Aging-resistant copper-gold powder pigment, and preparation method and application thereof

Abstract

The application discloses a kind of anti-aging copper gold powder pigments, its preparation method and application in the technical field of copper gold powder pigments.The anti-aging copper gold powder pigments take copper-zinc alloy as base material, sequentially have composite chemical passivation layer, functional organic-inorganic hybrid dense barrier layer and surface superhydrophobic layer by chemical bonding from inside to outside;The composite chemical passivation layer is formed by treating passivation solution containing phytic acid, ammonium metavanadate and sodium tungstate;The functional organic-inorganic hybrid dense barrier layer is constructed by silane mixed solution containing 3-mercaptopropyl triethoxysilane, reactive ultraviolet absorber Si-BP, reactive hindered amine light stabilizer Si-HALS and tetraethyl orthosilicate through sol-gel process.The application realizes the improvement of anti-aging performance of copper gold powder by multilayer composite system design, while the optical decoration performance can be retained to the maximum extent, and then the dual strict requirements of durability and visual texture for high-end outdoor applications such as automobile paint can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper gold powder pigments, and particularly relates to a kind of anti-aging copper gold powder pigments and its preparation method and application. BACKGROUND

[0002] The copper gold powder pigments have been widely used in many fields such as silk screen printing, printing packaging, paint, ink, coating, handicraft and toy manufacturing due to its unique metallic luster and gorgeous decorative effect. The core component of copper zinc alloy can provide a series of rich gold color tones from red gold, green gold to green gold, which meets the market's pursuit of luxurious appearance.

[0003] However, the traditional copper gold powder in the prior art has poor environmental aging resistance, especially insufficient ultraviolet aging resistance. This defect greatly limits the application of copper gold powder pigments in high-value and high-demand fields. In particular, in the automobile manufacturing industry, the metallic flash finish requires that the pigments not only have a brilliant metallic flash effect and goniochromism, but also must have long-term durability under extremely harsh conditions. In addition, the automobile paint surface is exposed to the outdoors all year round, and is subjected to strong ultraviolet radiation, severe temperature changes, rain, acid rain erosion and salt spray environment. The traditional copper gold powder cannot completely meet these requirements.

[0004] At present, the surface treatment is mostly adopted to solve the problem of poor aging resistance of copper gold powder, but there are many defects: first, the protective efficiency and durability are insufficient. For example, the conventional organic passivation film (such as benzotriazole BTA film) has poor ultraviolet resistance and is easily degraded by light under long-term sunlight, and its heat resistance cannot withstand the baking and curing temperature of automobile coatings above 140°C, resulting in rapid degradation of the protection function. In addition, a single inorganic passivation layer (such as silicate, phosphate) has micro defects and cannot effectively block the penetration of water vapor, oxygen and sulfides; second, the interface bonding force between the protective layer and the metal substrate is weak. The protective layer and the copper substrate are mainly combined by physical adsorption or weak intermolecular forces, which are easy to peel off between the layers under the conditions of wet heat, cold heat cycle or mechanical shear stress, resulting in protection failure; third, it is difficult to balance the long-term ultraviolet resistance and physical barrier performance. Ordinary ultraviolet absorbers and light stabilizers added by blending are easy to migrate and precipitate, which cannot provide long-term protection. While relying only on thickening the physical barrier layer will sacrifice the metallic luster and optical effect of the copper gold powder; fourth, it is difficult to balance environmental protection and high performance. High-efficiency but toxic chromium salt passivation process is limited by environmental regulations, and the comprehensive protection performance of the existing environmental protection alternative scheme often cannot meet the harsh requirements of automobile coatings.

[0005] The root cause is that the traditional process focuses on the adjustment of physical properties such as color and particle size, and does not fundamentally solve the core problems such as easy ozone oxidation and lattice structure damage of copper gold powder under the action of ultraviolet light. There is a lack of functional substances that can absorb / reflect ultraviolet light and self-repair mechanism. SUMMARY

[0006] The present application aims at the existing technical problems, and proposes a kind of anti-aging copper gold powder pigment and its preparation method and application, under the premise of environmental protection, through the innovative design of multilayer composite system, synchronous realization of extreme weather resistance, super strong interlayer adhesion, persistent active ultraviolet function and excellent metal optical effect, to meet the dual requirements of durability and appearance for automobile original factory paint.

[0007] The present application realizes the above-mentioned purposes by the following technical schemes:

[0008] As a first aspect of the present application, a kind of anti-aging copper gold powder pigment is provided, the anti-aging copper gold powder pigment is with copper-zinc alloy as substrate, sequentially connected with composite chemical passivation layer, functional organic-inorganic hybrid dense barrier layer and surface superhydrophobic layer by chemical bonding from inside to outside;Wherein,

[0009] The composite chemical passivation layer is formed by treating the passivation solution containing phytic acid, ammonium metavanadate and sodium tungstate;

[0010] The functional organic-inorganic hybrid dense barrier layer is constructed by silane mixed solution containing 3-mercaptopropyl triethoxysilane, reactive ultraviolet absorber Si-BP, reactive hindered amine light stabilizer Si-HALS and tetraethyl orthosilicate by sol-gel process;

[0011] The surface superhydrophobic layer is formed by grafting modification of fluorinated POSS hydrophobic agent.

