High-corrosion-resistance water-based acrylic emulsion as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metal corrosion protection, and provides a high-corrosion-resistance water-based acrylic emulsion as well as a preparation method and application thereof. The method comprises the following steps: mixing a reactive vegetable oil phosphate surfactant, a coalescing agent, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid, homogenizing, and adding ammonia water to obtain a pre-emulsion; mixing a reactive vegetable oil phosphate surfactant, sodium bicarbonate and water to obtain a base solution; mixing the base solution, a part of the pre-emulsion and an initiator solution for reaction to obtain a seed emulsion; and mixing the seed emulsion, the residual pre-emulsion and the initiator solution for reaction, adding an oxidant solution and a reducing agent solution after the reaction is finished for reaction, and finally adding ammonia water to obtain the product. The reactive vegetable oil phosphate surfactant and the coalescing agent are reasonably adopted, the effect that the emulsion is free of gel residues is successfully achieved, and the coating is free of flash rust and high in corrosion resistance after being coated on carbon steel.

Description

Technical Field

[0001] The invention relates to the technical field of metal corrosion protection, and in particular to a high-corrosion-resistant water-based acrylic emulsion and a preparation method and application thereof. Background Art

[0002] Metal corrosion is a major problem faced by various industries, causing huge economic losses and safety issues. Therefore, corrosion inhibition has received great attention and extensive research. Among them, surface coating technology stands out as a widely used and cost-effective technology. By applying a protective coating on the metal surface, its corrosion resistance can be greatly enhanced, thereby improving durability. This method effectively shields the metal from contact with the corrosive medium, ultimately reducing the corrosion process. Water-based coatings are well known for their environmental benefits and ability to reduce VOC emissions, making them a preferred choice for different industries. Among water-based coatings, water-based acrylic coatings stand out in the field of metal corrosion protection due to their high cost-effectiveness, good weather resistance, chemical resistance, and good mechanical properties. However, compared with solvent-based coatings, water-based acrylic emulsions have obvious defects in coating density and flash rust protection. In addition, traditional non-reactive emulsifiers used in water-based acrylic coatings are prone to desorption and migration, and hydrophilic substances such as emulsifiers remain, which will inevitably reduce the corrosion resistance of the latex after film formation and affect product performance. At the same time, a large amount of gel residue will appear in the preparation process of water-based acrylic emulsions, which also affects the stability of acrylic emulsion products. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a highly corrosion-resistant water-based acrylic emulsion and a preparation method and application thereof.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a highly corrosion-resistant water-based acrylic emulsion, comprising the following steps:

[0006] (1) mixing a reactive vegetable oil phosphate surfactant, a film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid, homogenizing, and adding ammonia water after homogenization to obtain a pre-emulsion;

[0007] (2) mixing a reactive vegetable oil phosphate surfactant, sodium bicarbonate and water to obtain a base solution;

[0008] (3) mixing an initiator and water to obtain an initiator solution;

[0009] (4) mixing the base liquid, the first part of the pre-emulsion and the first part of the initiator solution, and reacting them to obtain a seed emulsion;

[0010] (5) mixing the seed emulsion, the remaining pre-emulsion and the remaining initiator solution to carry out a first reaction, adding an oxidant solution and a reducing agent solution to carry out a second reaction, and adding aqueous ammonia to obtain a highly corrosion-resistant water-based acrylic emulsion after the first reaction is completed;

[0011] There is no particular order among step (1), step (2) and step (3).

[0012] Preferably, the reactive vegetable oil phosphate surfactant in step (1) includes one or more of alkyl phosphate esters, alkyl phosphate salts, aryl phosphate esters, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphate esters, alkyl alcohol amide phosphate salts, imidazoline phosphate esters, imidazoline phosphate salts, polymer polyphosphate esters, polymer polyphosphate salts and siloxane phosphate esters;

[0013] The film-forming aid in step (1) includes one or more of dodecyl alcohol ester, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol monomethyl ether, propylene glycol phenyl ether, hexylene glycol butyl ether acetate and ethyl 3-ethoxypropionate;

[0014] In step (1), the mass ratio of the reactive vegetable oil phosphate surfactant, the film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid is 6.5-8.5:6-14:160-180:170-190:81-100:10-15:15-18.

