A method for preparing an antifoaming composition

Abstract

This invention relates to the preparation of an antifoaming composition, which is made from a carrier, inorganic hydrophobic particles, organic solid wax, polyether silicone copolymer, and emulsifier. Through the synergistic effect of the specially structured polyether silicone copolymer and organic solid wax, the foam control capability during the production and application of elastic coatings is significantly improved, while its stability and foam control performance are unaffected by temperature.

Description

Technical Field

[0001] This invention relates to a method for preparing an antifoaming composition that can eliminate bubbles during the production and application of elastic coatings, and belongs to the field of fine chemical technology. Technical Background

[0002] Elastic coatings are thick-film interior and exterior wall coatings composed of fine fillers, elastic acrylic binders, and other additives. With a glass transition temperature between -28°C and 22°C, the coating film exhibits strong elasticity at room temperature, with an elongation rate reaching 370%. It boasts excellent flexibility, impact resistance, waterproofing, breathability, and sound absorption. Furthermore, it is easy to apply and allows for diverse application techniques to create striking and varied decorative effects. Offering a range of natural decorative qualities, it aligns with modern architectural characteristics and development trends. It is widely used on smooth, rough surfaces such as cement mortar, gravel, gypsum board, and plywood in large buildings including hotels, guesthouses, office buildings, entertainment venues, residences, schools, and hospitals.

[0003] Foaming issues exist during the production and application of elastic coatings, affecting product quality. Because elastic coatings form a protective film of a certain thickness, internal air bubbles are more difficult to remove than in ordinary coatings. Therefore, eliminating these bubbles is crucial for the quality of elastic coatings. Generally, defoamers are used to solve this problem.

[0004] Defoamers are classified according to their active ingredients, mainly into silicone defoamers and non-silicone defoamers. Silicone defoamers are primarily composed of polysiloxanes, silica, emulsifiers, and water. Their advantage is rapid defoaming, but their disadvantage is poor compatibility with foaming systems, easily leading to defects such as silica spots and pinholes when used in coatings. Non-silicone defoamers are generally composed of mineral oils, fatty alcohols, fatty acid esters, metal soaps, fatty acid amides, and polyethers. Their defoaming function is not as fast as silicone defoamers, but they have better compatibility and higher safety. In general, due to the wide variety of application systems, the choice of defoamer varies. Comparatively, mineral oil-based defoamers are more favored for elastic coating systems.

[0005] Among existing patent technologies, there are quite a few mineral oil-based defoamers. For example, US3076768 describes a defoamer composed of hydrophobic silica, hydrocarbons, and dispersants; US4094812 describes a method for preparing a mineral oil-based defoamer containing an α-hydroxyamine derivative; US3652452 describes a defoamer composed of hydrocarbons and amides, requiring rapid cooling during preparation to stabilize the amide's crystal lattice; CN101903074B describes a mineral oil defoamer composed of hydrocarbons, dispersants, and silica dispersion; and CN101445760 describes a defoamer composed of ethylene bis-stearamide, hydrocarbons, and hydrophilic silica. Defoamers containing carbon black are described in CN101003644, which describes a defoamer for peritoneal adhesives containing hydrocarbons and fatty acid amides; CN2007100251825.1 describes a defoamer containing hydrocarbons and aluminum stearate; CN201010550336.7 describes a defoamer composed of hydrocarbons, waxes, silica, emulsifiers, and oleic acid, using a colloid mill cyclic grinding process; CN102120107B and CN201010550282.4 describe the preparation of mineral oil-based defoamers using high-speed grinding. These existing defoamers all rely on hydrocarbons, hydrophobic particles, and emulsifiers. However, extensive experiments and applications have shown that these technologies cannot solve the foaming problem in elastic coatings.

[0006] The inventors of this patent have conducted extensive experiments and research on this issue and discovered that by adding a combination of waxes with different melting points and special polyether-modified polysiloxanes to a combination of carrier material, inorganic hydrophobic particles and emulsifier, the foam control capability during the production and application of elastic coatings can be significantly improved. At the same time, the stability and foam control performance are not affected by temperature. Summary of the Invention

[0007] This invention provides an antifoaming composition that is effective in eliminating bubbles in elastic coating systems, and whose stability and foam control performance are not affected by temperature.

