Environment-friendly chromium-free passivator and preparation method thereof

Abstract

The invention relates to the technical field of metal surface anti-oxidation treatment, in particular to an environment-friendly chromium-free passivator and a preparation method thereof. The environment-friendly chromium-free passivating agent provided by the invention comprises the following components in percentage by weight: 5.0%-10.0% of sodium phytate; 1.0%-5.0% of tannic acid; 2.0%-5.0% of zinc sulfate; 1.0%-3.0% of glucose; 2.0%-6.0% of a silane coupling agent; 0.1% to 1.5% of a thickening agent; 1%-3% of a pH regulator; the sum of all the components is 100%. The passivator provided by the invention has good adhesive force on the metal surface, can form a compact passive film, has good corrosion resistance, does not contain harmful heavy metals such as chromium and the like, is wide in raw material source and relatively low in price, is few in process steps of the preparation method, does not need complex equipment, is mild in reaction condition, is beneficial to reducing the production cost, and is suitable for industrial production. The method is suitable for large-scale industrial popularization and application.

Description

Technical Field

[0001] This invention relates to the field of metal surface anti-oxidation treatment technology, and in particular to an environmentally friendly chromium-free passivating agent and its preparation method. Background Technology

[0002] Metal surface passivation is a key process for improving the corrosion resistance of metallic materials and is widely used in construction, transportation, machinery, electronics, aerospace, and other fields. Passivation treatment forms a dense protective film on the metal surface, effectively blocking contact between the metal and corrosive media, thereby slowing down the corrosion process. Traditional passivation technology mainly relies on chromate systems, including hexavalent chromium and trivalent chromium passivation solutions, which have long dominated industrial applications due to their excellent film-forming properties and corrosion resistance.

[0003] While hexavalent chromium passivation can create a passivation film with rich colors and excellent corrosion resistance, it is highly toxic and has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Hexavalent chromium is readily soluble in water and can enter the human body through skin contact and inhalation, causing serious damage to the liver, kidneys, respiratory system, and reproductive system. The EU RoHS Directive (2011 / 65 / EU) explicitly prohibits the use of hexavalent chromium passivated components in electrical and electronic equipment. The US Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) have also established strict standards for the use and emission of hexavalent chromium.

[0004] As a transitional solution, trivalent chromium passivation technology reduces the toxicity of chromium to some extent, as its toxicity is only about 1% that of hexavalent chromium and it is not easily absorbed through the skin. However, trivalent chromium passivation still has two main problems: first, the passivation film may oxidize and transform into hexavalent chromium under long-term use or specific environmental conditions; second, the trivalent chromium passivation solution has poor stability and is prone to precipitation, affecting process stability and passivation effect. Therefore, many countries and regions, including the European Union, have begun to restrict the application of trivalent chromium passivation technology.

[0005] In the research of chromium-free passivation technology, various alternative systems have been explored. Molybdate systems were one of the earliest chromium substitutes studied, as molybdenum and chromium belong to the same Group VIB elements and have similar chemical properties. Molybdate passivation solutions can form passivation films of various colors such as yellow, blue, and purple, but their corrosion resistance is significantly lower than that of chromate passivation films, and molybdenum itself poses certain environmental risks and is costly. Titanium salt and zirconium salt systems form a protective film on the surface through the hydrolysis and polymerization of metal ions, exhibiting good corrosion resistance, but suffer from problems such as a narrow processing window, difficulty in process control, and high cost. Rare earth metal (such as cerium and lanthanum) passivation systems can form passivation films with excellent corrosion resistance, but the film formation rate is extremely slow, typically requiring 24-48 hours to reach performance requirements, far from meeting the efficiency demands of industrial production.

[0006] Silicate systems are low-cost and environmentally friendly, but the passivation films they form are often uneven and have unstable corrosion resistance, especially prone to failure in humid and hot environments. Organic acid systems (such as phytic acid, tannic acid, and citric acid) form a protective layer on the metal surface through carboxyl and hydroxyl groups, offering good environmental performance, but their film performance is insufficient when used alone. In recent years, composite passivation systems have become a research hotspot, utilizing the synergistic effect of combining different components to improve passivation film performance. For example, combining phytic acid with silane coupling agents and nanomaterials can significantly improve the density and adhesion of the passivation film. Summary of the Invention

[0007] In view of the shortcomings of existing chromium-free passivating agents, such as insufficient corrosion resistance, poor adhesion, complex processes, or high costs, this invention aims to develop an environmentally friendly chromium-free passivating agent. This passivating agent contains no chromium, is environmentally friendly, and can form a passivation film with excellent corrosion resistance and good adhesion on metal surfaces. Furthermore, this invention provides a method for preparing this passivating agent, which is simple, easy to control, and low in cost, making it suitable for industrial production.

[0008] The first aspect of this invention provides an environmentally friendly chromium-free passivating agent, comprising the following components by weight percentage:

[0009] Sodium phytate 5.0%–10.0%;

[0010] Tannic acid 1.0%–5.0%;

[0011] Zinc sulfate 2.0%–5.0%;

[0012] Glucose 1.0%–3.0%;

[0013] Silane coupling agent 2.0%–6.0%;

[0014] Thickener 0.1%–1.5%;

[0015] pH adjuster 1%–3%;

[0016] The remaining amount of deionized water is used to make the total of all components 100%.

[0017] A second aspect of this invention provides a method for preparing the above-mentioned environmentally friendly chromium-free passivating agent, comprising the following steps:

[0018] (1) Add some deionized water to the reaction vessel, turn on the stirring, and add sodium phytate, tannic acid and glucose in sequence, stirring until completely dissolved;

[0019] (2) Add zinc sulfate slowly while stirring, continue stirring to allow the reaction to proceed, then add silane coupling agent and continue stirring until completely dissolved;

[0020] (3) Slowly add the thickener dispersion while stirring. After adding, continue stirring to ensure uniform dispersion.

