Chromium-free water-based passivator for tin-plated steel plate and preparation method

Abstract

The invention relates to the technical field of passivator preparation, in particular to a chromium-free water-based passivator for a tin-plated steel plate. Sodium pyrophosphate; ammonium fluotitanate; a silicate; nickel nitrate; zirconium oxytitanate; sodium metaaluminate; manganese dihydrogen phosphate; sodium phytate; oxalic acid; a molybdate; a nanomaterial; a bio-based material; a passivation film material; a cross-linking agent; and an additive. The nano material, the bio-based material, the passivation film material, the cross-linking agent and the additive are creatively added into a traditional passivator, so that the performance and the environmental protection property of the chromium-free water-based passivator are improved, and the actual requirement for surface treatment of a tin-plated steel plate is met.

Description

Technical Field

[0001] The present invention relates to an aqueous passivating agent and a preparation method thereof, and in particular to a chromium-free aqueous passivating agent for tin-plated steel sheets and a preparation method thereof, belonging to the technical field of passivating agent preparation. Background Art

[0002] A tin-plated steel sheet is a steel sheet with a thin layer of metallic tin plated on its surface. During the production process of tin-plated sheets, after the strip steel is tinned and softened, in order to prevent the tin layer on the tin-plated steel sheet from oxidizing and turning yellow during storage, and to improve the sulfur resistance and other properties of the tin-plated steel sheet, a passivating agent is usually used to passivate the tin-plated steel sheet. A chromium-free passivating agent is an environmentally friendly surface treatment agent, which can form a protective film on the surface of the tin-plated steel sheet. This passivating agent does not contain toxic chromium elements, so it is more environmentally friendly and safe.

[0003] Due to the large processing volume of tin-plated steel sheets and the increasing requirements for environmental protection and passivation quality, it has become difficult to meet the increasingly stringent quality requirements of tin-plated steel sheets by using existing conventional chromium-free passivating agents for passivation processing. Existing chromium-free passivating agents have certain disadvantages and challenges in terms of performance, process, cost, and market promotion. How to improve the compactness, antibacterial and corrosion resistance, mechanical strength, and chemical stability of the passivation film, better resist the erosion of the external environment, and at the same time improve the environmental protection of passivation processing has become a technical problem that urgently needs to be solved in the passivation processing of tin-plated steel sheets. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a chromium-free aqueous passivating agent for tin-plated steel sheets with high passivation performance, and the present invention also provides a preparation method of a chromium-free aqueous passivating agent for tin-plated steel sheets.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] A chromium-free aqueous passivating agent for tin-plated steel sheets, which comprises: 3 - 25 g / L of phosphate, 3 - 13 g / L of sodium pyrophosphate, 2 - 15 g / L of ammonium fluotitanate, 3 - 10 g / L of silicate, 1 - 14 g / L of nickel nitrate, 1 - 10 g / L of zirconium oxytitanate, 1 - 11 g / L of sodium metaaluminate, 5 - 13 g / L of manganese dihydrogen phosphate, 2 - 7 g / L of sodium phytate, 2 - 7 g / L of oxalic acid, 1 - 11 g / L of molybdate, 2 - 10 g of nanomaterial, 3 - 8 g of bio-based material, 2 - 6 g of passivation film material, 1 - 7 g / L of cross-linking agent, and 2 - 11 g / L of additive.

[0007] Further, the nanomaterial is one or more mixtures of nano-silica and nano-zinc oxide, and is used to improve the compactness and corrosion resistance of the passivation film.

[0008] Further, the bio-based material is a mixture of one or more of natural plant extracts and biodegradable polymers.

[0009] Further, the method for forming the passivation film includes: compounding a variety of inorganic salts such as phosphates, silicates, and molybdates to form a passivation film with a multiple protection mechanism, and then adding an appropriate amount of organic compounds, where the organic compounds are carboxylic acids and / or alcohols.

[0010] Further, the additive is a mixture of one or more of surfactants and corrosion inhibitors.

