Food contact safety type water-based single-component gradient barrier acrylic acid industrial anticorrosive coating with heterostructure topology as well as preparation method and application of food contact safety type water-based single-component gradient barrier acrylic acid industrial anticorrosive coating

Abstract

The invention relates to food contact safety type water-based single-component gradient barrier acrylic acid industrial anticorrosive paint with heterostructure topology as well as a preparation method and application of the food contact safety type water-based single-component gradient barrier acrylic acid industrial anticorrosive paint. The coating is mainly prepared from the following components: a zinc molybdate / bentonite compound, triethanolamine, deionized water, titanium dioxide, barium sulfate, an ammonium polyacrylate dispersing agent, acrylic resin, a polyether modified polysiloxane wetting agent, hydroxyethyl cellulose ether, a non-silicon mineral oil defoaming agent, propylene glycol phenyl ether and 1, 3-propylene glycol. A three-dimensional interpenetrating network is constructed through charge-driven self-assembly of branched acrylic resin and zinc molybdate / bentonite, a corrosive medium is forced to diffuse along a zigzag path, and compared with a traditional homogeneous coating, the retarding efficiency is improved; and meanwhile, a Fe-OOCR chelating passivation layer is generated in situ by utilizing selective enrichment of carboxyl functional groups on a metal base material interface, and a multi-stage physical barrier is formed by combining gradient distribution of the titanium dioxide-barium sulfate core-shell filler, so that geometric blocking and energy dissipation of a corrosion medium permeation path are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology, and a preparation method and application thereof. Background Art

[0002] Industrial anti-corrosion coatings have the core mission of ensuring the durability and safety of materials in key areas such as food processing, pharmaceutical manufacturing, and chemical equipment. Especially for food contact equipment (such as storage tanks, pipelines, mixing containers, etc. in food production plants), the coating must meet the stringent requirements of high-efficiency corrosion protection, food contact safety, and ease of construction. Early technologies focused on single performance optimization. For example, anti-corrosion-dominant coatings are mainly solvent-based epoxy and polyurethane systems, relying on high filler loading (such as zinc powder and phosphates) to form a physical-chemical composite anti-corrosion barrier, but there are problems such as high VOC emissions and long curing time, and the risk of migration of heavy metal components is difficult to meet the requirements of food contact material regulations such as FDA 21CFR 175.300. In addition, as a safe and environmentally friendly coating, the water-based acrylic system has the advantage of low VOC, but its homogenized molecular structure leads to limited anti-corrosion performance. Studies have shown that the diffusion coefficient (D) of the corrosive medium of traditional water-based acrylic coatings is as high as 10 -12 m 2 / s, it is difficult to form long-term protection in acidic cleaning fluids or high-salt environments.

[0003] As the industry's demand for green manufacturing and multifunctional integrated coatings escalates, existing technologies have exposed multiple bottlenecks. The most significant is the performance gap and contradiction, making it difficult to reconcile anti-corrosion performance with food contact safety. For example, corrosion inhibitors added to improve corrosion resistance, such as chromates, easily migrate to food contact interfaces, violating FDA limits on extractables. However, water-based systems that meet FDA standards lack structural design, resulting in insufficient anti-corrosion efficiency and low salt spray test performance. Furthermore, single-component water-based coatings rely on water evaporation for curing, and the film-forming process is easily affected by ambient humidity, leading to increased microporosity in the coating, insufficient single-pass film thickness, and aging resistance typically less than 500 hours. More fundamentally, the homogenized structure of traditional coatings cannot directionally control the diffusion path of corrosive media. Their high diffusion coefficient along the resin-filler interface causes the protective life to be reduced compared to the theoretical design value, severely restricting their large-scale application in harsh industrial scenarios.

[0004] Therefore, it is urgent to provide a food contact safe, corrosion resistant, highly durable and easy to construct coating and its preparation method and application. Summary of the Invention

[0005] In view of this, the present application provides a food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with a heterogeneous structure topology, as well as a preparation method and application thereof. The food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with a heterogeneous structure topology of the present invention has excellent anti-corrosion properties and food contact safety, thereby solving the problem that the anti-corrosion performance and food contact safety of existing coatings are difficult to be compatible.

[0006] In order to achieve the above objectives, this application is implemented through the following technical solutions:

[0007] A food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology is mainly prepared from the following components in the following weight ratios:

[0008]

[0009] Specifically, the zinc molybdate / bentonite composite is prepared by the following preparation method:

[0010] (1) 8-12 g of sodium bentonite was added to 490-510 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 25-30 kHz for 25-35 minutes; then, magnetic stirring was performed at a speed of 700-800 r / min for 23-25 ​​hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 57-63° C. for 11-13 hours and ground through a 200-250 mesh sieve to obtain preactivated bentonite;

[0011] (2) dissolving 2.87-3.07 g of zinc nitrate hexahydrate and 2.37-2.47 g of sodium molybdate in 199-201 mL of deionized water, adjusting the pH to 3.8-4.2 with 0.9-1.1 mol / L nitric acid, and magnetically stirring at a speed of 350-400 r / min until completely dissolved to obtain a precursor solution;

[0012] (3) 4-6 g of preactivated bentonite was dispersed in the above precursor solution, and magnetically stirred at 500-600 r / min in a water bath at 55-65° C. for 3-5 hours; then 0.9-1.1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 6.7-7.3, and stirring was continued for 1.5-2.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum dried at 75-85° C. for 11-13 hours; finally, the mixture was ground through a 325-400 mesh sieve to obtain a zinc molybdate / bentonite composite.

