A water-based quick-drying anti-rust paint and its preparation process

Abstract

This invention discloses a water-based fast-drying anti-rust paint and its preparation process and method. The paint comprises a core-shell acrylic emulsion, an acrylic phosphate emulsion, a nano-composite zinc phosphomolybdate, nano-graphene, a phytic acid-modified silicon quantum dot composite, sodium metavanadate, and additives. It has excellent long-lasting anti-corrosion, fast-drying application, and environmental friendliness, and is particularly suitable for rust prevention and protection of steel substrates in high-chlorine corrosion environments such as marine environments.

Description

Technical Field

[0001] This invention belongs to the field of water-based industrial coatings technology. Background Technology

[0002] Rust-preventive coatings are the most common means of protecting metals such as steel pipes from corrosion. Water-based rust-preventive coatings, due to their low VOC content and environmental friendliness, are gradually replacing solvent-based coatings and becoming the future trend.

[0003] Existing water-based anti-rust coatings mostly use acrylic emulsions as film-forming substances, combined with anti-rust pigments and functional fillers, relying on physical shielding and passivation for protection. However, they have obvious defects in harsh high-chlorine environments: insufficient interfacial bonding force makes them easy to peel off, the protection mechanism is single and difficult to resist chloride ion corrosion, the utilization rate of nanomaterials is low and they are easy to agglomerate, it is difficult to achieve both fast drying and long-term corrosion protection, and environmental protection and protective performance cannot be balanced.

[0004] To address the aforementioned pain points, a water-based anti-rust coating is needed that combines strong interfacial adhesion, multiple layers of protection, quick drying, long-lasting corrosion resistance, and environmental friendliness and non-toxicity. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a water-based fast-drying anti-rust paint and its preparation process, which has excellent anti-rust performance.

[0006] Technical solution: To achieve the above objectives, the present invention provides a water-based quick-drying rust-preventive paint, comprising the following components by weight:

[0007] The composition includes: 40-60 parts core-shell acrylic emulsion, 10-20 parts acrylic phosphate emulsion, 15-25 parts nano-compound zinc phosphomolybdate, 3-8 parts nano-graphene, 0.3-0.8 parts polyether-modified silicone defoamer, 0.1-0.3 parts organobentonite, 0.1-0.5 parts polyurethane viscosity modifier, 0.1-0.2 parts organic amine pH adjuster, 1-3 parts polymeric dispersant, 5-10 parts film-forming aid, 10-20 parts deionized water, 0.5-3 parts phytic acid-modified silicon quantum dot composite, and 1-5 parts sodium metavanadate; wherein the weight parts of the phytic acid-modified silicon quantum dot composite are based on solid silicon quantum dots, and the phytic acid-modified silicon quantum dot composite is formed by surface hydrogen-terminated silicon quantum dots and phytic acid connected by Si-OP covalent bonds.

[0008] Furthermore, the silicon quantum dots have a particle size of 2-5 nm and a hydrogen-terminated surface.

[0009] Furthermore, in the phytic acid-modified silicon quantum dot composite, the mass ratio of silicon quantum dots to phytic acid is 1:2 to 1:5.

[0010] Furthermore, the mass ratio of the sodium metavanadate to the phytic acid-modified silicon quantum dot composite is 1:1 to 5:1.

[0011] Furthermore, the particle size of the nano-composite zinc phosphomolybdate is ≤100nm; the nano-graphene is few-layer graphene with a sheet thickness ≤5nm and a sheet diameter of 1-5μm.

[0012] Furthermore, the core-shell acrylic emulsion has a solid content of 45±2%, and the acrylic phosphate emulsion contains 5-15wt% phosphate ester monomers and has a solid content of 40±2%.

[0013] Furthermore, the organic amine pH adjuster is 2-amino-2-methyl-1-propanol; the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0014] Further, in step 1: Take 50% by weight of deionized water, organic bentonite, and polymeric dispersant and mix them together, stirring at 500-700 r / min for at least 15 minutes;

[0015] Step 2: Add nano-composite zinc phosphomolybdate and nano-graphene, disperse at high speed of 2500-3000 r / min, and then grind in a sand mill to a fineness of ≤20 microns;

[0016] Step 3: Add phytic acid-modified silicon quantum dot composite and pre-dissolved sodium metavanadate aqueous solution, and stir until homogeneous;

[0017] Step 4: Add the core-shell acrylic emulsion and the acrylate phosphate emulsion in sequence, and stir until homogeneous;

[0018] Step 5: Add the remaining deionized water, defoamer, and film-forming aid, and stir well;

[0019] Step 6: Adjust the system viscosity to the Forte 4 cup viscosity for 30-40 seconds (25℃), adjust the pH value to 8.5-9.0, and filter out the material.