[0015] Preferably, the homogenization temperature in step (1) is 20 to 30° C., and the homogenization time is 5 to 15 minutes;

[0016] The mass fraction of the ammonia water in step (1) is 18-22%; the pH value of the pre-emulsion in step (1) is 8-9.

[0017] Preferably, the reactive vegetable oil phosphate surfactant in step (2) includes one or more of alkyl phosphate esters, alkyl phosphate salts, aryl phosphate esters, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphate esters, alkyl alcohol amide phosphate salts, imidazoline phosphate esters, imidazoline phosphate salts, polymer polyphosphate esters, polymer polyphosphate salts and siloxane phosphate esters;

[0018] In step (2), the mass ratio of the reactive vegetable oil phosphate surfactant, sodium bicarbonate and water is 1-2:0.5-1.5:50-70.

[0019] Preferably, the initiator in step (3) comprises one or more of hydrogen peroxide, persulfate, hydroperoxide, water-soluble azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride;

[0020] The mass ratio of the initiator to water in step (3) is 1.6-2.5:60-80.

[0021] Preferably, in step (4), the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is 20-40:300-600; the mass ratio of the first part of the initiator solution to the whole initiator solution is 20-30:60-90;

[0022] The reaction temperature in step (4) is 70-82° C., and the reaction time is 30-60 min.

[0023] Preferably, the oxidant solution in step (5) is a tert-butyl hydroperoxide solution, and the mass fraction of the oxidant solution is 8-12%; the reducing agent solution is an organic sulfonic acid sodium salt solution, and the mass fraction of the reducing agent is 8-12%;

[0024] The mass ratio of the styrene, butyl acrylate, methyl methacrylate and acrylic acid in step (1) to the oxidant solution and the reducing agent solution in step (5) is 250-350:3-7:3-7.

[0025] Preferably, the temperature of the first reaction in step (5) is 80-85° C. and the time is 1-2 h;

[0026] Step (5) The temperature of the second reaction is 60-65°C and the time is 1-2h;

[0027] The mass fraction of the ammonia water in step (5) is 18-22%; the pH value of the highly corrosion-resistant water-based acrylic emulsion in step (5) is 8-9.

[0028] The invention also provides the high corrosion resistant water-based acrylic emulsion prepared by the preparation method of the high corrosion resistant water-based acrylic emulsion.

[0029] The invention also provides application of the highly corrosion-resistant water-based acrylic emulsion in metal corrosion-resistant coatings.

[0030] The beneficial effects of the present invention are:

[0031] The present invention provides a method for preparing a highly corrosion-resistant water-based acrylic emulsion, comprising the following steps: mixing a reactive vegetable oil phosphate surfactant, a film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid, homogenizing, adding ammonia water after homogenization to obtain a pre-emulsion; mixing a reactive vegetable oil phosphate surfactant, sodium bicarbonate and water to obtain a base liquid; mixing an initiator and water to obtain an initiator solution; mixing the base liquid, a first part of the pre-emulsion and a first part of the initiator solution, reacting to obtain a seed emulsion; mixing the seed emulsion, the remaining pre-emulsion and the remaining initiator solution, performing a first reaction, adding an oxidant solution and a reducing agent solution after the first reaction, performing a second reaction, adding ammonia water after the second reaction, and obtaining a highly corrosion-resistant water-based acrylic emulsion. The present invention reasonably adopts a reactive vegetable oil phosphate surfactant to successfully prepare a tetrapolymer emulsion. After the emulsion is formed into a film, the phosphoric acid group and the metal undergo a passivation reaction, thereby losing hydrophilicity, avoiding the residual hydrophilic group, making it difficult for water molecules and salt ions to enter the coating film, and successfully achieving the coating on Q235 carbon steel without flash rust, and strong corrosion resistance, and the effect of 3.5wt% NaCl solution corrosion resistance on Q235 carbon steel for 600h, and the mechanical properties and adhesion properties of the emulsion coating film are both very excellent. In addition, the present invention uses a film-forming aid in the process of synthesizing the emulsion in advance, successfully solves the technical problem of serious gel residue, achieves the emulsion without gel residue, and does not need to add a film-forming aid when the emulsion is coated and film-formed in the later stage, reducing the process flow and greatly improving the stability of the emulsion. The preparation method in the present invention is simple, and has low VOC emissions, is environmentally friendly, and is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the reactive vegetable oil phosphate surfactant in the present invention;

