A water-based acrylic rust-preventive resin and a method for preparing the same

Abstract

The application discloses a kind of water-based acrylate rust-proof resin and preparation method thereof.The water-based acrylate rust-proof resin contains pyrano [2,3-c] pyrazolyl on polymer chain, tertiary amine and phosphoric acid group, cyano, long-chain octadecyl and isobornyl group, etc., which can effectively inhibit the occurrence of metal surface flash rust, and has good salt fog resistance.The water-based acrylate rust-proof resin has good adhesion to substrate, water resistance, impact resistance, scratch resistance and coating toughness after drying, and has high gloss, without additional rust-proof pigment and filler, and can achieve good rust-proof effect.The water-based acrylate rust-proof resin can also be used with conventional water-based resin, and can be added at any stage of paint mixing, which can significantly improve the anti-flash rust ability of conventional water-based resin in early stage and the ability of sustained rust prevention in later stage.

Description

Technical Field

[0001] This invention belongs to the field of waterborne resin technology, specifically relating to a waterborne acrylic rust-preventive resin and its preparation method. Background Technology

[0002] With the development of water-based technology, water-based coatings are increasingly widely used in the light corrosion protection of metals. Because metals contain trace amounts of impurities during the smelting process, when water-based coatings are applied to metal surfaces, a galvanic cell forms between the water in the coating, a small amount of electrolyte in the coating, the metal itself, and the impurities within the metal. This easily leads to electrochemical corrosion of the metal surface, resulting in flash rust. After the coating dries on the metal surface, it forms a protective layer that can continuously protect the metal from water and oxygen corrosion. However, during long-term use, due to factors such as coating aging, mechanical damage, poor adhesion between the coating and the substrate, or insufficient density, the metal inside the coating can still be corroded by water and oxygen in the environment.

[0003] These two types of problems are the most common forms of rust on metals caused by water-based coatings. Flash rust is usually addressed by adding anti-flash rust additives. Common anti-flash rust additives include inorganic and organic small-molecule compounds such as sodium nitrite, sodium molybdate, strontium chromate, benzotriazole, benzisothiazoline derivatives, alkyl imidazoles, and mercaptobenzimidazoles. These anti-flash rust additives are criticized in the market due to their poor long-term protective ability or unfavorable environmental performance. Long-term rust prevention is usually achieved by adding rust-inhibiting pigments and fillers. Common rust-inhibiting pigments and fillers include zinc oxide, zinc-modified phosphates, and tripolyphosphates. These fillers typically have a high density, poor water resistance, and poor compatibility with emulsions, easily causing problems such as filler coarsening, affecting subsequent application.

[0004] CN105949366A provides a metal anti-rust emulsion. The emulsion's raw materials include 35-55 wt% vinyl monomers, 1.5-5 wt% a mixture of phosphate acrylate and active organosilanes, 0.5-3 wt% a mixture of acrylic acid or methacrylic acid and acrylamide, 1-7 wt% a mixed emulsifier containing phosphonic acid and sulfonic acid groups, 0.01-1% sulfonated halloysite nanotubes, 0.1-0.3 wt% initiator, 0.05-2.5 wt% pH adjuster, and 45-60 wt% water. This emulsion exhibits good adhesion and water resistance. Anti-rust waterborne coatings prepared using this emulsion as a base liquid possess excellent salt water and salt spray resistance, and provide excellent anti-rust capabilities for steel structures. However, this metal anti-rust emulsion has insufficient resistance to flash rust, requiring the addition of an anti-flash rust agent during the preparation of anti-rust waterborne coatings.

[0005] CN112538137B discloses a water-based rust-inhibiting polymer, which is polymerized from (meth)acrylonitrile, methacrylate or styrene, and itaconic acid with chelating properties at 100-150°C. A chain transfer agent is used during polymerization to maintain the molecular weight between 3000-10000. The polymer is then reacted with ammonia or a C1-C4 alkylamine under a catalyst at 120-150°C. This polymer effectively prevents flash rust during application and, as an additive in water-based coating systems, significantly improves the water resistance and rust prevention of the paint film, especially its salt spray resistance. However, the polymerization temperature exceeds the boiling point of (meth)acrylonitrile, requiring a high-pressure reactor, which places high demands on equipment and operators. Furthermore, due to the low molecular weight of the polymer, its film strength as an anti-corrosion material alone is insufficient to meet the strength requirements of metal surface coatings. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a water-based acrylic rust-inhibiting resin and its preparation method. The typical structural formula of the water-based acrylic rust-inhibiting resin is described below:

[0007] Wherein R1 and R2 are H; R3, R4, R5, R6 and R7 are each independently one of H, methyl, and ethyl; R8, R9, R 10 and R 11 Each of the following is an independent number of H, methyl, ethyl, n-butyl, 2-ethylhexyl, octadecyl, and isobornyl; a = 1 or 2; b, c, d, and e are independent natural numbers from 0 to 100 depending on the amount used in the formulation; f is a natural number from 0 to 8.

[0008] The present invention also provides a method for preparing the waterborne acrylic rust-inhibiting resin, comprising the following steps: Step 1: By weight, at 25-30℃, add 130 parts of ethyl acetoacetate and 400-500 parts of ethanol to a reaction vessel and stir. Add 62.5-65 parts of 80wt% hydrazine hydrate solution dropwise, stirring for 0.5-1 hour after the addition is complete. Then, add 56-175 parts of alkenyl aldehyde and 66-72 parts of malononitrile sequentially, stirring until homogeneous. Finally, add 13-17 parts of the catalyst Purolite. ® CTA193Plus, react for 8-12 hours, filter out the catalyst; add 50-80 parts of ethanol to wash the catalyst, and quickly pour the washing liquid and filtrate into 3000-4000 parts of deionized water to obtain a large amount of precipitate. Filter and wash the precipitate with 400 parts of 55wt% ethanol aqueous solution, and vacuum dry the precipitate at room temperature to obtain alkenylpyrano[2,3-c]pyrazole derivative.

