Water-based acrylic emulsion as well as preparation method and application thereof

Abstract

The invention discloses a water-based acrylic emulsion as well as a preparation method and application thereof. Emulsion particles in the water-based acrylic emulsion have a core-shell structure, the core is formed by copolymerizing methyl methacrylate or styrene and butyl acrylate, and the shell is formed by copolymerizing methyl methacrylate or styrene, butyl acrylate and a phosphate emulsifier ANPEO10-P1. A film formed by the waterborne acrylic emulsion is excellent in corrosion resistance, flash rust resistance and thermal stability and large in adhesive force, and the preparation method of the waterborne acrylic emulsion has the advantages of being easy to operate, low in VOC emission, environmentally friendly and the like and is suitable for large-scale industrial production and application.

Description

Technical Field

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

[0002] Metal corrosion is a major problem faced by all industries. It not only causes huge economic losses, but also leads to serious safety hazards. Therefore, metal corrosion protection has attracted widespread attention and research. There are many methods for metal corrosion protection, and surface coating technology stands out as a widely used and cost-effective metal corrosion protection technology. In industrial environments, by applying a protective coating on the metal surface, the corrosion resistance of the metal can be greatly enhanced, thereby improving the durability of the metal. Water-based paint is safe, environmentally friendly, and easy to use. After film formation, the paint film has good weather resistance, chemical resistance, and mechanical properties. It has a very broad application prospect in the field of metal corrosion protection. Water-based acrylic emulsion is a small-particle, multi-purpose, and excellent performance emulsion. After film formation, the coating film has excellent water resistance and weather resistance, and is often used as a film-forming resin for water-based coatings. However, most of the existing water-based acrylic emulsions have problems such as low density of the film after film formation, poor flash rust resistance, and easy desorption and migration of emulsifiers that affect the performance of the film, which makes it difficult to fully meet the requirements of actual applications.

[0003] Therefore, it is of great significance to develop a water-based acrylic emulsion with high film density, excellent anti-flash rust performance and stable performance after film formation. Summary of the invention

[0004] The purpose of the present invention is to provide an aqueous acrylic emulsion and a preparation method and application thereof.

[0005] The technical solution adopted by the present invention is:

[0006] A water-based acrylic emulsion, wherein the emulsion particles have a core-shell structure, the core is copolymerized by methyl methacrylate or styrene and butyl acrylate, and the shell is copolymerized by methyl methacrylate or styrene, butyl acrylate and phosphate emulsifier ANPEO 10 -P1 copolymerization.

[0007] A method for preparing the aqueous acrylic emulsion as described above comprises the following steps:

[0008] 1) dispersing a surfactant, an initiator and a pH adjuster in water, and then adding a mixed monomer consisting of methyl methacrylate or styrene and butyl acrylate to carry out a polymerization reaction to obtain a seed emulsion;

[0009] 2) Add the initiator to the seed emulsion, and then add methyl methacrylate or styrene, butyl acrylate and phosphate emulsifier ANPEO 10-P1 is dispersed in water to prepare a pre-emulsion, and then subjected to polymerization reaction to obtain a pre-polymer emulsion;

[0010] 3) Adding tert-butyl hydroperoxide and organic sulfinic acid sodium salt into the prepolymer emulsion to carry out polymerization reaction, thus obtaining a water-based acrylic emulsion.

[0011] Preferably, the surfactant in step 1) is at least one of potassium laurate, sodium dodecyl diphenyl ether disulfonate, potassium oleate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium stearate and sodium palmitate.

[0012] Preferably, the amount of the surfactant in step 1) is 0.8% to 3.0% of the mass of the mixed monomers.

[0013] Preferably, the initiator in step 1) is at least one of hydrogen peroxide, persulfate, hydroperoxide, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride.

[0014] Preferably, the amount of the initiator in step 1) is 0.2% to 1.5% of the mass of the mixed monomers.

[0015] Preferably, the pH adjuster in step 1) is at least one of sodium carbonate, sodium bicarbonate, sodium citrate and potassium citrate.

[0016] Preferably, the amount of the pH adjuster in step 1) is 0.9% to 3.0% of the mass of the mixed monomers.