[0021] (4) Slowly add pH adjuster to adjust the pH of the system, add the remaining deionized water, stir to mix evenly, filter, and the product is obtained.

[0022] A third aspect of the present invention provides a metal surface passivation process, comprising the following steps:

[0023] (1) Pretreatment: The metal surface is pickled and washed with water to obtain pretreated copper foil;

[0024] (2) Passivation treatment: The pretreated metal is immersed in the above-mentioned environmentally friendly chromium-free passivating agent, or the above-mentioned environmentally friendly chromium-free passivating agent is sprayed onto the surface of the pretreated metal to form a dense passivation film on the metal surface.

[0025] (3) Post-treatment: Remove the residual environmentally friendly chromium-free passivating agent from the metal surface and dry it.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The passivating agent provided by this invention does not contain heavy metal ions such as chromium and nickel, fully complies with environmental protection requirements, will not cause pollution to the environment during production and use, and is harmless to the health of operators.

[0028] 2. The passivating agent provided by this invention, which is the main film-forming agent (sodium phytate) and the auxiliary film-forming agent (tannic acid, zinc sulfate), works synergistically to form a dense and uniform composite passivation film on the metal surface. This film can effectively block the contact between water, oxygen and other corrosive media and the metal substrate, and significantly improve the corrosion resistance of the metal material.

[0029] 3. The passivation film formed by the passivating agent provided by the present invention is firmly bonded to the metal substrate. At the same time, the silane coupling agent added by the present invention improves the surface properties of the film layer, and the thickener increases the contact time between the passivating agent and the metal surface, so that the active components in the passivating agent have more opportunities to react chemically with the metal surface, resulting in good adhesion of the subsequent coating and meeting the needs of practical applications.

[0030] 4. The raw materials used in the passivating agent of this invention are all common chemical raw materials, which are widely available and relatively inexpensive. The preparation method has few process steps, and the components can be dissolved and mixed at room temperature or low temperature. No complicated equipment is required. The reaction conditions are mild, easy to control, have good repeatability, and low energy consumption, which helps to reduce production costs and is suitable for large-scale industrial application. Detailed Implementation

[0031] The following specific embodiments further illustrate the present invention, which describes an environmentally friendly chromium-free passivating agent and its preparation method.

[0032] This invention provides a highly efficient and environmentally friendly chromium-free passivating agent formulation. The formulation uses sodium phytate as the main film-forming substance, combined with various organic acids, metal salts and auxiliary additives. Through the synergistic effect of the components, a dense, uniform protective film with self-healing function is formed on the metal surface.

[0033] The first aspect of this invention provides an environmentally friendly chromium-free passivating agent, comprising the following components by weight percentage:

[0034] Sodium phytate 5.0%–10.0%;

[0035] Tannic acid 1.0%–5.0%;

[0036] Zinc sulfate 2.0%–5.0%;

[0037] Glucose 1.0%–3.0%;

[0038] Silane coupling agent 2.0%–6.0%;

[0039] Thickener 0.1%–1.5%;

[0040] pH adjuster 1%–3%;

[0041] The remaining amount of deionized water is used to make the total of all components 100%.

[0042] In the environmentally friendly chromium-free passivating agent formulation of the present invention, by optimizing the selection and ratio of components, the use of toxic substances is avoided while ensuring excellent corrosion resistance. Each component has a clear functional positioning and achieves excellent passivation effect through synergistic effect.

[0043] Sodium phytate, as the main film-forming substance, contains six phosphate groups in its molecular structure, enabling it to form stable chelates with metal surfaces. Simultaneously, these phosphate groups can cross-link to form a three-dimensional network structure, enhancing the density and chemical stability of the passivation film. Compared to free phytic acid, sodium phytate exhibits better water solubility and storage stability, preventing excessive corrosion of the metal substrate by phytic acid at low pH values.

[0044] Tannic acid, as an organic acid component, has multiple functions: It contains multiple phenolic hydroxyl groups (-OH) and carboxyl groups (-COOH), which can chemically react with metal surfaces to help sodium phytate form a more complete protective film. This protective film effectively prevents the metal from contacting the external environment (such as oxygen, water, and corrosive media), thus playing a role in corrosion prevention. On the other hand, it can adjust the pH value of the solution (the optimal pH range is 3.5-6.5), enhancing the adhesion between the passivation film and the metal surface and preventing the passivation film from peeling off or wearing away during use. Tannic acid also has good antioxidant properties, inhibiting oxidation reactions on metal surfaces.

[0045] Zinc sulfate provides zinc ions (Zn) in zinc sulfate. 2+ Zinc ions can undergo complexation reactions with other components in the passivation solution (such as tannic acid and sodium phytate) to form stable complexes. These complexes can fill the micropores and defects in the passivation film, enhancing its density and corrosion resistance. Zinc ions possess a certain self-healing ability within the passivation film. When the passivation film is locally damaged, zinc ions can react with oxygen and water in the surrounding environment to reform zinc oxide or hydroxide, thereby repairing the damaged passivation film. Zinc ions can form conductive channels within the passivation film, improving its conductivity and ensuring that it maintains good electrical performance while providing corrosion protection. Compared to nickel sulfate, zinc sulfate is cheaper and more environmentally friendly.

[0046] Glucose, as a reducing agent and complexing agent, can effectively inhibit oxidation reactions on metal surfaces, promote uniform film formation, and impart a certain degree of flexibility to the passivation film, reducing the tendency to crack. The hydroxyl groups of glucose can also form hydrogen bonds with the metal surface, enhancing film adhesion.

