Customized modification method for nanocrystalline magnetic core encapsulation material

Abstract

This invention discloses a modification method for nanocrystalline magnetic core encapsulation materials. The method includes: S1: surface functionalization modification of nano-silica and boron nitride nanosheets by grafting amino and epoxy groups, respectively; S2: blending and dispersing the modified inorganic nanofiller with low-viscosity bisphenol A type epoxy resin, flexible epoxy resin diluent, latent curing agent, and coupling agent under high shear force to form a uniform and stable modified epoxy resin composition; S3: plasma cleaning and activation treatment of the nanocrystalline magnetic core; S4: encapsulating the modified epoxy resin composition on the surface of the magnetic core using a vacuum pressure impregnation process, followed by programmed temperature curing. This invention significantly improves the mechanical strength, thermal conductivity, and heat resistance of the encapsulation layer and reduces the high-frequency dielectric constant and loss by constructing an organic-inorganic interpenetrating network and interface reinforcement.

Description

Technical Field

[0001] This invention relates to the field of nanocrystalline magnetic cores, and more particularly to a customized modification method for nanocrystalline magnetic core packaging materials. Background Technology

[0002] Nanocrystalline soft magnetic materials possess excellent properties such as high saturation magnetic induction, high permeability, and low high-frequency loss, and are widely used in power electronic devices such as high-frequency transformers, common-mode inductors, and electromagnetic interference filters. However, nanocrystalline magnetic cores are typically composed of microcrystals with a thickness of about 20-30 nm. Their large specific surface area and high activity make them highly susceptible to corrosion from moisture, oxygen, salt spray, and mechanical stress in the environment, leading to deterioration of magnetic properties, decrease in insulation resistance, and reduced reliability. Therefore, effective surface encapsulation protection is essential.

[0003] Currently, the industry generally uses epoxy resin to impregnate or pot the magnetic core. However, traditional epoxy resin encapsulation materials have the following inherent defects: (1) The coefficient of thermal expansion is usually 60-80 ppm / ℃, which is much higher than that of nanocrystalline magnetic cores. This generates large internal stress during temperature cycling, which may cause the encapsulation layer to crack or peel off from the surface of the magnetic core; (2) Poor thermal conductivity, which is not conducive to the dissipation of heat generated by the magnetic core when it is running at high power density, resulting in increased local temperature rise and unstable magnetic properties; (3) Limited heat resistance, which is prone to thermal aging when working at temperatures above 100℃ for a long time, resulting in decreased mechanical strength and bonding strength; (4) High dielectric constant and dielectric loss at high frequencies, which will increase the parasitic capacitance and loss of the device and affect high frequency performance.

[0004] To address these issues, existing technologies attempt to add inorganic fillers, such as ordinary silica and alumina, to epoxy resins. However, conventional fillers exhibit weak interfacial bonding with the resin matrix, and at high addition levels, they are prone to agglomeration, leading to a sharp increase in viscosity, deterioration in processability, and limited or even worsening of high-frequency dielectric properties. Developing a high-performance nanocrystalline magnetic core encapsulation material without significantly increasing process complexity and cost has become a pressing technical challenge in this field.

[0005] Therefore, this invention proposes a customized modification method for nanocrystalline magnetic core packaging materials. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a customized modification method for nanocrystalline magnetic core packaging materials.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A customized modification method for nanocrystalline magnetic core packaging materials includes the following steps: S1: Surface functionalization modification of nano-silica and boron nitride nanosheets by grafting amino and epoxy groups, respectively; S2: The modified inorganic nanofiller is blended and dispersed with low-viscosity bisphenol A type epoxy resin, flexible epoxy resin diluent, latent curing agent and coupling agent under high shear force to form a uniform and stable modified epoxy resin composition. S3: Plasma cleaning and activation treatment of nanocrystalline magnetic core; S4: The modified epoxy resin composition is encapsulated on the surface of the magnetic core using a vacuum pressure impregnation process, and then cured by programmed temperature rise.

