High-stability copper-gold powder pigment, preparation method and application thereof

Abstract

The application relates to a high-stability copper-gold powder pigment and a preparation method and application thereof, and the preparation method comprises the following steps: ball milling copper-zinc alloy coarse powder, stearic acid and a compounded passivator after dissolution under a nitrogen atmosphere, screening, washing and suction filtering the ball milling product to obtain an amino-functionalized passivation base material; dispersing the amino-functionalized passivation base material in anhydrous isopropyl alcohol to obtain a reaction system, adding deionized water and a catalyst, dissolving tetraethyl orthosilicate and phenyl triethoxysilane in anhydrous isopropyl alcohol, slowly adding and heat-treating, suction filtering, washing and obtaining a phenyl-modified SiO2 coated intermediate; dispersing the phenyl-modified SiO2 coated intermediate in anhydrous isopropyl alcohol to obtain a mixed system, heating and stirring, dissolving a compounded stabilizer in anhydrous isopropyl alcohol, adding the compounded stabilizer into the mixed system for reaction, centrifuging, washing, vacuum drying and obtaining the copper-gold powder pigment. The copper-gold powder pigment has excellent oxidation resistance, chemical corrosion resistance and long-term storage stability, and can maximize the metallic original color luster.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper gold powder pigments, and particularly relates to a copper gold powder pigment with high stability and a preparation method and application thereof. BACKGROUND

[0002] As an important metal effect pigment, copper gold powder is widely used in the packaging and printing of high-end tobacco and alcohol, cosmetics, gifts and other products due to its dazzling metallic luster and magnificent decorative effect, and is one of the key materials for improving the appearance grade and brand value of products.

[0003] However, the application of traditional copper gold powder in the field of tobacco and alcohol packaging faces significant inherent defects and challenges. First, the visual effect of tobacco and alcohol packaging requires high durability, but the copper component in copper gold powder is chemically active and is easily eroded by oxygen, moisture and sulfides (such as hydrogen sulfide) in the environment, leading to oxidation and sulfidation reactions on its surface, generating black copper oxide (CuO) or dark copper sulfide (CuS), thus causing the pigment to lose its original luster, color to become dark and black, i.e., the so-called "oxidation blackening" phenomenon. Second, ordinary copper gold powder is poor in chemical corrosion resistance and easily reacts and discolors due to the contact with alcohol, grease, sweat and a small amount of chemicals in the packaging adhesive during the production, storage and circulation of tobacco and alcohol packaging. Third, to ensure print adaptability, the connecting agent in the ink may be slightly acidic or alkaline, which can also accelerate the corrosion of copper gold powder. These chemical instabilities directly lead to two serious consequences:

[0004] First, the printed products gradually deteriorate over time during the storage and shelf period, affecting the appearance of the products and the brand image.

[0005] Second, the pigment itself is prone to caking, agglomeration and pre-oxidation during storage, which reduces its dispersibility and printing performance, shortens the shelf life and adversely affects the stability of the production process and cost control.

[0006] To improve its stability, existing technologies often use benzotriazole and other organic corrosion inhibitors for passivation treatment, or coat a layer of silica, alumina and other inorganic protective layers on the surface. However, a single benzotriazole treatment layer has limited protective effect in high temperature and high humidity environments and may migrate and fail; and traditional inorganic coating layers are often thick or lack sufficient density, which improves the oxidation resistance to some extent but is difficult to balance the negative impact on metallic luster (leading to a decrease in gloss) and the bonding problem during mechanical rolling, and the overall protection capability in complex environments is still insufficient.

[0007] Therefore, it has become an urgent technical problem to develop a high-stability copper-gold powder pigment that can simultaneously have excellent oxidation resistance, chemical corrosion resistance, long-term storage stability, and can maximize the retention of the original luster of the metal, to meet the stringent requirements of high-end cigarette and liquor packaging. SUMMARY

[0008] The present application aims to solve the technical problems of existing copper-gold powder pigments for high-end cigarette and liquor packaging, such as easy oxidation discoloration, poor chemical corrosion resistance, and insufficient storage stability, and provides a high-stability copper-gold powder pigment, a preparation method and application thereof.

