Anti-aging rare earth environment-friendly pigment and application process thereof

Abstract

The invention relates to the technical field of environment-friendly pigments, in particular to an anti-aging rare-earth environment-friendly pigment and an application process thereof.The anti-aging rare-earth environment-friendly pigment is prepared by taking wide-band gap aluminosilicate as a matrix, performing bifunctional modification treatment and then compounding with modified kaolin; preparing a doping solution by adopting a gradient rare earth doping mode, mixing the doping solution with the composite matrix to form slurry, and adding a surfactant and an anti-aging additive for modification; and drying, heating and roasting in stages, crushing and screening to obtain the finished product pigment. Mixing the pigment with a base material, a dispersing agent, a coalescing agent and the like to prepare a coating, coating the surface of a base material with the coating, and curing to form a film; the preparation method is controllable in process, the obtained pigment is good in environmental protection property, and the comprehensive performance of a coating can be improved after the pigment is applied to paint. The product is free of harmful heavy metal, environment-friendly, up to standard, excellent in anti-aging performance, good in dispersion stability and free of layering during storage; the coating is outstanding in mechanical property and corrosion inhibition effect and strong in adhesive force.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environment-friendly pigments, in particular to an anti-aging rare earth environment-friendly pigment and an application process thereof. BACKGROUND

[0002] The rare earth environment-friendly pigment has excellent coloring performance, thermal stability and environmental protection characteristics, and becomes an important functional filler for replacing traditional heavy metal pigments in the C09D coating system, and is widely used in the fields of building, industrial corrosion prevention and automobile coating. The unique electronic structure of rare earth ions makes them have good absorption capacity for ultraviolet rays, which can effectively improve the weathering resistance of the coating layer. Silicate and aluminate substrates are often used as carriers for rare earth pigments because of their wide sources and stable structure. However, the existing rare earth environment-friendly pigments still have many technical shortcomings in component design, structure control and preparation process, which are difficult to meet the application requirements of high-performance coatings.

[0003] In the prior art, the silicate and aluminate substrate of the rare earth pigment is mostly unmodified natural mineral, which has few types and low content of surface functional groups, and has weak binding force with rare earth ions, which leads to easy aggregation of rare earth ions, reduces the utilization rate of rare earth, and affects the dispersibility and coloring power of the pigment. The rare earth doping method is mostly simple physical mixing or co-precipitation, without ion-level structure design, narrow ultraviolet absorption band, limited thermal stability range, and unable to maximize the anti-aging performance. At the same time, the existing modifiers such as part of the silane coupling agent and the surfactant have the problem of high volatile organic content, and the modification of kaolin mostly uses single calcination treatment, which has limited specific surface area improvement, and is difficult to effectively improve the interface compatibility of the pigment and the coating base material.

[0004] The selection of anti-aging additives also has obvious deficiencies, mostly single-component antioxidants or light stabilizers, lacking of synergistic effect design, single anti-aging effect, and unable to resist the dual effects of thermal oxidation and ultraviolet aging. In addition, in the existing preparation process, the chelation conditions of the rare earth doping liquid are not properly controlled, the coordination reaction is not sufficient, and the heating rate and temperature parameters in the calcination process are not reasonably designed, which easily causes the loss of rare earth ions, reduces the storage stability of the pigment, and easily causes the separation and precipitation in the coating system. In summary, the defects of the existing rare earth environment-friendly pigment in environmental protection, anti-aging performance, structure stability and application compatibility limit its popularization and application in the field of high-end coatings. Therefore, it is an urgent technical problem in the industry to develop a rare earth pigment with reasonable structure design, excellent environmental protection and outstanding anti-aging performance and a matching application process. SUMMARY

[0005] (I)Technical problems solved In view of the deficiencies of the prior art, the present application provides an anti-aging rare earth environment-friendly pigment and an application process thereof.

[0006] (II)Technical solutions An anti-aging rare earth environment-friendly pigment is prepared from the following components by weight: a wide-bandgap silico-aluminate matrix modified by a hydroxyl-carboxyl bifunctional group in an amount of 45-65 parts, lanthanum-yttrium gradient-doped rare earth complex ions in an amount of 8-15 parts, kaolin modified by silane coupling agent KH550 in an amount of 10-20 parts, alkyl polyglycoside type environment-friendly surfactant in an amount of 0.5-2 parts, and a ternary anti-aging additive in an amount of 3-8 parts. The wide-bandgap silico-aluminate matrix modified by a hydroxyl-carboxyl bifunctional group is an Al2O2·2SiO2·2H2O crystal type silico-aluminate modified by grafting maleic anhydride and ethylene glycol bisglycidyl ether, with a hydroxyl grafting amount of 0.8-1.5 mmol / g, a carboxyl grafting amount of 0.5-1.0 mmol / g, and a particle size of 50-200 nm. In the lanthanum-yttrium gradient-doped rare earth complex ions, lanthanum ions are the core layer, yttrium ions are the outer layer, and the weight ratio of the core layer to the outer layer is 1:1-1:1.5. The ternary anti-aging additive is a complex of a hindered phenolic antioxidant, a phosphite auxiliary antioxidant, and a benzotriazole light stabilizer, with a weight ratio of 3:1:1-4:1:1. 3+ , Ce 4+ , and Y 3+ , Er 3+ .

[0007] Preferably, the lanthanum ions are a complex of lanthanum nitrate and cerium nitrate, with a weight ratio of 2:1-3:1; and the yttrium ions are a complex of yttrium nitrate and erbium nitrate, with a weight ratio of 3:1-4:1.

[0008] Preferably, the kaolin modified by silane coupling agent KH550 is prepared by calcining kaolin at 800-900°C for 2-3 h, mixing with a 5%-8% KH550 ethanol solution at a weight ratio of 10:1 after cooling, stirring at 60-70°C for 2-3 h, filtering, drying, and crushing to pass through a 300-400 mesh sieve. The specific surface area of the modified kaolin is 35-50 m 2 / g.

[0009] Preferably, the alkyl polyglycoside type environment-friendly surfactant is APG12-14 type alkyl polyglycoside, with a hydrophilic-lipophilic balance value of 12-14 and an adsorption amount in the pigment system of 1.2-2.0 mg / g.

