A high-surface-energy multifunctional trivalent chromium passivator as well as a preparation method and application thereof

Abstract

The present application relates to a kind of high surface energy multifunctional trivalent chromium passivator and its preparation method and application.The trivalent chromium passivator provided by the present application is made of trivalent chromium compound, inorganic acid, silane coupling agent, film-forming aid, resin, surface energy aid and water.The trivalent chromium passivator provided by the present application introduces hydrophilic group by adding surface energy aid, not only improves the compactness, adhesive property, lubricating property, surface energy and dyne value of passivation film, but also improves the stability of passivation film structure, is suitable for a variety of strip steel.The present application meets the requirements of civil construction, photovoltaic power generation, electric power communication, household appliances and automobile manufacturing and other industries on the surface performance of strip steel.The preparation method of the passivator is simple, stable, low in preparation cost, and suitable for steel plant to expand production.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, specifically relating to a high surface energy multifunctional trivalent chromium passivating agent, its preparation method, and its application. Background Technology

[0002] Galvanized, aluminized silicon, and zinc-aluminum-magnesium steel strips are widely used in industries such as civil engineering, photovoltaic power generation, power communication, home appliances, and automobile manufacturing. For example, in the photovoltaic, construction, and electromechanical industries, stamping and bending processes are often used to process parts; in the automotive and home appliance industries, there are high requirements for the coating performance of steel strips. Magnesium in zinc-aluminum-magnesium coatings is relatively reactive and easily corrodes and blackens when exposed to humid air for a long time, affecting the appearance of the product surface and its subsequent use. Moreover, steel plates are prone to surface blackening during stamping and bending, usually due to friction between the steel plate and equipment. The necessity of passivation treatment is to improve the corrosion resistance, blackening resistance, and other related properties of steel strips. Passivation is an effective means of improving the corrosion resistance, blackening resistance, lubricity, and many other related properties of steel coils, and is widely used in the steel industry. Chromate treatment was widely used for a long time; in the oxide film after passivation, chromium exists in trivalent and hexavalent forms. However, hexavalent chromium is a potent carcinogen, posing a significant threat to the environment and human health. In this context, trivalent chromium passivation technology has emerged. Trivalent chromium shares many similarities with hexavalent chromium, and although trivalent chromium passivation technology has made some progress, there is still room for improvement. For example, the surface energy of the passivation film formed by current trivalent chromium passivating agents needs to be improved. Traditional trivalent chromium production strips have large contact angles and low surface energy (rapid dyne decay), which may affect its application in certain specific fields and cannot meet the needs of high-end applications. For instance, in automobile manufacturing, the bonding strength between steel sheets and electrophoretic paint needs to be extremely high, but the surface energy of traditional trivalent chromium passivation films is insufficient (usually below 40 mN / m), resulting in poor adhesion. In applications requiring high coating adhesion, the surface tension of the substrate is also crucial. It is necessary to ensure the wettability, spreadability, and adsorption capacity of the passivation film on the substrate surface. A passivation film with high surface energy can better bond with subsequent coatings, improving the overall protective effect. Therefore, developing a three-in-one multifunctional passivating agent with high surface tension and corrosion resistance is essential. Summary of the Invention

[0003] This invention aims to provide a high surface energy, multifunctional trivalent chromium passivating agent, its preparation method, and its applications. Through careful design and optimization of the passivating agent's composition, it not only adapts to various steel strips and plates, forming a passivation film with high surface energy to meet specific performance requirements such as coating adhesion, paintability, and adhesiveness, but also possesses excellent corrosion resistance and other functions. Simultaneously, a simple, efficient, and environmentally friendly preparation method has been developed to ensure the large-scale industrial production of this passivating agent and its widespread application in the field of metal surface treatment, promoting the industry's development towards green and high-performance directions.

[0004] The trivalent chromium passivation agent provided by this invention is composed of the following substances in parts by weight: 20-25% trivalent chromium compound, 3-7.5% inorganic acid, 5-9% silane coupling agent, 1-5% film-forming aid, 2-5% resin, 0.1-0.5% surface energy aid, and water as the balance.

[0005] The trivalent chromium compound is one or two of chromium sulfate, chromium nitrate, chromium phosphate, or chromium dihydrogen phosphate; the inorganic acid is at least one of sulfuric acid, phosphoric acid, nitric acid, or hydrofluoric acid; the silane coupling agent is one or two of aminosilane coupling agents, vinylsilane coupling agents, or epoxysilane coupling agents; the film-forming aid is at least one of cobalt nitrate, sodium nitrate, ammonium fluoride, ammonium hydrogen fluoride, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, nickel sulfate, nickel nitrate, nickel chloride, or nickel carbonate; the resin is at least one of water-soluble acrylic resin, water-soluble epoxy resin, and water-soluble polyester resin; and the surface energy aid is at least one of organosilicon-type surface energy aid, polyether block-type surface energy aid, or composite surface energy aid.

