Two-component water-based coating filler and preparation method thereof

Abstract

The application provides a two-component water-based coating filler and a preparation method thereof. The corrosion-resistant cadmium-doped Fe3O4 nanosphere particles are prepared under harsh (extremely high temperature) hydrothermal conditions, then the high-purity magnetic particles are obtained by activating and removing impurities through acid pickling, and the magnetic nanosphere is used as a core, and a silicon oxide shell is directionally adsorbed on the surface of the core, so that the magnetic suspension liquid with high suspension, high compatibility and good stability is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coatings, and particularly relates to a two-component water-based coating filler and a polyurethane composite coating and a preparation method thereof. BACKGROUND

[0002] Waterborne polyurethane refers to a polyurethane emulsion in which polyurethane is dispersed in water as a solvent. Solvent-based polyurethane is widely used, but the use of organic solvents can cause air pollution and is toxic. In recent years, people have paid more and more attention to environmental protection, which has promoted the development and research of waterborne polyurethane. Waterborne polyurethane is widely used in adhesives, coatings and other fields, and is concerned because of its environmental friendliness and safety. Polyurethane has the characteristics of good wear resistance, high load, high tear strength, low temperature resistance, oil resistance and ozone resistance, and the advantages of diversified raw materials and adjustable molecular structure, which makes polyurethane more deeply involved in the industries of elastomers, foam plastics, coatings, adhesives and the like. It cannot be denied that polyurethane also has its own shortcomings, such as poor solvent resistance, weather resistance and heat resistance, which greatly reduces its application width in coatings. At present, the modification methods of waterborne polyurethane can be divided into acrylic modification, epoxy resin modification, polysiloxane modification and natural product modification according to different modifiers. Recently, polymer composites have attracted a lot of attention, and inorganic nanoparticles can improve the mechanical properties, optical properties, thermal properties, corrosion resistance and magnetic properties of polymer materials.

[0003] Magnetic nanoparticles have potential applications in biomedical, industrial, military and other fields due to their inherent magnetic properties, microstructure, large specific surface area, surface charge and low toxicity. Due to its biocompatibility and chemical stability, magnetite is concerned and used in targeted drug delivery systems. Various methods have been applied to develop this material. Due to its hydrophobicity, magnetic materials can be easily aggregated. Surface modification helps to improve the stability of nanoparticles and can provide additional functional groups that can be used for other applications. One way to avoid nanoparticle aggregation is to coat a layer of water-soluble material on the surface of the nanoparticles. This material is usually a core of magnetite, coated with other materials on the surface. The common coating materials are multi-metal oxide or other inorganic materials as the shell, including titanium dioxide, silicon dioxide, aluminum oxide, zirconium dioxide, etc. Silicon dioxide and its derivatives can be used to modify the surface properties of magnetic nanoparticles. Because silicon dioxide is an inert compound, it can provide good acid and alkali resistance and high temperature stability. At the same time, silicon dioxide has high transmittance in the ultraviolet region, so it can be used as an anti-reflective material. The combination of magnetite and silicon dioxide can achieve stronger electromagnetic loss performance.

[0004] As CN102807775B a kind of waterproof and oil-proof magnetic SiO2 / Fe3O4 Composite particle preparation method, comprising:FeCl2·4H2O, Na2SO3, polyvinylpyrrolidone and NaOH are dissolved in deionized water, at 100 ℃~180 ℃ 8h~16h, after separation, washing, drying, obtain Fe3O4 Particle;Fe3O4 Particle is uniformly dispersed in ethanol, add ammonia, while stirring, add tetraethyl orthosilicate, continue stirring at 5 ℃~50 ℃ 8h~16h, after separation, washing, drying, obtain waterproof and oil-proof magnetic SiO2 / Fe3O4 Composite particle, by wrapping fluorosilane preparation product improves performance, production process is simple, the strong implementability of production, high yield.The waterproof and oil-proof magnetic SiO2 / Fe3O4 Composite particle or product of the present application has good waterproof and oil-proof property, and can be widely used in coatings, medical machinery, steel corrosion prevention and other aspects.