[0010] Preferably, in the ternary anti-aging additive, the hindered phenolic antioxidant is antioxidant 1010, the phosphite auxiliary antioxidant is antioxidant 168, and the benzotriazole light stabilizer is light stabilizer UV-327.

[0011] Preferably, the Al2O3·2SiO2·2H2O crystal form silico-aluminate has a hydroxyl grafting amount of 0.8-1.5 mmol / g, a carboxyl grafting amount of 0.5-1.0 mmol / g, and a particle size of 50-200 nm.

[0012] Preferably, the preparation process of the anti-aging rare earth environment-friendly pigment comprises the following steps: S1, preparation of a bifunctional substrate: place a wide-bandgap silico-aluminate substrate in a high-speed mixer, add a compound modifier of maleic anhydride and ethylene glycol bisglycidyl ether, the modifier is added in an amount of 5%-8% of the weight of the silico-aluminate substrate, mix and react at 120-150°C and a rotation speed of 800-1200 r / min for 1-2 h, cool to room temperature, crush, and sieve through a 300-400 mesh sieve to obtain a silico-aluminate substrate modified by a hydroxyl-carboxyl bifunctional group; S2, preparation of a gradient rare earth doping solution: weigh lanthanide salts and yttrium salts according to the weight ratio of the core layer to the outer layer, dissolve the lanthanide salts in deionized water to prepare a core layer solution with a mass concentration of 10%-12%, then dissolve the yttrium salts in the core layer solution to prepare a gradient doping solution with a mass concentration of 12%-15%, add a citric acid chelating agent, the chelating agent is added in an amount of 6%-8% of the total weight of the rare earth salts, stir and chelate in a 55-60°C water bath for 45-50 min, adjust the pH value to 5.0-6.0, and obtain a rare earth doping solution; S3, compound modification mixing: add the bifunctional modified substrate and silane coupling agent modified kaolin to a conical mixer, pre-mix at a rotation speed of 1000-1500 r / min for 20-25 min, then slowly drop the rare earth doping solution at a rate of 1-2 mL / min, continue mixing for 35-40 min after the dropping is completed, and obtain a mixed slurry with a solid content of 40%-50%; S4, surface modification and anti-aging modification: add alkyl polyglycoside surfactant and a ternary anti-aging additive to the mixed slurry, stir and react at 85-90°C and a rotation speed of 600-800 r / min for 70-90 min, detect the pH value every 15 min during the stirring and reaction, and maintain the pH value at 6.8-7.2; S5, drying and sintering: place the modified slurry in a spray dryer, control the inlet temperature at 185-195°C and the outlet temperature at 85-90°C, dry to obtain precursor powder with a particle size of 10-20 μm, place the precursor powder in a muffle furnace, heat to 400-500°C at a heating rate of 6-8°C / min, maintain the temperature for 1 h, then heat to 650-700°C at a heating rate of 3-5°C / min, sinter for 2-2.5 h, naturally cool to room temperature, crush by an air flow crusher, sieve through a 500-600 mesh sieve, and obtain the anti-aging rare earth environment-friendly pigment.

[0013] Preferably, the lanthanide series salt in step S2 is lanthanum nitrate with a purity of ≥ 99.9%, cerium nitrate with a purity of ≥ 99.5%, both of which are used in a weight ratio of 2:1, and the coordination molar ratio of the lanthanide series salt to the citric acid chelating agent is 1:1.4; the yttrium series salt is yttrium nitrate with a purity of ≥ 99.9%, erbium nitrate with a purity of ≥ 99.5%, both of which are used in a weight ratio of 3:1, and the coordination molar ratio of the yttrium series salt to the citric acid chelating agent is 1:1.3; and the crushing pressure of the jet mill in step S5 is 0.6-0.8 MPa.

[0014] Preferably, the application process of the anti-aging rare earth environment-friendly pigment in the coating comprises the following steps: S1, pigment dispersion treatment: the anti-aging rare earth environment-friendly pigment is mixed with the coating base material in a weight ratio of 1:6-1:9, a polycarboxylate dispersant is added, the amount of the dispersant added is 1.5%-2.5% of the weight of the pigment, it is first pre-dispersed in a high-speed dispersion machine at a rotating speed of 2500-3000 r / min for 20-25 min, and then it is transferred into a sand mill, zirconium beads are used as the grinding medium, the filling rate of the grinding medium is 70%-75%, and the grinding rotating speed is 1800-2200 r / min, until the pigment particle size D90 is ≤100 nm, and a pigment color paste is obtained; S2, environment-friendly coating preparation: alcohol ester twelve film-forming additives and hydroxyethyl cellulose thickening agents are added to the pigment color paste, the amount of the film-forming additives added is 2%-4% of the weight of the coating base material, the amount of the thickening agents added is 0.3%-0.5% of the weight of the coating base material, and the mixture is stirred and mixed at a rotating speed of 500-800 r / min for 15-20 min, deionized water is used to adjust the coating viscosity to 55-75 KU and the pH value to 7.0-8.0, and a rare earth environment-friendly coating is obtained; S3, coating and curing film formation: the rare earth environment-friendly coating is coated on the surface of a substrate by using an air spraying method, the spraying pressure is 0.3-0.5 MPa, the dry film thickness of the coating is 35-45 μm, the coating is pre-dried at 25°C and under the condition of a relative humidity of 50%-60% for 40-50 min, and then it is baked and cured in a hot air oven at 65-75°C for 1.5-2 h, and it is naturally cooled to room temperature, and an anti-aging coating is obtained.

[0015] Preferably, the coating base material in step S1 is at least one of pure acrylic emulsion and epoxy resin E-44; and the substrate in step S3 is a phosphating-treated cold-rolled steel plate or a polycarbonate plate, and the film weight of the phosphating treatment is 1.5-2.0 g / m 2 .