[0017] Preferably, in step 1), the mass ratio of methyl methacrylate to butyl acrylate is 1:0.5-2.0.

[0018] Preferably, in step 1), the mass ratio of styrene to butyl acrylate is 1:0.5-2.0.

[0019] Preferably, the mixed monomers in step 1) are added dropwise at a uniform speed, and the addition is completed over 3 to 4 hours.

[0020] Preferably, the polymerization reaction in step 1) is carried out at a temperature of 70° C. to 85° C., and the reaction time is 1 h to 2 h.

[0021] Preferably, the polymerization reaction in step 1) is carried out under a protective atmosphere and at a stirring speed of 200 rpm to 500 rpm.

[0022] Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0023] Preferably, the initiator in step 2) is at least one of hydrogen peroxide, persulfate, hydroperoxide, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride.

[0024] Preferably, the amount of the initiator in step 2) is 0.1% to 0.6% of the mass of the seed emulsion.

[0025] Preferably, in step 2), the seed emulsion, methyl methacrylate, butyl acrylate, phosphate emulsifier ANPEO 10 -The mass ratio of P1 is 1:0.7~1.2:0.8~1.2:0.03~0.08.

[0026] Preferably, in step 2), the seed emulsion, styrene, butyl acrylate, phosphate emulsifier ANPEO 10 -The mass ratio of P1 is 1:0.7~1.2:0.8~1.2:0.03~0.08.

[0027] Preferably, the pH value of the pre-emulsion in step 2) is 7-8, and the pH value is adjusted with aqueous ammonia.

[0028] Preferably, the pre-emulsion in step 2) is added dropwise at a uniform speed, and the addition is completed over 3 to 4 hours.

[0029] Preferably, the polymerization reaction in step 2) is carried out at a temperature of 65° C. to 75° C., and the reaction time is 1 h to 2 h.

[0030] Preferably, the polymerization reaction in step 2) is carried out under a protective atmosphere and at a stirring speed of 200 rpm to 500 rpm.

[0031] Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0032] Preferably, the amount of tert-butyl hydroperoxide used in step 3) is 0.07% to 0.30% of the mass of the prepolymer emulsion.

[0033] Preferably, the tert-butyl hydroperoxide in step 3) is first prepared into an aqueous solution, and then added dropwise at a uniform speed over 20 to 60 minutes.

[0034] Preferably, the amount of the organic sulfinic acid sodium salt in step 3) is 0.07% to 0.30% of the mass of the prepolymer emulsion.

[0035] Preferably, in step 3), the organic sodium sulfinate salt is first prepared into an aqueous solution, and then added dropwise at a uniform speed over a period of 20 to 60 minutes.

[0036] Preferably, the tert-butyl hydroperoxide and the organic sulfinic acid sodium salt are added simultaneously in step 3). Tert-butyl hydroperoxide is an oxidizing agent, and the organic sulfinic acid sodium salt is an active reducing agent, and the two together constitute a redox initiator system, and the two parts with oxidizing and reducing properties generate free radicals through redox reactions, thereby initiating monomer polymerization.

[0037] Preferably, the polymerization reaction in step 3) is carried out at a temperature of 60° C. to 65° C., and the reaction time is 1 h to 2 h.

[0038] A water-based paint comprises the water-based acrylic emulsion.

[0039] Preferably, the water-based paint is a water-based anti-corrosion paint.

[0040] The beneficial effects of the present invention are as follows: the coating film formed by the water-based acrylic emulsion of the present invention has excellent corrosion resistance, excellent flash rust resistance, excellent thermal stability, and strong adhesion, and its preparation method has the advantages of simple operation, low VOC emission, and environmental friendliness, and is suitable for large-scale industrial production and application.