[0005] As CN109627906B a kind of double-layer inclusion structure's super-hydrophobic graphene anticorrosive coating and its preparation method belong to super-hydrophobic anticorrosive coating technical field, can solve the current super-hydrophobic coating structure and performance instability, super-hydrophobic coating anticorrosive performance is poor, and cannot be prepared in large scale and other problems.The present application includes the following steps: first, synthesis a kind of nano-particle oil dispersion with low surface energy, and good dispersibility graphene / resin composite oil dispersion;Second, spray graphene / resin composite oil dispersion and nano-particle oil dispersion on metal substrate in turn, to prepare a double-layer inclusion structure coating.Compared with traditional super-hydrophobic anticorrosive coating, the hydrophobic performance and anticorrosive performance are more excellent, the surface structure and performance are more stable, and large-scale controllable preparation can be realized, which accelerates the engineering application of super-hydrophobic coating in the field of corrosion protection. SUMMARY

[0006] The present application provides a kind of two-component water-based paint filler preparation method, by preparing corrosion-resistant cadmium-doped Fe3O4 Nanosphere particles under harsh (extremely high temperature) hydrothermal conditions, then by acid washing activation and impurity removal obtain high-purity magnetic particles, and with magnetic nanosphere as core, directional adsorption silica shell on its surface, obtain high-suspension, high compatibility, good stability magnetic suspension, when used as water-based paint filler, the filler is highly dispersed in coating, and the coating has good physical and chemical properties, such as tensile strength and corrosion resistance.

[0007] A two-component water-based paint filler preparation method includes the following steps:

[0008] (1) 5-8mM FeCl3 . 6H2O, 0.5-1 mM CdCl2 .6H2O metal salt is added to an ethanol-deionized water solution, after stirring to uniformity, 3-4 g / L tetrahydroxypropyl ethylenediamine, 1-2 g / L ethylenediaminetetraacetic acid complexing agent are sequentially added, then 0.02-0.04 g / L 2,2'-dipyridyl is added as a stabilizer, 10-15 mL NaBH4 is added as a reducing agent, after stirring to uniformity, sodium acetate is added as an alkali source, pH is adjusted to 7.5-8.5, to obtain a precursor solution;

[0009] (2) The precursor solution is placed in a stainless steel autoclave without a liner, air in the autoclave is discharged using nitrogen, then the autoclave is sealed, temperature is raised to 300-310°C at a rate of 5-10°C / min, and isothermal treatment is performed for 24-48 h, and then natural cooling to room temperature is performed.

[0010] (3) The hydrothermal product is magnetically separated, and is subjected to activation and acid washing for purification: the magnetically separated hydrothermal product is placed in a mixed solution of 98 wt.% H2SO4 and 30 wt.% H2O2 in a volume ratio of 1-2:1, and is treated for 2-3 min at a temperature of 30°C with motor stirring, after activation and acid washing for purification, deionized water and ethanol are sequentially and repeatedly used for cleaning until neutral, and a 10-20 wt.% magnetic particle suspension is prepared, the solvent of the suspension being composed of a polyether-modified silicone wetting agent, ethanol and deionized water.

[0011] (4) Ammonia water is added to the magnetic particle suspension prepared in step (3), stirring is performed for 10-20 min, ethyl silicate is added, motor stirring is performed for 12-14 h at a temperature of 10-14°C, then the product is filtered and washed, and vacuum drying is performed, to obtain (Cd-Fe)O x @SiO2 filler.

[0012] In certain embodiments, the content of the polyether-modified silicone wetting agent is 4-5 wt.%.

[0013] In certain embodiments, the volume ratio of ethanol and deionized water in steps (1) and (3) is 1:7-9.

[0014] In certain embodiments, the saturation magnetization of the magnetic particles after activation and acid washing for purification in step (3) is 62.7 emu / g, the remanence is 4.23 emu / g, and the coercivity is Hc=41.8 G.

[0015] In certain embodiments, the saturation magnetization of the (Cd-Fe)O x @SiO2 filler is 25.3 emu / g.

[0016] In certain embodiments, the amount of the ethyl silicate is 3-4 g, and the amount of the ammonia water is 5-8 mL.

[0017] In some embodiments, the (Cd-Fe)O x The core has a size of 20-70 nm, and the SiO2 shell has a thickness of 10-30 nm.

[0018] In some embodiments, the (Cd-Fe)O x The (Cd-Fe)O x The mass concentration of the SiO2 filler is 40-50 wt%, and the mass concentration of the wetting agent is 1-2 wt.%.

[0019] A preparation method of a two-component water-based paint, comprising the following steps:

[0020] (A) Preparation method of component A: uniformly stir the water-based hydroxyl acrylic resin, wetting dispersant, defoaming agent, leveling agent, deionized water according to the formula amount, then add the filler suspension, uniformly stir at high speed of 800-1200 rpm, and then add the cosolvent and thixotropic thickener and uniformly stir at medium speed of 600-800 rpm.

[0021] (B) Preparation method of component B: uniformly mix the hydrophilic modified isocyanate curing agent and propylene glycol diacetate to obtain.

[0022] (C) In use, uniformly mix component A and component B according to the mass ratio of (5.5-10):1, and then spray on the surface of the substrate.

[0023] The filler suspension is prepared by the following steps.

