CN119034272A - Composite organic silicon defoamer and preparation method thereof - Google Patents

Abstract

The invention discloses a composite organosilicon defoamer and a preparation method thereof, belonging to the technical field of defoamer preparation, and the raw materials include: siloxane compound, dispersant, emulsifier, thickener, solid filler, filler treatment agent, catalyst and additive; the preparation method includes: S1: filler heat treatment; S2: preparation of siloxane compound; S3: dispersion phase transition; S4: secondary emulsification; S5: cooling. Solid filler and filler treatment agent and other raw materials are added to the formula to form a composite with the siloxane compound, and the prepared defoamer has good dispersibility and stability; and by generating new chemical bonds and forming double emulsions, the obtained defoamer has good defoaming effect and stability.

Description

Composite organic silicon defoamer and preparation method thereof

Technical Field

The invention belongs to the technical field of preparation of defoamers, and particularly relates to an organosilicon defoamer for eliminating and inhibiting foaming system foam in the fields of petrochemical industry, printing and dyeing industry and paint industry.

Background

Foam is a two-phase system in which a gas is dispersed as a discontinuous phase in another continuous liquid. The liquid-gas volume of the foam system is relatively small, and the foam system is formed by distributing a large volume of gas phase in a small volume of liquid, and when the liquid-gas volume of the foam system is relatively high, the foam system can be regarded as an emulsion with a solid phase as gas. The foam is thermodynamically unstable and once formed is in the dynamic process of continuous downflow, evaporation, rupture of the liquid film. Typically by mechanical mixing of a gas (often air) with a solution (often surfactant), or by releasing the gas inside the foaming liquid due to changes in temperature, pressure, etc. Particularly foams that form in the presence of surfactants, which are undesirable in most cases due to the action of the surfactant which prevents the aggregation of the bubbles, often require the addition of an antifoaming agent to destroy and inhibit them.

Defoaming is the reverse process of foam stabilization and generally includes the two meanings of "foam inhibition" and "foam breaking" in which the defoaming agent is added to the foam-containing liquid at a very low concentration to quickly control the generation of foam and destroy the existing foam. The compound suitable as the defoaming agent is easy to spread on the surface of the solution, and when the liquid spreads on the surface of the solution, a layer of solution adjacent to the surface is taken away, so that the liquid film is locally thinned and broken, and the foam is broken. In general, the faster the defoamer spreads on the solution surface, the thinner the liquid film becomes, the faster the critical thickness is reached, the faster the foam destruction and the defoaming action is enhanced. The liquid which can spread on the surface and has the defoaming effect has lower surface tension and is easy to be adsorbed on the surface of the solution, so that the partial surface tension of the solution surface is reduced (namely the surface pressure is increased) and the imbalance phenomenon occurs. Spreading then occurs locally therefrom, and at the same time brings away the next layer of liquid adjacent to the surface, causing thinning of the liquid film and hence destruction of the bubble film. Therefore, the reason for defoaming is that the defoamer molecules which are easy to spread and absorb replace the foamer molecules to form a film with poor strength, and meanwhile, part of the solution adjacent to the surface layer is carried away in the spreading process to thin the foam liquid film, so that the stability of the foam is reduced and the foam is easy to damage.

The organic silicon defoamer is used as a widely applied defoamer, has extremely low surface tension, can be rapidly unfolded on the surface of foam and destroy the foam structure, thereby playing a role in defoaming, can maintain the chemical stability at a higher temperature, is suitable for being used under various different temperature conditions, is difficult to chemically react with other substances due to extremely stable Si-O bond in the chemical structure, can be used in a system containing acid, alkali and salt, is proved to be harmless to human bodies and animals, can be safely used in the industries of food, medical treatment and the like, and can effectively destroy the generated foam under the condition of small using amount, and the foam regeneration can be obviously inhibited, so that the defoaming effect can be generated by only adding one part of the weight of a foaming medium. In conclusion, the organic silicon defoamer has wide application value in a plurality of industrial fields by virtue of low surface tension, excellent thermal stability, chemical stability and physiological inertia and strong defoaming force.