[0016] (Three)Beneficial technical effects Compared with the prior art, the beneficial effects of the present application are: 1. The silico-aluminate base modified by hydroxyl-carboxyl bifunctional groups provides stable coordination binding sites for rare earth ions, effectively solving the problems of rare earth ion agglomeration and loss, and improving the structural stability of the pigment. The design of lanthanum-yttrium gradient-doped rare earth composite ions realizes the widening of the ultraviolet absorption band and the enhancement of the absorption effect, and the kaolin modified by silane coupling agent greatly improves the dispersibility of the pigment and enhances the interface compatibility with the coating base, solving the problems of poor dispersibility and poor combination with the base of the existing pigment.

[0017] 2. The pigment of the present application does not contain lead, cadmium, mercury, hexavalent chromium and other banned heavy metals, and the selected surfactants and anti-aging additives are all environmentally friendly components, without the release of volatile organic compounds, meeting the environmental protection policy requirements of the current coating industry, and avoiding the environmental protection hidden dangers of traditional pigments from the source. In terms of anti-aging performance, the compounding system of ternary anti-aging additives realizes the synergistic effect of anti-oxidation and anti-ultraviolet, and compared with single-component additives, the anti-aging effect is significantly improved, which can effectively delay the aging, discoloration and pulverization of the coating layer during use, and prolong the service life of the coating layer.

[0018] 3. The step-by-step base modification, gradient doping liquid preparation and composite modification process has scientific and reasonable parameters, which not only improves the doping efficiency and binding stability of rare earth ions, but also reduces the raw material loss in the production process, and is easy to industrialize and scale up. The coloring power and storage stability of the pigment of the present application are excellent, and the adaptability to the coating base is strong, the coating layer after coating and curing has good film forming property, outstanding anti-aging and scrubbing resistance, and wide applicable substrate range, which can meet the demand of different fields such as building and industrial corrosion resistance for high-performance environmental protection coating, and has good market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a preparation process flow chart of the anti-aging rare earth environmental protection pigment disclosed by the present application; Figure 2 is a VOC content and fold line comparison chart of the examples and comparative examples; Figure 3 is a 1000h xenon lamp aging gloss retention rate and pigment particle size columnar comparison chart of the examples and comparative examples; Figure 4 is a radar comparison chart of the performance comparison data of the examples and comparative examples after unified dimensioning. DETAILED DESCRIPTION

[0020] The technical solutions of the present application will be further described and explained by specific embodiments in combination with the drawings.

[0021] I. Experimental raw material preparation (I) Basic raw materials The wide-bandgap aluminosilicate matrix modified with hydroxyl-carboxyl bifunctional groups has a hydroxyl grafting amount of 1.2 mmol / g, a carboxyl grafting amount of 0.8 mmol / g, and a particle size of 120 nm. Lanthanum nitrate has a purity of not less than 99.9%; cerium nitrate has a purity of not less than 99.5%; yttrium nitrate has a purity of not less than 99.9%; erbium nitrate has a purity of not less than 99.5%. Industrial-grade kaolin with a particle size not exceeding 5μm; Silane coupling agent KH550 has an industrial grade purity of not less than 98%; Anhydrous ethanol (analytical grade); maleic anhydride (analytical grade); Ethylene glycol diglycidyl ether (analytical grade); Citric acid (analytical grade) chelating agent; APG12-14 alkyl polysaccharide has a hydrophilic-lipophilic balance value of 13 and an adsorption capacity of 1.6 mg / g. Antioxidant 1010, hindered phenols; Antioxidant 168, phosphites; Light stabilizer UV-327 (benzotriazole class); Polycarboxylate dispersants, industrial grade; Alcohol ester dodecyl film-forming aid, industrial grade; Hydroxyethyl cellulose thickener, industrial grade; Pure acrylic emulsion with a solid content of 50%; epoxy resin E-44, industrial grade; The phosphated cold-rolled steel sheet has a phosphate coating weight of 1.8 g / m². 2 ; Polycarbonate sheet thickness 2mm; Deionized water.

[0022] (II) Experimental Equipment High-speed mixers, cone mixers, spray dryers, muffle furnaces, air jet mills, high-speed dispersers, sand mills, air spraying equipment, precision pH meters, laser particle size analyzers, specific surface area analyzers, Zeta potentiometers, aging test chambers, and scrub resistance testers.

[0023] II. Example 1 (I) Preparation of anti-aging rare earth environmentally friendly pigments Preparation of the bifunctional matrix: 55 parts of wide-bandgap aluminosilicate matrix were weighed and placed in a high-speed mixer. A compound modifier, weighing 6% by weight of the aluminosilicate matrix, was added. The mass ratio of maleic anhydride to ethylene glycol diglycidyl ether in the compound modifier was 1:1. The mixer temperature was set to 135℃ and the rotation speed to 1000 r / min, and the reaction was carried out for 1.5 h. After the reaction, the mixture was cooled to room temperature, pulverized using a universal pulverizer, and passed through a 350-mesh standard sieve to obtain a hydroxyl-carboxyl bifunctional modified aluminosilicate matrix. The hydroxyl grafting amount was 1.1 mmol / g, the carboxyl grafting amount was 0.7 mmol / g, and the particle size was 110 nm.

[0024] Preparation of gradient rare earth doped solution: Lanthanide salts and yttrium salts were weighed at a core-to-outer-layer weight ratio of 1:1.2, with a total rare earth composite ion content of 12 parts. The weight ratio of lanthanum nitrate to cerium nitrate in the lanthanide salts was 2.5:1, and the weight ratio of yttrium nitrate to erbium nitrate in the yttrium salts was 3.5:1. First, the lanthanide salts were dissolved in deionized water to prepare a core layer solution with a mass concentration of 11%. Then, the yttrium salts were added to the core layer solution, stirred until dissolved, and a gradient doped solution with a mass concentration of 13.5% was prepared. Citric acid chelating agent (7% of the total weight of the rare earth salts) was added to the doped solution, and the mixture was placed in a 58℃ constant temperature water bath. The stirring rate was 300 r / min, and the chelation reaction was carried out for 48 min. During this period, the pH value was adjusted to 5.5 with dilute nitric acid to obtain a stable rare earth doped solution.