[0047] Silane coupling agents, acting as surfactants and wetting agents, can reduce the surface tension of passivation solutions, improving their spreadability and penetration on metal surfaces. They can also form cross-linked network structures, enhancing the mechanical strength and toughness of the passivation film. Simultaneously, the silicon-oxygen-silicon bonds formed by silane coupling agents possess excellent weather resistance and chemical resistance, effectively resisting environmental corrosion such as ultraviolet light, water, acids, and alkalis. This allows the passivation film to maintain good protective performance even in harsh environments.

[0048] Thickeners are used to adjust the viscosity of the passivation solution, making it easier to spread evenly on the metal surface. In synergy with sodium phytate, tannic acid, and zinc sulfate, they help form a uniform passivation film, ensuring consistent coverage of the metal surface and preventing excessively thick localized film formation, thereby improving corrosion resistance. Thickeners can increase the contact time between the passivation solution and the metal surface, giving the active components in the passivation solution more opportunities to react chemically with the metal surface, thus enhancing the adhesion of the passivation film, especially suitable for spray or roll coating processes.

[0049] pH adjusters are mainly used to adjust the pH of the passivation solution to ensure that the pH value of the passivation solution is maintained within a suitable range (3.5-6.5), thereby ensuring the smooth progress of the passivation reaction and the performance of the passivation film.

[0050] Preferably, the weight percentage of sodium phytate in the chromium-free passivating agent is 6.0% to 8.0%, which can be 6.0% to 7.0% or 7.0% to 8.0%.

[0051] Preferably, the tannic acid in the chromium-free passivating agent has a weight percentage of 2.0% to 3.0%, which can be 2.0% to 2.5% or 2.5% to 3.0%.

[0052] Preferably, the zinc sulfate content in the chromium-free passivating agent is 3.0% to 4.5% by weight, which can be 3.0% to 3.5%, 3.5% to 4.0%, or 4.0% to 4.5%.

[0053] Preferably, the weight percentage of glucose in the chromium-free passivating agent is 1.5% to 2.5%, which can be 1.5% to 2.0% or 2.0% to 2.5%.

[0054] Preferably, the weight percentage of the silane coupling agent in the chromium-free passivating agent is 3.0% to 5.0%, which can be 3.0% to 3.5%, 3.5% to 4.0%, 4.0% to 4.5%, or 4.5% to 5.0%.

[0055] Preferably, the thickener in the chromium-free passivating agent has a weight percentage of 0.3% to 1.0%, which can be 0.3% to 0.5%, 0.5% to 0.7%, or 0.7% to 1.0%.

[0056] The weight percentage of pH adjuster in the chromium-free passivating agent described in this invention is adjusted according to the pH adjustment requirements.

[0057] Preferably, the silane coupling agent is selected from any one or a combination of two of KH550 and KH560, and can be KH550 or KH560, or a combination of KH550 and KH560 in any ratio.

[0058] Preferably, the thickener is selected from any one or a combination of sodium carboxymethyl cellulose, xanthan gum, and polyvinyl alcohol. It can be sodium carboxymethyl cellulose, xanthan gum, and polyvinyl alcohol; it can also be a combination of sodium carboxymethyl cellulose and xanthan gum, a combination of sodium carboxymethyl cellulose and polyvinyl alcohol, a combination of xanthan gum and polyvinyl alcohol, or a combination of all three. The molecular weight of the polyvinyl alcohol is typically between 50,000 and 120,000 Da, ensuring both thickening effect and preventing the encapsulation of metal ions.

[0059] Preferably, the pH adjuster is selected from phytic acid, which, compared with traditional acids and bases, has a wider effective buffer zone and can react with Zn. 2+ Synergistic film formation improves film density, enhances salt spray resistance, and makes the film biodegradable and more environmentally friendly.

[0060] Preferably, the pH of the environmentally friendly chromium-free passivating agent is 3.5 to 6.5, which can be 3.5 to 4.0, 4.0 to 4.5, 4.5 to 5.0, 5.0 to 5.5, 5.5 to 6.0, or 6.0 to 6.5, and more preferably 4.0 to 5.5.

[0061] A second aspect of this invention provides a method for preparing the above-mentioned environmentally friendly chromium-free passivating agent, comprising the following steps:

[0062] (1) Add some deionized water to the reaction vessel, turn on the stirring, and add sodium phytate, tannic acid and glucose in sequence, stirring until completely dissolved;

[0063] (2) Add zinc sulfate slowly while stirring, continue stirring to allow the reaction to proceed, then add silane coupling agent and continue stirring until completely dissolved;

[0064] (3) Slowly add the thickener dispersion while stirring. After adding, continue stirring to ensure uniform dispersion.

[0065] (4) Slowly add pH adjuster to adjust the pH of the system, add the remaining deionized water, stir to mix evenly, filter, and the product is obtained.

[0066] In some embodiments of the present invention, in step (1), the weight of the deionized water accounts for 50% to 60% of the total weight of the deionized water, which can be 50% to 55% or 55% to 60%. Specifically, the deionized water is added in three steps: the first step is the deionized water in step (1), the second step is the deionized water in the thickener dispersion, and the third step is the remaining deionized water in step (4).

[0067] In some embodiments of the present invention, in step (1), the stirring rate is 100-200 rpm, or it can be 100-130 rpm, 130-150 rpm, 150-180 rpm, or 180-200 rpm.

[0068] In some embodiments of the present invention, in step (1), the stirring time is 10-15 min, which can be 10-12 min, 12-14 min, or 14-15 min. After sodium phytate, tannic acid, and glucose are completely dissolved, the solution can be observed to be clear and transparent.

[0069] In some embodiments of the present invention, in step (2), the continuous stirring time is 20-30 min, which can be 20-22 min, 22-24 min, 24-26 min, 26-28 min, or 28-30 min. By controlling the addition rate of zinc sulfate and stirring, local supersaturation is avoided. After the zinc sulfate is completely added, continuous stirring is carried out to ensure that zinc ions are fully complexed.