[0009] The present application achieves the above-mentioned purposes through the following technical solutions:

[0010] A preparation method of a high-stability copper-gold powder pigment, comprising the following steps:

[0011] S1, put copper-zinc alloy coarse powder, zirconium oxide grinding ball, and stearic acid into a ball mill; dissolve the compounded passivation agent with anhydrous isopropyl alcohol, stir uniformly, and then add to the ball mill; obtain a ball-milled product under a nitrogen atmosphere; and obtain an amino-functionalized passivation substrate after screening, washing, and suction filtration of the ball-milled product;

[0012] S2, disperse the amino-functionalized passivation substrate obtained in step S1 in anhydrous isopropyl alcohol to obtain a reaction system, add deionized water and a catalyst (triethanolamine) to heat, dissolve tetraethyl orthosilicate and phenyltriethoxysilane in anhydrous isopropyl alcohol, slowly add to the reaction system for heat preservation reaction, and then obtain a phenyl-modified SiO2 coated intermediate after suction filtration and washing;

[0013] S3, disperse the phenyl-modified SiO2 coated intermediate obtained in step S2 in anhydrous isopropyl alcohol to obtain a mixed system, heat and stir, dissolve the compounded stabilizer in anhydrous isopropyl alcohol, add to the mixed system after pre-reaction for a certain period of time, and obtain a copper-gold powder pigment after centrifugation, washing, and vacuum drying.

[0014] As a further optimization scheme of the present application, in step S1, the mass ratio of the copper-zinc alloy coarse powder, stearic acid, and compounded passivation agent is 100:2-3:2-4;

[0015] The mass ratio of the compounded passivation agent to anhydrous isopropyl alcohol is 0.5-2:100;

[0016] The compounded passivation agent comprises 2-amino benzothiazole and diethanolamine molybdate in a mass ratio of 0.5-2:1.

[0017] As a further optimization scheme of the present application, the ball mill is a variable-speed temperature-controlled ball mill, which is a three-stage variable-speed temperature-controlled ball mill, wherein stage one is 85-95 rpm, 40-60 DEG C, 3-5 h; stage two is 65-80 rpm, 40-50 DEG C, 8-13 h; and stage three is 50-60 rpm, 35-45 DEG C, 2-4 h.

[0018] As a further optimization scheme of the present application, in step S2, the amino-functionalized passivation substrate, deionized water, catalyst, tetraethyl orthosilicate and phenyltriethoxysilane are included in an amount of 45-55 parts by weight, 10-15 parts by weight, 3-8 parts by weight, 8-15 parts by weight and 0.5-2 parts by weight, respectively.

[0019] As a further optimization scheme of the present application, the mass ratio of the amino-functionalized passivation substrate to anhydrous isopropanol is 1:5-7; and the mass ratio of the total mass of the tetraethyl orthosilicate and phenyltriethoxysilane to anhydrous isopropanol is 1:3-4.5.

[0020] As a further optimization scheme of the present application, in step S2, the reaction temperature is 65-80 DEG C, and the reaction time is 2-10 h.

[0021] As a further optimization scheme of the present application, the mass ratio of the phenyl-modified SiO2-coated intermediate to anhydrous isopropanol is 1:2-4.

[0022] The mass ratio of the phenyl-modified SiO2-coated intermediate to the compound stabilizer is 50:2-5.

[0023] The compound stabilizer includes 3-(glycidyloxy)propyltrimethoxysilane and aminopropyl-terminated polydimethylsiloxane in a mass ratio of 0.5-1.5:1.

[0024] As a further optimization scheme of the present application, in step S3, the reaction temperature is 55-70 DEG C, and the reaction time is 2-5 h.

[0025] A high-stability copper-gold powder pigment prepared by the above preparation method.

[0026] The application of a high-stability copper-gold powder pigment in the preparation of a high-performance color paint, wherein the high-performance color paint has high metal gloss, chemical corrosion resistance and high storage stability.

[0027] The present application has the following advantages:

[0028] 1) The invention forms an organic chelation and inorganic oxidation composite film on the inner layer to enhance the intrinsic corrosion resistance of the substrate; the intermediate layer of phenyl-modified silica introduces molecular-level flexibility while maintaining the dense barrier properties, improving the brittle fracture tendency of traditional pure silica layer; the outer layer of epoxy-amino siloxane crosslinking network provides dynamic protection, significantly delays the color fading under harsh environment, and makes the product maintain optical and chemical stability for a long time under conditions such as humidity and salt spray;

[0029] 2) The copper-gold powder pigment provided by the invention has the following application performance: through the Si-N bond,

[0030] Si-O-C ether bond and hydrogen bond network, the molecular suture is realized, the interlayer bonding force and wear resistance are greatly improved; the steric hindrance effect effectively inhibits storage agglomeration, the powder flowability and dispersibility are obviously optimized, and the powder can be directly applied to high-end printing scenes; in the field of sustainability, the full-process single anhydrous isopropanol solvent design simplifies the recycling process and reduces environmental load; the heavy metal-free formula considers safety and regulatory compliance, and gives the product a broader application prospect; this multi-dimensional innovation provides a copper-gold powder solution for the high-end packaging field, which has long-term protection, visual performance and ecological friendly features;

[0031] 3) In the invention, the complexing passivator and its synergistic effect: 2-amino benzothiazole and diethanolamine molybdate are compounded, which produces a synergistic effect of "chemical adsorption + oxidation film formation", and its effect is much better than other complexing passivators or single passivators, indicating that there is a synergistic effect between them.

