Defoaming aid, process for its preparation and use thereof

Abstract

The application discloses a defoaming aid, and raw materials for preparation include, in weight parts, 65-85 parts of partially hyperbranched modified polyether, 3-20 parts of polyether modified hydrogen-containing silicone oil, and 5-15 parts of inorganic filler modified siloxane. The partially hyperbranched modified polyoxypropylene polyoxyethylene block copolymer with a weight average molecular weight of 2000-6000 Da is adopted, the contact area between the defoaming agent and the foam is increased, the defoaming capacity is further improved, and the influence of the system with high surface tension on the defoaming performance is reduced. The allyl polyether modified low hydrogen-containing silicone oil is adopted, the diffusion and permeation capacity of the defoaming agent is enhanced, the defoaming agent can quickly reach the foam part, and the defoaming speed is improved. Meanwhile, the foam suppressing performance of the defoaming agent is improved, and the defoaming duration is prolonged.

Description

Technical Field

[0001] This invention relates to an antifoaming agent, its preparation method and application, and specifically to the field of coating composition additives, specifically CO9D. Background Technology

[0002] Defoamers play a crucial role in resin coatings, inks, and wastewater treatment. The presence of air bubbles in liquid raw material mixtures affects the surface finish after curing and can impact subsequent processing equipment in wastewater treatment. Therefore, the research and development of defoamers is essential to eliminate the impact of air bubbles on production. Silicone-based defoamers have good defoaming activity but suffer from the drawback of pinholes. Polyether-based defoamers work by encapsulating air bubbles in water containing surfactants, which emulsify and solubilize the bubbles. These surfactants have low surface tension. In systems with low surface tension, especially in resin systems containing leveling agents and surfactants, the defoaming performance of polyether defoamers is significantly reduced. Therefore, improving the defoaming activity, speed, duration, and persistence of defoaming and foam suppression of polyether defoamers is crucial.

[0003] Chinese invention patent CN202010006256.9 discloses an organosilicon defoamer for use in water-based coatings and its preparation method. By using a symmetrically structured end-group isomeric alcohol ether-terminated polyether modified polysiloxane, the defoamer exhibits lower surface tension, further enhancing its defoaming performance and overcoming drawbacks such as the tendency to cause pinholes. However, its foam suppression and defoaming effects are relatively short-lived and cannot achieve a long-lasting defoaming effect. Chinese invention patent CN201810166357.5 discloses a defoamer for coatings and inks and its preparation method. It prepares a polyether-modified silicone oil by hydrosilylation reaction of hydrogen-containing silicone oil with EO / PO block or random allyl polyether.

[0004] By adjusting the molar ratio and molecular weight of polyether EO / PO, the resulting defoamer has a short defoaming time, a long foam suppression time, and no oil floating phenomenon. However, it has poor storage stability and is prone to stratification under high temperature conditions. Summary of the Invention

[0005] In order to improve the defoaming activity of polyether defoamers, increase the defoaming speed of defoamers, prolong defoaming, inhibit foaming persistence, and increase the stability of defoamers, the first aspect of the present invention provides a defoaming aid, the raw materials for which, by weight, include: 65-85 parts of partially hyperbranched modified polyether, 3-20 parts of polyether-modified hydrogen-containing silicone oil, and 5-15 parts of inorganic filler-modified siloxane.

[0006] In a preferred embodiment, the partially hyperbranched modified polyether is a partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer, selected from one or a combination of several of partially hyperbranched modified propylene glycol-polyoxypropylene-polyoxyethylene block polyether, partially hyperbranched modified glycerol-polyoxypropylene-polyoxyethylene block polyether, and partially hyperbranched modified trimethylolpropane-polyoxypropylene-polyoxyethylene block polyether.

[0007] In one preferred embodiment, the raw material for preparing the partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer includes a polyoxypropylene-polyoxyethylene block copolymer with a weight-average molecular weight of 2000-6000 Da.

[0008] As a preferred embodiment, the method for preparing the partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer includes the following steps:

[0009] The polyoxypropylene-polyoxyethylene block copolymer was mixed with isocyanate, heated to 80-90℃, and kept at that temperature for 2-4 hours to obtain partially hyperbranched modified polyoxypropylene-polyoxyethylene block polyether.

