3 and Comparative Example 2 with Table 1, it can be seen that when the composite emulsifier lacks an emulsifying aid, the hydrophilic groups of the surfactant components exposed outside the oil droplets fail to fully form hydrogen bonds, resulting in an increase in the degree of demulsification of the defoaming agent. Therefore, the particle size ratio and relative precipitation amount measured in Comparative Example 2 are significantly higher than those in Example 3.

[0066] It can be seen from Example 3 and Comparative Examples 3-4 and Table 1 that when any one of the anionic surfactant and the nonionic surfactant is missing in the composite emulsifier, the surfactant component cannot fully reduce the surface tension of the oil droplets through synergistic action, resulting in an increase in the degree of demulsification of the defoaming agent. Therefore, the particle size ratio and relative precipitation amount measured in Comparative Examples 3-4 are significantly higher than those in Example 3.

[0067] Combining Example 3 and Comparative Examples 5-6 with Table 1, it can be seen that when any one of the stabilizer and the floating oil improver is missing in the composite emulsifier, the hydrophilic groups of the surfactant components exposed outside the oil droplets fail to fully form hydrogen bonds, resulting in an increase in the degree of demulsification of the defoaming agent. Therefore, the particle size ratio and relative precipitation amount measured in Comparative Examples 5-6 are significantly higher than those in Example 3.

[0068] It can be seen from Example 2 and Example 6 and Table 1 that when dodecylphenol polyoxyethylene ether and dinonylphenol polyoxyethylene ether are replaced with nonylphenol polyoxyethylene ether and octylphenol polyoxyethylene ether, the particle size ratio and the relative precipitation amount are slightly increased, indicating that dodecylphenol polyoxyethylene ether and dinonylphenol polyoxyethylene ether are more helpful to improve the high temperature stability of the defoamer.

[0069] It can be seen from Example 1 and Example 7 and Table 1 that when there is no polyacrylamide segment on the surface of the halloysite nanotubes, the hydrophilic groups of the surfactant components exposed outside the oil droplets fail to fully form hydrogen bonds, resulting in an increase in the degree of demulsification of the defoaming agent. Therefore, the particle size ratio and relative precipitation amount measured in Example 7 are significantly higher than those in Example 3.

[0070] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application without any creative contribution as needed. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A high-stability organosilicon defoamer, characterized in that: The defoamer comprises the following components in weight percentage: 20-30% silicone grease, 20-30% composite emulsifier, 3-5% stabilizer, 2-4% thickener, 3-5% bleaching oil improver, and the balance is made up to 100% by water; the composite emulsifier comprises the following components in weight parts: 0.01-0.5 parts of anionic surfactant, 3-5 parts of nonionic surfactant, 10-20 parts of silicone polyether, and 1-5 parts of emulsifying aid, wherein the emulsifying aid is fatty alcohol and / or polyol, and the bleaching oil improver is polyether.

2. The high-stability organosilicon defoamer according to claim 1, characterized in that: The nonionic surfactant includes at least one of alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ether, fatty alcohol polyoxyethylene ether, Span, Tween, and castor oil polyoxyethylene ether.

3. The high-stability organosilicon defoamer according to claim 2, characterized in that: The alkylphenol polyoxyethylene ether includes at least one of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, dodecylphenol polyoxyethylene ether and dinonylphenol polyoxyethylene ether.

4. The high-stability organosilicon defoamer according to claim 2, characterized in that: The fatty acid polyoxyethylene ether includes at least one of lauric acid polyoxyethylene ether, oleic acid polyoxyethylene ether, palmitic acid polyoxyethylene ether and stearic acid polyoxyethylene ether.

5. The high-stability organosilicon defoamer according to claim 1, characterized in that: The silicone polyether is obtained by a hydrogenated silicone oil and an unsaturated monomer through a silylation reaction, and the unsaturated monomer is any two of allyl alcohol polyether, acetylene glycol polyether, liquid olefin, and vinyl silicone oil.

6. The high-stability organosilicon defoamer according to claim 5, characterized in that: The hydrogen content of the hydrogen-containing silicone oil is 0.1-0.36%.

7. The high-stability organosilicon defoamer according to claim 5, characterized in that: The structural formula of the allyl alcohol polyether is CH2=CHCH2O(C3H6O) m (C2H4O) n H, where m ranges from 0 to 14 and n ranges from 0 to 20.

8. The high-stability organosilicon defoamer according to claim 1, characterized in that: The bleached oil improving agent is polyethylene glycol, polypropylene glycol or polyethylene glycol polypropylene glycol polyoxyethylene ether.

9. The high-stability organosilicon defoamer according to claim 1, characterized in that: The stabilizer is modified halloysite nanotubes, and the modified halloysite nanotubes are prepared according to the following method: (1) drying the halloysite nanotubes and adding them to an aqueous solution containing a silane coupling agent, performing ultrasonic dispersion and then heating, and then filtering and washing to obtain silanized halloysite nanotubes; the silane coupling agent includes KH570 and KH550; (2) Add acrylamide, silanized halloysite nanotubes, an inhibitor, and sodium dodecylbenzene sulfonate into deionized water to obtain a mixed solution, perform ultrasonic dispersion on the mixed solution, then add an initiator to the mixed solution, perform vacuum filtration after heating reaction, grind the filter residue, perform Soxhlet extraction and vacuum drying to obtain modified halloysite nanotubes.

10. The method for preparing a high-stability organosilicon defoamer according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Mix the silicone grease and the composite emulsifier, and stir and disperse them at 100-1000 rpm for 10-60 minutes to obtain a premix; (2) Add water to the premix for emulsification. During the process of adding water, continuously take samples to test the particle size and observe the phase transition temperature. When the particle size D90 is detected to be ≤ 20 μm, stop adding water to obtain a pre-emulsified liquid. (3) adding the remaining water to the pre-emulsified liquid and stirring evenly, and then adding a portion of the thickener to obtain a crude emulsion; (4) Adding a stabilizer, a bleaching oil improver and the remaining thickener to the crude emulsion to obtain a highly stable silicone defoamer.