[0041] Specifically:

[0042] 1) The aqueous acrylic emulsion of the present invention is prepared by using a phosphate emulsifier ANPEO 10 -P1 is made by seed emulsion polymerization, which can be quickly dried and film-formed at room temperature. After film formation, the phosphate group and the metal undergo a passivation reaction, making it difficult for water molecules and salt ions to enter the coating, giving the coating excellent corrosion resistance and flash rust resistance (solving the problem of flash rust after film formation and poor corrosion resistance due to residual hydrophilic groups in traditional water-based acrylic emulsions), and is suitable for use in the field of metal corrosion protection;

[0043] 2) The aqueous acrylic emulsion of the present invention has a high solid content and Ca 2+ Excellent stability. The coating formed after film formation has excellent thermal stability and strong adhesion;

[0044] 3) The preparation method of the aqueous acrylic emulsion of the present invention is simple, has low VOC emission, does not involve any additional corrosion inhibitor, is environmentally friendly, and is conducive to large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the structure of the emulsion particles in the aqueous acrylic emulsion of the present invention.

[0046] Figure 2 This is the Nyquist diagram of the salt water immersion resistance of the coating film made from the water-based acrylic emulsion in Example 1.

[0047] Figure 3 This is the Nyquist diagram of the salt water immersion resistance of the coating film made from the water-based acrylic emulsion in Example 3. DETAILED DESCRIPTION

[0048] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0049] Embodiment 1:

[0050] A water-based acrylic emulsion, the preparation method of which is as follows:

[0051] 1) 0.63 g of sodium dodecyl diphenyl ether disulfonate, 0.313 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 80° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 31.3 g of methyl methacrylate and 31.3 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0052] 2) Add 0.163 g of potassium persulfate to 53.65 g of seed emulsion, and then stir and heat to 80° C. under argon protection at a stirring speed of 400 rpm, and then uniformly add 59.55 g of methyl methacrylate, 59.55 g of butyl acrylate, and 2.526 g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0053] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 2.5 g of 10% by mass tert-butyl hydroperoxide solution and 2.5 g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform rate for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain an aqueous acrylic emulsion (denoted as MMA-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (as shown in a in the figure).

[0054] Embodiment 2:

[0055] A water-based acrylic emulsion, the preparation method of which is as follows:

[0056] 1) 1 g of sodium dodecyl diphenyl ether disulfonate, 0.5 g of potassium persulfate and 1.5 g of sodium bicarbonate were added to 450 g of ionized water, and then stirred under argon protection and heated to 85° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 50 g of methyl methacrylate and 50 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0057] 2) Add 0.2g of potassium persulfate to 60g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 65g of methyl methacrylate, 65g of butyl acrylate, 3g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0058] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 3g of 10% by mass tert-butyl hydroperoxide solution and 3g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform speed for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain a water-based acrylic emulsion (denoted as MMA-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (as shown in a in the figure).

[0059] Embodiment 3:

[0060] A water-based acrylic emulsion (denoted as St-BA emulsion; the structural schematic diagram of the emulsion particles is shown in Figure 1 b), except that the mass of "methyl methacrylate" in step 1) and step 2) is replaced by "styrene", the rest is exactly the same as Example 1.

[0061] Embodiment 4:

[0062] A water-based acrylic emulsion, the preparation method of which is as follows:

[0063] 1) 1.5 g of sodium dodecyl diphenyl ether disulfonate, 0.4 g of potassium persulfate and 2 g of sodium bicarbonate were added to 500 g of ionized water, and then stirred under argon protection and heated to 85° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 40 g of styrene and 40 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0064] 2) Add 0.25g of potassium persulfate to 55g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 55g of styrene, 55g of butyl acrylate, and 2g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0065] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 2g of 10% by mass tert-butyl hydroperoxide solution and 2g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform rate for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain a water-based acrylic emulsion (denoted as St-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (as shown in b in the figure).

[0066] Embodiment 5:

[0067] A water-based acrylic emulsion, the preparation method of which is as follows:

[0068] 1) 0.65 g of sodium dodecyl diphenyl ether disulfonate, 0.4 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 75° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 45 g of methyl methacrylate and 33 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0069] 2) Add 0.2g of potassium persulfate to 55g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 50g of methyl methacrylate, 60g of butyl acrylate, 2.6g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 65°C and reacted at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0070] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 2.5 g of 10% by mass tert-butyl hydroperoxide solution and 2.5 g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform rate for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain an aqueous acrylic emulsion (denoted as MMA-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1(as shown in a in the figure).