[0008] Preferably, in the modification method: Step S1 is as follows: Weigh nano-silica and boron nitride nanosheets separately, and ultrasonically disperse them in a first anhydrous ethanol solution; add 1-3% by mass of -aminopropyltriethoxysilane to the nano-silica dispersion, and reflux at 60-80℃ for 4-6 hours. After the reaction is completed, centrifuge, wash, and dry to obtain amino-modified nano-silica; add 2-4% by mass of -(2,3-epoxypropoxy)propyltrimethoxysilane to the boron nitride nanosheet dispersion, and reflux at 70-85℃ for 5-7 hours. After the reaction is completed, centrifuge, wash, and dry to obtain epoxy-functionalized boron nitride nanosheets. Step S2 is as follows: By weight, low-viscosity bisphenol A type epoxy resin, polypropylene glycol diglycidyl ether flexible diluent, silane coupling agent KH-560, and the aminated nano-silica and epoxy-functionalized boron nitride nanosheets prepared in step S1 are added to a planetary mixer. Under conditions of vacuum degree below -0.095MPa and temperature of 40-50℃, the mixture is stirred and premixed at a speed of 500-800rpm for 30 minutes. Then, 8-15 parts of dicyandiamide latent curing agent and 0.5-2 parts of 2-methylimidazole accelerator are added. Under the same vacuum and temperature conditions, the mixture is dispersed at a high speed of 1000-1500rpm for 60-120 minutes to ensure that the nanofillers are uniformly dispersed without agglomeration, thus obtaining the modified epoxy resin composition. Step S3 specifically involves placing the nanocrystalline magnetic core in an argon plasma cleaner and treating it for 3-10 minutes under conditions of 200-400W power, 20-40sccm argon flow rate, and 30-60Pa chamber pressure to clean and activate the surface of the magnetic core. Step S4 is as follows: Fix the nanocrystalline magnetic core treated in S3 into an impregnation fixture and place it into a vacuum pressure impregnation tank; preheat the modified epoxy resin composition prepared in S2 to 40-50℃ and inject it into the tank, ensuring that the magnetic core is completely submerged; first, evacuate to a pressure below 50Pa and maintain the pressure for 20-40 minutes to remove air bubbles from the resin and the pores of the magnetic core; then, introduce high-purity nitrogen to a pressure of 0.4-0.7MPa and maintain the pressure for 30-60 minutes to force the resin to penetrate; after releasing the pressure, remove the magnetic core, remove excess resin, and perform programmed temperature curing: first, pre-cur at 80-90℃ for 1-2 hours, then cure at 120-130℃ for 2-3 hours, and finally post-cur at 150-160℃ for 3-4 hours, then cool to room temperature with the furnace to complete the encapsulation.

[0009] Preferably, in S1, the average particle size of the nano-silica is 20-50 nm, the lateral dimension of the boron nitride nanosheets is 0.5-2 m, and the thickness is 3-10 nm; the concentration of the nanofiller in the first anhydrous ethanol solution is 5-10 mg / mL.

[0010] Preferably, in S2, the low-viscosity bisphenol A type epoxy resin has a viscosity of 3000-6000 mPas at 25°C; the epoxy value of polypropylene glycol diglycidyl ether is 0.45-0.60 eq / 100g; and the particle size D50 of the dicyandiamide latent curing agent is less than 10 μm.

[0011] Preferably, in step S2: the modified epoxy resin composition, by weight, comprises: 60-80 parts of low-viscosity bisphenol A epoxy resin, 10-20 parts of polypropylene glycol diglycidyl ether, 1-8 parts of aminated nano-silica, 2-10 parts of epoxy-functionalized boron nitride nanosheets, 8-15 parts of dicyandiamide, 0.5-2 parts of 2-methylimidazole, and 0.5-2 parts of silane coupling agent KH-560; wherein the aminated nano-silica and epoxy-functionalized boron nitride nanosheets are covalently linked to the epoxy resin matrix to form a three-dimensional reinforcing network, and the boron nitride nanosheets exhibit a directional arrangement tendency in the matrix, constituting a highly efficient thermally conductive pathway.

[0012] Preferably, in step S3, the surface of the nanocrystalline magnetic core is coated with a sealing layer with a thickness of 100-300 μm. The adhesion between the sealing layer and the magnetic core substrate reaches grade 0 of GB / T 9286-1998 standard, the dielectric constant at 1 MHz is not higher than 3.8, and the dielectric loss factor is not higher than 0.015.