[0020] Furthermore, the phytic acid-modified silicon quantum dot composite is prepared in advance by the following method:

[0021] S1, surface hydrogen-terminated silicon quantum dots with a particle size of 2-5 nm were prepared by a non-thermal plasma method;

[0022] S2, Weigh silicon quantum dots and phytic acid aqueous solution at a mass ratio of 1:2 to 1:5, first dry grind, then wet grind to complete the covalent reaction;

[0023] S3, ultrasonic dispersion for 30 minutes to obtain phytic acid modified silicon quantum dot composite dispersion.

[0024] Beneficial Effects: This invention synergistically introduces phytic acid-modified silicon quantum dot composites and sodium metavanadate into water-based acrylic anti-rust coatings, constructing a ternary synergy of silicon quantum dots, phytic acid, and sodium metavanadate. Through the synergistic effects of interfacial covalent anchoring, complementary dual passivation, nano-rivet reinforcement, and induced densification film formation, a significant improvement in coating adhesion, chloride ion corrosion resistance, and long-term anti-corrosion performance is achieved, without affecting the coating's fast-drying application performance. The specific principle is as follows:

[0025] Hydrogen-terminated silicon quantum dots have extremely high surface reactivity. The Si-H bonds on their surface can undergo dehydration reactions with the Fe-OH groups on the surface of steel substrates to form stable Fe-O-Si covalent bonds, thus solving the problem of insufficient interfacial bonding caused by traditional coatings relying solely on physical adsorption.

[0026] Phytic acid molecules contain six phosphate groups. One phosphate group forms a Si-OP covalent bond with silicon quantum dots for directional anchoring, while the remaining five phosphate groups face the metal substrate and can chelate with Fe²⁺ and Fe³⁺ to form a dense, three-dimensional network organic passivation layer on the substrate surface. Simultaneously, sodium metavanadate vanadate ions undergo a redox reaction in the cathode region of the metal surface, generating an insoluble vanadium oxide inorganic passivation film that fills the pores and defects of the organic passivation layer. This organic-inorganic dual passivation film forms a complementary structure, which can increase the chloride ion barrier capability by more than two orders of magnitude, inhibiting pitting corrosion.

[0027] 2-5nm silicon quantum dots can penetrate organic-inorganic passivation films. One end is anchored to the steel substrate surface via Fe-O-Si covalent bonds, while the other end bonds with phytic acid and organic coatings via Si-OP bonds, forming a nanoscale rivet structure that firmly anchors the passivation film and coating to the substrate surface. This solves the problems of easy passivation film detachment and poor adhesion between the coating and passivation film. The abundant active sites on the surface of silicon quantum dots can serve as preferential sites for passivation film nucleation, significantly reducing the nucleation barrier. This allows vanadium oxide passivation films and phytic acid organic passivation films to uniformly nucleate and grow on the substrate surface, avoiding pinholes and pore defects caused by excessively rapid local growth in traditional passivation films. The resulting passivation film is denser and more complete, significantly improving protection efficiency. Attached Figure Description

[0028] Figure 1 For process flow diagram;

[0029] Figure 2 This is the first page of the commissioned testing report;

[0030] Figure 3 The detailed contents of the commissioned testing report for the second embodiment are as follows. Detailed Implementation

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] This water-based quick-drying rust-preventive paint, by weight, comprises the following components:

[0033]

[0034] The aforementioned phytic acid-modified silicon quantum dot composite is formed by surface hydrogen-terminated silicon quantum dots and phytic acid covalently linked by Si-OP covalent bonds, thereby achieving directional anchoring of phytic acid on the surface of silicon quantum dots, preventing phytic acid migration and precipitation, and maximizing the chelating and passivating effect of phytic acid.

[0035] The silicon quantum dots mentioned above have a particle size of 2-5 nm and a hydrogen-terminated surface (H-SiQDs). Silicon quantum dots in this particle size range can penetrate the passivation film and directly contact the steel substrate. At the same time, they have extremely high surface reactivity, which facilitates the formation of Si-OP covalent bonds with phytic acid and Fe-O-Si covalent bonds with the substrate.

[0036] In the phytic acid-modified silicon quantum dot composite, the mass ratio of silicon quantum dots to phytic acid is 1:2 to 1:5, which ensures that the surface of silicon quantum dots is fully modified, while retaining sufficient phosphate groups for metal ion chelation.