[0006] A high surface energy multifunctional trivalent chromium passivating agent and its preparation method include the following steps: preparing materials according to the above ratio and placing them in water, adding inorganic acid sequentially while stirring at a uniform speed for 10-40 min, adjusting the pH value to 1-2; adding silane coupling agent and stirring for 20-80 min to completely hydrolyze the silane coupling agent; adding film-forming aid and stirring for 10-60 min; adding resin and stirring for 5-30 min; adding trivalent chromium compound and stirring for 10-30 min; adding surface energy aid and stirring for 10-30 min.

[0007] The preparation method of the above surface energy additive is as follows:

[0008] Step 1: Stir 30-60 parts by weight of functional monomer, 0.5-2.0 parts by weight of plasticizer and 0.5-1.5 parts by weight of crosslinking agent thoroughly for 30 minutes, dehydrate under vacuum at 110℃~120℃, and then react thoroughly at 150℃~200℃ for 2-3 hours. Add 5-10 parts by weight of catalyst dropwise and react for 1-2 hours. Then add 10-20 parts by weight of initiator and solvent and continue the reaction for 3-5 hours to obtain the preproduct.

[0009] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation and washing to remove unreacted monomers and byproducts to obtain the target product.

[0010] The above-mentioned surface energy additive is prepared from the following substances:

[0011] The functional monomers are 1-3 of the following: siloxane, fatty acid, polyol, polyether, polyether siloxane, polyester, polyamide, or polycarbonate acrylate; the plasticizer is at least one of the following: p-toluenesulfonic acid, xylenesulfonic acid, or sodium methylbenzenesulfonate; the crosslinking agent is at least one of the following: ethyl acetate, sodium dihydrogen propionate, methyltrichlorosilane, dimethyldichlorosilane, or epoxysilane; the catalyst is at least one of the following: sulfuric acid, formic acid, hydrochloric acid, sodium methoxide, or potassium hydroxide; and the initiator is at least one of the following: azobisisobutyronitrile, di-tert-butyl peroxide, azobisisoheptanenitrile, or benzoyl peroxide.

[0012] The trivalent chromium passivating agent described in this invention is suitable for continuous hot-dip galvanizing, aluminizing, and zinc-aluminum-magnesium galvanizing production lines for steel strips in steel mills. It achieves the multifunctionality of the trivalent chromium passivating agent, reducing the manpower and material costs associated with frequent agent replacements during use. Simultaneously, through formulation design and process optimization of the trivalent chromium passivating agent, a composite film layer with both high surface energy and strong adhesion is formed on the metal surface, thereby improving the bonding strength between the metal and coatings, adhesives, or other materials.

[0013] The beneficial effects of this invention are:

[0014] I. Superior performance and diverse functions

[0015] (i) Outstanding high surface energy characteristics

[0016] Passivating agents, by adding surface energy additives and introducing hydrophilic groups, increase the hydrophilicity of the passivation film, resulting in a passivation film with significantly high surface energy characteristics. This represents a qualitative leap in metal surface treatment. In coating applications, high surface energy greatly enhances the adhesion between the passivation film and the coating, effectively preventing coating peeling and blistering, extending coating lifespan, and improving protective performance. Simultaneously, high surface energy improves the wettability of the metal surface, allowing the passivation solution to spread evenly, greatly improving the quality and uniformity of the steel strip.

[0017] (ii) Excellent multi-functional performance

[0018] Chemical adaptability:

[0019] (1) Adapting to differences in the activity of coating metals: The metal activity, electrode potential, and corrosion mechanism of zinc-plated layers (zinc-based), aluminum-silicon layers (aluminum-silicon alloy), and zinc-aluminum-magnesium layers (zinc-aluminum-magnesium multi-element alloy) are different. This passivating agent adjusts the trivalent chromium salt concentration, pH value, and additive components to match the redox potential of the passivation solution with different coatings, avoiding excessive corrosion (such as whitening caused by over-corrosion of zinc-plated layers) or insufficient adhesion of the passivation film (such as violent reaction caused by the reactivity of magnesium in zinc-aluminum-magnesium layers).