[0070] In some embodiments of the present invention, in step (3), the preparation method of the thickener dispersion includes adding the thickener to warm water at 40-50°C and dispersing it evenly. The temperature can be 40-42°C, 42-44°C, 44-46°C, 46-48°C, or 48-50°C. In some specific embodiments of the present invention, the weight of the warm water accounts for 1% to 10% of the total weight of deionized water. The thickener dispersion is a uniform colloidal solution; the purpose of slowly adding it while stirring is to avoid clumping. After complete addition, the solution reaches a uniform and transparent state.

[0071] In some embodiments of the present invention, in step (3), the stirring rate is 150-300 rpm, which can be 150-180 rpm, 180-200 rpm, 200-220 rpm, 220-250 rpm, 250-280 rpm, or 280-300 rpm.

[0072] In some embodiments of the present invention, in step (3), the time for continuing stirring is 30 to 60 minutes, which can be 30 to 35 minutes, 35 to 40 minutes, 40 to 45 minutes, 45 to 50 minutes, 50 to 55 minutes, or 55 to 60 minutes.

[0073] In some embodiments of the present invention, in step (4), the pH of the system is tested while the pH adjuster is added; specifically, the pH of the system is tested first, and then the pH adjuster is added. After each addition of the pH adjuster, the mixture is stirred evenly, and then the pH of the system is tested again.

[0074] In some embodiments of the present invention, in step (4), the pH of the system is 3.5 to 6.5, which can be 3.5 to 4.0, 4.0 to 4.5, 4.5 to 5.0, 5.0 to 5.5, 5.5 to 6.0, or 6.0 to 6.5, and more preferably 4.0 to 5.5.

[0075] In some embodiments of the present invention, in step (4), the stirring time is 5 to 10 minutes, which can be 5 to 6 minutes, 6 to 7 minutes, 7 to 8 minutes, 8 to 9 minutes, or 9 to 10 minutes.

[0076] In some embodiments of the present invention, in step (5), the filtering device is a filter screen, which removes impurity particles that may be present in the passivating agent by filtration. Preferably, the filter screen is made of stainless steel, PP or PTFE, and the pore size of the filter screen is selected according to process requirements, for example, 1 to 50 μm.

[0077] A third aspect of the present invention provides a metal surface passivation process, comprising the following steps:

[0078] (1) Pretreatment: The metal surface is pickled and washed with water to obtain pretreated copper foil;

[0079] (2) Passivation treatment: The pretreated metal is immersed in the above-mentioned environmentally friendly chromium-free passivating agent, or the above-mentioned environmentally friendly chromium-free passivating agent is sprayed onto the surface of the pretreated metal to form a dense passivation film on the metal surface.

[0080] (3) Post-treatment: Remove the residual environmentally friendly chromium-free passivating agent from the metal surface and dry it.

[0081] The environmentally friendly chromium-free passivating agent of this invention is suitable for copper foils and copper products of various specifications. The passivation film formed is colorless and does not affect the conductivity and appearance of the current collector.

[0082] In some embodiments of the present invention, in step (1), the metal is selected from copper foil with a thickness of 6 to 10 μm, which can be 6 to 8 μm or 8 to 10 μm.

[0083] In some embodiments of the present invention, in step (1), the washing medium used for pickling is a sulfuric acid solution with a concentration of 5wt% to 10wt%, which can be 5wt% to 6wt%, 6wt% to 7wt%, 7wt% to 8wt%, 8wt% to 9wt%, or 9wt% to 10wt%. The pickling time is 1 to 2 minutes, which can be 1 to 1.5 minutes or 1.5 to 2 minutes. The purpose of pickling is to remove impurities such as oxides and oil stains from the surface, so as to form a rough microstructure on the surface of the copper foil and increase the adhesion of the subsequent passivation film. The purpose of water rinsing is to remove acid from the metal surface, ensure that there is not much acid residue on the metal surface, and avoid causing changes in the pH of the passivation solution.

[0084] In some embodiments of the present invention, in step (2), the temperature of the environmentally friendly chromium-free passivating agent is room temperature, which refers to the temperature range that the passivating liquid naturally maintains under conditions of no external heating or cooling, typically 20 to 30°C.

[0085] In some embodiments of the present invention, in step (2), an electric current is applied while the device is immersed in an environmentally friendly chromium-free passivating agent, with a current density of 0.5–2 A / dm². 2 It can be 0.5~1A / dm 2 1~1.5A / dm 2 It can also be 1.5~2A / dm 2The treatment time is 5-10 seconds, which can be 5-7 seconds, 7-8 seconds, or 8-10 seconds; or it can be immersed in an environmentally friendly chromium-free passivating agent without applying current, and the treatment time is 10-20 minutes, which can be 10-12 minutes, 12-14 minutes, 14-16 minutes, 16-18 minutes, or 18-20 minutes.

[0086] In some embodiments of the present invention, in step (2), the spraying pressure is 0.1-0.3 MPa, which can be 0.1-0.15 MPa, 0.15-0.2 MPa, 0.2-0.25 MPa, or 0.25-0.3 MPa, and the time is 20-30 s, which can be 20-22 s, 22-24 s, 24-26 s, 26-28 s, or 28-30 s.

[0087] In some embodiments of the present invention, in step (3), the method of removing the residual environmentally friendly chromium-free passivating agent on the surface of the copper foil is to use a rubber roller to press it.

[0088] In some embodiments of the present invention, in step (3), the drying is hot air drying, the temperature is 60-80°C, which can be 60-65°C, 65-70°C, 70-75°C, or 75-80°C, and the time is 30-60s, which can be 30-35s, 35-40s, 40-45s, 45-50s, 50-55s, or 55-60s.

[0089] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention.

[0090] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, this invention can be implemented using any prior art methods, apparatus, and materials similar to or equivalent to those described in the embodiments of this invention, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention.