[0013] To achieve the above objectives, the present invention also provides a method for preparing a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating having any of the above-mentioned heterostructure topologies, comprising the following steps:

[0014] (1) adding zinc molybdate / bentonite composite and triethanolamine to deionized water, wherein the amount of deionized water is 48%-52% of the total amount of deionized water, and treating the mixture using ultrasound-shear coupling technology to form a nanosheet dispersion;

[0015] (2) titanium dioxide and barium sulfate are mixed and added to the remaining deionized water, and then a polyacrylate ammonium salt dispersant is added, followed by a high-speed stirring and dispersion treatment to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0016] (3) Then, lower the speed and add the nanosheet dispersion of step (1) dropwise to the titanium dioxide@barium sulfate core-shell filler of step (2) while stirring. After the addition is complete, increase the speed and continue stirring to disperse the mixture evenly.

[0017] (4) Slowly adding acrylic resin, polyether-modified polysiloxane wetting agent, hydroxyethyl cellulose ether, non-silicone mineral oil defoaming agent, propylene glycol phenyl ether and 1,3-propylene glycol to the mixed solution of step (3), and then reacting at a stirring speed of 700-800 r / min by a stepwise heating method to finally obtain a food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating.

[0018] Specifically, the ultrasound-shear coupling technology in step (1) is to first perform ultrasonic treatment at an ultrasonic frequency of 26-30 kHz for 25-35 minutes, and then stir at a speed of 1800-2000 r / min for 10-15 minutes.

[0019] Specifically, the high-speed stirring and dispersing treatment in step (2) is carried out at a rotation speed of 2000-2500 r / min for 60-70 minutes.

[0020] Specifically, in step (3), a peristaltic pump is used to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide@barium sulfate core-shell filler of step (2) at a speed of 18-22 mL / min, and the rotation speed during the addition process is controlled between 1000-1200 r / min; after the addition is completed, the rotation speed is adjusted to 2000-2500 r / min, and the mixture is stirred and dispersed for 60-70 minutes.

[0021] Specifically, the staged heating method in step (4) is to gradually heat the temperature from 25-35°C to 35-45°C at a rate of 1.5-2.5°C / min, and then gradually heat the temperature to 45-55°C, and each temperature stage is maintained for 15-25 minutes.

[0022] The present invention also provides an application of the food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with heterostructure topology. The food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with heterostructure topology is used for industrial anti-corrosion coatings.

[0023] The heterogeneous topological food contact safe, water-based, single-component gradient barrier acrylic industrial anticorrosive coating of the present invention constructs a three-dimensional interpenetrating network through charge-driven self-assembly of branched acrylic resin and zinc molybdate / bentonite, forcing the corrosive medium to diffuse along a tortuous path, thereby improving the blocking efficiency compared to traditional homogeneous coatings. Simultaneously, the selective enrichment of carboxyl functional groups at the metal substrate interface generates an in-situ Fe-OOCR chelating passivation layer, which, combined with the gradient distribution of titanium dioxide-barium sulfate core-shell fillers, forms a multi-level physical barrier, achieving geometric blocking and energy dissipation of the corrosive medium's penetration path. Ultrasonic-shear coupling is used to exfoliate the bentonite interlayer domains and break up zinc molybdate agglomerates. Highly dispersed driving fillers are then arranged in a directional manner. A staged temperature increase reaction is then used to promote covalent bonding between the acrylic resin carboxyl groups and the bentonite aluminum hydroxyl groups, ultimately forming a heterogeneous topological structure in a gradient environment.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The zinc molybdate / bentonite composite introduced in the present invention, with its layered nanotopology and cation exchange properties, can form a molecular-level interpenetrating network with branched acrylic resin through charge-driven self-assembly. During the coating curing process, the three-dimensional gradient distribution of the filler is precisely controlled, reshaping the microscopic heterogeneous topology of the coating. When the coating is applied to a metal substrate, the bentonite nanosheets, due to the electrostatic attraction between the surface negative charge and the acrylic acid carboxyl groups, embed themselves into the gaps between the resin molecular chains like nano-wedges, forcing the coating surface to form an ultra-flat interface. Compared with traditional water-based coatings, the friction resistance is reduced, providing atomic-scale optimization for the geometric blocking of the penetration path of corrosive media and fluid drag reduction.

[0026] (2) Under the driving force of ultrasound-shear coupling, zinc molybdate nanowhiskers and bentonite sheets are arranged in a directional manner to form a "maze barrier". Combined with the gradient concentration distribution of titanium dioxide @ barium sulfate core-shell filler (TEM shows that the thickness of the BaSO4 coating layer is 15±3nm), the Cl- ion diffusion path is extended. When the coating is exposed to a corrosive environment, Zn in zinc molybdate 2+ The sustained-release properties (ICP-MS detection, 0.8 mg / L released in 24 hours for every 5 grams of zinc molybdate / bentonite composite) react in situ with the infiltrated H2O / CO2 to generate basic zinc carbonate to block the micropores. At the same time, the carboxyl functional groups are enriched at the metal interface to form a Fe-OOCR chelating passivation layer, realizing cross-scale synergy of physical shielding and chemical passivation.