[0011] Further, the preparation method of the crosslinking agent includes:

[0012] A1: Raw material preparation: According to the formula of the crosslinking agent, prepare the required raw materials, including the main reactant γ-glycidoxypropyltrimethoxysilane, the catalyst ammonia water, the solvent ethanol / water, the copolymer acrylic monomer, etc.;

[0013] A2: Reaction vessel preparation: Select a suitable reaction vessel, such as a three-necked flask or a reaction kettle equipped with necessary accessories such as a stirrer, a thermometer, and a condenser;

[0014] A3: Raw material addition and mixing: Add the raw materials to the reaction vessel in a certain order and proportion, and start the stirrer for mixing;

[0015] A4: Reaction condition control: According to the reaction characteristics of the crosslinking agent, set appropriate reaction conditions such as temperature, pH, and time, such as setting the temperature at 70 - 90°C, pH at 3.5 - 4.5, and time at 3 - 5 h;

[0016] A5: Reaction process monitoring: During the reaction process, regularly sample and detect the conversion rate of the reactants and the purity of the products;

[0017] A6: Post-treatment and separation: After the reaction is completed, perform post-treatment on the reaction mixture, such as removing ethanol by vacuum distillation and removing oligomers by ultrafiltration, to separate the target product and by-products;

[0018] A7: Obtaining the final product: Adjust the pH to neutral to obtain a transparent crosslinking agent.

[0019] Further, the preparation process of the bio-based material includes: extracting glucose from bio-based renewable resources; converting glucose into lactic acid through a fermentation process; converting lactic acid monomers into an intermediate product, lactide, through a concentration process; after vacuum purification of lactide monomers, ring-opening polymerization is carried out without using a solvent to form polylactic acid; and performing post-treatment on the polymerization product to improve the purity and stability of the material.

[0020] Furthermore, a method for preparing a chromium-free aqueous passivating agent for tinplate includes the following steps:

[0021] S1: Raw material preparation: Weigh each raw material accurately according to the formula ratio to ensure that the purity and quality of the raw materials meet the requirements;

[0022] S1: Dissolution and mixing: Add a part of phosphate, silicate, nickel nitrate, zirconium oxytitanate, sodium metaaluminate, manganese dihydrogen phosphate, sodium phytate, oxalic acid, molybdate, nanomaterials, bio-based materials, passivation film materials, crosslinking agents, and additives into the reaction kettle, and heat to a specific temperature; then add the remaining part of the phosphate that is easily soluble in water and sodium pyrophosphate into the reaction kettle in sequence, stirring while adding to ensure that the raw materials are fully mixed; add ammonium fluotitanate and silicate into the reaction kettle according to the formula in sequence, and continue to stir and mix evenly;

[0023] S2: Adjust the pH value: Use phosphoric acid to adjust the pH value of the solution to the target range (such as 3 - 5) to ensure the stable performance of the passivating solution;

[0024] S3: Filtration and storage: Filter the prepared passivating solution through a filter to remove impurities and particulate matters therein, and then store the filtered passivating solution in a sealed container and keep it in a cool and dry place.

[0025] Furthermore, in S2, a continuous production process is adopted, using a continuous stirred tank reactor (CSTR) or a continuous flow reactor to achieve continuous addition of raw materials and continuous output of products, and green and environmentally friendly solvents are used for both the solvent and the additives.

[0026] Furthermore, in S2, physical field assistance technologies such as ultrasonic waves or microwaves are adopted, and at the same time, intensifying dispersion and homogenization technologies such as high-speed shear mixing and high-pressure homogenization are adopted to accelerate the dissolution and reaction rate of raw materials.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] In this application, nano-oxides are innovatively introduced into the passivating agent formula, which can significantly improve the compactness and corrosion resistance of the passivation film. The small size effect and surface effect of nanomaterials enable them to better fill the micro-defects on the surface of tinplate, forming a more uniform and compact protective film; using bio-based materials as part of the passivating agent can not only reduce environmental pollution but also endow the passivation film with certain biological activities, such as antibacterial and self-healing properties; the compounding of various inorganic salts such as phosphates, silicates, and molybdates can form a passivation film with multiple protection mechanisms.

[0029] Meanwhile, adding an appropriate amount of organic compounds can further improve the adhesion and corrosion resistance of the passivation film; crosslinking the organic and inorganic components in the passivation film using a crosslinking agent can significantly improve the denseness and corrosion resistance of the passivation film. The crosslinked passivation film has stronger mechanical strength and chemical stability, and can better resist the erosion of the external environment.