[0032] 4) In the invention, the complexing stabilizer and its synergistic effect: 3- (glycidyl ether oxy) propyl trimethoxysilane and amino-terminated polydimethylsiloxane are compounded, a stable outer layer connected by covalent bonds is formed through chemical reaction, providing extreme spatial stability based on the principle of entropy repulsion, and its effect is much better than other complexing stabilizers or single stabilizers, indicating that there is a synergistic effect between them;

[0033] 5) In the invention, the variable-speed temperature control ball milling process: a three-stage variable-speed ball milling strategy (high-speed impact, medium-speed grinding, low-speed polishing / passivation) is adopted, and accurate rotation speed, time and temperature parameters are matched, to ensure that high flakiness, low surface defect substrate is obtained, and uniform passivation layer is realized. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a scanning electron microscope (SEM) image of the copper-gold powder of embodiment 4 of the invention.

[0035] Figure 2 is a transmission electron microscope (TEM) image of the copper-gold powder of embodiment 4 of the invention. DETAILED DESCRIPTION

[0036] The application will be further described in detail below with reference to the drawings. It is necessary to point out that the following specific embodiments are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Those skilled in the art can make some non-essential improvements and adjustments to the application according to the above application content.

[0037] 1. Copper-zinc alloy coarse powder: Cu: 70%±1%, Zn: 30%±1%.

[0038] 2. Zirconium oxide grinding ball: the amount of the zirconium oxide grinding ball is 5-7 kg per 1 kg of copper-zinc alloy coarse powder, and the particle size of the zirconium oxide grinding ball is 2-15 mm. The zirconium oxide grinding ball used in the application is a mixture of zirconium oxide grinding balls with a particle size of 5 mm and zirconium oxide grinding balls with a particle size of 10 mm in a mass ratio of 1:1;

[0039] 3. Compound passivator: 2-amino benzothiazole and diethanolamine molybdate in a mass ratio of 0.5-2:1;

[0040] 4. Compound stabilizer: 3-(glycidyloxy)propyltrimethoxysilane and aminopropyl-terminated polydimethylsiloxane in a mass ratio of 0.5-1.5:1;

[0041] 5. Catalyst: triethanolamine;

[0042] 6. Phenyl-modified silicon dioxide raw material: tetraethyl orthosilicate, phenyl triethoxysilane (containing a phenyl hydrophobic group);

[0043] The methods used in the application are conventional methods known to those skilled in the art unless otherwise specified. The reagents and other materials used are commercially available products unless otherwise specified.

[0044] Example 1

[0045] A preparation method of a high-stability copper gold powder pigment is as follows:

[0046] S1, in-situ passivation-ball milling refinement: 100 parts by weight of copper-zinc alloy coarse powder, 600 parts by weight of zirconium oxide grinding ball and 2 parts by weight of stearic acid are put into a planetary ball mill; 200 parts by weight of anhydrous isopropyl alcohol is used to dissolve the compound passivator (2-amino benzothiazole 1 part by weight, diethanolamine molybdate 0.8 part by weight), and after stirring for 30 min, it is added to the ball mill. Nitrogen gas is used to replace air three times. Under the nitrogen atmosphere, uniform speed controlled temperature ball milling is carried out at 80 rpm, 50°C and for 18 h. After discharging, screening is carried out through a 100 mesh screen. Anhydrous isopropyl alcohol is used for washing twice, and suction filtration is carried out to obtain an amino-functionalized passivation substrate (surface enriched with -NH2 groups);

[0047] S2, silane coupling enhanced SiO2 barrier layer: 50 parts by weight of the base material prepared in step S1 was dispersed in 300 parts by weight of anhydrous isopropyl alcohol, stirred and dispersed for 10 min, 10 parts by weight of deionized water was added, triethanolamine 3 parts by weight, heated to 70°C, 8 parts by weight of tetraethyl orthosilicate and 2 parts by weight of phenyltriethoxysilane were dissolved in 40 parts by weight of anhydrous isopropyl alcohol, slowly added dropwise within 5h, reacted at 70°C for 3h, after suction filtration, washed once with anhydrous isopropyl alcohol, to obtain a phenyl-modified SiO2 coated intermediate (surface residual ethoxyl group Si-O-C2H5);

[0048] S3, chemically bonded outer layer modification: the intermediate in step S2 was dispersed in 150 parts by weight of anhydrous isopropyl alcohol, heated to 60°C and stirred, and the compounded stabilizer (3- (glycidyl ether oxy) propyl trimethoxysilane 1.5 parts by weight, amino propyl terminated polydimethylsiloxane 2.0 parts by weight) was weighed and dissolved in 50 parts by weight of anhydrous isopropyl alcohol, and then added dropwise to the system after pre-reaction for 30 min, reacted for 3h, washed with anhydrous isopropyl alcohol after centrifugation, and vacuum dried at 60°C for 6h to obtain copper-gold powder pigment.