[0024] (1) 5-8 mM FeCl3 . 6H2O, 0.5-1 mM CdCl2 . 6H2O metal salts are added to an ethanol-deionized water solution, uniformly stirred, then 3-4 g / L tetrahydroxypropyl ethylenediamine, 1-2 g / L ethylenediaminetetraacetic acid complexing agent are added in sequence, then 0.02-0.04 g / L 2,2'-dipyridyl is added as a stabilizer, 10-15 mL NaBH4 is added as a reducing agent, uniformly stirred, then sodium acetate is used as an alkali source to adjust the pH to 7.5-8.5 to obtain a precursor solution;

[0025] (2) The precursor solution is placed in a stainless steel hydrothermal reaction kettle without lining, nitrogen is used to discharge the air in the reaction kettle, then the reaction kettle is sealed, heated to 300-310℃ at a rate of 5-10℃ / min, and kept for 24-48 h, and then naturally cooled to room temperature.

[0026] (3) Magnetic separation of the hydrothermal product and activation acid washing purification: the magnetic separation of the hydrothermal product is placed in a mixed solution of 98wt.% H2SO4 and 30wt.% H2O2 with a volume ratio of 1-2:1 for 2-3min at a temperature of 30℃ with motor stirring, and after the activation acid washing purification, the product is repeatedly cleaned with deionized water and ethanol in sequence until neutral, and a 10-20wt.% magnetic particle suspension is prepared, the solvent of which is composed of polyether modified silicone wetting agent, ethanol and deionized water.

[0027] (4) Ammonia is added to the magnetic particle suspension prepared in step (3), stirred for 10-20min, and ethyl silicate is added, stirred with a motor for 12-14h at a temperature of 10-14℃, then the product is filtered and washed, and vacuum dried to obtain (Cd-Fe)O x @SiO2filler, the (Cd-Fe)O x @SiO2filler is ultrasonically dispersed in deionized water containing a wetting agent to obtain a filler suspension, the mass concentration of (Cd-Fe)O x @SiO2is 40-50wt%, and the mass concentration of the wetting agent is 1-2wt.%.

[0028] An aqueous two-component polyurethane coating, comprising an A component and a B component; the mass ratio of the A component and the B component is (5.5-10):1.

[0029] The A component comprises the following components by mass: 40-65 parts of an aqueous hydroxyl acrylate resin, 0.5-3 parts of a wet dispersing agent, 0.5-3 parts of an antifoaming agent, 5-10 parts of a cosolvent, 10-25 parts of a filler suspension, 0.5-3 parts of a leveling agent, 0.5-5 parts of a thixotropic thickening agent, and 15-25 parts of deionized water;

[0030] The B component comprises the following components by mass: 60-80 parts of a hydrophilic modified isocyanate curing agent and 10-15 parts of propylene glycol diacetate.

[0031] The wet dispersing agent is selected from at least one of TEGO 4100, TEGO 755W and BYK-190; the antifoaming agent is selected from at least one of BYK022, BYK093, TEGO Airex 901W and TEGO Foamex 810.

[0032] The cosolvent is selected from at least one of propylene glycol methyl ether, ethylene glycol butyl ether and dipropylene glycol methyl ether.

[0033] The flow leveling agent is selected from at least one of TEGO-450, BYK-381, TEGO Glide 410, TEGO Glide 4100; the thixotropic thickening agent is selected from at least one of Borchi 0620, RHEOLATE 299.

[0034] The application adopts a hydrothermal method to prepare magnetic nano Fe3O4, which refers to using water and ethanol as a hydrothermal reaction medium, and performing a reaction in a sealed inert atmosphere reaction kettle at a high temperature of 300-310 DEG C and a high pressure of about 20-40 MPa. The filling degree of the hydrothermal reaction is 40-80%, preferably 75%. When the temperature is 310 DEG C, the pressure in the reaction kettle is about 32 MPa. FeCl3 . 6H2O and CdCl2 . 6H2O are used as metal sources, and four-hydroxy propyl ethylenediamine and ethylenediaminetetraacetic acid EDTA are used as a double-component composite complexing agent to effectively complex iron and cadmium ions, shorten the distance between the two, and facilitate the formation of an alloy structure. Then, 2,2'-dipyridyl is added as a stabilizer to stabilize the metal ion state. Then, NaBH4 is used as a reducing agent to reduce part of Fe 3+ to Fe 2+ , and Cd 2+ to Cd. Sodium acetate is used as an alkali source to generate cadmium-doped Fe3O4 magnetic particles through dehydration. Under extremely high hydrothermal temperature and pressure conditions, the saturation magnetic intensity of the obtained cadmium-doped Fe3O4 magnetic particles decreases, but compared with Fe3O4 or other FeO X or CdO, it has extremely high corrosion resistance. Based on the above performance, the Fe3O4, FeO X or CdO is removed, and the obtained magnetic particles after purification are high-purity cadmium-doped Fe3O4 magnetic particles. In order to prepare a magnetic core-shell structure, it is necessary to introduce active groups, mainly hydroxyl groups, on the surface of the above-mentioned cadmium-doped Fe3O4 magnetic nanoparticles. Sulfuric acid reacts with excess FeOx and CdO which are easily corroded, and the obtained high-purity cadmium-doped Fe3O4 magnetic particles after purification react with hydrogen peroxide in sulfuric acid and hydrogen peroxide as follows: H2SO4+H2O2→H3O + +HSO4 - +O, realizing the hydroxylation of the surface of the cadmium-doped Fe3O4 magnetic particles. During the purification and activation process, attention should be paid to the time, which should not be longer than 4 min to avoid excessive corrosion.