[0020] (2) Inhibiting selective dissolution of coating metals: Magnesium in zinc-aluminum-magnesium coatings is highly reactive, and ordinary passivating agents can easily cause magnesium to dissolve preferentially, damaging the coating structure. This passivating agent, by adding functional film-forming aids, forms a multi-component complex during the passivation process, inhibiting excessive dissolution of magnesium, while promoting the uniform reaction of zinc, aluminum, and magnesium, ensuring the chemical stability of different coatings.

[0021] Universality of film composition and structure and superior corrosion resistance:

[0022] The passivation films are all based on trivalent chromium-metal oxide hydroxide as the framework, and introduce silicon-oxygen bonds (-Si-O-Si-) and organic functional groups (such as hydroxyl and carboxyl groups) through silane coupling agents and resins to form an inorganic-organic hybrid film layer. This film structure can enhance the adhesion on the zinc-plated layer surface, fill the gaps between alloy particles on the aluminum-silicon-plated layer surface, and cover magnesium oxide products on the zinc-aluminum-magnesium layer surface, thus forming a passivation film with uniform thickness, no missed plating, and no over-corrosion on different coating surfaces. This allows the steel plate to serve stably for a long time in harsh environments, significantly reducing maintenance and replacement costs.

[0023] Compatibility and processability of surface energy modulated surfaces:

[0024] By adjusting the ratio of silane coupling agent and surface energy additive, the surface energy (such as polar group density) of the passivation film can be adapted to the surface energy requirements of different coatings. For example, the surface polarity of zinc plating is relatively high, and a high surface energy film can enhance the adhesion to subsequent coatings (such as paints and coatings); the surface of zinc-aluminum-magnesium plating is prone to forming a low surface energy oxide layer due to the presence of magnesium. The passivating agent increases its surface energy by introducing polar groups (such as hydroxyl groups), improves lubrication during stamping, reduces frictional blackening, and solves the problem of blackening of the passivation film after stamping.

[0025] Second, green and environmentally friendly, in line with the trend.

[0026] This invention uses trivalent chromium as its core component, significantly reducing harm to the environment and human health. The preparation process eliminates toxic heavy metals, generates minimal pollutants, and can meet emission standards with simple treatment, fully complying with current stringent environmental regulations. This powerfully promotes the green transformation of the metal surface treatment industry and provides technical support for sustainable development.

[0027] III. Simple process, economical and efficient

[0028] The preparation method is simple to operate and easy to master, requiring no complex equipment or high-end technology, thus lowering the technological threshold for production. Furthermore, the raw materials are widely available and inexpensive, resulting in lower costs compared to complex chromium-free passivation technologies while maintaining high performance. Simultaneously, due to the excellent performance of the passivation film, it significantly reduces maintenance and replacement costs during the subsequent use of the produced metal workpieces. Considering the entire lifecycle, the economic benefits are significant, demonstrating excellent market potential and application value. Detailed Implementation

[0029] In the following examples, the water-soluble epoxy resin, water-soluble acrylic resin, and water-soluble polyester resin were all purchased from Wanhua Chemical Group Co., Ltd., and other raw materials were all commercially available.

[0030] Example 1

[0031] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0032] Chromium phosphate 20%, phosphoric acid 5%, nitric acid 2%, aminosilane coupling agent 6%, hydrofluoric acid 0.5%, cobalt nitrate 1%, ammonium dihydrogen phosphate 2%, nickel carbonate 1%, nickel nitrate 1%, water-soluble epoxy resin 2%, organosilicon surface energy additive 0.3%, polyether block surface energy additive 0.2%, water balance.

[0033] (II) Preparation method:

[0034] 1. The preparation method of organosilicon-based surface energy additives is as follows:

[0035] Step 1: Mix 20 parts by weight of siloxane, 10 parts by weight of fatty acid, 10 parts by weight of polyether, 10 parts by weight of polycarbonate, 0.5 parts by weight of xylenesulfonic acid, 1.0 parts by weight of ethyl acetate, and 0.5 parts by weight of sodium dihydrogen propionate thoroughly for 30 minutes. Dehydrate under vacuum at 110°C, then react thoroughly at 180°C for 3 hours. Add 5 parts by weight of sulfuric acid and react for 2 hours. Then add 15 parts by weight of azobisisobutyronitrile and the remainder of pure water, and continue reacting for 4 hours to obtain the preproduct.

[0036] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0037] 2. The preparation method of polyether block surface energy additive is as follows:

[0038] Step 1: Mix 30 parts by weight of polyether, 15 parts by weight of polycarbonate, 0.5 parts by weight of xylenesulfonic acid and 1.0 parts by weight of sodium dihydrogen propionate thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 200°C for 3 hours. Add 5 parts by weight of sulfuric acid and react for 2 hours. Then add 15 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 4 hours to obtain the preproduct.

