Bronze electrolytic coloring liquid for aluminum products and its application

Abstract

The present invention relates to the field of aluminum alloy surface technical treatment, in particular to the field of IPC C25D, and more specifically to a bronze electrolytic coloring liquid for aluminum products and its application. The raw materials for preparing the bronze electrolytic coloring liquid for aluminum products at least include 10-20 g / L copper salt, 5-25 g / L sulfophthalic acid, 0.5-2 g / L sulfide, 20-30 g / L conductive salt, and 10-30 g / L acid. The electrolytic coloring liquid used in the present invention breaks through the traditional aluminum copper salt electrolytic coloring red system, obtains a new bronze color system, and the coloring film prepared by a specific process has high adhesion, uniform coating, good glossiness, excellent weather resistance, and expands the color system of copper salt aluminum electrolytic coloring.

Description

Technical Field

[0001] The invention relates to the field of aluminum alloy surface technical treatment, in particular to the field of IPC C25D, and more specifically to a bronze electrolytic coloring liquid for aluminum products and application thereof. Background Art

[0002] After anodizing and electrolytic coloring of aluminum, the weather resistance, wear resistance and light resistance of aluminum can be improved. At present, the aluminum alloys used for coloring are mainly solid colors and bronze colors. The electrolytic coloring liquid used is generally tin salt or nickel salt. The bath liquid has good dispersibility and the film layer has a uniform and stable color tone. Electrolytic coloring of copper salts is generally used to make a red appearance. The color system is single and cannot meet the needs of most scenes.

[0003] In the prior art, the patent with application number CN202110475449.3 discloses a black electrolytic coloring additive for aluminum profiles and its coloring process, which selects metal antimony salt as the auxiliary coloring salt to adjust the color of the coloring film from sub-black (bluish) to pure black (true black), but it cannot obtain a bronze-colored coloring film.

[0004] The patent with application number CN202010310930.2 discloses a method for coloring the surface of a material, which can obtain colorful coloring layers such as pink, grass green, yellow-green, blue-purple, purple-red, orange-yellow, and orange-red, but cannot obtain a bronze-colored coloring film. Summary of the invention

[0005] In order to solve the above problems, the first aspect of the present invention provides a bronze electrolytic coloring liquid for aluminum products, wherein the bronze electrolytic coloring liquid for aluminum products comprises at least 10-20 g / L copper salt, 5-25 g / L sulfophthalic acid, 0.5-2 g / L sulfide, 20-30 g / L conductive salt, 10-30 g / L acid, and solvent.

[0006] Preferably, the solvent is deionized water.

[0007] Preferably, the bronze electrolytic coloring liquid for aluminum products comprises at least 10-20 g / L copper salt, 5-15 g / L sulfophthalic acid, 0.5-2 g / L sulfide, 20-25 g / L conductive salt, and 10-20 g / L acid.

[0008] Preferably, the concentration ratio of the copper salt to the sulfide is (5-30):1.

[0009] Preferably, the copper salt comprises copper sulfate pentahydrate.

[0010] Preferably, the sulfide includes one or more of sodium thiosulfate, sodium sulfide, thiourea, and thiosemicarbazide; further preferably, it is thiourea.

[0011] The inventors of the present invention have creatively discovered that by selecting specific sulfides and copper salts and limiting their concentration ratios, the coloring color of the coloring liquid can be changed while not affecting the performance of the coloring film finally obtained. This may be because, on the one hand, the specific sulfides can react with copper salts to reduce divalent copper to monovalent copper, thereby making the copper salt coloring film, which should normally be reddish, black, and making the film layer appear bronze. On the other hand, the specific concentrations of copper sulfate and thiourea can adjust the color tone while ensuring the coloring dispersion. In addition, the specific concentration can also accelerate the speed of coloring film formation without affecting its coloring uniformity, thereby improving production efficiency. The coloring rate is faster at a higher concentration, but although the coloring will turn black quickly if the concentration is too high, copper hydroxide is likely to adhere when the time is extended, affecting the coloring effect.