[0049] Example 2

[0050] A method for preparing a high-stability copper-gold powder pigment, specifically as follows:

[0051] S1, in-situ passivation-ball milling refinement: 100 parts by weight of copper-zinc alloy coarse powder, 600 parts by weight of zirconia grinding balls, and 2.5 parts by weight of stearic acid were put into a planetary ball mill; 200 parts by weight of anhydrous isopropyl alcohol was taken, and a compounded passivation agent (2-amino benzothiazole 1.2 parts by weight, diethanolamine molybdate 1.0 parts by weight) was dissolved, stirred for 30 min, and then added to the ball mill, nitrogen was filled to replace air three times, and the ball mill was operated at a uniform speed and controlled temperature: 80 rpm, 50°C, 18h; after discharging, sieving was performed through a 100 mesh sieve, and anhydrous isopropyl alcohol was washed twice, and suction filtration was performed to prepare an amino-functionalized passivated base material (surface enriched with -NH2 groups);

[0052] S2, silane coupling enhanced SiO2 barrier layer: 50 parts by weight of the base material prepared in step S1 was dispersed in 300 parts by weight of anhydrous isopropyl alcohol, stirred and dispersed for 10 min, 10 parts by weight of deionized water was added, triethanolamine 3 parts by weight, heated to 70°C, 8 parts by weight of tetraethyl orthosilicate and 2 parts by weight of phenyltriethoxysilane were dissolved in 40 parts by weight of anhydrous isopropyl alcohol, slowly added dropwise within 5h, reacted at 70°C for 3h, after suction filtration, washed once with anhydrous isopropyl alcohol, to obtain a phenyl-modified SiO2 coated intermediate (surface residual ethoxyl group Si-O-C2H5);

[0053] S3, chemical bonding type outer layer modification: the step S2 intermediate is dispersed in 150 parts by weight of anhydrous isopropyl alcohol, heated to 60°C and stirred, weighed and compounded stabilizer (3- (glycidyl ether oxy) propyl trimethoxysilane 1.5 parts by weight, amino propyl terminated polydimethylsiloxane 2.0 parts by weight) is dissolved in 50 parts by weight of anhydrous isopropyl alcohol, and then added dropwise into the system after pre-reaction for 30 min, and reacted for 3 hours. After centrifugation, anhydrous isopropyl alcohol is washed, and vacuum drying at 60°C for 6h obtains copper gold powder pigment.

[0054] Example 3

[0055] A method for preparing a high-stability copper gold powder pigment, specifically as follows:

[0056] S1, in-situ passivation-ball milling refining: take 100 parts by weight of copper-zinc alloy coarse powder, 600 parts by weight of zirconia grinding balls and 3 parts by weight of stearic acid into a planetary ball mill; take 200 parts by weight of anhydrous isopropyl alcohol, dissolve the compounded passivation agent (2-amino benzothiazole 2.5 parts by weight, diethanolamine molybdate 1.5 parts by weight), and then add into the ball mill after stirring for 30 min, replace the air with nitrogen three times, and ball mill at a constant speed: 80 rpm, 50°C, 18h; after discharging, screen through a 100 mesh sieve, wash twice with anhydrous isopropyl alcohol, and then extract to obtain the amino functionalized passivation substrate (surface enriched with -NH2 groups);

[0057] S2, silane coupling enhanced SiO2 barrier layer: disperse 50 parts by weight of the substrate prepared in step S1 in 300 parts by weight of anhydrous isopropyl alcohol, stir and disperse for 10 min, add 12 parts by weight of deionized water and triethanolamine 8 parts by weight, heat to 70°C, weigh and dissolve tetraethyl orthosilicate 12 parts by weight and phenyl triethoxysilane 0.5 parts by weight in 40 parts by weight of anhydrous isopropyl alcohol, slowly dropwise add within 5h, and react at 70°C for 3h, wash once with anhydrous isopropyl alcohol after extraction, and obtain the phenyl modified SiO2 coated intermediate (surface residual ethoxy Si-O-C2H5);

[0058] S3, chemical bonding type outer layer modification: the step S2 intermediate is dispersed in 150 parts by weight of anhydrous isopropyl alcohol, heated to 60°C and stirred, weighed and compounded stabilizer (3- (glycidyl ether oxy) propyl trimethoxysilane 1.5 parts by weight, amino propyl terminated polydimethylsiloxane 2.0 parts by weight) is dissolved in 50 parts by weight of anhydrous isopropyl alcohol, and then added dropwise into the system after pre-reaction for 30 min, and reacted for 3 hours. After centrifugation, anhydrous isopropyl alcohol is washed, and vacuum drying at 60°C for 6h obtains copper gold powder pigment.