[0013] Preferably, in step S2, the mixing temperature is below 55°C, and after high-speed stirring and dispersion, the viscosity of the composition at 25°C is 800-2000 mPas.

[0014] Preferably, the heating and curing process in S4 is carried out in a forced-air drying oven, and the heating rate is controlled at 1-2℃ / minute; after curing, the glass transition temperature of the encapsulation layer is not lower than 135℃, and the coefficient of thermal expansion is 40-60 ppm / ℃.

[0015] Preferably, in step S2, 0.1-0.5% of a defoamer and 0.2-1.0% of a leveling agent, accounting for 0.1-0.5% of the total mass of the epoxy resin, are added. The defoamer is a polysiloxane and the leveling agent is a polyacrylate.

[0016] The beneficial effects of this invention are as follows: it possesses excellent interfacial bonding and low internal stress; the aminated and epoxy-functionalized nanofillers are covalently linked to the epoxy resin network, greatly enhancing the interfacial bonding force. The synergistic effect of flexible segments and nanoparticles effectively reduces the curing shrinkage rate and coefficient of thermal expansion, significantly reducing the internal stress of the encapsulation layer and preventing cracking and delamination.

[0017] Enhanced thermal conductivity and heat resistance: Functionalized boron nitride nanosheets are well dispersed in the resin, forming effective thermal conductivity pathways and significantly improving the lateral thermal conductivity of the encapsulation layer. The dense organic-inorganic hybrid network increases the glass transition temperature and thermal decomposition temperature of the material.

[0018] High-frequency electrical insulation properties: Boron nitride nanosheets are excellent insulators with extremely low dielectric constant and loss. Their uniform dispersion in a low-polarity resin matrix effectively reduces the overall dielectric constant and dielectric loss of the composite material, meeting the requirements of high-frequency applications.

[0019] Process adaptability: Through filler surface modification and process control, the high filler carrying capacity and storage stability of the composite system at the applicable viscosity are ensured. The vacuum pressure impregnation process is mature and reliable, and suitable for large-scale production. Attached Figure Description Figure 1 This is a flowchart of the customized modification method for nanocrystalline magnetic core packaging materials proposed in this invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms installation, connection, linking, and setting should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] Example 1 This embodiment provides a method for modifying nanocrystalline magnetic core packaging materials, the steps of which are as follows: S1. Weigh 2g of nano-SiO2 with an average particle size of 30nm and 4g of BN nanosheets with a lateral dimension of approximately 1m, respectively, and add 200mL of anhydrous ethanol to each, and sonicate for 1 hour. Add 0.04g of KH-550 to the SiO2 dispersion and reflux at 70℃ for 5 hours. Add 0.12g of KH-560 to the BN dispersion and reflux at 75℃ for 6 hours. After the reaction, centrifuge, wash three times with ethanol, and vacuum dry at 60℃ for 12 hours to obtain aminated SiO2 and epoxy-functionalized BN.

[0023] S2. In a planetary mixer, add 70g of epoxy resin E-51 (viscosity 4500mPas), 15g of polypropylene glycol diglycidyl ether (EPG-207), 0.8g of KH-560, 2g of aminated SiO2, and 5g of epoxy-functionalized BN. Stir at 600rpm for 30 minutes at -0.098MPa and 45℃. Then add 10g of dicyandiamide (DICY, D50=5m) and 1.0g of 2-methylimidazole, and disperse at 1200rpm for 90 minutes under the same conditions to obtain modified epoxy resin composition A with a viscosity of approximately 1200mPas.

[0024] S3. After cleaning the nanocrystalline magnetic core with ethanol and drying it, place it in a plasma cleaner and treat it for 5 minutes at a power of 300W, an argon flow rate of 30sccm, and a pressure of 40Pa.