[0039] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0040] 3. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0041] In pure water, under medium-speed stirring at 500 r / min, nitric acid was added and stirred for 10 min; phosphoric acid was added and stirred for 10 min; hydrofluoric acid was added and stirred for 10 min; aminosilane coupling agent was added and stirred for 30 min to allow complete hydrolysis of the silane coupling agent; cobalt nitrate was added and stirred for 10 min; ammonium dihydrogen phosphate was added and stirred for 10 min; nickel carbonate was added and stirred for 10 min; nickel nitrate was added and stirred for 10 min; organosilicon surface energy aid was added and stirred for 10 min; polyether block surface energy aid was added and stirred for 10 min; water-soluble epoxy resin was added and stirred for 5 min; chromium nitrate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0042] Example 2

[0043] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0044] Chromium sulfate 15%, chromium phosphate 10%, phosphoric acid 5%, nitric acid 2%, epoxy silane coupling agent 6%, hydrofluoric acid 0.5%, ammonium dihydrogen phosphate 2%, ammonium fluoride 1%, nickel sulfate 1%, water-soluble polyester resin 2%, composite surface energy additive 0.2%, water balance.

[0045] (II) Preparation method:

[0046] 1. The preparation method of the composite surface energy additive is as follows:

[0047] Step 1: Mix 10 parts by weight of polyamide, 15 parts by weight of polyether, 10 parts by weight of polycarbonate, 2.0 parts by weight of xylenesulfonic acid and 0.5 parts by weight of methyltrichlorosilane thoroughly for 30 minutes, dehydrate under vacuum at 120°C, and then react thoroughly at 200°C for 2 hours. Add 5 parts by weight of potassium hydroxide and react for another 2 hours. Then add 5 parts by weight of azobisisobutyronitrile, 5 parts by weight of benzoyl peroxide and the remainder of pure water, and continue the reaction for 5 hours to obtain the preproduct.

[0048] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0049] 2. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0050] In pure water, under medium-speed stirring at 500 r / min, nitric acid was added and stirred for 10 min; phosphoric acid was added and stirred for 10 min; hydrofluoric acid was added and stirred for 10 min; epoxy silane coupling agent was added and stirred for 30 min to allow the silane coupling agent to be completely hydrolyzed; ammonium fluoride was added and stirred for 10 min; ammonium dihydrogen phosphate was added and stirred for 10 min; nickel sulfate was added and stirred for 10 min; water-soluble polyester resin was added and stirred for 5 min; composite surface energy additive was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; chromium sulfate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0051] Example 3

[0052] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0053] Chromium sulfate 15%, chromium phosphate 10%, phosphoric acid 5%, epoxy silane coupling agent 3%, amino silane coupling agent 3%, hydrofluoric acid 0.5%, ammonium dihydrogen phosphate 2%, sodium nitrate 1%, nickel chloride 1%, water-soluble polyester resin 2%, water-soluble acrylic resin 3%, composite surface energy additive 0.1%, organosilicon surface energy additive 0.2%, water balance.

[0054] (II) Preparation method:

[0055] 1. The preparation method of composite surface energy additives is as follows:

[0056] Step 1: Mix 20 parts by weight of fatty acid, 5 parts by weight of polyol, 5 parts by weight of polycarbonate, 1.0 part by weight of xylenesulfonic acid, 0.5 parts by weight of sodium methylbenzenesulfonate, 0.2 parts by weight of sodium dihydrogen propionate, and 0.5 parts by weight of methyltrichlorosilane thoroughly for 30 minutes. Dehydrate under vacuum at 120°C, then react thoroughly at 180°C for 2 hours. Add 3 parts by weight of sodium methoxide and 5 parts by weight of potassium hydroxide, and react for 1 hour. Then add 15 parts by weight of azobisisobutyronitrile, 5 parts by weight of benzoyl peroxide, and the remainder pure water, and continue reacting for 3 hours to obtain the preproduct.

[0057] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0058] 2. The preparation method of organosilicon-based surface energy additives is as follows:

[0059] Step 1: Stir 30 parts by weight of fatty acid, 0.5 parts by weight of xylenesulfonic acid and 0.5 parts by weight of methyltrichlorosilane thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 150°C for 3 hours. Add 5 parts by weight of potassium hydroxide and react for 2 hours. Then add 20 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 3 hours to obtain the preproduct.