[0030] In addition, this application introduces a continuous production process in the preparation method, such as a continuous stirring reactor or a continuous flow reactor, to achieve continuous addition of raw materials and continuous production of products. This production method can significantly improve production efficiency, reduce energy consumption and labor costs; during the preparation process, green and environmentally friendly solvents and additives are selected to reduce environmental pollution. For example, water can be used as a solvent, or biodegradable organic solvents can be selected to replace traditional organic solvents; physical field-assisted technologies such as ultrasonic waves or microwaves are used to accelerate the dissolution and reaction rate of raw materials and improve the preparation efficiency. These technologies can generate local high-temperature and high-pressure effects, promoting intermolecular crosslinking and reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the preparation method of the present invention;

[0032] Figure 2 is a schematic diagram of the crosslinking agent process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The technical solution of the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0034] As Figure 1 - Figure 2 shown, the chromium-free aqueous passivating agent and preparation method for tin-plated steel sheets provided in this embodiment include: 3 - 25 g / L of phosphate, 3 - 13 g / L of sodium pyrophosphate, 2 - 15 g / L of ammonium fluotitanate, 3 - 10 g / L of silicate, 1 - 14 g / L of nickel nitrate, 1 - 10 g / L of zirconium oxytitanate, 1 - 11 g / L of sodium metaaluminate, 5 - 13 g / L of manganese dihydrogen phosphate, 2 - 7 g / L of sodium phytate, 2 - 7 g / L of oxalic acid, and 1 - 11 g / L of molybdate.

[0035] 2 - 10 g of nanomaterials; the nanomaterials are one or a mixture of nano-silica and nano-zinc oxide, and are used to enhance the denseness and corrosion resistance of the passivation film. Introducing nano-oxides into the passivating agent formulation can significantly improve the denseness and corrosion resistance of the passivation film. The small size effect and surface effect of the nanomaterials enable them to better fill the micro-defects on the surface of the steel sheet, forming a more uniform and dense protective film.

[0036] 3 - 8 g of bio - based materials; the bio - based materials are one or more mixtures of natural plant extracts and biodegradable polymers. Using bio - based materials (such as natural plant extracts, biodegradable polymers, etc.) as partial components of the passivator can not only reduce environmental pollution but also endow the passivation film with certain biological activities, such as antibacterial and self - repairing properties.

[0037] The preparation process of bio - based materials includes: extracting glucose from bio - based renewable resources such as crops; converting glucose into lactic acid through a fermentation process; transforming lactic acid monomers into an intermediate product, lactide, through a concentration process; after the lactide monomers are purified under vacuum, ring - opening polymerization is carried out without using a solvent to form polylactic acid; and post - treating the polymerization product to improve the purity and stability of the material.

[0038] 2 - 6 g of passivation film materials; the formation method of the passivation film includes: compounding various inorganic salts such as phosphates, silicates, molybdates, etc. to form a passivation film with multiple protection mechanisms, and then adding an appropriate amount of organic compounds. The organic compounds are carboxylic acids and alcohols. By compounding various inorganic salts and organic compounds, a passivation film with more excellent performance can be obtained. For example, compounding various inorganic salts such as phosphates, silicates, molybdates, etc. can form a passivation film with multiple protection mechanisms. At the same time, adding an appropriate amount of organic compounds (such as carboxylic acids, alcohols, etc.) can further improve the adhesion and corrosion resistance of the passivation film.

[0039] 1 - 7 g / L of cross - linker; the preparation method of the cross - linker includes:

[0040] A1: Raw material preparation: According to the formula of the cross - linker, prepare the required raw materials, including the main reactant γ - glycidoxypropyltrimethoxysilane, the catalyst ammonia water, the solvents ethanol / water, and the copolymer acrylic acid monomer, etc.; pay attention to ensuring that the purity and quality of the raw materials meet the requirements;

[0041] A2: Reaction vessel preparation: Select a suitable reaction vessel, such as a three - neck flask, a reaction kettle, etc. equipped with necessary accessories such as a stirrer, a thermometer, a condenser, etc.;

[0042] A3: Raw material feeding and mixing: Feed the raw materials into the reaction vessel in a certain order and proportion, and start the stirrer for mixing to ensure that the raw materials are fully and evenly mixed to improve the reaction efficiency;

[0043] A4: Reaction condition control: According to the reaction characteristics of the cross - linker, set appropriate reaction conditions such as temperature, pH, time, etc., such as setting the temperature at 70 - 90 °C, pH at 3.5 - 4.5, and time at 3 - 5 h, and control the reaction under the optimal conditions;

[0044] A5: Reaction process monitoring: During the reaction process, samples are regularly taken to detect the conversion rate of reactants and the purity of products; the reaction conditions are adjusted according to the detection results to ensure the efficient progress of the reaction and achieve the expected product quality;

[0045] A6: Post-treatment and separation: After the reaction is completed, the reaction mixture is post-treated, such as removing ethanol by vacuum distillation and removing oligomers by ultrafiltration, etc., to separate the target product and by-products;

[0046] A7: Obtaining the final product: Adjust the pH to neutral to obtain a transparent cross-linking agent.