[0033] Figure 2 It is a schematic diagram of the passivation effect between the phosphate group and the metal in the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a method for preparing a highly corrosion-resistant water-based acrylic emulsion, comprising the following steps:

[0035] (1) mixing a reactive vegetable oil phosphate surfactant, a film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid, homogenizing, and adding ammonia water after homogenization to obtain a pre-emulsion;

[0036] (2) mixing a reactive vegetable oil phosphate surfactant, sodium bicarbonate and water to obtain a base solution;

[0037] (3) mixing an initiator and water to obtain an initiator solution;

[0038] (4) mixing the base liquid, the first part of the pre-emulsion and the first part of the initiator solution, and reacting them to obtain a seed emulsion;

[0039] (5) mixing the seed emulsion, the remaining pre-emulsion and the remaining initiator solution to carry out a first reaction, adding an oxidant solution and a reducing agent solution to carry out a second reaction, and adding aqueous ammonia to obtain a highly corrosion-resistant water-based acrylic emulsion after the first reaction is completed;

[0040] There is no particular order among step (1), step (2) and step (3).

[0041] In the present invention, the structural schematic diagram of the reactive vegetable oil phosphate surfactant is as follows: Figure 1 shown.

[0042] In the present invention, the reactive vegetable oil phosphate surfactant in step (1) preferably includes one or more of alkyl phosphates, alkyl phosphate salts, aryl phosphates, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphates, alkyl alcohol amide phosphate salts, imidazoline phosphates, imidazoline phosphate salts, polymer polyphosphates, polymer polyphosphate salts and silicone phosphates, and more preferably includes soybean oil acrylate phosphate and / or castor oil acrylate phosphate.

[0043] In the present invention, soybean oil acrylate phosphate is prepared by conventional technical means in the art. Specifically, epoxidized soybean oil is used as a raw material, acrylic acid is reacted with epoxy groups under the catalysis of an amine compound catalyst, and then hydrogen phosphate is reacted with epoxy groups to obtain soybean oil acrylate phosphate. The chemical formula of the preparation is as follows:

[0044]

[0045] In the present invention, castor oil acrylate phosphate is prepared by conventional technical means in the art. Specifically, castor oil is used as a raw material, acrylic acid or acryloyl chloride is first reacted with hydroxyl groups in the presence of a catalyst, then phosphorus pentoxide is reacted with hydroxyl groups, and finally, sodium hydroxide is used to neutralize to obtain castor oil acrylate phosphate. The chemical formula of the preparation is as follows:

[0046]

[0047] In the present invention, the film-forming aid in step (1) preferably includes one or more of dodecyl alcohol ester, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol monomethyl ether, propylene glycol phenyl ether, hexylene glycol butyl ether acetate and 3-ethoxyethyl propionate.

[0048] In the present invention, in step (1), the mixing preferably comprises the following steps: stirring the reactive vegetable oil phosphate surfactant, the film-forming aid and water uniformly, and then adding a uniform mixture of styrene, butyl acrylate, methyl methacrylate and acrylic acid, completing the mixing and homogenizing.

[0049] In the present invention, the mass ratio of the reactive vegetable oil phosphate surfactant, film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid in step (1) is preferably 6.5-8.5:6-14:160-180:170-190:81-100:10-15:15-18, further preferably 7-8:8-12:165-175:175-189:85-94:11-14:16-17, and more preferably 7.2-7.5:9-10:168-170:178-180:88-90:12-13:16.2-16.5.

[0050] In the present invention, the homogenization temperature in step (1) is preferably 20-30°C, more preferably 22-28°C, and more preferably 25-26°C; the homogenization time is preferably 5-15 min, more preferably 7-13 min, and more preferably 9-10 min.

[0051] In the present invention, the mass fraction of the ammonia water in step (1) is preferably 18-22%, more preferably 19-21%, and more preferably 20%; the purpose of adding ammonia water is to adjust the pH value; the pH value of the pre-emulsion in step (1) is preferably 8-9, more preferably 8.2-8.8, and more preferably 8.5-8.6.

[0052] In the present invention, the reactive vegetable oil phosphate surfactant in step (2) preferably includes one or more of alkyl phosphates, alkyl phosphate salts, aryl phosphates, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphates, alkyl alcohol amide phosphate salts, imidazoline phosphates, imidazoline phosphate salts, polymer polyphosphates, polymer polyphosphate salts and silicone phosphates, and more preferably includes soybean oil acrylate phosphate and / or castor oil acrylate phosphate.