[0010] In a preferred embodiment, the mass ratio of the polyoxypropylene-polyoxyethylene block copolymer to the isocyanate is (280-320):(2-6).

[0011] In a preferred embodiment, the modified propylene glycol polyoxypropylene polyoxyethylene block polyether is selected from one or a combination of several of PPG2000, polyether L61, polyether L62, and L64.

[0012] In a preferred embodiment, the weight-average molecular weight of the propylene glycol polyoxypropylene polyoxyethylene block polyether is preferably 2000-4000 Da.

[0013] In a preferred embodiment, the weight-average molecular weight of the glycerol polyoxypropylene polyoxyethylene block polyether is preferably 3000-5000 Da.

[0014] In a preferred embodiment, the isocyanate is a diisocyanate selected from one or more of HDI, MDI, IPDI, TDI, HMDI, and LDI.

[0015] During the experiment, the applicant discovered that when polyether-based defoamers are applied to high-viscosity systems, the surface tension of the system is high due to interference from surfactants such as leveling agents or emulsifiers, resulting in insignificant defoaming effects and a significant increase in the amount of defoamer required. The applicant found that by partially hyperbranching isocyanate into polyoxypropylene-polyoxyethylene block copolymers, the modified product is less susceptible to compatibilization by leveling agents and surfactants, thus improving its resistance to leveling agents and surfactant interference. The applicant speculates that the possible reason is that after partially hyperbranching isocyanate into polyoxypropylene-polyoxyethylene block copolymers with a molecular weight of 3000-5000, diisocyanate forms more branching points on the polyoxypropylene-polyoxyethylene block copolymer, making the molecular chains less prone to entanglement. Furthermore, the abundant terminal functional groups increase the contact opportunities and range between the hyperbranched modified polyether and the foam, thereby improving the defoaming effect, increasing the defoaming ability, and reducing the amount of defoamer required.

[0016] In a preferred embodiment, the polyether-modified hydrogen-containing silicone oil is a polyether-modified low-hydrogen-content silicone oil, and the polyether-modified low-hydrogen-content silicone oil is an allyl polyether-modified low-hydrogen-content silicone oil.

[0017] In a preferred embodiment, the raw materials for preparing the allyl polyether-modified low-hydrogen silicone oil include low-hydrogen silicone oil and allyl polyether, wherein the low-hydrogen silicone oil has the structural formula (CH3)3SiO[(CH3)2SiO]. x [(CH3)HSiO] y The allyl polyether of Si(CH3)3 has the structural formula CH2=CHCH2O(OC2H4). m (OC3H6) n R is selected from H, n-butyl, and acetyl; where x is 30-120, y is 3-15, m is 1-50, and n is 1-50.

[0018] In a preferred embodiment, x is 50-100, y is 5-10, m is 10-25, and n is 1-20.

[0019] As a preferred embodiment, the preparation method of the allyl polyether modified low-hydrogen silicone oil includes the following steps:

[0020] Low-hydrogen silicone oil and allyl polyether are mixed and added to a reaction vessel. The mixture is stirred and heated to 90-140℃. Chloroplatinic acid catalyst is added and the reaction is carried out for 2-5 hours to obtain allyl polyether modified low-hydrogen silicone oil.

[0021] In a preferred embodiment, the mass ratio of the low-hydrogen silicone oil to the allyl polyether is (100-150):(250-350).

[0022] In a preferred embodiment, the chloroplatinic acid catalyst is introduced into the system at an overall concentration of 200-500 ppm.

[0023] During the experiment, the applicant discovered that traditional polyether defoamers, due to their high surface tension, are difficult to spread on the foam surface, thus failing to effectively exert their defoaming performance. By modifying low-hydrogen-content dimethyl silicone oil with butyl-terminated allyl polyether, the surface tension of the modified polysiloxane was reduced. The foam surface, which is coated with an aqueous solution of surfactants, contains hydrophobic substances such as compatibilizing oils, hydrocarbons, and alcohol esters, resulting in low surface tension. After the surface tension of the modified hydrogen-containing silicone oil decreased, it spread more easily on the surface, increasing the permeability of hydrophobic substances and accelerating their reach to the foam surface. This allows for rapid defoaming and improves the defoaming speed.