[0035] Then, silica is directionally adsorbed on the surface of the hydroxylated cadmium-doped Fe3O4 magnetic particles. The directional adsorption mechanism is as follows: an alkaline condition is selected, and hydroxide is provided by ammonia. TEOS is first hydrolyzed under alkaline conditions. The mechanism is that OH -First, a nucleophilic reaction occurs with the silicon nucleus to generate silanol, and hydrogen bonds are formed between the hydroxyl groups of the silanol and the hydroxyl groups on the surface of the cadmium-doped Fe3O4 magnetic particles. Then, further condensation occurs on the basis of hydrogen bond bridging. At the same time, the silanol is dehydrogenated under alkaline conditions to form a Lewis base, which continues to react with other silicon nuclei and dehydrates (or dealcoholizes) to polymerize, slowly generating a network structure, and finally forming a SiO2 film on the surface of the cadmium-doped Fe3O4 magnetic particles.

[0036] See attached Figure 1 The energy spectrum of the cadmium-doped Fe3O4 magnetic particles-SiO2 exists in a core-shell form, wherein the cadmium-doped Fe3O4 is the core with a size of 54nm and the silicon oxide is the shell with a size of 26nm. The magnetic nanoparticles are highly uniformly dispersed in the coating without obvious agglomeration. Figure 2 .

[0037] Beneficial technical effects

[0038] (1) The present invention first prepares relatively corrosion-resistant cadmium-doped Fe3O4 magnetic particles, and then effectively purifies the components of the magnetic particles through an acid washing and activation step, while simultaneously introducing hydroxyl groups on their surface.

[0039] (2) By introducing hydroxyl groups in a targeted manner, a slightly spiny silicon oxide coating is coated on the surface of the magnetic particle filler, which can significantly increase the (Cd-Fe)O x @SiO2 filler is soluble in water and is highly dispersed in the polyurethane coating. It has good coating compatibility and significantly improves the physical and chemical properties of polyurethane, such as tensile strength.

[0040] (3) By introducing hydroxyl groups in a targeted manner, a slightly spiny silicon oxide coating is coated on the surface of the magnetic particle filler, which improves the (Cd-Fe)O x The chemical stability of the coating is improved, especially the corrosion resistance of the coating is improved, and the service life of the magnetic coating is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Attachment Figure 1 (Cd-Fe)O x @Energy spectrum of SiO2 filler.

[0042] Attachment Figure 2 (Cd-Fe)O x @Dispersion diagram of SiO2 filler in polyurethane. DETAILED DESCRIPTION Example 1

[0043] A method for preparing a two-component water-based paint filler comprises the following steps:

[0044] (1) Add 6.5mM FeCl3. 6H2O, 0.75 mM CdCl2 . 6H2O metal salt was added to an ethanol-deionized water solution with a volume ratio of ethanol to deionized water of 1:8. After stirring evenly, 3.5 g / L tetrahydroxypropylethylenediamine and 1.5 g / L ethylenediaminetetraacetic acid complexing agent were added in sequence. 0.03 g / L 2,2'-bipyridine was then added as a stabilizer and 12.5 mL NaBH4 was added as a reducing agent. After stirring evenly, sodium acetate was used as an alkaline source and the pH was adjusted to 8 to obtain a precursor solution.