[0009] Step 2: By weight, add 126-140 parts of dihydrogen phosphate and 200-250 parts of deionized water to the reactor, heat to 75-85℃, adjust the pH to 6-6.5 with 25wt% ammonia, add 92.5 parts of epichlorohydrin dropwise, maintain the temperature for 6-9 hours until the epichlorohydrin phase disappears, and cool to 20-30℃; then dissolve 68-104 parts of the alkenylpyrano[2,3-c]pyrazole derivative obtained in Step 1 in 500 parts of dichloromethane, and continue to add it to the reactor, along with 10-15 parts of the phase transfer catalyst PEG400. The temperature is raised to 33-38℃, and 300-320 parts of 40wt% sodium hydroxide solution are slowly added dropwise over 1-2 hours while stirring at 800rpm. The temperature is maintained for 4-6 hours. The temperature is lowered to 20-30℃, and the mixture is allowed to stand and separate into layers. The organic phase is washed with 1000 parts of 1mol / L hydrochloric acid, followed by 1000 parts of deionized water three times. The aqueous phase is discarded. 150 parts of 25wt% ammonia water are added to the organic phase and stirred for 0.5-1 hours. The aqueous phase is discarded. Dichloromethane is removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt.

[0010] Step 3: Dissolve 5-7 parts by weight of reactive emulsifier in 180-210 parts of deionized water, and add dropwise a mixed monomer consisting of 200-230 parts of short-chain mixed monomers and 3-5 parts of unsaturated carboxylic acids. Stir at 600-800 rpm for 0.5-1 hours to obtain pre-emulsion A; Dissolve 10-15 parts by weight of reactive emulsifier in 160-190 parts of deionized water, and add dropwise a mixed monomer consisting of 30 parts of alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt, 140-160 parts of short-chain mixed monomers, 8-10 parts of unsaturated carboxylic acids, 15-18 parts of long-chain acrylate monomers, and 18-25 parts of cyclic acrylate monomers. Stir at 600-800 rpm for 0.5-1 hours to obtain pre-emulsion B; Step 4: Take 100-150 parts by weight of deionized water, add 5-10 parts of reactive emulsifier and 0.5-1 parts of aqueous initiator, stir evenly and heat to 70-90℃, add 5wt% of pre-emulsion A, react for 0.3-0.5 hours, then simultaneously add the remaining pre-emulsion A and 20 parts of initiator aqueous solution containing 1-1.5 parts of aqueous initiator, and continue adding for 2-3 hours; after the addition of pre-emulsion A is complete, continue adding pre-emulsion B and 20 parts of initiator aqueous solution containing 0.4-0.6 parts of aqueous initiator, and continue adding for 1-2 hours. After the addition is complete, continue to keep warm for 2-3 hours, cool to 20-30℃, add 25wt% ammonia to adjust pH to 7-9, filter through a 500-mesh filter to remove gel, and obtain water-based acrylic rust-preventive resin.

[0011] Preferably, the alkenyl aldehyde is one of acrolein, 2-methylacrolein, 2-ethylacrolein, 4-pentenal, and 10-undecenal; Preferably, the dihydrogen phosphate is one of ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate; Preferably, the reactive emulsifier is one of Shanghai Zhongcheng Chemical's ONIST NRS-10 and ONIST M-30S; Preferably, the short-chain mixed monomers are two or more of the following: vinyl acetate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. Preferably, the unsaturated carboxylic acid is one of methacrylic acid and acrylic acid; Preferably, the long-chain acrylate monomer is one of octadecyl acrylate and octadecyl methacrylate; Preferably, the cyclic acrylate monomer is one of isobornyl acrylate and isobornyl methacrylate; Preferably, the aqueous initiator is one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0012] The beneficial effects of this invention are as follows: a) The polymer chain of the waterborne acrylic rust-preventive resin of this invention contains pyrano[2,3-c]pyrazolyl groups, tertiary amines, phosphate groups, cyano groups, long-chain octadecyl groups, and isobornyl groups. Due to electrochemical action, metal substrates easily form galvanic cells in the presence of an aqueous system, causing surface corrosion. The pyrano[2,3-c]pyrazolyl groups can interact with unpaired electrons on the metal surface, reducing the electromotive force of the galvanic cell and fundamentally inhibiting flash rust. The nitrogen atom in the tertiary amine has a lone pair of electrons, which, in combination with the phosphate group, can form a highly stable chelate with multivalent metal ions and deposit on the metal surface. Simultaneously, the phosphate group can form hydrogen bonds with the hydroxyl groups on the metal surface, improving the adhesion of the paint film to the metal substrate, isolating oxygen and moisture from the metal surface, and providing long-term protection for the metal substrate. The cyano group can also have a certain complexing effect with multivalent metal ions, further improving the flash rust prevention performance and salt spray resistance of the waterborne acrylic rust-preventive resin on metal surfaces.

[0013] (b) The isoborneol group in the waterborne acrylic rust-preventive resin of this invention can improve the adhesion, water resistance, impact resistance, scratch resistance, and coating toughness of the waterborne acrylic rust-preventive resin to the substrate after drying, better isolating the easily corroded substrate from air, water, electrolytes, etc., and preventing further corrosion of the substrate. The octadecyl group in the waterborne acrylic rust-preventive resin of this invention can improve the hydrophobicity of the waterborne acrylic rust-preventive resin, delaying corrosion caused by minor defects during construction or long-term use of the paint film. The waterborne acrylic rust-preventive resin of this invention uses a reactive emulsifier, avoiding the migration of conventional emulsifiers during long-term use of the paint film, greatly improving the water resistance of the paint film, prolonging the protective effect of the paint film on the substrate, and achieving high gloss.