Typically, silicone defoamers are prepared in the form of emulsions in order to allow the defoamer to disperse effectively in the bubble medium. However, in the preparation of the existing silicone defoamer, since the polysiloxane is difficult to disperse and insoluble in water, its dispersion in the water system is hindered, and an emulsifier must be added. If the emulsifier is excessively added, the emulsion is stable, but the defoaming effect is poor, and if the amount of the emulsifier is excessively small, the defoaming agent emulsion is unstable and layering is easy to occur. Therefore, in the actual operation process, the stability and the defoaming efficacy of the defoaming agent prepared by the prior art are often difficult to be simultaneously achieved due to the fact that the dosage is difficult to control.

The Chinese patent with the application number of CN20161154366. X discloses an organic silicon defoamer, wherein the defoamer comprises, by weight, 10-40% of polyether modified polysiloxane, 10-25% of silicone resin, 1-5% of a dispersing agent, 40-60% of water, 5-25% of an emulsifying agent and 100% of total components. The organic silicon defoamer can provide a reasonable channel for the treatment of the high-boiling-point substances of the organic silicon byproducts, improves the stability and the dispersibility of the emulsion, ensures the storage time, greatly improves the instant defoaming capability and ensures the use temperature range of raw materials. However, this application simply selects conventional agents for compounding and does not disclose the reason for the improved stability of the emulsion and how a balance is achieved between the defoaming efficacy and stability of the defoamer.

The Chinese patent with the application number of CN202111649422.8 discloses a polyether modified organosiloxane emulsion type defoamer, which belongs to the field of organosilicon defoamers and comprises, by weight, 30-50 parts of polyether modified organosiloxane, 6-18 parts of polysiloxane, 10-20 parts of composite emulsifier, 1-4 parts of thickener, 0.1-3 parts of stabilizer, 8-14 parts of nano dispersing agent and 60-80 parts of water, wherein the nano dispersing agent is modified silica nano-sheets. The invention mainly reduces the influence of polyether modification on defoaming and foam inhibiting performance of the defoamer through the composite polysiloxane, improves the stability of emulsion through the composite emulsifier, and further improves the dispersibility and the defoaming performance through the addition of the nano dispersing agent. However, the application requires additional preparation of the nano dispersing agent to achieve a better dispersing effect, which causes complicated process.

The Chinese patent with the application number of CN201811271649.1 discloses a modified organic silicon defoamer which comprises, by weight, 20-40 parts of polysiloxane, 15-30 parts of hydrophobic silica, 5-15 parts of higher alcohols, 3-5 parts of isopropyl citrate, 2-4 parts of methyl acrylate, 2-4 parts of monoglyceride, 1-3 parts of sodium hexametaphosphate, 0.5-2 parts of sodium sec-alkyl sulfonate, 2-5 parts of surfactants, 1.5-3 parts of thickeners, 0-3 parts of bactericides and 70-85 parts of deionized water. The modified organic silicon defoamer obtained by the invention has good defoaming and foam inhibiting characteristics and stable quality for long-term storage and use. However, the application mainly realizes the compound effect by adding various additives, and does not indicate how to improve the preparation method to obtain the organosilicon defoamer with better stability and defoaming capability, and the embodiment shows that the defoaming capability of the defoamer is still poor.

In summary, the above documents refer to the silicone defoamer and the preparation method thereof, and often the agent with dispersion effect is added to make the defoamer have better dispersion and better stability in the use process, but the defoaming effect is poor due to the improvement of the dispersion. Otherwise, the stability of the organosilicon defoamer in the form of emulsion is reduced by reducing the emulsifier, so that the stability and the defoaming force cannot be both achieved. Therefore, how to make the defoamer have a certain defoaming capability in the preparation process of the organosilicon defoamer and avoid the decrease of emulsion stability in the emulsification process becomes a technical problem to be solved urgently by the technicians in the field.

Disclosure of Invention

Aiming at the problems that in the organic silicon defoamer, the stability and defoaming efficacy of the defoamer are difficult to balance due to the addition of an emulsifier in the process of preparing emulsion, the first aim of the invention is to provide a composite organosilane defoamer, wherein raw materials such as solid filler, filler treating agent and the like are added in the formula of the composite organosilane defoamer to form a composite with a siloxane compound, so that the prepared defoamer has good dispersibility and stability.

The second object of the present invention is to provide a method for preparing a composite organosilane defoamer, which comprises a filler heat treatment and a secondary emulsification process, and can simultaneously have good defoaming efficacy and stability by generating new chemical bonds and forming double emulsion.