[0008] The defoaming composition comprises a carrier, inorganic hydrophobic particles, organic solid wax, polyether silicone copolymer, and emulsifier.

[0009] A. Carrier

[0010] The carrier is a tool that carries hydrophobic particles to penetrate the surface of bubbles in the system. It is a liquid hydrocarbon composed of carbon and hydrogen atoms, or a vegetable oil and its derivatives composed of carbon, hydrogen and oxygen atoms, or a polyether.

[0011] The hydrocarbons mentioned include base oil, white oil, alkylbenzene, naphthenic oil, liquid wax, diesel, engine oil, and kerosene.

[0012] The vegetable oils mentioned include soybean oil, rapeseed oil, olive oil, sunflower seed oil, peanut oil, cottonseed oil, flaxseed oil, castor oil, and fatty acid methyl esters derived from them.

[0013] The polyether is an addition product of propylene glycol, glycerol and propylene oxide, with a molecular weight of 2000-5000.

[0014] These carriers are liquids at room temperature and can be used alone or in combination.

[0015] The amount of the carrier used is 50-85% of the total mass of the defoaming composition.

[0016] B. Inorganic hydrophobic particles

[0017] The inorganic hydrophobic particles are one or more of silicon dioxide (commonly known as "white carbon black"), aluminum oxide, zinc oxide, or magnesium oxide. This invention preferably uses hydrophobic white carbon black with a specific surface area of ​​80–500 m². 2 / g.

[0018] Generally, hydrophobic silica is obtained by heating and stirring hydrophilic silica and a hydrophobic treatment agent in a reaction vessel. Materials that make the silica surface hydrophobic include low-viscosity trimethylsiloxy-terminated polydimethylsiloxane, low-viscosity hydroxyl-terminated polydimethylsiloxane, hexamethyldisilazane, hexamethyldisilazane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, long-chain fatty alcohols or fatty acids with more than twelve carbon atoms, octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, and hexamethylcyclotrisiloxane. The preferred treatment agent in this invention is a long-chain fatty alcohol or fatty acid with more than twelve carbon atoms.

[0019] The process of hydrophobic silica generally involves adding an appropriate catalyst at a temperature above 80°C and maintaining the temperature for a period of time. The type and amount of hydrophobic agent directly determine the degree of hydrophobicity of the resulting hydrophobic silica.

[0020] Based on the preparation process of inorganic hydrophobic silica, it can be divided into fumed hydrophobic silica and precipitated hydrophobic silica. When preparing the defoaming composition, the hydrophobic silica prepared by the different methods are mixed in any proportion, and both methods must be used simultaneously.

[0021] The inorganic hydrophobic particles constitute 2-10% of the total mass of the defoaming composition.

[0022] C. Organic solid wax

[0023] The organic solid waxes described herein are waxes composed of hydrocarbons or hydrocarbons with melting points of 60–150°C. These include one or more mixtures of paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, polyamide wax, and oxidized polyethylene wax, with particle sizes less than 50 μm. The organic solid waxes of this invention are mixtures with melting points below 100°C and above 100°C, with a difference in melting point range greater than 40°C. The mass ratio of high-melting-point wax to low-melting-point wax is not limited.

[0024] The organic solid wax constitutes 2-8% of the total mass of the defoaming composition.

[0025] D. Polyether silicone copolymer

[0026] The general structural formula of the polyether silicone copolymer is as follows:

[0027]

[0028] In the above formula, a and b are the degrees of polymerization of ethylene oxide (EO) and propylene oxide (PO) repeating units, and c is the degree of polymerization of organosilicon repeating units; a is 0 or 1 to 10, b is 30 to 60, and c is 2 to 6.

[0029] The synthesis method of polyether organosilicon copolymer is as follows: after adding glycerol polyether to a container and starting the stirrer, add hydroxyl-terminated polysiloxane according to the molar ratio, and then add potassium hydroxide catalyst at 0.5% of the total mass of the reactants. The reaction is carried out under negative pressure at 100-200℃ and -0.01 to -0.08 MPa for 2-10 hours to obtain polyether organosilicon copolymer.

[0030] The amount of the polyether silicone copolymer used is 5-30% of the total mass of the defoaming composition.

