Organic modified phosphating on-rust coating primer and preparation method thereof

Abstract

The invention belongs to the technical field of coating compositions, and particularly relates to an organic modified phosphating on-rust coating primer and a preparation method thereof. The organic modified phosphating rusty coating primer is prepared from the following components: 3-10% of organic modified phosphating rust removal and prevention liquid; 50-70% of a water-based acrylic emulsion; 3-3.6% of a coalescing agent; 0.5%-1.2% of a functional auxiliary agent; 7-10% of a pigment; 8-11% of a filler; 0.4 to 0.8 percent of a thickening agent; 1-1.5% of an anti-settling agent; and the balance of deionized water A. The preparation method comprises the following steps: uniformly mixing the deionized water A and the functional auxiliary agent, sequentially adding the pigment, the filler, the organic modified phosphating rust removal and rust prevention liquid, the water-based acrylic emulsion, the thickening agent, the anti-settling agent and the coalescing agent, and uniformly mixing to prepare the organic modified phosphating rusty coating primer. According to the invention, the phosphating rust-removing and rust-preventing liquid is organically modified, so that the problems of poor treatment effect on a complex rust layer, poor paint film appearance, insufficient adhesive force and insufficient impact resistance of the existing rusty coating are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coating compositions, and in particular relates to an organic modified phosphating rust-bearing coating primer and a preparation method thereof. Background Art

[0002] Metal corrosion not only causes huge economic losses, but also consumes a lot of resources and aggravates environmental pollution. In order to reduce corrosion losses, people have taken many measures. So far, the most commonly used and economical method is to apply anti-corrosion paint on the metal surface to form a paint film to slow down the corrosion of the metal. In order to obtain excellent comprehensive performance, pretreatment before painting, especially rust removal on the surface of steel structures, is very important. Otherwise, the residual rust will generate internal stress in the coating due to the volume expansion effect during the formation of trivalent iron hydrate, which will cause the paint film to bubble and fall off, reducing the long-term protective performance of the paint film.

[0003] At present, the domestic main method of rust removal is manual grinding, sandblasting, shot blasting or pickling, etc., and then the coating process is adopted. This type of coating process has the problems of large investment in mechanical equipment, serious noise and dust pollution, high labor cost and unsatisfactory construction effect in the dead corners of structural parts. Sometimes, due to the complex geometric structure and special environmental requirements, it is difficult to fully remove the rust of steel structures. At this time, rust-resistant coatings are needed. Rust-resistant coatings refer to coatings that can convert the rust layer into a stable substance through chemical and physical methods and closely combine with the rust layer to prevent further development of rust, play an anti-corrosion and protect steel. Rust-resistant coatings can be divided into water-based rust-resistant coatings, solvent-based rust-resistant coatings, etc.; among them, water-based rust-resistant coatings can be directly coated with rust and water, which is convenient to use and simple and easy to operate; but it also has many disadvantages, such as relatively weak adhesion and impact resistance, poor appearance of the paint film, and is mostly used for rust prevention, and the effect of rust removal is insufficient.

[0004] Chinese patent CN104140739A discloses a method for preparing a water-based epoxy anti-rust primer for steel structures, comprising component A and component B. Component A comprises a water-based epoxy curing agent, iron oxide red powder, corrosion inhibitor, composite phosphorus titanium powder, ultrafine aluminum hydroxide, environmentally friendly zinc phosphate, precipitated barium sulfate, additives, hydroxyethyl cellulose, a cosolvent, and deionized water; component B comprises a water-soluble epoxy resin, a neutralizer, and deionized distilled water.

[0005] In this patent, composite titanium phosphorus powder and environmentally friendly zinc phosphate are rust inhibitors, whose main function is to react with rust to form a stable iron phosphate passivation film to prevent the spread of rust. However, the lack of rust removers such as phosphoric acid and tannic acid makes the rust-proof primer described in this patent have poor adaptability to complex rust layers such as thick rust and stratified rust (loose outer layer and dense inner layer).