The technical scheme adopted for solving the technical problems is as follows:

A composite organosilicon defoaming agent comprises a siloxane compound, a dispersing agent, an emulsifying agent, a thickening agent, a solid filler, a filler treating agent, a catalyst and an additive, wherein the mass ratio of the solid filler to the siloxane compound is preferably less than or equal to 1:9, and further the solid filler comprises oxides of silicon, magnesium, zinc, aluminum and titanium and silicon resin, preferably fumed silica and silicon resin, and the mass ratio of the fumed silica to the silicon resin is 8~3: 7~3.

The application utilizes the characteristics of small particle size and large specific surface area of the solid filler, and the bubbles are broken under the action of the surface tension of the siloxane compound by absorbing bubbles and impacting the bubbles to cause weak points, and the surface of the solid filler is provided with more than 5% -10% of hydroxyl groups, preferably fumed silica and silicon resin, which both contain a certain amount of silicon hydroxyl bonds, can form hydrogen bonds with water molecules in a water system, and is beneficial to promoting the dispersion and stability of the defoamer. Further, the defoaming effect of the defoamer is better by controlling the mass ratio of the fumed silica to the silicone resin, and when the mass ratio exceeds the mass ratio, the solid filler is mixed for too long, precipitation occurs in the part which is not completely mixed, and when the mass ratio is lower than the mass ratio, the surface tension of the defoamer is reduced.

Preferably, the average particle size of the solid filler is less than or equal to 25 mu m, and when the solid filler is fumed silica and silicone resin, the average particle size of the fumed silica is 5-25 mu m, and the average particle size of the silicone resin is 3-20 mu m.

The particle size of the solid filler is selected to be 5-15 mu m optimally, so that the dispersion degree in foaming liquid is high, the stability is good, and basic defoaming units with extremely small particles and extremely large quantity are formed between the solid filler and the foaming liquid, so that the defoaming agent achieves the optimal defoaming effect.

Preferably, the filler treating agent comprises oleic acid in an amount of 1 to 2.5% by mass of the silicone compound. The solid filler is subjected to waterproof treatment by adding the filler treating agent, so that the solid filler can be effectively prevented from caking, and the dispersibility and uniformity of the mixture are better.

Preferably, the catalyst is 1-3% of the weight of the solid filler, and the catalyst comprises hydrogen-containing silicone oil or a silane coupling agent.

The catalyst is hydrogen-containing silicone oil or a silane coupling agent, wherein hydrophilic groups contained in the catalyst can react with hydroxyl groups in the solid filler, so that the bonding between the solid filler and the silicon-oxygen compound can be further enhanced. The invention makes the dosage of hydrogen-containing silicone oil or silane coupling agent be 1-2.5% of the solid filler, and generally, the smaller the filler particle size is, the larger the surface area is, but the larger the dosage of hydrogen-containing silicone oil or silane coupling agent is, the more the catalyst is used, the economic efficiency is reduced, and the effect is not exerted enough if the dosage is small.

Preferably, the dispersing agent is an aqueous solution of polyvinyl alcohol with an alkalization degree of 54-89 mol%, and the polyvinyl alcohol with a high alkalization degree has lower relative molecular mass and higher hydroxyl functional group content, has extremely strong handleability and biocompatibility, and has poorer handleability.

Preferably, the silicone compound is polydimethylsiloxane, and as a linear random polymer, the polydimethylsiloxane is composed of repeated dimethylsiloxane units, has no branched structure, has excellent stability, electrical insulation and heat resistance, and can be used for a long time within a range of-50 ℃ to 200 ℃.

The preparation method of the composite organic silicon defoamer comprises the following steps:

And S1, filler heat treatment, namely adding the siloxane compound and the solid filler into a reactor, heating the reactor to 150-180 ℃, stirring for 4-7 hours, adding the catalyst, heating to 180-185 ℃, and reacting for 2-7 hours to obtain a first mixed solution.

S2, preparing a siloxane compound, namely cooling the first mixed solution to 60-70 ℃, adding the filler treating agent, maintaining the temperature of the reactor at 50-75 ℃, and continuously stirring for 0.5-1 h to obtain the siloxane compound.

And S3, dispersing and phase inversion, namely adding the dispersing agent into the siloxane compound, maintaining the temperature of the reactor at 60-70 ℃, stirring at the rotation speed of 250-500 r/min, stirring for 0.5h to obtain a siloxane compound dispersion liquid, sequentially adding the emulsifying agent and deionized water into the siloxane compound dispersion liquid, continuously maintaining the temperature of the reactor at 60-70 ℃, stirring at the rotation speed of 10000-15000 r/min, stirring for 0.5-1 h, and phase inversion to obtain a second mixed liquid.