[0027] (3) The system adopts a synergistic stabilization mechanism of hydroxyethyl cellulose ether and polyacrylate ammonium salt dispersant to promote resin-filler covalent bonding in a staged temperature increase reaction. The surface dry time is ≤25 minutes, and no VOC is detected by GB / T 23986-2009 method 2. The salt spray resistance exceeds 1000 hours (HG / T 5176-2017), and the total extractable content is <2μg / cm2 in the FDA21 CFR 175.30 migration test. 2 , providing food and pharmaceutical equipment with a water-based coating solution that combines molecular-level protection accuracy, regulatory compliance, and engineering-level construction efficiency, filling the technical gap in environmentally friendly, long-lasting anti-corrosion coatings under harsh working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a graph showing the concentration change of zinc ions released in water by the zinc molybdate / bentonite composite described in this application;

[0029] Figure 2 This is a comparison chart of the Zeta potential changes of the titanium dioxide@barium sulfate core-shell filler and barium sulfate described in this application;

[0030] Figure 3 Scanning electron micrograph of a cross-section of a coating described in this application. DETAILED DESCRIPTION

[0031] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0033] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0034] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0035] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0036] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0037] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0038] The present invention provides a food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology, which is mainly prepared from the following components in the following weight ratios:

[0039]

[0040] The zinc molybdate / bentonite composite is prepared by the following preparation method:

[0041] (1) 8-12 g of sodium bentonite was added to 490-510 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 25-30 kHz for 25-35 minutes; then, magnetic stirring was performed at a speed of 700-800 r / min for 23-25 ​​hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 57-63° C. for 11-13 hours and ground through a 200-250 mesh sieve to obtain preactivated bentonite;

[0042] (2) dissolving 2.87-3.07 g of zinc nitrate hexahydrate and 2.37-2.47 g of sodium molybdate in 199-201 mL of deionized water, adjusting the pH to 3.8-4.2 with 0.9-1.1 mol / L nitric acid, and magnetically stirring at a speed of 350-400 r / min until completely dissolved to obtain a precursor solution;

[0043] (3) 4-6 g of preactivated bentonite was dispersed in the above precursor solution, and magnetically stirred at 500-600 r / min in a water bath at 55-65° C. for 3-5 hours; then 0.9-1.1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 6.7-7.3, and stirring was continued for 1.5-2.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum dried at 75-85° C. for 11-13 hours; finally, the mixture was ground through a 325-400 mesh sieve to obtain a zinc molybdate / bentonite composite.

[0044] The present invention provides a method for preparing a food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating having any of the above-mentioned heterostructure topologies, comprising the following steps:

[0045] (1) adding zinc molybdate / bentonite complex and triethanolamine to deionized water, wherein the amount of deionized water is 48%-52% of the total amount of deionized water, and treating the mixture using ultrasound-shear coupling technology, i.e., first ultrasonically treating the mixture at an ultrasonic frequency of 26-30 kHz for 25-35 minutes, and then stirring the mixture at a speed of 1800-2000 r / min for 10-15 minutes to form a nanosheet dispersion;

[0046] (2) titanium dioxide and barium sulfate are mixed and added to the remaining deionized water, and then a polyacrylate ammonium salt dispersant is added, followed by a high-speed stirring and dispersion treatment at a stirring speed of 2000-2500 r / min for 60-70 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0047] (3) lowering the speed to 1000-1200 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 18-22 mL / min while stirring. After the addition is complete, increase the speed to 2000-2500 r / min for dispersion treatment and stir for 60-70 minutes;

[0048] (4) Slowly adding acrylic resin, polyether-modified polysiloxane wetting agent, hydroxyethyl cellulose ether, non-silicone mineral oil defoaming agent, propylene glycol phenyl ether and 1,3-propylene glycol to the mixed solution of step (3), and then gradually heating the mixture from 25-35°C to 35-45°C at a rate of 1.5-2.5°C / min, and then gradually heating the mixture to 45-55°C, maintaining each temperature stage for 15-25 minutes, and reacting at a stirring speed of 700-800 r / min to finally obtain a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating.

[0049] When applied, the prepared food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with heterogeneous structural topology is used as industrial anti-corrosion coating.

[0050] Example 1

[0051] A food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology is mainly prepared from the following components in the following weight ratios:

[0052]

[0053]

[0054] First, prepare the zinc molybdate / bentonite composite as follows:

[0055] (1) 8 g of sodium bentonite was added to 490 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 30 kHz for 25 minutes; the mixture was then magnetically stirred at a speed of 800 r / min for 23 hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 57° C. for 11 hours and ground through a 200 mesh sieve to obtain preactivated bentonite;

[0056] (2) Dissolve 2.87 g of zinc nitrate hexahydrate and 2.37 g of sodium molybdate in 199 mL of deionized water, adjust the pH to 3.8 with 1.1 mol / L nitric acid, and stir magnetically at 350 rpm until completely dissolved to obtain a precursor solution;

[0057] (3) 4 g of preactivated bentonite was dispersed in the above precursor solution and magnetically stirred at 600 r / min in a 55°C water bath for 3 hours; then 0.9 mol / L sodium hydroxide was slowly added dropwise until the pH value was 6.7, and stirring was continued for 1.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum-dried at 75°C for 11 hours; finally, ground through a 325 mesh sieve to obtain a zinc molybdate / bentonite composite.

[0058] Then, a food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous structural topology was prepared according to the following steps:

[0059] (1) 1.0 part of zinc molybdate / bentonite composite and 0.5 part of triethanolamine were added to deionized water, where the amount of deionized water was 48% of the total amount of deionized water, and treated by ultrasound-shear coupling technology, that is, ultrasonic treatment was performed at an ultrasonic frequency of 26 kHz for 25 minutes, and then stirred at a speed of 1800 r / min for 10 minutes to form a nanosheet dispersion;

[0060] (2) 22 parts of titanium dioxide and 10 parts of barium sulfate were mixed and added to the remaining deionized water, and then 0.6 parts of polyacrylate ammonium salt dispersant was added. After that, high-speed stirring and dispersion treatment was performed at a stirring speed of 2000 r / min for 60 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide @ barium sulfate core-shell filler;

[0061] (3) lowering the speed to 1000 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 18 mL / min while stirring. After the addition is completed, increase the speed to 2000 r / min for dispersion treatment and stir for 60 minutes;

[0062] (4) Slowly add 40 parts of acrylic resin, 0.1 parts of polyether-modified polysiloxane wetting agent, 0.3 parts of hydroxyethyl cellulose ether, 0.1 parts of non-silicone mineral oil defoaming agent, 1.9 parts of propylene glycol phenyl ether and 0.5 parts of 1,3-propylene glycol to the mixed solution of step (3), and then gradually increase the temperature from 25°C to 35°C at a rate of 1.5°C / min, and then gradually increase the temperature to 45°C, maintaining each temperature stage for 15 minutes, and reacting at a stirring speed of 700r / min to finally obtain a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating.