[0025] Composite modification and mixing: Weigh 15 parts of kaolin modified with silane coupling agent KH550. The modification method is as follows: calcination of kaolin at 850℃ for 2.5h, cooling, and mixing with a 6.5% KH550 ethanol solution at a weight ratio of 10:1. Stir and react at 65℃ for 2.5h, filter, dry at 80℃ for 4h, pulverize, and pass through a 350-mesh sieve. The specific surface area is measured to be 42m². 2 / g. Modified kaolin and the bifunctional modified matrix prepared in step 1 were added together into a conical mixer, and the speed was set to 1200 r / min for premixing for 22 min. The rare earth doping solution prepared in step 2 was slowly added dropwise to the mixture at a rate of 1.5 mL / min using a peristaltic pump. After the addition was completed, the mixture was continued for 38 min to obtain a mixed slurry with a solid content of 45%.

[0026] Surface modification and anti-aging modification: 1.2 parts of APG12-14 type alkyl polysaccharide surfactant and 5 parts of ternary anti-aging additive were added to the mixed slurry. The weight ratio of antioxidant 1010, antioxidant 168 and light stabilizer UV-327 in the ternary anti-aging additive was 3.5:1:1. The temperature of the mixed system was raised to 88℃, the stirring speed was 700 r / min, and the reaction was carried out for 80 min. During the reaction, the pH value was measured every 15 min with a precision pH meter, and the pH value was maintained at about 7.0 by adding dilute sodium hydroxide solution dropwise.

[0027] Drying and calcination molding: The modified slurry is fed into a spray dryer with an inlet temperature of 190℃ and an outlet temperature of 88℃. After drying, a precursor powder with a particle size of 15μm is obtained. The precursor powder is placed in a muffle furnace and heated to 450℃ at a rate of 7℃ / min under air atmosphere, and held at that temperature for 1 hour; then heated to 680℃ at a rate of 4℃ / min and calcined for 2.2 hours. After naturally cooling to room temperature, it is fed into an air jet mill for pulverization at a pressure of 0.7MPa and passed through a 550-mesh standard sieve to obtain the anti-aging rare earth environmentally friendly pigment product.

[0028] (II) Application in coatings Pigment dispersion treatment: The prepared anti-aging rare earth environmentally friendly pigment was mixed with pure acrylic emulsion at a weight ratio of 1:7.5. 2.0% of the pigment weight of polycarboxylate dispersant was added. The mixture was first pre-dispersed in a high-speed disperser at a speed of 2800 r / min for 23 min. Then it was transferred to a sand mill with zirconium beads as the grinding medium, a filling rate of 72%, and a grinding speed of 2000 r / min. The mixture was continuously ground until the pigment particle size D90=85nm to obtain a uniform pigment paste.

[0029] Environmentally friendly coating preparation: Add 3% by weight of the coating base material of alcohol ester twelve film-forming aid and 0.4% of hydroxyethyl cellulose thickener to the pigment paste, stir and mix at 650 r / min for 18 min, adjust the coating viscosity to 65 KU and the pH value to 7.5 with deionized water to obtain rare earth environmentally friendly coating.

[0030] Coating and curing to form a film: Rare earth environmentally friendly coating is applied to the surface of phosphated cold-rolled steel sheet using air spraying at a pressure of 0.4 MPa, controlling the dry film thickness to 40 μm. The coating is pre-dried at 25℃ and 55% relative humidity for 45 min, then baked and cured in a 70℃ hot air oven for 1.8 h, and naturally cooled to room temperature to obtain an anti-aging coating.

[0031] III. Example 2 (I) Preparation of anti-aging rare earth environmentally friendly pigments Preparation of the bifunctional matrix: 45 parts of wide-bandgap aluminosilicate matrix were weighed and placed in a high-speed mixer. A compound modifier, weighing 5% by weight of the aluminosilicate matrix, was added. The mass ratio of maleic anhydride to ethylene glycol diglycidyl ether in the compound modifier was 1:1. The mixer temperature was set to 120℃ and the rotation speed to 800 r / min, and the reaction was carried out for 1 h. After the reaction, the mixture was cooled to room temperature, pulverized, and passed through a 300-mesh standard sieve to obtain a hydroxyl-carboxyl bifunctional modified aluminosilicate matrix. The hydroxyl grafting amount was 0.8 mmol / g, the carboxyl grafting amount was 0.5 mmol / g, and the particle size was 50 nm.

[0032] Preparation of gradient rare earth doped solution: Lanthanide salts and yttrium salts were weighed at a core-to-outer-layer weight ratio of 1:1, with a total rare earth composite ion content of 8 parts. The weight ratio of lanthanum nitrate to cerium nitrate in the lanthanide salts was 2:1, and the weight ratio of yttrium nitrate to erbium nitrate in the yttrium salts was 3:1. First, the lanthanide salts were dissolved in deionized water to prepare a 10% (w / w) core layer solution. Then, the yttrium salts were added to the core layer solution to prepare a 12% (w / w) gradient doped solution. Citric acid chelating agent (6% of the total weight of the rare earth salts) was added to the doped solution, and the mixture was placed in a 55℃ constant temperature water bath. The stirring rate was 250 r / min, and the chelation reaction was carried out for 45 min. The pH was adjusted to 5.0 with dilute nitric acid to obtain the rare earth doped solution.

[0033] Composite Modification Mixture: Weigh 10 parts of kaolin modified with silane coupling agent KH550. The modification method is as follows: calcination of kaolin at 800℃ for 2 hours, cooling, and mixing with a 5% KH550 ethanol solution at a weight ratio of 10:1. Stirring reaction at 60℃ for 2 hours, filtering, drying at 75℃ for 3 hours, pulverizing, and passing through a 300-mesh sieve. The specific surface area is measured to be 35 m². 2 / g. Modified kaolin and the bifunctional modified matrix prepared in step 1 were added together into a conical mixer, and the speed was set to 1000 r / min for premixing for 20 min. Rare earth dopant solution was added dropwise at a rate of 1 mL / min using a peristaltic pump. After the addition was completed, mixing was continued for 35 min to obtain a mixed slurry with a solid content of 40%.