And S4, carrying out secondary emulsification, namely maintaining the temperature of the second mixed solution at 60-70 ℃, supplementing a corresponding amount of deionized water after volatilizing 5-10% of the mass fraction of the deionized water, maintaining the temperature of a reactor at 60-70 ℃, and stirring at the rotation speed of 10000-15000 r/min for 0.5h to obtain an emulsion.

And S5, cooling, namely adding the thickener and the additive into the emulsion, and cooling to room temperature to obtain the organosilicon defoamer.

The surface of solid filler before treatment, such as fumed silica and silicone resin, often has two hydrophilic active groups, namely adjacent hydroxyl groups and isolated hydroxyl groups, and the solid filler and the silicone compound are subjected to heat treatment, wherein the isolated hydroxyl groups are replaced by siloxane groups in the silicone compound, and chemical bonds are generated between the solid filler and the silicone compound. Because the solid filler has small particle size and large specific surface area, the solid filler can adsorb bubbles and impact the bubbles to cause weak points, and promote the bubbles to break under the action of the surface tension of the siloxane compound. Further, the reaction temperature of the heat treatment of the filler is controlled to be 180-185 ℃, preferably 180 ℃, so that a considerable amount of chemical bonds are formed between the solid filler and the siloxane compound, and meanwhile, the hydrogen bonds between the hydroxyl groups and the siloxane groups are converted into chemical bonds, so that the bonding effect between the solid filler and the siloxane compound is enhanced.

After the siloxane compound and the solid filler are prepared into the siloxane compound, the dispersed phase inversion and the first emulsification are carried out, and the aqueous solution is wrapped in the oil phase to form a primary emulsion of water-in-oil, namely a second mixed solution. After that, the second mixed solution is subjected to secondary emulsification, and it should be clear that the term "secondary emulsification" does not refer to the secondary emulsification process simply, and the number of secondary emulsification in the system is not limited in the present invention. In the process, the coating of substances is realized through multiple times of emulsification, the emulsion is converted from a water-in-oil state to an oil-in-water state, and the primary emulsion is coated in a water phase under the actions of high-rotation-speed shearing, evaporation and continuous emulsification by supplementing water, so that a double emulsion structure with both stability and defoaming efficacy is prepared, and the double emulsion structure is suitable for defoaming in a water system and can be dispersed more uniformly.

Preferably, in the step S3, when the main component of the emulsifier is polyvinyl alcohol, the emulsion and the deionized water are first prepared at a concentration of 5%, and then the emulsion is added to the silicone composite dispersion. The emulsifier is prepared into aqueous solution in advance, so that the phenomenon that the solids are dehydrated and etherified to lose solubility is avoided, and the colloid can be better protected, so that the emulsification and secondary emulsification processes are promoted.

Compared with the prior art, the embodiment of the invention has at least the following beneficial effects:

1. When the silicone composite is prepared, the solid filler and the filler treating agent are added, so that the polydimethylsiloxane can be stably dispersed on the surface of a foaming system for a long time, and the persistence and stability of the defoaming effect are improved on the premise of keeping the defoaming performance.

2. According to the invention, before the siloxane compound is prepared, heat treatment of the filler is carried out, the formation of chemical bonds between the siloxane compound and the solid filler is promoted by utilizing high temperature, and the conversion from hydrogen bonds to chemical bonds occurs, so that the defoaming effect and the emulsion stability in the phase inversion process can be effectively improved.

3. The defoaming agent prepared by adopting the secondary emulsification method has a double emulsion structure, is uniformly dispersed in a water system when being used for defoaming, can simultaneously give consideration to stability and defoaming efficacy, has stable structure, and remarkably improves the storage time and the heating stability of the defoaming agent.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The present invention will be described in detail with reference to specific examples.

A compound organic silicon defoamer and a preparation method thereof comprise the following steps:

And S1, filler heat treatment, namely adding a siloxane compound and a solid filler into a reactor, heating the reactor to 150-180 ℃, stirring for 4-7 h, adding a catalyst, heating to 180-185 ℃, and reacting for 2-7 h to obtain a first mixed solution.