[0045] (2) Place the above precursor solution in an unlined stainless steel hydrothermal reactor, use nitrogen to expel the air in the reactor, then seal the reactor, heat it to 305°C at 7.5°C / min, keep it at that temperature for 36 hours, and cool it naturally to room temperature;

[0046] (3) Magnetic separation of hydrothermal products and activation and acid washing purification: the activation and acid washing purification is to place the magnetic separation hydrothermal products in a mixed solution of 98wt.% H2SO4 and 30wt.% H2O2 with a volume ratio of 1.5:1 for 2.5 minutes at a temperature of 30°C and stirring with a motor. After activation and acid washing purification, the magnetic particles are repeatedly washed with deionized water and ethanol in sequence until neutral. The saturation magnetic intensity of the magnetic particles after activation and acid washing purification is 62.7 emu / g, the remanence is 4.23emu / g, and the coercive force is Hc=41.8G. A 15wt.% magnetic particle suspension is prepared. The solvent of the suspension is composed of 4.5wt.% polyether modified silicone wetting agent, ethanol and deionized water, and the volume ratio of ethanol to deionized water is 1:8.

[0047] (4) Add 6.5 mL of ammonia water to the magnetic particle suspension prepared in step (3), stir for 15 min, add 3.5 g of ethyl silicate, stir for 13 h with a motor at 12 °C, then filter, wash, and vacuum dry the product to obtain (Cd-Fe)O x @SiO2 filler,(Cd-Fe)O x The saturation magnetic intensity of SiO2 filler is 25.3 emu / g.

[0048] The (Cd-Fe)O x @SiO2 filler is ultrasonically dispersed in deionized water containing a wetting agent, (Cd-Fe)O x @The mass concentration of SiO2 is 45wt%, the mass concentration of the wetting agent is 1.5wt.%, and the filler suspension obtained.

[0049] Comparative Example 1

[0050] A method for preparing a two-component water-based paint filler comprises the following steps:

[0051] (1) 6.5 mM FeCl3 . 6H2O, 0.75 mM CdCl2 . 6H2O metal salts were added into an ethanol-deionized water solution with a volume ratio of 1:8, and after stirring evenly, 5 g / L tetrahydroxypropyl ethylenediamine and 12.5 mL NaBH4 as a reducing agent were added in turn, and after stirring evenly, sodium acetate was used as an alkali source to adjust the pH to 8 to obtain a precursor solution.

[0052] (2) The precursor solution was placed in a stainless steel autoclave without a liner, nitrogen was used to expel the air in the autoclave, and then the autoclave was sealed, and the temperature was raised to 230°C at a rate of 7.5°C / min, and then the temperature was maintained for 36 h, and then the temperature was naturally cooled to room temperature.

[0053] (3) The hydrothermal product was magnetically separated and activated and acid washed for purification: the magnetically separated hydrothermal product was placed in a mixed solution of 98 wt.% H2SO4 and 30 wt.% H2O2 with a volume ratio of 1.5:1, and treated for 2.5 min at a temperature of 30°C, and stirred with a motor, and after the activated acid washing and purification, deionized water and ethanol were used to repeatedly clean in turn until neutral, and a 15 wt.% magnetic particle suspension was prepared, and the solvent of the suspension was composed of 4.5 wt.% polyether-modified silicone wetting agent, ethanol and deionized water, and the volume ratio of ethanol and deionized water was 1:8.

[0054] (4) 6.5 mL of ammonia water was added to the magnetic particle suspension prepared in step (3), stirred for 15 min, 3.5 g of ethyl silicate was added, and stirred with a motor for 13 h at a temperature of 12°C, and then the product was filtered and washed, and vacuum dried to obtain (Cd-Fe)O x @SiO2 filler.

[0055] The (Cd-Fe)O x @SiO2 filler was ultrasonically dispersed in deionized water containing a wetting agent, and the mass concentration of (Cd-Fe)O x @SiO2 was 45 wt%, and the mass concentration of the wetting agent was 1.5 wt.%.

[0056] Comparative Example 2

[0057] A method for preparing a two-component water-based coating filler, comprising the following steps:

[0058] (1) 6.5 mM FeCl3 .6H2O, metal salt is added into ethanol-deionized water solution, the volume ratio of ethanol and deionized water is 1:8, after stirring uniformly, 3.5 g / L tetrahydroxypropyl ethylenediamine, 1.5 g / L ethylenediaminetetraacetic acid complexing agent are added in turn, then 0.03 g / L 2,2'-dipyridyl is added as stabilizer, 12.5 mL NaBH4 is added as reducing agent, after stirring uniformly, sodium acetate is added as alkali source, and pH is adjusted to 8 to obtain a precursor solution.

[0059] (2) The precursor solution is placed in a stainless steel autoclave without lining, nitrogen is used to discharge air in the autoclave, then the autoclave is sealed, and the temperature is increased to 305°C at a speed of 7.5°C / min, and the temperature is kept for 36 h, and then the temperature is naturally cooled to room temperature.