[0014] c) The waterborne acrylic rust-preventive resin of the present invention, as a film-forming substance of waterborne coatings, can achieve a good rust-preventive effect without the addition of rust-preventive pigments and fillers; it has good compatibility with conventional waterborne resins. In a formulation with conventional waterborne resin as the main film-forming substance, adding a portion of the waterborne acrylic rust-preventive resin of the present invention at any stage of paint mixing can significantly improve the early flash rust resistance and the later continuous rust prevention ability of conventional waterborne resins. Attached Figure Description

[0015] Figure 1 Infrared spectrum of the alkenylpyrano[2,3-c]pyrazole derivative E1 from Example 1; in the figure, 3200-3500 cm⁻¹ -1 The characteristic absorption peaks for the NH2 side chain and the NH bond of pyrazole are 2800-2950 cm⁻¹. -1 The characteristic absorption peaks for methyl and methylene groups are at 2205 cm⁻¹. -1 The characteristic absorption peaks of the CN group are 1400-1700 cm⁻¹. -1 The characteristic absorption peak of the pyran ring; Figure 2 Infrared spectrum of alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F1 in Example 1; in the figure, 3100-3500 cm⁻¹ -1 The broad peak is the characteristic absorption peak of hydroxyl groups, 2800-2950 cm⁻¹. -1 The characteristic absorption peaks for methyl and methylene groups are 950-1100 cm⁻¹. -1 The characteristic absorption peak of the PO bond in phosphate esters is 1150-1300 cm⁻¹. -1 The characteristic absorption peak of the P=O bond in phosphate esters; Figure 3 Infrared spectrum of waterborne acrylic rust-inhibiting resin G1 in Example 1; in the figure, 3100-3500 cm⁻¹ -1 The broad peak is the characteristic absorption peak of hydroxyl groups, 2800-2950 cm⁻¹. -1The characteristic absorption peaks for methyl and methylene groups are at 2205 cm⁻¹. -1 The characteristic absorption peak of the CN group is 1730 cm⁻¹. -1 The characteristic absorption peak of the C=O group of acrylate is 722 cm⁻¹. -1 The characteristic absorption peak is for straight-chain alkyl groups with n≥4.

[0016] Figure 4 The structural formulas of the alkenylpyrano[2,3-c]pyrazole derivatives E1-E5 in Examples 1-5.

[0017] Figure 5 The structural formulas of alkenylpyrano[2,3-c]pyrazole phosphate ammonium salts F1-F5 in Examples 1-5. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1

[0019] A method for preparing a water-based acrylic rust-inhibiting resin is described below: Step 1: At 25℃, add 130g of ethyl acetoacetate and 400g of ethanol to a reaction vessel and stir. Add 62.5g of 80wt% hydrazine hydrate solution dropwise, and stir for 1 hour after the addition is complete. Then, add 56g of acrolein and 68g of malononitrile in sequence, stir well, and then add 16g of the catalyst Purolite. ® CTA193Plus was reacted for 8 hours, and the catalyst was filtered off. 50g of ethanol was added to wash the catalyst, and the washings and filtrate were quickly poured into 4000g of deionized water, resulting in a large amount of precipitate. The precipitate was filtered and washed with 400g of 55wt% ethanol aqueous solution. The precipitate was then dried under vacuum at room temperature to obtain the alkenylpyrano[2,3-c]pyrazole derivative E1. The structural formula of E1 is shown below. Figure 4 As shown. The mass spectrometry data for E1 are as follows: MS (ESI) + m / z = 203.2([M+H]) + ), 225.2([M+Na] +The 1H NMR (400MHz, DMSO-d6) data for E1 are as follows: δ = 2.35 (s, 3H, CH3), 4.14 (d, H, CH), 5.01 (d, 2H, CH2), 5.71 (t, H, CH), 7.12 (s, 2H, NH2), 13.71 (s, H, NH). The purity of E1 was determined to be 96.62% by liquid chromatography. The yield of E1, based on ethyl acetoacetate, was 84.64%. The infrared spectrum of E1 is shown below. Figure 1 As shown.

[0020] Step 2: Add 126g of ammonium dihydrogen phosphate and 200g of deionized water to the reactor, heat to 75℃, adjust the pH to 6 with 25wt% ammonia, add 92.5g of epichlorohydrin dropwise, and maintain the temperature for 9 hours until the epichlorohydrin phase disappears. Cool down to 20℃; dissolve 68g of E1 in 500g of dichloromethane and add it to the reactor, add 10g of phase transfer catalyst PEG400, heat to 33℃, and slowly add 300g of 40wt% sodium hydroxide solution dropwise over 2 hours while stirring at 800rpm. Maintain the temperature for 6 hours; cool down to 20℃, allow to stand and separate into layers, and then add 1000g of the solution. After washing the organic phase with 1 mol / L hydrochloric acid, it was washed three times with 1000 g of deionized water. The aqueous phase was discarded, and 150 g of 25 wt% ammonia solution was added to the organic phase and stirred for 1 hour. The aqueous phase was then discarded, and dichloromethane was removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F1. The infrared spectrum of F1 is shown below. Figure 2 As shown. The structural formula of F1 is as follows. Figure 5 As shown. F1 1 ¹H NMR (400MHz, DMSO-d6) data are as follows: δ = 2.02 (d, 3H, OH), 2.70 (d, 4H, CH2), 2.79 (s, 3H, CH3), 3.21 (d, H, CH), 3.42–3.51 (dd, 2H, CH), 3.62–3.88 (dd, 8H, CH2), 4.14 (d, H, CH), 4.95 (d, 2H, CH2), 5.71 (t, H, CH).

[0021] Step 3: Dissolve 7g of reactive emulsifier ONIST NRS-10 in 210g of deionized water, and add dropwise a mixed monomer consisting of 50g methyl methacrylate, 65g methyl acrylate, 66g 2-ethylhexyl acrylate, 49g n-butyl acrylate and 5g methacrylic acid. Stir at 600rpm for 1 hour to obtain pre-emulsion A; Dissolve 10g of reactive emulsifier ONIST NRS-10 in 160g of deionized water, and add dropwise a mixed monomer consisting of 30g F1, 55g methyl methacrylate, 24g ethyl methacrylate, 61g 2-ethylhexyl acrylate, 8g acrylic acid, 18g octadecyl acrylate monomer and 25g isobornyl methacrylate. Stir at 600rpm for 1 hour to obtain pre-emulsion B.