The catalyst comprises hydrogen-containing silicone oil or a silane coupling agent, and the catalyst is added after stirring is completed, so that the bonding between the solid filler and the silicone compound can be further enhanced, and the average particle size of the solid filler is limited to be less than or equal to 25 mu m, preferably 5-15 mu m, the particle size of the solid filler is proper, the dispersion degree of the foaming liquid is higher, the stability is better, and basic defoaming units with extremely small particles and extremely large quantity can be formed in the foaming liquid, so that the defoaming agent achieves the optimal defoaming effect.

Further, the silicone compound is selected from polydimethylsiloxane, and when the mass ratio of the solid filler to the polydimethylsiloxane is 1:9 or less, preferably 3:37, 1:9 or 1:24, the defoaming effect can be improved and the precipitation can be reduced.

Further, the solid filler is fumed silica and silicone resin, the mass ratio of the fumed silica to the silicone resin is 8~3: 7~3, and the mass ratio of the fumed silica to the silicone resin is limited to form a proper amount of hydrogen bonds with water molecules, so that the dispersion and stability of the first mixed liquid can be promoted when the solid filler is applied to a water system, and under the action of the solid filler and the filler treating agent, the viscosity of the polydimethylsiloxane in the formula can be regulated or the polydimethylsiloxane with different single viscosities or the two polydimethylsiloxanes with different viscosities are compounded on the premise of not changing the mass, so that the defoamer is not limited by the viscosity and the temperature of a foaming system in the use process, and the influence of the environment on the performance of the defoamer is reduced.

S2, preparing a siloxane compound, namely cooling the first mixed solution to 60-70 ℃, adding a filler treating agent, maintaining the temperature of the reactor at 50-75 ℃, and continuously stirring for 0.5-1 h to obtain the siloxane compound.

In the step, the filler treating agent comprises oleic acid, low-relative molecular weight linear polysiloxane or low-relative molecular weight annular polysiloxane, preferably, the mass of the filler treating agent is 1-2% of that of the siloxane compound, and the filler treating agent can be matched with solid filler to effectively prevent the filler from caking, preferably, after the filler treating agent is added, the temperature of a reactor is kept at 60-70 ℃ for reaction, the emulsifying performance can be maintained at the temperature, the emulsification is difficult to be carried out due to the lower emulsifying temperature, and the formed emulsion is broken due to the higher emulsifying temperature.

And S3, dispersing and inverting, namely adding a dispersing agent into the siloxane compound, wherein the dispersing agent is polyvinyl alcohol with the alkalization degree of 54-89 mol percent, the alkalization degree is preferably 86.0mol percent, the temperature of a reactor is maintained at 60-70 ℃, the stirring rotating speed is 250-500 r/min, and the stirring is carried out for 0.5h, so as to obtain a siloxane compound dispersion liquid. Sequentially adding an emulsifier and deionized water into the siloxane compound dispersion liquid, continuously maintaining the temperature of the reactor at 60-70 ℃, stirring at 10000-15000 r/min, stirring for 0.5-1 h, and inverting to obtain a second mixed liquid.

In the step, the emulsifier can be a low-concentration polyvinyl alcohol aqueous solution, glycerol monostearate, tributyl phosphate, polyether or nonionic surfactant, wherein the nonionic surfactant comprises at least one of sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester, and can reduce interfacial tension and facilitate droplet dispersion, so that the interfacial area increase caused by emulsification is reduced, and the emulsion is further stabilized. The emulsifier and deionized water are added and then reacted at 60-70 ℃, so that the emulsifier can be better contacted with oil-water components, the emulsifying effect is better, the cell structure of organic matters can be destroyed, the mixing effect is accelerated, but the liquid is deteriorated due to the excessively high temperature, and the product quality is affected.

Preferably, the emulsifier and deionized water can be prepared at a concentration of 5%, and then the aqueous solution of the emulsifier is prepared, and the siloxane compound dispersion liquid is added, so that the emulsifier has good film forming property and emulsifying property and can be used as a protective colloid in high polymer emulsification. As the glass transition temperature of the emulsifier (for example, polyvinyl alcohol) is 75-85 ℃, in the practical application process, dehydration etherification, loss of solubility and the like can occur if the emulsifier is directly added in a solid form.

And S4, carrying out secondary emulsification, namely maintaining the temperature of the second mixed solution at 60-70 ℃, supplementing a corresponding amount of deionized water after volatilizing 5-10% of the mass fraction of the deionized water, maintaining the temperature of a reactor at 60-70 ℃, and stirring at the rotation speed of 10000-15000 r/min for 0.5h to obtain an emulsion.