[0024] In a preferred embodiment, the raw materials for preparing the inorganic filler-modified siloxane include inorganic fillers, wherein the specific surface area of ​​the inorganic fillers is 120-300 m². 2 / g, wherein the particle size of the inorganic filler is 0.3-10μm.

[0025] In a preferred embodiment, the inorganic filler has a specific surface area of ​​120-180 m². 2 / g particle size of 2-10μm and specific surface area of ​​240-300m² 2 / g of a combination of particles with a diameter of 0.3-2μm.

[0026] In a preferred embodiment, the specific surface area is 120-180 m². 2 / g particle size of 2-10μm and specific surface area of ​​240-300m² 2 The weight ratio of inorganic fillers with a particle size of 0.3-2μm is (15-30):(3-10).

[0027] In a preferred embodiment, the inorganic filler is selected from one or a combination of several of the following: silica, bentonite, magnesium aluminum silicate, sepiolite, and attapulgite.

[0028] In a preferred embodiment, the inorganic filler is silica.

[0029] In a preferred embodiment, the inorganic filler-modified siloxane is an inorganic filler-modified polydimethylsiloxane, wherein the polydimethylsiloxane has a viscosity of 300-3000 mPa·s at 25°C.

[0030] As a preferred embodiment, the preparation method of the inorganic filler-modified siloxane includes the following steps:

[0031] Inorganic fillers with different particle sizes and specific surface areas are mixed with polydimethylsiloxane and added to a reactor. The mixture is activated at 120℃-180℃ for 3-8 hours to obtain inorganic filler-modified siloxane.

[0032] In a preferred embodiment, the weight ratio of the inorganic filler to polydimethylsiloxane is (20-40):(260-280).

[0033] During the experiment, the applicant found that polyether-based defoamers had good defoaming performance, but their defoaming and foam-suppressing persistence was poor. The applicant improved the defoaming and foam-suppressing persistence of the defoamer by modifying polydimethylsiloxane with silica. The applicant speculates that the possible reason is the use of a specific surface area of ​​120-180 m² / g. 2 / g particle size of 2-10μm and specific surface area of ​​240-300m² 2 A combination of precipitated silica with a particle size of 0.5–2 μm modifies polydimethylsiloxane. Silica of different particle sizes and specific surface areas forms a three-dimensional network structure with adsorption capacity, which can adsorb air bubbles. Furthermore, the different particle sizes and specific surface areas of the silica can attack the air bubbles, creating weak points that cause the bubbles to burst under the action of polydimethylsiloxane. The three-dimensional network structure formed by the silica of different particle sizes and specific surface areas exhibits uniform stress and is not easily destroyed, thus providing long-term defoaming and foam-suppressing effects, extending the duration of the defoamer's defoaming and foam-suppressing properties.

[0034] During the experiment, the applicant found that when modified polyether, modified hydrogen-containing silicone oil, and silica-modified polydimethylsiloxane were used in a weight ratio of (65-85):(3-20):(5-15), the resulting defoamer could be stored stably at high temperatures and was not prone to stratification. The applicant speculated that the possible reason was that at the preferred weight ratio, the system had more branches, and the silica-modified polydimethylsiloxane had greater resistance to sedimentation, making the system less prone to stratification. However, when the preferred weight ratio was exceeded, the resistance to sedimentation decreased at high temperatures, making the system more prone to stratification and reducing stability.

[0035] A second aspect of the present invention provides a method for preparing an antifoaming agent, comprising the following steps:

[0036] Modified polyether, modified hydrogen-containing silicone oil, and modified siloxane are mixed in a dispersion tank in a certain proportion and dispersed evenly to obtain the defoaming aid product.

[0037] A third aspect of the present invention provides an application of an antifoaming agent in aqueous resins.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The defoaming agent of the present invention is a partially hyperbranched modified polyoxypropylene and polyoxyethylene block copolymer with a weight average molecular weight of 2000-6000 Da, which increases the contact area between the defoaming agent and the foam, further improves the defoaming ability, and reduces the impact on the defoaming performance in a system with high surface tension.

[0040] (2) The defoaming agent described in this invention uses allyl polyether modified low-hydrogen silicone oil to enhance the diffusion and penetration ability of the defoaming agent, which can enable the defoaming agent to reach the foam area quickly and improve the defoaming speed.