[0091] Unless otherwise stated, the experimental methods, detection methods, and preparation methods disclosed in this invention all employ conventional techniques in analytical chemistry and related fields. Unless otherwise stated, all materials and equipment used in this invention are commercially available.

[0092] Example 1

[0093] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0094] Sodium phytate 6.0%;

[0095] Tannic acid 2.0%;

[0096] Zinc sulfate 3.0%;

[0097] 1.5% glucose;

[0098] Silane coupling agent (KH550) 3.0%;

[0099] Thickener (sodium carboxymethyl cellulose) 0.3%;

[0100] pH adjuster (phytic acid) 1.5%;

[0101] The remaining amount of deionized water is used to make the total of all components 100%.

[0102] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0103] (1) Take each component raw material according to weight percentage;

[0104] (2) Add 120 mL of deionized water to a 250 mL beaker, start the stirring device (150 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 12 min until completely dissolved.

[0105] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 25 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0106] (4) After pre-dispersing the thickener into a colloidal solution in 40°C warm water, slowly add it to the solution obtained in step (3) and stir for 180 minutes until it is uniform and transparent.

[0107] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 4.0, add deionized water to 250mL, stir for 8min, filter to remove impurity particles, and the product is obtained.

[0108] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0109] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 8wt% sulfuric acid solution for 1min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0110] (2) Passivation treatment: The pretreated copper foil is completely immersed in an environmentally friendly chromium-free passivating agent, and a passivation current is applied with a current density of 1A / dm².2 The passivation solution temperature was room temperature (25℃), the passivation solution circulation flow rate was 50L / min, and the treatment time was 8s;

[0111] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 65°C for 48 seconds.

[0112] The passivation film in this embodiment is uniform and has good adhesion, indicating that the thickener can still effectively improve the workability of the solution and reduce dripping even at low concentrations.

[0113] Example 2

[0114] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0115] Sodium phytate 7.0%;

[0116] Tannic acid 2.5%;

[0117] Zinc sulfate 3.5%;

[0118] Glucose 2.0%;

[0119] Silane coupling agent (KH550) 4.0%;

[0120] Thickener (sodium carboxymethyl cellulose) 1.0%;

[0121] pH adjuster (phytic acid) 2.0%;

[0122] The remaining amount of deionized water is used to make the total of all components 100%.

[0123] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0124] (1) Take each component raw material according to weight percentage;

[0125] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 14 min until completely dissolved.

[0126] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 30 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0127] (4) After pre-dispersing the thickener into a colloidal solution in 45°C warm water, slowly add it to the solution obtained in step (3) and stir for 210 minutes until it is uniform and transparent.

[0128] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.0, add deionized water to 250mL, stir for 10min, filter to remove impurity particles, and the product is obtained.

[0129] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0130] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0131] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.2 MPa for 25 seconds;

[0132] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0133] The passivation film in this embodiment has excellent adhesion, indicating that a high concentration of thickener significantly improves the stability of the solution, reduces splashing during spraying, and results in better film formation.

[0134] Example 3

[0135] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0136] Sodium phytate 8.0%;

[0137] Tannic acid 3.0%;

[0138] Zinc sulfate 4.0%;

[0139] Glucose 2.5%;

[0140] 5.0% silane coupling agent (KH560);

[0141] Thickener (sodium carboxymethyl cellulose) 0.5%;

[0142] pH adjuster (phytic acid) 1.0%;

[0143] The remaining amount of deionized water is used to make the total of all components 100%.

[0144] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0145] (1) Take each component raw material according to weight percentage;

[0146] (2) Add 140 mL of deionized water to a 250 mL beaker, start the stirring device (120 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 13 min until completely dissolved.

[0147] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 28 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0148] (4) After pre-dispersing the thickener into a colloidal solution in 42°C warm water, slowly add it to the solution obtained in step (3) and stir for 180 minutes until it is uniform and transparent.

[0149] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 4.5, add deionized water to 250mL, stir for 7min, filter to remove impurity particles, and the product is obtained.

[0150] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0151] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 7wt% sulfuric acid solution for 1.5min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0152] (2) Passivation treatment: The pretreated copper foil is completely immersed in an environmentally friendly chromium-free passivating agent, and a passivation current is applied with a current density of 2A / dm². 2 The passivation solution temperature was room temperature (25℃), the passivation solution circulation flow rate was 50L / min, and the treatment time was 7s;

[0153] (3) Post-treatment: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 68°C for 42 seconds.

[0154] The passivation film in this embodiment is uniform and dense, with good corrosion resistance, and is suitable for general industrial applications.

[0155] Example 4

[0156] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0157] Sodium phytate 5.0%;

[0158] Tannic acid 3.0%;

[0159] Zinc sulfate 4.5%;

[0160] Glucose 2.0%;

[0161] Silane coupling agent (KH550) 4.5%;

[0162] Thickener (xanthan gum) 0.8%;

[0163] pH adjuster (phytic acid) 1.2%;

[0164] The remaining amount of deionized water is used to make the total of all components 100%.

[0165] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0166] (1) Take each component raw material according to weight percentage;

[0167] (2) Add 150 mL of deionized water to a 250 mL beaker, start the stirring device (130 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 11 min until completely dissolved.

[0168] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 22 minutes to allow the zinc ions to fully complex. Then add silane coupling agent and stir until completely dissolved.

[0169] (4) After pre-dispersing the thickener into a colloidal solution in 48°C warm water, slowly add it to the solution obtained in step (3) and stir for 190 minutes until it is uniform and transparent.

[0170] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.5, add deionized water to 250mL, stir for 6min, filter to remove impurity particles, and the product is obtained.

[0171] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0172] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 6wt% sulfuric acid solution for 1min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0173] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.15 MPa for 28 seconds;

[0174] (3) Post-treatment: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 75°C for 30 seconds.