[0060] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0061] 3. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0062] In pure water, under medium-speed stirring at 500 r / min, phosphoric acid was added sequentially and stirred for 10 min; epoxy silane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; amino silane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; hydrofluoric acid was added and stirred for 10 min; sodium nitrate was added and stirred for 10 min; ammonium dihydrogen phosphate was added and stirred for 10 min; nickel chloride was added and stirred for 10 min; water-soluble polyester resin was added and stirred for 5 min; water-soluble acrylic resin was added and stirred for 5 min; composite surface energy aid was added and stirred for 10 min; organosilicon surface energy aid was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; chromium sulfate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0063] Example 4

[0064] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0065] Chromium nitrate 5%, chromium phosphate 15%, phosphoric acid 2%, nitric acid 1%, aminosilane coupling agent 6%, hydrofluoric acid 0.5%, ammonium dihydrogen phosphate 2%, water-soluble polyester resin 2%, water-soluble acrylic resin 1%, organosilicon surface energy additive 0.5%, water balance.

[0066] (II) Preparation method:

[0067] 1. The preparation method of the organosilicon-type surface energy additive is as follows:

[0068] Step 1: Mix 15 parts by weight of polyol, 15 parts by weight of polycarbonate, 1.0 part by weight of sodium methylbenzenesulfonate and 1.0 part by weight of dimethyldichlorosilane thoroughly for 30 minutes, dehydrate under vacuum at 115°C, and then react thoroughly at 200°C for 3 hours. Add 10 parts by weight of hydrochloric acid and react for 2 hours. Then add 10 parts by weight of benzoyl peroxide and the remainder water and continue reacting for 5 hours to obtain the preproduct.

[0069] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0070] 2. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0071] In pure water, under medium-speed stirring at 500 r / min, phosphoric acid was added and stirred for 10 min; nitric acid was added and stirred for 10 min; aminosilane coupling agent was added and stirred for 30 min to allow complete hydrolysis of the silane coupling agent; hydrofluoric acid was added and stirred for 10 min; ammonium dihydrogen phosphate was added and stirred for 10 min; water-soluble polyester resin was added and stirred for 5 min; water-soluble acrylic resin was added and stirred for 5 min; organosilicon surface energy additive was added and stirred for 10 min; chromium nitrate was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0072] Example 5

[0073] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0074] Chromium nitrate 10%, chromium phosphate 10%, phosphoric acid 2%, nitric acid 1.5%, aminosilane coupling agent 3%, vinylsilane coupling agent 3%, nickel carbonate 1%, ammonium dihydrogen phosphate 2%, water-soluble polyester resin 2%, water-soluble acrylic resin 1%, organosilicon surface energy additive 0.1%, composite surface energy additive 0.1%, water balance.

[0075] (II) Preparation method:

[0076] 1. The preparation method of organosilicon-based surface energy additives is as follows:

[0077] Step 1: Stir 30 parts by weight of siloxane, 0.5 parts by weight of sodium methylbenzenesulfonate and 1.0 parts by weight of epoxysilane thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 150°C for 3 hours. Add 5 parts by weight of sulfuric acid and react for 2 hours. Then add 15 parts by weight of benzoyl peroxide and the remainder of pure water and continue to react for 3 hours to obtain the preproduct.

[0078] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0079] 2. The preparation method of the composite surface energy additive is as follows:

[0080] Step 1: Mix 10 parts by weight of polyol, 15 parts by weight of polyether, 20 parts by weight of polycarbonate, 1.0 parts by weight of sodium methylbenzenesulfonate and 0.8 parts by weight of dimethyldichlorosilane thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 200°C for 3 hours. Add 6 parts by weight of sulfuric acid and 2 parts by weight of formic acid, react for 2 hours, then add 15 parts by weight of benzoyl peroxide and the remainder of pure water, and continue the reaction for 3 hours to obtain the preproduct.

[0081] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0082] 3. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0083] In pure water, under medium-speed stirring at 500 r / min, phosphoric acid was added and stirred for 10 min; nitric acid was added and stirred for 10 min; aminosilane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; vinylsilane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; nickel carbonate was added and stirred for 10 min; ammonium dihydrogen phosphate was added and stirred for 10 min; water-soluble polyester resin was added and stirred for 5 min; water-soluble acrylic resin was added and stirred for 5 min; organosilicon surface energy aid was added and stirred for 10 min; composite surface energy aid was added and stirred for 10 min; chromium nitrate was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0084] Example 6

[0085] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0086] Chromium nitrate 10%, Chromium dihydrogen phosphate 10%, Sulfuric acid 2%, Nitric acid 2%, Epoxy silane coupling agent 6%, Vinyl silane coupling agent 3%, Nickel carbonate 1%, Nickel nitrate 0.5%, Ammonium bifluoride 0.5%, Water-soluble epoxy resin 2%, Polyether block surface energy additive 0.2%, Composite surface energy additive 0.1%, Water balance.