[0031] E. Emulsifiers

[0032] The emulsifiers mentioned are mainly used to emulsify and disperse the carrier oil in the application system. They mainly refer to nonionic surfactants, including fatty primary alcohol polyoxyethylene ethers, fatty secondary alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, oleic acid polyoxyethylene ethers, oleyl alcohol polyoxyethylene ethers, stearic acid polyoxyethylene ethers, and castor oil polyoxyethylene ethers.

[0033] The amount of emulsifier used is 2-10% of the total mass of the defoaming composition.

[0034] The method for preparing the defoaming composition of the present invention is as follows:

[0035] Organic solid wax with a melting point below 100℃, gaseous inorganic hydrophobic particles and polyether silicone copolymer are added to a container, along with zirconium beads with a diameter of 0.5 mm. The mixture is ground for 0.5 to 3 hours while maintaining a temperature below 60℃, and then cooled to room temperature to obtain a "wax slurry".

[0036] Add the carrier, organic solid wax with a melting point above 100℃, precipitated inorganic hydrophobic particles and emulsifier to another container, start stirring, raise the temperature to 120-180℃, disperse at a speed of 2000-6000 rpm for 1-3 hours, and then quickly cool down to 80-90℃ to obtain the "dispersion".

[0037] Add "wax paste" to a container, then slowly add "dispersion" at a temperature of 80-90°C, control the temperature of the resulting mixture at 40-50°C, and finally pass it through a high-pressure homogenizer at a pressure of 0.1-2 MPa to obtain the defoaming composition. Detailed Implementation

[0038] Selection of polyether silicone copolymer D:

[0039] The general structural formula of polyether silicone copolymer D is as follows:

[0040]

[0041] The values ​​of the subscripts a, b, and c in the embodiments are shown in Table 1:

[0042] Table 1 Examples of polyether silicone copolymers D

[0043] Polyether silicone copolymer D a b c D1 0 55 4 D2 1 30 2 D3 10 45 6 D4 0 20 3

[0044] Example 1

[0045] Add 1 part of solid wax with a particle size of 45μm and a melting point of 60℃, and 1 part of solid wax with a specific surface area of ​​200m² to the container. 2 / g of lauryl alcohol hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D1 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 50℃ for 1h and then cooled to room temperature to obtain "wax paste".

[0046] In another container, add 71.3 parts base oil, 1.5 parts oxidized polyethylene wax with a particle size of 30 μm and a melting point of 110 °C, and 1.2 parts of a specific surface area of ​​100 m². 2 After adding / g of octadecyl alcohol hydrophobically treated precipitated silica and 4 parts of emulsifier TMIN 6, stirring was started, the temperature was raised to 130℃, and the mixture was dispersed at 2000rpm for 3h. Then, the temperature was rapidly lowered to 80℃ to obtain the "dispersion".

[0047] Add "wax paste" to a container, then slowly add "oil dispersion" at 80°C, control the temperature of the resulting mixture at 42°C, and finally pass it through a high-pressure homogenizer at 1 MPa to obtain defoaming composition S1.

[0048] Example 2

[0049] Add 0.5 parts of microcrystalline wax with a particle size of 35 μm and a melting point of 75℃, and 0.5 parts of a specific surface area of ​​380 m² to the container. 2 / g of eicosyl hydrophobically treated fumed silica and 5 parts of polyether silicone copolymer D3 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 58℃ for 0.5h and then cooled to room temperature to obtain "wax paste".

[0050] In another container, add 84 parts of glycerol polyether (all-propylene oxide, molecular weight 5000), 3.5 parts of polypropylene wax with a particle size of 48 μm and a melting point of 150 °C, and 4.5 parts of a specific surface area of ​​80 m². 2 After adding / g of hexadecyl alcohol hydrophobically treated precipitated silica and 2 parts of emulsifier branched isomeric tridecyl alcohol polyoxyethylene ether EX1305, stirring was started, the temperature was raised to 175℃, and the mixture was dispersed at 6000rpm for 1h. Then, the temperature was rapidly lowered to 90℃ to obtain the "dispersion".

[0051] Add "wax paste" to a container, then slowly add "oil dispersion" at 90°C, control the temperature of the resulting mixture at 50°C, and finally pass it through a high-pressure homogenizer at 2MPa to obtain defoaming composition S2.