[0006] Chinese patent CN105038423A discloses a rust-removing and rust-preventing colored heavy anticorrosive single-component primer and its production process, wherein the primer comprises the following components by weight: 5-20 parts of deionized water, 20-25 parts of rust-removing and rust-preventing agent, 2-8 parts of film-forming aid, 2-4 parts of antifreeze agent, 0.1-0.2 parts of thickener, 3-10 parts of color paste, 0.3-1 parts of defoamer, 40-70 parts of film-forming substance, 3-5 parts of adhesion modifier, and 0.3-0.6 parts of substrate wetting agent. The rust-removing and rust-preventing agent used is 1318 steel protective agent or KX-123 steel protective agent. In this patent, 1318 / KX-123 is mainly composed of corrosion inhibitors and film-forming agents, and lacks strong acid rust removal ingredients. Rust is mainly removed by physical encapsulation rather than chemical dissolution. The treatment effect on complex rust layers is poor. Therefore, loose floating rust and old paint films need to be manually removed before construction, and firmly attached rust marks still need to be retained, which increases the complexity of construction; and complex rust layers need to be painted multiple times, which reduces construction efficiency. Summary of the invention

[0007] The purpose of the present invention is to provide an organic modified phosphating rust coating primer to solve the problems that the current rust coating has a poor treatment effect on complex rust layers, as well as poor paint film appearance, insufficient adhesion and impact resistance; the present invention also provides a preparation method.

[0008] To achieve the above object, the technical solution adopted by the present invention is: The organic modified phosphating rust-proof coating primer of the present invention is made of the following components in terms of mass percentage: Organic modified phosphating rust removal and anti-rust liquid 3~10%; Water-based acrylic emulsion 50~70%; Film-forming aid 3~3.6%; Functional additives 0.5~1.2%; Pigment 7~10%; Filler 8~11%; Thickener 0.4~0.8%; Anti-settling agent 1~1.5%; Deionized water A balance; The organic modified phosphating rust removing and preventing liquid is prepared from sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid, potassium molybdate, organic sulfonate and deionized water B.

[0009] in: The preparation steps of the organic modified phosphating rust removing and rust preventing liquid are as follows: First, sodium dihydrogen phosphate and potassium dihydrogen phosphate are added to deionized water B, and phosphoric acid is added and mixed evenly to obtain a phosphating rust-removing and rust-preventing liquid; potassium molybdate and organic sulfonate are added and stirred to dissolve to obtain an organic modified phosphating rust-removing and rust-preventing liquid; wherein the organic sulfonate is sodium nitrobenzene sulfonate or potassium nitrobenzene sulfonate.

[0010] The mass ratio of the potassium molybdate, the organic sulfonate and the phosphating rust removing and anti-rust liquid is (3-5): (0.2-0.4):100.

[0011] The mass ratio of the sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid and deionized water B is 2:2:0.85:(5-10).

[0012] The functional additive is composed of a wetting dispersant and a defoaming agent. The wetting dispersant is polyether polyol, and the defoaming agent is polyether modified silicone. The mass ratio of the wetting dispersant to the defoaming agent is (3-5):1.

[0013] The filler is composed of titanium dioxide and barium sulfate; the mass ratio of titanium dioxide to barium sulfate is 1:(1-2).

[0014] The pigment is ferric oxide, the film-forming aid is alcohol ester dodecahydrate, the thickener is hydroxyethyl cellulose, and the anti-settling agent is fumed silica.

[0015] The method for preparing the organic modified phosphating rust-resistant coating primer of the present invention comprises the following steps: (1) Stir deionized water A and functional additives evenly; (2) Add pigment, filler and organic modified phosphating rust removal and rust prevention liquid and stir evenly to obtain slurry; (3) Continue to add water-based acrylic emulsion to the slurry and stir evenly; (4) Finally, add thickener, anti-settling agent and film-forming aid and stir until evenly mixed to obtain organic modified phosphating rust-resistant coating primer.

[0016] in: In the step (1), the stirring time is 10-20 min and the stirring rate is 100-200 r / min; in the step (2), the stirring time is 10-20 min and the stirring rate is 800-1000 r / min.

[0017] In the step (3), the stirring time is 10 to 15 minutes, and the stirring rate is 300 to 400 r / min; in the step (4), the stirring time is 10 to 15 minutes, and the stirring rate is 200 to 300 r / min.