[0175] The passivation film in this embodiment is slightly thin, but its adhesion and corrosion resistance still meet the basic requirements, making it suitable for cost-sensitive applications.

[0176] Example 5

[0177] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0178] Sodium phytate 7.5%;

[0179] Tannic acid 5.0%;

[0180] Zinc sulfate 3.0%;

[0181] 1.5% glucose;

[0182] 3.5% silane coupling agent (KH550 and KH560 in a 1:1 mass ratio);

[0183] Thickener (sodium carboxymethyl cellulose) 0.6%;

[0184] pH adjuster (phytic acid) 1.8%;

[0185] The remaining amount of deionized water is used to make the total of all components 100%.

[0186] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0187] (1) Take each component raw material according to weight percentage;

[0188] (2) Add 135 mL of deionized water to a 250 mL beaker, start the stirring device (160 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 15 min until completely dissolved.

[0189] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 26 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0190] (4) After pre-dispersing the thickener into a colloidal solution in 43°C warm water, slowly add it to the solution obtained in step (3) and stir for 200 minutes until it is uniform and transparent.

[0191] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 4.8, add deionized water to 250mL, stir for 9min, filter to remove impurity particles, and the product is obtained.

[0192] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0193] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 9wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0194] (2) Passivation treatment: The pretreated copper foil is completely immersed in an environmentally friendly chromium-free passivating agent, and a passivation current is applied at a current density of 1.0 A / dm². 2 The passivation solution temperature was room temperature (25℃), the passivation solution circulation flow rate was 50L / min, and the treatment time was 9s;

[0195] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 62℃ for 54s.

[0196] The passivation film in this embodiment has significantly enhanced corrosion resistance, but the film formation rate is slightly slower, making it suitable for applications with high corrosion resistance requirements.

[0197] Example 6

[0198] The environmentally friendly chromium-free passivating agent of this embodiment includes the following components by weight percentage:

[0199] Sodium phytate 6.5%;

[0200] Tannic acid 2.0%;

[0201] Zinc sulfate 4.0%;

[0202] Glucose 3.0%;

[0203] Silane coupling agent (KH550) 4.0%;

[0204] Thickener (xanthan gum to polyvinyl alcohol mass ratio 1:1, polyvinyl alcohol molecular weight 50,000 Da) 0.4%;

[0205] pH adjuster (phytic acid) 2.1%;

[0206] The remaining amount of deionized water is used to make the total of all components 100%.

[0207] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0208] (1) Take each component raw material according to weight percentage;

[0209] (2) Add 145 mL of deionized water to a 250 mL beaker, start the stirring device (140 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 10 min until completely dissolved.

[0210] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 24 minutes to allow the zinc ions to fully complex. Then add silane coupling agent and stir until completely dissolved.

[0211] (4) After pre-dispersing the thickener into a colloidal solution in 47°C warm water, slowly add it to the solution obtained in step (3) and stir for 170 minutes until it is uniform and transparent.

[0212] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.2, add deionized water to 250mL, stir for 5min, filter to remove impurity particles, and the product is obtained.

[0213] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0214] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 8wt% sulfuric acid solution for 1.5min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0215] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.25 MPa for 22 seconds;

[0216] (3) Post-treatment: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 78°C for 24 seconds.

[0217] The passivation film in this embodiment is uniform and has good self-healing function, making it suitable for scenarios where the self-healing performance of the film is highly required.

[0218] Comparative Example 1

[0219] This comparative example of an environmentally friendly, chromium-free passivating agent includes the following components by weight percentage:

[0220] Sodium phytate 7.0%;

[0221] Tannic acid 2.5%;

[0222] Zinc sulfate 3.5%;

[0223] Glucose 2.0%;

[0224] Silane coupling agent (KH550) 4.0%;

[0225] pH adjuster (phytic acid) 2.0%;

[0226] The remaining amount of deionized water is used to make the total of all components 100%.

[0227] The preparation method of this comparative example of an environmentally friendly chromium-free passivating agent includes the following steps:

[0228] (1) Take each component raw material according to weight percentage;

[0229] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 14 min until completely dissolved.

[0230] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 30 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0231] (4) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.0, add deionized water to 250mL, stir for 10min, filter to remove impurity particles, and the product is obtained.

[0232] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0233] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0234] (2) Passivation treatment: The pretreated copper foil is completely immersed in an environmentally friendly chromium-free passivating agent, and a passivation current is applied at a current density of 1.0 A / dm². 2 The passivation solution temperature was room temperature (25℃), the passivation solution circulation flow rate was 50L / min, and the treatment time was 8s;

[0235] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0236] Because no thickener was added in this comparative example, the passivating agent had an extremely low viscosity, almost like water, resulting in an excessively thin film, uneven coverage, significantly reduced corrosion resistance, and poor oxidation resistance.

[0237] Comparative Example 2

[0238] This comparative example of an environmentally friendly, chromium-free passivating agent includes the following components by weight percentage:

[0239] Sodium phytate 7.0%;

[0240] Tannic acid 2.5%;

[0241] Zinc sulfate 3.5%;

[0242] Glucose 2.0%;

[0243] Silane coupling agent (KH550) 4.0%;

[0244] Thickener (sodium carboxymethyl cellulose) 0.5%;

[0245] The remaining amount of deionized water is used to make the total of all components 100%.

[0246] The preparation method of this comparative example of an environmentally friendly chromium-free passivating agent includes the following steps:

[0247] (1) Take each component raw material according to weight percentage;

[0248] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 14 min until completely dissolved.

[0249] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 30 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0250] (4) After pre-dispersing the thickener into a colloidal solution in 45°C warm water, slowly add it to the solution obtained in step (3) and stir for 210 minutes until it is uniform and transparent.

[0251] (5) Add deionized water to 250mL, stir for 10min, filter to remove impurities and particles, and the product is ready.