[0063] Example 2

[0064] A food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology is mainly prepared from the following components in the following weight ratios:

[0065]

[0066] First, prepare the zinc molybdate / bentonite composite as follows:

[0067] (1) 10 g of sodium bentonite was added to 500 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 28 kHz for 30 minutes; then, magnetic stirring was performed at a speed of 740 r / min for 24 hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 60° C. for 12 hours and ground through a 230-mesh sieve to obtain preactivated bentonite;

[0068] (2) Dissolve 2.97 g of zinc nitrate hexahydrate and 2.42 g of sodium molybdate in 200 mL of deionized water, adjust the pH to 4.0 with 1 mol / L nitric acid, and stir magnetically at 370 rpm until completely dissolved to obtain a precursor solution;

[0069] (3) 5 g of preactivated bentonite was dispersed in the above precursor solution and magnetically stirred at 540 r / min in a 60°C water bath for 4 hours; then 1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 7.0, and stirring was continued for 2 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum-dried at 80°C for 12 hours; finally, ground through a 350 mesh sieve to obtain a zinc molybdate / bentonite composite.

[0070] Then, a food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous structural topology was prepared according to the following steps:

[0071] (1) adding 0.85 parts of zinc molybdate / bentonite composite and 0.1 parts of triethanolamine to deionized water, wherein the amount of deionized water is 50% of the total amount of deionized water, and treating the mixture using ultrasound-shear coupling technology, i.e., first ultrasonically treating the mixture at an ultrasonic frequency of 28 kHz for 30 minutes, and then stirring the mixture at a speed of 1900 r / min for 12 minutes to form a nanosheet dispersion;

[0072] (2) 20 parts of titanium dioxide and 4 parts of barium sulfate were mixed and added to the remaining deionized water, and then 1.0 part of polyacrylate ammonium salt dispersant was added. Then, the mixture was dispersed by high-speed stirring at a stirring speed of 2200 r / min for 65 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0073] (3) lowering the speed to 1100 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 20 mL / min while stirring, adjusting the speed to 2200 r / min after the addition is complete, and stirring for 65 minutes;

[0074] (4) Slowly add 53 parts of acrylic resin, 0.07 parts of polyether-modified polysiloxane wetting agent, 0.25 parts of hydroxyethyl cellulose ether, 0.13 parts of non-silicone mineral oil defoamer, 1.2 parts of propylene glycol phenyl ether and 0.4 parts of 1,3-propylene glycol to the mixed solution of step (3), and then gradually increase the temperature from 30°C to 40°C at a rate of 2°C / min, and then gradually increase the temperature to 50°C, maintaining each temperature stage for 22 minutes, and reacting at a stirring speed of 750r / min to finally obtain a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating.

[0075] Example 3

[0076] A food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous structural topology is mainly prepared from the following components in the following weight ratios:

[0077]

[0078] First, prepare the zinc molybdate / bentonite composite as follows:

[0079] (1) 12 g of sodium bentonite was added to 510 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 25 kHz for 35 minutes; the mixture was then magnetically stirred at a speed of 700 r / min for 25 hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 63° C. for 13 hours and ground through a 250-mesh sieve to obtain preactivated bentonite;

[0080] (2) Dissolve 3.07 g of zinc nitrate hexahydrate and 2.47 g of sodium molybdate in 201 mL of deionized water, adjust the pH to 4.2 with 0.9 mol / L nitric acid, and stir magnetically at 400 rpm until completely dissolved to obtain a precursor solution;

[0081] (3) 6 g of preactivated bentonite was dispersed in the above precursor solution and magnetically stirred at 500 r / min in a 65°C water bath for 5 hours; then 1.1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 7.3, and stirring was continued for 2.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum dried at 85°C for 13 hours; finally, the precipitate was ground through a 400-mesh sieve to obtain a zinc molybdate / bentonite composite.

[0082] Then, a food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous structural topology was prepared according to the following steps:

[0083] (1) adding 0.8 parts of zinc molybdate / bentonite composite and 0.05 parts of triethanolamine to deionized water, wherein the amount of deionized water is 52% of the total amount of deionized water, and treating the mixture using ultrasound-shear coupling technology, i.e., first ultrasonically treating the mixture at an ultrasonic frequency of 30 kHz for 35 minutes, and then stirring the mixture at a speed of 2000 r / min for 15 minutes to form a nanosheet dispersion;

[0084] (2) 18 parts of titanium dioxide and 2 parts of barium sulfate were mixed and added to the remaining deionized water, and then 1.8 parts of polyacrylate ammonium salt dispersant was added. Then, the mixture was dispersed by high-speed stirring at a stirring speed of 2500 r / min for 70 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0085] (3) lowering the speed to 1200 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 22 mL / min while stirring. After the addition is complete, increase the speed to 2500 r / min for dispersion treatment and stir for 70 minutes;

[0086] (4) Slowly add 60 parts of acrylic resin, 0.05 parts of polyether-modified polysiloxane wetting agent, 0.23 parts of hydroxyethyl cellulose ether, 0.12 parts of non-silicone mineral oil defoamer, 0.5 parts of propylene glycol phenyl ether and 0.45 parts of 1,3-propylene glycol to the mixed solution of step (3), and then gradually increase the temperature from 35°C to 45°C at a rate of 2.5°C / min, and then gradually increase the temperature to 55°C, maintaining each temperature stage for 25 minutes, and reacting at a stirring speed of 800r / min to finally obtain a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating.