[0034] Surface modification and anti-aging modification: 0.5 parts of APG12-14 type alkyl polysaccharide surfactant and 3 parts of ternary anti-aging agent were added to the mixed slurry. The weight ratio of antioxidant 1010, antioxidant 168 and light stabilizer UV-327 in the ternary anti-aging agent was 3:1:1. The temperature of the mixing system was raised to 85℃, the stirring speed was 600r / min, and the reaction was carried out for 70min. During the reaction, the pH value was checked every 15min and maintained at about 6.8.

[0035] Drying and calcination molding: The modified slurry is fed into a spray dryer with an inlet temperature of 185℃ and an outlet temperature of 85℃. After drying, a precursor powder with a particle size of 10μm is obtained. The precursor powder is placed in a muffle furnace and heated to 400℃ at a heating rate of 6℃ / min under air atmosphere, and held at that temperature for 1 hour; then heated to 650℃ at a heating rate of 3℃ / min and calcined for 2 hours. After natural cooling, it is pulverized by an air jet mill at a pulverization pressure of 0.6MPa and passed through a 500-mesh standard sieve to obtain the anti-aging rare earth environmentally friendly pigment product.

[0036] (II) Application in coatings Pigment dispersion treatment: The prepared anti-aging rare earth environmentally friendly pigment was mixed with epoxy resin E-44 at a weight ratio of 1:6. 1.5% of the pigment weight of polycarboxylate dispersant was added. The mixture was first pre-dispersed in a high-speed disperser at a speed of 2500 r / min for 20 min, and then transferred to a sand mill with a zircon bead filling rate of 70% and a grinding speed of 1800 r / min. The mixture was ground until the pigment particle size D90=95nm to obtain the pigment paste.

[0037] Environmentally friendly coating preparation: Add 2% by weight of the coating base material of alcohol ester twelve film-forming aid and 0.3% of hydroxyethyl cellulose thickener to the pigment paste, stir and mix at 500 r / min for 15 min, adjust the coating viscosity to 55 KU and the pH value to 7.0 with deionized water to obtain rare earth environmentally friendly coating.

[0038] Coating and curing to form a film: The coating is applied to the surface of the polycarbonate sheet by air spraying at a pressure of 0.3 MPa, resulting in a dry film thickness of 35 μm. The film is pre-dried at 25°C and 50% relative humidity for 40 minutes, then baked and cured in a 65°C hot air oven for 1.5 hours, and allowed to cool naturally to room temperature to obtain the anti-aging coating.

[0039] IV. Example 3 (I) Preparation of anti-aging rare earth environmentally friendly pigments Preparation of the bifunctional matrix: 65 parts of wide-bandgap aluminosilicate matrix were weighed and placed in a high-speed mixer. A compound modifier, weighing 8% by weight of the aluminosilicate matrix, was added. The mass ratio of maleic anhydride to ethylene glycol diglycidyl ether in the compound modifier was 1:1. The mixer temperature was set to 150℃ and the rotation speed to 1200 r / min, and the reaction was carried out for 2 hours. After the reaction, the mixture was cooled to room temperature, pulverized, and passed through a 400-mesh standard sieve to obtain a hydroxyl-carboxyl bifunctional modified aluminosilicate matrix. The hydroxyl grafting amount was 1.5 mmol / g, the carboxyl grafting amount was 1.0 mmol / g, and the particle size was 200 nm.

[0040] Preparation of gradient rare earth doped solution: Lanthanide salts and yttrium salts were weighed at a core-to-outer-layer weight ratio of 1:1.5, with a total rare earth composite ion content of 15 parts. The weight ratio of lanthanum nitrate to cerium nitrate in the lanthanide salts was 3:1, and the weight ratio of yttrium nitrate to erbium nitrate in the yttrium salts was 4:1. First, the lanthanide salts were dissolved in deionized water to prepare a 12% (w / w) core layer solution. Then, the yttrium salts were added to the core layer solution to prepare a 15% (w / w) gradient doped solution. Citric acid chelating agent (8% of the total weight of the rare earth salts) was added to the doped solution, and the mixture was placed in a 60℃ constant temperature water bath. The stirring rate was 350 r / min, and the chelation reaction was carried out for 50 min. The pH was adjusted to 6.0 with dilute nitric acid to obtain the rare earth doped solution.

[0041] Composite Modification Mixture: Weigh 20 parts of kaolin modified with silane coupling agent KH550. The modification method is as follows: calcination of kaolin at 900℃ for 3 hours, cooling, and mixing with an 8% KH550 ethanol solution at a weight ratio of 10:1. Stirring reaction at 70℃ for 3 hours, filtering, drying at 85℃ for 5 hours, pulverizing, and passing through a 400-mesh sieve. The specific surface area is measured to be 50 m². 2 / g. Modified kaolin and the bifunctional modified matrix prepared in step 1 were added together into a conical mixer, and the speed was set to 1500 r / min for premixing for 25 min. Rare earth dopant solution was added dropwise at a rate of 2 mL / min using a peristaltic pump. After the addition was completed, mixing was continued for 40 min to obtain a mixed slurry with a solid content of 50%.

[0042] Surface modification and anti-aging modification: 2 parts of APG12-14 type alkyl polysaccharide surfactant and 8 parts of ternary anti-aging agent were added to the mixed slurry. The weight ratio of antioxidant 1010, antioxidant 168 and light stabilizer UV-327 in the ternary anti-aging agent was 4:1:1. The temperature of the mixing system was raised to 90℃, the stirring speed was 800r / min, and the reaction was carried out for 90min. During the reaction, the pH value was checked every 15min and maintained at about 7.2.

[0043] Drying and calcination molding: The modified slurry is fed into a spray dryer with an inlet temperature of 195℃ and an outlet temperature of 90℃. After drying, a precursor powder with a particle size of 20μm is obtained. The precursor powder is placed in a muffle furnace and heated to 500℃ at a rate of 8℃ / min under air atmosphere, and held at that temperature for 1 hour; then heated to 700℃ at a rate of 5℃ / min and calcined for 2.5 hours. After natural cooling, it is pulverized by an air jet mill at a pulverization pressure of 0.8MPa and passed through a 600-mesh standard sieve to obtain the anti-aging rare earth environmentally friendly pigment product.

