阅读说明：本技术 铜或铜合金板材的表面处理液及其制备方法和应用 (Surface treatment liquid for copper or copper alloy plate and preparation method and application thereof ) 是由 邓正平 田志斌 詹益腾 于 2020-11-19 设计创作，主要内容包括：本发明涉及铜或铜合金板材的表面处理液及其制备方法和应用。所述铜或铜合金板材的表面处理液,包含水以及在所述水中具有如下浓度的组分：铜盐4～12g/L、氧化剂6～18g/L、络合剂0.6～3g/L、加速剂0.2～0.8g/L,及表面活性剂0.1～0.5g/L；其中,所述氧化剂选自硝酸镍、硝酸、硝酸铜和二氧化硒中的两种；所述表面活性剂为2-乙基己基硫酸酯钠盐、直聚环氧基萘酚丙基磺酸钾盐或双酚A聚氧乙烯醚。该表面处理液能够满足大面积铜或铜合金板材连续发黑的要求,用于制作门板的板材发黑的连续生产时,生产效率高,同时,黑度好、色泽均匀,并与金属基体有良好的结合力。(The invention relates to a surface treatment fluid for copper or copper alloy plates, and a preparation method and application thereof. The surface treatment liquid for copper or copper alloy sheet material comprises water and components having the following concentrations in the water: 4-12 g/L of copper salt, 6-18 g/L of oxidant, 0.6-3 g/L of complexing agent, 0.2-0.8 g/L of accelerator and 0.1-0.5 g/L of surfactant; wherein the oxidant is selected from two of nickel nitrate, nitric acid, copper nitrate and selenium dioxide; the surfactant is 2-ethylhexyl sulfate sodium salt, straight epoxy naphthol propyl sulfonic acid potassium salt or bisphenol A polyoxyethylene ether. The surface treatment liquid can meet the requirement of continuous blackening of large-area copper or copper alloy plates, is used for continuous blackening production of plates for manufacturing door plates, and has the advantages of high production efficiency, good blackness, uniform color and good binding force with a metal matrix.)

1. A surface treatment liquid for a copper or copper alloy sheet, characterized by comprising water and components in the water at the following concentrations:

wherein the oxidant is selected from two of nickel nitrate, nitric acid, copper nitrate and selenium dioxide;

the surfactant is 2-ethylhexyl sulfate sodium salt, straight epoxy naphthol propyl sulfonic acid potassium salt or bisphenol A polyoxyethylene ether.

2. The surface treatment liquid for copper or copper alloy sheet according to claim 1, wherein the oxidizing agent is nitric acid and selenium dioxide.

3. The surface treatment liquid for copper or copper alloy sheet according to claim 1, wherein the surfactant is bisphenol a polyoxyethylene ether.

4. The surface treatment liquid for copper or copper alloy sheet according to claim 1, wherein the complexing agent is two selected from the group consisting of 2-aminopropionic acid, sodium tartrate, hydroxyethylidene diphosphonic acid, and sodium ethylenediaminetetramethylenephosphonate.

5. The surface treatment liquid for copper or copper alloy sheet according to claim 4, wherein the complexing agent is 2-aminopropionic acid and sodium ethylenediaminetetramethylenephosphonate.

6. The surface treatment liquid for copper or copper alloy sheet according to claim 1, wherein the accelerator is sodium chloride or nickel chloride.

7. The surface treatment liquid for copper or copper alloy sheet according to claim 1, wherein the copper salt is copper sulfate, copper methanesulfonate, or copper sulfamate.

8. The surface treatment liquid for copper or copper alloy sheet material according to any one of claims 1 to 7, wherein the pH is 1 to 2.

9. The method for producing the surface treatment liquid for copper or copper alloy sheet material as claimed in any one of claims 1 to 8, characterized by comprising the steps of:

dissolving the copper salt by using a proper amount of water to prepare a main salt solution;

adding an oxidant into the main salt solution, and dissolving; then the complexing agent, accelerator, surfactant and the remaining water are added.

10. Use of the surface treatment liquid for copper or copper alloy sheet material according to any one of claims 1 to 8 for blackening the surface of sheet material.

11. A method for blackening the surface of a plate is characterized by comprising the following steps:

a plate material immersed in the surface treatment liquid for a copper or copper alloy plate material according to any one of claims 1 to 8 at ordinary temperature to conduct blackening treatment.