[0252] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0253] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0254] (2) Passivation treatment: The pretreated copper foil is completely immersed in an environmentally friendly chromium-free passivating agent, and a passivation current is applied at a current density of 1.0 A / dm². 2 The passivation solution temperature was room temperature (25℃), the passivation solution circulation flow rate was 50L / min, and the treatment time was 8s;

[0255] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0256] In this comparative example, the uniformity and adhesion of the passivation film were affected because the pH of the system was not adjusted, but a protective film could still be formed.

[0257] Comparative Example 3

[0258] This comparative example of an environmentally friendly, chromium-free passivating agent includes the following components by weight percentage:

[0259] Sodium phytate 7.0%;

[0260] Tannic acid 2.5%;

[0261] Nickel sulfate 3.5%;

[0262] Glucose 2.0%;

[0263] Silane coupling agent (KH550) 4.0%;

[0264] Thickener (sodium carboxymethyl cellulose) 1.0%;

[0265] pH adjuster (phytic acid) 2.0%;

[0266] The remaining amount of deionized water is used to make the total of all components 100%.

[0267] The preparation method of the environmentally friendly chromium-free passivating agent in this embodiment includes the following steps:

[0268] (1) Take each component raw material according to weight percentage;

[0269] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 14 min until completely dissolved.

[0270] (3) Add nickel sulfate slowly, controlling the addition speed, stir for 30 minutes, then add silane coupling agent and stir until completely dissolved.

[0271] (4) After pre-dispersing the thickener into a colloidal solution in 45°C warm water, slowly add it to the solution obtained in step (3) and stir for 210 minutes until it is uniform and transparent.

[0272] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.0, add deionized water to 250mL, stir for 10min, filter to remove impurity particles, and the product is obtained.

[0273] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0274] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0275] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.2 MPa for 25 seconds;

[0276] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0277] In this embodiment, nickel sulfate is used instead of zinc sulfate. The resulting passivation film has similar adhesion and antioxidant properties to that in Example 2, and its salt spray resistance is improved. However, the cost of use is increased (the price of nickel sulfate is about 15-50 times that of zinc sulfate), making it suitable for copper foil applications with higher corrosion resistance requirements.

[0278] Comparative Example 4

[0279] This comparative example of an environmentally friendly, chromium-free passivating agent includes the following components by weight percentage:

[0280] Sodium phytate 7.0%;

[0281] Tannic acid 2.5%;

[0282] Zinc sulfate 3.5%;

[0283] Silane coupling agent (KH550) 4.0%;

[0284] Thickener (sodium carboxymethyl cellulose) 1.0%;

[0285] pH adjuster (phytic acid) 2.0%;

[0286] The remaining amount of deionized water is used to make the total of all components 100%.

[0287] The preparation method of this comparative example of an environmentally friendly chromium-free passivating agent includes the following steps:

[0288] (1) Take each component raw material according to weight percentage;

[0289] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate and tannic acid in sequence, and stir for 14 min until completely dissolved.

[0290] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 30 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0291] (4) After pre-dispersing the thickener into a colloidal solution in 45°C warm water, slowly add it to the solution obtained in step (3) and stir for 210 minutes until it is uniform and transparent.

[0292] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.0, add deionized water to 250mL, stir for 10min, filter to remove impurity particles, and the product is obtained.

[0293] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0294] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0295] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.2 MPa for 25 seconds;

[0296] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0297] In this comparative example, no glucose was added. The passivation solution viscosity decreased, the passivation film thickness decreased, the corrosion resistance and self-healing function were significantly weakened, the antioxidant performance was poor, and the passivation uniformity was poor.

[0298] Comparative Example 5

[0299] This comparative example of an environmentally friendly, chromium-free passivating agent includes the following components by weight percentage:

[0300] Sodium phytate 7.0%;

[0301] Tannic acid 2.5%;

[0302] Zinc sulfate 0.5%;

[0303] Glucose 2.0%;

[0304] Silane coupling agent (KH550) 4.0%;

[0305] Thickener (sodium carboxymethyl cellulose) 1.0%;

[0306] pH adjuster (phytic acid) 2.0%;

[0307] The remaining amount of deionized water is used to make the total of all components 100%.

[0308] The preparation method of this comparative example of an environmentally friendly chromium-free passivating agent includes the following steps:

[0309] (1) Take each component raw material according to weight percentage;

[0310] (2) Add 130 mL of deionized water to a 250 mL beaker, start the stirring device (180 rpm), add sodium phytate, tannic acid and glucose in sequence, and stir for 14 min until completely dissolved.

[0311] (3) Add zinc sulfate slowly, controlling the addition speed, and stir for 30 minutes to allow the zinc ions to fully complex. Then add the silane coupling agent and stir until completely dissolved.

[0312] (4) After pre-dispersing the thickener into a colloidal solution in 45°C warm water, slowly add it to the solution obtained in step (3) and stir for 210 minutes until it is uniform and transparent.

[0313] (5) Use a pH meter to measure the pH value, slowly add phytic acid to adjust the pH of the system to 5.0, add deionized water to 250mL, stir for 10min, filter to remove impurity particles, and the product is obtained.

[0314] The copper foil is surface treated using a prepared environmentally friendly chromium-free passivating agent, including the following steps:

[0315] (1) Pretreatment: The copper foil (thickness 6μm) that has not been passivated is immersed in 10wt% sulfuric acid solution for 2min for acid washing to remove the surface oxide layer, and then rinsed with clean water.

[0316] (2) Passivation treatment: Spray environmentally friendly chromium-free passivating agent onto the surface of the pretreated copper foil at a pressure of 0.2 MPa for 25 seconds;

[0317] (3) Post-processing: Take out the passivated copper foil, use a rubber roller to remove the residual passivation liquid on the surface, and then dry it with hot air at 70°C for 36 seconds.