[0087] (II) Preparation method:

[0088] 1. The preparation method of polyether block surface energy additive is as follows:

[0089] Step 1: Mix 15 parts by weight of polyether, 15 parts by weight of polyester, 0.5 parts by weight of p-toluenesulfonic acid and 0.5 parts by weight of epoxysilane thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 200°C for 3 hours. Add 5 parts by weight of sodium methoxide and react for 2 hours. Then add 10 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 5 hours to obtain the preproduct.

[0090] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0091] 2. The preparation method of the composite surface energy additive is as follows:

[0092] Step 1: Mix 10 parts by weight of polyether, 10 parts by weight of polyether siloxane, 15 parts by weight of polycarbonate acrylate, 0.5 parts by weight of p-toluenesulfonic acid, 0.5 parts by weight of sodium methylbenzenesulfonate, 0.2 parts by weight of ethyl acetate, and 0.6 parts by weight of epoxy silane thoroughly for 30 minutes. Dehydrate under vacuum at 110°C, then react thoroughly at 180°C for 3 hours. Add 10 parts by weight of sodium methoxide and react for 1 hour. Then add 5 parts by weight of azobisisobutyronitrile, 10 parts by weight of benzoyl peroxide, and the remainder pure water, and continue reacting for 5 hours to obtain the preproduct.

[0093] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0094] 3. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0095] In pure water, under medium-speed stirring at 500 r / min, sulfuric acid was added and stirred for 10 min; nitric acid was added and stirred for 10 min; epoxy silane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; vinyl silane coupling agent was added and stirred for 30 min to completely hydrolyze the silane coupling agent; nickel carbonate was added and stirred for 10 min; nickel nitrate was added and stirred for 10 min; ammonium bifluoride was added and stirred for 10 min; water-soluble epoxy resin was added and stirred for 5 min; polyether block surface energy aid was added and stirred for 10 min; composite surface energy aid was added and stirred for 10 min; chromium nitrate was added and stirred for 10 min; chromium dihydrogen phosphate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0096] Example 7

[0097] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0098] Chromium phosphate 15%, Chromium dihydrogen phosphate 5%, Sulfuric acid 2%, Nitric acid 1%, Epoxy silane coupling agent 6%, Ammonium bifluoride 1%, Water-soluble epoxy resin 1%, Water-soluble acrylic resin 2%, Polyether block surface energy additive 0.5%, Water balance.

[0099] (II) Preparation method:

[0100] 1. The preparation method of polyether block surface energy additive is as follows:

[0101] Step 1: Stir 30 parts by weight of polyether, 0.5 parts by weight of p-toluenesulfonic acid and 1.0 parts by weight of ethyl acetate thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 150°C for 3 hours. Add 10 parts by weight of hydrochloric acid and react for 1 hour. Then add 20 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 3 hours to obtain the preproduct.

[0102] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0103] 2. The preparation method of the composite surface energy additive is as follows:

[0104] Step 1: Stir 30 parts by weight of polycarbonate acrylate, 2.0 parts by weight of p-toluenesulfonic acid and 0.5 parts by weight of ethyl acetate thoroughly for 30 minutes, dehydrate under vacuum at 110°C, and then react thoroughly at 200°C for 2 hours. Add 10 parts by weight of hydrochloric acid and react for 1 hour. Then add 10 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 3-5 hours to obtain the preproduct.

[0105] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0106] 3. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0107] In pure water, under medium-speed stirring at 500 r / min, sulfuric acid was added and stirred for 10 min; nitric acid was added and stirred for 10 min; epoxy silane coupling agent was added and stirred for 30 min to allow complete hydrolysis of the silane coupling agent; ammonium bifluoride was added and stirred for 10 min; water-soluble epoxy resin was added and stirred for 5 min; water-soluble acrylic resin was added and stirred for 5 min; polyether block surface energy additive was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; chromium dihydrogen phosphate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0108] Example 8

[0109] (I) Composition of high surface energy multifunctional trivalent chromium passivating agent:

[0110] Chromium phosphate 20%, chromium sulfate 5%, phosphoric acid 4%, nitric acid 2%, aminosilane coupling agent 5%, sodium nitrate 1%, hydrofluoric acid 1%, ammonium fluoride 2%, water-soluble acrylic resin 2%, organosilicon surface energy additive 0.1%, water balance.