[0047] Cross-linking the organic and inorganic components in the passivation film with the cross-linking agent can significantly improve the compactness and corrosion resistance of the passivation film. The cross-linked passivation film has stronger mechanical strength and chemical stability and can better resist the erosion of the external environment.

[0048] The additive is 2 - 11 g / L, and the additive is one or a mixture of surfactants and corrosion inhibitors.

[0049] Example 2: A preparation method of a chromium-free aqueous passivating agent for tin-plated steel sheets, comprising the following steps:

[0050] S1: Raw material preparation: Accurately weigh each raw material according to the formula ratio to ensure that the purity and quality of the raw materials meet the requirements;

[0051] S2: Dissolution and mixing: First, add 10 g / L of phosphate, 8 g / L of silicate, 6 g / L of nickel nitrate, 8 g / L of zirconium oxytitanate, 6 g / L of sodium metaaluminate, 7 g / L of manganese dihydrogen phosphate, 6 g / L of sodium phytate, 6 g / L of oxalic acid, 6 g / L of molybdate, 6 g of nanomaterial, 6 g of biobased material, 6 g of passivation film material, 6 g / L of cross-linking agent, and 3 g / L of additive into the reaction kettle and heat to an appropriate temperature; then sequentially add 2 g / L of water-soluble phosphate and 3 g / L of sodium pyrophosphate into the reaction kettle, stirring while adding to ensure that the raw materials are fully dissolved; add 4 g / L of ammonium hexafluorotitanate, 1 g / L of silicate, etc. into the reaction kettle according to the formula sequence and continue to stir and mix evenly.

[0052] Adopt a continuous production process, using a continuous stirred tank reactor (CSTR) or a continuous flow reactor to achieve continuous addition of raw materials and continuous output of products. This production method can significantly improve production efficiency, reduce energy consumption and labor costs.

[0053] Implementation details: Design a reasonable continuous production process to ensure that the raw materials can be fully mixed and reacted during the reaction process. At the same time, equipped with advanced on-line monitoring equipment to monitor key parameters such as temperature and pH value during the reaction process in real time to ensure stable product quality.

[0054] Both solvents and additives use green and environmentally friendly solvents; during the preparation process, green and environmentally friendly solvents and additives are selected to reduce environmental pollution. For example, water is used as a solvent, or biodegradable organic solvents are selected to replace traditional organic solvents.

[0055] Implementation details: Screen and evaluate the types of solvents and additives, select materials that meet environmental protection requirements and have excellent performance. At the same time, optimize the ratio of solvents and additives to ensure that the performance of the passivator is not affected.

[0056] Physical field-assisted technologies such as ultrasonic waves or microwaves are used to accelerate the dissolution and reaction rate of raw materials and improve the preparation efficiency; this technology can generate local high-temperature and high-pressure effects, promoting intermolecular collisions and reactions.

[0057] Implementation details: Install an ultrasonic wave or microwave generator in the reaction kettle, set appropriate power and frequency, and optimize the reaction conditions by adjusting the action time and intensity of ultrasonic waves or microwaves to ensure that the performance of the passivator meets the expected requirements.

[0058] Strengthened dispersion and homogenization technologies such as high-speed shear mixing and high-pressure homogenization are used to improve the dispersion and homogenization degree of each component in the solvent.

[0059] Implementation details: Select appropriate dispersion equipment and process parameters such as shear rate and homogenization pressure. By optimizing the dispersion process, ensure that each component in the passivator can be evenly and stably dispersed in the solvent to form a uniform and transparent solution.

[0060] S3: Adjust the pH value: Use phosphoric acid to adjust the pH value of the solution to the target range (such as 3 - 5) to ensure the stable performance of the passivation solution;

[0061] S4: Filtration and storage: Filter the prepared passivation solution through a filter to remove impurities and particulate matter, and then store the filtered passivation solution in a sealed container and keep it in a cool and dry place.