[0037] The mass ratio of sodium metavanadate to phytic acid-modified silicon quantum dot composites is 1:1 to 5:1 to achieve optimal synergy between passivation and interface anchoring effects.

[0038] The nano-composite zinc phosphomolybdate has a particle size ≤100nm. It is a zinc phosphomolybdate-zinc phosphate composite powder with a surface modified by a silane coupling agent, which improves its dispersibility and rust prevention efficiency in water-based systems.

[0039] Nanographene is a few-layer graphene with a sheet thickness of ≤5nm and a sheet diameter of 1-5μm. Its surface is modified by hydroxylation, and it has excellent dispersion stability in aqueous systems, which can be used to construct a dense physical shielding network.

[0040] The core-shell acrylic emulsion has a solid content of 45±2% and a glass transition temperature (Tg) of 20-30℃. The core layer is a low-Tg soft monomer, and the shell layer is a high-Tg hard monomer, which takes into account the coating's fast drying, film-forming properties, and coating hardness.

[0041] Acrylic phosphate emulsion is a random copolymer of acrylic monomer and phosphate functional monomer, wherein the content of phosphate monomer is 5-15wt% and the solid content of emulsion is 40±2%. The phosphate groups can form hydrogen bonds and coordination bonds with the surface of steel substrate, synergistically improving the adhesion of the coating.

[0042] The organic amine pH adjuster is 2-amino-2-methyl-1-propanol (AMP-95); the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (dodecyl alcohol ester); the polymeric dispersant is an ammonium polyacrylate dispersant or a block copolymer dispersant; and the polyurethane viscosity modifier is a nonionic polyurethane rheology modifier.

[0043] The preparation process of water-based quick-drying anti-rust paint is as follows: Figure 1 As shown:

[0044] Phytic acid-modified silicon quantum dot composites were prepared in advance through the following three steps:

[0045] s1 employs a non-thermal plasma method, introducing a 1% volume fraction of silane-argon mixture (SiH4 / Ar) at 80 SCCM and high-purity hydrogen at 10 SCCM into the plasma reaction chamber. The radio frequency power is 150W, the pressure is below 500Pa, and hydrogen-terminated silicon quantum dot powder with a particle size of 2-5nm is collected.

[0046] s2, Weigh silicon quantum dots and phytic acid (50% aqueous solution) at a mass ratio of 1:2 to 1:5, dry grind for 10 minutes, then add the remaining phytic acid aqueous solution and grind for 10-30 minutes to form Si-OP bonds through a covalent reaction.

[0047] s3, add the mixture to deionized water and ultrasonically disperse at 300W for 30 minutes to obtain a phytic acid-modified silicon quantum dot composite dispersion with stable solid content.

[0048] The overall preparation method of water-based quick-drying anti-rust paint includes the following steps:

[0049] Step 1: According to the formula, add 50% of the total weight of deionized water, organic bentonite, and polymeric dispersant to the dispersion vessel in sequence, and stir slowly at 500-700 r / min for 15 minutes to obtain the pre-dispersed base liquid.

[0050] Step 2: Slowly add nano-composite zinc phosphomolybdate and nano-graphene to the pre-dispersed base liquid. After the feeding is completed, increase the speed to 2500-3000 r / min and disperse at high speed for 10 minutes. Transfer to a horizontal sand mill and add zirconia beads with a particle size of 0.8-1.2 mm (filling amount 60-70%). Control the grinding temperature to 40-50℃ and circulate grinding until the fineness is ≤20 microns. This temperature range can fully activate the active groups on the surface of the nano powder, while avoiding excessive temperature from causing the slurry to gel and become unstable.

[0051] Step 3: Transfer the slurry back to the dispersion vessel, reduce the rotation speed to 500-700 r / min, slowly add the phytic acid-modified silicon quantum dot composite dispersion, and at the same time, pre-dissolve the sodium metavanadate in the remaining 10% of deionized water and slowly add it, stirring for 10 minutes until uniform.

[0052] Step 4: At a speed of 500-700 rpm, slowly add the core-shell acrylic emulsion and the acrylate phosphate emulsion sequentially, stirring for 15 minutes. Ensure the emulsion and functional components are fully mixed to avoid emulsion breakage.

[0053] Step 5: At a speed of 500-700 rpm, slowly add the remaining deionized water, polyether modified silicone defoamer, and film-forming aid, and stir for 10 minutes until homogeneous.

[0054] Step 6: While stirring at a low speed of 300-500 r / min, add a polyurethane viscosity modifier to adjust to a Forte 4 cup viscosity of 30-40 seconds (25℃); add an organic amine pH adjuster to adjust the pH to 8.5-9.0, and then filter the material.

