Rare earth anticorrosive paint and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and particularly discloses a rare earth anticorrosive coating and a preparation method thereof.The rare earth anticorrosive coating is prepared from 5-10 parts of special rare earth compound, 30-45 parts of waterborne resin, 25-35 parts of pigment filler, 5-10 parts of auxiliaries and 10-20 parts of deionized water; wherein the auxiliaries comprise 1-5 parts of a dispersing agent, 0.1-1 part of a preservative, 0.1-1 part of a defoaming agent, 0.1-1 part of a flatting agent, 1-5 parts of a film-forming agent and 1-2 parts of an anti-freezing agent; the rare earth titanate is introduced to replace traditional titanium dioxide filler, a water-based resin system is combined, the corrosion resistance and environmental protection property of the coating are improved, the compactness and chemical stability of the coating are enhanced through the unique crystal structure of the rare earth titanate, and corrosive media such as acid, alkali and salt mist are effectively blocked.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a rare earth anti-corrosion coating and a preparation method thereof. Background Art

[0002] Corrosion and corrosion prevention are prominent issues in industries such as chemical engineering, light industry, metallurgy, electricity, textiles, printing and dyeing, shipbuilding, and construction. Corrosion causes enormous losses each year, making corrosion prevention particularly important. With the development of industry, the demand for long-term, efficient, and high-performance corrosion protection materials is increasing. This is especially true in extremely harsh environments such as marine engineering, large steel structures, and military marine equipment, which places higher demands on the corrosion resistance of coatings.

[0003] Rare earth elements, due to their unique electron shell structure and large ionic radius, exhibit strong coordination and complexing properties. The numerous empty orbitals of rare earth ions can capture unstable free radicals, rendering them inactive, thus stabilizing the coating and improving corrosion and aging resistance. Numerous public reports have reported the application of rare earth elements in anti-corrosion coatings, but these elements are typically added in the form of rare earth oxides, modified rare earth oxides, or water-soluble rare earth salts (such as rare earth nitrates). The amount and method of incorporation of the rare earth elements can significantly influence the coating's anti-corrosion effectiveness.

[0004] In view of this, this patent provides a rare earth anti-corrosion coating to better improve the corrosion resistance of the coating. Summary of the Invention

[0005] The purpose of the present invention is to provide a rare earth anti-corrosion coating and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A rare earth anti-corrosion coating comprising the following components in parts by weight:

[0008] 5-10 parts of special rare earth compound, 30-45 parts of water-based resin, 25-35 parts of pigment and filler, 5-10 parts of additive, 10-20 parts of deionized water;

[0009] The auxiliary agents include 1 to 5 parts of dispersant, 0.1 to 1 part of preservative, 0.1 to 1 part of defoaming agent, 0.1 to 1 part of leveling agent, 1 to 5 parts of film-forming agent and 1 to 2 parts of antifreeze agent.

[0010] Preferably, the special rare earth compound is a rare earth titanate having the chemical formula RE2Ti2O7, wherein RE is selected from at least one of La, Ce, and Er; the rare earth titanate is synthesized by a sol-gel method, and the specific steps include:

[0011] a. Dissolve rare earth nitrate in anhydrous ethanol to prepare a rare earth nitrate solution;

[0012] b. dissolving tetrabutyl titanate in anhydrous ethanol and adding acetic acid to form a titanium source solution;

[0013] c. Add the titanium source solution dropwise to the rare earth nitric acid solution, adjust the pH to 3-5, and stir to form a sol;

[0014] d. The sol is evaporated and dried to obtain a xerogel precursor;

[0015] e. Pre-calcining the dry gel at 400-600°C for 2-4 hours, followed by calcination at 1200-1400°C for 2-5 hours;

[0016] f. The calcined product is crushed, washed and dried to obtain a final product with a particle size D50 < 2 μm.