[0087] Comparative Example 1

[0088] Prepare acrylic industrial anticorrosive coatings as follows:

[0089] (1) 0.5 parts of zinc molybdate, 0.5 parts of bentonite, and 0.5 parts of triethanolamine were added to deionized water, where the amount of deionized water was 48% of the total amount of deionized water (the total amount of deionized water was 23 parts), and the mixture was treated by ultrasonic-shear coupling technology, i.e., ultrasonic treatment was performed at an ultrasonic frequency of 26 kHz for 25 minutes, and then stirring was performed at a speed of 1800 r / min for 10 minutes to form a nanosheet dispersion;

[0090] (2) 22 parts of titanium dioxide and 10 parts of barium sulfate were mixed and added to the remaining deionized water, and then 0.6 parts of polyacrylate ammonium salt dispersant was added. Then, the mixture was dispersed by high-speed stirring at a stirring speed of 2000 r / min for 60 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0091] (3) lowering the speed to 1000 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 18 mL / min while stirring. After the addition is completed, increase the speed to 2000 r / min for dispersion treatment and stir for 60 minutes;

[0092] (4) Slowly add 40 parts of acrylic resin, 0.1 parts of polyether-modified polysiloxane wetting agent, 0.3 parts of hydroxyethyl cellulose ether, 0.1 parts of non-silicone mineral oil defoamer, 1.9 parts of propylene glycol phenyl ether and 0.5 parts of 1,3-propylene glycol to the mixed solution of step (3), and stir at a stirring speed of 700 r / min for 15 minutes to obtain an acrylic industrial anti-corrosion coating.

[0093] The main difference between Comparative Example 1 and Example 1 of the present application is that in Comparative Example 1, zinc molybdate and bentonite are physically mixed and step (4) is a room temperature process.

[0094] Comparative Example 2

[0095] Prepare acrylic industrial anticorrosive coatings as follows:

[0096] (1) 0.45 parts of zinc molybdate, 0.4 parts of bentonite, and 0.1 parts of triethanolamine were added to deionized water, where the amount of deionized water was 50% of the total amount of deionized water (the total amount of deionized water was 19 parts), and the mixture was treated by ultrasonic-shear coupling technology, i.e., ultrasonic treatment was performed at an ultrasonic frequency of 28 kHz for 30 minutes, and then stirring was performed at a speed of 1900 r / min for 12 minutes to form a nanosheet dispersion;

[0097] (2) 20 parts of titanium dioxide and 4 parts of barium sulfate were mixed and added to the remaining deionized water, and then 1.0 part of polyacrylate ammonium salt dispersant was added. Then, the mixture was dispersed by high-speed stirring at a stirring speed of 2200 r / min for 65 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0098] (3) lowering the speed to 1100 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 20 mL / min while stirring. After the addition is complete, increase the speed to 2200 r / min for dispersion treatment and stir for 65 minutes;

[0099] (4) Slowly add 53 parts of acrylic resin, 0.07 parts of polyether-modified polysiloxane wetting agent, 0.25 parts of hydroxyethyl cellulose ether, 0.13 parts of non-silicone mineral oil defoamer, 1.2 parts of propylene glycol phenyl ether and 0.4 parts of 1,3-propylene glycol to the mixed solution of step (3), and stir at a stirring speed of 750 r / min for 22 minutes to obtain an acrylic industrial anti-corrosion coating.

[0100] The main difference between Comparative Example 2 and Example 2 of the present application is that Comparative Example 2 uses physical mixing of zinc molybdate and bentonite, and step (4) is a room temperature process.

[0101] Comparative Example 3

[0102] First, prepare the zinc molybdate / bentonite composite as follows:

[0103] (1) 12 g of sodium bentonite was added to 510 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 25 kHz for 35 minutes; the mixture was then magnetically stirred at a speed of 700 r / min for 25 hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was placed in a vacuum dryer at 63° C. for 13 hours and ground through a 250-mesh sieve to obtain preactivated bentonite;

[0104] (2) Dissolve 3.07 g of zinc nitrate hexahydrate and 2.47 g of sodium molybdate in 201 mL of deionized water, adjust the pH to 4.2 with 0.9 mol / L nitric acid, and stir magnetically at 400 rpm until completely dissolved to obtain a precursor solution;

[0105] (3) 6 g of preactivated bentonite was dispersed in the above precursor solution and magnetically stirred at 500 r / min in a 65°C water bath for 5 hours; 1.1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 7.3, and stirring was continued for 2.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum-dried at 85°C for 13 hours; finally, the precipitate was ground through a 400-mesh sieve to obtain a zinc molybdate / bentonite composite.

[0106] Then prepare acrylic industrial anticorrosive coating according to the following steps:

[0107] (1) 0.8 parts of zinc molybdate / bentonite composite and 0.05 parts of triethanolamine were added to deionized water, where the amount of deionized water was 52% of the total amount of deionized water (the total amount of deionized water was 16 parts), and the mixture was treated by ultrasonic-shear coupling technology, i.e., ultrasonic treatment was performed at an ultrasonic frequency of 30 kHz for 35 minutes, and then stirring was performed at a speed of 2000 r / min for 15 minutes to form a nanosheet dispersion;

[0108] (2) 18 parts of titanium dioxide and 2 parts of barium sulfate were mixed and added to the remaining deionized water, and then 1.8 parts of polyacrylate ammonium salt dispersant was added. Then, the mixture was dispersed by high-speed stirring at a stirring speed of 2500 r / min for 70 minutes to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler;

[0109] (3) lowering the speed to 1200 r / min, and using a peristaltic pump to add the nanosheet dispersion of step (1) dropwise to the titanium dioxide @ barium sulfate core-shell filler of step (2) at a rate of 22 mL / min while stirring. After the addition is complete, increase the speed to 2500 r / min for dispersion treatment and stir for 70 minutes;

[0110] (4) Slowly add 60 parts of acrylic resin, 0.05 parts of polyether-modified polysiloxane wetting agent, 0.23 parts of hydroxyethyl cellulose ether, 0.12 parts of non-silicone mineral oil defoamer, 0.5 parts of propylene glycol phenyl ether and 0.45 parts of 1,3-propylene glycol to the mixed solution of step (3), and stir at a stirring speed of 800 r / min for 25 minutes to obtain an acrylic industrial anti-corrosion coating.