12. A method of blackening a surface of a sheet material according to claim 11, wherein the time of the blackening treatment is 1min to 2 min.

Technical Field

The invention relates to the technical field of metal surface treatment, in particular to a surface treatment liquid for copper or copper alloy plates, and a preparation method and application thereof.

Background

With the improvement of living standard, people have higher and higher requirements for home decoration. The door is a door surface of a house, and many people select a black antique door to give people an elegant, antique and antique vision. The metal door plate is made of carbon steel, stainless steel, copper or copper alloy, but no matter which metal material is adopted, the antique appearance is made by the steps of carrying out blackening or no copper plating or direct blackening on the copper alloy in a chemical solution after the copper, the copper alloy, the carbon steel and the stainless steel are electroplated with the copper or the copper alloy, then carrying out wire drawing, spraying transparent paint for color fixation, cutting, assembling an outer frame, and manufacturing and forming.

The existing surface treatment liquid for blackening copper or copper alloy comprises sulfide, thiosulfate, copper ammonia complex system and the like. Some of these require warming and the reaction takes a long time to be slow, such as thiosulfate systems; some have unsatisfactory appearance and color and are not stable enough, such as sulfide systems; some of them have large smell in the reaction process and affect the environment and the health of operators, such as copper ammonia complex system. Meanwhile, the surface treatment liquid system for blackening copper or copper alloy cannot meet the requirement of continuously blackening large-area copper or copper alloy plates. Copper sulfate and selenium dioxide systems are adopted, but the defects of poor film layer binding force, insufficient blackness, uneven color and the like exist for continuous blackening of large-area copper or copper alloy plates.

Disclosure of Invention

In view of the above, it is necessary to provide a surface treatment liquid for copper or copper alloy sheet materials. The surface treatment liquid can meet the requirement of continuous blackening of large-area copper or copper alloy plates, is used for continuous blackening production of plates for manufacturing door plates, and has the advantages of high production efficiency, good blackness, uniform color and good binding force with a metal matrix.

The specific technical scheme is as follows:

a surface treatment fluid for copper or copper alloy sheet material, comprising water and the following components in concentration:

wherein the oxidant is selected from two of nickel nitrate, nitric acid, copper nitrate and selenium dioxide;

the surfactant is 2-ethylhexyl sulfate sodium salt, straight epoxy naphthol propyl sulfonic acid potassium salt or bisphenol A polyoxyethylene ether.

In one embodiment, the oxidizing agent is nitric acid and selenium dioxide.

In one embodiment, the surfactant is bisphenol a polyoxyethylene ether.

In one embodiment, the complexing agent is selected from two of 2-aminopropionic acid, sodium tartrate, hydroxyethylidene diphosphonic acid, and sodium ethylenediaminetetramethylenephosphonate.

In one embodiment, the complexing agent is 2-aminopropionic acid and sodium ethylenediaminetetramethylenephosphonate.

In one embodiment, the accelerator is sodium chloride or nickel chloride.

In one embodiment, the copper salt is copper sulfate, copper methylsulfonate or copper sulfamate.

In one embodiment, the pH of the surface treatment liquid for the copper or copper alloy sheet is 1-2.

The invention also provides a preparation method of the surface treatment liquid for the copper or copper alloy plate, which comprises the following steps:

dissolving the copper salt by using a proper amount of water to prepare a main salt solution;

adding an oxidant into the main salt solution, and dissolving; then the complexing agent, accelerator, surfactant and the remaining water are added.

The invention also provides application of the surface treatment liquid for the copper or copper alloy plate in blackening treatment of the surface of the plate.

The invention also provides a plate surface blackening method, which comprises the following steps:

and (3) soaking the plate in the surface treatment solution of the copper or copper alloy plate at normal temperature to perform blackening treatment.

In one embodiment, the blackening treatment is carried out for 1min to 2 min.