[0044] (II) Application in coatings Pigment dispersion treatment: The prepared anti-aging rare earth environmentally friendly pigment is mixed with pure acrylic emulsion and epoxy resin E-44 in a weight ratio of 1:1 and the weight ratio of pigment to mixed base is 1:9. 2.5% of the pigment weight of polycarboxylate dispersant is added. The mixture is first pre-dispersed in a high-speed disperser at a speed of 3000 r / min for 25 min, and then transferred to a sand mill with a zircon bead filling rate of 75% and a grinding speed of 2200 r / min. The mixture is ground until the pigment particle size D90=75nm to obtain pigment paste.

[0045] Environmentally friendly coating preparation: Add 4% by weight of the coating base material of alcohol ester twelve film-forming aid and 0.5% of hydroxyethyl cellulose thickener to the pigment paste, stir and mix at 800 r / min for 20 min, adjust the coating viscosity to 75 KU and the pH value to 8.0 with deionized water to obtain rare earth environmentally friendly coating.

[0046] Coating and curing to form a film: The coating is applied to the surface of the phosphated cold-rolled steel sheet using air spraying. The phosphated film weighs 2.0 g / m². 2 The spraying pressure was 0.5 MPa, and the dry film thickness was 45 μm. The coating was pre-dried for 50 min at 25℃ and 60% relative humidity, then baked and cured in a 75℃ hot air oven for 2 h, and then naturally cooled to room temperature to obtain an anti-aging coating.

[0047] V. Comparative Example 1 (I) Preparation of conventional rare earth pigments Unmodified matrix treatment: Weigh 55 parts of wide-bandgap aluminosilicate matrix that has not been modified by hydroxyl-carboxyl bifunctional groups, with crystal form Al2O3·2SiO2·2H2O and particle size of 120nm, and directly crush it through a 350-mesh sieve for later use.

[0048] Preparation of rare earth mixed solution: Weigh 12 parts of rare earth salts, lanthanum nitrate, cerium nitrate, yttrium nitrate and erbium nitrate in a weight ratio of 2.5:1:3.5:1, dissolve in deionized water to prepare a mixed solution with a mass concentration of 13.5%. No citric acid chelating agent was added. The pH value was directly adjusted to 5.5 to obtain the rare earth mixed solution.

[0049] Mixed treatment: 15 parts of kaolin were weighed and calcined at 850℃ for 2.5 hours without silane coupling agent treatment. The specific surface area was measured to be 25 m². 2 / g, together with the unmodified matrix from step 1, is added to a conical mixer. The mixture is premixed at 1200 r / min for 22 min, and then the rare earth mixture is added dropwise at a rate of 1.5 mL / min. After the addition is complete, the mixture is mixed for 38 min to obtain the mixed slurry.

[0050] Surface modification and anti-aging treatment: Add 1.2 parts of sodium dodecylbenzenesulfonate surfactant and 5 parts of antioxidant 1010 single anti-aging agent to the mixed slurry, raise the temperature of the mixing system to 88℃, stir at 700r / min, react for 80min, and maintain the pH value at around 7.0.

[0051] Drying and calcination: The slurry is fed into a spray dryer with an inlet temperature of 190℃ and an outlet temperature of 88℃ to obtain precursor powder. The precursor powder is placed in a muffle furnace and heated directly to 680℃ at a heating rate of 10℃ / min, calcined for 2.2 hours, and then naturally cooled and pulverized through a 550-mesh sieve to obtain conventional rare earth pigments.

[0052] (II) Application in coatings Pigment dispersion treatment: Conventional rare earth pigments and pure acrylic emulsion are mixed at a weight ratio of 1:7.5, and 2.0% of polycarboxylate dispersant by weight of pigments is added. The mixture is pre-dispersed in a high-speed disperser at 2800 r / min for 23 min, and then ground in a sand mill with a zircon bead filling rate of 72% and a rotation speed of 2000 r / min until the particle size D90=150nm is obtained to obtain pigment paste.

[0053] Coating preparation: Add 3% by weight of the coating base material of the pigment paste, the film-forming aid of alcohol ester twelve and the thickener of 0.4% by weight of the pigment paste, stir and mix at 650 r / min for 18 min, adjust the viscosity to 65 KU and the pH value to 7.5 to obtain conventional rare earth coating.

[0054] Coating and curing: Using the same spraying parameters and curing conditions as in Example 1, a coating was prepared on the surface of a phosphated cold-rolled steel sheet.

[0055] VI. Performance Testing and Result Analysis (a) Testing methods Environmental performance: The content of heavy metals lead, cadmium, mercury and hexavalent chromium in pigments and coatings is tested according to GB / T 23991-2009 standard, and the content of volatile organic compounds (VOCs) is tested according to GB / T 23984-2009 standard.

[0056] Anti-aging performance: The coating was placed in an aging test chamber and subjected to a 1000-hour xenon lamp aging test. The color difference ΔE and gloss retention rate of the coating before and after aging were tested according to GB / T1865-2009 standard.

[0057] Dispersibility and storage stability: The pigment particle size D90 was measured using a laser particle size analyzer, and the zeta potential was measured using a zeta potential meter; the stratification and sedimentation of the coating after standing for 30 days were observed according to GB / T 6753.3-1986 standard.

[0058] Mechanical properties of the coating: The number of scrub resistance of the coating was tested according to GB / T 9266-2009 standard, and the coating adhesion was tested using the cross-cut test according to GB / T 9286-1998 standard.

[0059] Corrosion inhibition performance: The corrosion inhibition efficiency and corrosion inhibition period of the coating on cold-rolled steel sheets were tested using an electrochemical workstation.