[0055] The raw materials used in the embodiments and comparative examples of this invention are all commercially available industrial-grade products, as detailed below:

[0056] Core-shell acrylic emulsion: commercially available, solid content 45%, glass transition temperature 25°C.

[0057] Acrylic phosphate emulsion: commercially available, phosphate monomer content 10wt%, solid content 40%.

[0058] Nano-composite zinc phosphomolybdate: commercially available, particle size ≤100nm, silane modified.

[0059] Nanographene: Commercially available, sheet thickness ≤5nm, sheet diameter 1-5μm, hydroxylated modified.

[0060] Polyether-modified silicone defoamer: BYK-024, commercially available.

[0061] Organic bentonite: Commercially available, industrial grade.

[0062] Polyurethane viscosity modifier: RM-2020, commercially available.

[0063] pH adjuster: AMP-95, commercially available.

[0064] Polymer dispersant: BYK-190, commercially available.

[0065] Film-forming aid: Dodecyl alcohol ester, commercially available.

[0066] Phytic acid: Commercially available, 50% aqueous solution, industrial grade.

[0067] Sodium metavanadate: Commercially available.

[0068] Hydrogen-terminated silicon quantum dots: self-made, preparation method is described in the invention description section.

[0069] Example 1:

[0070] Components: 50 parts core-shell acrylic emulsion, 15 parts acrylate phosphate emulsion, 20 parts nano-composite zinc phosphomolybdate, 5 parts nano-graphene, 0.5 parts defoamer, 0.2 parts organobentonite, 0.3 parts viscosity modifier, 0.15 parts pH adjuster, 2 parts dispersant, 8 parts alcohol ester dodecyl, 15 parts deionized water, 0.5 parts phytic acid modified silica quantum dot composite, and 2 parts sodium metavanadate. Preparation method: Follow steps 1-6 of the aforementioned preparation method, with all parameters within the specified range.

[0071] Example 2: Basically the same as Example 1, except that: the amount of phytic acid modified silicon quantum dot composite added is 1 part, and sodium metavanadate is 2 parts.

[0072] Example 3: Basically the same as Example 1, except that: the amount of phytic acid modified silicon quantum dot composite added is 2 parts, and sodium metavanadate is 2 parts.

[0073] Example 4: All components are taken from the lower limit values ​​in claim 1, and the preparation method is the same as in Example 1.

[0074] Example 5: All components are taken from the upper limit of claim 1, and the preparation method is the same as in Example 1.

[0075] Comparative Example 1: Same as Example 1, except that there is no phytic acid-modified silicon quantum dot composite and no sodium metavanadate.

[0076] Comparative Example 2 (lacking sodium metavanadate): Same as Example 2, except that only 1 part of phytic acid-modified silicon quantum dot composite was added, without sodium metavanadate.

[0077] Comparative Example 3: Same as Example 2, except that only 2 parts of sodium metavanadate were added, and no phytic acid-modified silicon quantum dot composite was used.

[0078] Comparative Example 4 (Physical Mixing):

[0079] Consistent with Example 2, except that the phytic acid-modified silicon quantum dot composite was replaced with a simple mixture of 1 part unmodified silicon quantum dots and 1.8 parts phytic acid.

[0080] Performance testing and results analysis:

[0081] 1. Test conditions: The substrate is 0.5mm cold-rolled steel sheet (Sa2.5 grade), the dry film thickness is 30±2μm, and the curing time is 7 days.

[0082] 2. Test methods: All tests were conducted in accordance with national standards (see table below for details). Test results are shown in the table below:

[0083]

[0084] Results Analysis

[0085] 1. The salt spray resistance time of Example 2 (820h) is much longer than that of Comparative Example 1 (220h), Comparative Example 2 (480h), and Comparative Example 3 (450h). This proves that the phytic acid modified silicon quantum dot composite and sodium metavanadate must be used in combination. A single component can only provide basic protection and cannot form a dense passivation film that complements organic and inorganic components, thus fully verifying the synergistic effect.

[0086] 2. Comparative Example 4, using a physical mixing method, only achieved salt spray resistance for 420 hours, and exhibited significant precipitation, a marked decrease in water resistance and damp heat resistance. The superior performance of Comparative Example 2 demonstrates that the Si-OP covalent bond between phytic acid and silicon quantum dots is crucial for maintaining stability and interfacial anchoring strength; physical mixing cannot prevent nanoparticle aggregation and small molecule loss.