Compared with the prior art, the invention has the following beneficial effects:

according to the surface treatment liquid for the copper or copper alloy plate, copper salt, an oxidant, a complexing agent, an accelerator and a surfactant are combined according to a certain weight ratio, a specific kind of complexing agent is compounded in pairs, and the specific kind of surfactant is combined, so that copper salt metal ions and zinc ions dissolved in the alloy can be well complexed, the formed film is fine and uniform, the interfacial tension of metal and solution is reduced, and the binding force of the film layer and a metal substrate is increased, therefore, the blackening film which is uniform in color and luster, good in blackness and firm in binding is formed, the catalysis rate is high, the requirements of a large-area continuous blackening process for the copper or copper alloy plate can be met, the surface treatment liquid is suitable for continuous production of the blackening plate, and the production efficiency is improved.

In addition, the surface treatment liquid can be subjected to blackening treatment at normal temperature, the operation is simple, energy is saved, the wastewater treatment is easy, and only acid-base neutralization and precipitation treatment is needed, so that the environmental protection is facilitated.

Drawings

FIG. 1 is a real shot of a copper alloy sheet after being continuously subjected to a blackening treatment with the blackening solution of example 1;

FIG. 2 is a real shot of a copper alloy sheet after being continuously subjected to a blackening treatment with the blackening solution of example 4;

FIG. 3 is a real shot of a copper alloy sheet after being continuously subjected to a blackening treatment with the blackening solution of comparative example 1;

FIG. 4 is a real shot of a copper alloy sheet after being subjected to continuous blackening treatment with the blackening solution of comparative example 2;

fig. 5 is a real shot of a copper alloy sheet material after being continuously subjected to a blackening treatment with the blackening solution of comparative example 3.

Detailed Description

The surface treatment liquid for copper or copper alloy sheet material of the present invention, its preparation method and use will be described in further detail below with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The continuous blackening process is characterized in that a plate to be blackened continuously passes through the surface treatment liquid in a roll-to-roll mode under mechanical transmission. The process is a full-automatic production process of the blackened plate, and generally speaking, the time for the plate to be blackened to be in the surface treatment liquid is about 1 min-2 min.

The invention provides a surface treatment liquid for copper or copper alloy plates, which comprises water and components with the following concentrations in the water:

wherein, the oxidant is selected from two of nickel nitrate, nitric acid, cupric nitrate and selenium dioxide;

the surfactant is 2-ethylhexyl sulfate sodium salt, straight epoxy naphthol propyl sulfonic acid potassium salt or bisphenol A polyoxyethylene ether.

In one example, the pH of the surface treatment liquid for copper or copper alloy sheet material is 1 to 2.

In one example, the surface treatment liquid for copper or copper alloy sheet material contains water and components in the water having the following concentrations:

preferably, the oxidizing agent is nitric acid and selenium dioxide. The two oxidants are compounded, so that a synergistic effect can be well played, nitric acid can be used for maintaining the pH value of the solution within the range of 1-2, activating corrosion is carried out on the metal surface, and meanwhile, the selenium dioxide is cooperated to oxidize copper ions into black CuSe and oxidize zinc ions dissolved in the copper alloy into black ZnSe. More preferably, the weight ratio of the oxidant is 1.5-3: 1, wherein the nitric acid refers to a nitric acid aqueous solution with the volume fraction of 65-75%.

Preferably, the surfactant is bisphenol a polyoxyethylene ether. The adoption of a proper surfactant can reduce the interfacial tension of the solution and the metal, and simultaneously, small foams are generated in the stirring process and are not easy to be adsorbed on the surface of the metal or the film layer, so that the surface of the metal is lubricated, the blackening film is uniform and consistent, and the phenomena of the blackening film layer such as floating and ash floating are eliminated.

In one example, the complexing agent is selected from two of 2-aminopropionic acid, sodium tartrate, hydroxyethylidene diphosphonic acid, and sodium ethylenediaminetetramethylenephosphonate. The complexing agent is further compounded in pairs, the reaction speed is controlled by complexing copper ions in the solution, and meanwhile, the interfacial tension of metal and the solution is reduced by the synergistic effect of the surfactant, so that the formed film is fine, and the binding force with a substrate is further increased. Preferably, the complexing agent is 2-aminopropionic acid and sodium ethylenediaminetetramethylenephosphonate. More preferably, the complexing agent is 2-aminopropionic acid and sodium ethylene diamine tetramethylenephosphonate in a weight ratio of 1: 1.5-5.

In one example, the accelerator is sodium chloride or nickel chloride. The accelerator can play a role in catalyzing blackening reaction and improve the film forming reaction speed. Preferably, the accelerator is nickel chloride.