[0071] Embodiment 6:

[0072] A water-based acrylic emulsion, the preparation method of which is as follows:

[0073] 1) 1 g of sodium dodecyl diphenyl ether disulfonate, 0.4 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 85° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 50 g of methyl methacrylate and 60 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0074] 2) Add 0.3g of potassium persulfate to 70g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 50g of methyl methacrylate, 60g of butyl acrylate, 3g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0075] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 3g of 10% by mass tert-butyl hydroperoxide solution and 3g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform speed for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain a water-based acrylic emulsion (denoted as MMA-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (as shown in a in the figure).

[0076] Embodiment 7:

[0077] A water-based acrylic emulsion, the preparation method of which is as follows:

[0078] 1) 0.7 g of sodium dodecyl diphenyl ether disulfonate, 0.2 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 70° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 50 g of styrene and 30 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0079] 2) Add 0.3g of potassium persulfate to 56g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 50g of styrene, 60g of butyl acrylate, 2.8g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0080] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 2.5 g of 10% by mass tert-butyl hydroperoxide solution and 2.5 g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform rate for 30 minutes. After the addition was completed, the mixture was reacted at a constant temperature for 1 hour to obtain a water-based acrylic emulsion (denoted as St-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (as shown in b in the figure).

[0081] Embodiment 8:

[0082] A water-based acrylic emulsion, the preparation method of which is as follows:

[0083] 1) 1.2 g of sodium dodecyl diphenyl ether disulfonate, 0.4 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 70° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 33 g of styrene and 33 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0084] 2) Add 0.35g of potassium persulfate to 58g of seed emulsion, and then stir and heat to 80°C under argon protection at a stirring speed of 400rpm, and then uniformly add 65g of styrene, 65g of butyl acrylate, 2.5g of phosphate emulsifier ANPEO 10 -P1 and 75g of deionized water were emulsified at high speed for 10min, and then the pH value was adjusted to 7 with ammonia water to obtain a pre-emulsion, and the temperature was kept constant for 4h, and then the temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 1h to obtain a pre-polymer emulsion;

[0085] 3) The temperature of the prepolymer emulsion was adjusted to 60°C, and 2g of 10% by mass tert-butyl hydroperoxide solution and 2g of 10% by mass organic sulfinic acid sodium salt (FF6) solution were added dropwise at a uniform rate for 30 minutes. After the addition was completed, the mixture was kept at a constant temperature for 1 hour to obtain a water-based acrylic emulsion (denoted as St-BA emulsion; the structural schematic diagram of the emulsion particles is shown in FIG. Figure 1 (b) in the figure). Comparative Example 1:

[0086] A water-based acrylic emulsion, in addition to the "phosphate emulsifier ANPEO" in step 2) during preparation 10 Except that the mass of "-P1" is replaced by "sodium dodecyl diphenyl ether disulfonate", the rest is exactly the same as Example 1.

[0087] Comparative Example 2:

[0088] A water-based acrylic emulsion, the preparation method of which is as follows:

[0089] 1) 0.63 g of sodium dodecyl diphenyl ether disulfonate, 0.3 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 80° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 31.3 g of styrene and 31.3 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0090] 2) adding 0.28 g of potassium persulfate to 53.65 g of seed emulsion, stirring and heating to 80° C. under argon protection at a stirring speed of 400 rpm, then uniformly dropping 59.55 g of styrene, 59.55 g of butyl acrylate, 2.526 g of sodium dodecyl diphenyl ether disulfonate and 75 g of deionized water, emulsifying at high speed shear for 10 min, and then adjusting the pH value to 7 with ammonia water to obtain a pre-emulsion, and keeping the temperature constant for 4 h, and then adjusting the temperature to 70° C. and reacting at a constant temperature for 1 h to obtain a pre-polymer emulsion;

[0091] 3) The temperature of the prepolymer emulsion is adjusted to 60° C., and 2.5 g of a 10% by mass solution of tert-butyl hydroperoxide and 2.5 g of a 10% by mass solution of organic sodium sulfinate (FF6) are added dropwise at a uniform rate for 30 minutes. After the addition is completed, the mixture is reacted at a constant temperature for 1 hour to obtain a water-based acrylic emulsion.