[0060] (3) The hydrothermal product is magnetically separated and activated and acid washed and purified: the magnetically separated hydrothermal product is placed in a mixed solution of 98 wt.% H2SO4 and 30 wt.% H2O2 with a volume ratio of 1.5:1, and is treated for 2.5 min at a temperature of 30°C under motor stirring, and after the activated and acid washed and purified, the product is repeatedly cleaned to neutral with deionized water and ethanol in turn, a 15 wt.% magnetic particle suspension is prepared, and the solvent of the suspension is composed of 4.5 wt.% polyether modified silicone wetting agent, ethanol and deionized water, and the volume ratio of ethanol and deionized water is 1:8.

[0061] (4) 6.5 mL of ammonia water is added to the magnetic particle suspension prepared in step (3), and stirred for 15 min, 3.5 g of ethyl silicate is added, and the product is stirred by a motor for 13 h at a temperature of 12°C, and then the product is filtered and washed, and vacuum dried to obtain a (Cd-Fe)O x @SiO2 filler.

[0062] The (Cd-Fe)O x @SiO2 filler is ultrasonically dispersed in deionized water containing a wetting agent, the mass concentration of the (Cd-Fe)O x @SiO2 is 45 wt%, and the mass concentration of the wetting agent is 1.5 wt.%.

[0063] Comparative Example 3

[0064] A method for preparing a two-component water-based coating filler, comprising the following steps:

[0065] (1) 6.5 mM FeCl3 . 6H2O, 0.75 mM CdCl2 .6H2O metal salt is added to an ethanol-deionized water solution with a volume ratio of 1:8, and then 3.5 g / L tetrahydroxypropyl ethylenediamine, 1.5 g / L ethylenediaminetetraacetic acid complexing agent, 0.03 g / L 2,2'-dipyridyl as stabilizer, and 12.5 mL NaBH4 as reducing agent are added in sequence. After stirring, sodium acetate is added as alkali source to adjust pH to 8 to obtain a precursor solution.

[0066] (2) The precursor solution is placed in a stainless steel autoclave without lining, and nitrogen is used to remove air in the autoclave. Then the autoclave is sealed, heated to 305°C at a rate of 7.5°C / min, and kept for 36 h, and then naturally cooled to room temperature.

[0067] (3) The hydrothermal product is magnetically separated, and a 15 wt.% magnetic particle suspension is prepared, and the solvent of the suspension is composed of 4.5 wt.% polyether-modified silicone wetting agent, ethanol and deionized water with a volume ratio of 1:8.

[0068] (4) 6.5 mL of ammonia water is added to the magnetic particle suspension prepared in step (3) and stirred for 15 min, and then 3.5 g of ethyl silicate is added, and the product is stirred by an electric motor for 13 h at a temperature of 12°C. Then the product is filtered and washed, and vacuum dried to obtain a (Cd-Fe)O x @SiO2 filler.

[0069] The (Cd-Fe)O x @SiO2 filler is ultrasonically dispersed in deionized water containing a wetting agent, and the mass concentration of (Cd-Fe)O x @SiO2 is 45 wt%, and the mass concentration of the wetting agent is 1.5 wt.% to obtain a filler suspension.

[0070] The preparation processes of Example 1 and Comparative Examples 1-3 are substantially the same, the main difference is that there is no complexing agent and stabilizer in Comparative Example 1, no cadmium salt in Comparative Example 2, and no activation step in Comparative Example 3. After the magnetic separation of the hydrothermal products in step (3) of Example 1 and Comparative Examples 1-3 is dried in vacuum, corrosion tests are carried out. Equal amounts of samples are immersed in a 5wt.% salt solution for 15 minutes, and the corrosion rates of Example 1 and Comparative Examples 1-3 are 93.5wt.%, 78.5wt.%, 80.2wt.%, and 93.4wt.% respectively. The corrosion efficiency is further tested for 30 minutes, and the corrosion rates of Example 1 and Comparative Examples 1-3 are 91.2wt.%, 65.5wt.%, 66.2wt.%, and 91.3wt.% respectively. The corrosion rate of Example 1 at 15 minutes and 30 minutes is not substantially different, which clearly proves that the product is a corrosion-resistant magnetic particle. The corrosion resistance of the magnetism is derived from the cadmium doping under high-temperature and high-pressure hydrothermal conditions. Under the same conditions, the corrosion efficiency is higher in Comparative Example 1 without adding a complexing agent and a stabilizer and at a lower hydrothermal temperature, which is attributed to the absence of alloy formation, and the corrosion is caused by iron oxide and cadmium oxide, and the effect is similar to that of Comparative Example 2 without adding a cadmium salt. In addition, there is no substantial difference between Comparative Example 3 and Example 1 because the treatment steps before activation are similar. Example 2

[0071] The suspension prepared from Example 1 and Comparative Example 3 is used as a filler for polyurethane.