In one example, the copper salt is copper sulfate, copper methylsulfonate, or copper sulfamate. Preferably, the copper salt is copper methanesulfonate.

In one example, the surface treatment liquid for copper or copper alloy sheet material described above contains water and components having the following concentrations in the water:

"70% nitric acid" refers to a volume fraction of 70% aqueous nitric acid.

In one example, the solution is based on water as a main solvent, and comprises the following components in terms of each liter of the solution:

the invention also provides a preparation method of the surface treatment liquid for the copper or copper alloy plate, which comprises the following steps:

dissolving the copper salt by using a proper amount of water to prepare a main salt solution;

adding an oxidant into the main salt solution, and dissolving; then the complexing agent, accelerator, surfactant and the remaining water are added.

In one example, a method for preparing a surface treatment liquid for a copper or copper alloy sheet material includes the steps of:

completely dissolving the copper methanesulfonate in half of the required water;

slowly adding nitric acid and selenium dioxide into the solution in sequence, and stirring to completely dissolve the nitric acid and the selenium dioxide;

adding 2-aminopropionic acid, ethylene diamine tetramethylene phosphonic acid sodium salt and nickel chloride into the solution;

adding a surfactant bisphenol A polyoxyethylene ether into the solution;

adding another half water, and stirring uniformly.

The invention also provides application of the surface treatment liquid for the copper or copper alloy plate in blackening treatment of the surface of the plate.

The invention also provides a plate surface blackening method, which comprises the following steps:

the plate material is immersed in the surface treatment liquid for copper or copper alloy plate material as described above at normal temperature to carry out blackening treatment.

In one example, the blackening treatment is performed for 1 to 2 min.

The following specific examples are provided, and the raw materials used in the examples are all commercially available unless otherwise specified.

Example 1

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

the preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

4g of copper methanesulfonate and 4g of 70% nitric acid were dissolved in 500mL of water in sequence;

slowly adding 2g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 0.1g of 2-aminopropionic acid, 0.5g of ethylenediamine tetramethylene sodium phosphonate and 0.2g of nickel chloride into the solution;

adding 0.1g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Example 2

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	12g
70% nitric acid	12g
		Selenium dioxide	6g
2-aminopropionic acid	1g
		Ethylenediaminetetramethylenephosphonic acid sodium salt	2g
Nickel chloride	0.8g
		Bisphenol A polyoxyethylene ether	0.5g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 12g of copper methanesulfonate and 12g of 70% nitric acid in 500mL of water in sequence;

slowly adding 6g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 1g of 2-aminopropionic acid, 2g of ethylenediamine tetramethylene sodium phosphonate and 0.8g of nickel chloride into the solution;

adding 0.5g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Example 3

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	8g
70% nitric acid	8g
		Selenium dioxide	4g
2-aminopropionic acid	0.65g
		Ethylenediaminetetramethylenephosphonic acid sodium salt	1.25g
Nickel chloride	0.5g
		Bisphenol A polyoxyethylene ether	0.3g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 0.65g of 2-aminopropionic acid, 1.25g of ethylenediamine tetramethylene sodium phosphonate and 0.5g of nickel chloride into the solution;

adding 0.3g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Example 4

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	8g
70% nitric acid	8g
		Selenium dioxide	4g
2-aminopropionic acid	0.65g
		Tartaric acid sodium salt	1.25g
Nickel chloride	0.5g
		Bisphenol A polyoxyethylene ether	0.3g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 2-aminopropionic acid 0.65g, sodium tartrate 1.25g and nickel chloride 0.5g into the solution;

adding 0.3g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Example 5

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

the preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 0.65g of 2-aminopropionic acid, 1.25g of ethylenediamine tetramethylene sodium phosphonate and 0.5g of nickel chloride into the solution;

adding 0.3g of surfactant straight epoxy naphthol propyl sulfonic acid potassium salt into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Comparative example 1

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	8g
70% nitric acid	8g
		Sodium persulfate	4g
2-aminopropionic acid	0.65g
		Ethylenediaminetetramethylenephosphonic acid sodium salt	1.25g
Nickel chloride	0.5g
		Bisphenol A polyoxyethylene ether	0.3g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of sodium persulfate into the solution, and stirring to completely dissolve the sodium persulfate;

adding 0.65g of 2-aminopropionic acid, 1.25g of ethylenediamine tetramethylene sodium phosphonate and 0.5g of nickel chloride into the solution;

adding 0.3g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Comparative example 2