[0012] As a further optimization scheme of the present application, in the passivation solution, phytic acid is 3-5 parts by weight, ammonium metavanadate is 0.8-1.2 parts by weight, and sodium tungstate is 1.2-1.8 parts by weight, and the solvent is 40-60 parts by weight of water.

[0013] As a further optimization scheme of the present application, in the silane mixed solution, 3-mercaptopropyl triethoxysilane is 2-4 parts by weight, reactive ultraviolet absorber Si-BP is 1.2-1.8 parts by weight, reactive hindered amine light stabilizer Si-HALS is 1.2-1.8 parts by weight, and tetraethyl orthosilicate is 7-9 parts by weight, and the solvent is 30-50 parts by weight of isopropanol.

[0014] As a further optimization scheme of the present application, the weight ratio of fluorinated POSS hydrophobic agent to copper-zinc alloy is 1-3:80-120.

[0015] As a second aspect of the present application, the application of the anti-aging copper gold powder pigment as described in any one of the above in the field of automobile paint is also provided.

[0016] As a third aspect of the present application, there is also provided a method for preparing the anti-aging copper-gold powder pigment as described in any one of the preceding aspects, comprising the following steps:

[0017] The pretreated copper-zinc alloy is dispersed in deionized water, heated in a water bath and stirred, the pH of the system is adjusted to 3.0-4.0, the passivation solution is slowly added to the reaction system, the temperature is kept constant, the pH of the system is adjusted to 6.5-7.5, and the reaction is continued to form a composite chemical passivation layer, and then the filter cake is filtered, washed and neutralized;

[0018] (2) The wet filter cake is dispersed in an isopropanol aqueous solution, a catalyst solution is added, heated in a water bath and stirred, the silane mixture is slowly added to the reaction system, and after heating, a functionalized organic-inorganic hybrid dense barrier layer is formed by reaction;

[0019] (3) The reaction system of step (2) is kept constant, a fluorinated POSS hydrophobic agent is added, heated, and an ultrahydrophobic surface modification layer is formed by reaction;

[0020] (4) The reaction system is cooled to room temperature, and then filtered, washed, vacuum dried and sieved to obtain the copper-gold powder pigment.

[0021] As a further optimization of the present application, in step (1), the pretreatment is to add 80-120 parts by weight of copper-zinc alloy to 400-600 parts by weight of organic solvent, ultrasonic dispersion for 20-40 min, filtration, washing with organic solvent for 1-3 times, drying in a vacuum oven at 70-90 ℃ for 3-5 h, and standby.

[0022] As a further optimization of the present application, in step (1), the weight ratio of deionized water to copper-zinc alloy is 300-500:80-120.

[0023] As a further optimization of the present application, in step (1), the water bath heating temperature is 50-70 ℃, the constant temperature reaction time is 20-40 min, and the continuous reaction time is 20-40 min.

[0024] As a further optimization of the present application, in step (2), the catalyst solution is a mixture of 25-30 % ammonia water and isopropanol in a volume ratio of 3-5:12-20.

[0025] As a further optimization of the present application, in step (2), the water bath heating temperature is 40-50 ℃, the temperature is raised to 45-55 ℃, and the reaction is carried out for 6-10 h.

[0026] As a further optimization of the present application, in step (3), the temperature is raised to 55-65 ℃, and the reaction is carried out for 2-4 h.

[0027] The present application has the beneficial effects of:

[0028] (1) The present application breaks through the limitations of traditional single layer / simple layer protection, and constructs a four-layer structure of "flaky copper-zinc alloy substrate-composite chemical passivation layer-functionalized organic-inorganic hybrid dense barrier layer-super-hydrophobic surface modification layer", and the functions of each layer are complementary to form a full-chain protection of "bottom layer corrosion resistance-middle layer UV resistance / scratch resistance-surface layer moisture resistance", which solves the problems of easy oxidation, poor weather resistance, and the incompatibility of optical performance and protective performance of copper and gold powder from the root;

[0029] (2) The present application innovatively permanently anchors the reactive ultraviolet absorber Si-BP and the reactive hindered amine light stabilizer Si-HALS in the organic-inorganic hybrid network through covalent bonds, which not only avoids the protective attenuation caused by the loss of traditional free additives during use, but also effectively captures the photoaging free radicals through Si-HALS and significantly absorbs the ultraviolet region through Si-BP, realizing the synergistic anti-ultraviolet effect of "ultraviolet absorption+chemical repair";

[0030] (3) The present application realizes the firm combination of the flaky copper-zinc alloy substrate and the composite chemical passivation layer through "phytic acid chelation+vanadium / tungstate co-deposition", anchors the composite chemical passivation layer and the functionalized organic-inorganic hybrid dense barrier layer by using the mercapto group (-SH) of MPTES to form Cu-S covalent bond, and relies on the Si-O-Si covalent bond to build the three-dimensional network inside the functionalized organic-inorganic hybrid dense barrier layer and the connection between the functionalized organic-inorganic hybrid dense barrier layer and the surface super-hydrophobic layer (fluorinated POSS), which completely solves the bottleneck of the traditional protection system relying on physical adsorption and easy interlayer peeling;