[0111] The main difference between Comparative Example 3 and Example 3 of the present application is that step (4) of Comparative Example 3 is a room temperature process.

[0112] Comparative Example 4

[0113] Prepare conventional acrylic anticorrosive coatings as follows:

[0114] 48 parts of acrylic resin, 20 parts of deionized water, 0.2 parts of triethanolamine, 0.15 parts of sodium nitrite, 0.5 parts of bentonite, 22 parts of titanium dioxide, 5 parts of barium sulfate, 0.1 parts of polysiloxane wetting agent, 0.9 parts of polymer copolymer dispersant, 0.1 parts of silicone defoaming agent, 0.3 parts of hydroxyethyl cellulose ether and 2.4 parts of propylene glycol were added in sequence, and stirred at a speed of 550 r / min for 13 minutes to obtain a conventional acrylic anti-corrosion coating.

[0115] The main difference between Comparative Example 4 and the examples of the present application is that Comparative Example 4 is a preparation of a conventional acrylic anti-corrosion coating.

[0116] Application Example 1

[0117] 80.0 g of Example 1 was weighed, and then 4.0 g of deionized water was added thereto for dilution, and the mixture was stirred and mixed. The indicators were measured according to the following detection method.

[0118] Application Example 2

[0119] 80.0 g of Example 2 was weighed, and then 4.0 g of deionized water was added thereto for dilution, and the mixture was stirred and mixed. The indicators were measured according to the following detection method.

[0120] Application Example 3

[0121] 80.0 g of Example 3 was weighed, 4.0 g of deionized water was added thereto for dilution, the mixture was stirred and mixed, and the indicators were measured according to the following detection method.

[0122] Comparative Application Example 1

[0123] Weigh 80.0 g of Comparative Example 1, then add 4.0 g of deionized water to dilute it, stir and mix, and measure the indicators according to the following detection method.

[0124] Application Comparative Example 2

[0125] Weigh 80.0 g of Comparative Example 2, then add 4.0 g of deionized water to dilute it, stir and mix, and measure the indicators according to the following detection method.

[0126] Application Comparative Example 3

[0127] Weigh 80.0 g of Comparative Example 3, then add 4.0 g of deionized water to dilute it, stir and mix, and measure the indicators according to the following detection method.

[0128] Comparative Application Example 4

[0129] Weigh 80.0 g of Comparative Example 4, then add 4.0 g of deionized water to dilute it, stir and mix, and measure the indicators according to the following detection method.

[0130] Spraying method:

[0131] The present invention uses the anti-corrosion coatings of Application Examples 1 to 3 and Comparative Examples 1 to 4, and carries out coating operations in accordance with the SY / T 0407-2012 specification standard. In the coating process, the anti-corrosion area of ​​the stainless steel plate is first subjected to a detailed surface pretreatment, aiming to remove the oxide scale, rust and oil stains on its surface, and ensure good adhesion between the coating and the substrate. After completing the above treatment and waiting for it to be fully dried, the surface of the stainless steel plate is treated by sandblasting to Sa 2.5 level specified in GB 8923-88. This level represents that the surface treatment reaches a near-white level, with a high degree of cleanliness and surface roughness, laying a solid foundation for the effective adhesion of subsequent coatings. Subsequently, the surface dust is removed by methods such as compressed air blowing or vacuum cleaning. During this process, it is necessary to ensure that the cleanliness of the surface dust is not lower than Level 3 specified in ISO 8502-3 to avoid dust particles from adversely affecting the quality of the coating. At the same time, the surface anchor depth is strictly controlled and adjusted to an appropriate range of 40 μm to 70 μm according to the SY / T 0319-2021 specification; or to the "medium (G)" level according to the ISO 8503-2 standard to ensure that the coating has good mechanical anchoring performance. The coating is applied by spraying. Before coating, the anti-corrosion coatings of Application Examples 1 to 3 and Application Comparative Examples 1 to 4 are respectively added to the spray gun, and the thickness of the spray is 40 μm to 60 μm.

[0132] After the first spraying process is complete, the coated workpiece is air-cured in a darkened environment for 5 hours. This process utilizes natural environmental conditions to avoid uneven curing or other adverse effects that could be caused by sunlight, ensuring a stable and uniform curing process. After the anti-corrosion coating is fully cured, the thickness of the coating is accurately measured at 10 different locations using an anti-corrosion coating thickness gauge in accordance with relevant measurement specifications, and the measurement data is carefully recorded. It is important to note that to ensure the optimal balance of coating quality and performance, the thickness of the anti-corrosion coating formed in a single spraying process should be strictly controlled and should not exceed 80μm. After the entire coating operation is completed, the coating thickness is monitored not only at individual measurement points, but also across the entire coating to ensure it meets pre-defined design requirements. Following thickness measurement, the overall condition of the anti-corrosion coating is carefully inspected, utilizing specialized testing methods such as visual inspection combined with non-destructive testing techniques, focusing on detecting defects such as leaks, pinholes, and bubbles. Once the above defects are found, they should be repaired immediately using a method that matches the original spraying process to ensure the integrity and continuity of the coating.