[0053] In the present invention, the mass ratio of the reactive vegetable oil phosphate surfactant, sodium bicarbonate and water in step (2) is preferably 1-2: 0.5-1.5: 50-70, more preferably 1.2-1.8: 0.7-1.3: 55-65, and more preferably 1.5-1.6: 1-1.1: 60-62.

[0054] In the present invention, the initiator in step (3) preferably includes one or more of hydrogen peroxide, persulfate, hydroperoxide, water-soluble azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride; the persulfate preferably includes one or more of ammonium persulfate, potassium persulfate and sodium persulfate.

[0055] In the present invention, the mass ratio of the initiator to water in step (3) is preferably 1.6-2.5:60-80, more preferably 1.8-2.3:65-75, and more preferably 2-2.1:70-72.

[0056] In the present invention, in step (4), the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is preferably 20-40:300-600, more preferably 25-35:350-550, more preferably 30-32:400-500; the mass ratio of the first part of the initiator solution to the whole initiator solution is preferably 20-30:60-90, more preferably 22-28:65-85, more preferably 24-25:70-80.

[0057] In the present invention, the reaction temperature in step (4) is preferably 70-82°C, more preferably 72-80°C, and more preferably 75-77°C; the stirring speed of the reaction is preferably 400-500 r / min, more preferably 420-470 r / min, and more preferably 450-460 r / min; the reaction time is preferably 30-60 min, more preferably 40-50 min, and more preferably 42-45 min.

[0058] In the present invention, in step (5), the mixing of the seed emulsion, the remaining pre-emulsion and the remaining initiator solution preferably comprises the following steps: heating the seed emulsion prepared in step (4), and after heating to the target temperature, slowly dripping the remaining pre-emulsion and the remaining initiator solution at the same time, and performing the first reaction in step (5) after the dripping is completed.

[0059] In the present invention, the target temperature for heating is preferably 80-85°C, more preferably 81-84°C, and more preferably 82-83°C; the total time for dropwise addition is preferably 3-4h, more preferably 3.2-3.8h, and more preferably 3.5-3.6h.

[0060] In the present invention, the temperature of the first reaction in step (5) is preferably 80-85°C, more preferably 81-84°C, more preferably 82-83°C; the time is preferably 1-2h, more preferably 1.2-1.8h, more preferably 1.5-1.6h.

[0061] In the present invention, in step (5), after the first reaction is completed, the temperature is lowered, and after the temperature is lowered to the target temperature, the oxidant solution and the reductant solution are added dropwise at the same time. After the addition is completed, the second reaction is carried out.

[0062] In the present invention, the oxidant solution in step (5) is preferably tert-butyl hydroperoxide solution, and the mass fraction of the oxidant solution is preferably 8-12%, more preferably 9-11%, and more preferably 10-10.5%; the reducing agent solution is preferably an organic sulfinic acid sodium salt solution, and the organic sulfinic acid sodium salt solution is preferably an organic sulfinic acid sodium salt FF6M solution; the mass fraction of the reducing agent is preferably 8-12%, more preferably 9-11%, and more preferably 10-10.5%.

[0063] In the present invention, the mass ratio of the styrene, butyl acrylate, methyl methacrylate and acrylic acid in step (1) to the mass ratio of the oxidant solution and the reducing agent solution in step (5) is preferably 250-350:3-7:3-7, more preferably 275-325:4-6:4-6, and more preferably 300:5:5.

[0064] In the present invention, the target temperature for cooling is preferably 60-65°C, more preferably 61-64°C, and more preferably 62-63°C; the total time for dropping is preferably 0.3-0.7h, more preferably 0.4-0.6h, and more preferably 0.5-0.55h.

[0065] In the present invention, the oxidant solution and the reductant solution are added dropwise simultaneously to form a redox initiation system, and free radicals are generated through redox reaction, thereby initiating polymerization of monomers.

[0066] In the present invention, the temperature of the second reaction in step (5) is preferably 60-65°C, more preferably 61-64°C, more preferably 62-63°C; the time is preferably 1-2h, more preferably 1.2-1.8h, more preferably 1.5-1.6h.

[0067] In the present invention, in step (5), after the second reaction is completed, the temperature is lowered to room temperature, aqueous ammonia is added to adjust the pH value, and finally the mixture is sieved to obtain a highly corrosion-resistant water-based acrylic emulsion.