[0025] S4. Immerse the treated magnetic core in composition A preheated to 45°C and place it in a vacuum pressure vessel. Evacuate to 30 Pa and hold for 30 minutes; then introduce nitrogen gas to a pressure of 0.5 MPa and hold for 45 minutes. Remove the magnetic core and centrifuge to remove excess resin. Curing procedure: Increase the temperature to 85°C at 1.5°C / min and hold for 1.5 hours; then increase the temperature to 125°C and hold for 2.5 hours; finally, increase the temperature to 155°C and hold for 3.5 hours, then cool with the furnace.

[0026] Example 2 differs from Example 1 mainly in that the amount of inorganic nanofiller added in step S2 is less, specifically: the amount of aminated SiO2 added is 1g, and the amount of epoxy-functionalized BN added is 3g. The remaining steps and parameters are the same as in Example 1. A modified epoxy resin composition B with a viscosity of approximately 900 mPas was obtained.

[0027] Example 3 differs from Example 1 mainly in that the amount of inorganic nanofiller added in step S2 is greater, specifically: 4g of aminated SiO2 and 8g of epoxy-functionalized BN. Simultaneously, to maintain a suitable viscosity, the flexible diluent is increased to 18g. The high-speed dispersion time is extended to 120 minutes. The remaining steps and parameters are the same as in Example 1. A modified epoxy resin composition C with a viscosity of approximately 1800 mPas is obtained.

[0028] Example 4 differs from Example 1 mainly in the S4 curing procedure, which uses a higher post-curing temperature to achieve a higher crosslinking density: the curing procedure is: 90℃ / 2h + 130℃ / 3h + 160℃ / 4h. The remaining steps and parameters are the same as in Example 1.

[0029] Example 5: The main difference between this example and Example 1 is that in step S1, the BN nanosheets were not epoxy-functionalized; instead, they were amination treated with KH-550, similar to SiO2. That is, both fillers have amination surfaces. The remaining steps and parameters are the same as in Example 1. Modified epoxy resin composition D was obtained.

[0030] Comparative Example 1 used a pure epoxy resin system without any nanofillers for encapsulation. The formulation was: 70g E-51 epoxy resin, 15g EPG-207, 0.8g KH-560, 10g DICY, and 1.0g 2-methylimidazole. The mixing process, magnetic core treatment, and impregnation curing process were the same as in Example 1. Encapsulation material E was obtained.

[0031] Experimental Example: Performance Testing and Comparison The packaging materials prepared in Examples 1-5 and Comparative Example 1 were cast into standard test strips, and the performance of the packaged magnetic cores was tested.

[0032] 1. Performance testing of encapsulation materials: Thermal conductivity: The in-direction thermal conductivity at room temperature was tested using a laser scintillation thermal conductivity analyzer.

[0033] Glass transition temperature: Tg was measured using a dynamic thermomechanical analyzer at a heating rate of 3℃ / min.

[0034] Coefficient of thermal expansion: The average CTE was measured using a thermomechanical analyzer in the temperature range from room temperature to 50°C below Tg.

[0035] Dielectric properties: The dielectric constant and dielectric loss factor were tested at a frequency of 1 MHz using an impedance analyzer.

[0036] Tensile strength and elongation at break: tested according to ASTM D638 standard.

[0037] 2. Performance testing of encapsulated magnetic core: Adhesion: The cross-cut test shall be conducted in accordance with GB / T 9286-1998, and the evaluation shall be graded from 0 to 5.

[0038] High-temperature storage test: The magnetic core was placed in a 125°C oven for 1000 hours, and the rate of change of inductance before and after was tested (test conditions: 1kHz, 0.1V).

[0039] Double 85 damp heat test: Place the magnetic core in an 85℃ / 85%RH constant temperature and humidity chamber for 1000 hours and test the change in insulation resistance (DC 500V) before and after.

[0040] Temperature cycling test: -55℃ (30min) → 125℃ (30min), 200 cycles, observe whether the appearance cracks, and test the rate of change of inductance.