[0041] (3) The defoaming agent described in this invention has a specific surface area of ​​120-180 m². 2 / g Particle size of 2-10μm and specific surface area of ​​240-300m² 2 The combination of precipitated silica with a particle size of 0.5-2μm modified polydimethylsiloxane with a viscosity of 300-3000mPa.s at 25℃, improving the defoaming performance of the defoamer and prolonging the defoaming duration.

[0042] (4) The defoaming agent described in this invention, modified polyether, modified hydrogen-containing silicone oil, and modified siloxane are used in a weight ratio of (65-85):(3-20):(5-15). The resulting defoaming agent has stable performance and does not separate into layers after being stored for 7 days at 60°C.

[0043] (5) The defoaming agent described in this invention, when applied to aqueous resin liquid, reduces the amount of defoaming agent used, shortens the defoaming time, improves the defoaming stability, and prolongs the defoaming and foam-suppressing durability of the defoaming agent. Detailed Implementation

[0044] Example 1

[0045] An antifoaming agent, the raw materials for which are prepared by weight include: 75 parts of partially hyperbranched modified polyether, 10 parts of polyether-modified hydrogen-containing silicone oil, and 10 parts of inorganic filler-modified siloxane.

[0046] The partially hyperbranched modified polyether is a partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer, and the preparation method includes the following steps:

[0047] A polyoxypropylene-polyoxyethylene block copolymer was mixed with isocyanate, heated to 85°C, and kept at that temperature for 3 hours to obtain a partially hyperbranched modified polyoxypropylene-polyoxyethylene block polyether.

[0048] The polyoxypropylene-polyoxyethylene block copolymer is a propylene glycol-polyoxypropylene-polyoxyethylene block polyether (in which the polyoxyethylene segment accounts for 15% of the total molecular weight) with a molecular weight of 3150 Da. The propylene glycol-polyoxypropylene-polyoxyethylene block polyether was purchased from Jiangsu Haian Petrochemical, and its model number is N33025.

[0049] The mass ratio of the polyoxypropylene-polyoxyethylene block copolymer to the isocyanate is 320:6.

[0050] The isocyanate is TDI (2,4-dimethylbenzene diisocyanate).

[0051] The polyether-modified hydrogen-containing silicone oil is an allyl polyether-modified low-hydrogen-content silicone oil, and the preparation method of the allyl polyether-modified low-hydrogen-content silicone oil includes the following steps:

[0052] Low-hydrogen silicone oil and allyl polyether were mixed and added to a reaction vessel. The mixture was stirred and heated to 120°C. Chloroplatinic acid catalyst was added and the reaction was carried out for 4 hours to obtain allyl polyether modified low-hydrogen silicone oil.

[0053] The structural formula of the low-hydrogen-content silicone oil is (CH3)3SiO[(CH3)2SiO]. 60 The [(CH3)HSiO]6Si(CH3)3 was purchased from Jiangxi Junhui New Materials Co., Ltd., model number JH-2109; the structural formula of the butyl-terminated allyl polyether is CH2=CHCH2O(C2H4O). 16 (C3H6O) 16 C4H9, purchased from Zhejiang Lvkean New Materials Co., Ltd., model number HMS-274M.

[0054] The mass ratio of the low-hydrogen silicone oil to the allyl polyether is 150:350.

[0055] After the chloroplatinic acid catalyst is introduced into the system, the overall concentration in the system is 300 ppm.

[0056] The preparation method of the inorganic filler-modified siloxane includes the following steps:

[0057] Inorganic fillers with different particle sizes and specific surface areas were mixed with polydimethylsiloxane and added to a reactor. The mixture was activated at 170°C for 4 hours to obtain inorganic filler-modified siloxane.

[0058] The inorganic filler has a specific surface area of ​​120 m². 2 / g Particle size of 2-10μm and specific surface area of ​​240m² 2 A combination of silica particles with a particle size of 0.5-2μm, in a weight ratio of 30:10.

[0059] The inorganic filler-modified siloxane is inorganic filler-modified polydimethylsiloxane, which has a viscosity of 350 mPa·s at 25°C and was purchased from Dow Corning, model number: PMX-50-350.