[0068] In the present invention, the mass fraction of the ammonia water in step (5) is preferably 18-22%, more preferably 19-21%, and more preferably 20%; the pH value of the highly corrosion-resistant aqueous acrylic emulsion in step (5) is preferably 8-9, more preferably 8.2-8.8, and more preferably 8.5-8.6.

[0069] In the present invention, the mesh size of the sieve is preferably 50 to 150 meshes, more preferably 70 to 130 meshes, and even more preferably 100 meshes.

[0070] The invention also provides the high corrosion resistant water-based acrylic emulsion prepared by the preparation method of the high corrosion resistant water-based acrylic emulsion.

[0071] The invention also provides application of the highly corrosion-resistant water-based acrylic emulsion in metal corrosion-resistant coatings.

[0072] In the present invention, the application preferably includes the following steps: polishing, ultrasonic cleaning and drying the metal surface in sequence to complete the pretreatment of the metal surface; scraping a highly corrosion-resistant water-based acrylic emulsion on the metal surface, and after the scraping is completed, standing at room temperature, and then drying to obtain a metal including a corrosion-resistant coating.

[0073] In the present invention, after the high corrosion-resistant water-based acrylic emulsion forms a film, the phosphoric acid group and the metal undergo a passivation reaction, thereby losing the hydrophilicity, avoiding the residual hydrophilic group, and making it difficult for water molecules and salt ions to enter the coating film; a schematic diagram of the passivation reaction between the phosphoric acid group and the metal in the present invention, as shown in FIG. Figure 2 shown.

[0074] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0075] Example 1

[0076] Weigh 6.5g of reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate), 6g of film-forming aid (dodecanol ester), and 170g of deionized water, stir evenly in a large beaker for later use, weigh 189g of styrene, 81g of butyl acrylate, 15g of methyl methacrylate, and 15g of acrylic acid, mix the four monomers evenly and pour them into a large beaker, homogenize them together at 25°C for 10min, and after homogenization, adjust the pH value to 8 with 20% ammonia water to obtain a pre-emulsion; weigh 1.5g of reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate), 1g of sodium bicarbonate, and 60g of deionized water, add them to a dry four-necked flask, mix evenly, and obtain a base solution; weigh 1.6g of initiator (potassium persulfate) and 70g of deionized water, stir evenly, and obtain an initiator solution;

[0077] Take the pre-emulsion (the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is 30:482.5) and the initiator solution (the mass ratio of the first part of the initiator solution to the whole initiator solution is 24:71.6) and add them to the base liquid, heat it to 82°C for reaction, set the stirring speed of the reaction to 400r / min, the reaction time to 30min, and obtain the seed emulsion after the reaction is completed; heat it to 85°C, and slowly drip the remaining pre-emulsion and the remaining initiator solution at the same time, the total dripping time is 3h, After the addition is completed, the mixture is reacted at 85°C for 1.5 hours. After the reaction is completed, the temperature is adjusted to 60°C, and 5g of a 10% by mass tert-butyl hydroperoxide solution and 5g of a 10% by mass organic sulfinic acid sodium salt FF6M solution are added simultaneously. The total dropwise addition time is 0.5h. After the addition is completed, the mixture is reacted at 60°C for 1 hour. After the reaction is completed, the mixture is cooled to room temperature, and the pH value is adjusted to 8 with 20% by mass ammonia water. Finally, the mixture is filtered through a 100-mesh molecular sieve to obtain a highly corrosion-resistant water-based acrylic emulsion.

[0078] Example 2

[0079] Weigh 7.5g of reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate), 12g of film-forming aid (hexanediol butyl ether acetate), and 170g of deionized water, stir them evenly in a large beaker for later use, weigh 180g of styrene, 94g of butyl acrylate, 10g of methyl methacrylate, and 16g of acrylic acid, mix the four monomers evenly and pour them into a large beaker, homogenize them together at 25°C for 10min, and after homogenization, adjust the pH value to 8.5 with 20% ammonia water to obtain a pre-emulsion; weigh 1.5g of reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate), 1g of sodium bicarbonate, and 60g of deionized water, add them to a dry four-necked flask, mix them evenly, and obtain a base liquid; weigh 2g of initiator (ammonium persulfate) and 70g of deionized water, stir them evenly, and obtain an initiator solution;