[0012] Preferably, the conductive salt includes one or more of magnesium sulfate heptahydrate, aluminum sulfate, and magnesium acetate; further preferably, it is magnesium sulfate heptahydrate.

[0013] The inventors unexpectedly discovered that the use of magnesium sulfate heptahydrate at a specific concentration as a conductive salt can reduce the internal resistance of the solution, prevent the coloring film from falling off at a higher coloring voltage, and inhibit the influence of harmful ions on the formation of the coloring film. It can also work with other components to ensure that the prepared electrolytic coloring liquid has good stability, the prepared coloring film has high adhesion to the substrate, the coating is uniform, the gloss is good, and it has excellent weather resistance.

[0014] Preferably, the acid includes one or more of sulfuric acid and boric acid; further preferably, it is sulfuric acid.

[0015] The inventors unexpectedly discovered that the synergistic effect of selecting a specific concentration of sulfophthalic acid and sulfuric acid can prevent the hydrolysis of copper salts, while ensuring the stability of the coloring liquid, and can also improve the conductivity of the coloring liquid. On the other hand, it can improve the dispersibility of the coloring liquid, thereby improving the uniformity of the color, and improve the weather resistance of the coloring film. In addition, the adjustment of the sulfuric acid concentration can also cooperate with the copper salt to adjust the lightness and darkness of the color of the coloring film.

[0016] Preferably, the method for preparing the bronze electrolytic coloring liquid for aluminum products is: mixing the preparation raw materials evenly.

[0017] Preferably, the use temperature of the bronze electrolytic coloring liquid for aluminum products is 18-22°C.

[0018] The second aspect of the present invention provides the application of the bronze electrolytic coloring liquid for aluminum products, which is applied to prepare a coloring film.

[0019] The specific preparation method of the colored film is:

[0020] S1. Pre-treat the substrate: degrease, alkali wash, neutralize and then wash the aluminum material in sequence;

[0021] S2. Anodizing: Anodizing the pre-treated aluminum material;

[0022] S3. Coloring treatment: immerse the anodized aluminum material in an electrolytic coloring solution, and perform electrolytic coloring at 18-22°C using a 40-60Hz AC power supply, with an electrolytic voltage of 14-18V and a coloring time of 0.5-5min.

[0023] Preferably, the degreasing agent is a sulfuric acid solution with a concentration of 150-200 g / L, and the degreasing time is 3-7 min.

[0024] Preferably, the alkaline cleaning agent is a sodium hydroxide solution with a concentration of 30-50 g / L, the alkaline cleaning time is 3-7 min, and the alkaline cleaning temperature is 50-70°C.

[0025] Preferably, the neutralizing agent is a sulfuric acid solution with a concentration of 150-200 g / L, and the neutralization time is 1-5 min.

[0026] Preferably, the specific steps of the anodizing are: placing the aluminum material in a sulfuric acid solution with a concentration of 180-200 g / L for anodizing; the parameters of the anodizing are: current density 0.9-1.3 A / dm 2 , electrolysis temperature 15-25℃, processing time 20-30min.

[0027] Beneficial effects:

[0028] 1. The present invention selects specific sulfides and copper salts and limits their concentration ratio, thereby being able to change the coloring color of the coloring liquid without affecting the performance of the coloring film finally obtained.

[0029] 2. The present invention selects sulfophthalic acid and sulfuric acid at specific concentrations, which can improve the conductive properties of the coloring liquid while ensuring the stability of the coloring liquid, and can also improve the color uniformity and weather resistance of the coloring film.

[0030] 3. The present invention uses magnesium sulfate heptahydrate of a specific concentration as the conductive salt, which can improve the adhesion of the coloring film.