[0031] (4) The present application adopts a nanoscale ultrathin protective layer design, which realizes extreme anti-aging protection through multiple mechanisms while maximizing the retention of the mirror reflection characteristics and metal decorative texture of copper and gold powder, effectively resolves the technical problem that "anti-aging performance improvement" and "optical decorative performance retention" cannot be compatible, and finally realizes the synergy of "high anti-aging+high decorative", which fully meets the dual harsh requirements of durability and visual texture for high-end outdoor applications such as automotive coatings. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The SEM image of the copper and gold powder pigment obtained in Example 1 provided by the present application;

[0033] Figure 2 The TEM image of the copper and gold powder pigment obtained in Example 1 provided by the present application;

[0034] Figure 3The copper-gold powder pigment obtained from Example 1 of the present application and the coating sample prepared from the flaky copper-zinc alloy without any treatment are compared by spraying, high-temperature baking and plate preparation. DETAILED DESCRIPTION

[0035] It is necessary to point out here that the following detailed description is only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0036] The substrate is a flaky copper-zinc alloy powder pigment with a particle size of 15-25 μm, Cu: 70 %±1 %, Zn: 30 %±1 %;

[0037] The passivation solution is prepared by dissolving phytic acid 3-5 parts, ammonium metavanadate 0.8-1.2 parts, sodium tungstate 1.2-1.8 parts in 40-60 parts of warm water, and mixing;

[0038] The silane mixed solution is prepared by dissolving 3-mercapto propyl triethoxysilane MPTES 2-4 parts, reaction type ultraviolet absorber Si-BP 1.2-1.8 parts, reaction type hindered amine light stabilizer Si-HALS 1.2-1.8 parts, and tetraethyl orthosilicate TEOS 7-9 parts in 30-50 parts of isopropyl alcohol, and stirring uniformly to obtain;

[0039] The catalyst solution is prepared by mixing 3-5 mL of ammonia water (25-30 % mass concentration) and 12-20 mL of isopropyl alcohol.

[0040] The methods used in the present application are conventional methods known to those skilled in the art unless otherwise specified, and the reagents and other materials used are commercially available products unless otherwise specified.

[0041] Example 1

[0042] The anti-aging copper-gold powder pigment provided in the present embodiment is prepared by sequentially modifying a flaky copper-zinc alloy with a composite chemical passivation layer, a functionalized organic-inorganic hybrid dense barrier layer and a surface super-hydrophobic layer from inside to outside on the surface of the substrate, and the preparation method comprises the following steps:

[0043] (1) Pretreatment: 100 parts by weight of flaky copper-zinc alloy powder pigment is added into 500 parts by weight of isopropyl alcohol, ultrasonic dispersion for 30 min, filtration, washing with isopropyl alcohol for 2 times, drying in a vacuum oven at 80 ℃ for 4 h, and standby;

[0044] (2) Composite chemical passivation layer modification: First, weigh 4 parts by weight of phytic acid, 1 part by weight of ammonium metavanadate, and 1.5 parts by weight of sodium tungstate, and dissolve them in 50 parts by weight of 40°C warm water to prepare a passivation solution. Then, disperse the pretreated flaky copper-zinc alloy powder pigment in 400 parts by weight of deionized water, heat the water bath to 60°C, and mechanically stir at 250 rpm. Add a 5% volume fraction of dilute nitric acid solution to adjust the pH of the system to 3.5, then slowly add the passivation solution to the reaction system through a constant-pressure dropping funnel within 30 minutes, maintain a constant temperature of 60°C for 30 minutes, finally adjust the pH of the system to 7.0 with a 5% volume fraction of sodium hydroxide solution, and continue to react for 30 minutes. After the reaction is completed, filter and wash the filter cake with deionized water until it is neutral to obtain a passivation intermediate;

[0045] (3) Functional organic-inorganic hybrid dense barrier layer modification: Mix 3 ml of 25% ammonia water with 12 ml of isopropyl alcohol to prepare a catalyst solution. Weigh 3 parts by weight of MPTES, 1.5 parts by weight of Si-BP, 1.5 parts by weight of Si-HALS, and 8 parts by weight of TEOS, and dissolve them in 30 parts by weight of isopropyl alcohol to obtain a silane mixture. Disperse the passivation intermediate in 300 parts by weight of a mixed solvent of isopropyl alcohol / water (volume ratio 4:1), first add the catalyst to the reaction system, heat the water bath to 45°C, and stir, then slowly add the silane mixture to the reaction system at a constant speed within 90 minutes, and then heat to 50°C for constant temperature reaction for 8 hours to obtain a functional intermediate.

[0046] (4) Surface super-hydrophobic layer modification: Keep the reaction system of step (3), add 2 parts by weight of fluorinated POSS hydrophobic agent, heat to 60°C, and continue to react for 3 hours. After the reaction is completed, cool to room temperature, filter, wash the filter cake with anhydrous isopropyl alcohol for 3 times, dry the filter cake in a 80°C vacuum drying oven for 12 hours, and sieve through an 800 mesh sieve to obtain the anti-aging copper-gold powder pigment.