[0052] Example 3

[0053] Add 2 parts of polyethylene wax with a particle size of 30μm and a melting point of 85℃, and 2 parts of a specific surface area of ​​500m² to the container. 2 / g of hydrophobically treated fumed silica and 17 parts of polyether silicone copolymer D4 were mixed with zirconium beads with a diameter of 0.5mm. The mixture was ground at 46℃ for 3 hours and then cooled to room temperature to obtain "wax paste".

[0054] In another container, add 60 parts soybean oil, 6 parts oxidized polyethylene wax with a particle size of 30 μm and a melting point of 135 °C, and 8 parts of a specific surface area of ​​170 m². 2 After adding / g of octadecyl alcohol hydrophobically treated precipitated silica and 5 parts of emulsifier oleyl alcohol polyoxyethylene ether (6), stirring was started, the temperature was raised to 155°C, and the mixture was dispersed at 3000 rpm for 2 hours. Then, the temperature was rapidly lowered to 83°C to obtain the "dispersion".

[0055] Add "wax paste" to a container, then slowly add "oil dispersion" at a temperature of 83°C, control the temperature of the resulting mixture at 42°C, and finally pass it through a high-pressure homogenizer at a pressure of 0.1 MPa to obtain defoaming composition S3.

[0056] Example 4

[0057] Add 2 parts of polyamide wax with a particle size of 40 μm and a melting point of 60 °C, and 1 part of polyamide wax with a specific surface area of ​​280 m² to the container.2 / g of oleyl alcohol hydrophobically treated fumed silica and 30 parts of polyether organosilicon copolymer D2 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 35℃ for 1.5h and then cooled to room temperature to obtain "wax paste".

[0058] In another container, add 54 parts methyl oleate, 2 parts oxidized polyethylene wax with a particle size of 30 μm and a melting point of 110 °C, and 2 parts with a specific surface area of ​​110 m². 2 / g of hydrophobically treated precipitated silica and 9 parts of emulsifier oleyl alcohol polyoxyethylene ether (10) were added, and stirring was started. The temperature was raised to 125°C and dispersed at 2500 rpm for 1.8h. Then the temperature was quickly lowered to 83°C to obtain the "dispersion".

[0059] Add "wax paste" to a container, then slowly add "oil dispersion" at 83°C, control the temperature of the resulting mixture at 46°C, and finally pass it through a high-pressure homogenizer at 0.5 MPa to obtain defoaming composition S4.

[0060] Example 5

[0061] Add 1.5 parts of microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 2 parts of a specific surface area of ​​220 m² to the container. 2 / g of lauric acid hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D4 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax paste".

[0062] In another container, add 65 parts propylene glycol polyether (molecular weight 4200, all-propylene oxide), 2 parts oxidized polyethylene wax with a particle size of 40 μm and a melting point of 130 °C, and 3.5 parts with a specific surface area of ​​130 m². 2 After adding / g of palmitic acid hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and the mixture was dispersed at 3000 rpm for 2.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0063] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5.

[0064] Comparative Example 1 (without special polyether silicone copolymer)

[0065] Add 1.5 parts of microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 2 parts of a specific surface area of ​​220 m² to the container. 2 / g of lauric acid hydrophobically treated fumed silica and 20 parts of propylene glycol polyether (molecular weight 4200, all-propylene oxide) were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax slurry".

[0066] In another container, add 65 parts propylene glycol polyether (molecular weight 4200, all-propylene oxide), 2 parts oxidized polyethylene wax with a particle size of 40 μm and a melting point of 130 °C, and 3.5 parts with a specific surface area of ​​130 m². 2 After adding / g of palmitic acid hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and the mixture was dispersed at 3000 rpm for 2.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0067] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5-1.

[0068] Comparative Example 2 (without wax)

[0069] Add 3.5 parts of a specific surface area of ​​220m² to the container. 2 / g of lauric acid hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D4 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax paste".

[0070] Add 65 parts of propylene glycol polyether (molecular weight 4200, all-propylene oxide) and 5.5 parts of a specific surface area of ​​130 m² to another container. 2 After adding / g of palmitic acid hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and the mixture was dispersed at 3000 rpm for 2.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0071] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5-2.