[0059] Example 4

[0060] A method for preparing a high-stability copper gold powder pigment, specifically as follows:

[0061] S1, in-situ passivation-ball milling finishing: take 100 parts by weight of copper-zinc alloy coarse powder, 600 parts by weight of zirconium oxide grinding ball, 2.5 parts by weight of stearic acid into the planetary ball mill; take 200 parts by weight of anhydrous isopropyl alcohol, dissolve the compounded passivation agent (2-amino benzothiazole 1.2 parts by weight, diethanolamine molybdate 1.0 parts by weight), after stirring for 30 min, add into the ball mill, replace air with nitrogen three times, according to three-stage variable speed control temperature ball milling: stage one: 90 rpm, 50℃, 4h; stage two: 72 rpm, 45℃, 11h; stage three: 55 rpm, 40℃, 3h; after discharging, screen through 100 mesh sieve, wash twice with anhydrous isopropyl alcohol, and then filter under vacuum to obtain the amino functionalized passivation substrate (surface enriched with -NH2 groups);

[0062] S2, silane coupling enhanced SiO2 barrier layer: disperse 50 parts by weight of the substrate prepared in step S1 in 300 parts by weight of anhydrous isopropyl alcohol, stir and disperse for 10 min, add 12 parts by weight of deionized water, and 5 parts by weight of catalyst triethanolamine, heat to 70℃, weigh 9 parts by weight of tetraethyl orthosilicate and 1 part by weight of phenyl triethoxysilane dissolved in 40 parts by weight of anhydrous isopropyl alcohol, slowly dropwise add within 5h, react at 70℃ for 3h, after filtering under vacuum, wash once with anhydrous isopropyl alcohol to obtain the phenyl modified SiO2 coated intermediate (surface residual ethoxy Si-O-C2H5);

[0063] S3, chemical bonding type outer layer modification: disperse the intermediate in step S2 in 150 parts by weight of anhydrous isopropyl alcohol, heat to 60℃ and stir, weigh the compounded stabilizer (3- (glycidyl ether oxy) propyl trimethoxysilane 1.5 parts by weight, amino propyl terminated polydimethylsiloxane 2.0 parts by weight), dissolve in 50 parts by weight of anhydrous isopropyl alcohol, pre-react for 30 min, then dropwise add to the system, react for 3h, after centrifugation, wash with anhydrous isopropyl alcohol, and then vacuum dry at 60℃ for 6h to obtain the copper gold powder pigment.

[0064] In order to study the effects of different passivation agents / compounded passivation agents and stabilizers / compounded stabilizers on the properties of the copper gold powder pigment, the technical solutions of comparative examples 1-8 are also designed, as follows:

[0065] Comparative example 1

[0066] In this comparative example, the composition of the compounded passivation agent in step S1 of example 4 is adjusted, and after adjustment, a single passivation agent is used; 2-amino benzothiazole is 2.2 parts by weight.

[0067] The rest are consistent with example 4.

[0068] Comparative example 2

[0069] In this comparative example, the compounded passivator ingredient in Step S1 of Example 4 was adjusted to a single passivator: diethanolamine molybdate 2.2 parts.

[0070] The rest were kept the same as Example 4.

[0071] Comparative Example 3

[0072] In this comparative example, the compounded stabilizer ingredient in Step S1 of Example 4 was adjusted to a single stabilizer: 3-(glycidyloxy)propyltrimethoxysilane 3.5 parts.

[0073] The rest were kept the same as Example 4.

[0074] Comparative Example 4

[0075] In this comparative example, the compounded stabilizer ingredient in Step S1 of Example 4 was adjusted to a single stabilizer: aminopropyl-terminated polydimethylsiloxane 3.5 parts.

[0076] The rest were kept the same as Example 4.

[0077] Comparative Example 5

[0078] In this comparative example, the compounded passivator ingredient in Step S1 of Example 4 was adjusted to a compounded passivator: 2-aminobenzothiazole 1.2 parts by weight, citric acid 1.0 part by weight.

[0079] The rest were kept the same as Example 4.

[0080] Comparative Example 6

[0081] In this comparative example, the compounded passivator ingredient in Step S1 of Example 4 was adjusted to a compounded passivator: benzotriazole 1.2 parts by weight, diethanolamine molybdate 1.0 part by weight.

[0082] The rest were kept the same as Example 4.

[0083] Comparative Example 7

[0084] In this comparative example, the compounded stabilizer ingredient in Step S3 of Example 4 was adjusted to a compounded stabilizer: 3-(glycidyloxy)propyltrimethoxysilane 1.5 parts by weight, hydroxyl-terminated polydimethylsiloxane 2.0 parts by weight.