[0060] The test results of the examples and comparative examples are compared in Table 1 below: Table 1

[0061] No banned heavy metals were detected in the products of Examples 1-3, and the VOC content was far lower than that of Comparative Example 1, meeting environmental protection standards. Due to the use of a bifunctional modified matrix, gradient rare earth doping, and ternary anti-aging additive compound system, the products of the examples have superior anti-aging performance, characterized by small color difference ΔE, high gloss retention, better dispersibility, small pigment particle size, and large absolute value of Zeta potential; good storage stability with no stratification or precipitation; and outstanding coating mechanical properties, with high resistance to scrubbing and strong adhesion.

[0062] Comparative Example 1, which did not employ the core modification technology and optimized process of this invention, exhibited severe rare earth ion aggregation and weak bonding with the matrix, resulting in poor pigment dispersion, inadequate anti-aging effects, and a significant decline in coating performance. This result fully demonstrates the advanced nature and superiority of the technical solution of this invention. The prepared anti-aging rare earth environmentally friendly pigment is superior to existing products in terms of environmental friendliness, anti-aging performance, structural stability, and application compatibility.

[0063] Reference Figure 2This invention demonstrates the significant advantages of the anti-aging rare earth environmentally friendly pigment in terms of environmental friendliness and dispersion stability. Traditional rare earth pigments use surfactants with high volatile organic compound (VOC) content, and the matrix is ​​not modified with bifunctional groups, while the kaolin is not treated with silane coupling agents. This results in high VOC release, weak binding force between rare earth ions and the matrix, easy agglomeration, and poor dispersion stability. This invention, by selecting environmentally friendly surfactants, modifying the aluminosilicate matrix with hydroxyl-carboxyl bifunctional groups, and modifying the kaolin with silane coupling agents, achieves comprehensive optimization from component selection to structural modification. This effectively reduces VOC release while enhancing the binding stability of rare earth ions and the matrix, thus improving pigment dispersion performance.

[0064] Reference Figure 3 This invention demonstrates the significant advantages of the anti-aging rare earth environmentally friendly pigment in terms of anti-aging performance and dispersibility. Traditional rare earth pigments are produced by mixing unmodified matrix with simple rare earth elements, without ionic hierarchical structure design and the addition of effective chelating agents. This results in the easy aggregation of rare earth ions and weak binding force with the matrix, leading to poor pigment dispersion and significant gloss loss in the coating after aging tests. This invention modifies the aluminosilicate matrix with hydroxyl-carboxyl bifunctional groups to provide stable coordination binding sites. A lanthanum-yttrium gradient doping design broadens the ultraviolet absorption band, and silane coupling agent-modified kaolin optimizes dispersion performance. Simultaneously, a scientific chelation and segmented heating calcination process reduces ion loss, resulting in more uniform and finer pigment particle sizes. The coating maintains high gloss even after long-term aging tests, with simultaneous improvements in anti-aging performance and dispersibility, fully meeting the application requirements of high-performance coatings.

[0065] Reference Figure 4 This invention demonstrates the comprehensive superiority of its anti-aging rare earth environmentally friendly pigments in terms of overall performance. Traditional rare earth pigments lack core technologies such as bifunctional matrix modification, gradient rare earth doping, and ternary anti-aging additive formulation. Furthermore, the kaolin is not modified with silane coupling agents, and the calcination process parameters are unreasonable. This results in shortcomings in various aspects, including environmental friendliness, anti-aging performance, dispersion stability, coating mechanical properties, and corrosion inhibition. For example, they contain banned heavy metals, have high volatile organic compound (VOC) content, and exhibit easy coating aging, poor scrub resistance, and inadequate corrosion inhibition. This invention, through multi-dimensional technological innovation, selects environmentally friendly components, specifically modifies the matrix and kaolin, designs a gradient doping structure and a compounded anti-aging additive, and optimizes the preparation and application processes. This results in a product free of banned heavy metals and with low VOC release, while significantly improving key properties such as anti-aging, dispersion stability, coating mechanical properties, and corrosion inhibition. All indicators are superior to traditional products, fully demonstrating the comprehensive advancement of the technical solution and meeting the diverse application needs of high-end coatings.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An anti-aging rare earth environmentally friendly pigment, characterized in that, It is prepared from the following components in parts by weight: 45-65 parts of wide-bandgap aluminosilicate matrix modified with hydroxyl-carboxyl bifunctional groups, 8-15 parts of rare earth composite ions doped with lanthanum and yttrium gradients, 10-20 parts of kaolin modified with silane coupling agent KH550, 0.5-2 parts of alkyl polysaccharide-type environmentally friendly surfactant, and 3-8 parts of ternary anti-aging additive; the wide-bandgap aluminosilicate matrix modified with hydroxyl-carboxyl bifunctional groups is an Al2O3·2SiO2·2H2O crystalline aluminosilicate modified by grafting maleic anhydride and ethylene glycol diglycidyl ether, with a hydroxyl grafting amount of 0.8-1.5 mmol / g, a carboxyl grafting amount of 0.5-1.0 mmol / g, and a particle size of 50-200 nm; in the rare earth composite ions doped with lanthanum and yttrium gradients, the lanthanide ions are predominantly La 3+ Ce 4+ As the core layer, yttrium ions are in the form of Y 3+ Er 3+ The outer layer is the core layer, and the weight ratio of the outer layer to the core layer is 1:1 to 1:1.

5. The ternary anti-aging additive is a compound of hindered phenolic antioxidants, phosphite auxiliary antioxidants and benzotriazole light stabilizers, with a weight ratio of 3:1:1 to 4:1:

1.

2. The anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, The lanthanide ions are a complex of lanthanum nitrate and cerium nitrate, with a weight ratio of 2:1 to 3:1; the yttrium ions are a complex of yttrium nitrate and erbium nitrate, with a weight ratio of 3:1 to 4:

1.

3. The anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, The kaolin modified with silane coupling agent KH550 is prepared as follows: kaolin is calcined at 800-900℃ for 2-3 hours, cooled, and then mixed with a 5%-8% KH550 ethanol solution at a weight ratio of 10:

1. The mixture is stirred and reacted at 60-70℃ for 2-3 hours. After filtration, drying, and pulverization, the kaolin is passed through a 300-400 mesh sieve. The specific surface area of ​​the modified kaolin is 35-50 m² / g. 2 / g.