[0072] Comparative Example 3 (using different waxes and polyether silicone copolymers)

[0073] Add 85 parts of propylene glycol polyether (molecular weight 4200, all-propylene oxide) and 2.6 parts of a specific surface area of ​​220 m² to a container. 2 / g of lauric acid hydrophobically treated fumed silica, 4.6 parts with a specific surface area of ​​130m²2 After adding / g of palmitic acid hydrophobically treated precipitated silica and 7.8 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and dispersed at 3000 rpm for 2.5h. Then, the temperature was rapidly lowered to 86°C, and then slowly lowered to 40°C. Finally, the mixture was homogenized by a high-pressure homogenizer with a pressure of 1.2MPa to obtain the defoaming composition S5-3.

[0074] Comparative Example 4 (Silica treated with other hydrophobic agents)

[0075] Add 1.5 parts of microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 2 parts of a specific surface area of ​​220 m² to the container. 2 / g of hexamethyldisilazane hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D4 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax paste".

[0076] In another container, add 65 parts propylene glycol polyether (molecular weight 4200, all-propylene oxide), 2 parts oxidized polyethylene wax with a particle size of 40 μm and a melting point of 130 °C, and 3.5 parts with a specific surface area of ​​130 m². 2 After adding / g of chlorosilane hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145℃, and the mixture was dispersed at 3000rpm for 2.5h. Then, the temperature was rapidly lowered to 86℃ to obtain the "dispersion".

[0077] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5-4.

[0078] Comparative Example 5 (using the same type of wax)

[0079] Add 1.5 parts of microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 2 parts of a specific surface area of ​​220 m² to the container. 2 / g of lauric acid hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D4 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax paste".

[0080] In another container, add 65 parts propylene glycol polyether (molecular weight 4200, all-propylene oxide), 2 parts microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 3.5 parts with a specific surface area of ​​130 m². 2After adding / g of palmitic acid hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and the mixture was dispersed at 3000 rpm for 2.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0081] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5-5.

[0082] Comparative Example 6 (the difference in melting point between different waxes is less than 40 degrees Celsius)

[0083] Add 1.5 parts of microcrystalline wax with a particle size of 30 μm and a melting point of 65 °C, and 2 parts of a specific surface area of ​​220 m² to the container. 2 / g of lauric acid hydrophobically treated fumed silica and 20 parts of polyether organosilicon copolymer D4 were added with zirconium beads with a diameter of 0.5mm. The mixture was ground at 44℃ for 2.8h and then cooled to room temperature to obtain "wax paste".

[0084] In another container, add 65 parts propylene glycol polyether (molecular weight 4200, all-propylene oxide), 2 parts oxidized polyethylene wax with a particle size of 40 μm and a melting point of 95 °C, and 3.5 parts with a specific surface area of ​​130 m². 2 After adding / g of palmitic acid hydrophobically treated precipitated silica and 6 parts of emulsifier decanol polyoxyethylene ether (15), stirring was started, the temperature was raised to 145°C, and the mixture was dispersed at 3000 rpm for 2.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0085] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 40°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S5-6.

[0086] Comparative Example 7

[0087] Prepared according to Example 1 of CN201010550336.7, and named S5-7.

[0088] Example 6

[0089] Add 3 parts of microcrystalline wax with a particle size of 10 μm and a melting point of 80℃, and 3 parts of a specific surface area of ​​380 m² to the container. 2 / g of dexamethasone hydrophobically treated fumed silica, 24 parts of polyether silicone copolymer D2 and polyether silicone copolymer D4, and 0.5mm diameter zirconium beads were added. The mixture was ground at 55℃ for 2 hours and then cooled to room temperature to obtain "wax paste".

[0090] In another container, add 10 parts methyl oleate, 52 parts white oil, 1.5 parts polyamide wax with a particle size of 25 μm and a melting point of 130 °C, and 0.5 parts polyamide wax with a specific surface area of ​​190 m². 2 After adding / g of tetradecyl alcohol hydrophobically treated precipitated silica and 6 parts of emulsifier castor oil polyoxyethylene ether (12), stirring was started, the temperature was raised to 165°C, and the mixture was dispersed at 1500 rpm for 1.5 h. Then, the temperature was rapidly lowered to 86°C to obtain the "dispersion".