[0092] Comparative Example 3:

[0093] A water-based acrylic emulsion, the preparation method of which is as follows:

[0094] 1) 1 g of sodium dodecyl diphenyl ether disulfonate, 0.2 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 75° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 50 g of methyl methacrylate and 50 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0095] 2) adding 0.5 g of potassium persulfate to 60 g of seed emulsion, stirring and heating to 80° C. under argon protection at a stirring speed of 400 rpm, then uniformly dropping 65 g of methyl methacrylate, 65 g of butyl acrylate, 3.5 g of sodium dodecyl diphenyl ether disulfonate and 75 g of deionized water, emulsifying at high speed shear for 10 min, and then adjusting the pH value to 7 with ammonia water to obtain a pre-emulsion, and keeping the temperature constant for 4 h, and then adjusting the temperature to 70° C. and reacting at a constant temperature for 1 h to obtain a pre-polymer emulsion;

[0096] 3) The temperature of the prepolymer emulsion is adjusted to 60° C., and 3 g of a 10% by mass solution of tert-butyl hydroperoxide and 3 g of a 10% by mass solution of an organic sodium sulfinate (FF6) are added dropwise at a uniform rate for 30 minutes. After the addition is completed, the mixture is reacted at a constant temperature for 1 hour to obtain a water-based acrylic emulsion.

[0097] Comparative Example 4:

[0098] A water-based acrylic emulsion, the preparation method of which is as follows:

[0099] 1) 1.5 g of sodium dodecyl diphenyl ether disulfonate, 0.5 g of potassium persulfate and 1.035 g of sodium bicarbonate were added to 436.7 g of ionized water, and then stirred under argon protection and heated to 75° C. at a stirring speed of 400 rpm, and then a mixed monomer consisting of 45 g of styrene and 40 g of butyl acrylate was uniformly added dropwise, and the temperature was kept constant for 4 hours. After the addition was completed, the constant temperature reaction was continued for 1 hour to obtain a seed emulsion;

[0100] 2) adding 0.15 g of potassium persulfate to 55 g of seed emulsion, stirring and heating to 80° C. under argon protection at a stirring speed of 400 rpm, then uniformly dropping 50 g of styrene, 55 g of butyl acrylate, 3 g of sodium dodecyl diphenyl ether disulfonate and 75 g of deionized water, emulsifying at high speed for 10 min, and then adjusting the pH value to 7 with ammonia water to obtain a pre-emulsion, and keeping the temperature constant for 4 h, and then adjusting the temperature to 70° C. and reacting at a constant temperature for 1 h to obtain a pre-polymer emulsion;

[0101] 3) The temperature of the prepolymer emulsion is adjusted to 60° C., and then 2 g of a 10% by mass solution of tert-butyl hydroperoxide and 2 g of a 10% by mass solution of organic sodium sulfinate (FF6) are added dropwise at a uniform rate for 30 minutes. After the addition is completed, the mixture is reacted at a constant temperature for 1 hour to obtain a water-based acrylic emulsion.

[0102] Note:

[0103] The raw material summary table of the preparation of the aqueous acrylic emulsions of Examples 1 to 8 and Comparative Examples 1 to 4 is as follows (unit: g):

[0104] Table 1 Summary of raw materials for the preparation of water-based acrylic emulsion

[0105]

[0106] Performance Test:

[0107] 1) The performance test results of the aqueous acrylic emulsions of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in the following table:

[0108] Table 2 Performance test results of water-based acrylic emulsion

[0109]

[0110]

[0111] Note:

[0112] Gel rate: Filter the emulsion through a 100-mesh sieve, collect the filtered coagulants and the coagulants scraped off the bottle wall, the stirring rod and the thermometer, wash them with distilled water for several times, and then bake them in an oven at 80°C for 3 hours, weigh them, and then calculate the gel rate according to the following formula: Gel rate (%) = M1 / M×100%, where M1 is the mass of the dried coagulant (in g), and M is the total mass of the monomer (in g).

[0113] Solid content: Test according to "GB 1725-1979 Standard for Determination of Solid Content of Coatings".

[0114] The conversion rate is calculated as follows: Conversion rate (%) = (M1 + M2 + M3) / M3 × GH%, where M1 is the mass of deionized water (in g), M2 is the mass of initiator and emulsifier (in g), M3 is the mass of monomer (in g), and GH is the solid content.