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	8g
70% nitric acid	8g
		Selenium dioxide	4g
2-aminopropionic acid	0.65g
		Ethylenediaminetetramethylenephosphonic acid sodium salt	1.25g
Nickel chloride	0.5g
		Octyl phenol polyoxyethylene ether TX-10	0.3g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 2-aminopropionic acid 0.65g, sodium ethylenediamine tetramethylene phosphonate 1.25g and nickel chloride 0.5g into the solution;

adding 0.3g of surfactant octyl phenol polyoxyethylene ether TX-10 into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

Comparative example 3

The embodiment is a normal-temperature continuous blackening solution applied to the surface of a copper or copper alloy plate, and the solution adopts the following raw materials:

composition of plating solution	Dosage of
		Copper methylsulfonate	8g
70% nitric acid	8g
		Selenium dioxide	4g
2-aminopropionic acid	0.65g
		Ethylenediaminetetramethylenephosphonic acid sodium salt	1.25g
Bisphenol A polyoxyethylene ether	0.3g

The preparation method of the normal-temperature continuous blackening solution applied to the surface of the copper or copper alloy plate comprises the following steps:

completely dissolving 8g of copper methanesulfonate and 8g of 70% nitric acid in 500mL of water in sequence;

slowly adding 4g of selenium dioxide into the solution, and stirring to completely dissolve the selenium dioxide;

adding 0.65g of 2-aminopropionic acid and 1.25g of ethylenediamine tetramethylene phosphonic acid sodium into the solution;

adding 0.3g of surfactant bisphenol A polyoxyethylene ether into the solution, and uniformly stirring;

adding pure water to a constant volume of 1 liter.

The blackening effect of the normal temperature continuous blackening solution on the surface of the copper or copper alloy sheet prepared in the above examples and comparative examples was tested.

1. The test method comprises the following steps: taking the same batch of copper alloy plates, and respectively carrying out the normal-temperature continuous blackening process on the surfaces of the copper alloy plates by adopting the blackening solutions of the examples 1-5 and the comparative examples 1-3. The process flow is as follows: winding, mechanical wire drawing, blackening, washing, drying, mechanical wire drawing, spraying transparent paint for color fixation, drying, inspecting and winding.

The blackening operating conditions were as follows:

the temperature is 25 DEG C

The pH value is 1.0-2.0;

and (3) carrying out blackening treatment on the copper alloy plate by adopting a continuous blackening process, wherein in the blackening treatment process, the blackening solution is circularly filtered by a filter, 5 times per hour, the copper alloy plate uniformly moves in the blackening solution at a moving speed of 2 m/min, and the time for the copper alloy plate to be in the surface treatment solution is about 1.5 min.

2. And (3) testing results:

and (4) judging the standard: after blackening, drying and wire drawing, the film has good blackness, is continuous and uniform, does not fall off, and is qualified if no hair is generated.

The test results are specifically shown in the following table 1 and fig. 1 to 5:

TABLE 1

The copper alloy sheet prepared by continuous blackening of the blackening solution in the embodiment 1 is shown in figure 1, and the film has good blackness, is continuous and uniform, does not fall off and does not generate flowers. The copper alloy sheets obtained in examples 2 and 3 were similar to those in example 1. The copper alloy sheet obtained after the continuous blackening with the blackening solution of example 4 is shown in FIG. 2, and has a slight unevenness in comparison with example 1. The copper alloy sheet obtained in example 5 was similar to that obtained in example 4.

The copper alloy plate prepared by continuously blackening the blackening solution of the comparative example 1 is shown in figure 3, and the blackness of the film layer is insufficient, and the film layer is colored and uneven. The copper alloy sheet obtained after the continuous blackening with the blackening solution of comparative example 2 is shown in FIG. 4, and the film layer is streaky and uneven. The copper alloy sheet obtained after the continuous blackening of the blackening solution of comparative example 3 is shown in FIG. 5, and the film layer is not black, and is colored and uneven.

The results show that the blackening film layer prepared by the normal-temperature continuous blackening solution for the surface of the copper or copper alloy plate compounded by the invention has excellent performance and completely meets various requirements for manufacturing the door plate after blackening.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.