[0091] Add "wax paste" to a container, then slowly add "oil dispersion" at 86°C, control the temperature of the resulting mixture at 48°C, and finally pass it through a high-pressure homogenizer at 1.2 MPa to obtain defoaming composition S6.

[0092] Example 7

[0093] Add 1 part of microcrystalline wax with a particle size of 15 μm and a melting point of 75 °C and 0.2 parts of a specific surface area of ​​380 m² to the container. 2 / g of tridecanol-treated hydrophobic fumed silica, 0.3 parts of which have a specific surface area of ​​200m² 2 / g of stearic acid hydrophobically treated fumed silica, 10 parts of polyether organosilicon copolymer D1 and 5 parts of polyether organosilicon copolymer D3, and 0.5mm diameter zirconium beads were added. The mixture was ground at 45℃ for 1.5h and then cooled to room temperature to obtain "wax paste".

[0094] In another container, add 10 parts naphthenic oil, 10 parts white oil, 50 parts propylene glycol polyether (molecular weight 3000, all-propylene oxide), 4 parts polyethylene wax with a diameter of 20 μm and a melting point of 120 °C, and 4.5 parts of a specific surface area of ​​190 m². 2 / g of tetradecyl alcohol hydrophobically treated precipitated silica and 5 parts of emulsifier oleic acid polyoxyethylene ether (10) were added, and stirring was started. The temperature was raised to 145°C and dispersed at 3500 rpm for 2 hours. Then the temperature was quickly lowered to 82°C to obtain the "dispersion".

[0095] Add "wax paste" to a container, then slowly add "oil dispersion" at 82°C, control the temperature of the resulting mixture at 44°C, and finally pass it through a high-pressure homogenizer at 0.8 MPa to obtain defoaming composition S7.

[0096] Performance testing of the defoaming composition:

[0097] (1) Stability test

[0098] The samples from Examples 1-7 and Comparative Examples 1-7 were sealed and stored at 5°C, 25°C and 40°C for one month, and the appearance of the samples was observed. The results are shown in Table 2.

[0099] (2) Defoaming performance:

[0100] Using elastic acrylic paint as the test medium, 250g of paint and 0.5g of test sample were weighed and added to a 500ml beaker. The mixture was dispersed at 3000rpm for 15min using a disperser, and the density of the dispersed elastic acrylic paint was measured. A higher density value indicates better defoaming performance, and vice versa; the results are shown in Table 2.

[0101] To illustrate the temperature adaptability of the defoaming composition, the defoaming performance of the elastic acrylic coating at 10°C and 30°C was tested.

[0102] Table 2. Stability comparison of different samples

[0103]

[0104] By analyzing the data in Table 2 above, we can draw the following conclusions:

[0105] (1) Samples S1-S6 prepared by the method of the invention patent have good foam control performance in elastic acrylic coatings. The performance is not affected by temperature and the samples themselves have good stability.

[0106] (2) Comparing the experimental data of S5 and S5-1 to S5-3, it can be seen that when wax or polyether silicone copolymer is used alone, the foam control performance of the obtained products is relatively poor.

[0107] (3) Comparison of the experimental data of S5 and S5-4 shows that different hydrophobic treatment agents have a significant impact on the stability of the samples, but not a significant impact on the foam control performance. This indicates that the surface modification groups of silica and the carrier have a certain degree of similarity and compatibility, which increases the stability of the samples.

[0108] (4) Comparing the experimental data of S5 and S5-5~S5-6, it can be seen that when using the same type of wax, the sample effect is greatly affected by temperature and the stability is poor; when the sample uses wax with a melting point difference of no more than 40℃, the storage stability is poor and the performance is affected by temperature to a certain extent.

[0109] (5) Samples prepared by existing technology and commercially available samples were also tested in elastic acrylic coatings, and their performance and stability were not ideal.

[0110] Therefore, the defoaming composition prepared by this patented method has the characteristics of good stability, excellent foam control performance, and performance unaffected by temperature.