[0047] Example 2

[0048] The present embodiment provides a preparation method of an anti-aging copper-gold powder pigment, comprising the following steps:

[0049] (1) Pretreatment: Take 80 parts by weight of flaky copper-zinc alloy powder pigment, add 400 parts by weight of isopropyl alcohol, ultrasonic disperse for 20 minutes, filter, wash twice with isopropyl alcohol, and dry in a 70°C vacuum oven for 3 hours for standby;

[0050] (2) Composite chemical passivation layer modification: First, weigh 3 parts by weight of phytic acid, 0.8 parts by weight of ammonium metavanadate, and 1.2 parts by weight of sodium tungstate, and dissolve them in 40 parts by weight of 40°C warm water to prepare a passivation solution. Then, disperse the pretreated flaky copper-zinc alloy powder pigment in 300 parts by weight of deionized water, heat the water bath to 50°C, and mechanically stir at 250 rpm. Add a 5% volume fraction of dilute nitric acid solution to adjust the pH of the system to 3.0. Then, slowly add the passivation solution to the reaction system through a constant-pressure dropping funnel within 20 min, maintain a constant temperature of 50°C for 20 min, finally adjust the pH of the system to 6.5 with a 3% volume fraction of sodium hydroxide solution, and continue to react for 20 min. After the reaction is completed, filter and wash the filter cake with deionized water until it is neutral to obtain a passivation intermediate;

[0051] (3) Functionalized organic-inorganic hybrid dense barrier layer modification: Mix 3 ml of ammonia water (25% mass concentration) with 12 ml of isopropyl alcohol to prepare a catalyst solution. Weigh 2 parts by weight of MPTES, 1.2 parts by weight of Si-BP, 1.2 parts by weight of Si-HALS, and 7 parts by weight of TEOS, and dissolve them in 30 parts by weight of isopropyl alcohol to obtain a silane mixture. Disperse the passivation intermediate in 250 parts by weight of a mixed solvent of isopropyl alcohol / water (volume ratio of 3:1). First, add the catalyst to the reaction system, heat the water bath to 40°C, and stir. Then, slowly add the silane mixture to the reaction system at a constant speed within 60 min. After the addition is complete, increase the temperature to 45°C, and maintain the constant temperature for 6 h to obtain a functionalized intermediate.

[0052] (4) Surface super-hydrophobic modification: Maintain the reaction system of step (3), add 1 part by weight of fluorinated POSS hydrophobic agent, increase the temperature to 55°C, and continue to react for 2 h. After the reaction is completed, cool to room temperature, filter, wash the filter cake with anhydrous ethanol for 2 times, dry the filter cake in a 70°C vacuum drying oven for 10 h, and pass through an 800 mesh sieve to obtain an anti-aging copper-gold powder pigment.

[0053] Example 3

[0054] The present embodiment provides a method for preparing an anti-aging copper-gold powder pigment, which comprises the following steps:

[0055] (1) Pretreatment: Take 120 parts by weight of flaky copper-zinc alloy powder pigment, add 600 parts by weight of isopropyl alcohol, ultrasonically disperse for 40 min, filter, wash with isopropyl alcohol for 2 times, and dry in a 90°C vacuum oven for 5 h for standby use.

[0056] (2) Composite chemical passivation layer modification: First, take 5 parts by weight of phytic acid, 1.2 parts by weight of ammonium metavanadate, and 1.8 parts by weight of sodium tungstate, and dissolve them in 60 parts by weight of 40°C warm water to prepare a passivation solution. Then, disperse the pretreated flaky copper-zinc alloy powder pigment in 500 parts by weight of deionized water, heat the water bath to 70°C, and mechanically stir at 350 rpm. Add a 7% volume fraction of dilute nitric acid solution to adjust the system pH to 4.0, then slowly add the passivation solution to the reaction system through a constant-pressure dropping funnel within 40 minutes, maintain a constant temperature of 70°C for 40 minutes, finally adjust the system pH to 7.5 with a 7% volume fraction of sodium hydroxide solution, and continue to react for 40 minutes. After the reaction is completed, filter and wash the filter cake with deionized water until it is neutral to obtain the passivation intermediate;

[0057] (3) Functional organic-inorganic hybrid dense barrier layer modification: Mix 3 ml of ammonia water (25% mass concentration) with 12 ml of isopropyl alcohol to prepare a catalyst solution. Take 4 parts by weight of MPTES, 1.8 parts by weight of Si-BP, 1.8 parts by weight of Si-HALS, and 9 parts by weight of TEOS, and dissolve them in 50 parts by weight of isopropyl alcohol to obtain a silane mixture. Disperse the passivation intermediate in 350 parts by weight of a mixed solvent of isopropyl alcohol / water (volume ratio 5:1), first add the catalyst to the reaction system, heat the water bath to 50°C, and stir. Then, slowly add the silane mixture to the reaction system at a constant speed within 120 minutes, and after the addition is complete, increase the temperature to 55°C and maintain a constant temperature for 10 hours to obtain the functional intermediate.