[0022] Step 4: Take 150g of deionized water, add 10g of reactive emulsifier ONIST NRS-10 and 1g of potassium persulfate, stir well and heat to 70℃, add 5wt% of pre-emulsion A, react for 0.5 hours, then simultaneously add the remaining pre-emulsion A and 20g of aqueous solution containing 1g of potassium persulfate, continuing the dropwise addition for 3 hours; after the addition of pre-emulsion A is complete, continue adding pre-emulsion B and 20g of aqueous solution containing 0.4g of potassium persulfate, continuing the dropwise addition for 2 hours, and continue to keep warm for 3 hours. Cool down to 20℃, add 25wt% ammonia to adjust pH=7, filter through a 500-mesh filter to remove the gel, thus obtaining waterborne acrylic rust-inhibiting resin G1. The infrared spectrum of G1 is shown below. Figure 3 As shown. Example 2

[0023] A method for preparing a water-based acrylic rust-inhibiting resin is described below: Step 1: At 28℃, 130g of ethyl acetoacetate and 470g of ethanol were added to a reaction vessel and stirred. 65g of 80wt% hydrazine hydrate solution was added dropwise, and the mixture was stirred for 0.5 hours after the addition was complete. 72g of 2-methylpropenal and 70g of malononitrile were added sequentially, and after stirring until homogeneous, 15g of the catalyst Purolite was added. ® CTA193Plus was reacted for 9 hours, and the catalyst was filtered off. 80g of ethanol was added to wash the catalyst, and the washings and filtrate were quickly poured into 3500g of deionized water, resulting in a large amount of precipitate. The precipitate was filtered and washed with 400g of 55wt% ethanol aqueous solution. The precipitate was then dried under vacuum at room temperature to obtain the alkenylpyrano[2,3-c]pyrazole derivative E2. The structural formula of E2 is shown below. Figure 4 As shown. The mass spectrometry data for E2 are as follows: MS (ESI) + m / z = 217.2([M+H]) + ), 239.1([M+Na] + E2 1The ¹H NMR (400 MHz, DMSO-d6) data are as follows: δ = 1.71 (t, 3H, CH₃), 2.35 (s, 3H, CH₃), 4.13 (d, H, CH), 4.70 (s, 2H, CH₂), 7.12 (s, 2H, NH₂), 13.71 (s, H, NH). The purity of E₂ was determined to be 97.33% by liquid chromatography, and the yield of E₂ (based on ethyl acetoacetate) was 72.95%.

[0024] Step 2: Add 140g of ammonium dihydrogen phosphate and 250g of deionized water to the reactor, heat to 85℃, adjust the pH to 6.5 with 25wt% ammonia, add 92.5g of epichlorohydrin dropwise, and maintain the temperature for 6 hours until the epichlorohydrin phase disappears. Cool down to 30℃; dissolve 72.4g of E2 in 500g of dichloromethane and add it to the reactor, add 15g of phase transfer catalyst PEG400, heat to 38℃, and slowly add 320g of 40wt% sodium hydroxide solution dropwise over 1 hour while stirring at 800rpm. Maintain the temperature for 4 hours; cool down to 30℃, allow to stand and separate into layers, and then add 1000g of the solution. After washing the organic phase with 1 mol / L hydrochloric acid, the organic phase was washed three times with 1000 g of deionized water. The aqueous phase was discarded. 150 g of 25 wt% ammonia solution was added to the organic phase and stirred for 0.5 hours. The aqueous phase was discarded, and dichloromethane was removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F2. The structural formula of F2 is as follows: Figure 5 As shown. F2 1 ¹H NMR (400MHz, DMSO-d6) data are as follows: δ = 1.71 (s, 3H, CH3), 2.02 (d, 3H, OH), 2.70 (d, 4H, CH2), 2.79 (s, 3H, CH3), 3.21 (d, H, CH), 3.42-3.51 (dd, 2H, CH), 3.60-3.86 (dd, 8H, CH2), 4.14 (d, H, CH), 4.71 (d, 2H, CH2).

[0025] Step 3: Dissolve 5g of reactive emulsifier ONIST M-30S in 180g of deionized water, and add dropwise a mixed monomer consisting of 95g methyl methacrylate, 55g n-butyl acrylate, 50g 2-ethylhexyl methacrylate and 3g acrylic acid. Stir at 800rpm for 0.5 hours to obtain pre-emulsion A; Dissolve 15g of reactive emulsifier in 190g of deionized water, and add dropwise a mixed monomer consisting of 30g F2, 55g methyl methacrylate, 27g vinyl acetate, 48g ethyl acrylate, 30g n-butyl methacrylate, 10g methacrylic acid, 15g octadecyl methacrylate and 18g isobornyl acrylate. Stir at 800rpm for 0.5 hours to obtain pre-emulsion B; Step 4: Take 100g of deionized water, add 5g of reactive emulsifier ONIST M-30S and 0.5g of sodium persulfate, stir evenly and heat to 90℃, add 5wt% of pre-emulsion A, react for 0.3 hours, then simultaneously add the remaining pre-emulsion A and 20g of aqueous solution containing 1g of sodium persulfate, adding dropwise for 2 hours; after the addition of pre-emulsion A is complete, continue to add pre-emulsion B and 20g of aqueous solution containing 0.6g of sodium persulfate, adding dropwise for 1 hour, and continue to keep warm for 2 hours after the addition is complete, cool to 30℃, add 25wt% ammonia to adjust pH=9, filter through a 500-mesh filter to remove the gel, and obtain waterborne acrylic rust-preventive resin G2. Example 3