[0133] After completing the above operations, the workpiece is moved to a shaded and well-ventilated area and allowed to rest for five days. This rest period allows the coating to further post-cure under stable environmental conditions, releasing internal stresses while ensuring that the coating surface is free of defects caused by environmental factors or self-reactions. After five days of observation and confirmation that the anti-corrosion coating surface is free of defects, the workpiece can be officially put into use to ensure its long-term and stable anti-corrosion performance under actual working conditions.

[0134] After completing all the above operations on the coated workpieces of all the above embodiments and comparative examples, performance tests were performed according to the following test items:

[0135] Table 1 Performance test standards of coated workpieces of samples

[0136] Project Name Test standards Water resistance HG / T4758-2014 Neutral salt spray resistance HG / T5176-2017 Salt water resistant (3% sodium chloride solution) HG / T4758-2014 Resistance to artificial weathering HG / T4758-2014 Volatile organic compound (VOC) content GB / T23986-2009 Method 2 bending test HG / T4758-2014 Impact resistance HG / T4758-2014 Fineness HG / T4758-2014 Storage stability HG / T4758-2014 Pencil hardness (scratch) HG / T4758-2014 Migration testing of food contact coatings FDA21CFR175.300

[0137] Various performance tests were performed on Examples 1-3 and Comparative Examples 1-4, and the results are shown in Table 2.

[0138] Table 2 Test results of coating workpiece performance of samples

[0139]

[0140]

[0141] The test results in the table above show that the water-based, one-component food contact safety coating developed by the present invention not only strictly meets food contact safety standards but also exhibits comprehensive performance advantages far exceeding those of the formulations in Comparative Examples 1-4. The coating exhibited no blistering, discoloration, or discoloration during a 72-hour water resistance test, and remained intact after 1000 hours of neutral salt spray, 144 hours of salt water immersion, and 1200 hours of artificial weathering. This demonstrates the efficient blocking capability of the three-dimensional interpenetrating network and gradient filler distribution based on the heterogeneous structural topology against the diffusion path of corrosive media. The coating surface fineness reached 20 μm, which, combined with its 2 mm bending deformation and 50 cm impact resistance, demonstrates its ability to maintain a dense barrier structure under high mechanical stress. The undetectable VOC content and the passing of the FDA migration test confirm the system's precise suppression of hazardous substance migration. Through the slow-release passivation of the zinc molybdate / bentonite complex and the synergistic chelation of the carboxyl-metal interface, the coating not only achieves multi-level dissipation of corrosion energy, but also builds a dual guarantee of long-term protection and safety compliance in food contact scenarios. It is suitable for harsh environments such as food processing equipment and pharmaceutical containers, and provides innovative solutions for industrial corrosion protection and food safety.

[0142] The effectiveness of the present invention is not only verified by the above test results, but also supported by the zinc molybdate / bentonite composite and preparation process used in the present invention:

[0143] This patent realizes the topological design of zinc molybdate / bentonite composite to achieve Zn 2+ Precise and controlled release. Figure 1 As shown in the figure, when the zinc molybdate / bentonite composite is exposed to a corrosive environment, the Zn 2+ It is continuously released at a sustained release rate of 0.8 mg / L and reacts in situ with the infiltrating H2O / CO2 to form insoluble basic zinc carbonate. This dynamic self-repair mechanism not only effectively blocks the micropores formed during the coating curing process, but also continuously repairs microcracks caused by mechanical stress or aging during long-term service, breaking through the limitations of the static barrier of traditional anti-corrosion coatings. Experiments have shown that this slow-release passivation process increases the tortuosity of the diffusion path of the corrosive medium, significantly delaying the diffusion of Cl- and H + The penetration rate of corrosion factors provides dynamic protection for 1000h neutral salt spray, which is more than 3 times the anti-corrosion efficiency of the traditional system (240h).

[0144] The titanium dioxide @ barium sulfate core-shell filler of the present invention is based on the heterogeneous nucleation theory and studies the interface control mechanism of the titanium dioxide @ barium sulfate core-shell filler. Figure 2 As shown in the figure, the ionization of the hydroxyl groups on the surface of pure titanium dioxide makes its Zeta potential -3.6mV (pH=7.0). The negative charge is relatively high, which easily generates electrostatic repulsion with the resin matrix, resulting in uneven dispersion. However, in the titanium dioxide @ barium sulfate core-shell system, the barium sulfate shell partially shields the hydroxyl groups on the surface of titanium dioxide. At the same time, the weak ionization characteristics of barium sulfate are introduced, and the overall Zeta potential rises to -0.96mV (pH=7.0), which significantly reduces the charge repulsion with the resin matrix, reduces the filler-resin interface repulsion, and forms a dense coating. Through the directional deposition of barium sulfate on the surface of titanium dioxide, a core-shell structure with a charge matching effect is constructed. The hydroxyl groups on the surface of titanium dioxide (≡Ti-OH) and the barium sulfate precursor (SO4 2- ) forms ≡Ti-O-SO3 through Lewis acid-base reaction - Transition state, induced Ba 2+ Heterogeneous nucleation occurs on the TiO2 surface. The change in Zeta potential (-3.6mV→-0.96mV) indicates that the BaSO4 coating effectively shields the surface charge of TiO2 and reduces the filler / resin interface energy. The core-shell structure adopts a "hard core-soft shell" design. When the coating is impacted by external forces, the BaSO4 shell absorbs energy through plastic deformation, while TiO2 maintains structural integrity. In addition, the synergistic effect of micron-grade titanium dioxide and barium sulfate enhances the physical shielding ability of the coating against corrosive media, resulting in no rust in the 144-hour salt water immersion test, and the corrosion resistance is improved by 50% compared to the control example (96 hours).