[0072] A preparation method of a two-component water-based paint,

[0073] (A) Preparation method of Component A: After the water-based hydroxyl acrylate resin, wetting dispersant, defoaming agent, leveling agent, deionized water are stirred uniformly according to the formulation amount, the filler suspension is added and stirred uniformly at 1000 rpm, and then the cosolvent and thixotropic thickener are added and stirred uniformly at 700 rpm.

[0074] (B) Preparation method of Component B: The hydrophilic modified isocyanate curing agent is fully mixed with propylene glycol diacetate to obtain.

[0075] (C) When used, Component A and Component B are mixed uniformly according to a mass ratio of (7.5):1, and then sprayed on the surface of the substrate. Example 3

[0076] A water-based two-component polyurethane paint, comprising Component A and Component B; the mass ratio of the A component and the B component is 7.5:1.

[0077] The A part includes the following components in parts by mass: aqueous hydroxyl acrylic resin 52 parts, wetting dispersant 1.5 parts, defoamer 1.5 parts, co-solvent 7.5 parts, filler suspension 20 parts, leveling agent 1.5 parts, thixotropic thickener 2.5 parts, deionized water 20 parts;

[0078] The B part includes the following components in parts by mass: hydrophilically modified isocyanate curing agent 70 parts, propylene glycol diacetate 12.5 parts.

[0079] The wetting dispersant is selected from BYK-190.

[0080] The defoamer is selected from BYK 093.

[0081] The co-solvent is selected from ethylene glycol butyl ether.

[0082] The leveling agent is selected from TEGO Glide 4100.

[0083] The thixotropic thickener is selected from RHEOLATE 299.

[0084] The suspension prepared in Example 1 is a filler for polyurethane.

[0085] Comparative Example 4

[0086] An aqueous two-component polyurethane coating includes an A part and a B part; the mass ratio of the A part and the B part is 7.5:1.

[0087] The A part includes the following components in parts by mass: aqueous hydroxyl acrylic resin 52 parts, wetting dispersant 1.5 parts, defoamer 1.5 parts, co-solvent 7.5 parts, filler suspension 20 parts, leveling agent 1.5 parts, thixotropic thickener 2.5 parts, deionized water 20 parts;

[0088] The B part includes the following components in parts by mass: hydrophilically modified isocyanate curing agent 70 parts, propylene glycol diacetate 12.5 parts.

[0089] The wetting dispersant is selected from BYK-190.

[0090] The defoamer is selected from BYK 093.

[0091] The co-solvent is selected from ethylene glycol butyl ether.

[0092] The leveling agent is selected from TEGO Glide 4100.

[0093] The thixotropic thickener is selected from RHEOLATE 299.

[0094] The suspension prepared in Comparative Example 3 is a filler for polyurethane.

[0095] Comparative Example 5

[0096] An aqueous two-component polyurethane coating, comprising an A component and a B component; the mass ratio of the A component and the B component is (7.5):1.

[0097] The A component comprises the following components by mass fraction: an aqueous hydroxyl acrylic resin 52 parts, a wet dispersant 1.5 parts, an antifoaming agent 1.5 parts, a cosolvent 7.5 parts, a filler suspension 20 parts, a leveling agent 1.5 parts, a thixotropic thickening agent 2.5 parts, deionized water 20 parts;

[0098] The B component comprises the following components by mass fraction: a hydrophilic modified isocyanate curing agent 70 parts, propylene glycol diacetate 12.5 parts.

[0099] The wet dispersant is selected from BYK-190.

[0100] The antifoaming agent is selected from BYK093.

[0101] The cosolvent is selected from ethylene glycol butyl ether.

[0102] The leveling agent is selected from TEGO Glide 4100.

[0103] The thixotropic thickening agent is selected from RHEOLATE 299.

[0104] The filler suspension is prepared as follows: comprising the following steps:

[0105] (1) 6.5 mM FeCl3 . 6H2O, 0.75 mM CdCl2 . 6H2O metal salts are added to an ethanol-deionized water solution, the volume ratio of ethanol and deionized water is 1:8, after stirring uniformly, 3.5 g / L tetrahydroxypropyl ethylenediamine, 1.5 g / L ethylenediaminetetraacetic acid complexing agent are added in turn, then 0.03 g / L 2,2'-dipyridyl is added as a stabilizer, 12.5 mL NaBH4 is added as a reducing agent, stirring uniformly, then sodium acetate is used as an alkali source to adjust pH=8, to obtain a precursor solution;

[0106] (2) The precursor solution is placed in a stainless steel hydrothermal reaction kettle without lining, nitrogen is used to discharge the air in the reaction kettle, then the reaction kettle is sealed, heated to 305℃ at 7.5℃ / min, and kept for 36 h, and then naturally cooled to room temperature;

[0107] (3) Magnetic separation of the hydrothermal product, and activation acid washing purification: the activation acid washing purification is that the magnetic separation of the hydrothermal product is placed in a mixed solution of 98 wt.% H2SO4 and 30 wt.% H2O2 with a volume ratio of 1.5:1 for 2.5 min at a temperature of 30°C, and motor stirring, and after the activation acid washing purification, the product is repeatedly cleaned with deionized water and ethanol in sequence until neutral.