[0111] (II) Preparation method:

[0112] 1. The preparation method of organosilicon-based surface energy additives is as follows:

[0113] Step 1: Stir 20 parts by weight of siloxane, 15 parts by weight of polycarbonate, 1.5 parts by weight of sodium methylbenzenesulfonate and 0.6 parts by weight of ethyl acetate thoroughly for 30 minutes. Dehydrate under vacuum at 110°C, then react thoroughly at 160°C for 3 hours. Add 8 parts by weight of potassium hydroxide and react for 1 hour. Then add 15 parts by weight of azobisisobutyronitrile and the remainder pure water, and continue to react for 4 hours to obtain the preproduct.

[0114] Step 2: Cool the preproduct obtained in Step 1 to room temperature, and then perform distillation, washing, and decolorization to remove unreacted monomers and byproducts to obtain the target product.

[0115] 2. The preparation method of the high surface energy multifunctional trivalent chromium passivating agent is as follows:

[0116] In pure water, under medium-speed stirring at 500 r / min, phosphoric acid was added and stirred for 10 min; nitric acid was added and stirred for 10 min; aminosilane coupling agent was added and stirred for 30 min to allow complete hydrolysis of the silane coupling agent; sodium nitrate was added and stirred for 10 min; hydrofluoric acid was added and stirred for 10 min; ammonium fluoride was added and stirred for 10 min; water-soluble acrylic resin was added and stirred for 5 min; organosilicon surface energy aid was added and stirred for 10 min; chromium phosphate was added and stirred for 10 min; chromium sulfate was added and stirred for 10 min; the mixture was stirred until homogeneous to obtain the target product.

[0117] Example 9

[0118] Application of high surface energy multifunctional trivalent chromium passivating agents

[0119] The operation method is as follows: The high surface energy multifunctional trivalent chromium passivating agent prepared in Examples 1-8 of this invention is applied to the surface of a steel strip using a roller coating method to form a passivation film. Specifically, the steel plate (aluminized silicon, hot-dip galvanized, zinc-aluminum-magnesium) is degreased, washed, and dried. The agent prepared in Examples 1-8 is then applied using a roller coating machine for 3-5 seconds, dried at 60-80°C for 5-15 seconds, forming a passivation film on the surface of the steel plate.

[0120] The testing method for performance detection is as follows:

[0121] Salt spray resistance: Refer to GB / T 10125-2012, Neutral salt spray test (NSS) conditions: analytical grade NaCl, concentration 50±0.5 g / L, pH value: 6.5-7.2, test chamber temperature: 35±2℃, saturation tank temperature: 45℃, spray rate: 1.5-2ml / h.

[0122] Moisture and heat resistance: ΔE was measured using a colorimeter after being placed at 50℃×95%RH×120hr.

[0123] Alkali resistance: After spraying with a degreasing agent (pH=12.5) at 60℃ for 3 minutes, the ΔE was measured using a colorimeter.

[0124] Water resistance: ΔE was measured using a colorimeter after immersion in boiling water for 1 hour.

[0125] High temperature resistance: 300℃×20min, ΔE was measured using a colorimeter.

[0126] Solvent resistance: The film was rubbed back and forth 20 times under a load of 500g with MEK (butanone) and EtOH (80% alcohol), respectively. The changes in the appearance of the film were observed, and ΔE was measured with a colorimeter.

[0127] Coating performance: Amino alkyd coating, cross-cut (1*1mm 100 grids) + 7mm cupping followed by 3M tape tearing, and 9J impact test using an impact tester.

[0128] Lubricity: The coefficient of sliding friction between the plates was determined using a reciprocating friction tester.

[0129] Dyne value: Draw lines on the surface using different types of dyne pens and observe the diffusion of the lines.

[0130] Adhesiveness: Measured using an adhesive strength tester.