[0026] A method for preparing a water-based acrylic rust-inhibiting resin is described below: Step 1: At 30℃, 130g of ethyl acetoacetate and 500g of ethanol were added to a reaction vessel and stirred. 64g of 80wt% hydrazine hydrate solution was added dropwise, and the mixture was stirred for 0.5 hours after the addition was complete. 88g of 2-ethylpropenal and 72g of malononitrile were added sequentially, and after stirring until homogeneous, 17g of the catalyst Purolite was added. ® CTA193Plus was reacted for 10 hours, and the catalyst was filtered off. 60g of ethanol was added to wash the catalyst, and the washings and filtrate were quickly poured into 3000g of deionized water, resulting in a large amount of precipitate. The precipitate was filtered and washed with 400g of 55wt% ethanol aqueous solution. The precipitate was then dried under vacuum at room temperature to obtain the alkenylpyrano[2,3-c]pyrazole derivative E3. The structural formula of E3 is shown below. Figure 4 As shown. The mass spectrometry data for E3 are as follows: MS (ESI) + m / z = 231.0([M+H]) + ), 253.0([M+Na] + E3 1 The following ¹H NMR (400 MHz, DMSO-d6) data are as follows: δ = 1.06 (t, 3H, CH₃), 2.0 (dd, 2H, CH₂), 2.35 (s, 3H, CH₃), 4.13 (d, H, CH), 4.69 (s, 2H, CH₂), 7.12 (s, 2H, NH₂), 13.71 (s, H, NH). The purity of E₃ determined by liquid chromatography was 94.18%. The yield of E₃, based on ethyl acetoacetate, was 78.29%.

[0027] Step 2: Add 130g of ammonium dihydrogen phosphate and 230g of deionized water to the reactor, heat to 80℃, adjust the pH to 6.5 with 25wt% ammonia, add 92.5g of epichlorohydrin dropwise, and maintain the temperature for 6-9 hours until the epichlorohydrin phase disappears. Cool down to 25℃; dissolve 77g of E3 in 500g of dichloromethane and add it to the reactor, add 13g of phase transfer catalyst PEG400, heat to 36℃, and slowly add a solution containing 310g of 40wt% sodium hydroxide dropwise over 2 hours while stirring at 800rpm. Maintain the temperature for 5 hours; cool down to 25℃, allow to stand and separate into layers, and then add 1000g of the solution. After washing the organic phase with 1 mol / L hydrochloric acid, the organic phase was washed three times with 1000 g of deionized water. The aqueous phase was discarded. 150 g of 25 wt% ammonia was added to the organic phase and stirred for 1 hour. The aqueous phase was then discarded. Dichloromethane was removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F3. F3... 1 ¹H NMR (400MHz, DMSO-d6) data are as follows: δ = 1.06 (t, 3H, CH₃), 1.97 (dd, 2H, CH₂), 2.00 (d, 3H, OH), 2.70 (d, 4H, CH₂), 2.79 (s, 3H, CH₃), 3.21 (d, H, CH), 3.42–3.51 (dd, 2H, CH), 3.62–3.88 (dd, 8H, CH₂), 4.70 (d, 2H, CH₂). The structural formula of F₃ is as follows: Figure 5 As shown.

[0028] Step 3: Dissolve 6g of reactive emulsifier ONIST NRS-10 in 200g of deionized water, and add dropwise a mixed monomer consisting of 40g methyl acrylate, 70g methyl methacrylate, 35g ethyl acrylate, 45g n-butyl acrylate, 20g 2-ethylhexyl acrylate and 4g methacrylic acid. Stir at 700rpm for 1 hour to obtain pre-emulsion A; Dissolve 12g of reactive emulsifier ONIST NRS-10 in 180g of deionized water, and add dropwise a mixed monomer consisting of 30g F3, 57g methyl methacrylate, 23g ethyl acrylate, 30g vinyl acetate, 40g butyl methacrylate, 9g methacrylic acid, 17g octadecyl methacrylate and 21g isobornyl methacrylate. Stir at 700rpm for 1 hour to obtain pre-emulsion B; Step 4: Take 120g of deionized water, add 7g of reactive emulsifier ONIST NRS-10 and 0.8g of ammonium persulfate, stir evenly and heat to 80℃, add 5wt% of pre-emulsion A, react for 0.4 hours, then simultaneously add the remaining pre-emulsion A and 20g of aqueous solution containing 1.5g of ammonium persulfate, and continue adding for 2.5 hours; after the addition of pre-emulsion A is complete, continue adding pre-emulsion B and 20g of aqueous solution containing 0.4g of ammonium persulfate, and continue adding for 2 hours. After the addition is complete, continue to keep warm for 2.5 hours, cool to 25℃, add 25wt% ammonia water to adjust pH=8, filter through a 500-mesh filter to remove the gel, and obtain waterborne acrylic rust-preventive resin G3. Example 4

[0029] A method for preparing a water-based acrylic rust-inhibiting resin is described below: Step 1: At 25℃, add 130g of ethyl acetoacetate and 450g of ethanol to a reaction vessel and stir. Add 63g of 80wt% hydrazine hydrate solution dropwise, and stir for 1 hour after the addition is complete. Then, add 175g of 10-undecenal and 66g of malononitrile sequentially, stir well, and then add 13g of the catalyst Purolite. ® CTA193Plus was reacted for 12 hours, and the catalyst was filtered off. 70g of ethanol was added to wash the catalyst, and the washings and filtrate were quickly poured into 3400g of deionized water, resulting in a large amount of precipitate. The precipitate was filtered and washed with 400g of 55wt% ethanol aqueous solution. The precipitate was then dried under vacuum at room temperature to obtain the alkenylpyrano[2,3-c]pyrazole derivative E4. The structural formula of E4 is shown below. Figure 4 As shown. The mass spectrometry data for E4 are as follows: MS (ESI) + m / z = 315.0([M+H]) + ), 337.1([M+Na] + E4 1 The following ¹H NMR (400 MHz, DMSO-d6) data are as follows: δ = 1.30 (dd, 10H, CH₂), 1.62 (dd, 2H, CH₂), 1.96 (t, 2H, CH₂), 2.35 (s, 3H, CH₃), 3.45 (t, H, CH), 3.52 (dd, 3H, CH), 5.0 (t, 2H, CH₂), 5.70 (dd, H, CH), 7.12 (s, 2H, NH₂), 13.72 (s, H, NH). The purity of E₄ was determined to be 97.35% by liquid chromatography, and the yield of E₄ (based on ethyl acetoacetate) was 70.13%.