[0017] Preferably, the water-based resin is selected from at least one of bisphenol A water-based epoxy resin emulsion, water-based silicone-modified acrylic resin, and water-based epoxy-modified acrylic resin.

[0018] Preferably, the color filler includes 5 to 10 parts of pigment and 20 to 25 parts of filler; the pigment is selected from at least one of rare earth samarium sulfide yellow pigment, rare earth cerium sulfide red pigment, and rare earth lanthanum cerium sulfide orange pigment; the filler is composed of 10 to 15 parts of kaolin, 5 to 10 parts of mica powder, and 5 to 10 parts of talc.

[0019] Preferably, the dispersant is sodium polyacrylate or sodium hexametaphosphate; the preservative is isothiazolinone or sodium benzoate; the defoaming agent is dimethyl silicone oil or polyether siloxane copolymer; the leveling agent is polyether modified siloxane or modified acrylic leveling agent; the film-forming aid is propylene glycol butyl ether; and the antifreeze agent is ethylene glycol.

[0020] A method for preparing the rare earth anti-corrosion coating according to any one of the above items comprises the following steps:

[0021] S1. Mix the water-based resin with deionized water, stir, and then add the special rare earth compound and pigments and fillers in sequence to form a mixed slurry;

[0022] S2, grinding the mixed slurry to a particle size D50 < 5 μm to obtain a rare earth resin slurry;

[0023] S3. Add a dispersant, a preservative, a defoamer, a leveling agent, a film-forming aid and an antifreeze agent to the rare earth resin slurry, and stir for 2 to 5 hours to prepare the rare earth anti-corrosion coating.

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

[0025] (1) By introducing rare earth titanates to replace traditional titanium dioxide fillers and combining them with a water-based resin system, the corrosion resistance and environmental friendliness of the coating are improved. The unique crystal structure of rare earth titanates enhances the density and chemical stability of the coating, effectively blocking corrosive media such as acid, alkali, and salt spray, and is suitable for complex environments such as building exterior walls, steel structures, and ships. At the same time, the low VOC emissions of the water-based formula and the non-toxic design of rare earth compounds have the advantages of both protection and ecological safety.

[0026] (2) Ultrafine rare earth titanates are synthesized by the sol-gel method to ensure the purity and uniform dispersion of the material, extend the protection period and reduce maintenance requirements. In addition, the high-temperature stability of rare earth titanates further expands their application range in high-temperature industrial fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The XRD pattern of La2Ti2O7 synthesized in Example 1 of the present invention;

[0028] Figure 2 This is the XRD pattern of Er2Ti2O7 synthesized in Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1:

[0031] See also Figure 1-Figure 2 As shown, a rare earth anti-corrosion coating comprises the following components in parts by weight:

[0032] 40 parts of bisphenol A waterborne epoxy resin emulsion, 18 parts of deionized water, 8 parts of lanthanum titanate (La2Ti2O7), and 6 parts of rare earth cerium sulfide red pigment;

[0033] Fillers: 12 parts of kaolin, 7 parts of mica powder, and 6 parts of talc (25 parts in total);

[0034] Additives: 3 parts of sodium polyacrylate dispersant, 0.6 parts of isothiazolinone preservative, 0.5 parts of dimethyl silicone oil defoaming agent, 0.5 parts of polyether modified siloxane leveling agent, 3 parts of propylene glycol butyl ether film-forming aid, and 2 parts of ethylene glycol antifreeze.