Claims

1. An antifoaming composition, characterized in that, It is prepared using a carrier, inorganic hydrophobic particles, organic solid wax, polyether silicone copolymer, and emulsifier. A. Carrier: The carrier is a liquid hydrocarbon substance composed of carbon and hydrogen atoms, or a vegetable oil and its derivatives composed of carbon, hydrogen and oxygen atoms, or a polyether; these carriers are liquid at room temperature and can be used alone or in combination; the total amount of the carrier is 50-85% of the total mass of the defoaming composition; B. Inorganic hydrophobic particles, wherein the inorganic hydrophobic particles are hydrophobic silica with a specific surface area of ​​80–500 m². 2 / g, the hydrophobic treatment agent is a long-chain fatty alcohol or fatty acid with more than twelve carbon atoms; the inorganic hydrophobic particles are 2 to 10% of the total mass of the defoaming composition; C. Organic solid wax, wherein the organic solid wax is a mixture of one or more of paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, polyamide wax and oxidized polyethylene wax with a melting point of 60-150℃; the organic solid wax is 2-8% of the total mass of the defoaming composition. D. Polyether-organic silicone copolymer, wherein the general structural formula of the polyether-organic silicone copolymer is as follows: In the above formula, a and b are the degrees of polymerization of ethylene oxide (EO) and propylene oxide (PO) repeating units, and c is the degree of polymerization of organosilicon repeating units; a is 0 or 1 to 10, b is 30 to 60, and c is 2 to 6. The amount of the polyether silicone copolymer used is 5-30% of the total mass of the defoaming composition; E. Emulsifier, wherein the emulsifier is selected from fatty primary alcohol polyoxyethylene ether, fatty secondary alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, oleic acid polyoxyethylene ether, oleyl alcohol polyoxyethylene ether, stearic acid polyoxyethylene ether, castor oil polyoxyethylene ether. The amount of emulsifier used is 2-10% of the total mass of the defoaming composition; The defoaming composition is prepared as follows: Organic solid wax with a melting point below 100℃, gaseous inorganic hydrophobic particles and polyether silicone copolymer are added to a container, along with zirconium beads with a diameter of 0.5 mm. The mixture is ground for 0.5 to 3 hours while maintaining a temperature below 60℃, and then cooled to room temperature to obtain "wax slurry". Add the carrier, organic solid wax with a melting point above 100℃, precipitated inorganic hydrophobic particles and emulsifier to another container, start stirring, raise the temperature to 120-180℃, disperse at a speed of 2000-6000 rpm for 1-3 hours, and then quickly cool down to 80-90℃ to obtain the "dispersion". Add "wax paste" to a container, then slowly add "dispersion" at a temperature of 80-90°C, control the temperature of the resulting mixture at 40-50°C, and finally pass it through a high-pressure homogenizer at a pressure of 0.1-2 MPa to obtain the defoaming composition.

2. The defoaming composition according to claim 1, characterized in that, The hydrocarbons in the carrier are selected from base oils, white oils, alkylbenzenes, naphthenic oils, liquid waxes, diesel oils, engine oils, and kerosene; the vegetable oils in the carrier are selected from soybean oil, rapeseed oil, olive oil, sunflower seed oil, peanut oil, cottonseed oil, linseed oil, castor oil, and fatty acid methyl esters derived from them; the polyethers in the carrier are addition products of propylene glycol, glycerol, and propylene oxide, with a molecular weight of 2000-5000.

3. The defoaming composition according to claim 1, characterized in that, The hydrophobic silica mentioned is a mixture of precipitated hydrophobic silica and fumed hydrophobic silica, with no limit on the mass ratio between the two.

4. The defoaming composition according to claim 1, characterized in that, The organic solid wax is a mixture of waxes with melting points below 100°C and above 100°C, and the difference between their melting point ranges is greater than 40°C. The mass ratio of high-melting-point wax to low-melting-point wax is not limited.

5. The defoaming composition according to claim 1, characterized in that, The method for synthesizing the polyether organosilicon copolymer is as follows: after adding glycerol polyether to a container and starting the stirrer, hydroxyl-terminated polysiloxane is added according to the molar ratio, and then potassium hydroxide catalyst is added at 0.5% of the total mass of the reactants. The reaction is carried out under negative pressure at 100-200℃ and maintained at -0.01 to -0.08 MPa for 2-10 hours.

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