[0018] The beneficial effects of the present invention are as follows: (1) The raw materials used in the present invention are cheap, have little odor, are pollution-free, are safe and environmentally friendly during storage, transportation and use, have good application performance, are simple in construction process, and construction tools can be directly washed with water. Compared with other conventional system coatings, the supporting performance is excellent.

[0019] (2) The main innovation of the present invention lies in the composition and application of the organic modified phosphating rust removal and rust prevention liquid: Since some complex rust layers include a dense inner rust layer (γ-FeOOH) and a loose outer rust layer (α-FeOOH), the transformation products of traditional rust inhibitors and rust removers in the outer layer (such as iron phosphate complexes) will further hinder their formation in the inner layer, forming closed micro-areas, making it difficult to completely remove the dense rust layer in the inner layer.

[0020] The present invention uses a ternary system of phosphate-molybdate-sulfonate to achieve synergistic effects: sodium dihydrogen phosphate and potassium dihydrogen phosphate provide pH buffering capacity for phosphoric acid to avoid local overcorrosion caused by the strong acidity of single phosphoric acid. The three work together to transform the loose rust layer into a porous mesh-like iron phosphate passivation film (FePO 4 ·2H 2 O), can cover the micro cracks and other macro defects of the rust layer; the sulfonic acid group in the organic sulfonate is adsorbed on the surface of the iron phosphate complex, reducing the interfacial tension and enhancing the permeability of potassium molybdate, thereby effectively penetrating into the dense rust layer of the inner layer; at this time, MoO 4 2- It forms an iron molybdate passivation film with γ-FeOOH. Iron molybdate is a dense nanocrystal that can fill the micron-level pores in the rust layer to form a double-layer passivation film.

[0021] As a surfactant, organic sulfonate can form a sulfonic acid-carboxylic acid composite structure through the sulfonic acid group and the carboxyl group of the aqueous acrylic emulsion, improve the wettability and elasticity of the aqueous acrylic emulsion on the rust layer surface, penetrate into the network structure of the iron phosphate complex, form an elastic transition layer between the two passivation films, absorb the thermal stress caused by the difference in thermal expansion coefficients of the two passivation films, maintain the stability of the film layer, and prevent the film layer from falling off. Therefore, when the organic modified phosphating rust-bearing coating primer in the present invention is used, there is no need to perform rust removal operations, and it can be directly applied to the complex rust layer, reducing the complexity of the construction operation. In addition, because organic sulfonates can enhance the permeability of potassium molybdate. Therefore, the present invention is suitable for 20~120μm rust layers, with a wider application scenario, without the need for brushing, drying (i.e., waiting for the rust remover to penetrate into the dense rust layer for reaction), and then brushing, which improves the construction efficiency.

[0022] (3) The present invention adds organic sulfonates to the phosphating rust-removing and rust-preventing liquid. This is because phosphoric acid is acidic and will produce hydrogen when reacting with the rust layer. The overflow of hydrogen will produce a large number of pores on the surface of the iron phosphate passivation film, destroying the continuity and density of the iron phosphate passivation film, making it unable to effectively isolate the corrosive environment. The iron phosphate passivation film formed by using only phosphoric acid cannot meet the rust prevention requirements of steel structures. Therefore, the present invention adds organic sulfonates to the phosphating rust-removing and rust-preventing liquid. Compared with other commonly used oxidants such as sodium nitrate and sodium nitrite; sodium nitrate has too strong an oxidizing property, NO 3 - Fe 2+ Rapidly oxidized to Fe 3+ , resulting in FePO 4 The deposition is too fast, and the structure of the iron phosphate passivation film is too loose; NO in sodium nitrite 2 - The oxidizing property is insufficient and hydrogen cannot be effectively converted; the organic sulfonate in the present invention has moderate oxidizing property and has a corrosion inhibition effect, which can convert hydrogen into water, reduce the generation of bubbles, help to ensure the integrity of the passivation film, and reduce the film brittleness.