[0035] A method for preparing the above-mentioned rare earth anti-corrosion coating comprises the following steps:

[0036] S1, 40 parts of bisphenol A type waterborne epoxy resin emulsion and 18 parts of deionized water were mixed, and the mixture was stirred at 500 rpm for 10 minutes to form a uniform resin liquid. 8 parts of lanthanum titanate, 6 parts of rare earth cerium sulfide red pigment, 12 parts of kaolin, 7 parts of mica powder and 6 parts of talc were added in sequence, and the mixture was stirred for 20 minutes to obtain a mixed slurry;

[0037] S2, transferring the mixed slurry to a sand mill and grinding it to a particle size D50 < 5 μm to obtain a rare earth resin slurry;

[0038] S3, to the ground slurry, 3 parts of sodium polyacrylate dispersant, 0.6 parts of isothiazolinone preservative, 0.5 parts of dimethyl silicone oil defoamer, 0.5 parts of polyether modified siloxane leveling agent, 3 parts of propylene glycol butyl ether film-forming aid and 2 parts of ethylene glycol antifreeze were added in sequence, and the mixture was stirred at 800 rpm for 3 hours to prepare a rare earth anti-corrosion coating;

[0039] Specifically, regarding the preparation of the above-mentioned lanthanum titanate, the specific steps include:

[0040] a. Dissolve a certain amount of lanthanum nitrate in anhydrous ethanol and stir until completely dissolved to form a clear lanthanum nitrate ethanol solution;

[0041] b. Dissolve tetrabutyl titanate in anhydrous ethanol, add a small amount of acetic acid as a stabilizer, and stir to mix uniformly to form a tetrabutyl titanate ethanol solution;

[0042] c. Under continuous stirring (rotation speed 300-500 rpm), the tetrabutyl titanate solution is slowly added dropwise to the lanthanum nitrate solution (dropping speed is about 1-2 mL / min). During the dropwise addition, ammonia water is added dropwise to adjust the pH of the reaction system to 3-5. The reaction temperature is controlled at 25-40°C. After the dropwise addition is completed, stirring is continued for 1-2 hours to obtain a transparent or translucent sol;

[0043] d. Transfer the sol to a 60-80°C water bath to slowly evaporate the solvent until a wet gel is formed. Place the wet gel in an oven at 80-120°C and dry it for 5-10 hours to completely remove the residual solvent to obtain a dry gel precursor.

[0044] e. Place the dry gel in a corundum crucible, place it in a muffle furnace, heat it to 400-600°C at 5°C / min, keep it warm for 2-4 hours to remove organic matter and initially form a crystalline phase, continue to heat it to 1200-1400°C, keep it warm for 2-5 hours to allow the grains to fully grow and form pure La2Ti2O7;

[0045] f. The calcined product is cooled to room temperature and ultrafinely pulverized by high-pressure airflow milling or wet sand milling to ensure that the D50 of the final particles is less than 2 μm. The pulverized powder is washed three times with deionized water to remove impurities, then dried at 80° C. and sieved through 200 mesh to obtain the final product, lanthanum titanate.

[0046] Comparative Example:

[0047] The difference from Example 1 is that, except that 8 parts of lanthanum titanate are replaced by 8 parts of lanthanum oxide (La2O3), the other components and proportions are the same as those in Example 1.

[0048] Example 2:

[0049] The difference from Example 1 is that the lanthanum titanate (La2Ti2O7) in Example 1 is replaced by an equal amount of erbium titanate (Er2Ti2O7), and the other components and proportions remain unchanged.

[0050] Experimental example:

[0051] The obtained rare earth coating was sprayed on the surface of a 120 mm × 50 mm × 0.3 mm tinplate. The test groups were grouped as follows: Group 1 was Example 1, Group 2 was a comparative example, and Group 3 was Example 2.

[0052] Water resistance, acid resistance, alkali resistance, and neutral salt spray resistance tests are carried out in accordance with relevant standards. Among them, water resistance: immersion in deionized water, 1200 hours; acid resistance: immersion in 5% H2SO4 solution, 72 hours; alkali resistance: immersion in 5% NaOH solution, 168 hours; neutral salt spray resistance: according to GB / T 1771 standard, 2400 hours; high temperature resistance (only Group 3): 500 hours at 150°C environment.