[0058] (4) Surface super-hydrophobic layer modification: Maintain the reaction system of step (3), add 3 parts by weight of fluorinated POSS hydrophobic agent, increase the temperature to 65°C, and continue to react for 4 hours. After the reaction is completed, cool to room temperature, filter, wash the filter cake with anhydrous isopropyl alcohol twice, place the filter cake in a 90°C vacuum drying oven for 14 hours, and sieve through a 900 mesh sieve to obtain the anti-aging copper-gold powder pigment.

[0059] To explore the effects of composite chemical passivation layer modification, functional organic-inorganic hybrid dense barrier layer modification, and surface super-hydrophobic layer modification on the properties of copper-gold powder pigment, the following comparative examples are provided:

[0060] Comparative Example 1

[0061] The difference between Example 1 and Comparative Example 1 is that the anti-aging copper-gold powder pigment provided by Comparative Example 1 is not subjected to surface super-hydrophobic layer modification. That is, after obtaining the functional intermediate during the preparation of the copper-gold powder pigment, cool to room temperature, filter, wash the filter cake with anhydrous isopropyl alcohol twice, place the filter cake in a 80°C vacuum drying oven for 12 hours, and sieve through an 800 mesh sieve.

[0062] Comparative Example 2

[0063] In this comparative example, the composition of the passivation solution used in step (2) of Example 1 was adjusted. The passivation solution used in this comparative example was prepared by dissolving 4 parts by weight of phytic acid, 1 part by weight of ammonium molybdate, and 1.5 parts by weight of sodium tungstate in 50 parts by weight of warm water.

[0064] Comparative Example 3

[0065] In this comparative example, the composition of the silane mixture used in step (3) of Example 1 was adjusted. The silane mixture used in this comparative example was prepared by dissolving 3 parts by weight of MPTES and 8 parts by weight of TEOS in 30 parts by weight of isopropanol.

[0066] Comparative Example 4

[0067] In this comparative example, the composition of the silane mixture used in step (3) of Example 1 was adjusted. The silane mixture used in this comparative example was prepared by dissolving 3 parts by weight of MPTES, 8 parts by weight of TEOS, and 3 parts by weight of Si-BP in 30 parts by weight of isopropanol.

[0068] Comparative Example 5

[0069] In this comparative example, the composition of the silane mixture used in step (3) of Example 1 was adjusted. The silane mixture used in this comparative example was prepared by dissolving 3 parts by weight of MPTES, 8 parts by weight of TEOS, and 3 parts by weight of Si-HALS in 30 parts by weight of isopropanol.

[0070] Comparative Example 6

[0071] The difference between this comparative example and Example 1 is that the anti-aging copper-gold powder pigment provided in this comparative example was not modified with a functionalized organic-inorganic hybrid dense barrier layer. That is, step (3) was not performed, and after step (2) was completed, the filter cake was redissolved in anhydrous isopropanol and stirred. Then, 2 parts by weight of a fluorinated POSS hydrophobic agent was added, the temperature was raised to 60°C, and the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled to room temperature, and the filter cake was washed with anhydrous isopropanol three times. The filter cake was then dried in a vacuum drying oven at 80°C for 12 hours and sieved through an 800-mesh screen.

[0072] Comparative Example 7

[0073] The difference between Example 1 is that the anti-aging copper-gold powder pigment provided by the present comparative example is not modified by functional organic-inorganic hybrid dense barrier layer and surface super-hydrophobic layer, that is, after obtaining the passivation intermediate, the copper-gold powder pigment is directly placed in a 80 ℃ vacuum drying oven for drying for 12 h, and is passed through an 800 mesh sieve.

[0074] Comparative Example 8

[0075] In the present comparative example, the passivation solution in Example 1 step (2) is adjusted, and the passivation solution used in the present comparative example is 2 parts by weight of BTA dissolved in 30 parts by weight of anhydrous isopropanol to obtain a mixture.

[0076] The pretreated flaky copper-gold powder alloy is dispersed in 400 parts by weight of anhydrous isopropanol, heated in a water bath to 60 ℃, mechanically stirred at 250 rpm, and the passivation solution is slowly added to the reaction system within 30 min using a constant pressure dropping funnel, and the reaction is maintained at 60 ℃ for 60 min. After the reaction is completed, the passivation intermediate is obtained by filtration and washing the filter cake twice with anhydrous isopropanol; the remaining steps are the same as in Example 1 to obtain the copper-gold powder pigment.

[0077] The copper-gold powder pigments obtained in Examples 1-3 and Comparative Examples 1-8 are subjected to the following performance tests:

[0078] SEM, TEM tests

[0079] The copper-gold powder pigment obtained in Example 1 is selected for SEM, TEM tests. The test results are shown in Figures 1-2 The copper-gold powder pigment has a uniform and dense coating structure, achieving complete surface protection.