In the step, the secondary emulsification realizes substance encapsulation through multiple emulsification, the first emulsification is to encapsulate aqueous solution in oil phase to form primary emulsion, the multiple emulsification is to continuously generate emulsification through high-rotation-speed shearing, evaporation and water supplementing, the primary emulsion is encapsulated in water phase, and the water-in-oil state is converted into the oil-in-water state, so that double emulsion with both stability and defoaming effect is prepared.

And S5, cooling, namely adding a thickening agent and an additive into the emulsion, and cooling to room temperature to obtain the organosilicon defoamer.

In the step, the thickening agent can be high-concentration polyvinyl alcohol aqueous solution, carboxymethyl cellulose or methyl cellulose, so that the viscosity of a substance system can be improved, and the substance system is kept in a uniform and stable state, and the additive comprises a mould growth inhibitor and an antioxidant, so that the effects of inhibiting fungi, resisting bacteria and resisting oxidation are achieved.

Example 1

S1, adding 9.6g of polydimethylsiloxane, 0.28g of fumed silica and 0.12g of silicone resin into a reactor, heating the reactor to 180 ℃, stirring for 2 hours, adding 0.01g of silane coupling agent in the process, heating to 180 ℃, and reacting for 2 hours.

S2, cooling the content of the reactor to 90 ℃, adding 0.2g of oleic acid into the mixture subjected to the heat treatment of the filler, maintaining the temperature of the reactor at 90 ℃, and continuously stirring for 0.5h to obtain the siloxane compound.

S3, after the dispersing agent is added into the siloxane compound, the temperature of the reactor is maintained at 70 ℃, the stirring speed is 15000r/min, the stirring is carried out for 0.5h, 1.6g of emulsifying agent (Span 80:Tween 80=3:2) is added, 83g of deionized water at 50 ℃ is slowly added, the temperature of the reactor is maintained at 70 ℃, and the stirring speed is 15000r/min, and the stirring lasts for 0.5h.

And S4, maintaining the temperature of the mixture system at 70 ℃, stirring at a low speed for 10min, volatilizing part of water, supplementing 50 ℃ deionized water into the system, maintaining the temperature of the reactor at 70 ℃, and stirring at a speed of 15000r/min for 0.5h to obtain an emulsion.

S5, adding 2g of thickener and 0.1g of mould growth inhibitor into the emulsion, and cooling to room temperature to obtain the organosilicon defoamer.

Examples 2 to 8

Examples 2 to 8 of the present invention are basically the same as example 1, and are implemented according to the technical scheme of the specific embodiment, and the implementation conditions are shown in table 1:

Table 1 conditions for practical implementation of examples 1 to 8

Comparative example 1

Comparative example 1 was essentially the same as the embodiment of example 1, except that the mass ratio between the solid filler and the polydimethylsiloxane in the starting materials was greater than 1:9, and that the emulsification process was a single emulsification, and the specific starting materials and proportions are shown in Table 2.

Comparative example 2

Comparative example 2 is substantially the same as the embodiment of example 1 except that no catalyst and filler treating agent are added, and the emulsification process is one-time emulsification, and specific raw materials and proportions are shown in table 2.

Comparative example 3

Comparative example 3 is substantially the same as the embodiment of example 1 except that no solid filler was added, and specific raw materials and proportions are shown in table 2.

Comparative example 4

Comparative example 4 is substantially the same as the embodiment of example 1 except that the heat treatment of the filler was not performed.

The specific implementation conditions of comparative examples 1 to 2 are shown in Table 2:

Table 2 conditions for practical implementation of comparative examples 1 to 4

Experimental example

The performance test method of the defoamer comprises the following steps:

(1) Foaming evaluation of the defoamer efficacy was performed on a 0.1% by mass fatty alcohol sulfate solution

Calculating a defoaming value:

Defoaming value=100- (100 Σh _t/4h_a)

Wherein:

Sigma h _t -the sum of the foam heights after 1min, 5min, 15min, 30 min;

h _a -foam height at the time of stopping bubbling (i.e., 0 min).

(2) A standard foaming liquid was prepared by adding 100mL of a polyoxyethylene derivative of sorbitol monooleate (Tween-80) in an aqueous solution of 0.1% by mass to a 250mL bottle, dropping 1 drop of a defoaming agent, shaking the bottle over the bottle for 10 minutes, and measuring the foam breaking time.