[0023] (4) In addition, the stability of the sodium nitrobenzene sulfonate or potassium nitrobenzene sulfonate used in the present invention is better than that of sodium nitrite. In addition, sodium nitrite is not environmentally friendly, is a carcinogen, and has no dispersing effect. The organic sulfonate used in the present invention is not only environmentally friendly, but also has the functions of dispersing and guiding adsorption. When used in combination with sodium dihydrogen phosphate or potassium dihydrogen phosphate, it can refine the film-forming grains, make the film more dense, and improve the uniformity and fastness of the passivation film. This is because the H 2 PO 4 - with Fe 2+ / Fe 3+ Formation of soluble complexes (such as [Fe(H 2 PO 4 ) 3 ] - ), delaying FePO 4 The direct precipitation of FePO makes a large number of tiny nuclei evenly distributed on the metal surface; the sulfonic acid group can selectively adsorb on the high-energy sites on the metal surface (such as grain boundaries and defects), inducing 4 Nucleation is preferentially formed in these areas, further increasing the nucleus density and promoting grain refinement during grain growth.

[0024] (5) The organic sulfonate used in the present invention has good compatibility with the aqueous acrylic emulsion. The sulfonic acid group is combined with the polar group (such as the carboxylic acid group) of the aqueous acrylic emulsion through hydrogen bonding or electrostatic interaction, ensuring that the wetting dispersant and the aqueous acrylic emulsion are evenly mixed to avoid phase separation. The benzene ring structure is compatible with the hydrophobic chain segment in the emulsion to form a stable interface layer, which improves the flexibility of the film and the adhesion of the aqueous acrylic emulsion, and promotes the organic film layer (aqueous acrylic emulsion) and the double-layer passivation film to form a dense protective coating, thereby protecting the steel structure. DETAILED DESCRIPTION

[0025] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0026] Prepare raw materials The wetting and dispersing agents used in the following examples and comparative examples were provided by Tianjin Saifei Chemical, with the brand name Ketuole ® 910; defoamer provided by Tianjin Saifei, brand name Ketuole ® DF-520; water-based acrylic emulsion provided by BASF, brand name AcronalPRO 763.

[0027] Example 1 Preparation of organic modified phosphating rust removal and anti-rust liquid: According to the mass ratio of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid and deionized water B of 2:2:0.85:5, weigh sodium dihydrogen phosphate and potassium dihydrogen phosphate and add them to deionized water B, stir evenly, add phosphoric acid, stir at a speed of 100 r / min for 3 minutes, and prepare 300 kg of phosphating rust removal and rust preventive liquid.

[0028] Take 150 kg of phosphating rust removing and rust preventing liquid, continue to add 4.5 kg of potassium molybdate and 0.3 kg of sodium nitrobenzene sulfonate, stir and dissolve, and obtain an organic modified phosphating rust removing and rust preventing liquid.

[0029] Preparation of organic modified phosphating rust-proof coating primer: (1) Take 5 kg of deionized water A, 3 kg of wetting and dispersing agent polyether polyol, and 1 kg of defoaming agent polyether modified silicone and add them into a high-speed mixer. Stir for 20 min at a stirring rate of 100 r / min.

[0030] (2) Add 35 kg of ferric oxide, 25 kg of barium sulfate, 25 kg of titanium dioxide, and 25 kg of organic modified phosphating rust remover and preventer, and stir for 10 min at a stirring rate of 800 r / min to obtain a uniformly dispersed slurry.

[0031] (3) Then add 350 kg of water-based acrylic emulsion into the slurry and stir for 10 min at a stirring rate of 300 r / min to mix evenly.

[0032] (4) Add 3 kg of hydroxyethyl cellulose, 5 kg of fumed silica, and 18 kg of alcohol ester twelve, stir for 15 minutes at a stirring rate of 300 r / min, add deionized water A, mix evenly to obtain 500 kg of organic modified phosphating rust-proof coating primer. The proportion of organic modified phosphating rust removal and rust prevention liquid in the organic modified phosphating rust-proof coating primer is 5%.

[0033] Example 2 Preparation of organic modified phosphating rust removal and anti-rust liquid: According to the mass ratio of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid and deionized water B of 2:2:0.85:7, weigh sodium dihydrogen phosphate and potassium dihydrogen phosphate and add them to deionized water B, stir evenly, add phosphoric acid, stir at a speed of 120r / min for 5min, and prepare 300kg phosphating rust removing and rust preventive liquid.