[0108] The (Cd-Fe)O x The filler is ultrasonically dispersed in deionized water containing a wetting agent, the mass concentration of the (Cd-Fe)O is 45 wt%, and the mass concentration of the wetting agent is 1.5 wt.% to obtain a filler suspension.

[0109]

[0110] As shown in the above table, the main difference between Example 3 and Comparative Example 4 is whether the filler is different, and the further difference is whether the filler is subjected to a purification and activation treatment, and the difference between Example 3 and Comparative Example 5 is whether a coating treatment is performed. The coating is coated on the surface of a metal substrate, and then a polarization potential test is performed, and a corrosion current density is converted, and the corrosion current density of Example 3 is obviously higher in order of magnitude than that of Comparative Example 4 and Comparative Example 5. The main difference between Comparative Example 5 is whether it is subjected to a purification and activation treatment, and the non-purification and activation treatment results in a hydrothermal product with a relatively mixed composition, and more importantly, the surface has no functional group, which affects the subsequent directional coating of silicon oxide. In addition, as shown in Comparative Example 5, without silicon oxide coating, the (Cd-Fe)O x The filler has poor corrosion resistance, and the (Cd-Fe)O x The dispersion in the coating is poor, and the filler is aggregated, which will affect the corrosion resistance of the coating, and the most direct manifestation of the aggregation is the decrease of the tensile strength, as shown above.

[0111] The above-described examples have described the technical solutions of the present application in detail, and it should be understood that the above-described only is the specific embodiments of the present application, and is not used to limit the present application, and any modification and improvement made within the principle range of the present application should be included in the protection range of the present application.

Claims

1. A method for preparing a two-component water-based paint filler, characterized in that The steps include: (1) Add 5-8mM FeCl3 . 6H2O, 0.5-1 mM CdCl2 . 6H2O metal salt is added to an ethanol-deionized water solution, stirred evenly, and then 3-4 g / L tetrahydroxypropylethylenediamine and 1-2 g / L ethylenediaminetetraacetic acid composite complexing agent are added in sequence. Then, 0.02-0.04 g / L 2,2'-bipyridine is added as a stabilizer and 10-15 mL NaBH4 is added as a reducing agent. After stirring evenly, sodium acetate is used as an alkaline source and the pH is adjusted to 7.5-8.5 to obtain a precursor solution. (2) Place the above-mentioned precursor solution in an unlined stainless steel hydrothermal reactor, use nitrogen to expel the air in the reactor, then seal the reactor, heat it to 300-310°C at 5-10°C / min, keep it at this temperature for 24-48 hours, and cool it naturally to room temperature; (3) Magnetic separation of hydrothermal products and activation and acid washing purification: the activation and acid washing purification is to place the magnetic separation hydrothermal products in a mixed solution consisting of 98wt.% H2SO4 and 30wt.% H2O2 with a volume ratio of 1-2:1 for 2-3 minutes at a temperature of 30°C and stirring with a motor. After activation and acid washing purification, deionized water and ethanol are used to repeatedly wash the products until they are neutral, and a 10-20wt.% magnetic particle suspension is prepared. The solvent of the suspension consists of a polyether-modified silicone wetting agent, ethanol and deionized water. (4) Add ammonia water to the magnetic particle suspension prepared in step (3), stir for 10-20 minutes, add ethyl silicate, stir with a motor for 12-14 hours at a temperature of 10-14°C, then filter, wash, and vacuum dry the product to obtain (Cd-Fe)O x @SiO2 filler, the content of the polyether modified silicone wetting agent is 4-5wt.%.

2. A method for preparing a two-component water-based paint filler according to claim 1, characterized in that The volume ratio of ethanol to deionized water in step (1) and step (3) is 1:7-9.

3. A method for preparing a two-component water-based paint filler according to claim 1, characterized in that The amount of the ethyl silicate used is 3-4 g, and the amount of the ammonia water used is 5-8 mL.

4. A method for preparing a two-component water-based paint filler according to claim 1, characterized in that (Cd-Fe)O x The core size is 20-70 nm, and the thickness of the SiO2 shell is 10-30 nm.

5. A two-component water-based paint filler, characterized in that The method for preparing a two-component water-based paint filler is used.

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