[0080] (2) Gloss performance test

[0081] The copper-gold powder pigments prepared in Examples 1-3 and Comparative Examples 1-8 are taken, and are mixed uniformly according to copper-gold powder pigment: dispersion (glycol butyl ether): varnish (water-based polyurethane resin) = 1:1.5:7.5 (mass ratio) to obtain paint, and the paint is used to prepare a 50 μm paint film on a sample plate using a four-sided applicator, and the sample plate is obtained after drying at room temperature. After calibration, 5 points on each plate are tested using a BYK 60° gloss meter, and the average value is taken. In addition, a flaky copper-zinc alloy without any treatment (blank control) is also prepared into paint and sample plate, and subjected to gloss performance test.

[0082] The test results are shown in Table 1.

[0083] Table 1, gloss performance test results

[0084] ;

[0085] As can be seen from Table 1, the luster performance of Examples 1-3 is significantly better than that of Comparative Examples, the 60° gloss can reach more than 85%, and the copper gold powder pigments of Examples 1-3 are constructed with a four-layer structure of "flaky copper-zinc alloy substrate-composite chemical passivation layer-functionalized organic-inorganic hybrid dense barrier layer-super-hydrophobic surface modification layer". The amount of fluorinated POSS hydrophobic agent used in the outermost layer of Example 2 is less and the modification reaction conditions are relatively mild, which leads to insufficient grafting density and regularity of POSS molecules on the particle surface, resulting in insufficient super-hydrophobic properties. When applied to a water-based paint system, this defective hydrophobic layer cannot provide sufficient and uniform repulsive force for the copper gold powder, thereby affecting the directional arrangement and floating property of the pigment during the film-forming process, ultimately leading to a decrease in the surface flatness of the paint film and a decrease in the metallic luster. However, the gloss is still significantly better than that of the comparative examples.

[0086] (2) Salt fog resistance test

[0087] The copper gold powder pigments obtained in Examples 1-3 and Comparative Examples 1-8 were mixed uniformly according to copper gold powder: dispersion (ethylene glycol butyl ether): varnish (water-based acrylic resin) = 1:1.5:7.5 (mass ratio), and finally deionized water was added (mass ratio of copper gold powder to deionized water was 1:3) to adjust the viscosity, to obtain the corresponding paint samples. The paint samples were prepared on a cleaned tinplate panel (substrate) (70x150x1 mm) by first spraying an epoxy primer (about 20 μm) at room temperature for 24 h, then spraying a copper gold powder coating (about 30 μm) at 150 ℃ for 30 min. The coating was tested according to the combined test scheme and rating process of "GB / T 10125-1997 Salt Spray Test" and "GB / T 30789-2015 Paints and Varnishes Evaluation of Corrosion Resistance of Coatings", and in addition, a flaky copper-zinc alloy without any treatment was used as a blank control, and the paint samples were prepared and sprayed on the panel according to the same operation as above:

[0088] Experimental conditions: The experiment was carried out in a BGD881 salt spray corrosion test chamber, the salt spray type was continuous spraying, the duration was 240 h, the test temperature was controlled at 35±1 ℃, the pressure barrel and the salt water barrel were maintained at 36 ℃ and 35 ℃ respectively, the salt water used for spraying was a 5.0±0.1 % NaCl solution (analytical pure), the pH was 6.5-7.2, the conductivity of distilled water was 1.76 mS / m, the salt spray deposition was 1.0-2.0 mL / 80 cm 2 h, the air pressure in the chamber was maintained at 1.0 kPa, the relative humidity of the machine environment was ≤85%, and the test sample was placed in the chamber at an inclination angle of 15°.

[0089] The detection indexes are as follows:

[0090] ① Adhesion loss rate (peeling area %): salt spray after the grid method, reference standard GB / T 9286; the calculation formula is as follows:

[0091] ;

[0092] ② Color difference ΔE, 5 points before and after salt spray to measure L, a, b value; the calculation formula is as follows:

[0093] ;

[0094] ③ Bubble density: microscopic observation of 1 cm 2 Area bubble number, units of cm 2 , the calculation formula is as follows:

[0095] ;

[0096] ④ Cracking grade: the evaluation standard of cracking grade is shown in Table 2, digital microscope observation under 200x scanning 1 cm 2 Area, the number of cracks and width are counted, and the cracking area ratio calculation formula is as follows:

[0097] ;

[0098] ⑤ Corrosion grade (Ri): the rating standard of corrosion grade is shown in Table 3.

[0099] Table 2, cracking grade evaluation standard

[0100] ;

[0101] Table 3, corrosion grade (Ri) rating standard

[0102] ;

[0103] The results of salt spray resistance performance test of copper gold powder pigments obtained in Examples 1-3 and Comparative Examples 1-8 and untreated flaky copper zinc alloy (blank control) are shown in Table 4.

[0104] Table 4, salt spray resistance performance test results

[0105] ;

[0106] As can be seen from Table 4, the salt spray resistance of the copper-gold powder pigments of Examples 1-3 is significantly better than that of the Comparative Examples. Comparative Example 1 is not modified by a super-hydrophobic layer, resulting in insufficient super-hydrophobic properties. When applied to a water-based paint system, the defective hydrophobic layer cannot provide sufficient and uniform repulsion to the copper-gold powder, resulting in significantly lower salt spray resistance than the Examples. The core reason for the lower salt spray resistance of Comparative Examples 2-8 than the Examples is that the construction of the "functionalized organic-inorganic hybrid dense barrier layer" is defective. The barrier layer that is not dense enough cannot effectively block the penetration of chloride ions, water vapor and oxygen, and the corrosion medium easily reaches the bottom layer and causes the coating to blister, peel and the substrate to corrode.