[0031] 4. The electrolytic coloring liquid used in the present invention breaks through the traditional red coloring of aluminum copper salt electrolytic coloring and obtains a new bronze coloring system. The coloring film prepared by a specific process has high adhesion, uniform coating, good glossiness, and excellent weather resistance, which expands the color system of copper salt aluminum electrolytic coloring. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1is a picture of the colored film prepared in Example 1; the numbers a, b, c, d, e, f, g, h, i, j, k, and l in the picture correspond to the colored films a, b, c, d, e, f, g, h, i, j, k, and l in Example 1;

[0033] Figure 2 This is a picture of the colored film prepared in Comparative Example 1; the numbers a, b, c, d, e, f, g, h, i, j, k, and l in the figure correspond to the colored films a, b, c, d, e, f, g, h, i, j, k, and l in Comparative Example 1;

[0034] Figure 3 These are pictures (b) of the colored film plated on the surface of the fishing gear workpiece according to scheme i in Example 1 and (a) of the colored film plated on the surface of the fishing gear workpiece according to scheme i in Comparative Example 1. DETAILED DESCRIPTION

[0035] Example

[0036] Example 1

[0037] Example 1 provides a bronze electrolytic coloring liquid for aluminum products. The raw materials and related concentrations of the bronze electrolytic coloring liquid for aluminum products are shown in Table 1. a, b, c, d, e, f, g, h, i, j, k, and l in the table represent colored films prepared with different thiourea concentrations and coloring times. The solvent is deionized water. The preparation method of the colored film is:

[0038] S1. Pre-treat the substrate: degrease, alkali wash, neutralize and then wash the aluminum material in sequence;

[0039] S2. Anodizing: Anodizing the pre-treated aluminum material;

[0040] S3. Coloring treatment: immerse the anodized aluminum material in an electrolytic coloring solution, and electrolytically color it at 20°C using a 50Hz AC power supply. The electrolytic voltage is 16V, and the coloring time is shown in Table 1.

[0041] The raw materials and relevant concentrations of the electrolytic coloring solution are shown in Table 1.

[0042] The degreasing agent is a sulfuric acid solution with a concentration of 180 g / L, and the degreasing time is 5 minutes.

[0043] The alkaline cleaning agent is a sodium hydroxide solution with a concentration of 40 g / L, the alkaline cleaning time is 5 minutes, and the alkaline cleaning temperature is 60°C.

[0044] The neutralizing agent is a sulfuric acid solution with a concentration of 170 g / L, and the neutralization time is 3 minutes.

[0045] The specific steps of the anodizing are: placing the aluminum material in a sulfuric acid solution with a concentration of 190 g / L for anodizing. The anodizing parameters are: current density 1.1 A / dm 2 , electrolysis temperature 20℃, treatment time 25min.

[0046] Table 1

[0047]

[0048]

[0049] The photos of the colored films prepared with different coloring time and thiourea concentration are shown in Figure 1 As shown, from Figure 1 It can be seen that the addition of thiourea can make the colored film present a unique bronze color, but the higher the thiourea concentration, the more limited the effect on the depth of coloring. When the thiourea concentration is 5g / L, 15g / L, and 30g / L, the prepared colored film is lighter in color. In this system, the coloring time is 60s, i.e. 1min, and the thiourea concentration is 1g / L to obtain a darker bronze colored film.

[0050] Comparative Example 1

[0051] Comparative Example 1 provides a bronze electrolytic coloring liquid for aluminum products, and the specific implementation method is the same as that of Example 1, except that thiourea is not included. The raw materials and related concentrations of the bronze electrolytic coloring liquid for aluminum products are shown in Table 2. a, b, c, d, e, f, g, h, i, j, k, and l in the table all represent coloring films prepared by different anhydrous copper sulfate concentrations and coloring times, and the solvents are all deionized water.