[0060] The weight ratio of the inorganic filler to polydimethylsiloxane is 40:260.

[0061] A method for preparing an antifoaming agent includes the following steps:

[0062] Partially hyperbranched modified polyether, polyether-modified hydrogen-containing silicone oil, and inorganic filler-modified siloxane are mixed in a dispersion tank in a certain proportion and dispersed evenly to obtain the defoaming aid product.

[0063] Example 2

[0064] An antifoaming agent, the raw materials for which are prepared by weight include: 65 parts of partially hyperbranched modified polyether, 5 parts of polyether-modified hydrogen-containing silicone oil, and 5 parts of inorganic filler-modified siloxane.

[0065] The partially hyperbranched modified polyether is a partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer, and the preparation method includes the following steps:

[0066] A polyoxypropylene-polyoxyethylene block copolymer was mixed with isocyanate, heated to 90°C, and kept at that temperature for 4 hours to obtain a partially hyperbranched modified polyoxypropylene-polyoxyethylene block polyether.

[0067] The polyoxypropylene-ethylene block copolymer is a glycerol-polyoxypropylene-ethylene block polyether with a molecular weight of 4800 Da. The glycerol-polyoxypropylene-ethylene block polyether was purchased from Zhejiang Huangma Technology Co., Ltd., and its model number is HML-323R.

[0068] The mass ratio of the polyoxypropylene-polyoxyethylene block copolymer to the isocyanate is 300:2.4.

[0069] The isocyanate is HDI (hexamethylene diisocyanate).

[0070] The polyether-modified hydrogen-containing silicone oil is an allyl polyether-modified low-hydrogen-content silicone oil, and the preparation method of the allyl polyether-modified low-hydrogen-content silicone oil includes the following steps:

[0071] Low-hydrogen silicone oil and allyl polyether were mixed and added to a reaction vessel. The mixture was stirred and heated to 120°C. Chloroplatinic acid catalyst was added and the reaction was carried out for 4 hours to obtain allyl polyether modified low-hydrogen silicone oil.

[0072] The structural formula of the low-hydrogen-content silicone oil is (CH3)3SiO[(CH3)2SiO]. 73 [(CH3)HSiO] 10Si(CH3)3 was purchased from Jiangxi Junhui New Materials Co., Ltd., model number: JH-2107; the structural formula of the butyl-terminated allyl polyether is CH2=CHCH2O(C2H4O). 12 (C3H6O) 10 H, purchased from Zhejiang Kaide Chemical Co., Ltd., model: KD-F6.

[0073] The mass ratio of the low-hydrogen silicone oil to the allyl polyether is 120:250.

[0074] After the chloroplatinic acid catalyst is introduced into the system, the overall concentration in the system is 250 ppm.

[0075] The preparation method of the inorganic filler-modified siloxane includes the following steps:

[0076] Inorganic fillers with different particle sizes and specific surface areas were mixed with polydimethylsiloxane and added to a reactor. The mixture was activated at 170°C for 3 hours to obtain inorganic filler-modified siloxane.

[0077] The inorganic filler has a specific surface area of ​​160 m². 2 / g Particle size of 2-10μm (purchased from Beijing Aerospace Saide, model 480P) and specific surface area of ​​300m² 2 A mixture of 0.3-1μm silica (purchased from Tokuyama Chemical, model DM-10S) in a weight ratio of 20:5.

[0078] The inorganic filler-modified siloxane is inorganic filler-modified polydimethylsiloxane, which has a viscosity of 1000 mPa·s at 25°C and was purchased from Rongli Chemical Co., Ltd., model 1000cst.

[0079] The weight ratio of the inorganic filler to polydimethylsiloxane is 25:275.

[0080] A method for preparing an antifoaming agent includes the following steps:

[0081] Partially hyperbranched modified polyether, polyether-modified hydrogen-containing silicone oil, and inorganic filler-modified siloxane are mixed in a dispersion tank in a certain proportion and dispersed evenly to obtain the defoaming aid product.

[0082] Example 3

[0083] An antifoaming agent, the raw materials for which are prepared by weight include: 85 parts of partially hyperbranched modified polyether, 20 parts of polyether-modified hydrogen-containing silicone oil, and 15 parts of inorganic filler-modified siloxane.