[0107] (3) Aging resistance test

[0108] The copper-gold powder pigments obtained in Examples 1-3 and Comparative Examples 1-8 were mixed uniformly by high shear at a mass ratio of copper-gold powder pigment: black plastic powder = 1:19 to obtain paint samples. Each paint sample was sprayed on an aluminum alloy plate by electrostatic spraying (70 kV) and cured by baking at 230 °C for 10 min to prepare a plate.

[0109] In addition, a flaky copper-zinc alloy without any treatment was used as a blank control, and paint samples were prepared according to the same procedure described above.

[0110] Figure 3 Comparing the sample plates prepared from the copper-gold powder pigment obtained in Example 1 and the flaky copper-zinc alloy without any treatment, it can be seen that the flaky copper-zinc alloy without any treatment is not resistant to high temperature and becomes black after electrostatic spraying and baking at 230 °C, and the metallic luster of the copper-gold powder decreases.

[0111] The aging resistance test method was performed according to the GSB-AL-631-2017 standard. The sample size was 100x150 mm aluminum alloy plate (coating thickness 60±5 μm). The test was performed in a Q-SUN Xe-3-HS xenon lamp aging oven. The lamp type was UVB-313 (ultraviolet wavelength peak 310 nm). The cycle program was as follows: (A) UV stage: 4 h irradiation, blackboard temperature (50±3) °C, irradiance (0.75±0.02) W / m 2 @310 nm; (B) condensation stage: 4 h condensation, oven temperature (40±3) °C, relative humidity >95%; (C) alternating cycle: 1 cycle (UV 4 h→condensation 4 h) every 8 h, total test time 1000 h (125 cycles).

[0112] The detection indicators are as follows:

[0113] ① Color difference ΔE, 5 points were measured before / after aging to obtain L, a, b values, L1, a1, b1; the calculation formula is as follows:

[0114] ;

[0115] In the formula: L1, a1, b1 are pre-aging data; L2, a2, b2 are post-aging data;

[0116] ② Light loss rate: 5 points were measured before / after aging to obtain 60° gloss, and the calculation formula is as follows:

[0117] ;

[0118] In the formula: G0 is the pre-aging 60° gloss data; G t is the post-aging 60° gloss data;

[0119] ③ Powdering grade: transparent pressure-sensitive adhesive tape (adhesion 10±1 N / 25 mm) was pressed on the coating surface, and after vertical peeling, the powder particles adhered to the tape were observed. The gray scale difference (ΔW) before and after the tape was measured by a whiteness meter, and the powdering degree was calculated. The evaluation criteria for the powdering grade are shown in Table 5;

[0120] ④ Evaluation criteria for cracking grade: the evaluation criteria for cracking grade are shown in Table 2. The number and width of cracks were counted under 200x scanning of a 1 cm 2 area by a digital microscope, and the cracking area ratio calculation formula is as follows:

[0121] .

[0122] Table 5, evaluation criteria for powdering grade

[0123] ;

[0124] The results of the aging resistance performance test of the copper-gold powder pigment samples of Examples 1-3, Comparative Examples 1-8 and the blank control group are shown in Table 6.

[0125] Table 6, results of the aging resistance performance test

[0126] ;

[0127] As can be seen from the table, the aging resistance performance of the copper-gold powder pigments of Examples 1-3 is better than that of the comparative examples. Analysis of the preparation methods of the comparative examples and the examples shows that the defects in the construction of the “functionalized organic-inorganic hybrid dense barrier layer” also play a dominant role in the light aging resistance performance; in addition, the deficiency of the hydrophobic layer also makes water more easily adhere and participate in the light aging process, which together accelerates the photooxidative degradation of the pigment and the powdering of the coating.

[0128] Based on the results of the above performance tests, the following conclusions are drawn:

[0129] The copper gold powder pigment of the present application is composed of the following four layers from inside to outside: flaky copper-zinc alloy (substrate), composite chemical passivation layer, functionalized organic-inorganic hybrid dense barrier layer, and surface super-hydrophobic layer.