[0145] The present invention designs a cross-scale heterogeneous topological structure of the coating, such as Figure 3The structure is clearly shown in the figure. The acrylic resin covalently bonds with the aluminum hydroxyl groups (≡Al-OH) of the bentonite through carboxyl groups (-COOH), forming a three-dimensional interpenetrating network. The titanium dioxide@barium sulfate core-shell filler is oriented and arranged through "sedimentation-shearing" to fill the interlayer pores, forming a micron-scale physical barrier at the resin-bentonite interface. This achieves a gradient arrangement of fillers from the nanoscale (zinc molybdate / bentonite) to the microscale (titanium dioxide@barium sulfate), forming a cross-scale heterogeneous topology, reducing porosity and improving mechanical strength. Experiments have shown that this structure enables the coating to achieve an impact resistance of 50 cm (compared to only 40 cm in the comparative example) and a pencil hardness of HB (compared to 2B in the comparative example). At the same time, the total extractable content meets FDA testing, perfectly balancing corrosion protection and food contact safety.

[0146] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A food contact safe, water-based, one-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous topology, characterized by: It is mainly prepared from the following components in the following weight ratios:

2. The food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating with heterogeneous topology according to claim 1, characterized in that: The zinc molybdate / bentonite composite is prepared by the following preparation method: (1) 8-12 g of sodium bentonite was added to 490-510 mL of deionized water and ultrasonically dispersed at an ultrasonic frequency of 25-30 kHz for 25-35 minutes; then, magnetic stirring was performed at a speed of 700-800 r / min for 23-25 ​​hours. After standing, the upper suspension was removed and the precipitate was retained. The precipitate was vacuum dried at 57-63° C. for 11-13 hours and ground through a 200-250 mesh sieve to obtain preactivated bentonite; (2) dissolving 2.87-3.07 g of zinc nitrate hexahydrate and 2.37-2.47 g of sodium molybdate in 199-201 mL of deionized water, adjusting the pH to 3.8-4.2 with 0.9-1.1 mol / L nitric acid, and magnetically stirring at a speed of 350-400 r / min until completely dissolved to obtain a precursor solution; (3) 4-6 g of preactivated bentonite was dispersed in the above precursor solution, and magnetically stirred at 500-600 r / min in a water bath at 55-65° C. for 3-5 hours; then 0.9-1.1 mol / L sodium hydroxide was slowly added dropwise until the pH value was 6.7-7.3, and stirring was continued for 1.5-2.5 hours. The precipitate was separated by centrifugation, washed with an appropriate amount of deionized water, and then vacuum dried at 75-85° C. for 11-13 hours; finally, the mixture was ground through a 325-400 mesh sieve to obtain a zinc molybdate / bentonite composite.

3. A method for preparing a food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with a heterogeneous topology according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) adding zinc molybdate / bentonite composite and triethanolamine to deionized water, wherein the amount of deionized water is 48%-52% of the total amount of deionized water, and treating the mixture using ultrasound-shear coupling technology to form a nanosheet dispersion; (2) titanium dioxide and barium sulfate are mixed and added to the remaining deionized water, and then a polyacrylate ammonium salt dispersant is added, followed by a high-speed stirring and dispersion treatment to induce barium sulfate to coat the titanium dioxide particles in a heterogeneous nucleation manner to obtain a titanium dioxide@barium sulfate core-shell filler; (3) Then, lower the speed and add the nanosheet dispersion of step (1) dropwise to the titanium dioxide@barium sulfate core-shell filler of step (2) while stirring. After the addition is completed, increase the speed and continue stirring to disperse the mixture evenly. (4) Slowly adding acrylic resin, polyether-modified polysiloxane wetting agent, hydroxyethyl cellulose ether, non-silicone mineral oil defoaming agent, propylene glycol phenyl ether and 1,3-propylene glycol to the mixed solution of step (3), and then reacting at a stirring speed of 700-800 r / min by a stepwise heating method to finally obtain a food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating.

4. The method for preparing the food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous topology according to claim 3, characterized in that: The ultrasound-shear coupling technology in step (1) is to first perform ultrasonic treatment at an ultrasonic frequency of 26-30 kHz for 25-35 minutes, and then stir at a speed of 1800-2000 r / min for 10-15 minutes.

5. The method for preparing the food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous topology according to claim 3, characterized in that: The high-speed stirring and dispersing treatment in step (2) is carried out at a rotation speed of 2000-2500 r / min and stirring for 60-70 minutes.

6. The method for preparing the food contact safe water-based single-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous topology according to claim 3, characterized in that: In step (3), a peristaltic pump is used to dropwise add the nanosheet dispersion of step (1) to the titanium dioxide@barium sulfate core-shell filler of step (2) at a speed of 18-22 mL / min, and the rotation speed during the addition process is controlled between 1000-1200 r / min; after the addition is completed, the rotation speed is adjusted to 2000-2500 r / min, and the mixture is stirred and dispersed for 60-70 minutes.

7. The method for preparing the food contact safe water-based one-component gradient barrier acrylic industrial anticorrosive coating with heterogeneous topology according to claim 3, characterized in that: The staged heating method in step (4) is to gradually heat the temperature from 25-35°C to 35-45°C at a rate of 1.5-2.5°C / min, and then gradually heat the temperature to 45-55°C, and each temperature stage is maintained for 15-25 minutes.

8. Use of a food contact safe water-based one-component gradient barrier acrylic industrial anti-corrosion coating with a heterogeneous topology according to any one of claims 1-2, characterized in that: The food contact safe water-based single-component gradient barrier acrylic industrial anti-corrosion coating with heterogeneous structural topology is used for industrial anti-corrosion coatings.

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