[0084] The partially hyperbranched modified polyether is a partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer, and the preparation method includes the following steps:

[0085] A polyoxypropylene-polyoxyethylene block copolymer was mixed with isocyanate, heated to 90°C, and kept at that temperature for 4 hours to obtain a partially hyperbranched modified polyoxypropylene-polyoxyethylene block polyether.

[0086] The polyoxypropylene-ethylene block copolymer is a trimethylolpropane polyoxypropylene-ethylene block polyether (in which the polyoxyethylene segment accounts for 20% of the total molecular weight) with a molecular weight of 4000 Da. The trimethylolpropane polyoxypropylene-ethylene block polyether was purchased from Jiangsu Haian Petrochemical, and its type is 330N.

[0087] The mass ratio of the polyoxypropylene-polyoxyethylene block copolymer to the isocyanate is 280:4.9.

[0088] The isocyanate is IPDI (isophorone diisocyanate).

[0089] The polyether-modified hydrogen-containing silicone oil is an allyl polyether-modified low-hydrogen-content silicone oil, and the preparation method of the allyl polyether-modified low-hydrogen-content silicone oil includes the following steps:

[0090] Low-hydrogen silicone oil and allyl polyether were mixed and added to a reaction vessel. The mixture was stirred and heated to 130°C. Chloroplatinic acid catalyst was added and the reaction was carried out for 5 hours to obtain allyl polyether modified low-hydrogen silicone oil.

[0091] The structural formula of the low-hydrogen-content silicone oil is (CH3)3SiO[(CH3)2SiO]. 40 The butyl-terminated allyl polyether [(CH3)HSiO]6Si(CH3)3, purchased from Jiangxi Junhui New Materials Co., Ltd., model number: JH-2105, has the structural formula CH2=CHCH2O(C2H4O). 25 (C3H6O)9H, purchased from Royal Madrid Technology Group Co., Ltd., model number: HMS-254M.

[0092] The mass ratio of the low-hydrogen silicone oil to the allyl polyether is 100:350.

[0093] After the chloroplatinic acid is introduced into the system, the overall concentration in the system is 500 ppm.

[0094] The preparation method of the inorganic filler-modified siloxane includes the following steps:

[0095] Inorganic fillers with different particle sizes and specific surface areas were mixed with polydimethylsiloxane and added to a reactor. The mixture was activated at 160°C for 5 hours to obtain inorganic filler-modified siloxane.

[0096] The inorganic filler has a specific surface area of ​​180 m². 2 / g Particle size of 2-10μm (purchased from Changsha Lingwei, model SPH-5) and specific surface area of ​​300m² 2 A mixture of silica with a particle size of 0.5-2μm (purchased from Tokuyama Chemical, model DM-20S) in a weight ratio of 17:3.

[0097] The inorganic filler-modified siloxane is inorganic filler-modified polydimethylsiloxane, which has a viscosity of 3000 mPa·s at 25°C and was purchased from Huangshan Qiangli Chemical Co., Ltd., model DM3000.

[0098] A method for preparing an antifoaming agent includes the following steps:

[0099] Partially hyperbranched modified polyether, polyether-modified hydrogen-containing silicone oil, and inorganic filler-modified siloxane are mixed in a dispersion tank in a certain proportion and dispersed evenly to obtain the defoaming aid product.

[0100] Comparative Example 1

[0101] An antifoaming agent, the specific steps are the same as in Example 1, except that the inorganic filler modified siloxane is replaced with unmodified polydimethylsiloxane.

[0102] Comparative Example 2

[0103] An antifoaming agent, the specific steps are the same as in Example 1, the difference being that the raw materials for preparation include, by weight, 60 parts of partially hyperbranched modified polyether, 20 parts of polyether-modified hydrogen-containing silicone oil, and 20 parts of inorganic filler-modified siloxane.

[0104] Comparative Example 3

[0105] An antifoaming agent, the specific steps are the same as in Example 1, the difference being that the inorganic filler has a specific surface area of ​​120 m². 2 / g of silica with a particle size of 2-10μm.

[0106] Performance testing

[0107] 1. Defoaming time test: Add 40g of 20wt% aqueous solution of Pingpingjia O-25 and 40g of red powder to 20g of aqueous resin mother liquor. After stirring until foaming occurs, add 0.2g of the prepared defoamer, continue stirring until homogeneous, and observe the defoaming time. The aqueous resin mother liquor was purchased from Hefei Dibang Nanotechnology Co., Ltd., model TJ-8293.