[0034] Take 150 kg of phosphating rust-proof and rust-removing liquid, continue to add 7.5 kg of potassium molybdate and 0.6 kg of potassium nitrobenzene sulfonate, stir and dissolve, and obtain an organic modified phosphating rust-proof and rust-removing liquid.

[0035] Preparation of organic modified phosphating rust-proof coating primer: (1) Take 30 kg of deionized water A, 4 kg of wetting and dispersing agent polyether polyol, and 1 kg of defoaming agent polyether modified silicone and add them into a high-speed mixer. Stir for 10 min at a stirring rate of 200 r / min.

[0036] (2) Add 38 kg of ferric oxide, 33 kg of barium sulfate, 22 kg of titanium dioxide, and 40 kg of organic modified phosphating rust remover and preventer, and stir for 20 min at a stirring rate of 1000 r / min to obtain a uniformly dispersed slurry.

[0037] (3) Add 300 kg of water-based acrylic emulsion into the slurry and stir for 15 min at a stirring rate of 400 r / min until it is evenly mixed.

[0038] (4) Add 4 kg of hydroxyethyl cellulose, 5.5 kg of fumed silica, and 17.5 kg of alcohol ester twelve, and stir for 12 min at a stirring rate of 230 r / min. Add deionized water A, and mix evenly to obtain 500 kg of organic modified phosphating rust-proof coating primer. The proportion of organic modified phosphating rust removal and rust prevention liquid in the organic modified phosphating rust-proof coating primer is 8%.

[0039] Example 3 Preparation of organic modified phosphating rust removal and anti-rust liquid: According to the mass ratio of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid and deionized water B of 2:2:0.85:10, add sodium dihydrogen phosphate and potassium dihydrogen phosphate to deionized water B, stir evenly, add phosphoric acid, stir at a speed of 150r / min for 4 minutes, and prepare 300kg phosphating rust removal and rust preventive liquid.

[0040] Take 150 kg of phosphating rust removing and rust preventing liquid, continue to add 6 kg of potassium molybdate and 0.5 kg of potassium nitrobenzene sulfonate, stir and dissolve, and prepare an organic modified phosphating rust removing and rust preventing liquid.

[0041] Preparation of organic modified phosphating rust-proof coating primer: (1) Take 75 kg of deionized water A, 5 kg of wetting and dispersing agent polyether polyol, and 1 kg of defoaming agent polyether modified silicone and add them into a high-speed mixer. Stir for 13 min at a stirring rate of 160 r / min.

[0042] (2) Add 50 kg of ferric oxide, 26 kg of barium sulfate, 14 kg of titanium dioxide, and 50 kg of organic modified phosphating rust remover and preventer, and stir for 16 minutes at a stirring rate of 890 r / min to obtain a uniformly dispersed slurry.

[0043] (3) Add 250 kg of water-based acrylic emulsion into the slurry and stir for 12 min at a stirring rate of 320 r / min until mixed evenly.

[0044] (4) Add 2 kg of hydroxyethyl cellulose, 7.5 kg of fumed silica, and 15 kg of alcohol ester twelve, stir for 11 minutes at a stirring rate of 200 r / min, add deionized water A, and mix evenly to obtain 500 kg of organic modified phosphating rust-proof coating primer. The proportion of organic modified phosphating rust removal and rust prevention liquid in the organic modified phosphating rust-proof coating primer is 10%.

[0045] Example 4 In step (2), 15 kg of organic modified phosphating rust removing and rust preventing liquid is added, that is, the proportion of organic modified phosphating rust removing and rust preventing liquid is 3%, and the remaining steps and raw materials are the same as those in Example 2.

[0046] Comparative Example 1 Without adding organic sulfonate, the remaining steps and raw materials were the same as those in Example 1 to prepare a primer for coating.

[0047] Comparative Example 2 Sodium nitrite was used instead of organic sulfonate, and the remaining steps and raw materials were the same as those in Example 1 to prepare a primer for coating.

[0048] Comparative Example 3 Without adding organic modified phosphating rust removing and preventing liquid, the remaining steps and raw materials are the same as those in Example 1 to prepare a primer for coating.