[0041] The test results are summarized in the table below: Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Thermal conductivity (W / mK) 0.68 0.52 0.81 0.70 0.60 0.22 Tg (°C) 142 138 145 148 140 125 CTE (ppm / ℃) 48 55 42 47 51 72 Dielectric constant @ 1MHz 3.65 3.72 3.60 3.63 3.75 4.10 Dielectric loss @ 1MHz 0.012 0.014 0.011 0.012 0.016 0.025 Tensile strength (MPa) 85 78 89 87 80 65 Elongation at break (%) 4.5 5.2 3.8 4.2 4.8 6.0 Adhesion (Grade) 0 0 0 0 0 1 Inductance change at 125℃ / 1000h -2.1 -2.5 -1.8 -1.9 -2.8 -5.5 The insulation resistance of the double 85 / 1000h decreased Half an order of magnitude Half an order of magnitude Half an order of magnitude Half an order of magnitude 1 order of magnitude 2 orders of magnitude Appearance after temperature cycling intact intact intact intact Slight cracks at the corners Local cracking Results Analysis: 1. The performance of all embodiments is significantly better than that of Comparative Example 1, which proves the effectiveness of the modification method of the present invention.

[0042] 2. Example 1 (optimized formula) has the best overall performance, achieving a good balance between thermal conductivity, heat resistance, low expansion, low dielectric loss and mechanical properties.

[0043] 3. Example 2 (low filler content) showed a slight decrease in thermal conductivity and mechanical strength, and a slightly higher CTE. Example 3 (high filler content) exhibited the best thermal conductivity and heat resistance, and the lowest CTE, but its toughness (elongation at break) decreased, and its process viscosity increased.

[0044] 4. Example 4 (high curing temperature) achieved a higher Tg, but other properties were similar to those of Example 1, indicating that the original curing procedure was sufficient.

[0045] 5. The dielectric loss, insulation resistance retention rate after damp heat, and appearance after temperature cycling of Example 5 (same modification of BN) are slightly worse than those of Example 1, indicating that differentiated epoxy functionalization of BN can optimize its interface and distribution more effectively than simple amylation, thereby improving overall reliability.

[0046] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for tailored modification of nanocrystalline magnetic core encapsulation materials, characterized in that, Includes the following steps: S1: Surface functionalization modification of nano-silica and boron nitride nanosheets by grafting amino and epoxy groups, respectively; S2: The modified inorganic nanofiller is blended and dispersed with low-viscosity bisphenol A type epoxy resin, flexible epoxy resin diluent, latent curing agent and coupling agent under high shear force to form a uniform and stable modified epoxy resin composition. S3: Plasma cleaning and activation treatment of nanocrystalline magnetic core; S4: The modified epoxy resin composition is encapsulated on the surface of the magnetic core using a vacuum pressure impregnation process, and then cured by programmed temperature rise.

2. The method for tailored modification of nanocrystalline magnetic core encapsulation material according to claim 1, wherein, In the modification method: Step S1 is as follows: Weigh nano-silica and boron nitride nanosheets separately, and ultrasonically disperse them in a first anhydrous ethanol solution; add 1-3% by mass of -aminopropyltriethoxysilane to the nano-silica dispersion, and reflux at 60-80℃ for 4-6 hours. After the reaction is completed, centrifuge, wash, and dry to obtain amino-modified nano-silica; add 2-4% by mass of -(2,3-epoxypropoxy)propyltrimethoxysilane to the boron nitride nanosheet dispersion, and reflux at 70-85℃ for 5-7 hours. After the reaction is completed, centrifuge, wash, and dry to obtain epoxy-functionalized boron nitride nanosheets. Step S2 is as follows: By weight, low-viscosity bisphenol A type epoxy resin, polypropylene glycol diglycidyl ether flexible diluent, silane coupling agent KH-560, and the aminated nano-silica and epoxy-functionalized boron nitride nanosheets prepared in step S1 are added to a planetary mixer. Under conditions of vacuum degree below -0.095MPa and temperature of 40-50℃, the mixture is stirred and premixed at a speed of 500-800rpm for 30 minutes. Then, 8-15 parts of dicyandiamide latent curing agent and 0.5-2 parts of 2-methylimidazole accelerator are added. Under the same vacuum and temperature conditions, the mixture is dispersed at a high speed of 1000-1500rpm for 60-120 minutes to ensure that the nanofillers are uniformly dispersed without agglomeration, thus obtaining the modified epoxy resin composition. Step S3 specifically involves placing the nanocrystalline magnetic core in an argon plasma cleaner and treating it for 3-10 minutes under conditions of 200-400W power, 20-40sccm argon flow rate, and 30-60Pa chamber pressure to clean and activate the surface of the magnetic core. Step S4 is as follows: Fix the nanocrystalline magnetic core treated in S3 into an impregnation fixture and place it into a vacuum pressure impregnation tank; preheat the modified epoxy resin composition prepared in S2 to 40-50℃ and inject it into the tank, ensuring that the magnetic core is completely submerged; first, evacuate to a pressure below 50Pa and maintain the pressure for 20-40 minutes to remove air bubbles from the resin and the pores of the magnetic core; then, introduce high-purity nitrogen to a pressure of 0.4-0.7MPa and maintain the pressure for 30-60 minutes to force the resin to penetrate; after releasing the pressure, remove the magnetic core, remove excess resin, and perform programmed temperature curing: first, pre-cur at 80-90℃ for 1-2 hours, then cure at 120-130℃ for 2-3 hours, and finally post-cur at 150-160℃ for 3-4 hours, then cool to room temperature with the furnace to complete the encapsulation.