[0108] 2. Storage stability test: After maintaining the temperature at 60°C for 7 days in a constant temperature chamber, observe whether stratification occurs.

[0109] 3. Defoaming Durability Test: Add 40g of 20wt% Pingpingjia O-25 aqueous solution and 40g of red powder to 20g of aqueous resin mother liquor. After stirring to remove bubbles, add 0.3g of the prepared defoaming agent, start stirring, and continuously stir at 1500 rpm for 15 minutes. Stop stirring and measure the height of the foam rise in the container with a ruler. The smaller the foam rise height, the better the defoaming durability. The aqueous resin mother liquor was purchased from Hefei Dibang Nanotechnology Co., Ltd., model TJ-8293.

[0110] The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113]

Claims

1. An antifoaming agent, characterized in that, The raw materials for preparation include, by weight: 65-85 parts of partially hyperbranched modified polyether, 3-20 parts of polyether-modified hydrogen-containing silicone oil, and 5-15 parts of inorganic filler-modified siloxane. The partially hyperbranched modified polyether is a partially hyperbranched modified polyoxypropylene polyoxyethylene block copolymer. The raw materials for preparation include polyoxypropylene polyoxyethylene block copolymer, and the weight average molecular weight of polyoxypropylene polyoxyethylene block copolymer is 2000-6000 Da. The preparation method of partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer includes the following steps: The polyoxypropylene-polyoxyethylene block copolymer was mixed with isocyanate, heated to 80-90℃, and kept at the temperature for 2-4 hours to obtain partially hyperbranched modified polyoxypropylene-polyoxyethylene block polyether. The raw materials for preparing the inorganic filler-modified siloxane include inorganic fillers, wherein the inorganic fillers have a specific surface area of ​​120-180 m². 2 / g Particle size of 2-10μm and specific surface area of ​​240-300 m² 2 / g of a combination of particles with a diameter of 0.3-2μm.

2. The defoaming agent according to claim 1, characterized in that, The partially hyperbranched modified polyoxypropylene-polyoxyethylene block copolymer is selected from one or a combination of several of the following: partially hyperbranched modified propylene glycol polyoxypropylene-polyoxyethylene block ether, partially hyperbranched modified glycerol polyoxypropylene-polyoxyethylene block ether, and partially hyperbranched modified trimethylolpropane polyoxypropylene-polyoxyethylene block ether.

3. The defoaming agent according to claim 1, characterized in that, The polyether-modified hydrogen-containing silicone oil is a polyether-modified low-hydrogen-content silicone oil, and the polyether-modified low-hydrogen-content silicone oil is an allyl polyether-modified low-hydrogen-content silicone oil.

4. The defoaming agent according to claim 3, characterized in that, The raw materials for preparing the allyl polyether-modified low-hydrogen silicone oil include low-hydrogen silicone oil and allyl polyether. The structural formula of the low-hydrogen silicone oil is (CH3)3SiO[(CH3)2SiO]. x [(CH3)HSiO] y Si(CH3)3, the allyl polyether has the structural formula CH2=CHCH2O(OC2H4). m (OC3H6) n R is selected from H, n-butyl, and acetyl; where x is 30-120, y is 3-15, m is 1-50, and n is 1-50.

5. The defoaming agent according to claim 1, characterized in that, The inorganic filler is selected from one or a combination of several of the following: silica, bentonite, magnesium aluminum silicate, sepiolite, and attapulgite.

6. The defoaming agent according to claim 1, characterized in that, The inorganic filler-modified siloxane is inorganic filler-modified polydimethylsiloxane, and the polydimethylsiloxane has a viscosity of 300-3000 mPa·s at 25°C.

7. A method for preparing the defoaming agent according to any one of claims 1-6, characterized in that, Includes the following steps: Modified polyether, modified hydrogen-containing silicone oil, and modified siloxane are mixed in a dispersion tank in a certain proportion and dispersed evenly to obtain the defoaming aid product.

8. The application of an antifoaming agent according to any one of claims 1-6, characterized in that, It is used in water-based resins.

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