[0115] Ca + Stability: Add 5 mL of the emulsion into a test tube, then add 5 mL of a 0.5% CaC12 solution, stir evenly, let stand for 24 hours, and observe whether there is coagulation or stratification.

[0116] Adhesion: Test with reference to "GB / T 9286-2021 Paint and varnish cross-cut test".

[0117] Thermal decomposition temperature: Tested in accordance with "GB / T 33047.1-2016 Plastic polymer thermogravimetric method (TG) Part 1: General rules".

[0118] Water absorption rate: Apply the emulsion on a clean glass sheet, dry it in an oven to form a film, weigh it, then soak the film in water for 48 hours, take it out, dry the surface moisture, weigh it, and then calculate the percentage increase in the mass of the film after immersion in water.

[0119] As shown in Table 2, the phosphate emulsifier ANPEO was used in Examples 1 to 8. 10 -P1, the emulsions all have lower residual gel rate, higher emulsion solid content and conversion rate, and the film has stronger adhesion and higher thermal decomposition temperature after film formation. However, in Comparative Examples 1 to 4, the phosphate emulsifier ANPEO is not used. 10 -P1, the residual gel rate of the emulsion is relatively high, and the solid content and conversion rate of the emulsion are relatively low. The adhesion of the film after film formation is relatively weak and the thermal decomposition temperature is relatively low. It can be seen that the phosphate emulsifier ANPEO used in the present invention 10 -P1 has better hydrophilicity than ordinary emulsifiers and can fully react during the reaction process, thereby improving the stability of the emulsion and increasing the solid content and conversion rate of the emulsion. At the same time, after the emulsion forms a film, the phosphate groups in the emulsion can react with the hydroxyl groups on the surface of the metal substrate to form cross-linked phosphate groups through chelation. This effect can promote the close bonding between the coating and the metal surface and increase its adhesion.

[0120] 2) The surface of a Q235 steel sheet / 5052 aluminum alloy sheet with a size of 5 cm×5 cm×1 mm was polished with 600-mesh sandpaper to remove surface rust and stains, and then ultrasonically cleaned with acetone and alcohol for 30 min respectively, and then dried. The aqueous acrylic emulsions of Examples 1 to 8 and Comparative Examples 1 to 4 were then scraped on the surface of the Q235 steel sheet / 5052 aluminum alloy sheet with a scraper, and allowed to stand at room temperature to form a film with a thickness of 120 μm±10 μm. The salt water resistance of the coating was tested, and the test results are shown in the following table (the salt water immersion resistance Nyquist plot of the coating made of the aqueous acrylic emulsion of Example 1 is as follows Figure 2 As shown in the figure, a is a Q235 steel sheet coated with a paint film, and b is a 5052 aluminum alloy sheet coated with a paint film; the Nyquist diagram of the salt water immersion resistance of the coating film made of the water-based acrylic emulsion of Example 3 is as shown in Figure 3 As shown, a in the figure is a Q235 steel sheet coated with a paint film, and b is a 5052 aluminum alloy sheet coated with a paint film):

[0121] Table 3 Test results of salt water resistance of coatings made of water-based acrylic emulsion

[0122]

[0123]

[0124] Note:

[0125] Salt water resistance: The test was carried out in accordance with "GB / T 39482.3-2020 Electrochemical impedance spectroscopy (EIS) of painted and unpainted metal specimens Part 3: Processing and analysis of data obtained from simulated electrolytic cells". The classic three-electrode system was adopted, with a saturated AgCl electrode as the reference electrode, a platinum sheet as the auxiliary electrode, and a Q235 steel sheet / 5052 aluminum alloy sheet coated with a paint film as the working electrode.

[0126] From Table 3, Figure 2 and Figure 3 It can be seen that the phosphate emulsifier ANPEO was used in Examples 1 to 8. 10 -P1, whether the emulsion is formed on Q235 carbon steel or 5052 aluminum alloy, the coating film is better than that of the aqueous acrylic emulsion of comparative examples 1 to 4 (without phosphate emulsified ANPEO 10 -P1) have a longer corrosion resistance time of 3.5wt% salt water, and the coating has a stronger corrosion resistance. 10 The phosphate groups in -P1 can react with the hydroxyl groups on the surface of the metal substrate to form cross-linked phosphate groups through chelation. This effect can promote the close bonding between the coating and the metal surface, especially for Q235 carbon steel. After the iron phosphate passivation layer is formed on the carbon steel surface, it can further isolate the corrosive medium, thereby greatly improving the overall corrosion protection performance of the coating.