[0131] Experimental results: The humid heat resistance ΔE of galvanized and aluminized silicon sheets is ≤1.81, the humid heat resistance ΔE of zinc-aluminum-magnesium sheets is <3, the high temperature resistance ΔE is ≤2.06 (industry standard: humid heat resistance of galvanized and aluminized silicon sheets ΔE <5, zinc-aluminum-magnesium sheets ΔE <8, high temperature resistance ΔE <3), the water resistance ΔE is ≤1.52, the alkali resistance ΔE is ≤1.98, and the solvent resistance ΔE is <1.51 (industry standard: water resistance ΔE <3, alkali resistance ΔE <3, solvent resistance ΔE <3), and the coating performance is excellent. The addition of silane coupling agents significantly improves corrosion resistance. Galvanized steel sheets can withstand 200 hours of neutral salt spray testing, aluminized silicon sheets 300 hours, and zinc-aluminum-magnesium sheets over 500 hours, with a corrosion area of ​​<5% (industry standard: 72-hour neutral salt spray, corrosion area <5%). The addition of resin and surface energy additives improves the lubricity of the steel surface, resulting in a surface dynamic friction coefficient ≤0.195 (compared to ordinary trivalent chromium passivated sheets which lack lubricity and have dynamic friction coefficients >0.3). This effectively protects the substrate during stamping deformation, reduces the contact angle, and enhances surface energy and adhesion. Under normal temperature conditions, the dyne value remains above 40 after more than 6 months without decay (compared to traditional trivalent chromium, which has a dyne value below 36 after 20 days under the same conditions, exhibiting poor adhesion).

[0132] The physicochemical properties and performance comparisons are shown in Table 1:

[0133] Table 1. Physicochemical properties and performance of the passivating agents obtained in the examples and comparative examples.

[0134]

Claims

1. A high surface energy multifunctional trivalent chromium passivating agent, characterized in that, According to the percentage by weight, comprising the following components: Trivalent chromium compound 20-25%; inorganic acid 3-7.5%; silane coupling agent 5-9%; film forming aid 1-5%; resin 2-5%; surface energy aid 0.1-0.5%; water balance; The surface energy aid is at least one of silicone type surface energy aid, polyether block type surface energy aid or composite type surface energy aid. The preparation method of surface energy aid comprises the following steps: Step one: 30-60 parts by weight of functional monomer, 0.5-2.0 parts by weight of plasticizer and 0.5-1.0 parts by weight of crosslinking agent are fully stirred for 30 minutes, vacuum dehydration at 110-120℃, then fully reacted at 150-200℃ for 2-3 hours, add 5-10 parts by weight of catalyst, react for 1-2 hours, then add 5-30 parts by weight of initiator and solvent, continue to react for 3-5 hours to obtain a pre-product; Step two: the pre-product obtained in step one is cooled to room temperature, and then distilled, washed and decolorized to remove unreacted monomers and by-products to obtain the target product; The functional monomer is one or more of siloxane, fatty acid, polyol, polyether, polyether siloxane, polyester, polyamide or polycarbon acrylate, the plasticizer is at least one of p-toluene sulfonic acid, xylene sulfonic acid or sodium methyl benzene sulfonate, the crosslinking agent is at least one of ethyl acetate, sodium dihydropropionate, methyltrichlorosilane, dimethyldichlorosilane or epoxy silane, the catalyst is at least one of sulfuric acid, formic acid, hydrochloric acid, sodium methoxide or potassium hydroxide, and the initiator is at least one of azobisisobutyronitrile, di-tert-butyl peroxide, azobisisoheptyl nitrile or benzoyl peroxide.

2. A high surface energy multifunctional trivalent chromium passivation agent according to claim 1, characterized in that, The trivalent chromium compound is one or more of chromium sulfate, chromium nitrate, chromium phosphate or chromium dihydrogen phosphate.

3. The high surface energy multifunctional trivalent chromium passivation agent according to claim 1, characterized in that, The inorganic acid is at least one of sulfuric acid, phosphoric acid, nitric acid or hydrofluoric acid.

4. The high-surface-energy multifunctional trivalent chromium passivation agent according to claim 1, characterized in that, The silane coupling agent is one or more of amino silane coupling agent, vinyl silane coupling agent or epoxy silane coupling agent.

5. The high surface energy multifunctional trivalent chromium passivation agent according to claim 1, characterized in that, The film forming aid is at least one of cobalt nitrate, sodium nitrate, ammonium fluoride, ammonium hydrogen fluoride, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, nickel sulfate, nickel nitrate, nickel chloride or nickel carbonate.

6. A high surface energy multifunctional trivalent chromium passivation agent according to claim 1, characterized in that, The resin is at least one of water-soluble acrylic resin, water-soluble epoxy resin and water-soluble polyester resin.

7. A process for the preparation of a high surface energy multifunctional trivalent chromium passivation agent according to any one of claims 1 to 6, characterized in that, In water, under stirring, the inorganic acid, the silane coupling agent, the film forming aid, the surface energy aid, the resin and the trivalent chromium compound are added and stirred uniformly to obtain the target product.

8. The high surface energy multifunctional trivalent chromium passivator according to any one of claims 1-6 for passivating steel plates.

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