[0052] Table 2

[0053]

[0054] The photos of the colored films prepared with different coloring time and copper sulfate concentration are shown in Figure 2 As shown, from Figure 2 It can be seen that the coloring film prepared by the coloring liquid with only copper salt without adding thiourea is red, and the higher the concentration of anhydrous copper sulfate and the longer the coloring time, the darker the color of the prepared coloring film, but it is still red and black, and will not show a bronze color.

[0055] Comparative Example 2

[0056] Comparative Example 2 provides a bronze electrolytic coloring liquid for aluminum products. The specific implementation method is the same as that of Example 1, except that the raw materials for preparing the bronze electrolytic coloring liquid for aluminum products are: 15 g / L copper sulfate pentahydrate, 1 g / L sulfophthalic acid, 1 g / L thiourea, 20 g / L magnesium sulfate heptahydrate, and 15 g / L sulfuric acid.

[0057] Comparative Example 3

[0058] Comparative Example 3 provides a bronze electrolytic coloring liquid for aluminum products. The specific implementation method is the same as that of Example 1, except that the raw materials for preparing the bronze electrolytic coloring liquid for aluminum products are: 15 g / L copper sulfate pentahydrate, 10 g / L sulfophthalic acid, 1 g / L thiourea, 20 g / L magnesium sulfate heptahydrate, and 5 g / L sulfuric acid.

[0059] Performance Testing

[0060] 1. Adhesion test

[0061] For the colored oxide films prepared in Example 1 i and Comparative Examples 2-3, the adhesion of the conductive coating was tested by the 100-grid method according to GB9286, and a non-falling rate (number of non-falling grids / total number of grids*100%) ≥ 95% was recorded as excellent, a non-falling rate of 85% ≤ < 95% was recorded as good, and a non-falling rate of 75% ≤ < 85% was recorded as unqualified. The results are recorded in Table 3.

[0062] 2. Weather resistance test

[0063] The colored oxide films prepared in Example 1 i and Comparative Examples 2-3 were placed outdoors and their adhesion was tested after 60 days. If the adhesion remained the same as that 60 days ago, it was considered to have passed the weather resistance test. The results are recorded in Table 3.

[0064] Table 3

[0065] Adhesion Weather resistance In Example 1 excellent qualified Comparative Example 2 excellent Failure Comparative Example 3 good Failure

Claims

1. A bronze electrolytic coloring liquid for aluminum products, It is characterized in that The bronze electrolytic coloring liquid for aluminum products at least comprises 10-20 g / L copper salt, 5-15 g / L sulfophthalic acid, 0.5-2 g / L sulfide, 20-25 g / L conductive salt, 10-20 g / L acid, and solvent; The copper salt includes copper sulfate pentahydrate; The sulfide is thiourea; The acid is sulfuric acid; The concentration ratio of the copper salt to the sulfide is (5-30):

1.

2. The bronze electrolytic coloring liquid for aluminum products according to claim 1, It is characterized in that The conductive salt includes one or more of magnesium sulfate heptahydrate, aluminum sulfate, and magnesium acetate.

3. The bronze electrolytic coloring liquid for aluminum products according to claim 1, It is characterized in that The use temperature of the bronze electrolytic coloring liquid for aluminum products is 18-22°C.

4. An application of the bronze electrolytic coloring liquid for aluminum products according to any one of claims 1 to 3, It is characterized in that Used in the preparation of colored films.

5. Application of bronze electrolytic coloring liquid for aluminum products according to claim 4, It is characterized in that The specific preparation method of the colored film is: S1. Pre-treat the substrate: degrease, alkali wash, neutralize and then wash the aluminum material in sequence; S2. Anodizing: Anodizing the pre-treated aluminum material; S3. Coloring treatment: immerse the anodized aluminum material in an electrolytic coloring solution, and perform electrolytic coloring at 18-22°C using a 40-60Hz AC power supply, with an electrolytic voltage of 14-18V and a coloring time of 0.5-5min.

6. A colored film prepared by the bronze electrolytic coloring liquid for aluminum products according to any one of claims 1 to 3.

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