[0127] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A water-based acrylic emulsion, characterized in that: The emulsion particles have a core-shell structure. The core is made of copolymers of methyl methacrylate or styrene and butyl acrylate, and the shell is made of methyl methacrylate or styrene, butyl acrylate and phosphate emulsifier ANPEO. 10 -P1 copolymerization.

2. A method for preparing the aqueous acrylic emulsion according to claim 1, characterized in that: The following steps are involved: 1) dispersing a surfactant, an initiator and a pH adjuster in water, and then adding a mixed monomer consisting of methyl methacrylate or styrene and butyl acrylate to carry out a polymerization reaction to obtain a seed emulsion; 2) Add the initiator to the seed emulsion, and then add methyl methacrylate or styrene, butyl acrylate and phosphate emulsifier ANPEO 10 -P1 is dispersed in water to prepare a pre-emulsion, and then subjected to polymerization reaction to obtain a pre-polymer emulsion; 3) Adding tert-butyl hydroperoxide and organic sulfinic acid sodium salt into the prepolymer emulsion to carry out polymerization reaction, thus obtaining a water-based acrylic emulsion.

3. The preparation method according to claim 2, characterized in that: The surfactant in step 1) is at least one of potassium laurate, sodium dodecyl diphenyl ether disulfonate, potassium oleate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium stearate, and sodium palmitate; the initiator in step 1) is at least one of hydrogen peroxide, persulfate, hydroperoxide, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride; the pH adjuster in step 1) is at least one of sodium carbonate, sodium bicarbonate, sodium citrate, and potassium citrate.

4. The preparation method according to claim 2 or 3, characterized in that: The amount of the surfactant in step 1) is 0.8% to 3.0% of the mass of the mixed monomers; the amount of the initiator in step 1) is 0.2% to 1.5% of the mass of the mixed monomers; The amount of the pH regulator in step 1) is 0.9% to 3.0% of the mass of the mixed monomers.

5. The preparation method according to claim 2 or 3, characterized in that: The mass ratio of methyl methacrylate to butyl acrylate in step 1) is 1:0.5-2.0; the mass ratio of styrene to butyl acrylate in step 1) is 1:0.5-2.

0.

6. The preparation method according to claim 2 or 3, characterized in that: Step 1) The polymerization reaction is carried out at a temperature of 70°C to 85°C and the reaction time is 1h to 2h.

7. The preparation method according to claim 2, characterized in that: The initiator in step 2) is at least one of hydrogen peroxide, persulfate, hydroperoxide, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride; the amount of the initiator in step 2) is 0.1% to 0.6% by mass of the seed emulsion; the amount of tert-butyl hydroperoxide in step 3) is 0.07% to 0.30% by mass of the prepolymer emulsion; the amount of the organic sulfinic acid sodium salt in step 3) is 0.07% to 0.30% by mass of the prepolymer emulsion.

8. The preparation method according to claim 2 or 7, characterized in that: Step 2) the seed emulsion, methyl methacrylate, butyl acrylate, phosphate emulsifier ANPEO 10 -P1 mass ratio is 1:0.7~1.2:0.8~1.2:0.03~0.08; Step 2) the seed emulsion, styrene, butyl acrylate, phosphate emulsifier ANPEO 10 -The mass ratio of P1 is 1:0.7~1.2:0.8~1.2:0.03~0.

08.

9. The preparation method according to claim 2 or 7, characterized in that: The polymerization reaction in step 2) is carried out at a temperature of 65°C to 75°C, and the reaction time is 1h to 2h; the polymerization reaction in step 3) is carried out at a temperature of 60°C to 65°C, and the reaction time is 1h to 2h.

10. A water-based paint, characterized in that: The invention comprises the aqueous acrylic emulsion according to claim 1.

Images