The results of performance tests of the organosilane defoamers prepared in examples 1 to 7 and comparative examples 1 to 2 are shown in Table 3:

table 3 results of Performance test of organosilane defoamers of examples 1 to 8 and comparative examples 1 to 4

In conclusion, the defoamer prepared by the invention has good stability and dispersibility, and simultaneously maintains good defoaming effect.

The embodiments described above are some, but not all embodiments of the application. The detailed description of the embodiments of the application is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Claims (15)

1. The composite organic silicon defoamer comprises a siloxane compound, a dispersing agent, an emulsifying agent and a thickening agent, and is characterized by further comprising a solid filler, a filler treating agent, a catalyst and an additive.

2. A composite silicone defoamer of claim 1, wherein the mass ratio of the solid filler to the silicone compound is less than or equal to 1:9.

3. A composite silicone defoamer according to claim 1 or 2, wherein the solid filler comprises oxides of silicon, magnesium, zinc, aluminum, titanium and silicone.

4. A composite silicone defoamer according to claim 3, wherein the solid filler is fumed silica and silicone resin, and the mass ratio of the fumed silica to the silicone resin is 8~3: 7~3.

5. A composite silicone defoamer according to claim 1 or 2, wherein the solid filler has an average particle size of 25 μm or less.

6. The composite organic silicon defoamer of claim 4, wherein the fumed silica has an average particle size of 5-25 μm and the silicone resin has an average particle size of 3-20 μm.

7. The composite organic silicon defoamer of claim 1, wherein the filler treating agent is 1-3% of the mass of the silicone compound.

8. A complex silicone defoamer of claim 1 or 7, wherein said filler treating agent comprises oleic acid.

9. The composite organic silicon defoamer of claim 1, wherein the catalyst is 1-2.5% of the weight of the solid filler.

10. A complex silicone defoamer according to claim 1 or 9, wherein the catalyst comprises hydrogen-containing silicone oil or a silane coupling agent.

11. The composite organic silicon defoamer of claim 1, wherein the dispersant is an aqueous solution of polyvinyl alcohol with an alkalization degree of 54-89 mol%.

12. A complex silicone defoamer according to claim 1, the method is characterized in that the siloxane compound is polydimethylsiloxane.

13. A method for preparing the composite silicone defoamer of any of claims 1 to 12, comprising emulsification, wherein the solid filler is subjected to heat treatment, and the emulsification is secondary emulsification.

14. The method for preparing the composite organic silicon defoamer according to claim 13, comprising the following steps:

S1, filler heat treatment, namely adding the siloxane compound and the solid filler into a reactor, heating the reactor to 150-180 ℃, stirring for 4-7 hours, adding the catalyst, heating to 180-185 ℃, and reacting for 2-7 hours to obtain a first mixed solution;

S2, preparing a siloxane compound, namely cooling the first mixed solution to 60-70 ℃, adding the filler treating agent, maintaining the temperature of a reactor at 50-75 ℃, and continuously stirring for 0.5-1 h to obtain the siloxane compound;

S3, dispersing and inverting, namely after the dispersing agent is added into the siloxane compound, maintaining the temperature of a reactor at 60-70 ℃, stirring at a rotational speed of 250-500 r/min, stirring for 0.5h to obtain a siloxane compound dispersion liquid, sequentially adding the emulsifying agent and deionized water into the siloxane compound dispersion liquid, continuously maintaining the temperature of the reactor at 60-70 ℃, stirring at a rotational speed of 10000-15000 r/min, stirring for 0.5-1 h, inverting to obtain a second mixed liquid;

S4, secondary emulsification, namely maintaining the temperature of the second mixed solution at 60-70 ℃, supplementing a corresponding amount of deionized water after volatilizing 5-10% of the mass fraction of the deionized water, maintaining the temperature of a reactor at 60-70 ℃, and stirring at a rotating speed of 10000-15000 r/min for 0.5h to obtain an emulsion;

And S5, cooling, namely adding the thickening agent and the additive into the emulsion, and cooling to room temperature to obtain the organosilicon defoamer.

15. The method of claim 14, wherein in S3, the emulsifier and deionized water are mixed at a concentration of 5%, and the aqueous emulsifier solution is added to the silicone composite dispersion.