[0087] 3. All examples showed adhesion level 1, while the comparative examples showed level 2. This directly demonstrates that the Fe-O-Si covalent bonds and nano-rivet structure formed by silicon quantum dots are key to improving interfacial bonding.

[0088] 4. Example 2 showed the best performance, while Example 3 showed a slight decrease in performance, indicating that there is an optimal addition threshold for nanomaterials. Excessive addition can easily lead to agglomeration, which in turn reduces the density and corrosion resistance of the coating.

[0089] 5. Example 2 achieves ultra-high corrosion resistance while maintaining a fast drying speed of ≤16 minutes and low VOC (52g / L). Although its UV aging resistance is level 2, which is slightly lower than the requirement, it fully meets the application scenarios of industrial heavy-duty anti-corrosion primer in non-direct sunlight environments.

[0090] In addition, the sample of Example 2, which exhibited the best overall performance in the test structure, was commissioned to the Wuhan Materials Protection Research Institute Co., Ltd. of China Academy of Machinery Science and Technology (Report No.: 2025-FC02054-1). The commissioned test report is as follows: Figure 2 and 3 As shown.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water-based quick-drying anti-rust paint, characterized in that, By weight, it includes the following components: The composition includes: 40-60 parts core-shell acrylic emulsion, 10-20 parts acrylic phosphate emulsion, 15-25 parts nano-compound zinc phosphomolybdate, 3-8 parts nano-graphene, 0.3-0.8 parts polyether-modified silicone defoamer, 0.1-0.3 parts organic bentonite, 0.1-0.5 parts polyurethane viscosity modifier, 0.1-0.2 parts organic amine pH adjuster, 1-3 parts polymeric dispersant, 5-10 parts film-forming aid, 10-20 parts deionized water, 0.5-3 parts phytic acid-modified silicon quantum dot composite, and 1-5 parts sodium metavanadate. The weight parts of the phytic acid-modified silicon quantum dot composite are based on solid silicon quantum dots, and the phytic acid-modified silicon quantum dot composite is formed by surface hydrogen-terminated silicon quantum dots and phytic acid connected by Si-OP covalent bonds.

2. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: The silicon quantum dots have a particle size of 2-5 nm and a hydrogen-terminated surface.

3. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: In the phytic acid-modified silicon quantum dot composite, the mass ratio of silicon quantum dots to phytic acid is 1:2 to 1:

5.

4. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: The mass ratio of sodium metavanadate to phytic acid-modified silicon quantum dot composite is 1:1 to 5:

1.

5. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: The nano-composite zinc phosphomolybdate has a particle size ≤100nm; the nano-graphene is few-layer graphene with a sheet thickness ≤5nm and a sheet diameter of 1-5μm.

6. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: The core-shell acrylic emulsion has a solid content of 45±2%, and the acrylic phosphate ester emulsion has a phosphate ester monomer content of 5-15wt% and a solid content of 40±2%.

7. The water-based quick-drying rust-preventive paint according to claim 1, characterized in that: The organic amine pH adjuster is 2-amino-2-methyl-1-propanol; the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

8. A method for preparing the water-based quick-drying anti-rust paint of claim 1, characterized in that, Includes the following steps: Step 1: Take 50% by weight of deionized water, organic bentonite, and polymeric dispersant and mix them together. Stir at 500-700 rpm for at least 15 minutes. Step 2: Add nano-composite zinc phosphomolybdate and nano-graphene, disperse at high speed of 2500-3000 r / min, and then grind in a sand mill to a fineness of ≤20 microns; Step 3: Add phytic acid-modified silicon quantum dot composite and pre-dissolved sodium metavanadate aqueous solution, and stir until homogeneous; Step 4: Add the core-shell acrylic emulsion and the acrylate phosphate emulsion in sequence, and stir until homogeneous; Step 5: Add the remaining deionized water, defoamer, and film-forming aid, and stir well; Step 6: Adjust the system viscosity to the viscosity of the Forte 4 cup in 30-40 seconds, adjust the pH value to 8.5-9.0, and filter the material.

9. The method for applying water-based quick-drying anti-rust paint according to claim 8, characterized in that: The phytic acid-modified silicon quantum dot composite was prepared in advance by the following method: S1, surface hydrogen-terminated silicon quantum dots with a particle size of 2-5 nm were prepared by a non-thermal plasma method; S2, Weigh silicon quantum dots and phytic acid aqueous solution at a mass ratio of 1:2 to 1:5, first dry grind, then wet grind to complete the covalent reaction; S3, ultrasonic dispersion for 30 minutes to obtain phytic acid modified silicon quantum dot composite dispersion.

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