[0053] Performance evaluation criteria are as follows: coating condition: observe gloss loss, discoloration, blistering, wrinkling, and peeling; adhesion: graded according to the GB / T 9286 cross-cut method (0 is the best, 5 is the worst); rust extension: rust width at the scratch (mm);

[0054] The specific data are as follows:

[0055]

[0056]

[0057] As can be seen from the above, Group 1 (lanthanum titanate) and Group 3 (erbium titanate) performed excellently in water resistance, acid and alkali resistance, and salt spray resistance tests. The coatings showed no failure and maintained adhesion level 1. Erbium titanate also passed the high temperature resistance test (150°C / 500h), making it suitable for extreme environments.

[0058] In group 2 (lanthanum oxide comparison), the corrosion resistance decreased significantly, the rust expanded by 0.5 mm after salt spray, and the adhesion dropped to level 2, indicating that the structural advantages of rare earth titanates are obvious.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A rare earth anti-corrosion coating, characterized in that: The following components are included in parts by weight: 5-10 parts of special rare earth compound, 30-45 parts of water-based resin, 25-35 parts of pigment and filler, 5-10 parts of additive, 10-20 parts of deionized water; The auxiliary agents include 1 to 5 parts of dispersant, 0.1 to 1 part of preservative, 0.1 to 1 part of defoaming agent, 0.1 to 1 part of leveling agent, 1 to 5 parts of film-forming agent and 1 to 2 parts of antifreeze agent.

2. A rare earth anti-corrosion coating according to claim 1, characterized in that: The special rare earth compound is a rare earth titanate having a chemical formula of RE2Ti2O7, wherein RE is selected from at least one of La, Ce, and Er. The rare earth titanate is synthesized by a sol-gel method, and the specific steps include: a. Dissolve rare earth nitrate in anhydrous ethanol to prepare a rare earth nitrate solution; b. dissolving tetrabutyl titanate in anhydrous ethanol and adding acetic acid to form a titanium source solution; c. Add the titanium source solution dropwise to the rare earth nitric acid solution, adjust the pH to 3-5, and stir to form a sol; d. The sol is evaporated and dried to obtain a xerogel precursor; e. Pre-calcining the dry gel at 400-600°C for 2-4 hours, followed by calcination at 1200-1400°C for 2-5 hours; f. The calcined product is crushed, washed and dried to obtain a final product with a particle size D50 < 2 μm.

3. A rare earth anti-corrosion coating according to claim 1, characterized in that: The water-based resin is selected from at least one of bisphenol A water-based epoxy resin emulsion, water-based silicone-modified acrylic resin, and water-based epoxy-modified acrylic resin.

4. A rare earth anti-corrosion coating according to claim 1, characterized in that: The color filler includes 5 to 10 parts of pigment and 20 to 25 parts of filler; the pigment is selected from at least one of rare earth samarium sulfide yellow pigment, rare earth cerium sulfide red pigment, and rare earth lanthanum cerium sulfide orange pigment; the filler is composed of 10 to 15 parts of kaolin, 5 to 10 parts of mica powder, and 5 to 10 parts of talc powder.

5. The rare earth anti-corrosion coating according to claim 1, characterized in that: The dispersant is sodium polyacrylate or sodium hexametaphosphate; the preservative is isothiazolinone or sodium benzoate; the defoaming agent is dimethyl silicone oil or polyether siloxane copolymer; the leveling agent is polyether modified siloxane or modified acrylic leveling agent; the film-forming aid is propylene glycol butyl ether; and the antifreeze agent is ethylene glycol.

6. A method for preparing the rare earth anticorrosive coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Mix the water-based resin with deionized water, stir, and then add the special rare earth compound and pigments and fillers in sequence to form a mixed slurry; S2, grinding the mixed slurry to a particle size D50 < 5 μm to obtain a rare earth resin slurry; S3. Add a dispersant, a preservative, a defoamer, a leveling agent, a film-forming aid and an antifreeze agent to the rare earth resin slurry, and stir for 2 to 5 hours to prepare the rare earth anti-corrosion coating.

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