[0085] The rest were kept the same as Example 4.

[0086] Comparative Example 8

[0087] In the present comparative example, the compounding stabilizer component in step S3 of Example 4 was adjusted to be 1.5 parts by weight of γ-methacryloxypropyltrimethoxysilane and 2.0 parts by weight of aminopropyl-terminated polydimethylsiloxane.

[0088] The rest were consistent with Example 4.

[0089] Comparative Example 9

[0090] In the present comparative example, the preparation method of Example 4 was adjusted by omitting step S2; the rest were consistent with Example 4.

[0091] Comparative Example 10

[0092] In the present comparative example, the preparation method of Example 4 was adjusted by omitting step S3; the rest were consistent with Example 4.

[0093] Comparative Example 11

[0094] In the present comparative example, the preparation method of Example 4 was adjusted by omitting steps S2 and S3; the rest were consistent with Example 4.

[0095] (1) Gloss performance test

[0096] The copper-gold powder prepared in Examples 1-4 and Comparative Examples 1-11 above was taken respectively, and the amount of copper-gold powder in the color paint was 5-15 wt%. The copper-gold powder, the dispersion (ethylene glycol butyl ether), and the varnish (water-based polyurethane resin) were mixed uniformly according to a mass ratio of 1:1.5:7.5 to obtain the corresponding paint sample. A four-sided coater was used to prepare a 50 μm paint film on a sample plate. After drying at room temperature, a BYK 60° gloss meter was used to detect the data. After calibration, 5 points were tested on each plate, and the average value was taken. The experimental data are shown in Table 1:

[0097] Table 1 Gloss experimental data record

[0098] ;

[0099] (2) Salt spray resistance performance test

[0100] The copper-gold powder prepared in the above Examples 1-4 and Comparative Examples 1-11 was taken respectively, and the amount of the copper-gold powder in the color paint was 5-15 wt%. In this experiment, the copper-gold powder, the dispersion (ethylene glycol butyl ether), and the varnish (water-based acrylic resin) were mixed uniformly at a mass ratio of 1:1.5:7.5, and then deionized water was added (the mass ratio of the copper-gold powder to the deionized water was 1:3) to adjust the viscosity, thereby obtaining a corresponding paint sample. The paint sample was first sprayed on a cleaned tin plate (70x150x1mm) with an epoxy primer (about 20μm), and then the tin plate was placed in a room temperature for 24 hours for curing. Then, the copper-gold powder coating (about 30μm) was sprayed on the tin plate, and the tin plate was dried at 150℃ for 30 minutes. The coating was subjected to the following tests based on the joint test scheme and rating process of the salt spray test (GB / T 10125-1997) and the evaluation of the corrosion resistance of the paint and varnish coating (GB / T 30789-2015):

[0101] Experimental conditions: The test was carried out in a BGD881 salt spray corrosion test chamber, and the continuous spraying mode was used, and the duration was 240 hours. The test temperature was controlled at 35±1℃, and 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), with a pH of 6.5-7.2, a distilled water conductivity of 1.76 mS / m, and a salt spray deposition amount of 1.0-2.0 mL / 80 cm 2 . The air pressure in the chamber was maintained at 1.0 kPa, and the relative humidity was ≤85%. The test sample was placed in the chamber at an inclination angle of 15°.

[0102] ① Adhesion loss (peeling area of the coating / %): salt spray after crosshatch method (GB / T 9286), and the calculation formula was as follows:

[0103] Loss rate = { (initial adhesion - adhesion after salt spray) / initial adhesion} x 100%;

[0104] ② Color difference ΔE: L, a, b values were measured at 5 points before and after salt spray, and the calculation formula was as follows:

[0105] ΔE= ;

[0106] ③ Bubble density: the number of bubbles in an area of 1 cm 2 was observed under a microscope, and the calculation formula was as follows:

[0107] Bubble density (pieces / cm 2 ) = total number of bubbles / observed area;

[0108] The evaluation criteria for cracking grade were shown in Table 2:

[0109] Table 2 Evaluation criteria for cracking grade

[0110] ;

[0111] The rating criteria for the corrosion rating (Ri) are shown in Table 3:

[0112] Table 3 Rating criteria for the corrosion rating (Ri)

[0113] ;

[0114] The salt spray resistance test data of the copper-gold powder pigment samples of Examples 1-4 and Comparative Examples 1-11 above are shown in Table 4:

[0115] Table 4 Salt spray resistance test data record table

[0116] ;

[0117] (3) Storage resistance test

[0118] The copper-gold powders prepared in Examples 1-4 and Comparative Examples 1-11 above were each taken in an amount of 5-15 wt% in the color paint, and the present experiment was mixed uniformly according to the mass ratio of “copper-gold powder: dispersion (ethylene glycol butyl ether): varnish (water-based polyurethane resin) = 1:1.5:7.5” to prepare the corresponding paint samples. A four-sided applicator was used to prepare a paint film with a wet film thickness of 50 μm on a substrate sample, and after the paint film was completely dried at room temperature, a pre-calibrated BYK 60° gloss meter was used for detection. Five test points were selected on each sample, and the average value of the data of each test point was taken as the initial gloss data of the paint sample (as shown in Table 1).