3. The method for tailored modification of nanocrystalline magnetic core encapsulation materials according to claim 2, wherein, In S1, the average particle size of the nano-silica is 20-50 nm, the lateral dimension of the boron nitride nanosheets is 0.5-2 m, and the thickness is 3-10 nm; the concentration of the nanofiller in the first anhydrous ethanol solution is 5-10 mg / mL.

4. The method for tailored modification of nanocrystalline magnetic core encapsulation material according to claim 2, wherein, In S2, the viscosity of the low-viscosity bisphenol A type epoxy resin at 25°C is 3000-6000 mPas; the epoxy value of polypropylene glycol diglycidyl ether is 0.45-0.60 eq / 100g; and the particle size D50 of the dicyandiamide latent curing agent is less than 10 μm.

5. The method for tailored modification of nanocrystalline magnetic core encapsulation material according to claim 2, wherein, In step S2: the modified epoxy resin composition, by weight, comprises: 60-80 parts of low-viscosity bisphenol A epoxy resin, 10-20 parts of polypropylene glycol diglycidyl ether, 1-8 parts of aminated nano-silica, 2-10 parts of epoxy-functionalized boron nitride nanosheets, 8-15 parts of dicyandiamide, 0.5-2 parts of 2-methylimidazole, and 0.5-2 parts of silane coupling agent KH-560; wherein the aminated nano-silica and epoxy-functionalized boron nitride nanosheets are covalently linked to the epoxy resin matrix to form a three-dimensional reinforcing network, and the boron nitride nanosheets exhibit a directional arrangement tendency in the matrix, constituting a highly efficient thermal conduction pathway.

6. The customized modification method for nanocrystalline magnetic core packaging materials according to claim 2, characterized in that, In step S3, the surface of the nanocrystalline magnetic core is coated with a sealing layer with a thickness of 100-300 μm. The adhesion between the sealing layer and the magnetic core substrate reaches grade 0 of GB / T 9286-1998 standard. The dielectric constant at a frequency of 1 MHz is not higher than 3.8, and the dielectric loss factor is not higher than 0.

015.

7. The method for tailored modification of nanocrystalline magnetic core encapsulation material of claim 2, wherein, In step S2, the mixing temperature is below 55°C, and after high-speed stirring and dispersion, the viscosity of the composition at 25°C is 800-2000 mPas.

8. The method for tailored modification of nanocrystalline magnetic core encapsulation material of claim 2, wherein, The heating and curing process in S4 is carried out in a forced-air drying oven, with the heating rate controlled at 1-2℃ / minute; after curing, the glass transition temperature of the encapsulation layer is not lower than 135℃, and the coefficient of thermal expansion is 40-60 ppm / ℃.

9. The method for tailored modification of nanocrystalline magnetic core encapsulation material of claim 2, wherein, In step S2, 0.1-0.5% of a defoamer and 0.2-1.0% of a leveling agent, accounting for 0.1-0.5% of the total mass of the epoxy resin, are added. The defoamer is a polysiloxane and the leveling agent is a polyacrylate.

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