[0030] Step 2: Add 135g of ammonium dihydrogen phosphate and 240g of deionized water to the reactor, heat to 85℃, adjust the pH to 6 with 25wt% ammonia, add 92.5g of epichlorohydrin dropwise, maintain the temperature for 7 hours until the epichlorohydrin phase disappears, and cool to 25℃; dissolve 104g of E4 in 500g of dichloromethane and add it to the reactor, add 10g of phase transfer catalyst PEG400, heat to 35℃, and slowly add a solution containing 320g of 40wt% sodium hydroxide dropwise over 1.5 hours while stirring at 800rpm, maintain the temperature for 5 hours; cool to 30℃, allow to stand and separate into layers, and then add 1000g of the solution. After washing the organic phase with 1 mol / L hydrochloric acid, the organic phase was washed three times with 1000 g of deionized water. The aqueous phase was discarded. 150 g of 25 wt% ammonia solution was added to the organic phase and stirred for 0.5 hours. The aqueous phase was then discarded. Dichloromethane was removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F4. The structural formula of F4 is as follows: Figure 5 As shown. F4 1 ¹H NMR (400MHz, DMSO-d6) data are as follows: δ = 1.26-1.38 (dd, 12H, CH2), 1.62 (dd, 2H, CH2), 1.96-2.05 (dd, 5H, 3OH, 2CH2), 2.70 (d, 4H, CH2), 2.79 (s, 3H, CH3), 3.42-3.51 (dd, 4H, CH), 3.62-3.88 (dd, 8H, CH2), 5.0 (t, 2H, CH2).

[0031] Step 3: Dissolve 7g of reactive emulsifier ONIST M-30S in 180g of deionized water, and add dropwise a mixed monomer consisting of 80g of methyl methacrylate, 65g of n-butyl methacrylate, 65g of 2-ethylhexyl acrylate and 3g of acrylic acid. Stir at 600rpm for 1 hour to obtain pre-emulsion A; Dissolve 15g of reactive emulsifier ONIST M-30S in 190g of deionized water, and add dropwise a mixed monomer consisting of 30g of F4, 50g of methyl methacrylate, 55g of n-butyl methacrylate, 55g of 2-ethylhexyl methacrylate, 8g of acrylic acid, 17g of octadecyl acrylate and 25g of isobornyl methacrylate. Stir at 600rpm for 1 hour to obtain pre-emulsion B; Step 4: Take 140g of deionized water, add 10g of reactive emulsifier ONIST M-30S and 0.6g of ammonium persulfate, stir evenly and heat to 75℃, add 5wt% of pre-emulsion A, react for 0.5 hours, then simultaneously add the remaining pre-emulsion A and 20g of aqueous solution containing 1.2g of ammonium persulfate, and continue adding for 2 hours; after the addition of pre-emulsion A is complete, continue adding pre-emulsion B and 20g of aqueous solution containing 0.6g of ammonium persulfate, and continue adding for 2 hours. After the addition is complete, continue to keep warm for 3 hours, cool to 20-30℃, add 25wt% ammonia water to adjust pH=7.5, filter through a 500-mesh filter to remove the gel, and obtain waterborne acrylic rust-preventive resin G4. Example 5

[0032] A method for preparing a water-based acrylic rust-inhibiting resin is described below: Step 1: At 25℃, 130g of ethyl acetoacetate and 430g of ethanol were added to a reaction vessel and stirred. 64g of 80wt% hydrazine hydrate solution was added dropwise, and the mixture was stirred for 1 hour after the addition was complete. 84g of 4-pentenal and 66g of malononitrile were added sequentially, and after stirring until homogeneous, 13g of the catalyst Purolite was added. ® CTA193Plus was reacted for 8 hours, and the catalyst was filtered off. 50g of ethanol was added to wash the catalyst, and the washings and filtrate were quickly poured into 3700g of deionized water, resulting in a large amount of precipitate. The precipitate was filtered and washed with 400g of 55wt% ethanol aqueous solution. The precipitate was then dried under vacuum at room temperature to obtain the alkenylpyrano[2,3-c]pyrazole derivative E5. The structural formula of E5 is shown below. Figure 4 As shown. The mass spectrometry data for E5 are as follows: MS (ESI) + m / z = 231.2([M+H]) + ), 253.3([M+Na] + E5 1 ¹H NMR (400MHz, DMSO-d6) data are as follows: δ = 1.66 (dd, 2H, CH₂), 1.96 (dd, 2H, CH₂), 2.35 (s, 3H, CH₃), 3.44 (t, H, CH), 5.02 (d, 2H, CH₂), 5.70 (dd, H, CH), 7.12 (s, 2H, NH₂), 13.7 (s, H, NH). The purity of E₅ was determined to be 95.96% by liquid chromatography, and the yield of E₅ (based on ethyl acetoacetate) was 77.78%.

[0033] Step 2: Add 135g of ammonium dihydrogen phosphate and 240g of deionized water to the reactor, heat to 85℃, adjust the pH to 6 with 25wt% ammonia, add 92.5g of epichlorohydrin dropwise, and maintain the temperature for 7 hours until the epichlorohydrin phase disappears. Cool down to 25℃; dissolve 76g of E4 in 500g of dichloromethane and add it to the reactor, add 10g of phase transfer catalyst PEG400, heat to 35℃, and slowly add a solution containing 320g of 40wt% sodium hydroxide dropwise over 1.5 hours while stirring at 800rpm. Maintain the temperature for 5 hours; cool down to 30℃, allow to stand and separate into layers, and then add 1000g of the solution. After washing the organic phase with 1 mol / L hydrochloric acid, the organic phase was washed three times with 1000 g of deionized water. The aqueous phase was discarded. 150 g of 25 wt% ammonia solution was added to the organic phase and stirred for 0.5 hours. The aqueous phase was then discarded. Dichloromethane was removed by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt F5. The structural formula of F5 is as follows: Figure 5 As shown. F5 1 1H NMR (400MHz, DMSO-d6) data are as follows: δ = 1.66 (dd, 2H, CH2), 1.96-2.05 (dd, 5H, 3OH, 2CH2), 2.70 (d, 4H, CH2), 2.79 (s, 3H, CH3), 3.42-3.51 (dd, 4H, CH), 3.62-3.88 (dd, 8H, CH2), 5.0 (t, 2H, CH2), 5.71 (dd, H, CH).