4. The anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, The alkyl polysaccharide-type environmentally friendly surfactant is APG12-14 type alkyl polysaccharide, with a hydrophilic-lipophilic balance value of 12-14 and an adsorption capacity of 1.2-2.0 mg / g in the pigment system.

5. The anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, In the ternary anti-aging additive, the hindered phenolic antioxidant is antioxidant 1010, the phosphite auxiliary antioxidant is antioxidant 168, and the benzotriazole light stabilizer is light stabilizer UV-327.

6. The anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, The Al2O3·2SiO2·2H2O crystalline aluminosilicate has a hydroxyl grafting amount of 0.8-1.5 mmol / g, a carboxyl grafting amount of 0.5-1.0 mmol / g, and a particle size of 50-200 nm.

7. A preparation process for the anti-aging rare earth environmentally friendly pigment according to claim 1, characterized in that, Includes the following steps: S1. Preparation of bifunctional matrix: The wide-bandgap aluminosilicate matrix is ​​placed in a high-speed mixer, and a compound modifier of maleic anhydride and ethylene glycol diglycidyl ether is added. The amount of modifier added is 5%-8% of the weight of the aluminosilicate matrix. The mixture is stirred and reacted at 120-150℃ and 800-1200r / min for 1-2h. After cooling to room temperature, it is pulverized and passed through a 300-400 mesh sieve to obtain the aluminosilicate matrix modified with hydroxyl-carboxyl bifunctional groups. S2. Preparation of gradient rare earth doped solution: Weigh lanthanide salts and yttrium salts according to the weight ratio of the core layer to the outer layer. First, dissolve the lanthanide salts in deionized water to prepare a core layer solution with a mass concentration of 10%-12%. Then, dissolve the yttrium salts in the core layer solution to prepare a gradient doped solution with a mass concentration of 12%-15%. Add citric acid chelating agent, with the amount of chelating agent added being 6%-8% of the total weight of rare earth salts. Stir and chelate in a water bath at 55-60℃ for 45-50 minutes. Adjust the pH value to 5.0-6.0 to obtain the rare earth doped solution. S3. Composite Modification Mixing: Add the bifunctional modified matrix and silane coupling agent modified kaolin to a conical mixer and premix for 20-25 min at a speed of 1000-1500 r / min. Then, slowly add rare earth dopant solution at a rate of 1-2 mL / min. After the addition is complete, continue mixing for 35-40 min to obtain a mixed slurry with a solid content of 40%-50%. S4. Surface modification and anti-aging modification: Add alkyl polysaccharide surfactant and ternary anti-aging agent to the mixed slurry, stir and react at 85-90℃ and 600-800r / min for 70-90min, and check the pH value every 15min during the process to maintain the pH value at 6.8-7.

2. S5. Drying, calcining and molding: The modified slurry is placed in a spray dryer, and the inlet temperature is controlled at 185-195℃ and the outlet temperature at 85-90℃. The precursor powder with a particle size of 10-20μm is obtained. The precursor powder is placed in a muffle furnace and heated to 400-500℃ at a heating rate of 6-8℃ / min in air atmosphere and held for 1 hour. Then, it is heated to 650-700℃ at a heating rate of 3-5℃ / min and calcined for 2-2.5 hours. After naturally cooling to room temperature, it is pulverized by an air jet mill and passed through a 500-600 mesh sieve to obtain the anti-aging rare earth environmentally friendly pigment.

8. The preparation process of the anti-aging rare earth environmentally friendly pigment according to claim 7, characterized in that, In step S2, the lanthanide salts are lanthanum nitrate with a purity ≥99.9% and cerium nitrate with a purity ≥99.5%, which are used in a weight ratio of 2:1, and the coordination molar ratio of the lanthanide salts to the citric acid chelating agent is 1:1.4; the yttrium salts are yttrium nitrate with a purity ≥99.9% and erbium nitrate with a purity ≥99.5%, which are used in a weight ratio of 3:1, and the coordination molar ratio of the yttrium salts to the citric acid chelating agent is 1:1.3; the pulverizing pressure of the air jet mill in step S5 is 0.6-0.8 MPa.

9. A process for applying the anti-aging rare earth environmentally friendly pigment as described in claim 1 in coatings, characterized in that, Includes the following steps: S1. Pigment dispersion treatment: Mix anti-aging rare earth environmentally friendly pigments with coating base materials at a weight ratio of 1:6-1:9, add polycarboxylate dispersant, the amount of dispersant added is 1.5%-2.5% of the pigment weight, first pre-disperse in a high-speed disperser at a speed of 2500-3000r / min for 20-25min, then transfer to a sand mill, use zirconium beads as grinding media, the grinding media filling rate is 70%-75%, the grinding speed is 1800-2200r / min, grind until the pigment particle size D90≤100nm, to obtain pigment paste; S2. Preparation of environmentally friendly coatings: Add alcohol ester dodecyl film-forming aid and hydroxyethyl cellulose thickener to the pigment paste. The amount of film-forming aid added is 2%-4% of the weight of the coating base, and the amount of thickener added is 0.3%-0.5% of the weight of the coating base. Stir and mix at 500-800 r / min for 15-20 min. Adjust the viscosity of the coating to 55-75 KU and the pH value to 7.0-8.0 with deionized water to obtain rare earth environmentally friendly coatings. S3. Coating and Curing: The rare earth environmentally friendly coating is applied to the substrate surface by air spraying at a pressure of 0.3-0.5 MPa. The dry film thickness is 35-45 μm. It is pre-dried at 25℃ and 50%-60% relative humidity for 40-50 minutes, and then baked and cured in a hot air oven at 65-75℃ for 1.5-2 hours. After natural cooling to room temperature, an anti-aging coating is obtained.

10. The application process of the anti-aging rare earth environmentally friendly pigment in coatings according to claim 9, characterized in that, The coating base material mentioned in step S1 is at least one of pure acrylic emulsion and epoxy resin E-44; the substrate mentioned in step S3 is a cold-rolled steel sheet or polycarbonate sheet that has undergone phosphate treatment, and the film weight of the phosphate treatment is 1.5-2.0 g / m³. 2 .

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