[0119] Subsequently, 50 g of the copper-gold powder of each of Examples 1-4 and Comparative Examples 1-11 was weighed into a No. 5 self-sealing bag, which was sealed, and the sealed self-sealing bag was then placed in a tin can for secondary sealing. The secondary sealed copper-gold powder sample was placed in a forced ventilation 75°C constant temperature oven for continuous light-avoiding storage for 90 days to complete the heat storage experiment.

[0120] After the heat storage experiment was completed, the copper-gold powder sample was taken out and mixed uniformly according to the mass ratio of “copper-gold powder: dispersion (ethylene glycol butyl ether): varnish (water-based polyurethane resin) = 1:1.5:7.5” to prepare the corresponding paint samples after heat storage. The above paint film preparation and gloss detection steps (wet film thickness 50 μm, room temperature drying, BYK 60° gloss meter calibration after 5-point average value measurement) were repeated to obtain the gloss data of the paint samples after heat storage.

[0121] According to the gloss data and color parameters of the paint samples before and after heat storage, the color difference value ΔE, the yellow-blue difference value (Δb*) and the gloss retention rate (GR) corresponding to each copper-gold powder sample before and after heat storage were calculated as follows:

[0122] ① Color difference ΔE: 5 points before and after heat storage, L, a, b values are measured, and the calculation formula is as follows:

[0123] ΔE= ;

[0124] ② Δb*: 5 points before and after heat storage, b value is measured, and the calculation formula is as follows:

[0125] Δb*=b 热储后 -b 基准 ;

[0126] ③ The calculation formula of gloss retention rate is: GR (%) = (G 热储后 / G 基准 ) x 100%;

[0127] The storage resistance performance test data of the copper-gold powder pigment samples of Examples 1-4 and Comparative Examples 1-11 are shown in Table 5:

[0128] Table 5 Storage resistance performance test data record table

[0129] ;

[0130] The conclusions based on the above experiments are as follows:

[0131] The "in-situ passivation-milling" integrated process of the application: the traditional step-by-step ball milling shaping and surface passivation are combined into one, and in the ball milling process, the continuously exposed fresh metal surface is reacted with the compounded passivation reagent (2-amino benzothiazole and diethanolamine molybdate) synchronously, and a uniform, dense and firmly combined "organic-inorganic" compounded passivation layer is formed in-situ. This process is the basis for all subsequent properties.

[0132] Structure design of multi-layer compounded protection system: a triple synergistic protection architecture of "chemical passivation layer (inner layer)-silicon dioxide dense barrier layer (middle layer)-space stabilization layer (outer layer)" is successfully constructed. This structure design realizes multiple and progressive protection from chemical corrosion, physical isolation to space steric stabilization, and systematically solves the limitations of single protection means.

[0133] Compounded passivation agent and its synergistic effect: 2-amino benzothiazole and diethanolamine molybdate are compounded, which produces a synergistic effect of "chemical adsorption + oxidation film formation", and its effect is much better than other compounded passivation agents or single passivation agents, indicating that there is a synergistic effect between them.

[0134] The complex stabilizer and its synergistic effect: the complex of 3-(glycidyloxy)propyltrimethoxysilane and amino-terminated polydimethylsiloxane forms a stable outer layer connected by chemical reaction through covalent bond, providing extreme spatial stability based on the principle of entropy repulsion, which is much better than other complex stabilizers or single stabilizers, indicating that there is a synergistic effect between them.

[0135] Variable speed temperature control ball milling process: adopt three-stage variable speed ball milling strategy (high speed impact, medium speed grinding, low speed polishing / passivation) and match accurate rotation speed, time and temperature parameters, to ensure that high flakiness, low surface defect base material is obtained, and efficient and uniform passivation layer is realized.

[0136] The present application forms an organic chelation and inorganic oxidation composite film in the inner layer, enhances the intrinsic corrosion resistance of the substrate; the phenyl-modified silica in the middle layer introduces molecular-level flexibility while maintaining the dense barrier properties, improves the brittle fracture tendency of traditional pure silica layer, and the anti-cracking performance is significantly improved; the outer layer of epoxy-amino siloxane crosslinking network provides dynamic protection, significantly delays the color fading in harsh environment, and makes the product maintain optical and chemical stability for a long time under the conditions of humidity, salt spray and the like.