[0318] The zinc sulfate addition in this comparative example was significantly lower than that in Example 2, resulting in a significant decrease in the density of the passivation film, mottled appearance of the passivation film, obvious color difference, increased resistance, and failure to meet corrosion resistance requirements.

[0319] The copper foils of the above embodiments and comparative examples were subjected to relevant performance tests, and the results are shown in Table 1 below:

[0320] Table 1 Comparison of copper foil performance after passivation treatment in the examples and comparative samples.

[0321]

[0322] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An environmentally friendly chromium-free passivating agent, characterized in that, Includes the following components by weight percentage: Sodium phytate 5.0%–10.0%; Tannic acid 1.0%–5.0%; Zinc sulfate 2.0%–5.0%; Glucose 1.0%–3.0%; Silane coupling agent 2.0%–6.0%; Thickener 0.1%–1.5%; pH adjuster 1%–3%; The remaining amount of deionized water is used to make the total of all components 100%.

2. The environmentally friendly chromium-free passivating agent as described in claim 1, characterized in that, Includes one or more of the following characteristics: (1) The weight percentage of sodium phytate in the chromium-free passivating agent is 6.0% to 8.0%; (2) The weight percentage of tannic acid in the chromium-free passivating agent is 2.0% to 3.0%; (3) The weight percentage of zinc sulfate in the chromium-free passivating agent is 3.0% to 4.5%; (4) The weight percentage of glucose in the chromium-free passivating agent is 1.5% to 2.5%; (5) The weight percentage of silane coupling agent in the chromium-free passivating agent is 3.0% to 5.0%; (6) The thickener in the chromium-free passivating agent has a weight percentage of 0.3% to 1.0%.

3. The environmentally friendly chromium-free passivating agent as described in claim 1 or 2, characterized in that, Includes one or more of the following characteristics: (a) The silane coupling agent is selected from any one or a combination of two of KH550 and KH560; (b) The thickener is selected from any one or a combination of sodium carboxymethyl cellulose, xanthan gum, and polyvinyl alcohol; (c) The pH adjuster is selected from phytic acid; (d) The pH of the environmentally friendly chromium-free passivating agent is 3.5 to 6.

5.

4. The method for preparing the environmentally friendly chromium-free passivating agent according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Add some deionized water to the reaction vessel, turn on the stirring, and add sodium phytate, tannic acid and glucose in sequence, stirring until completely dissolved; (2) Add zinc sulfate slowly while stirring, continue stirring to allow the reaction to proceed, then add silane coupling agent and continue stirring until completely dissolved; (3) Slowly add the thickener dispersion while stirring. After adding, continue stirring to ensure uniform dispersion. (4) Slowly add pH adjuster to adjust the pH of the system, add the remaining deionized water, stir to mix evenly, filter, and the product is obtained.

5. The preparation method of the environmentally friendly chromium-free passivating agent as described in claim 4, characterized in that, Step (1) includes one or more of the following features: (a) The weight of the deionized water mentioned above accounts for 50% to 60% of the total weight of the deionized water; (b) The stirring speed is 100-200 rpm; (c) The stirring time is 10 to 15 minutes.

6. The preparation method of the environmentally friendly chromium-free passivating agent as described in claim 4, characterized in that, In step (2), the continuous stirring time is 20 to 30 minutes.

7. The method for preparing the environmentally friendly chromium-free passivating agent as described in claim 4, characterized in that, Step (3) includes one or more of the following features: (a) The preparation method of the thickener dispersion includes adding the thickener to warm water at 40-50°C and dispersing it evenly; (b) The stirring rate is 150–300 rpm; (c) The stirring time is 30 to 60 minutes.

8. The preparation method of the environmentally friendly chromium-free passivating agent as described in claim 4, characterized in that, Includes one or more of the following characteristics: (a) In step (4), the pH of the system is tested while adding the pH adjuster; (b) In step (4), the pH of the system is 3.5–6.5; (c) In step (4), the stirring time is 5 to 10 minutes; (d) In step (5), the filtering device is a filter screen.

9. A metal surface passivation treatment process, characterized in that, Includes the following steps: (1) Pretreatment: The metal surface is pickled and washed with water to obtain the pretreated metal; (2) Passivation treatment: The pretreated metal is immersed in the environmentally friendly chromium-free passivating agent as described in any one of claims 1 to 3, or the environmentally friendly chromium-free passivating agent as described in any one of claims 1 to 3 is sprayed onto the surface of the pretreated metal to form a dense passivation film on the metal surface. (3) Post-treatment: Remove the residual environmentally friendly chromium-free passivating agent from the metal surface and dry it.

10. The method for surface treatment of copper foil using an environmentally friendly chromium-free passivating agent as described in claim 9, characterized in that, Includes one or more of the following characteristics: (a) In step (1), the metal is selected from copper foil with a thickness of 6 to 10 μm; (b) In step (1), the washing medium used for pickling is a sulfuric acid solution with a concentration of 5wt% to 10wt%, and the pickling time is 1 to 2 minutes; (c) In step (2), the temperature of the environmentally friendly chromium-free passivating agent is room temperature; (d) In step (2), while immersing the sample in an environmentally friendly chromium-free passivating agent, an electric current is applied at a density of 0.5–2 A / dm². 2 The treatment time is 5-10 seconds; or it can be immersed in an environmentally friendly chromium-free passivating agent without applying current, and the treatment time is 10-20 minutes. (e) In step (2), the spraying pressure is 0.1 to 0.3 MPa and the time is 20 to 30 s; (f) In step (3), the method for removing the residual environmentally friendly chromium-free passivating agent on the surface of the copper foil is to use a rubber roller to press it; (g) In step (3), the drying is hot air drying at a temperature of 60-80°C for 30-60 seconds.

Images