[0034] Step 3: Dissolve 7g of reactive emulsifier ONIST M-30S in 180g of deionized water, and add dropwise a mixed monomer consisting of 30g methyl methacrylate, 50g methyl acrylate, 65g n-butyl methacrylate, 65g 2-ethylhexyl acrylate and 3g acrylic acid. Stir at 600rpm for 1 hour to obtain pre-emulsion A; Dissolve 15g of reactive emulsifier ONIST M-30S in 190g of deionized water, and add dropwise a mixed monomer consisting of 30g F4, 50g methyl methacrylate, 55g n-butyl methacrylate, 55g 2-ethylhexyl methacrylate, 8g acrylic acid, 17g octadecyl acrylate and 25g isobornyl methacrylate. Stir at 600rpm for 1 hour to obtain pre-emulsion B; Step 4: Take 140g of deionized water, add 10g of reactive emulsifier ONIST M-30S and 0.6g of ammonium persulfate, stir evenly and heat to 75℃, add 5wt% of pre-emulsion A, react for 0.5 hours, then simultaneously add the remaining pre-emulsion A and 20g of aqueous solution containing 1.2g of ammonium persulfate, adding dropwise for 2 hours; after the addition of pre-emulsion A is complete, continue to add pre-emulsion B and 20g of aqueous solution containing 0.6g of ammonium persulfate, adding dropwise for 2 hours, and continue to keep warm for 3 hours after the addition is complete, cool to 20-30℃, add 25wt% ammonia water to adjust pH=7.5, filter through a 500-mesh filter to remove gel, and obtain waterborne acrylic rust-preventive resin G5.

[0035] Application examples The waterborne acrylic rust-preventive resins G1-G5 of the present invention, the waterborne acrylic rust-preventive resin Wantipro® 0625 (G6) produced by Wanhua Chemical, the ordinary waterborne acrylic rust-preventive resin Archsol® 8086 (G7) produced by Wanhua Chemical, and the waterborne acrylic rust-preventive resins G1 and G7 of the present invention were mixed at a weight ratio of 1:2, and then the mixture was formulated into paint according to the formula in Table 1. The paints were named S1-S8 respectively, and corresponding performance tests were performed.

[0036] Table 1. Formulation of water-based anti-rust coatings

[0037] Water-based rust-preventive coatings S1-S8 were sprayed onto the surface of dry, clean carbon steel sheets. After natural drying, the flash rust on the carbon steel sheets was observed. The amount of flash rust on the carbon steel sheets with S1-S8 is shown in Table 2.

[0038] The adhesion test of the paint film on the carbon steel sheet was carried out according to "GB / T 9286-1998 Paints and varnishes - Cross - cut test for paints films", and the brief description is as follows: Use a special cross - cutter to cut through the paint film along one direction, ensuring that the carbon steel is exposed by the scratches. Then use the cross - cutter to cut through the paint film forcefully along a direction at 90° to the original cutting line, forming a certain number of small square grid patterns on the paint film. Use a soft brush to remove the debris on the surface, cover the grid pattern with adhesive tape, and rub the adhesive tape with the fingertip forcefully to make the adhesive tape fully contact the grid pattern. Then peel off the adhesive tape as smoothly as possible at an angle close to 60°. Observe the peeling situation of the paint film in the grid pattern. Adhesion grade evaluation criteria: Grade 0 - The cutting edge is completely smooth and none of the grids peel off; Grade 1 - There is a little coating peeling at the intersection of the cuts, but the affected cross - cut area is not significantly greater than 5%; Grade 2 - There is coating peeling at the intersection of the cuts and / or along the cut edge, and the affected cross - cut area is significantly greater than 5%, but not significantly greater than 15%; Grade 3 - The coating partially or completely peels off along the cutting edge in large fragments, and / or partially or completely flakes off at different parts, and the affected cross - cut area is significantly greater than 15%, but not significantly greater than 35%; Grade 4 - The coating peels off in large fragments along the cutting surface, and / or some squares partially or completely peel off, and the affected cross - cut area is significantly greater than 35%, but not significantly greater than 65%; Grade 5 - The degree of peeling exceeds Grade 4. The adhesion effect ratings of S1 - S8 are shown in Table 2.

[0039] Place the carbon steel sheet with the completely dried paint film in a salt spray chamber, use neutral NaCl solution as the salt spray, and according to the method specified in "GB / T 10125-2012 Corrosion tests in artificial atmospheres - Salt spray tests", the test period is 480 hours. After the salt spray test, according to "GB / T 6461-2002 Rating of specimens and test pieces of metallic and other inorganic coatings on metallic substrates after corrosion tests", rate the salt spray resistance effects of P1 and P5. Based on the defect area A, rate the defect - free test pieces as Grade 10, 0 < A ≤ 0.1% as Grade 9, 0.1% < A ≤ 0.25% as Grade 8, 0.25% < A ≤ 0.5% as Grade 7, 0.5% < A ≤ 1% as Grade 6, 1% < A ≤ 2.5% as Grade 5, 2.5% < A ≤ 5% as Grade 4, 5% < A ≤ 10% as Grade 3, 10% < A ≤ 25% as Grade 2, 25% < A ≤ 50% as Grade 1, A > 50% as Grade 0. The salt spray resistance effects ratings of S1 - S8 are shown in Table 2.

[0040] Scrape a 250 - μm wet film of S1 - S8 on black and white cardboard. After it is completely dried, conduct glossiness tests on the paint film according to "GB / T 9754-2007 Paints and varnishes - Determination of specular gloss at 20°, 60° and 85° of paint films without metallic pigments". The test results are shown in Table 2.