[0137] In terms of application performance, the interlayer is connected by Si-N bond, Si-O-C ether bond and hydrogen bond network, which greatly improves the interlayer bonding force and wear resistance; the steric hindrance effect effectively inhibits storage aggregation, and the powder flowability and dispersibility are obviously optimized, which can be directly applied to high-end printing scenes; in the field of sustainability, the whole process of single water-free isopropyl alcohol solvent design simplifies the recovery process and reduces environmental load; the heavy metal-free formula considers safety and regulatory compliance, and gives the product a broader application prospect; this multi-dimensional innovation provides a copper and gold powder solution for the high-end packaging field with long-term protection, visual performance and ecological friendly features.

[0138] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent of the present application. 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. A method for preparing a highly stable copper-gold powder pigment, characterized in that: Includes the following steps: S1. Take copper-zinc alloy coarse powder and stearic acid and put them into a ball mill; use anhydrous isopropanol to dissolve the compound passivating agent, stir evenly and add it into the ball mill. Under nitrogen atmosphere, after ball milling, the ball milling product is obtained. After sieving, washing and filtering, the ball milling product is used to obtain an amino-functionalized passivated substrate. The compound passivating agent comprises 2-aminobenzothiazole and diethanolamine molybdate in a mass ratio of 0.5-2:1; The ball mill is a variable speed temperature controlled ball mill, which is a three-stage variable speed temperature controlled ball mill, wherein: Stage 1: 85-95 rpm, 40-60℃, 3-5h; Stage 2: 65-80 rpm, 40-50℃, 8-13h; Stage 3: 50-60 rpm, 35-45℃, 2-4h; S2. The amino-functionalized passivated substrate obtained in step S1 is dispersed in anhydrous isopropanol to obtain a reaction system. Deionized water and catalyst are added and the temperature is raised. Tetraethyl orthosilicate and phenyltriethoxysilane are dissolved in anhydrous isopropanol and slowly added to the reaction system. The reaction is kept at a constant temperature and then filtered and washed to obtain a phenyl-modified SiO2-coated intermediate. S3. The phenyl-modified SiO2-coated intermediate obtained in step S2 is dispersed in anhydrous isopropanol to obtain a mixed system. The mixture is heated and stirred. The compound stabilizer is dissolved in anhydrous isopropanol and added dropwise to the mixed system after a certain reaction time. After centrifugation, washing, and vacuum drying, copper-gold powder pigment is obtained. The compound stabilizer comprises 3-(glycidyl etheroxy)propyltrimethoxysilane and aminopropyl-terminated polydimethylsiloxane in a mass ratio of 0.5-1.5:

1.

2. The method for preparing a highly stable copper-gold powder pigment according to claim 1, characterized in that: In step S1, the mass ratio of the copper-zinc alloy coarse powder, stearic acid, and compound passivating agent is 100:2-3:2-4; The mass ratio of the compound passivating agent to anhydrous isopropanol is 0.5-2:

100.

3. The method for preparing a highly stable copper-gold powder pigment according to claim 1, characterized in that: In step S2, by weight, it includes 45-55 parts of amino-functionalized passivated substrate, 10-15 parts of deionized water, 3-8 parts of catalyst, 8-15 parts of tetraethyl orthosilicate, and 0.5-2 parts of phenyltriethoxysilane.

4. The method for preparing a highly stable copper-gold powder pigment according to claim 3, characterized in that: The mass ratio of the amino-functionalized passivated substrate to anhydrous isopropanol is 1:5-7; the mass ratio of the total mass of tetraethyl orthosilicate and phenyltriethoxysilane to anhydrous isopropanol is 1:3-4.

5.

5. The method for preparing a highly stable copper-gold powder pigment according to claim 1, characterized in that: In step S2, the reaction temperature is 65-80℃ and the reaction time is 2-10h.

6. The method for preparing a highly stable copper-gold powder pigment according to claim 1, characterized in that: The mass ratio of the phenyl-modified SiO2-coated intermediate to anhydrous isopropanol is 1:2-4; The mass ratio of the phenyl-modified SiO2-coated intermediate to the compound stabilizer is 50:2-5.

7. The method for preparing a highly stable copper-gold powder pigment according to claim 1, characterized in that: In step S3, the reaction temperature is 55-70℃ and the reaction time is 2-5h.

8. A highly stable copper-gold powder pigment, characterized in that: It is prepared by any one of the preparation methods described in claims 1-7.

9. The application of the high-stability copper-gold powder pigment as described in claim 8 in the preparation of high-performance paints, characterized in that: The high-performance paint has high metallic luster, chemical corrosion resistance, and high storage stability.

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