[0130] Firstly, the composite chemical passivation layer is formed by treating the passivation solution prepared from phytic acid, ammonium metavanadate and sodium tungstate, and the firm combination of the substrate and the composite chemical passivation layer is achieved through "phytic acid chelation + vanadium / tungstate co-deposition";

[0131] Secondly, the functionalized organic-inorganic hybrid dense barrier layer is constructed by the silane mixed solution prepared from MPTES, Si-BP, Si-HALS and TEOS through sol-gel process, and the reactive ultraviolet absorber Si-BP and the reactive hindered amine light stabilizer Si-HALS are permanently anchored in the organic-inorganic hybrid network through covalent bond, which not only completely avoids the attenuation of protection function caused by the loss of additives, but also effectively blocks the ultraviolet light from deteriorating the copper substrate and the coating layer through the specific strengthening of Si-BP on the ultraviolet region absorption which is significantly damaged by the photo-oxidation of copper gold powder, and the high-efficiency capture of various free radicals generated in the photo-aging process by Si-HALS, forming a full-chain protection of "ultraviolet spectrum absorption + chemical damage repair". In addition, the strong Cu-S covalent bond is formed between the mercapto-containing silane coupling agent MPTES and the surface of the flaky copper-zinc alloy (substrate), realizing the molecular-level anchoring of the protection system and the substrate, and combining the three-dimensional dense network constructed by the Si-O-Si covalent bond inside the functionalized organic-inorganic hybrid dense barrier layer, which greatly improves the structural stability and long-term integrity of the protection system, and is conducive to solving the bottleneck of the existing protection system and copper substrate which relies on physical adsorption or weak hydrogen bond combination, and easily peels off between layers under long-term outdoor aging, leading to protection failure.

[0132] Finally, the surface super-hydrophobic layer is formed by grafting modification with fluorinated POSS hydrophobic agent, and the functions of each layer are complementary to form a full-chain protection of "bottom layer corrosion resistance - middle layer ultraviolet resistance / scratch resistance - surface layer moisture resistance", which solves the problem of easy oxidation, poor weather resistance, and the incompatibility of optical performance and protection performance of copper gold powder from the root.

[0133] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. An age-resistant copper gold powder pigment, characterized in that, The anti-aging copper gold powder pigment takes copper-zinc alloy as a substrate, and sequentially has a composite chemical passivation layer, a functionalized organic-inorganic hybrid dense barrier layer and a surface super-hydrophobic layer connected by chemical bonding from inside to outside, wherein The composite chemical passivation layer is formed by treating the passivation solution containing phytic acid, ammonium metavanadate and sodium tungstate; The functionalized organic-inorganic hybrid dense barrier layer is constructed by sol-gel process of the silane mixed solution containing 3-mercaptopropyl triethoxysilane, reactive ultraviolet absorber Si-BP, reactive hindered amine light stabilizer Si-HALS and tetraethyl orthosilicate; The surface super-hydrophobic layer is formed by grafting modification of the fluorinated POSS hydrophobic agent.

2. The weather resistant copper gold powder pigment according to claim 1, characterized in that, In the passivation solution, the phytic acid is 3-5 parts by weight, the ammonium metavanadate is 0.8-1.2 parts by weight, the sodium tungstate is 1.2-1.8 parts by weight, and the solvent is 40-60 parts by weight of water.

3. The weatherable copper gold pigment according to claim 1, wherein, In the silane mixed solution, the 3-mercaptopropyl triethoxysilane is 2-4 parts by weight, the reactive ultraviolet absorber Si-BP is 1.2-1.8 parts by weight, the reactive hindered amine light stabilizer Si-HALS is 1.2-1.8 parts by weight, the tetraethyl orthosilicate is 7-9 parts by weight, and the solvent is 30-50 parts by weight of isopropanol.

4. The weatherable copper gold pigment according to claim 1, wherein, The weight ratio of the fluorinated POSS hydrophobic agent to the copper-zinc alloy is 1-3:80-120.

5. The anti-aging copper gold powder pigment according to any one of claims 1-4 is applied in the field of automobile coatings.

6. The method of claim 1-4, wherein the method is characterized by, The method comprises the following steps: (1) dispersing the pretreated copper-zinc alloy in deionized water, heating and stirring in a water bath, adjusting the pH of the system to 3.0-4.0, slowly adding the passivation solution to the reaction system, adjusting the pH of the system to 6.5-7.5, continuing to react to form a composite chemical passivation layer, and then filtering, washing the filter cake to neutral; (2) dispersing the wet filter cake in an isopropanol aqueous solution, adding a catalyst solution, heating and stirring in a water bath, slowly adding the silane mixed solution to the reaction system, and then reacting to form a functionalized organic-inorganic hybrid dense barrier layer after heating; (3) maintaining the reaction system of step (2), adding a fluorinated POSS hydrophobic agent, and then reacting to form a super-hydrophobic surface modification layer after heating; (4) cooling the reaction system to room temperature, then filtering, washing the filter cake, vacuum drying and sieving to obtain a copper gold powder pigment.

7. The method of claim 6, wherein the method further comprises the step of adding a dispersant to the mixture of copper and gold particles. In step (1), the weight ratio of the deionized water to the copper-zinc alloy is 300-500:80-120.

8. The method of claim 6, wherein the method is characterized by, In step (2), the catalyst solution is a mixture of 25-30 % ammonia water and isopropanol in a volume ratio of 3-5:12-20.

9. The method for preparing an aging-resistant copper-gold powder pigment according to claim 6, characterized in that, In step (2), the water bath heating temperature is 40-50 ℃, the temperature is raised to 45-55 ℃, and the reaction is carried out for 6-10 h.

10. The method of claim 6, wherein the method is characterized by: In step (3), the temperature is raised to 55-65 ℃, and the reaction is carried out for 2-4 h.

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