[0049] Comparative Example 4 Without adding sodium dihydrogen phosphate and potassium dihydrogen phosphate, the remaining steps and raw materials are the same as those in Example 1 to prepare a primer for coating.

[0050] Comparative Example 5 Without adding potassium molybdate, the remaining steps and raw materials were the same as those in Example 1 to prepare a primer for coating.

[0051] Implementation effect evaluation The coating primer test panels prepared in each embodiment and comparative example were made and then subjected to performance testing. The testing standards and parameters were as follows: The pull-off adhesion test is in accordance with GB / T 5210-2006 "Pull-off adhesion test for paints and varnishes", the test panel is a rusty steel plate, and the preparation method is made according to Method 1 in Appendix A of HG / T 5173-201 "Film thickness of water-based primer for rusty coatings"; the impact test is in accordance with GB / T 1732-2020 "Determination of impact resistance of paint film", the test panel is a tinplate, and the film thickness is 23±3μm; the bending test adopts GB / T 6742-2007 "Bending test for paints and varnishes (cylindrical shaft)"; the cross-cut test adopts GB / T 9286-2021 "Cross-cut test for paints and varnishes"; the VOC content adopts GB / T 23986.2-2023 "Determination of volatile organic compound (VOC) and / or semi-volatile organic compound (SVOC) content of paints and varnishes Part 2: Gas chromatography"; freeze-thaw resistance adopts GB / T 9268-2008 "Determination of freeze-thaw resistance of latex paint"; primer is applied on steel plates with an original substrate thickness of 5mm and a rust layer of 60-120μm, and the appearance of the paint film is compared after 4h and 48h. The results are shown in Table 1.

[0052]

[0053] As can be seen from Table 1, in Comparative Example 1, no sodium nitrobenzene sulfonate was added, and the test results of adhesion, impact resistance, paint film appearance, etc. were obviously not as good as those of the embodiments of the present invention. The main reasons are that sodium nitrobenzene sulfonate and potassium nitrobenzene sulfonate have a dispersing effect, which can refine the phosphating film and make the film formation more uniform. Second, sodium nitrobenzene sulfonate and potassium nitrobenzene sulfonate have an oxidizing effect. When the phosphating solution contacts the iron under the rust layer, hydrogen will be generated, and sodium nitrobenzene sulfonate will oxidize it into water, reducing the generation of bubbles and improving the integrity of the paint film. Therefore, the adhesion, impact resistance, scratch resistance, and toughness are relatively good.

[0054] Comparative Example 2 uses conventional oxidant sodium nitrite to replace the organic sulfonate in Example 1 of the present invention, and the test results of adhesion, impact resistance, cross-cutting test, paint film appearance, etc. are obviously not as good as those of the present invention. Nitrite (such as sodium nitrite) is unstable in high temperature or acidic environment, and is easily decomposed into nitric oxide and nitrogen dioxide gas, which produces bubbles, resulting in uneven film formation. Bubbles also cause pores in the paint film, which cause the paint film to be poorly applied, poor adhesion, poor impact resistance, not durable, easy to fail, and produce toxic gases and heavy odor during use. Nitrite is carcinogenic, harmful to the human body and the environment, and is gradually not used due to restrictions such as RoHS and REACH. Nitrite is mainly used in combination with alkaline substances (such as amines and carbonates) to enhance the passivation effect, and is used as an anti-flash rust agent, which has a passivation and anti-rust effect, and does not have a rust removal function. Sodium nitrobenzene sulfonate does not produce gas and bubbles in acidic phosphating rust and rust preventive liquid, and the film uniformity and applicability are excellent, so it has strong adhesion.

[0055] The equation for the decomposition of sodium nitrite under acidic conditions is: 2H + + 2NO 2 - →H 2 O+NO↑+NO 2 ↑. In an acidic solution, nitrite ions combine with hydrogen ions to form nitrous acid (HNO 2 ). Nitrous acid is unstable and easily decomposes into nitric oxide and nitrogen dioxide.

[0056] Comparative Example 3 does not add organic modified phosphating rust removal and rust prevention liquid. Since there is no component that reacts with rust, there is no rust removal effect, and only a film is formed on the surface of the rust layer. The adhesion, impact resistance, cross-cut test, and paint film appearance are the worst.