[0041] Table 2. Performance Test Comparison of Waterborne Coatings S1-S8

[0042] Table 2 shows that the waterborne rust-preventive coatings prepared from the waterborne acrylic ester rust-preventive resin of this invention exhibit adhesion grades of 0 and 1 on carbon steel sheets, significantly better than ordinary waterborne coatings. Their flash rust resistance and salt spray resistance ratings are also significantly superior to ordinary waterborne coatings. Furthermore, the waterborne coatings formulated with the waterborne acrylic ester G1 of this invention and ordinary waterborne resin at a weight ratio of 1:2 also show a significant improvement in adhesion. This indicates that the waterborne acrylic ester rust-preventive resin of this invention has excellent protective capabilities for metal substrates. When mixed with conventional waterborne resins, it can also significantly improve the initial flash rust resistance and the sustained rust prevention capability of conventional waterborne resins. From a gloss perspective, the waterborne acrylic ester rust-preventive resin of this invention has a high gloss, making it suitable for high-gloss rust-preventive applications.

[0043] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a water-based acrylic rust-inhibiting resin, characterized in that: Includes the following steps: Step 1: By weight, at 25-30℃, add 130 parts of ethyl acetoacetate and 400-500 parts of ethanol to a reaction vessel and stir. Add 62.5-65 parts of 80wt% hydrazine hydrate solution dropwise, stirring for 0.5-1 hour after the addition is complete. Then, add 56-175 parts of alkenyl aldehyde and 66-72 parts of malononitrile sequentially, stirring until homogeneous. Finally, add 13-17 parts of the catalyst Purolite. ® CTA193Plus, react for 8-12 hours, filter out the catalyst; add 50-80 parts of ethanol to wash the catalyst, and quickly pour the washing liquid and filtrate into 3000-4000 parts of deionized water to obtain a large amount of precipitate. Filter and wash the precipitate with 400 parts of 55wt% ethanol aqueous solution, and vacuum dry the precipitate at room temperature to obtain alkenylpyrano[2,3-c]pyrazole derivative. Step 2: By weight, add 126-140 parts of dihydrogen phosphate and 200-250 parts of deionized water to the reactor, heat to 75-85℃, adjust the pH to 6-6.5 with 25wt% ammonia, add 92.5 parts of epichlorohydrin dropwise, maintain the temperature for 6-9 hours until the epichlorohydrin phase disappears, and cool to 20-30℃; then dissolve 68-104 parts of the alkenylpyrano[2,3-c]pyrazole derivative obtained in Step 1 in 500 parts of dichloromethane, and continue to add it to the reactor, along with 10-15 parts of the phase transfer catalyst PEG400. Heat the solution to 33-38℃ and slowly add 300-320 parts of 40wt% sodium hydroxide solution dropwise over 1-2 hours while stirring at 800rpm. Keep the solution warm for 4-6 hours. Cool the solution to 20-30℃, allow it to stand and separate into layers. Wash the organic phase with 1000 parts of 1mol / L hydrochloric acid, then wash the organic phase three times with 1000 parts of deionized water. Discard the aqueous phase. Add 150 parts of 25wt% ammonia water to the organic phase and stir for 0.5-1 hour. Discard the aqueous phase. Remove dichloromethane by vacuum distillation at room temperature to obtain alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt. Step 3: Dissolve 5-7 parts by weight of reactive emulsifier in 180-210 parts of deionized water, and add dropwise a mixed monomer consisting of 200-230 parts of short-chain mixed monomers and 3-5 parts of unsaturated carboxylic acids. Stir at 600-800 rpm for 0.5-1 hours to obtain pre-emulsion A; Dissolve 10-15 parts by weight of reactive emulsifier in 160-190 parts of deionized water, and add dropwise a mixed monomer consisting of 30 parts of alkenylpyrano[2,3-c]pyrazole phosphate ammonium salt, 140-160 parts of short-chain mixed monomers, 8-10 parts of unsaturated carboxylic acids, 15-18 parts of long-chain acrylate monomers, and 18-25 parts of cyclic acrylate monomers. Stir at 600-800 rpm for 0.5-1 hours to obtain pre-emulsion B; Step 4: Take 100-150 parts by weight of deionized water, add 5-10 parts of reactive emulsifier and 0.5-1 parts of aqueous initiator, stir evenly and heat to 70-90℃, add 5wt% of pre-emulsion A, react for 0.3-0.5 hours, then simultaneously add the remaining pre-emulsion A and 20 parts of initiator aqueous solution containing 1-1.5 parts of aqueous initiator, and continue adding for 2-3 hours; after the addition of pre-emulsion A is complete, continue adding pre-emulsion B and 20 parts of initiator aqueous solution containing 0.4-0.6 parts of aqueous initiator, and continue adding for 1-2 hours. After the addition is complete, continue to keep warm for 2-3 hours, cool to 20-30℃, add 25wt% ammonia to adjust pH to 7-9, filter through a 500-mesh filter to remove gel, and obtain water-based acrylic rust-preventive resin.

2. The preparation method according to claim 1, characterized in that: The alkenyl aldehyde is one of acrolein, 2-methylacrolein, 2-ethylacrolein, 4-pentenal, and 10-undecenal.

3. The preparation method according to claim 1, characterized in that: The dihydrogen phosphate is one of ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate.

4. The preparation method according to claim 1, characterized in that: The reactive emulsifier is one of ONIST NRS-10 and ONIST M-30S from Shanghai Zhongcheng Chemical Co., Ltd.

5. The preparation method according to claim 1, characterized in that: The short-chain mixed monomers are two or more of the following: vinyl acetate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate; the unsaturated carboxylic acid is one of methacrylic acid and acrylic acid.

6. The preparation method according to claim 1, characterized in that: The long-chain acrylate monomer is one of octadecyl acrylate and octadecyl methacrylate.

7. The preparation method according to claim 1, characterized in that: The cyclic acrylate monomer is one of isoborneol acrylate and isoborneol methacrylate.

8. The preparation method according to claim 1, characterized in that: The aqueous initiator is one of potassium persulfate, sodium persulfate, and ammonium persulfate.

9. The waterborne acrylic rust-preventive resin prepared by the preparation method according to claim 1.

10. The application of the waterborne acrylic rust-inhibiting resin according to claim 9, characterized in that: The water-based acrylic rust-preventive resin is used as a film-forming agent to protect the surface of metal substrates, or it can be used in combination with conventional water-based resins to prevent the metal substrates from rusting.

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