[0080] Take the pre-emulsion (the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is 30:489.5) and the initiator solution (the mass ratio of the first part of the initiator solution to the whole initiator solution is 24:72) and add them to the base liquid, heat it to 75℃ for reaction, set the stirring speed of the reaction to 450r / min, the reaction time to 50min, and obtain the seed emulsion after the reaction is completed; heat it to 85℃, and slowly drip the remaining pre-emulsion and the remaining initiator solution at the same time, the total dripping time is 3h, and drip it After the reaction, the mixture was reacted at 85°C for 1 hour. After the reaction, the temperature was adjusted to 65°C, and 5g of 10% tert-butyl hydroperoxide solution and 5g of 10% organic sodium sulfinate FF6M solution were added dropwise at the same time. The total time of the addition was 0.5h. After the addition, the mixture was reacted at 65°C for 1.5h. After the reaction, the mixture was cooled to room temperature, and the pH value was adjusted to 8.5 with 20% ammonia water. Finally, the mixture was filtered through a 100-mesh molecular sieve to obtain a highly corrosion-resistant water-based acrylic emulsion.

[0081] Example 3

[0082] Weigh 8.5g of reactive vegetable oil phosphate surfactant (castor oil acrylate phosphate), 14g of film-forming aid (ethyl 3-ethoxypropionate), and 170g of deionized water, stir them evenly in a large beaker for later use, weigh 170g of styrene, 100g of butyl acrylate, 12g of methyl methacrylate, and 18g of acrylic acid, mix the four monomers evenly and pour them into a large beaker, homogenize them together at 25°C for 10min, and after homogenization, adjust the pH value to 9 with 20% ammonia water by mass to obtain a pre-emulsion; weigh 1.5g of reactive vegetable oil phosphate surfactant (castor oil acrylate phosphate), 1g of sodium bicarbonate, and 60g of deionized water, add them to a dry four-necked flask, mix them evenly, and obtain a base liquid; weigh 2.5g of initiator (sodium persulfate) and 70g of deionized water, stir them evenly, and obtain an initiator solution;

[0083] Take the pre-emulsion (the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is 30:492.5) and the initiator solution (the mass ratio of the first part of the initiator solution to the whole initiator solution is 24:72.5) and add them to the base liquid, heat it to 70°C for reaction, set the stirring speed of the reaction to 500r / min, the reaction time to 60min, and obtain the seed emulsion after the reaction is completed; heat it to 80°C, and slowly drip the remaining pre-emulsion and the remaining initiator solution at the same time, and the total dripping time is 4h After the addition is completed, react at 80°C for 2 hours. After the reaction is completed, adjust the temperature to 63°C, and simultaneously add 5g of 10% by mass tert-butyl hydroperoxide solution and 5g of 10% by mass organic sulfinic acid sodium salt FF6M solution. The total time of dropwise addition is 0.5h. After the addition is completed, react at 63°C for 2 hours. After the reaction is completed, cool to room temperature, adjust the pH value to 9 with 20% by mass ammonia water, and finally pass through a 100-mesh molecular sieve to obtain a highly corrosion-resistant water-based acrylic emulsion.

[0084] Comparative Example 1

[0085] The other conditions in Example 1 were kept unchanged, and the addition of the film-forming aid was omitted to obtain an aqueous acrylic emulsion.

[0086] Comparative Example 2

[0087] While keeping other conditions in Example 1 unchanged, 6.5 g of the reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate) in the pre-emulsion was replaced by 6.5 g of sodium dodecyl sulfate, and 1.5 g of the reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate) in the base solution was replaced by 1.5 g of sodium dodecyl sulfate to obtain an aqueous acrylic emulsion.

[0088] Comparative Example 3

[0089] The other conditions in Example 2 were kept unchanged, and the addition of the film-forming aid was omitted to obtain an aqueous acrylic emulsion.

[0090] Comparative Example 4

[0091] The other conditions in Example 2 were controlled to remain unchanged, and 7.5 g of the reactive vegetable oil phosphate surfactant (soybean oil acrylate phosphate) in the pre-emulsion was replaced with 7.5 g of sodium dodecyl sulfate to obtain an aqueous acrylic emulsion.