[0062] The above description shows and describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein. Modifications and changes made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A chromium-free water-based passivating agent for tin-plated steel sheets, characterized in that: include: Phosphate 3-25g / L, sodium pyrophosphate 3-13g / L, ammonium fluorotitanate 2-15g / L, silicate 3-10g / L, nickel nitrate 1-14g / L, zirconium titanate 1-10g / L, sodium aluminate 1-11g / L, manganese dihydrogen phosphate 5-13g / L, sodium phytate 2-7g / L, oxalic acid 2-7g / L, molybdate 1-11g / L, nanomaterials 2-10g, bio-based materials 3-8g, passivation film materials 2-6g, cross-linking agent 1-7g / L, additives 2-11g / L.

2. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The nano material is a mixture of one or more of nano silicon dioxide and nano zinc oxide, and is used to improve the compactness and corrosion resistance of the passivation film.

3. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The bio-based material is a mixture of one or more of natural plant extracts and biodegradable polymers.

4. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The method for forming the passivation film comprises: compounding a plurality of inorganic salts such as phosphate, silicate, molybdate, etc. to form a passivation film with multiple protection mechanisms, and then adding a proper amount of organic compounds, wherein the organic compounds are carboxylic acids and / or alcohols.

5. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The additive is a mixture of one or more of a surfactant and a corrosion inhibitor.

6. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The preparation process of the cross-linking agent comprises the following steps: A1: Raw material preparation: According to the formula of the cross-linking agent, prepare the required raw materials, including main reactants, catalysts, solvents, and copolymers; A2: Reaction vessel preparation; A3: Raw material addition and mixing: Add the raw materials into the reaction vessel in a certain order and proportion, and start the agitator to mix; A4: Control of reaction conditions: According to the reaction characteristics of the cross-linking agent, the reaction is controlled to proceed at a specific reaction temperature, pH, and time; A5: Reaction process monitoring: During the reaction process, samples are taken regularly to detect the conversion rate of reactants and the purity of products; A6: Post-treatment and separation: After the reaction is completed, the reaction mixture is post-treated to separate the target product and by-products; A7: Obtaining the final product: Adjust the pH to neutral to obtain a transparent cross-linking agent.

7. The chromium-free aqueous passivating agent for tin-plated steel sheets according to claim 1, characterized in that: The preparation process of the bio-based material includes: Glucose is extracted from bio-based renewable resources; glucose is converted into lactic acid through a fermentation process; lactic acid monomers are converted into the intermediate product lactide through a concentration process; lactide monomers are vacuum purified and then ring-opening polymerized in the absence of solvents to form polylactic acid; the polymer product is post-processed to improve the purity and stability of the material.

8. A method for preparing a chromium-free water-based passivating agent for tin-plated steel sheets, characterized in that: The steps include: S1: Raw material preparation: accurately weigh each raw material according to the formula ratio; S2: Dissolving and mixing: Add part of phosphate, silicate, nickel nitrate, zirconium titanate, sodium aluminate, manganese dihydrogen phosphate, sodium phytate, oxalic acid, molybdate, nanomaterials, bio-based materials, passivation film materials, crosslinking agents, and additives into a reactor and heat to a specific temperature; then add the remaining part of the phosphate that is easily soluble in water and sodium pyrophosphate into the reactor in sequence, stirring while adding to ensure that the raw materials are fully mixed; add ammonium fluorotitanate and silicate into the reactor in sequence according to the formula, and continue to stir and mix evenly; S3: Adjust pH value: Use phosphoric acid to adjust the pH value of the solution to the target range to ensure the stable performance of the passivation solution; S4: Filtration and storage: Filter the prepared passivation solution through a filter to remove impurities and particulate matter, and then store the filtered passivation solution in a sealed container in a cool and dry place.

9. The preparation method according to claim 8, characterized in that: The S2 adopts a continuous production process, using a continuous stirred reactor or a continuous flow reactor to achieve continuous addition of raw materials and continuous output of products, and the solvent and auxiliary agent are both green and environmentally friendly solvents.

10. The preparation method according to claim 8, characterized in that: The S2 uses ultrasonic or microwave physical field auxiliary technology, as well as enhanced dispersion and homogenization technology to accelerate the dissolution and reaction rate of the raw materials.

Images