[0057] Comparative Example 4 did not use the sodium dihydrogen phosphate and potassium dihydrogen phosphate buffer system, and its adhesion, impact resistance, cross-cut test, and paint film appearance were all inferior to those of Example 1.

[0058] Comparative Example 5 does not add potassium molybdate, that is, it is insufficient in treating the dense rust layer and forming a dense iron molybdate passivation film.

[0059] In summary, the organic modified phosphating rust-resistant coating primer prepared by the present invention has significantly better application performance than conventional coating primers, especially when applying complex rust layers or thick rust layers, the performance of the paint film in terms of appearance, adhesion and impact resistance is exceptionally excellent.

Claims

1. An organic modified phosphating rust-proof coating primer, characterized in that: In terms of mass percentage, it is made of the following components: Organic modified phosphating rust removal and anti-rust liquid 3~10%; Water-based acrylic emulsion 50~70%; Film-forming aid 3~3.6%; Functional additives 0.5~1.2%; Pigment 7~10%; Filler 8~11%; Thickener 0.4~0.8%; Anti-settling agent 1~1.5%; Deionized water A balance; The organic modified phosphating rust removing and preventing liquid is prepared from sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid, potassium molybdate, organic sulfonate and deionized water B.

2. The organic modified phosphating rust-proof coating primer according to claim 1, characterized in that: The preparation steps of organic modified phosphating rust removal and anti-rust liquid are as follows: First, sodium dihydrogen phosphate and potassium dihydrogen phosphate are added to deionized water B, and phosphoric acid is added and mixed evenly to obtain a phosphating rust-removing and rust-preventing liquid; potassium molybdate and organic sulfonate are added and stirred to dissolve to obtain an organic modified phosphating rust-removing and rust-preventing liquid; wherein the organic sulfonate is sodium nitrobenzene sulfonate or potassium nitrobenzene sulfonate.

3. The organic modified phosphating rust-proof coating primer according to claim 2, characterized in that: The mass ratio of potassium molybdate, organic sulfonate and phosphating rust removal and anti-rust liquid is (3~5): (0.2~0.4):

100.

4. The organic modified phosphating rust-proof coating primer according to claim 2, characterized in that: The mass ratio of sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid and deionized water B is 2:2:0.85:(5~10).

5. The organic modified phosphating rust-proof coating primer according to claim 1, characterized in that: The functional additives are composed of a wetting and dispersing agent and a defoaming agent. The wetting and dispersing agent is polyether polyol, and the defoaming agent is polyether modified silicone. The mass ratio of the wetting and dispersing agent to the defoaming agent is (3~5):

1.

6. The organic modified phosphating rust-proof coating primer according to claim 1, characterized in that: The filler consists of titanium dioxide and barium sulfate; the mass ratio of titanium dioxide to barium sulfate is 1:(1~2).

7. The organic modified phosphating rust-proof coating primer according to claim 1, characterized in that: The pigment is ferric oxide, the film-forming aid is alcohol ester dodecahydrate, the thickener is hydroxyethyl cellulose, and the anti-settling agent is fumed silica.

8. A method for preparing the organic modified phosphating rust-proof coating primer according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Stir deionized water A and functional additives evenly; (2) Add pigment, filler and organic modified phosphating rust removal and rust prevention liquid and stir evenly to obtain slurry; (3) Continue to add water-based acrylic emulsion to the slurry and stir evenly; (4) Finally, add thickener, anti-settling agent and film-forming aid and stir until evenly mixed to obtain organic modified phosphating rust-resistant coating primer.

9. The method for preparing the organic modified phosphating rust-proof coating primer according to claim 8, characterized in that: In step (1), the stirring time is 10-20 min, and the stirring rate is 100-200 r / min; in step (2), the stirring time is 10-20 min, and the stirring rate is 800-1000 r / min.

10. The method for preparing the organic modified phosphating rust-proof coating primer according to claim 8, characterized in that: In step (3), the stirring time is 10 to 15 minutes, and the stirring rate is 300 to 400 r / min; in step (4), the stirring time is 10 to 15 minutes, and the stirring rate is 200 to 300 r / min.

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