[0092] The performance of the highly corrosion-resistant water-based acrylic emulsions obtained in Examples 1 to 3 and the water-based acrylic emulsions obtained in Comparative Examples 1 to 4 was tested, and the performance test results of different emulsions were obtained, as shown in Table 1. The gel fraction was determined by: the condensate filtered out after the emulsion was filtered through a 100-mesh screen and the condensate scraped off the bottle wall, the stirring rod and the thermometer were washed with distilled water for multiple times, baked in an oven at 80°C for 3 hours, weighed, and the gel fraction was determined using the formula: Calculate the gel fraction, where M 1 is the mass of the solid gel after drying, g; M is the total mass of the monomer, g. The method for determining the solid content is specifically based on the national standard "GB-1725-79 Petri dish method". The calculation formula for determining the conversion rate is as follows: In the formula, GH is the solid content, M 1 is the total mass of deionized water, g; M 2 is the total mass of the initiator and the reactive vegetable oil phosphate surfactant, g; M 3 is the total mass of the monomer, g. Ca 2+ The specific method for determining the stability is as follows: add 5 mL of the emulsion into a test tube, and then add 5 mL of 0.5% CaCl 2 The solution is stirred evenly and allowed to stand for 24 hours to observe whether there is coagulation or stratification. The determination method of dilution stability refers to the test in GB-T 1603-2001. The determination method of storage stability refers to the test in GB / T 16497-2007.

[0093] Table 1 Performance test results of different emulsions

[0094]

[0095] A Q235 steel sheet of 5cm×5cm×1mm was selected, and the surface of the steel sheet was polished with 180-mesh and 600-mesh sandpapers in sequence to remove rust and stains on the surface; then, the polished steel sheet was ultrasonically cleaned in acetone for 30 minutes, and then ultrasonically cleaned in alcohol for 30 minutes. Finally, the cleaned steel sheet was dried to complete the pretreatment of the surface of the steel sheet; the highly corrosion-resistant aqueous acrylic emulsions obtained in Examples 1 to 3 and the aqueous acrylic emulsions obtained in Comparative Examples 1 to 4 were respectively scraped on the surface of the steel sheet using a scraper. After the scraping, the steel sheet was allowed to stand at room temperature for 1 hour, and then placed in an oven at 45°C for drying for 20 to 30 minutes, with a dry film thickness of 130±5um. The test adopts the classic three-electrode system, in which the saturated AgCl electrode is the reference electrode, the platinum sheet is the auxiliary electrode, and the Q235 steel sheet coated with the emulsion coating is the working electrode; the adhesion test refers to the national standard GB / T 9286, the impact resistance test is based on GB / T 1732-2020, the hardness test refers to the national standard GB / T 6739, and the salt water resistance test refers to the national standard GB / T 9274. The performance test results of different emulsion coatings are shown in Table 2.

[0096] Table 2 Performance test results of different latex coatings

[0097]

[0098] As shown in Table 1 and Table 2, in Examples 1 to 3, reactive vegetable oil phosphate surfactants and film-forming aids were added during the preparation of the pre-emulsion, and reactive vegetable oil phosphate surfactants were added during the preparation of the base solution. The resulting emulsions all had zero gel residue rate, and at the same time had a high emulsion solid content and conversion rate, and had high stability. The coating also had strong impact resistance, and could withstand 3.5% NaCl salt water corrosion for up to 600 hours. In Comparative Examples 1 to 4, the residue gel rate was high, and the emulsion solid content and conversion rate were low, the impact resistance was poor, and the time of resistance to 3.5% NaCl salt water corrosion was also short. Therefore, it can be fully explained that the present invention adds reactive vegetable oil phosphate surfactants during the preparation of the pre-emulsion and the base solution, and can fully react during the reaction process, thereby improving the stability of the product, and improving its solid content and conversion rate. At the same time, after film formation, the phosphoric acid group and the metal undergo passivation, thereby losing hydrophilicity, avoiding the residual hydrophilic group, making it difficult for water molecules and salt ions to enter the coating film, and successfully solving the technical problems of flash rust after film formation of acrylic emulsion water-based anticorrosive coatings, and poor corrosion resistance due to residual hydrophilic groups. In addition, during the preparation process, the present invention uses a film-forming aid in advance in the process of synthesizing the emulsion, successfully solving the technical problem of serious gel residue, achieving emulsion without gel residue, and greatly improving the stability of the emulsion.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a highly corrosion-resistant water-based acrylic emulsion, characterized in that: It includes the following steps: (1) mixing a reactive vegetable oil phosphate surfactant, a film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid, homogenizing, and adding ammonia water after homogenization to obtain a pre-emulsion; (2) mixing a reactive vegetable oil phosphate surfactant, sodium bicarbonate and water to obtain a base solution; (3) mixing an initiator and water to obtain an initiator solution; (4) mixing the base liquid, the first part of the pre-emulsion and the first part of the initiator solution, and reacting them to obtain a seed emulsion; (5) mixing the seed emulsion, the remaining pre-emulsion and the remaining initiator solution to carry out a first reaction, adding an oxidant solution and a reducing agent solution to carry out a second reaction, and adding aqueous ammonia to obtain a highly corrosion-resistant water-based acrylic emulsion after the first reaction is completed; There is no particular order among step (1), step (2) and step (3).

2. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 1, characterized in that: The reactive vegetable oil phosphate surfactant in step (1) includes one or more of alkyl phosphates, alkyl phosphate salts, aryl phosphates, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphates, alkyl alcohol amide phosphate salts, imidazoline phosphates, imidazoline phosphate salts, polymer polyphosphates, polymer polyphosphate salts and siloxane phosphates; The film-forming aid in step (1) includes one or more of dodecyl alcohol ester, benzyl alcohol, ethylene glycol, propylene glycol, hexylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol monomethyl ether, propylene glycol phenyl ether, hexylene glycol butyl ether acetate and ethyl 3-ethoxypropionate; In step (1), the mass ratio of the reactive vegetable oil phosphate surfactant, the film-forming aid, water, styrene, butyl acrylate, methyl methacrylate and acrylic acid is 6.5-8.5:6-14:160-180:170-190:81-100:10-15:15-18.

3. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 1 or 2, characterized in that: The homogenization temperature in step (1) is 20 to 30° C., and the homogenization time is 5 to 15 minutes; The mass fraction of the ammonia water in step (1) is 18-22%; the pH value of the pre-emulsion in step (1) is 8-9.

4. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 3, characterized in that: The reactive vegetable oil phosphate surfactant in step (2) includes one or more of alkyl phosphates, alkyl phosphate salts, aryl phosphates, aryl phosphate salts, fatty alcohol polyoxyethylene ether phosphate salts, alkylphenol polyoxyethylene ether phosphate salts, alkyl alcohol amide phosphates, alkyl alcohol amide phosphate salts, imidazoline phosphates, imidazoline phosphate salts, polymer polyphosphates, polymer polyphosphate salts and siloxane phosphates; In step (2), the mass ratio of the reactive vegetable oil phosphate surfactant, sodium bicarbonate and water is 1-2:0.5-1.5:50-70.

5. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 1 or 4, characterized in that: The initiator in step (3) includes one or more of hydrogen peroxide, persulfate, hydroperoxide, water-soluble azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride; The mass ratio of the initiator to water in step (3) is 1.6-2.5:60-80.

6. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 5, characterized in that: In step (4), the mass ratio of the first part of the pre-emulsion to the whole pre-emulsion is 20-40:300-600; the mass ratio of the first part of the initiator solution to the whole initiator solution is 20-30:60-90; The reaction temperature in step (4) is 70-82° C., and the reaction time is 30-60 min.

7. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 6, characterized in that: In step (5), the oxidant solution is a tert-butyl hydroperoxide solution, and the mass fraction of the oxidant solution is 8-12%; the reducing agent solution is an organic sulfonic acid sodium salt solution, and the mass fraction of the reducing agent is 8-12%; The mass ratio of the styrene, butyl acrylate, methyl methacrylate and acrylic acid in step (1) to the oxidant solution and the reducing agent solution in step (5) is 250-350:3-7:3-7.

8. The method for preparing the highly corrosion-resistant aqueous acrylic emulsion according to claim 7, characterized in that: Step (5) The temperature of the first reaction is 80-85°C and the time is 1-2h; Step (5) The temperature of the second reaction is 60-65°C and the time is 1-2h; The mass fraction of the ammonia water in step (5) is 18-22%; the pH value of the highly corrosion-resistant water-based acrylic emulsion in step (5) is 8-9.

9. The highly corrosion-resistant water-based acrylic emulsion prepared by the method for preparing the highly corrosion-resistant water-based acrylic emulsion according to any one of claims 1 to 8.

10. Use of the highly corrosion-resistant aqueous acrylic emulsion according to claim 9 in metal corrosion-resistant coatings.

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